12.Wk8Dis

C H A P T E R 2 2

Lower extremity limb pain A useful framework for differentiating limb pain involves determining whether symptoms are caused by musculoskeletal injury, musculoskeletal or joint disease, systemic disease, or a combination of factors. Pain can result from direct reaction in tissues, secondary reaction in adjacent tissues, or referral from a proximal or distal lesion or from organs such as the heart or kidney. For example, lower extremity pain is often referred from the low back and emanates from irritated nerve roots, or pain is secondary to myofascial syndromes of the low back, pelvic, and hip musculature. In children, aches and pains in limbs are common. However, the presence, location, and intensity of the pain are often difficult to assess.

Diagnostic reasoning: Focused history Is the pain related to an urgent problem that needs immediate treatment to avoid disability or death? Key Questions

• Have you had a recent injury? • Can you describe exactly how the injury occurred? • Do you have any other symptoms such as fatigue, fever, or swollen joints? • What is the severity of the pain? Does it occur with exercise or rest?

Injury Injuries to the musculoskeletal system can range from simple muscle strain to a significant fracture associated with nerve or vascular injury. Therefore, when a patient has a history of trauma, the priority is to assess the vascular integrity of the limb. Neurologic integrity is next. Symptoms of coldness, severe pain, or paresthesia are signals the that physical examination should immediately assess the extent of injury and the need for emergency treatment. Acute pain and swelling that follow trauma usually indicate injury to a previously normal structure. Compartment syndrome is an injury that involves both vascular integrity and neurologic functioning. This condition develops when trauma to an extremity causes swelling and pressure that compromises blood flow to the affected muscles and nerves. Surgical decompression is needed, and prompt diagnosis is crucial to avoid amputation and other complications.

If the injury does not warrant urgent attention, obtain further history. Ask questions that specify the mechanism of injury, such as a direct blow or impact, landing position after a fall, twisting, jumping, running, overstretching, or overuse. A severe crush injury puts the patient at high risk for developing compartment syndrome—among other complications—in the crushed limb. When discussing the precipitating event, ask the patient to describe any noise, such as snapping, popping, or breaking that may have occurred with the injury.

Constitutional symptoms The presence of generalized symptoms, such as fever, weight loss, general malaise, or hot swollen joints, suggests the presence of a systemic disorder such as infection or rheumatic disease. Infection in a child causes systemic illness and the child appears ill.

Fever related to joint problems can be the result of hematogenous seeding by an organism, direct invasion as a result of trauma or puncture, or migration from an adjacent area of infection. In rheumatic fever, a β­hemolytic streptococcal infection precedes the initial joint pain by 1 to 3 weeks. Often the hip joint may be the first of many

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joints affected before polyarticular migratory involvement occurs. The fever is sustained, not intermittent. Fever spikes are seen with chronic forms of arthritis in children.

Severity of pain Unrelenting diffuse pain, often occurring at night, is an indication of bone involvement either through bone cancer or an infection such as osteomyelitis, arthritis, or septic hip. Claudication and neurogenic pain increase with activity and decrease with rest; more immediately for vascular causes and more slowly for neurogenic causes.

Severe nontraumatic pain that occurs with pallor, paresthesia, or paralysis in a cold limb may be the result of acute limb ischemia, which requires emergent treatment to avoid amputation. Acute limb ischemia is often the result of worsening atherosclerotic peripheral vascular disease, in which a narrowed artery becomes occluded secondary to thrombosis or embolism. On examination, the affected limb will have diminished or absent peripheral pulses. Acute limb ischemia requires urgent consultation with a vascular surgeon for possible revascularization.

In young children, failure to voluntarily move an arm or leg can be a sign of pain and is called pseudoparalysis.

Radiating leg pain associated with saddle anesthesia and loss of bladder or bowel control may indicate cauda equine syndrome and requires immediate surgical intervention (see Chapter 24).

What does the location of the pain tell me? Key Questions

• Where does it hurt? • Is the pain local or generalized?

Location Location of pain provides a clue for identifying the site where the pain originates. Local pain receptors signal the site of irritation, and an increase in sensitivity (hyperesthesia) results. Referred pain generally involves the muscle chains, nerve pathways, and vessels. Unilateral, circumscribed limb or quadrant pain involves autonomic nerve fibers. Bilateral pain is more likely to originate from systemic involvement. Diffuse pain with inconsistent distribution may be the result of psychosomatic conditions such as depression and anxiety. Diffuse pain over trigger points is indicative of fibromyalgia. Collagen diseases and connective tissue diseases can affect one or more joints. The more vaguely defined the boundaries of the pain, the deeper or more central is the location of the somatic irritation. The obturator nerve has sensory branches that innervate the hip and skin on the medial aspect of the thigh, causing pain that originates in the hip but is referred to the knee.

Could this be caused by a sprain or strain? Key Questions

• Describe how the injury occurred. • Did you hear a noise with the injury, such as a ripping or cracking sound? • Were you able to use the limb after the injury?

Strain Whereas strains involve injury to muscles and tendons, sprains involve injury to ligamentous structures. Both types of injuries can produce a ripping or tearing sound and range in severity from minor damage to a complete tear. Injuries are generally classified as mild, moderate, or severe. A moderate to severe strain or sprain may involve some loss of joint or ligament stability. Strains may be acute or chronic. Ankle injury commonly occurs when lateral stress is applied while the joint is plantar flexed. This position is the least stable position of the ankle, and the overstretched ligaments are more susceptible to eversion or inversion forces.

Sprain

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Sprains cause minimal to moderate pain, increasing 1 to 2 days after the trauma when the inflammatory process begins. A complete disruption that severs the sensory nerve fibers within the structure will cause little pain, whereas a partial injury irritates sensory fibers, and may produce intense pain.

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In children, ligaments and joint capsules are two to five times stronger than the epiphysis; therefore, growth plate injuries are more common than sprains.

Fracture A fracture produces diffuse swelling around the injured bone soon after injury. Deformity will be present if the fracture is displaced. A patient may report hearing a crack and being disabled by the increased severity of pain with weight bearing or movement of the limb. With a stress fracture, there may be mild swelling and tenderness and pain with weight bearing.

If there is no history of trauma or a precipitating event, what else is causing the pain? Key Questions

• Can you describe your usual daily activities at home, at work, and with hobbies? • How does the pain affect your activities? • Do you have other illnesses?

Activities A person may adapt to chronic musculoskeletal problems by using an assistive device, such as a cane, or by limiting activities. Rheumatic disorders produce symmetrical discomfort and pain with inactivity. Noninflammatory conditions are often associated with asymmetrical pain after extended use. Children will often avoid walking on a limb that causes pain. Infants will have lack of movement of the limb with irritability and fussiness when the limb is moved passively.

Other illnesses The presence of coronary artery disease increases the risk of arterial insufficiency and associated claudication pain. Peripheral neuropathy associated with diabetes can produce numbness and burning pain or “pins and needles” sensation, especially in the lower extremities. Pain may be sequelae of a prior cerebrovascular accident or Gillian­Barre syndrome.

History of injury

In joint pain with injury, what do I need to know about the specific joints involved? Key Questions

• Is the pain affected by weight bearing or activity? • Did you feel a sense of “giving way”? • Did you hear a pop, tear, or other sound? • In what position was your leg when the injury occurred?

Continuing with an activity means the injury did not totally disrupt any ligamentous structures. An inability to straighten or bend the knee suggests a mechanical disruption such as a patellar dislocation or meniscus tear. In chondromalacia, the patient can bend the knee, but the movement is usually painful.

A loud pop is virtually diagnostic of an anterior cruciate ligament (ACL) tear. A ripping sound suggests a meniscus injury. A cracking sound may signify a bony injury or dislocation of the patella.

A quick change in direction, or a sudden stop, may put more force on the ligaments than they can dissipate, resulting in an acute rupture. A sudden twisting injury is likely to represent a meniscus tear and a serious ligament disruption. Running or jumping activities are commonly associated with knee and ankle injuries.

