Surgical Site Infection After Total Knee Arthroplasty : A Descriptive Study
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SurgicalSiteInfectionAfterTotalKneeArthroplasty.docxSurgical Site Infection After Total Knee Arthroplasty : A
Descriptive Study
Sadik Bilgen1, Gokay Eken2
1Assoc. Professor, Department of Orthopedic Surgery, Uludag University School of Medicine, Bursa, Turkey
2Chief Assistant, Department of Orthopedic Surgery, Uludag University School of Medicine, Bursa, Turkey
Abstract— Joint replacement operations which are applied to reduce the pain and increase the
movement capacity are among the surgical procedures that are used mostly nowadays. Even though a
dramatic recovery is seen in the life of the patient after total knee prosthesis, possible prosthesis
infection increases cost and causes high morbidity. This study was conducted with the aim to determine
rates of surgical site infection after performing primer total knee prothesis operation in our clinic.
Furthermore, it has been intended to understand risk factors which may cause infection and then take
precautions. This study was conducted from January 2008 to January 2013, 252 knees underwent
primary total knee arthroplasty operations. Among these patients infection rates, relationship to risk
factors and infection treatments were analysed. It was observed that iIn 252 knees, 10 (4%) superficial
infections were found, debridement and antibiotics were applied to 3 knees out of 10 and only antibiotic
treatment was applied to the rest 7 knees. Deep infection was detected in 4 knees (1,6%) out of 252.
Acute deep infection in 1 knee and recovery was provided with debridement and intravenous antibiotics
treatment. Late deep infection was not detected in any of patients. Delayed deep infection was detected
in 3 (1,1%) of these knees though. Among all risk factors only increased body mass index showed
increased superficial wound infection rate. It can be concluded that among the factors like rheumatoid
arthritis, diabetes, age, gender, body mass index, just body mass index has an impact on superficial
infection rate. Our infection rates were comparable to rates mentioned in universal literature for
primary total knee replacement operations.
Key words: Joint replacement, Surgical site Infection, Arthroplasty
I. INTRODUCTION
With the aging population, joint diseases are seen more often today. Pain and limitation of movement
ability in these diseases occur and with joint injury over time decrease life quality of the patients
considerably. Therefore, joint replacement operations which are applied to reduce the pain and increase
the movement capacity are among the surgical procedures that are used mostly now a day. Even though
a dramatic recovery is seen in the life of the patient after total knee prosthesis, possible prosthesis
infection increases cost and causes high morbidity. According to the research applied in a number of
different centers, 0,5%-5% infection rates have been reported after primer total knee arthroplasty. 1,2.3
Infection mechanism takes place through direct transmission of disease or haematogenous. Some
examples of direct transmission are unclean operating theatres, transmission from an infected patient,
usage of torn surgical gloves, negligence of the operating staff about sterility and these cases can be
taken under control. Transmission through haematogenous occurs following bacteremia. For instance,
Streptococcus viridans or peptostrepotococcus after dental intervention, staphycoccusspecies after skin
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infections and gram negative enterococcusand anaerobic infections after gastrointestinal genitourinary
infections can be experienced. 4
Swelling, pain and decrease in functional capacity at the knee joint occur following knee arthroplasty
and as the infection progresses, periarticular bone stock decreases and implant loosenings. Patients who
are not treated sufficiently may experience sepsis and life threatening septic shock. In addition, it has
been reported that infected knee prothesis prolongs the duration of hospital stay and increases the cost
considerably. 5
In this research, it has been aimed to determine rates of surgical site infection after performing primer
total knee prosthes is operation in Uludağ University Medical Faculty Orthopedics and Traumatology
Clinic. Furthermore, it has been intended to understand risk factors which may cause infection and then
to take specific precautions.
II. METHODOLOGY
A Hospital based descriptive type of observational study was conducted on patients of primary total
knee arthroplasty operations which were performed in Uludağ University Medical Faculty Orthopaedics
and Traumatology Clinic between the years of 2008-2013 have been studied retrospectively. All
medical computer records of the patients who had the operation have been scanned. 252 total knee
arthroplasty operations were performed on 206 patients. All these 206 cases were taken into
consideration for study.
