patterns in contact sports, throwing and swinging sports, running and cut- ting sports, dance and gymnastics, as well as developmental hip injuries in

pediatric athletes, are discussed. As- sessment and treatment guidelines are provided for athletes with symptom- atic labral pathology and impinge- ment, traumatic subluxations and dis- locations, chondral injuries to the hip joint, muscular contusions and strains, stress fractures, abductor injuries, snapping hip syndromes, dysplasia, the hypermobile hip, and apophyseal avul- sion injuries in pediatric athletes.

Hip Injuries in the Contact Athlete Femoroacetabular Impingement Basic Principles Femoroacetabular impingement (FAI) of the hip joint is a well-documented disorder caused by cam impingement (abnormal sphericity of the femoral head), rim impingement (an excessive anterolateral acetabular bony promi- nence), or a combination of these pa- thologies.1 FAI has been associated with injuries such as labral tears, chondral de- lamination, and osteoarthrosis.1-4

Cam-type impingement is most often seen in the young male athlete.5,6 This impingement occurs with flexion and

Dr. Kelly or an immediate family member serves as a paid consultant to or is an employee of Smith & Nephew; serves as an unpaid consultant to Pivot Medical and A2 Surgical; has received research or institutional support from Pivot Medical; and owns stock or stock options in Pivot Medical and A3 Surgical. Dr. Larson or an imme- diate family member serves as a paid consultant to or is an employee of Smith & Nephew and A2 Surgical and owns stock or stock options in A3 Surgical. Dr. Bedi or an immediate family member serves as a board member, owner, officer, or committee member of the American Orthopaedic Society for Sports Medicine and the Ameri- can Academy of Orthopaedic Surgeons; serves as a paid consultant to or is an employee of Biomimetics Therapeu- tics and Smith & Nephew; and owns stock or stock options in A3 Surgical. Dr. Zaltz or an immediate family member has received research or institutional support from DePuy. Neither Dr. Maak nor any immediate fam- ily member has received anything of value from or owns stock in a commercial company or institution related di- rectly or indirectly to the subject of this chapter.

Abstract Over the past 10 years, the understanding, assessment, and management of hip pain and injuries in the athlete have improved. Traditionally, the evaluation of hip pain and injuries was limited to obvious disorders, such as hip arthritis and fractures, or disorders that were previously considered to be simply soft-tissue strains and contusions, such as groin pulls, hip pointers, and bursitis. Two parallel tracks of progress have improved understanding of the complexities of hip joint athletic injuries and the biomechanical basis of early hip disease. In the field of sports med- icine, improved diagnostic skills now allow better interpretation of debilitating intra-articular hip disorders and their effects on core performance. In the field of hip preservation, there has been an evolution in understanding the effects of bio- mechanical mismatches between the femoral head and the acetabulum on the de- velopment of early hip damage, injury, and arthritis. The integration of these two parallel fields has accelerated the understanding of the importance of hip biome- chanics and early hip injury in human performance and function.

Instr Course Lect 2013;62:515-531.

internal rotation of the hip joint, which forces the prominent femoral head-neck junction into contact with the anterolateral aspect of the acetabu- lar chondrolabral junction. Repeated impingement results in increased shear and direct impact forces, with subse- quent intrasubstance labral tears, chondrolabral separation, chondral de- lamination, and intrasubstance labral ossification7 (Figure 1).

In contrast to cam impingement, rim impingement more commonly oc- curs in middle-aged female athletes.5,6

Rim impingement results from in- creased anterolateral acetabular over- coverage that leads to a similar reduc- tion in the functional hip flexion arc and subsequent impingement on the anterolateral femoral head-neck junc- tion. Excessive global acetabular retro- version, coxa profunda, and protrusio have also been identified as contribu- tors to this impingement mechan- ism.5,6 Resultant trauma to the ante- rior labrum and direct trauma from the femoral head contrecoup impact on the posteroinferior acetabular carti- lage may occur.5,6 Because a combina- tion of mixed cam- and rim-type im- pingements can occur, both types should be considered when impinge- ment is suspected as the etiology of hip pain in an athlete.5

Assessment The patient’s history, physical exami- nation findings, and a focused diag- nostic evaluation are used to guide management decisions and optimize treatment outcomes. The typical pa- tient with FAI reports groin pain, spe- cifically with hip hyperflexion.5 Func- tional activities of the hip, including standing from a sitting position, climbing stairs, extensive ambulation, or athletic participation, may exacer- bate or precipitate groin pain.5,6,8,9

Mechanical symptoms, including clicking, popping, and catching with hip motion, may also occur.

A focused physical examination should assess range of motion, strength, and stability of the involved hip and the contralateral asymptomatic extremity. A finding of limited internal rotation with the hip flexed to 90° is particularly important. An impingement test should be conducted using passive hip hyperflexion, adduction, and internal rotation, which re-create the most com- mon pathologic position of FAI. The test is positive if the maneuver elicits pain that is identical to that experienced with FAI. Other provocative tests also have been described to assess areas of atypical bony impingement.10,11

The diagnostic evaluation for FAI should include an AP pelvic radio-

graph and an elongated neck or modi- fied Dunn lateral view of the affected hip.12 A false profile view should be obtained if there is suspicion for con- comitant underlying dysplasia. These radiographs allow evaluation of acetab- ular version and identification of the crossover sign, in which the superolat- eral border of the anterior wall of the acetabulum can be seen intersecting or crossing over the inferomedial border of the posterior wall.13 The Dunn view allows improved evaluation of the fem- oral head-neck geometry, identifica- tion of the cam-type lesion, and calcu- lation of an alpha angle, which estimates the severity of the impinge- ment.

MRI with or without gadolinium contrast of the affected hip will allow accurate delineation of the periarticu- lar soft-tissue structures, including the femoral and acetabular chondral sur- face, labrum, capsule, and surrounding extra-articular tendinous insertions. CT with three-dimensional recon- struction and femoral version analysis provides a more detailed analysis of the proximal femoral and acetabular ge- ometry. A fluoroscopically guided, intra-articular, analgesic and steroid injection can be used as a diagnostic and therapeutic tool along with the pa- tient’s history and physical examina- tion. This diagnostic tool can be ex- tremely effective in differentiating between intra-articular and extra- articular hip pathology.