In children, 10% to 20% of knee symptoms are the result of a problem in the hip joint.

Could this be musculoskeletal or joint disease? Key Questions

• Can you describe the pain?

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In general, sharp, piercing, stabbing, cutting, pinching, and gnawing pain is most common with lesions of the nerves and skin. Dull, tearing, boring, burning, and cramping are common terms used to describe pain arising from deeper structures such as muscles and joints. Pulsating, pounding, throbbing, and hammering are common descriptions of vascular pain. Gradually increasing sensations of pressure, tension, heaviness, and calf pain indicate venous obstruction. Severe pain that develops over 1 to 4 days is typical of osteomyelitis or septic arthritis and is an emergency condition.

Muscle pain is caused by receptors located in bursa, muscle fibers, ligaments, and tendon attachments. It is a diffuse, dull, gnawing, boring, or tearing pain that increases with use and decreases with rest.

Intraarticular pain arises from receptors of the synovial membrane, joint capsule, or the fibrochondral layers of the articular surfaces. Joint pain is either inflammatory or degenerative. Inflammatory joint pain radiates diffusely to surrounding tissues. It is intense, sharp, burning, boring, or pulsating (effusion) pain. It persists during rest and is evident especially at night, worsening in the morning with stiffness that lasts more than 45 minutes and improving throughout the day.

Degenerative joint pain radiates to the soft tissue structures around the joint (i.e., muscles, ligaments, tendons). It is a dull, gnawing sensation associated with muscle pain, or it can be a sharp, acute pain that increases with overuse.

Bone lesions cause a dull ache; periosteal pain is sharp, not well localized, and increases in intensity with dependency of the extremity.

Neuralgic pain occurs in the distribution of a peripheral nerve or nerve root. The pain is stabbing, burning or cutting.

What does the history of swelling tell me? Key Questions

• Is there any swelling? • When did the swelling begin?

Swelling Swelling around a joint is always abnormal. Children do not always recognize swelling; they often report that they cannot squat down or flex their knee fully because it feels “full or tight.” Generally, swelling secondary to trauma develops immediately or within 2 hours after an injury; swelling 6 to 24 hours after an injury is usually of synovial origin such as a meniscal tear, subluxation, dislocation, or ligamentous damage. Swelling after 24 hours suggests an inflammatory response.

Is this an acute or a chronic problem? Key Questions

• When did the pain first occur? • When did you first notice a problem?

Pain experienced hours after an injury or physical activity is usually caused by acute extensor injury or overuse. Severe ligament sprain is manifested as an immediately disabling pain at the moment of the injury.

Determining if the complaint is acute or chronic helps differentiate the cause. Whereas chronic joint problems compound each other, intermittent or episodic pain is characteristic of diseases of the musculoskeletal system. In children, limping or not using the extremity may be a signal that the child is experiencing pain. Parents will often note the loss of motion in an extremity or an awkward gait; they often report that the child is unable to perform routine activities.

How is activity affected? Key Questions

• What are your usual activities? • What activity makes the pain worse? • What movements make the pain worse?

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Repetitive microtrauma in the lower extremities from inappropriate rate and intensity of training, poorly fitting shoes, or unsuitable playing surfaces can cause stress fractures of the weight­bearing bones of the lower limbs. Pain is worse over the site of the fracture.

In children, pain in the groin or referred to the knee and anterior thigh that is intermittent after activity and gradually becomes constant may indicate Legg­Calvé­Perthes disease (LCPD).

Intraarticular lesions usually worsen with joint motion and sports activities. Intraosseous tumors are less sensitive to joint motion.

In children with a septic hip, pain increases with movement.

What does joint stiffness or locking tell me? Key Questions

• Have you had any joint stiffness? • Does activity make the stiffness worse or better? • Do you have locking of the knee?

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Joint locking Locking of the knee is an abrupt occurrence in which the patient complains that something “gets in the way” and is unable to fully extend the knee. Manipulation of the leg often results in an equally abrupt unlocking. This is usually a sign of a chronic unstable meniscus tear. Stiffness is a common feature of any inflammatory arthropathy. Whereas arthritic stiffness and pain are alleviated by activity, mechanical problems are aggravated by activity.

What does the history of a limp tell me? Key Questions

• Is there pain with the limp? • Did the limp develop suddenly? • Is the limp constant or intermittent? • What is the effect of running or climbing stairs?

Limp Limping is a pathological alteration of a smooth, regular gait pattern and is never normal. Gait can be divided into two phases: stance and swing. The stance phase starts with the foot in contact with the ground and ends with the toe being lifted off the ground; the limb supports all the body weight. The swing phase begins with the toe elevated from the ground and ends with the heel strike. During the swing phase, the foot is not touching the ground; the pelvis rotates forward and tilts slightly while the trunk maintains a neutral position. Limp after strenuous running may indicate a stress fracture.

Quadriceps weakness causes difficulty in climbing stairs. During ambulation, this weakness causes the knee to be unstable on heel strike, and assistance is needed to push the knee manually into an extended position. A knee flexion contracture of just 5 degrees increases risk for fall.

Neuromuscular diseases can result in progressive and painless muscle weakness or spasticity that affects ambulation in a variety of ways.

Symptoms of pain and limping in children may be incorrectly attributed to trauma instead of a more serious problem such as neoplastic tumors or bone infections.

Could this be caused by systemic disease? Key Questions

• Have you been treated with antibiotics recently? • Have you had any recent immunizations? • Does the pain awaken you at night? • Is the pain worse at night?

Medications Certain antibiotics can cause serum sickness in children, producing joint pain and fever. In adults, fluoroquinolone antibiotics can produce tendinitis or tendon rupture.

Night pain Intense pain may occur at rest and during the night. At first, the pain may occur only when the patient changes position while sleeping. However, sleep becomes disrupted as the pain increases. Report by an adolescent of night pain is a red flag for the intraosseous pain of a bone tumor. Pain in the lower limbs in children 6 to 12 years of age who are in a rapid linear growth period may cause the child to awaken at night. The cause of these “growing pains” is unknown, but they are thought to result from muscle structures that have to catch up with bone growth. The pains are usually bilateral with no objective findings.

Could lyme disease be the cause of pain? Key Questions

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• Have you been camping or spending time in wooded areas? • Have you noticed any skin rashes?

Lyme disease Lyme disease is an infection caused by the tick­borne spirochete Borrelia burgdorferi. Early symptoms include diffuse arthralgias, myalgias, fever, chills, and a characteristic targetlike rash. The arthralgia may involve multiple joints, but the knee is most often affected. Joint manifestations occur 1 week to 2 years after the initial illness. Patients may or may not recall the antecedent tick bite or exposure.

What does the health history tell me? Key Questions

• Have you had anything like this before? • Do you have a chronic disease? • Could you have been exposed to any sexually transmitted infection? • Have you been treated with cortisone?

Chronic conditions Chronic diseases, such as sickle cell anemia, inflammatory bowel disease, Crohn disease, hypothyroidism, hyperthyroidism, and collagen vascular diseases, are frequently associated with skin rashes, psoriasis, and limb and joint pain.

Gonorrhea disseminates to the musculoskeletal system in 1% to 3% of individuals with the disease. Of these, more than 80% develop arthritis. C. trachomatis infection can produce a triad of symptoms that include arthritis, uveitis, and urethritis.

Patients with chronic illness that requires long­term administration of corticosteroids are at risk for cortisone­ induced necrosis of the hip. Sickle cell anemia can cause hip pain during a sickle cell crisis. Viral infections may cause diffuse myalgia.

Is this a mixed condition? Consider the possibility that a patient may have a condition that is a mix of factors such as a systemic disorder that has resulted in an acute injury. Clues to mixed etiology might include an injury that seems out of proportion to the extent of the precipitating activity or the presence of a chronic condition and other symptoms that might point to an undetected chronic condition. It is important to evaluate the limb pain in the context of the whole person.