Posterior stabilised Sigma® (Depuy-Johnson ve Johnson, Warsaw, ABD) total knee prosthesis was
applied to all patients. Patients with severe collateral ligament injury were not included in the study.
Average length of follow-up was 26,8 (24-85) months. All of 252 knees were followed more than 24
months.
Descriptive statics for categorical variables were given with frequency and corresponding percentage
values. Data showing congruity with normal distribution, T test for independent samples and Mann-
Whitney U test for data showing incongruity with normal distribution were applied in comparison
among groups. Chi-square (Pearson Chi-Square), Fisher’s exact chi-square test (Fisher’s Exact Test) and
Fisher-Freeman-Halton Test were applied for qualitative variables. Statistical significance in this study
was defined as p = 0.05, statistical analyses were performed using SPSS software V.21 .
Relationships between infection, diabetes mellitus, body mass index, age, gender, length of hospital stay,
type of anaesthesia procedure, surgery side of body were analysed. Comorbidities of the patients,
besides diabetes mellitus, were also studied. The correlation between prosthesis infections and diseases
such as hypertension, asthma bronchiale, hypothyroidism, Behçet disease, coronary artery disease,
haemophilia was studied. For this Charlson Comorbidity Index that was described before calculated for
each patient and assessed the relationship between infection rates.6 At this index, certain scores were
given for each diseases according to severity. Sum of the scores were calculated for the patients that
have multiple diseases. Scoring system is described as; 0 point mild, 1-2 point moderate, 3-4 point
severe, more than 5 point very severe.
Definitions:The infection was diagnosed taking many different factors into account. Firstly, clinical
findings (fever, erythema, discharge etc) were taken into account. From imaging methods, while
radiolucency or osteolysis was observed via X-ray, intake increased around prosthesis and infection was
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diagnosed via bone scans and indium-labeled white blood cell scans. In bacteriological research,
infection was diagnosed with culture reproduction transmitted during surgery, blood cultures and
arthrocentesis. During the operation, histological examination can support the diagnose.7 Also,
unhealthy granulation tissue, synovitis, bone destruction (osteoporosis) and loosening of the prosthesis
lead to infection again.
While infections which include skin and subcutaneous layer were referred as superficial infections,
infections which include bone and prosthesis were referred as deep infections. Time between surgery
and infection was also classified. Accordingly, acute deep infection was defined as an infection which
occurs in the first 4 weeks and could be treated with debridement and intravenous antibiotics,7 delayed
deep infection was defined as an infection which occurs after 4 weeks but within 2 years of TKR, late
deep infection was defined as an infection which occurs after 2 years and is thought to originate from
haematogenous.3
Preoperative Preparation: With the aim of septic focus scan, ear-nose- throat examination was carried
out for all patients scheduled for surgery; for female patients, clinical examinations were made by
gynaecologists, urologists and dentists. White blood cells, sedimentation, c-reactive protein levels were
tested. Urinalysis and urine culture tests were performed. During all these examinations and tests, as
soon as an infection situation was experienced, knee prosthesis surgery was cancelled and the patient
were excluded from the study.
Patients were trained by the doctors, nurses and physiotherapists. With intend to use the prosthesis
healthfully for life and to prevent late prosthesis infection, patients were informed to prevent septic
lesion from progression. All patients who complied with the training were taken into operation and
included in research. Anaesthetists evaluated the patients' suitability to the operation and informed them
about anaesthesia.
Peroperative Prophylactic Applications: All operations were performed in the operating room with
vertical laminar air flow unit. Air flow was 5253m3 per hour. Air exchange rate was 29,2m3 per hour.
Temperature was fixed to 20°C and humidity was fixed to 60% in the operating theater. Microbiological
air sampling was performed 3 times, including the last one in 2014. Bacteria count was zero in all these
samples.
Sterile waterproof clothing and double-layer orthopaedic gloves were used in all operations. All lower
limb was painted 3 times from the tourniquet and draped. After drape application, top layer gloves were
thrown. Following the induction of anaesthesia, each patient was given 1 g of cephalosporin
intravenously with the purpose of prophylaxis before the tourniquet was applied. In the following 24
hours after surgery, 3 more doses of 1 gr cephalosporin were given intravenously.