Treatment Guidelines Nonsurgical management of FAI in- cludes oral nonsteroidal anti- inflammatory drugs (NSAIDs), phys- ical therapy, and intra-articular analgesic/steroidal injections. Nonsur- gical management is often ineffective in patients with an identifiable pathol- ogy because patients with FAI are typ- ically young, active, and have a me- chanical pathology.6

Figure 1 A, Dunn lateral radiographic view of an aspheric femoral head consistent with a cam lesion. B, Intra-articular arthroscopic image of a chon- drolabral separation and a transition zone with cartilage delamination.

Sports Medicine

Surgical treatment includes acetab- uloplasty, femoral head osteoplasty, chondroplasty, labral resection, and re- pair through both open and arthro- scopic approaches.14 Arthroscopic treatment of FAI has become increas- ingly popular because it is a minimally invasive approach and provides good visualization (Figure 2). The indica- tions for choosing an arthroscopic ver- sus an open surgical approach depend on a thorough understanding of the size and location of the mechanical de- formity and the expertise of the treat- ing surgeon.

Several studies have documented excellent early results with open and arthroscopic management of FAI.15-17

Early data suggested that labral and ac- etabular rim resection achieved better results compared with labral resection alone.15 A more recent study has sug- gested that labral preservation with re- fixation and acetabular rim débride- ment may provide superior results.16

This technique is the preferred method of this chapter’s authors.

Rehabilitation and Return to Play Focused rehabilitation after open or ar- throscopic treatment of FAI will im- prove postoperative range of motion and strength and reduce pain and the time needed to return to play. The re- habilitation regimen should begin im- mediately after surgery. The patient should maintain 20-lb, foot-flat weight-bearing status with crutch as- sistance for the first 2 postoperative weeks if a femoral head-neck osteo- plasty is performed or 4 to 6 weeks if a

chondral repair including microfrac- ture is performed. Early rehabilitation should focus on maximizing passive range of motion, reducing any soft- tissue irritation, and allowing postop- erative healing of the periarticular structures. Strength training typically begins after 4 weeks, but care is taken to avoid overly aggressive protocols to minimize the risk for soft-tissue in- flammation and tendinitis. Strength, coordination, reaction time, and pro- prioception are assessed at regular in- tervals postoperatively. Return to ath- letic participation is recommended only after the affected hip approaches 90% of the condition of the contralat- eral extremity. Impact activities should not be permitted for a minimum of 3 to 4 months to allow completion of os- seous remodeling, especially after fem- oral head-neck osteoplasty.

Subluxation and Dislocation Basic Principles Posterior hip instability ranges from sub- luxation to frank dislocation. The most common traumatic mechanism of in- jury during athletic competition is a fall with a posteriorly directed force onto a flexed and adducted hip.18-20 Atrau- matic and lower energy mechanisms of hip instability also have been de- scribed.11,21,22 Hip dislocations have been reported in American football, skiing, rugby, gymnastics, jogging, basketball, biking, and soccer.11,21,22

In the athlete with FAI, the func- tional range of motion required in ath- letic competition is often greater than the limited physiologic motion al- lowed by the cam and/or pincer le- sions. Attempts to increase flexion and internal rotation can result in anterior engagement between the cam lesion and the anterior acetabulum, which le- vers the femoral head posteriorly. This levering can lead to failure of the pos- terior soft-tissue and osseous struc- tures, a posterior acetabular rim frac-

ture, and/or a posterior capsulolabral tear in addition to a crush injury to the anterior labrum18,23 (Figure 3). In certain instances, a posterior hip sub- luxation or dislocation may be the first manifestation of occult FAI in com- petitive athletes.24 Increased levering forces during athletic competition could result in hip subluxation.

Assessment Patients present with painful limita- tion of hip motion and often report discomfort in the hip when at rest. A high index of suspicion is needed to avoid missing this injury, which is often misdiagnosed as a muscle strain.11,18,19-22,25 Careful assessment of the injury mechanism is important. Although a fall on a flexed knee is the most commonly described mechan- ism, forceful impact on a hyperex- tended, internally rotated knee can re- sult in posterior hip subluxation in the athlete with underlying limited inter- nal rotation.

Unrecognized posterior subluxation of the hip with subsequent osteonecro- sis can be a devastating injury.26 The classic triad of findings after posterior hip subluxation as Moorman et al19

described in eight American football

Figure 2 Arthroscopic image showing the spherical contour of the femoral head at the head-neck junction in a patient treated with cam lesion decompression.

Video 46.1: Arthroscopic Management of Pincer- and Cam-Type Femoroac- etabular Impingement. Christopher M. Larson, MD; Rebecca M. Stone, ATC (7 min)

Sports Hip Injuries: Assessment and Management Chapter 46

players included hemarthrosis, ilio- femoral ligament disruption, and pos- terior acetabular hip fractures (Fig- ure 4). Supine AP pelvic, Dunn lateral, and Judet plain radiographs should be obtained for athletes with suspected hip subluxation. CT is help- ful in identifying small, posterior, bony acetabular hip avulsions and is also helpful in assessing underlying im- pingement or dysplasia. MRI is impor- tant for evaluating injury to the cap- sule, ligamentum teres, and labrum

and identifying loose bodies and trans- lational sheer injuries to the articular cartilage.

Treatment Guidelines In the presence of substantial hemar- throsis, fluoroscopically guided aspira- tion helps decompress the joint, re- duces pain, and may reduce the risk for subsequent osteonecrosis. Pro- tected weight bearing for 2 to 6 weeks is recommended depending on the size and location of the acetabular lip frac- ture. Early surgical intervention is re- quired if the bony fragment renders the hip unstable, if there are loose frag- ments in the central compartment that may result in third-body wear injury to the articular cartilage, or if the labrum is incarcerated in the joint, resulting in nonconcentric joint reduction. If after a course of protected weight bearing followed by progressive strengthening and attempts at a functional return to sports there is persistent pain or a sense of instability, surgery should be de- layed. If either early or delayed surgery is required, any underlying, predispos- ing structural abnormality should be treated concurrently.

Return to Play Athletes are allowed to return to play after radiographic union of the acetab- ular lip fragment and after progression to asymptomatic full strength and range of motion. A progression to sport-specific activities in a supervised environment is advised to ensure that there is no residual instability or pain.