Diagnostic reasoning: Focused physical examination Evaluation of musculoskeletal injuries should include examination of joint stability, deformity, and function. Examination should be done as soon as possible after an injury for an accurate diagnosis. Observe for symmetry, and then functionally assess limbs and joints bilaterally beginning with the unaffected side. Order the examination so that the most painful tests will be done last. Figures 22.1 and 22.2 illustrate anatomical landmarks of the knee and ankle. Table 22.2 describes selected tests used to assess for lower extremity musculoskeletal disorders.

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FIGURE 22.1 Basic anatomy of the right knee. Source: (From Patton K, Thibodeau G: Anatomy and physiology, ed. 9, St. Louis, 2016, Elsevier.)

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FIGURE 22.2 The lateral ankle ligaments—anterior and posterior talofibular (ATF and PTF, respectively) and calcaneofibular (CF). Also shown are the anterior inferior tibiofibular (AITF) ligament and the beginning of the interosseous membrane (IM). Source: (From Auerbach P: Wilderness medicine, St. Louis, 2007, Mosby.)

Observe the patient Subtle clues of physical abuse must be considered when the patient history is not consistent with the type or extent of injury. Abuse should always be considered in an infant when symptoms and history suggest a fracture, multiple injuries, rotational injuries, or multiple bruises in different stages of healing. Radiographs may show previous fractures.

People who have septic joints appear ill, and movement of the joint will increase the pain. Inspect the patient with minimal clothing obstructing your view of movements. A child with a septic hip lies with the thigh in a position of flexion, abduction, and external rotation and cries when the lower limb is moved.

In adults, an internally rotated abducted leg is the posture assumed with a posterior hip dislocation. An externally rotated hip and shortened lower extremity are signs of hip fracture.

General stiffness or limitation of motion of a joint causes the surrounding joints to accommodate by moving with greater excursion or range of movement than usual. This makes the gait appear irregular or jerky.

Look for limp Pain, weakness, and deformity cause limping. Limping will be accentuated if the patient is asked to walk on the heels or tiptoes.

Common abnormal gaits related to limping are Trendelenburg gait, antalgic gait, and circumduction gait. Trendelenburg gait is a ducklike gait that reflects unilateral weakness of the gluteus medius muscle. The pelvis drops on the unaffected side during weight bearing on the affected side. In antalgic gait, there is an acute one­ sided limp because the patient takes quick soft steps to shorten the

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period of weight bearing on the involved extremity. Stance time on the affected limb is decreased while stride length of the opposite side is shortened, allowing a quicker return of weight bearing to the unaffected limb. This is a reflex response to weight bearing on a painful limb.

Circumduction gait is seen with pathology of the foot or ankle and reduces discomfort by limiting movement of the ankle. The gait is characterized by a circular outward swing of the leg and external rotation of the foot that requires less ankle movement. External rotation of the entire extremity is seen with slipped capital femoral epiphysis. A video of abnormal gaits can be viewed at https://www.youtube.com/watch?v=Q98WKpwIpkE.

Have the patient stand on one foot and then the other. When standing on one leg, the gluteus medius on that side maintains the opposite side of the pelvis level, balancing the trunk over the weight­bearing hip. If the hip abductors are weak or painful, the opposite side of the pelvis dips down during the stance phase. With each step, the trunk shifts toward the side of a painful or weak extremity to decrease the force transmitted through the extremity to the hip.

Assessment of gait is best done either before or after examination, when patients are less aware that they are being observed.

Ankle plantar flexion and dorsiflexion are necessary for normal gait. If plantar flexion is restricted, there is no push­off, and the forefoot and heel come off the floor at the same time. The result is a higher knee lift, and the forefoot may slap against the floor. This condition is seen with weakness from peroneal nerve injury or with the painful dorsiflexion associated with shin splints.

Observe the patient walking with and without shoes. If a child walks without difficulty with shoes off, the shoes are probably the problem. Inadequate shoe width is a common source of foot pain in children.

Have the patient locate the pain Have the patient point to the area of pain. Location of pain and the actual area of pathology may not be consistent. Hip pain often is referred to the knee area because the anterior branch of the obturator nerve passes close to the hip joint and, if irritated, provides a painful sensation to the medial side of the knee. True hip joint pain arises in the trochanteric bursa and is perceived in the groin area.

Pain in the groin, lateral hip, or knee in a child may indicate LCPD. Pain in the groin, buttocks, or lateral hip in a child may indicate slipped femoral capital epiphysis. Vague, nebulous discomfort in the front of the thighs, in the calves, and behind the knees located outside of

the joints in a child may indicate growing pains.

Note any deformities Fractures generally produce unilateral deformities or swelling in the extremities. Inflammatory and degenerative joint diseases produce observable joint swelling and deformity that usually occurs bilaterally.

Assess vital signs Elevated temperatures are seen with neoplastic, systemic, and infectious processes such as osteomyelitis, septic arthritis and septic hip in children, and rheumatic disease. Neonates may not exhibit a fever with a septic hip but may refuse to feed and will exhibit other symptoms of septicemia such as lethargy and subnormal temperature. Palpate for the quality and presence of pulses in any injured limb and compare with the opposite side. Assess peripheral pulses for presence, rate, regularity, strength, and equality.

Inspect the skin and nails Chronic venous obstruction in the lower extremities causes a brownish coloring of the skin, and arterial insufficiency causes thin, shiny skin with an absence of hair and brittle nails.

Lyme disease usually presents with a rash before joint involvement; however, rash may occur concurrently. The rash, characteristically found on the trunk, begins as an erythematous papule that develops into an annular lesion with a clear center. Concentric rings may develop, giving it a bull’s­eye appearance (erythema migrans).

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Inspect the skin for redness and inflammation. Look for a puncture or an abscess that could be the source of infection and seeding if a septic joint or osteomyelitis is suspected. Swelling and redness in a joint or in the midshaft of the tibia may be caused by osteomyelitis.

Look for an ingrown toenail that may alter gait. When the nails are trimmed by rounding off the edges, the hypertrophied and inflamed soft tissue fold can overlap the nail, and ingrowth at the distal margin will occur. Ingrown toenail pain is enhanced when tight­fitting shoes compress the soft tissues around the nail.

Look for ecchymosis and bruising. These indicate trauma as a source for pain and raise the suspicion of abuse. Ecchymosis indicates underlying bleeding and disruption of soft tissue or bone. Ecchymosis changes color over a period of days. Initially, the color is dark red or violet, and in 1 to 3 days, the bruise is blue­brown; in 1 week, it is yellow­green; and after 1 week, it is light brown. Ecchymosis resolves within 2 to 4 weeks.

Ecchymosis in the popliteal fossa after dislocation of the knee may be a sign of arterial disruption. Hemarthrosis, or bleeding into a joint, usually occurs within 1 to 2 hours after an injury and can occur secondary to hemophilia or other bleeding disorders, or it can be associated with visible ecchymoses caused by blood leaking into soft tissues.

Swelling and redness of a joint indicate underlying infection or inflammation. Edema will present as an asymmetrical area of swelling. Effusion, or fluid in the joint capsule, distends the joint in a smooth, symmetrical manner.

Observe the muscles around the painful limb area. Decreased muscle tone or atrophy from disuse begins immediately after injury, although it will not be clinically apparent for approximately 1 week. Neurologic injury may also be a cause of atrophy.

Asymmetrical gluteal folds may indicate a congenital dislocated hip (Fig. 22.3).

FIGURE 22.3 Ortolani sign for congenital dislocation of the hip. A “click” is palpable or audible as the hip is reduced by abduction. If the test result is negative, the examination should always be repeated in 2 to 4 months. Source: (Swartz MH: Textbook of physical diagnosis: history and examination, ed. 7, Philadelphia, 2014, Saunders.)

Measure limb circumference and length Use a tape measure to locate points at which to measure and compare limb circumference. Differences may be the result of muscle atrophy or edema. Measure the circumference of both calves in a patient who has unilateral lower limb edema. Measurements are taken 10 cm inferior to the anterior tibial tuberosity and compared

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bilaterally. A difference of 2 to 3 cm is considered a significant discrepancy and may indicate deep vein thrombosis (DVT) in a swollen leg.