Data thus collected on a semi structured, pre designed schedule were entered in Microsoft Excel sheet to
prepare master chart, tabulated and analysed to get inferences.
III. RESULTS
All medical computer records of the patients who had the operation have been scanned. 252 total knee
arthroplasty operations were performed on 206 patients with mean aged 66.7years and range 29-
93Years. Out of these 206 cases, 167 (81%) of whom were female and 39 (19%) of whom were male.
(Figure 1)
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Out of these 252 knee arthroplasty, 233 (92.5%) had osteoarthritis, 18 (%7.1%) had rheumatoid arthritis
and 1 (0.4%) had haemophilic arthropathy. (Figure 2)
Bilateral total knee arthroplasty operations were performed on 38 (22.7%) of female patients and
8(20.5%) of male patients at different sessions. It shows that bilateral was performed on about 1 patient
out of 4. This difference sex wise not found significant. (Figure 3)
All types of infections, microorganisms which were identified as active, operation years and treatments
were explained in Table -1.
Figure 1 Figure 2
Figure 3
In 252 knees, 10 (4%) superficial infections were found, debridement and antibiotics were applied to 3
knees out of 10 and only antibiotic treatment was applied to the rest 7 knees. It was seen that all of them
had total recovery and had no complaints in their last controls. (Table 1)
Deep infection was detected in 4 knees (1,6%) out of 252. Acute deep infection which occured two
weeks after the operation was detected in 1 knee and recovery was provided with debridement and
intravenous antibiotics treatment. No infection findings were detected in the last control. (Table 1)
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Late deep infection was not detected in any of the 252 knees which have been followed more than 2
years. Delayed deep infection was detected in 3 (1,1%) of these knees after 4 weeks, within 2 years. In 1
patient out of these 3, as the result of the culture which was sent from the applied arthrocentesis material
showed lack of growth, debridement and intravenous antibiotics treatment were applied and total
recovery was assured; the other two patients had swelling in the knee and complaints about pain in the
48th and 28th weeks after the first operation and as a result of methicillin sensitive staphylococcus growth
from the applied arthrocentesis material, two-stage knee prothesis revision surgery was applied and both
patients had a full recovery at last control. (Table 1)
Table 1
Distribution of study subjects as per type of Infection and Treatment
S. No.
Infection
Operation
Year
Microorganism
Treatment
1
Superficial Infection
(N=10)
2010
No Growth
Oral Antibiotics
2011
MRSH
IV And Oral Antibiotics
2011
No Growth
Oral Antibiotics
2011
No Growth
Oral Antibiotics
2012
MSSA
Debridement and IV Antibiotics
2012
No Growth
Debridement and IV Antibiotics
2012
Morganella
Debridement and Oral Antibiotics
2013
No Growth
IV Antibiotics
2013
No Growth
IV Antibiotics
2013
No Growth
IV Antibiotics
2
Acute Deep Infection
(N=1)
2013
No Growth
Debridement and IV Antibiotics
3
Delayed Deep Infection
(N=3)
2008
MSSA
2 – Stage Revision and Antibiotics
2013
MRSA
2 – Stage Revision and Antibiotics
2013
No Growth
Debridement and IV Antibiotics
4
Late Deep Infection
(N=0)
None
-
-
(ab: antibiotic, iv: intravenous, mrsh: methicillin-resistant staphylococcus haemolyticus, mssa:
methicillin-sensitive staphylococcus aureus, mrsa: methicillin-resistant staphylococcus aureus)
While superficial infection was detected after total knee arthroplasty in 10 knees (4,9%) out of 205 of
female patients, 47 of male patients did not experience superficial infection but that difference is not
statistically significant (p=0,216). When the relationship between patient age and infection frequency
was examined, no significant correlation was found. (Table 1)
Osteoarthritis was most commonly seen arthritis type which results knee arthroplasty (92,5%).