Myotendinous Injuries About the Hip and the Pelvis Myotendinous injuries of the hip and the pelvis in athletes are increasingly being recognized. Optimal physical conditioning and full recovery from injury prior to game situations can re- duce the risk of preseason hip and groin injuries. Risks are often elevated because of the reduced schedule of off- season training. Most myotendinous injuries are treated with activity modi- fication, ice, analgesic agents, and a gradual resumption of athletic activity after the restoration of functional strength. The roles for physical therapy and platelet-rich plasma injections are evolving, but studies are lacking on their efficacy in treating acute and chronic myotendinous injuries. Some

Figure 3 A, Three-dimensional CT scan of a patient who is a lacrosse player who sustained a posterior hip subluxation with a posterior rim fracture (arrows). B, MRI scan showing injury to the posterior labrum with concomitant crushing of the anterior labrum. Arrows indicate the posterior acetabular rim fracture.

Figure 4 Arthroscopic image showing a posterior labral tear (ar- rows) with the associated bony avulsion attached to the labral frag- ment. FH = femoral head, A = an- terior, PL = posterior labrum.

Figure 5 Coronal MRI scan of the thigh of a 23-year-old man who is a National Hockey League player shows an acute proximal adductor longus rupture (arrow). The injury was treated nonsurgi- cally and resulted in return to play without restrictions.

Sports Medicine

specific injuries deserve special atten- tion.

Proximal Adductor Injuries Adductor strains are common in ath- letes who participate in cutting and pivoting sports and ice hockey. Acute injuries involving the adductor longus (Figure 5) are typically self-limiting; however, chronic, athletic-related, proximal adductor pain has been asso- ciated with underlying FAI in up to 94% of athletes.27 Chronic, recalci- trant, proximal adductor pain can be treated with surgical tenotomy, which provides pain relief and allows return to sports for most athletes. Complete proximal adductor ruptures have been reported in athletes. Although both surgical and nonsurgical treatments have been recommended, a National Football League study reported a quicker return to sports activity (6 weeks versus 3 months) after non- surgical treatment, with all patients re- turning to play regardless of the treat- ment.28

Rectus Femoris Injuries Rectus femoris strain typically results from sprinting or kicking. This injury can involve the central or the peripher- al tendon. Greater disability is re- ported with central tendon involve- ment, which can lead to a painful proximal mass that in rare instances may require surgical excision. Hetero- topic bone formation and chronic healed anterior inferior iliac spine (AIIS) avulsions can lead to subspine/ AIIS impingement (Figure 6). This in- jury can result in pain and limited hip flexion that may require decompres- sion of the AIIS. Complete proximal rectus femoris avulsions also occur. A study by Gamradt el al29 reported on the nonsurgical treatment of 11 professional athletes with proximal avulsions of the rectus femoris. All the

athletes returned to play within 6 to 12 weeks.

Proximal Hamstring Injuries Proximal hamstring strains can lead to prolonged periods of disability com- pared with middle and distal myoten- dinous injuries. Chronic proximal hamstring tendinopathy is commonly seen in distance runners. For the rare recalcitrant injury, semimembranosus tenotomy or proximal hamstring dé- bridement and repair can be consid- ered.30 Acute, complete, proximal hamstring ruptures occur infrequently but require a high index of suspicion for diagnosis (Figure 7). Patients with MRI evidence of a complete two- or three-tendon proximal rupture with greater than 2 cm retraction may bene- fit from early surgical repair to avoid long-term deficits in strength and ath- letic disability.31,32 Distal fractional lengthening and repair and, more re-

cently, proximal hamstring reconstruc- tion with allograft have resulted in im- proved strength and function for patients with symptomatic chronic proximal hamstring ruptures.31

Other Muscle Strain Injuries Although injuries can involve virtually any muscle about the hip and pelvis, some injury patterns identified on physical examination or MRI should alert the clinician to seek a secondary cause of the athlete’s pain. Signal change in the psoas adjacent to the hip capsule may indicate prior anterior hip subluxation. Signal change in the poste- rior hip musculature adjacent to the capsule may be indicative of a posterior hip subluxation. It should be recog- nized that recurrent or chronic myoten- dinous injuries about the hip and pelvis may be associated with athletic pubal- gia (also called sports hernia) or other compensatory injuries secondary to un- derlying intra-articular hip disorders.

Contusions About the Hip and Pelvis Quadriceps Contusions Quadriceps contusions typically result from a direct blow to the quadriceps muscle that crushes the deep muscula-

Figure 6 Three-dimensional CT scan of a man who is a National Football League player who previ- ously sustained a proximal rectus femoris rupture. The scan shows ossification of the rectus origin (ar- row), which resulted in subspine AIIS impingement, associated hip flexion limitations, and pain. The inset shows a two-dimensional ax- ial view of the involved hip. After arthroscopic decompression of the AIIS, the athlete returned to play without limitations or pain.

Figure 7 Coronal MRI scan of a 36-year-old patient who sustained an injury while water skiing shows a complete proximal hamstring avulsion. The avulsion was surgi- cally repaired 2 weeks after injury.

Sports Hip Injuries: Assessment and Management Chapter 46

ture against the femur. Studies have shown a decrease in disability time when patients are treated with a fo- cused knee-flexion protocol.33,34 A study of 47 naval midshipmen with quadriceps contusions showed that passively flexing the knee to 120° within 10 minutes of injury and hold- ing that position for 24 hours resulted in a mean disability time of 3.5 days.33

Aggressive stretching and heat produc- ing modalities should be avoided. The area of injury should be padded to de- crease the risk for further injury and myositis ossificans.

Hip Pointers Hip pointers result from a contusion to the iliac crest, which is protected only by a layer of subcutaneous fat. Higher-level athletes may require acute management with an anesthetic injec- tion to the iliac crest to continue sports participation in the same game or event. Padding the area until full re- covery will minimize the risk of recur- rent injury.