To measure leg length, have the patient lie supine with legs in comparable positions and measure the distance from the anterior iliac spine to the medial malleoli of the ankles. If a discrepancy is found, ask the patient to lie supine with knees flexed 90 degrees and feet flat on the table. If one knee is higher, the tibia of that extremity is longer. If one knee projects further anteriorly, the femur of that extremity is longer.

Palpate extremities and joints Always palpate those areas that are suspected to be painless first and then compare with the affected limb.

Determine if there is edema (e.g., presence of interstitial fluid). Induration is interstitial swelling that has progressed and is now firm. An effusion is a collection of fluid in the joint capsule, which can be the result of rupture of a vascular structure or a synovial secretory response to an inflammatory process. The consistency of the fluid is noteworthy. Pus has a thick consistency and is less fluctuant than synovial fluid. Hematoma has a more gel­like consistency. Swelling in an ankle sprain is diffuse and nonfluctuant. Knee ligament sprain is much more fluctuant. To assess for fluid in the knee joint, press above the knee and watch the concave or shallow areas of the joint become distended and bulge on either side of the kneecap. Note that swelling can extend above and below the point of pathology.

In severe knee trauma, rupture of the capsule allows fluid to escape into surrounding tissues, and less distention may be more apparent than with lesser injuries.

Palpate for fluid bulge if the knee is painful. Milk up the fluid into the suprapatellar pouch and then bring the hand down the lateral aspect of the knee, looking for a medial fluid bulge. Palpate deeply to detect muscle fibrillation, fasciculation, or tumors.

Feel for heat in the affected joint, which can indicate an inflammatory or infectious process. Evaluate the joint for crepitus, both palpable and auditory. Tendinitis may produce a grating sensation on palpation of the ligament or a grating sound with movement.

Perform passive and active range of motion of the hips, knees, and ankles Range of motion (ROM) may be limited because of pain, weakness, or deformity.

If there is joint pathology, pain will be the same with active and passive motion. If the disease is outside the joint or extraarticular, passive motion may be painless, but active motion produces pain. During passive tests, move the joint until an end point or end range is felt to help determine the affected structure.

There are six end points to note when assessing joint movement: (1) bone­to­bone sensation, felt with an osteophyte or abnormal bone development; (2) spasm, which can indicate severe ligamentous injury; (3) capsular feel or a firm arrested movement with some give to it, which can indicate chronic joint effusion, arthritis, or capsular scarring; (4) spring block or joint rebound at the end of range of movement, caused by an articular derangement or an intraarticular body; (5) tissue approximation, a normal end feel caused by tissue limiting further movement, such as the biceps muscle limiting elbow flexion; and (6) empty end feel, present when there is no tissue resistance, but the patient stops the movement because of pain. This last condition indicates bursitis, extraarticular abscess, or tumor.

Test for muscle strength Test for lower extremity flexor and extensor strength against resistance of both the proximal and distal muscle groups (Table 22.1). Proximal muscle weakness is seen in myopathic

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disorders. Distal muscle weakness is seen secondary to a neuropathic process. Generally, if the opposite side is normal, strength should be compared with it.

Table 22.1 Muscle Strength Test

GRADE MUSCLE STRENGTH TERM

0 No palpable contraction Zero

1 Muscle contracts but part does not move Trace

2 Muscle moves part but not against gravity Poor

3 Muscle moves part through range against gravity Fair

4 Muscle moves part even with resistance Good

5 Normal strength against resistance present Excellent

In the presence of significant pain, muscle strength may be unreliable. If the contraction is strong and painful, the pathology is caused by mild musculotendinous damage. If the contraction is weak and painful, the pathology is the result of severe musculotendinous damage. If the contraction is weak and painless, the pathology results from a neurologic lesion (paresis).

Perform a neurologic examination A complete assessment of sensory and motor function and deep tendon reflexes should be done on the affected and contralateral limbs. If systemic illness is suspected, perform a complete neurologic examination. A referral is indicated if initial treatment does not adequately control pain, if function loss is present, or if the patient is immunocompromised.

Laboratory and diagnostic studies

Complete blood count A complete blood count is obtained to evaluate for anemia associated with chronic disease, infection, or neoplasm. An altered white blood cell (WBC) count may indicate infection or leukemia.

Erythrocyte sedimentation rate An erythrocyte sedimentation rate (ESR) is elevated when inflammation is present. It is a nonspecific test.

Joint aspiration Joint aspiration is performed to assess synovial fluid for elevated WBC count, Gram stain, culture and sensitivity, crystal analysis, presence of glucose, and consistency or “string test.” This procedure is performed using local anesthesia under sterile technique. Synovial fluid will flow easily when the joint capsule is penetrated.

Radiography Obtain at least two radiographic views, anteroposterior and lateral, because injuries are not always apparent on a single view. Any evidence of fracture or dislocation will require orthopedic attention. Sometimes radiographic comparisons with the opposite limb may be useful. Traumatic knee injuries should include four radiographic views: anteroposterior, lateral, tunnel (intracondylar notch), and a 30­degree sunrise (patella). Magnetic resonance imaging (MRI), computed tomography (CT), or bone scanning is usually ordered by a specialist. MRI is usually used in spine, joint, and soft tissue imaging. CT scans are usually performed for bone visualization.

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Antinuclear antibodies Antinuclear antibody (ANA) tests are positive with high titers in rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). However, other conditions, such as advanced age, medications, and other connective tissue disease, can produce positive antibody titers.

Rheumatoid factor Rheumatoid factor (RF) is the single most useful test to confirm a diagnosis of RA and is positive in 80% of patients with this disease. RF can be positive years before clinical symptoms appear.

C4 complement C4 complement determines serum hemolytic complement activity, a protein that binds antigen–antibody complexes for the purpose of lysis. Complement is increased in active inflammatory disease and in autoimmune disorders such as juvenile rheumatoid arthritis.

C-reactive protein C­reactive protein (CRP) indicates the presence of abnormal plasma protein or a nonspecific response to inflammation caused by both infectious and noninfectious processes. CRP is elevated in RA and infection.

Lyme titer enzyme-linked immunosorbent assay serology Enzyme­linked immunosorbent assay (ELISA) detects antibodies against B. burgdorferi, which causes Lyme disease. However, it may not detect antibodies for several weeks after the onset of infection.

Differential diagnosis

Causes of emergent lower extremity pain

Compartment syndrome Acute compartment syndrome is an injury that involves both vascular integrity and neurological functioning. This condition develops when trauma to an extremity, often fractures to long bones, causes swelling and pressure that compromises blood flow to the affected muscles and nerves. Surgical decompression is needed, and prompt diagnosis is crucial to avoid amputation and other complications.

Cauda equine syndrome Compression of the S1 nerve root produces back pain, bladder and bowel dysfunction, and motor weakness of the lower extremities with radiculopathy (see Chapter 24). This syndrome is a surgical emergency.

Causes of non-emergent lower extremity pain

Musculoskeletal inflammation

Tenosynovitis (Tendinitis) Soft tissue disorders of tendinitis, bursitis, and fibrositis tend to co­occur. Tenosynovitis is a term that refers to inflammation of the tendon and tendon sheath.

The patient’s chief concern will be pain that is worse with movement and swelling around the affected area. Occupational and recreational history will provide vital clues to a traumatic or overuse cause of pain. People with arthritis may have tendinitis secondary to joint disease. Crepitus may be felt on palpation of the tendon.

Bursitis Bursitis is inflammation of a sac lined with synovial fluid, most often secondary to traumatic tenosynovitis of the hips and knees. Bursitis is caused by overuse and trauma and may be associated with RA. If isometric contraction of a group of muscles causes pain, the muscles, tendons, or both may be involved. Bursitis causes an

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aching pain that radiates to points of tendon insertion or further along the limb. Muscle weakness may also be present. Palpation reveals local tenderness and swelling without full range of joint motion.

Osteomyelitis Osteomyelitis, a pyogenic infection of bone, presents differently depending on the age of the patient as well as the bone involved. It should be suspected in any patient who reports pain in long or flat bones and walks with an antalgic limp. Pressure ulcers caused by immobility or neuropathy are a major cause of osteomyelitis. Fever, chills, and vomiting are present in acute osteomyelitis but may not occur in the neonate or young infant. Chronic osteomyelitis is characterized by relapse of pain, erythema, swelling, or purulent discharge. The hallmark symptom is a constant local pain that progressively worsens. The slightest motion of the limb aggravates the pain. The child keeps the limb motionless. Laboratory findings show increased WBC count, ESR, and CRP. Radiographs may show bone destruction or deep soft tissue swelling at the site of infection.

Joint inflammation

Osteoarthritis Osteoarthritis (OA) is a degenerative disease of joint cartilage that results in osteophyte (spur) development and synovial inflammation. It is the most common form of arthritis and is present to some extent in all older adults. Patients report joint stiffness, pain, and limited movement, most often of the spine (cervical and lumbar) and large proximal joints (e.g., knee, hip). Symptoms may be asymmetrical. Heberden nodes develop on the distal interphalangeal joints. Patients at increased risk have a history of joint trauma, are obese, or have diabetes mellitus. Acute arthritis is associated with an increased ESR, and radiographs will show spurs, joint deformity, and erosive changes.

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Rheumatoid arthritis Symptoms of RA include morning stiffness of symmetrical small joints in the hands and feet, swelling, and progressive fatigue. Other symptoms include fever, weight loss, anorexia, and diaphoresis. Pericarditis, pleuritis, and vasculitis are associated conditions. Laboratory data may disclose a normochromic, normocytic anemia, an elevated ESR, and a positive rheumatoid factor in 75% to 90% of patients. Radiographs may show bony erosion at the joint margins and joint deformities. Box 22.1 lists criteria for the diagnosis of RA.

Box 22.1

D i a g n o s t i c C r i t e r i a f o r R h e u m a t o i d A r t h r i t i s ( F o u r C r i t e r i a M u s t B e P r e s e n t )

• Morning stiffness ≤1 hour before improvement for >6 weeks • Arthritis of three or more joints for >6 weeks • Arthritis of hand joints for >6 weeks • Symmetrical arthritis of same joint • Rheumatoid nodules • Positive serum rheumatoid factor • Radiographic changes showing erosions or bony decalcification

Modified from Arnett FC, Edworthy SM, Bloch DA, et al: The American Rheumatism Association 1987 revised criteria for the classification of rheumatoid arthritis, Arthritis Rheum 31:315, 1988.

Juvenile rheumatoid arthritis Juvenile rheumatoid arthritis is the most common connective tissue disease in children. The patient presents with fatigue, low­grade fever, weight loss, and failure to grow. Night pain and morning stiffness that improve with activity are common symptoms. Younger children may present with irritability, refusal to walk, or guarding of a joint. The disease may be systemic, affect fewer than four joints (pauciarticular), or affect more than four joints (polyarticular). Laboratory findings show anemia, leukocytosis, and thrombocytosis. Rheumatoid factor and ANA may be negative. ESR is elevated.

Septic arthritis Septic arthritis is sudden pain and inflammation of a single joint, sometimes associated with systemic signs such as fever, malaise, and diaphoresis. The hip is a common site of blood­borne joint infection in neonates, infants, and young children. The presentation depends on the age of the child. A neonate may be afebrile but irritable, refusing to feed and failing to gain weight. In an older child, the onset of pain and fever is acute, and the child refuses to bear weight. ROM of the hip is markedly restricted and very painful.

In adults, migratory joint pain and tenosynovitis may follow 2 to 4 weeks after a mucosal site infection with Neisseria gonorrhoeae. Knee, wrist, ankle, and hand joints are most commonly affected. Joint aspiration shows increased WBC count, and culture of fluid or pus may reveal bacterial, tubercular, fungal, syphilitic, and viral organisms. The ESR and CRP are also elevated. Exposure to Chlamydia trachomatis (sexually transmitted) and Chlamydia pneumonia (respiratory tract) can trigger an autoimmune response when these organisms migrate through the blood to joint tissue; this is called reactive arthritis.

With hip involvement, ultrasound shows marked distention of the hip joint with varying degrees of femoral hip displacement. Septic arthritis is an emergency situation, and treatment must be initiated immediately.

Gout Gout is a joint inflammation caused by deposits of urate crystals and is associated with an inborn error of uric acid secretion or with metabolic disorders (e.g., hemolytic anemia, renal insufficiency, sarcoidosis). Men older than 30 years and those with a family history of gout are most often affected. The patient reports a recurrent, sudden onset of pain early in the morning that subsides over several days, especially of the first

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metatarsophalangeal joint. The joint is warm, tender, and red; tophi (chalky subcutaneous deposits of sodium urate) may be present on extensor surfaces. Gout can be differentiated from pseudogout by the presence of calcium pyrophosphate crystals, involvement of large joints, and secondary osteoarthritis. Laboratory findings during an acute attack show elevated serum uric acid level, ESR, and WBC count. The joint may be aspirated for fluid to observe uric acid crystals and cultured to exclude septic arthritis.

Musculoskeletal pain related to trauma or overuse

Hip and leg

Slipped capital femoral epiphysis In children undergoing a rapid growth spurt, the onset of knee pain, an antalgic limp, and leg weakness may indicate a slipped capital femoral epiphysis (SCFE). Pain may be of several weeks’ or months’ duration and is exaggerated by strenuous physical activity. Examine the child in a prone position and assess the symmetry of medial rotation of the hip. A reduction of medial rotation may indicate an SCFE. A widening of the epiphyseal plate can be visualized in a lateral view radiograph.

Transient synovitis of the hip A nonspecific inflammatory condition of the hip, transient synovitis is the most common cause of a painful hip in children younger than 10 years. History may reveal a recent upper respiratory tract infection or minor injury. The child complains of pain in the anteromedial aspect of the thigh and knee and walks with an antalgic limp; there is tenderness on palpation over the anterior aspect of the hip joint. Hip movement is limited and painful. There may be a low­grade fever. Ultrasound should be used for diagnosis, and both hips should be compared. WBC count is usually normal, although the ESR may be elevated.

Legg-calvé-perthes disease This disease occurs as osteochondritis of the femoral head epiphysis. It is characterized by a period of avascular necrosis of the femoral head, followed by revascularization and bone healing. It occurs most commonly in boys between the ages of 3 and 11 years. The child has groin or medial thigh pain and a limp. The pain may be recurring, and the child may have been limping for several months. The loss of medial hip motion is an early sign. There is a high incidence of hernia, undescended testicles, and kidney abnormalities in children with this condition. Radiographs show the ossific nucleus of the femoral head combined with the widened articular cartilage space compared with the opposite hip.

Iliopsoas tendinitis This tendinitis is caused by frequent repetitive flexion of the hip joint and is common in weight lifters, rowers, and football players. The patient complains of mildly intense groin pain on the anterior hip, which worsens with movement. An acute injury involves forced extension of a flexed leg. In younger age groups, radiographic evaluation is done if evulsion of the epiphysis is suspected. Test for iliopsoas tendinitis by having the seated patient place the heel of the affected leg on the knee of the other leg. This movement will create pain and a tense iliopsoas muscle (Table 22.2).

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Table 22.2 Selected Tests Used to Assess for Lower Extremity Musculoskeletal Disorders

TEST DESCRIPTION

LEG OR HIP

Positive test result is a mushy or soft end feel when tibia is moved forward, indicating damage to anterior cruciate ligament.

Medial bulge will appear if fluid is in knee joint.

Tests for cruciate ligament stability; abnormal anterior or posterior movement of tibia on femur is a positive drawer sign and indicates ligamentous instability.

Pain and a palpable or audible click are positive findings and indicate a meniscus injury. Positive finding in this position

indicates a lateral meniscus injury. Positive finding in this position

indicates a medial meniscus injury.