Morel-Lavallee Lesions Morel-Lavallee lesions can occur in athletes as degloving of the skin and subcutaneous tissue from the neigh- boring fascia, with the peritrochanteric region at particular risk.35 Initial treat-

ment with compression and cryother- apy resolves up to 50% of these inju- ries. If this treatment fails, early aspiration, with or without doxycy- cline sclerodesis, can be curative.35

Athletic Pubalgia (Sports Hernia) Definition and Presentation Athletic pubalgia or sports hernia is defined as exertional lower abdominal pain with or without associated proxi- mal adductor-related pain.36,37 Ath- letes typically present with the insidi- ous onset of increasing, exercise- induced, lower abdominal and/or adductor-related pain. The physical examination often reveals tenderness to palpation above the inguinal liga- ment over the abdominal obliques, transversus abdominis, and at the rec- tus abdominis/conjoined tendon. Pain also may be elicited over these struc- tures with resisted sit-ups. Tenderness to palpation and with resisted adduc- tion may be noted over the adductor, pectineus, and gracilis tendons.

Imaging Studies Plain radiographs may be normal in patients with athletic pubalgia or may show evidence of osteitis pubis (Fig- ure 8). Although MRI can be incon- clusive, recent studies have noted that

perisymphyseal edema, proximal adductor/gracilis/pectineus abnormal- ities, and disruptions of the rectus abdominis/adductor aponeurosis are consistent with athletic pubalgia37

(Figure 9). In some instances, intra- articular hip pathology and athletic pubalgia can coexist. Imaging studies may show findings consistent with FAI, along with intra-articular labral and chondral abnormalities.38

Differential Diagnosis The underlying pain generators associ- ated with athletic-related hip and pel- vic pain can be elusive; a multidisci- plinary approach is often required to obtain a diagnosis. Athletic pubalgia and potential underlying intra- articular hip pathology are common findings. Other differential diagnoses include psoas disorders, pudendal neu- ralgia, sciatic nerve entrapment, upper lumbar discogenic pain, pelvic and proximal femoral stress fractures, and gastrointestinal and genitourinary dis- orders. Diagnostic anesthetic injec- tions into the hip joint, pubic symphy- sis, psoas bursa, and proximal adductors/pubic cleft followed by ath-

Figure 8 A and B, Axial MRI scans showing high signal intensity in the pubis secondary to stress overload of the pubic symphysis associated with os- teitis pubis. Bone marrow edema in the pubic symphysis caused by osteitis pubis is shown in the circled areas.

Figure 9 AP radiograph of the pelvis of a 23-year-old patient who is a collegiate soccer player shows osteitis pubis (dashed arrow), ac- etabular retroversion (dotted loop), and cam-type morphology of the proximal femur (solid arrow). The patient was treated with an arthro- scopic procedure to correct FAI and concomitant athletic pubalgia/ sports hernia repair.

Sports Medicine

letic activity or physical examination can help determine the source of the disability.

Treatment Initial activity modification and a well- balanced rehabilitation program focus- ing on core stability should be imple- mented. The patient should avoid lifting heavy objects and perform low repetition, deep hip flexion weight training augmented with occasional corticosteroid injections into the pubic symphysis, adductor/pubic cleft, and hip joint. If conservative measures are unsuccessful, various surgical ap- proaches for managing athletic pubal- gia can decrease the time needed to re- turn to athletic activity.36,37 These approaches include broad pelvic floor repairs and modified hernia repairs, with or without adductor releases.36,37

FAI and Athletic Pubalgia There is increasing evidence that symptoms of athletic pubalgia can de- velop in a subset of athletes from hip joint motion limitations secondary to FAI. Studies have shown an increased incidence of chronic groin pain and osteitis pubis in athletes with limited hip internal rotation.39,40 One study reported that 94% of the athletes with long-standing proximal adductor- related pain had radiographic evidence of FAI.27 A recent biomechanical study reported increased symphyseal motion in the presence of cam-type FAI, which could contribute to the de- velopment of osteitis pubis and ath- letic pubalgia.41 In a study of athletes with both FAI and athletic pubalgia- related findings, surgical management resulted in a return to sports without limitations in 50% and 25% of the athletes after isolated FAI and sports hernia surgery, respectively.38 Surgical management of both pathologies pro- duced an 89% rate of return to sports without limitations.38 It appears that

motion limitations from FAI can lead to extra-articular compensatory pat- terns that result in athletic pubalgia in some athletes. These studies support an association between FAI and ath- letic pubalgia and emphasize the im- portance of managing both disorders in select patients to minimize the time lost from athletics and maximize suc- cessful outcomes.

Hip Injuries in the Overhead Athlete Hip pathology associated with acetab- ular labral tears in the overhead athlete is an area of growing interest in the field of sports medicine. The mechan- ics of overhead sports, particularly throwing a baseball or a football, shooting a lacrosse ball, and hitting a tennis ball, may increase the potential for labral tears associated with FAI and instability. Axial and torsional forces under loading may predispose over- head athletes to traumatic labral pa- thology. The positional requirements and movement patterns of the athlete involved in overhead sports incorpo- rate movements that can cause the bony deformities associated with FAI to abut the labrum and produce injury. These movement patterns also require excessive rotation that can lead to rota- tional instability. The labrum and cap- suloligamentous structures are at risk for injury during different phases of the overhead activity.

FAI and laxity can be linked to intra-articular hip disorders, and the abnormal mechanics caused by these deformities may lead to altered move- ment patterns in the torso and upper extremity. Although upper extremity injuries are more common than hip in- juries, pathologic stress on the torso, shoulder, and elbow may be a result of poor hip mechanics in overhead activi- ties. One study examining pitching mechanics found that shoulder and el- bow forces were substantially linked to

pelvic rotation.42 The importance of the lower extremity in generating for- ward momentum in throwing has been documented.43 If optimal stride dis- tance and lead leg foot placement does not occur because of decreased strength, restricted range of motion, pain, and/or apprehension in the lead or back hip, an overhead athlete will not properly generate torque from the pelvis and lower extremity. In pitching, leg drive is correlated with wrist veloc- ity and is responsible for approxi- mately 50% of the throwing veloc- ity.43,44 Similarly, more than 50% of the energy produced in a tennis serve is generated from the trunk and legs.45 If this leg drive does not occur, the upper extremity may be responsible for gen- erating a greater proportion of forces required for the overhead activity. The link between hip pathology, changes in movement pattern, and injury risk in the torso, shoulder, and elbow requires further study.