Foucher sign

Bulge sign

Drawer sign

Apply medial or lateral pressure when knee is flexed 30 degrees and when it is

Medial or lateral collateral ligament sprain

extended. will show laxity in movement and no solid end points, depending on degree of sprain.

Lachman test (cruciate ligaments)

Iliopsoas Have seated patient place heel of affected leg on knee of other leg.

KNEE

Look for change in consistency of a mass in popliteal fossa that hardens with extension and softens with flexion.

Apply lateral pressure to area adjacent to patella.

With patient supine, flex knee 90 degrees and hip 45 degrees with foot on table; apply slow, steady anterior pull, and in same position, gently push tibia back.

McMurray maneuver

Collateral ligament test

With knee flexed 30 degrees, pull tibia forward with one hand while other hand stabilizes femur.

With patient supine, maximally flex knee and hip; externally and internally rotate tibia with one hand on distal end of tibia; with other hand, palpate joint. Extend knee with slight lateral pressure

with tibia internally rotated. Extend knee with slight internal

pressure on tibia externally rotated.

Proximal fibula fracture

FINDINGS

Pain with this movement indicates muscle iliopsoas tendinitis.

A positive sign indicates a popliteal tumor or aneurysm; a negative sign indicates a Baker cyst.

Most proximal fibula fractures are caused by direct trauma to the lateral leg. However, some fractures can be the result of forces transferred from a lateral malleolar injury of the ankle, especially when the force is a combination of compressive and rotational trauma. The peroneal nerve and anterior tibial artery pass near the fibular head, thus injury to either of these structures can be a complication of a proximal fibular fracture. If foot drop is present or a diminished dorsalis pedal pulse is noted, the patient needs immediate referral to an orthopedic surgeon (Fig. 22.4).

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FIGURE 22.4 Typical appearance of a proximal fibular fracture (arrow). Source: (From Crowther CL: Primary orthopedic care, ed. 2, St Louis, 2004, Mosby.)

Stress fracture Stress fractures occur most often in the weight­bearing bones of the lower leg and foot. They occur in adolescents whose bodies are not able to accommodate an increase in intensity of training and in adults who engage in high­intensity exercise. Patients will note pain with activity several weeks after beginning a sport. Injury progresses from

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trabecular microfractures in the bone to the osteoclastic action exceeding the rate of osteoblastic bone formation, resulting in the bone breaking. Plain radiographs may not demonstrate injury, so MRI is used to identify location of injury and CT is used for follow­up.

Knee

Chondromalacia patellae Chondromalacia of the patella is a change in the patellofemoral joint cartilage that is most common in female adolescents. The condition can be caused by trauma, anatomic anomalies, and misalignment of the patella. Softening of joint cartilage, tufts of patellar cartilage, fissures, or ulcers occur. Patients present with anterior knee pain that is worse while climbing stairs or biking. Radiographic studies of the knee, including tangential and sunrise views, show irregularities of the patellofemoral joint.

Patellar tendinitis (Jumper’s knee) This overuse syndrome is characterized by inflammation in the distal extensors of the knee joint. Patellar tendinitis is more common in athletes who habitually place excessive strain on their knees from jumping or running. Determine the quadriceps angle by measuring the angle between the center of the patella to the anterior superior iliac spine and from the center patella to the tibial tubercle. An angle greater than 10 degrees in males and 15 degrees in females suggests patellar tendinitis. People affected complain of dull, achy knee pain that may have associated clicking or popping. Associated malalignment from femoral anteversion or ankle varus may be present.

Medial collateral ligament sprain Medial collateral ligament (MCL) injuries are common and are the result of valgus stress to the knee. The patient limps soon after the injury and may or may not have pain. On physical examination, there is mild effusion and point tenderness over the MCL. To test for stability of the medial collateral ligament, the knee is flexed about 30 degrees with the patient supine and one hand is placed over the lateral knee with the other around the ankle. Apply medial pressure to the knee while pulling the ankle outward. An instability of the MCL produces a sensation of opening the medial aspect of the joint. Applying lateral pressure in the same knee position tests for lateral ligament sprain. A radiograph is obtained to rule out fracture.

Medial meniscus tear Medial meniscus injuries, more common than lateral meniscus injuries, occur after a twisting injury to the knee. The patient has pain, difficulty flexing the knee, and difficulty bearing weight. There often is a clicking or catching in the knee joint, and the joint may be swollen and tender to palpation. To examine for medial meniscus injury, perform the McMurray test to assess for clicking, locking, or a springy end point of motion. With the patient supine, place one hand under the heel and flex the knee 90 degrees with slight abduction. Apply a lateral and medial force to the knee while extending and adducting it. A palpable or audible click indicates medial meniscus injury. The Thessaly test assesses loading forces on the knee. With the examiner and patient facing each other holding hands for support, the patient stands first on the unaffected leg and bends the knee 20 degrees while performing internal and external rotation. Pain or clicking on movement is a positive test.

Anterior cruciate ligament tear Ligaments may be stretched or torn if the knee is twisted or hyperextended. The anterior cruciate ligament (ACL), located in the center of the knee, is one of the most common ligaments damaged in knee injuries. An ACL injury is often associated with an audible pop and a giving­way sensation in the knee, often with swelling from hemarthrosis. Physical examination reveals a positive Lachman test result. With the patient supine and the knee flexed 20 to 30 degrees, and while the examiner stabilizes the femur with one hand the other hand pulls the tibia anteriorly. An intact ligament limits anterior motion. A positive Lachman test demonstrates ACL laxity.

Osgood-schlatter disease This condition, most common in adolescent males, is a painful swelling of the anterior aspect of the tibial tubercle. It is caused by strenuous activity, especially of the quadriceps

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muscles. The patient will often limp, and the pain will be worse with activities such as stair climbing and kneeling. Examination will reveal a warm, swollen, tender tibial tubercle, and flexion and extension will increase pain intensity. Joint examination of the knee is normal.

Baker cyst (Popliteal cyst) A popliteal cyst occurs when fluid from the knee joint enters the connecting bursa and becomes trapped. Patients notice fullness or swelling of the posterior knee and calf pain aggravated by walking and alleviated by rest. Examination of the knee focuses on assessment of a change in consistency of the mass on extension (hardening) and flexion (softening), called the Foucher sign. The Foucher sign is negative with a Baker cyst and positive with a tumor or popliteal aneurysm. The cyst can rupture and cause edema and tenderness of the lower extremity with a positive Homans sign, present with any condition that causes venous thrombosis. Ultrasound will detect the cyst or recently ruptured cyst.

E V I D E N C E - B A S E D P R A C T I C E

How Useful are Special Tests to Evaluate Meniscal Pathology of the Knee in an Adult? A systematic review was conducted to synthesize literature on the diagnostic accuracy of 3 special tests (McMurray, joint line tenderness, and Thessaly) to detect meniscal tears of the knee in adults. The review identified 9 studies that met criteria. Methodology quality was evaluated using the Quality Assessment Tool for Diagnostic Accuracy Studies (QUADAS) 2 criteria. Results found that joint line tenderness had the greatest sensitivity and specificity, e.g. 83% for both measures; Thessaly test sensitivity and specificity was 75% and 87%, and 61% and 84% for the McMurray test. The authors conclude that the methodological quality of the low number of studies reviewed was poor and better evidence is needed to be more clinically useful.

Reference: Smith et al, 2015.

Ankle and foot

Ankle sprain (Inversion or Eversion) The most common mechanism of ankle injury is an inversion force that stresses the lateral ligamentous support of the joint. The lateral ligaments are of greater length than the medial ligaments and are more predisposed to injury. An audible pop or tear implies a rupture or tear of the ligament. Swelling of the ankle within minutes of injury indicates bleeding and soft tissue trauma. Patients with a ligamentous injury will generally be able to walk and bear weight on the injured foot even though it may be uncomfortable. Examine the injured joint by palpating the course and attachment points of the ligaments and perform joint ROM to test for ligamentous integrity.

Shin splints (Medial Tibial Stress Syndrome) Shin splints are an inflammation of the origin of muscles on the shaft of the tibia caused by overuse, often by running athletes. Patients report achy pain and tenderness over the medial tibia that increases with exercise, especially running, and improves with rest. A radiograph of the tibia will exclude fracture.

Achilles tendinitis The gastrocnemius and soleus muscles conjoin to form the Achilles tendon. Inflammation of this tendon creates pain and swelling where the tendon inserts into the calcaneus, and a patient will report a tightness of the tendon that makes walking or running difficult. Tendinitis may be caused by overuse, especially running, or by decreased vascularity to the tendon sheath. Examination reveals tenderness over the Achilles tendon with palpation and ankle ROM, especially with dorsiflexion, crepitus over the tendon with motion, and weakness of the calf muscles.

Achilles tendon rupture

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The Achilles tendon is a strong fibrous cord that connects the back of the calf to the heel. Overstretching this tendon can lead to partial or complete (rupture) tear. It is often an injury in recreational sports. Patients will report a jumping, falling, or stepping injury and hearing a pop followed by sharp pain in the ankle and difficulty ambulating. The patient will not be able to stand on the toes with the affected limb. Ankle swelling may be present.

Plantar fasciitis Plantar fasciitis is a condition caused by chronic weight­bearing stress when laxity of foot structures allows the talus to slide forward and medially and plantar ligaments and fascia that connect the heel to the toes to stretch. Tendons and joints become inflamed, and muscles spasm because of the misalignment of structures. People who are obese or who engage in excessive standing are at greatest risk. Pain in the heel is worse on awakening and is relieved with non–weight­bearing activity.

Muscle pain (Myalgia)

Viral infections Viral infections can produce diffuse myalgias that are usually associated with fever, chills, upper respiratory tract symptoms, and malaise. A patient with influenza will have intense myalgia and a high fever and appear quite ill. Because viral illnesses are highly contagious, epidemics in both children and adults in a community may be a useful clue to diagnosis. A paraviral immunoglobulin M (IgM) titer is diagnostic of an acute parvovirus B19 infection.

Night leg cramps Leg cramps occur at night, mostly in the calf, and are relieved with flexion of the ankle, can be caused by muscle fatigue and nerve problems, although often there is no specific cause identified. Risk factors include middle­ aged adults, pregnancy, diuretics, and diabetes.

Psychogenic Pain that is diffuse, varies in pattern, and is unaffected by activity or rest may be psychogenic in origin. A careful history may reveal any secondary gain the patient may derive from the pain and suggest the presence of an anxiety or depression disorder. On examination, the patient may display facial expressions and descriptions of discomfort to palpation and movement that are inconsistent. This diagnosis involves excluding other causes.

Fibromyalgia Fibromyalgia is a syndrome characterized by chronic fatigue, generalized musculoskeletal pain, and multiple trigger points of pain on physical examination. It primarily affects women between 20 and 50 years of age, and the symptoms are worse in the morning. Other symptoms associated with this syndrome include stage IV sleep disturbance, anxiety or depression, obsessive­compulsive behavior, and irritable bowel syndrome. Symptoms are exacerbated by stress. Physical examination shows focal tenderness without signs of synovitis. Diagnostic criteria for fibromyalgia include diffuse pain present for 3 months and tenderness at 11 or more of 18 trigger points.

Systemic disorders

Acute leukemia Leukemia is the most common cancer in children, and bone and joint pain is the most common presenting complaint. The bone pain is diffuse and nonspecific and may extend to adjacent joints. Laboratory findings may show the WBC count as elevated, depressed, or normal. Severe anemia is common, as is a depressed platelet count. Radiographs of the limb at the distal end of the femur and the proximal end of the tibia show abnormal areas of radiolucency.

Sickle cell disease

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Sickle cell disease is a genetic disorder characterized by production of hemoglobin S, an anemia secondary to short erythrocyte survival, and sickle­shaped erythrocytes. It affects mainly African American, Mediterranean, and Southeast Asian population groups. Sickle cell disease manifests itself after the

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first 6 months of life. The child presents with painful or vaso­occlusive crises characterized by symmetrical, painful swelling of the hands and feet. Older people report pain in long bones and joints, abdominal pain, decreased appetite, fever, and malaise. The laboratory findings reveal a hemoglobin S genotype and anemia, but findings can vary depending on the hemoglobin genotype, age, gender, and presence of other organ involvement. Sickle cell disease is associated with osteonecrosis of the hip.

Systemic lupus erythematosus Systemic lupus erythematosus is a systemic inflammatory condition that occurs most often in women. It is characterized by arthritis that commonly involves the small joints of the hands, wrists, ankles, knees, and hips as well as malar rash, oral ulcers, glomerulonephritis, hematologic disorders, and psychological symptoms. The pain is transient but severe. Laboratory findings show leukopenia with neutrophils predominating the peripheral count, and the ANA is positive.

Lyme arthritis The bite of the deer tick may transmit the spirochete B. burgdorferi. Patients may not recall a tick bite but will have been in an endemic area. The presenting complaints in Lyme disease are diffuse joint pain and swelling, a target like skin rash (erythema migrans), fever, and chills. These symptoms may be present for weeks before the spirochete spreads via blood and lymph tissue to the myocardium and central nervous system. A chronic arthritis may appear months after the initial infection. The arthritis is asymmetrical and occurs in the large joints. The knee is a commonly affected joint. The patient has an antalgic limp with diffuse swelling and warmth of the knee joint anteriorly, as well as local synovial thickening. Laboratory diagnosis reveals elevation of IgM titers and immunoglobulin G (IgG) antibodies against the spirochete. The ESR is elevated.

Neuroblastoma Neuroblastoma is a malignant tumor that usually occurs in children younger than 5 years of age. It originates from cells in the sympathetic ganglia and adrenal medulla but can arise from any part of the sympathetic nervous system and metastasize to the bone. The presenting complaint may be varied, but bone pain, limp, pallor, and fatigue may be present. CT or MRI is used to identify the primary location of the tumor. In the urine, 3­methoxy­4­hydroxymandelic acid and homovanillic acid levels are elevated.

Osteogenic sarcoma Osteogenic sarcoma occurs in people 10 to 25 years old, with the most common site being the distal femur or the proximal tibia. The patient initially complains of local intermittent pain that quickly progresses to a constant and severe pain, and an antalgic limp may develop. Palpation reveals tenderness over the area affected. Laboratory findings show an increase in serum alkaline phosphatase level; radiograph shows a “sunburst” image.

Nerve entrapment syndromes

Peroneal nerve compression Peroneal nerve compression can be caused by a cast, sports injury, or trauma. Pain is felt across the head of the fibula and can result in footdrop.

Tarsal tunnel syndrome Tarsal tunnel syndrome is occasionally associated with motor weakness of the proximal toe flexors. The posterior tibial nerve is involved, and the pain is felt across the ankle and proximal foot. Patients may not remember a specific onset but report pain and weakness of the foot muscles. Tapping the posterior tibial nerve posterior and inferior to the medial malleolus elicits pain. Ask the patient about shoe fit and use of any orthotic devices.

Neuritis Vascular metabolism affected by systemic disorders, such as diabetes mellitus, can cause a nerve to become ischemic, producing toxins that can directly damage the nerve. Inflammation can be of the nerve axon, myelin

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sheath, or both. Soft tissue inflammation contributing to neuropathy can be caused by collagen disorders (e.g., SLE, scleroderma).

Diabetes mellitus is commonly associated with sensory peripheral neuropathy and results in pain and sensory loss that is more intense in the lower extremities.

Alcoholism is associated with distal, demyelinating neuropathy that may resolve with cessation of alcohol ingestion.