The basic assessment, treatment, and return-to-play guidelines for the overhead athlete with underlying hip impingement follow the previously outlined recommendations. The rec- ognition of the hip as a potential con- tributor to upper extremity dysfunc- tion in the overhead athlete should be considered in the complete evaluation of these athletes.

Hip Injuries in the Endurance Athlete Stress Fractures of the Femoral Neck and the Pelvic Ring Basic Principles Although insufficiency fractures occur in elderly patients with osteoporosis because of inadequate bone mineral density and compressive and tensile strength, stress fractures in athletes are the result of excessive, repetitive, sub- maximal stresses experienced by physi- ologically normal bone. Many factors can contribute to an athlete’s risk of

Sports Hip Injuries: Assessment and Management Chapter 46

developing a stress fracture, including bone mineral density, bone vascularity, systemic factors (hormonal status, diet, collagen abnormalities, and metabolic bone disorders), and the type of sports activity. Muscular weakness or imbal- ance may also increase the risk for a stress fracture because excessive forces are concentrated on underlying bone.

Stress fractures can affect any en- durance athlete but commonly occur in women.46 Female endurance ath- letes attempt to minimize body fat to maintain a high level of athletic perfor- mance. With decreased body fat, estro- gen levels decrease; this may lead to de- creased bone mineral density and an increased risk of stress fractures. Male endurance athletes also are at risk for stress fractures because of a similar de- crease in sex steroids (such as testoster- one).47 A decrease in testosterone re- sults in increased activity in osteoclasts and subsequent bone resorption. The combination of paradoxical bone re- sorption and repetitive excessive load- ing greatly increases the risk of stress fractures.

Assessment Patients with femoral neck or pelvic ring stress fractures typically report groin or pelvic pain that is exacerbated by weight bearing or intense activity and relieved by rest. This pain often occurs after an abrupt increase in the frequency, duration, or intensity of training, such as training for a mara- thon, a triathlon, or another endur- ance event. Patients may present with an antalgic gait. Although it is difficult to reproduce pain with palpation be- cause of the overlying soft tissue, pa- tients report pain with internal and ex- ternal rotation at the extremes of hip range of motion. In patients with sa- cral insufficiency fractures, pain is elic- ited with flexion, abduction, and ex- ternal rotation of the hip; there may be pelvic brim tenderness, but this find- ing is not sensitive because of the amount of soft tissue overlying the pel- vis. If a sacral insufficiency fracture is suspected, careful neurologic examina- tion is critical to detect nerve impinge- ment from callus formation within and around neural foramina.

The radiographic location of the stress fracture guides treatment, espe- cially with regard to the femoral neck. The location of a femoral neck stress fracture is classified as either tension sided (on the superior neck) or com- pression sided (on the inferior aspect of the femoral neck). Plain radiogra- phy is the first-line imaging modality, despite the fact that studies may be normal for 2 to 3 weeks after the onset of symptoms. Later radiographic stud- ies may show periosteal reaction, corti- cal lucency, sclerosis, or a fracture line. Initial radiographs should include AP, AP pelvis, and lateral views of the af- fected hip.

Compression-type fractures show sclerotic thickening of the inferior cor- tex of the femoral neck, often with a hazy radiolucent center. Careful corre- lation with the patient history will dif-

ferentiate this fracture from an osteoid osteoma, which may have a similar ra- diographic appearance. Tension-sided fractures appear as transverse and lu- cent and are perpendicular to the supe- rior aspect of the femoral neck. The pelvis may be evaluated for contralat- eral hip pathology as well as stress frac- tures of the pelvic ring and sacrum. In- let and outlet views of the pelvis may be used to evaluate the pelvic ring and sacrum.

Although nuclear imaging has been used in the past with success, axial im- aging modalities are currently favored as the studies of choice after plain radi- ography.48 With focal symptoms such as hip and groin pain, MRI can be used to directly evaluate the area of in- terest. MRI is advantageous because it can be used to rule out other differen- tial diagnoses, including soft-tissue ab- normalities. On MRI, stress fractures have decreased signal intensity on T1- weighted images and increased signal intensity on short tau inversion recov- ery and T2-weighted images (Fig- ure 10).

Treatment Guidelines Prior to treating the stress fracture lo- cally, global abnormalities must be ad- dressed. These include hormonal and nutritional deficiencies and the evalua- tion of connective tissue disease if clin- ically warranted. Activity modification is the mainstay of treatment for stress fractures of the femoral neck and the pelvis.

In compression-sided stress frac- tures of the inferior femoral neck, the bone is inherently stable and nonsurgi- cal treatment is used. Displacement of compression-sided femoral neck stress fractures is extremely rare. Activity modification (with or without protect- ed weight bearing) and expectant man- agement are usually successful. Con- versely, a tension-sided stress fracture should raise clinical concern because

Figure 10 A coronal short tau inversion recovery image of the hip of a 45-year-old- woman with right hip pain 2 weeks after running a 5-km race shows increased signal intensity (arrow). This signal inten- sity pattern is consistent with an early-stage stress reaction fracture.

Sports Medicine

the biomechanical forces causing dis- traction at the fracture site increase the risk for the development of a displaced femoral neck fracture, with the possi- ble complications of osteonecrosis, varus malunion, delayed union, and nonunion.49 Initial management with internal fixation may avoid complica- tions. Radiographic displacement is an indication for urgent percutaneous fix- ation with cannulated screws (Fig- ure 11). Patients are typically managed with protected weight bearing for up to 12 weeks, which is guided by the resolution of symptoms and radio- graphic signs of healing.

Most patients with sacral and pelvic ring stress fractures are treated nonsur- gically. Activity modification and close follow-up are the mainstays of treat- ment.

Rehabilitation and Return to Play The patient’s symptoms and radio- graphic signs of healing guide the full return to athletic activity. In patients with low-risk stress fractures about the hip and pelvic ring (compression-sided femoral neck, pelvic ring, and sacrum fractures), activity should be adjusted to attain a pain-free level for 4 to 8 weeks and is dependent on the sever- ity of the symptoms and the injury. Crutches can be used for comfort, but weight bearing may be done as toler- ated in uncomplicated injuries. As symptoms improve, patients can prog- ress to light, low-impact physical activ- ity and then to full activity if pain con- tinues to decrease. This typically takes 3 to 6 weeks with low-grade lesions and up to 16 weeks with high-grade le- sions.50

After patients with high-risk stress fractures (tension-sided fractures of the femoral neck) are stabilized surgically, they may return to play after symp- toms have completely resolved and there is no pain with provocative ex- amination maneuvers or with activi-

ties.51 Follow-up radiography is typi- cally helpful to assess hardware placement and radiographic healing.

Abductor Failure Basic Principles Hip abductor musculature is attached to the greater trochanter of the femur in a fashion analogous to the attach- ment of the rotator cuff to the shoul- der. Acute and chronic injury to the gluteus medius and gluteus minimus can cause failure and tearing of the tendon insertions similar to that of a rotator cuff tear. These clinical entities, along with recalcitrant trochanteric bursitis, are referred to as greater tro- chanteric pain syndrome and have a peak occurrence between the fourth and sixth decades of life. This syn- drome is four times more common in women than in men. Often, the initial pathology occurs in the tendinous in- sertions on the greater trochanter, with secondary involvement of the adjacent bursae because bursal distension is uncommon.52-54

Assessment On presentation, patients report lateral hip pain centered over the greater tro- chanter. Occasionally, a patient may

report a specific injury or a pop; how- ever, this injury may also be chronic. Groin pain indicates a separate pathol- ogy that requires evaluation of the intra-articular pathology. On physical examination, patients typically report tenderness to palpation of the greater trochanter and either pain-limited or true weakness of the hip abductors de- pending on the size of the tear.

Although plain radiography is the initial study of choice to rule out os- seus pathology, the diagnosis of abduc- tor failure is largely based on MRI and ultrasound findings. In those with in- tractable greater trochanteric pain syn- drome, 45% to 50% of patients have gluteus medius tendon tears demon- strated by MRI or ultrasound.53,55 On MRI, these tears have high signal in- tensity on T2-weighted sequences and intermediate signal intensity on T1- weighted sequences (Figure 12).

Treatment Guidelines Although most patients with greater trochanteric pain syndrome respond to

Figure 11 Fluoroscopic image of two percutaneous screws placed in the femoral neck of a 45-year-old patient who is a runner with a tension-sided stress fracture.

Figure 12 Coronal MRI scan of a high-grade tear of the anterolat- eral band insertion of the gluteus medius tendon (arrow) with adja- cent soft-tissue edema. The glu- teus minimus tendon is moderately degenerated.

Sports Hip Injuries: Assessment and Management Chapter 46

conservative management, recalcitrant pain is often caused by gluteus medius or minimus tendon tears. Surgical treatment may be considered if non- surgical management (activity modifi- cation, physical therapy, and oral NSAIDs) for a minimum of 6 months is unsuccessful.

Both open and endoscopic surgical techniques have been described with good to excellent results in most pa- tients.56 Similar to rotator cuff repair in the shoulder, the tendon and foot- print insertion may be débrided and repaired using suture anchors (Fig- ure 13). In a prospective study of 10 patients treated with arthroscopic ab- ductor repair with a minimum 2-year follow-up, all patients had complete resolution of pain in the lateral hip. Nine of the 10 patients (90%) had complete return of abductor strength based on manual muscle testing, 1 re- gained 80% abductor strength, and all of the patients maintained full hip range of motion. At 1-year follow-up, modified Harris hip scores and hip outcome scores normalized to 92 and 93 points, respectively.57-59 All of the patients reported normal or nearly normal subjective hip function.60

Massive abductor tears with retrac- tion are rare in this patient cohort and

require open repair with tissue mobili- zation. Irreparable massive tears may be reconstructed with flap transfer of the gluteus maximus or allograft re- construction.61

Rehabilitation and Return to Play Postoperative rehabilitation after en- doscopic repair consists of 6 weeks of crutch-protected weight bearing with 20 lb of pressure on the operative ex- tremity. An abduction brace is used for 6 weeks to protect the repair from acci- dental trauma and stress. Gentle pas- sive range of motion begins 1 week postoperatively, progressing to active range of motion and abductor strengthening at 6 weeks. Twelve weeks postoperatively, strengthening continues and sport-specific activities begin at 16 weeks. Running is allowed after abductor strength equals that of the unaffected side and is followed by full clearance for return to play.60 A similar algorithm can be used for open repairs after surgical wound healing is stable. Return to play after nonsurgical management is guided by improve- ment in the patient’s symptoms and begins with targeted physical therapy, strengthening, and progression of ac- tivities as tolerated.

Dysplasia and the Unstable Hip Basic Principles Understanding hip instability associ- ated with dance and gymnastic sports illustrates the complex range of hip in- stability that may be related to specific maneuvers and exacerbated by acetab- ular and femoral malformations. Dance and gymnastic sports involve a complex combination of movements requiring extreme maximum, repeti- tive transverse, coronal, and sagittal plane range of motion. Passive range of motion data gathered from a large co- hort of classic ballet dancers suggest that there is loss of hip motion with age that requires compensatory lumbar motion. This age-related motion loss may lead to increased stress on the hip in end motion.62 Recent data suggest that certain motions, even in normal hip joints, produce leverage between various parts of the upper femur on ei- ther the acetabular rim or pelvis. Ex- periments with professional dancers using motion capture analysis showed femoroacetabular translation when the hip reached terminal motion.63,64 Un- derlying acetabular malformations and variations in upper femoral morphol- ogy have an effect on the mechanical consequences of dance and gymnastic- like activities. Increased femoral ante- version or anterior acetabular hypopla- sia can lead to increased strain within the acetabular labrum, especially when the hip is positioned repetitively in ex- ternal rotation and abduction.65 In- creased strain is placed on the labra of dancers and gymnasts with mild un- derlying acetabular dysplasia who re- petitively load the hip in exten- sion.66,67

Assessment Hip pain associated with activities sim- ilar to gymnastic sports or dance is challenging to diagnose and treat. The

Figure 13 A, Arthroscopic image of a gluteus medius tear off the lateral facet with two suture anchors placed to restore the natural footprint. B, Arthro- scopic image of the repair of the gluteus medius tendon with two double- loaded 5.5-mm peak anchors.