DIFFERENTIAL DIAGNOSIS OF Common Causes of Lower Extremity Limb Pain

DIAGNOSTIC CONDITION HISTORY PHYSICAL FINDINGS

STUDIES

History of systemic infection, Fever; red, swollen joint; WBC count, culture of malaise, diaphoresis, refusal limited range of motion joint aspirate, ESR, to bear weight (hip), acute CRP, ultrasound of joint pain joint

Gout

MUSCULOSKELETAL INFLAMMATION

Tenosynovitis (tendinitis)

Repetitive trauma activities; pain with movement

Swelling over tendon, crepitus

None

Bursitis History of overuse; aching pain over affected bursae that radiates along limb

Local tenderness, swelling; limited joint motion; muscle weakness

None

Osteomyelitis Presentation depends on age, location of infection; history

Fever, chills, vomiting; pain Increased WBC count,

of infection, trauma, area but progressively radiographs penetration, invasive procedure; refusal to bear

worsens; soft tissue

weight (hip); constant pain

localized over affected

injury or abscess

ESR,CRP;

JOINT INFLAMMATION

Osteoarthritis Older adults; asymmetrical joint DIP, PIP joints enlarged; ESR; radiograph may pain and stiffness that Heberden nodes; limited reveal osteophytes, improves throughout day; cervical spine ROM loss of joint space history of repetitive joint trauma; obesity

Rheumatoid Morning stiffness of small joints; Fever, rheumatoid nodules, Increased ESR, positive arthritis symmetrical involvement; ulnar deviation of wrists rheumatoid factor,

anorexia, weight loss anemia on CBC; radiograph shows bony erosion

Juvenile Fatigue, weight loss, failure to Fever, rash, guarding of Elevated WBC count, rheumatoid thrive, refusal to walk, joint joints, limited ROM; ESR; positive arthritis pain and stiffness joint swelling, nodules rheumatoid factor

and antinuclear antibody

Septic arthritis

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Acute pain of large joint, asymmetrical; men older than 30 yr of age, history of gout

Inflamed, swollen joint; tophi; sodium urate crystals

Increased serum uric acid level, ESR, WBC count

MUSCULOSKELETAL PAIN RELATED TO TRAUMA OR OVERUSE

Slipped capital femoral epiphysis

Children: During rapid growth spurts; knee pain worse with activity

Limitation of medial hip rotation, limp

Radiograph of epiphyseal plate

Transient synovitis of hip

Children younger than 10 yr; history of upper respiratory tract infection; limp, pain in anteromedial thigh and knee

Tenderness on palpation over anterior hip; hip movement increases pain and is limited; low­grade fever

Ultrasound, ESR

Legg­Calvé­ Perthes disease (LCPD)

Boys age 3–11 yr; groin or medial thigh pain, limp

Decreased hip ROM AP and frog lateral radiographs of hip; LCPD may show increased density of femoral head

Iliopsoas tendinitis

History of repetitive flexion of hip; pain worse with movement

With patient sitting, place heel of affected leg on knee of other; test is positive if pain is elicited

None

Proximal fibular fracture

History of direct trauma to the fibula or ankle

Pain on weight bearing, edema and tenderness to palpation over fracture

Radiography, CT if soft tissue injury is suspected

Stress fracture Younger age, history of overuse of lower extremities

Pain with activity Radiography, MRI

Chondromalacia patellae

Female adolescents; history of knee trauma or misalignment, knee pain worse with activity

Tenderness to palpation over knee

Four­view radiographs of knees to rule out arthritis

Patellar tendinitis History of overuse, especially running or jumping; dull, achy knee pain; click

Q angle >10 degrees in males, 15 degrees in females; clicking or popping with knee movement

None

Medial collateral ligament sprain

History of valgus stress to knee; limp; pain

Effusion and point tenderness over knee; valgus and varus pressure to assess instability

AP and lateral radiographs may reveal a ligament avulsion of femoral origin

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Medial meniscus tear

Anterior cruciate ligament tear

Osgood­Schlatter disease

Baker cyst

Ankle sprain

Shin splints

Achilles tendinitis

Achilles tendon rupture

Plantar fasciitis

History of twisting injury to the knee, pain, difficulty flexing, bearing weight, clicking or catching of knee with movement

History of twisting or extension knee injury; audible “pop”

Adolescent males; knee pain and swelling aggravated by activity, limp

Fullness or swelling of posterior knee, aggravated by walking

History of inversion stress with audible “pop,” immediate swelling

Ache or pain over medial tibia that is worse with exercise, history of running

Pain and tightness over Achilles tendon, especially with walking or running

History of a jumping, falling, or stepping injury; hearing a pop; ankle pain

History of chronic weight bearing; aching feet, muscle spasms, obesity

MUSCLE PAIN (MYALGIA)

Viral infections History of upper respiratory tract infection; malaise, chills, cold symptoms, general muscle aches

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Positive McMurray test, Thessaly test, clicking or locking during joint movement, joint tenderness

Swelling; positive Lachman test

Tenderness, warmth, swelling over anterior tibial tubercle

Negative Foucher sign; normal joint examination; positive Homans sign in ruptured cyst

Swelling, soft tissue trauma, able to perform active ROM with ligament sprain

Tenderness over medial tibia

Tenderness over Achilles tendon; pain worse with dorsiflexion ankle; calf weakness

Inability to stand on toes; difficulty with ambulation; ankle swelling

Misalignment of foot structures, especially talus, calcaneus, and plantar ligaments

Fever, ill­appearing adult or child

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Four­knee view radiographs to rule out bony abnormality; MRI

Radiograph to rule out fracture; MRI

Radiograph with knee rotated inward may show soft tissue swelling

None

Radiograph needed only with tenderness over the lateral malleolus to rule out fracture

AP and lateral radiographs may show a stress fracture; a bone scan will be positive with increased uptake along the medial tibia

Lateral ankle radiograph reveals enlarged posterosuperior tuberosity of the calcaneus

None

None

Viral serum titer

Night leg cramps

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History of night calf Normal exantination None pain or spasms relieved with foot flexion

Pain is diffuse; varies inPsychogenic Normal exantination or patient None pattern of activity, response to exantination setting; history of maneuvers disproportionate depression or to physical findings or anxiety subjective complaints

Fibrornyalgia Adult 20-50 yr; his tory Palpation of trigger points will None of depression, sleep produce pain; normal disturbance, chronic physical exantination fatigue, general muscle and joint aches

SYSTEMIC DISORDERS

Fever, hepatosplenomegaly, Acute leukemia Hip pain in children, CBC refusal to walk bruising

Hemoglobin S family history;

Sickle cell disease African American, Normal exantination genotype

appears after 6 mo of age; acute pain with swelling of hands and feet, abdominal pain, d ecreased appetite, malaise

Transient arthritis of Joint tenderness on palpation Kidney function tests, erythematosu s

Systemic lupus antinuclear

rash small joints, malar

antibody, CBC

Serum IgM and IgG endemic areas of

Asymmetrical swelling, Lyme arthritis History of exposure to warmth of joint; erythema antibodies, ESR

deer tick; chills, migrans; may have diffuse joint pain and myocardial involvement swelling; often knee is affected

Urine for pain in bones

Younger than age 5 yr; Unexplained fever Neuroblastoma vanillylmandelic or homovanillic acid; CT scan

Radiograph, serum sarcoma

Tenderness over affected areaOsteogenic Age 10- 25 yr; alkaline

lower femur, upper intermittent pain of

phosphatase tibia; limp

NERVE ENTRAPMENT SYNDROMES

Peroneal History of pressure to Unilateral footdrop None

compression knee from a cast,

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sports injury, or trauma; pain over head of fibula;

clumsy gait

Tarsal tunnel syndrome

Pain in ankle and proximal foot; weakness of toe flexors; ill-fitting shoes

Tapping pos terior tibial nerve elicits pain

None

Neuriti s Pain and sensory loss, usually of lower extremities; history of alcohol ingestion, diabetes mellitus

Decreased sensory and p ain sensation

Liver function tests, hemoglobin A1c to rule out diabetes m ellitus

AP, anteroposterior; CBC, complete blood cell count; CRP, C-reactive protein; CT, computed tomography; DIP, distal interphalangeal ; ESR, erythrocyte sedimentation rate; MRI, magnetic resonance imaging; PA , posteroanterior; PIP, proximal interphalangeal; ROM, range of motion; WBC, white blood cell.

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