Sports Medicine

objective of the clinical and radio- graphic assessment is to establish the hip joint as the source of pain because soft-tissue injuries associated with re- petitive activity are prevalent in this group of patients. It is important to obtain a careful history beginning with the onset of pain and the precipitating factors, the character of the discom- fort, the location of the symptoms, the type of mechanical symptoms (such as locking, catching, crepitus, and insta- bility), activity tolerance, and the tran- sition of pain (such as flexion to exten- sion, or pain with increased intra- abdominal pressure). It is also important to identify patients with atypical pain patterns, such as those with night pain, genital pain, or associ- ated neurologic symptoms.

The objective of the physical exam- ination is to characterize the mechani- cal characteristics of the hip joint and attempt to identify the anatomic struc- ture that could be generating pain. Careful palpation of the hip region is used to identify inflamed structures. Passive motion testing and assessment of femoral torsion assists in under- standing the motion limitations of the hip. Neurologic testing can identify specific patterns of weakness or spine- related problems that are associated with hip dysfunction.68 Provocative tests are performed to identify specific patterns of activity-related instability.

Plain radiography, MRI, or CT is used to unify a suspected diagnosis and characterize the hip joint anatomy (Figure 14). Specific patterns of hip deformity are identifiable on radio- graphs by measuring the anterior and lateral center-edge angles, the acetabu- lar depth-width ratio, the Tönnis an- gle, and the orientation of the acetabu- lar walls. Less specific findings associated with hip instability include an increased neck-shaft angle, a high fovea, eversion of the epiphysis, and sclerosis of the lateral acetabular

sourcil. CT can supplement plain ra- diographic information, whereas MRI is helpful in characterizing labral mor- phology and associated labral and ar- ticular cartilage damage that may be present inside the hip joint.

Treatment Guidelines An incremental therapeutic approach should be used to treat patients en- gaged in repetitive athletic activities that produce hip instability with subtle anatomic deformity. The approach be- gins with a period of activity modifica- tion that ranges from complete rest to modified exercise and is combined with a course of anti-inflammatory medication and exercises to strengthen abdominal and pelvic muscles that may have weakened. The specific movements that precipitated the me- chanical abnormality should then be identified, and efforts should be made to modify these mechanics to alleviate symptoms. The use of intra-articular cortisone may be considered for se- lected patients for diagnostic and ther- apeutic purposes. If nonsurgical ther- apy fails and the athlete continues to have athletic-related pain or daily dis- comfort, surgical treatment should be considered.

The goal of surgical treatment is to correct the underlying mechanical ab- normality that is contributing to pain generation. Because the correction of hip instability most often involves ac- etabular reorientation, special care must be taken during surgery to limit motion loss after femoral head cover- age is increased. Some surgeons have reported using capsulorrhaphy to sta- bilize subtly unstable hip joints, but there are few data on outcomes.69

Patients who do not respond to nonsurgical treatment can elect acetab- ular reorientation. Athletes with bor- derline hip dysplasia present a chal- lenging treatment dilemma with respect to simply managing intra-

articular pathology versus corrective osteotomies.

Return to Play Patients usually can return to play if the pain resolves following a period of rest and education to correct the movements causing the mechanical abnormality or after successful surgical treatment. In either circumstance, re- turn to play is not recommended until adequate hip abductor strength is achieved. The patient should return to play in a graduated fashion and in a structured, supervised environment.

The Hypermobile Hip Without Dysplasia Basic Principles There is no accurate definition of a hy- permobile hip, although the term is used frequently, especially in female athletes with ligamentous laxity who present with hip pain. The term should be used diagnostically only when all other potential causes of pain are excluded. Anatomic entities that are often present in patients with liga- mentous laxity include torsional ab- normalities such as femoral antever-

Figure 14 Radiograph showing a mildly dysplastic hip joint in a fe- male patient who is a dancer. Impingement-related hip instability was seen when the hip was placed in maximum flexion and external rotation.

Sports Hip Injuries: Assessment and Management Chapter 46

sion, subtle acetabular dysplasia, psoas tendinitis, and central (core) muscle weakness.70,71 Generalized ligamen- tous laxity, which is usually defined us- ing the Wynne-Davies criteria, may re- late to subtle activity-dependent instability72 (Figure 15).

Assessment The assessment of a patient with hip pain begins with a careful history, physical examination, and radiograph- ic evaluation. Because hip pain associ- ated with ligamentous laxity is diag- nosed after excluding all other potential structural deformities that can produce pain, it is often necessary to use high-resolution MRI and CT to evaluate for labral and chondral dam- age and femoral and tibial torsion. Pa- tients also should be evaluated for signs of connective tissue disorders, such as Marfan and Ehlers-Danlos

syndromes. Diagnostic injections may be necessary to determine if intra- articular anesthesia can relieve the pa- tient’s symptoms.

Treatment Guidelines It is challenging to treat patients with hip pain with ligamentous laxity if there is no identifiable structural de- formity. Often, the patients have asso- ciated symptoms of bursitis that should be treated with a course of NSAIDs or that may respond to ap- propriate injections. Physical therapy to strengthen lower abdominal, paraspinal, and pelvic hip muscles can relieve some discomfort. There is a very limited role for surgical treatment in hip pain associated with ligamen- tous laxity. Occasionally, when a pa- tient responds appropriately to an intra-articular injection, an arthro- scopic examination is considered.

When performing arthroscopy, it is es- sential to perform a minimal capsulot- omy and repair or, in some instances, plicate the capsule when complete.73

Return to Play It is safe for the athlete to return to play if there is satisfactory relief of symptoms following a period of rest, therapy, or surgery. Muscle strength should be sat- isfactory to help prevent future injuries, and return to play should be gradual, with an emphasis on modifying body mechanics to prevent reinjury.

Pediatric Hip Injuries in Sports

Apophyseal Avulsion Injuries Basic Principles The human hip and pelvis develop from a single mass of mesenchymal tis- sue that forms the upper femur and the entire pelvis. The ilium, ischium, and pubis comprise the pelvis and ac- etabulum. Toward the end of skeletal maturation, the femoral and pelvic apophyses become recognizable radio- graphically and include the lesser tro- chanter, the greater trochanter, the pu- bis, the ischial tuberosity, the iliac crest, the anterior superior iliac spine, and the AIIS. The apophyseal plate is composed of columnar-arranged chondrocytes located between primary and secondary sites of ossification where muscles either originate or in- sert. Pelvic and upper femoral avulsion injuries most commonly occur during adolescence;74 however, they can occur until the mid-20s when the iliac apo- physes fuse. These injuries often occur with an eccentric muscle contrac- tion.75 The ischial tuberosity and the AIIS are the two most commonly avulsed apophyses76 (Figure 16). Se- vere complications after avulsion inju- ries are rare, with femoral head necro- sis reported after greater trochanteric avulsion.77

Figure 15 Illustrations of the five signs of ligamentous laxity described by Wynne-Davies. A, Elbow extension. B, Thumb touching forearm. C, Knee extension. D, Ankle dorsiflexion. E, Metacarpophalangeal joint extension. (Adapted with permission from Wynne-Davis R: Acetabular dysplasia and fa- milial joint laxity: Two etiological factors in congenital dislocation of the hip. J Bone Joint Surg Br 1970;52(4):704-716)

Sports Medicine

Assessment The diagnosis of an avulsed apophysis is usually straightforward. Athletes experi- ence a sudden injury, often accompanied by a popping sensation, which is accom- panied by pain that can interfere with weight bearing. Physical findings in- clude limitation of motion, swelling, and tenderness. Radiographic examina- tion is necessary to confirm the diagno- sis of an avulsion injury and exclude concomitant pathology. In rare in- stances, CT may be necessary to accu- rately gauge the degree of avulsion.

Treatment Guidelines Pelvic avulsion injuries are usually self- limiting disorders that heal without specific orthopaedic intervention. If weight bearing is painful, crutches can be used. Acutely, ice and NSAIDs are useful at reducing pain and swelling. Rarely, a displaced ischial tuberosity or iliac crest avulsion injuries may require surgical fixation. The decision to repair an avulsion with surgery depends on the magnitude of the avulsion and the potential for the development of symp- tomatic weakness, nonunion, or a pain- ful exostosis at the site of healing.

Return to Play As with other minor avulsion fractures, patients can return to play after the in- jury has healed and the athlete has re- gained his or her preinjury level of flex- ibility and strength.

Slipped Capital Femoral Epiphysis and Developmental FAI Basic Principles Upper femoral deformity is associated with symptomatic FAI and labral dis- ease. The pathogenesis of the deform- ity was considered akin to the develop- ment of a slipped capital femoral epiphysis (SCFE), with posterior translation of the epiphysis leading to prominence of the anterolateral femo- ral metaphysis and a pistol grip defor- mity. Anthropologic and radiographic evidence suggest distinct etiologies of SCFE and cam-type upper femoral morphologies. Despite a similar radio- graphic appearance at skeletal matu- rity, the pathoanatomy is different. The anatomy and mechanics of SCFE is well understood. Weakness of the upper femoral physis leads to anterior translation of the metaphysis relative to the neck of the femur. Although there is anatomic variability related to slip chronicity, the epiphysis remains normally shaped but abnormally aligned. In contrast, cam-type mor- phology will likely develop slowly de- pending on the morphology of the up- per femoral chondroepiphysis. When the trochanteric apophysis and upper femoral epiphysis are coalesced, persis- tent epiphyseal tissue localized to the anterolateral and lateral femoral neck form an aspheric extension of the fem- oral head78,79 (Figure 17).

Assessment Hip pain that is caused by FAI or chronic SCFE is usually localized to the groin, the peritrochanteric area, the buttock, or the thigh and may be

associated with mechanical symptoms. Usually, a patient with a slipped epiph- ysis has a history of SCFE treatment. Occasionally, there is no history of a childhood diagnosis of SCFE. Radio- graphically differentiating between cam-type morphology and mild, healed, chronic SCFE can be difficult using an AP radiograph; however, a lateral radiograph will show anterior metaphyseal translation that is not present with a cam-type femoral neck.

Treatment Guidelines Treatment depends on the patient’s history, degree of discomfort, and MRI appearance of the articular carti- lage. Surgical decision making is de- pendent on the shape and orientation of the femoral neck as well as the ex- tent of gait disturbance. Treatment op- tions include arthroscopic osteoplasty or open femoral neck osteoplasty, which is usually performed through a surgical dislocation. Intertrochanteric osteotomy may be required to com- pletely address the deformity.

Return to Play Patients are permitted to return to play

Figure 16 Three-dimensional CT scan showing the anatomy of ischial and AIIS apophyses, which are the two most common apophy- seal avulsion fractures.

Figure 17 Radiograph showing coalescence of an adolescent tro- chanter and upper femoral epiphy- sis, which has been associated with the development of cam-type morphology.

Sports Hip Injuries: Assessment and Management Chapter 46

after the hip pain resolves. For those with excessive arthrosis who are not surgical candidates, pain is managed conservatively, and sports participation is dependent on the patient’s symp- toms. After surgery, patients are per- mitted to return to sports participation after sufficient time has passed to per- mit healing, and muscle strength is normal. All patients are advised to avoid maximum hip flexion to prevent irritation to the acetabular rim.

Summary The parallel developments in the as- sessment and treatment of hip injuries in the subspecialties of orthopaedic sports medicine and hip preservation have resulted in a more sophisticated understanding of the etiology of symp- tomatic hip pathology. The clear rela- tionship between mechanical mal- alignment in the hip and the subsequent development of labral and chondral injury and extra-articular in- jury can be magnified in the setting of athletic activity because of the in- creased load on the joint during sports participation. In many instances, the earlier detection of hip injuries allows more timely and effective treatment. A thorough evaluation of the mechanism of injury, a detailed physical examina- tion, and accurate interpretation of ra- diographic and advanced imaging studies are essential in the workup of an athlete with hip pain. Although sur- gical outcomes continue to improve with better techniques, continued em- phasis on patient selection and the ap- propriate treatment of the underlying intra-articular pathology and struc- tural malalignment are necessary for further advancements.

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Sports Medicine

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Video Reference 46.1: Larson CM, Stone RM: Video.

Arthroscopic Management of Pincer- and Cam-Type Femoroac- etabular Impingement. Edina, MN, 2011.

Sports Hip Injuries: Assessment and Management Chapter 46

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