Romatoid artrit was found in 7,1% of the knees and haemophilic arthropathy was found 0,4%,
respectively. When the correlation between arthritis etiology and infection was examined, it was seen
that before arthroplasty, osteoarthritis was present at all knees which had infection; nevertheless, no
statistically meaningful correlation between arthritis etiology and infection was found (p = 0.450). 51
patients 62 knees (24,6%) with diabetes, and 155 patients 190 kness (75,4%) wihout diabetes were
found. When the knees of the patients with diabetes were examined, 3 knees (4,8%) had superficial
infection, 2 knees (3,2%) had deep infection; as to patients wihout diabetes, 7 knees (3,6%) had
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superficial infection, 2 knees (1,1%) deep infection but the correlation between either infection types
and diabetes was not found statistically meaningful (p=0,976, p=0,546). (Table 1)
The mean body mass index of the patients was detected as 33.5 (obese). While the mean body mass
index of the patients who had superficial infection was 39,6. Also it was 33,2 in patients who had no
superficial infection. That difference was statistically significant (p=0,001). While the mean body mass
index of the patients who had deep infection was 37,5 and it was 33,4 in patients who had no deep
infection. That diffence was not statistically significant (p=0,191). (Figure 4 & 5)
Figure 4 Figure 5
Length of hospital stay was assessed for each patient and mean duration was found 7 (3-27) days.
Patients that had superficial infection were 8,5 (5-20) days. Also patients that had not superficial
infection were 7 (3-27) days. Patients with and without deep infection mean hospital stay were found
same and 7 days. This difference in hospital stay was not found significant (p>0.05).
There was no significant difference between these parameters like surgery time, types of anaesthesia,
and surgery side and Charlson Comorbidity Indexes for superficial and deep infections
IV. DISCUSSION
This present study observed that after total knee arthroplasty, deep infection rate was found 1,6%. When
the literature was examined, infection rates after total knee arthroplasty vary between 1-2%.8,9 While
Peersman and his friends reported infection rate as 1,45% after total knee arthroplasty, Fan and his
friends reported infection rate as 1%.10,11 Taking precautions to prevent infection after arthroplasty is
easier than infection treatment. For this purpose, preoperative routine systemic infection scans and
treatment of possible infection sources before the operation decrease rates of infection after arthroplasty.
Preoperative prophylactic antibiotic treatment is applied to prevent infections. Accumulated haematoma
during postoperative period enables us to obtain bactericidal effects. In the literature, the most common
two microorganisms which are isolated in infection after total knee arthroplasty are reported as
Staphylococcus aureus and Staphylococcus epidermidis.10,12,13 It is a known fact that first generation
cephalosporins among Staphylococcus species are quite effective. We also used intravenous cefazolin as
a routine in preoperative infection prophylaxis in our study. In our study, 14 knees had infection, 5 out
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of them had culture reproduction, MSSA in 2 knees, MRSH in 1 knee, MRSAin 1 knee and Morganella
strains in 1 knee were isolated.
It is reported that vertical laminar air flow among the other infection precautions decreases infection
rates after operation significantly. Postoperative infection of than other measures used were reported to
significantly reduce infection rates. In a study which was conducted by Lidwell and his friends14 it is
seen that vertical laminar airflow decreases the amount of particles of the surgery room from 164 CFU /
m3 to 2 CFU / m3. On the other hand, in a study which was conducted by Brandt and his friends,15 it is
reported that laminar air flow does not decrease infection rates after arthroplasty. In another study which
was conducted by Bloom and his friends,16 a significant decrease is reported in infection rates along
with antibiotic prophylaxis, well patient cover, vertical laminar air flow. In our study, low infection rates
were obtained trough vertical laminar air flow, double orthopedic gloves use, proper purification and
cover techniques, microbiological air sampling at regular intervals.
When risk factors after total knee arthroplasty are studied, in the literature diabetes were shown as a
main reason frequently. Yang and his friends16 found deep infection rate as 5,5% in 109 knees with
diabetes. England and his friends17 found deep infection rate as 7% in 59 knees. In our study, 8% of the
patients with diabetes and 4, 7% of the patients without diabetes had infection. However, there is not a
significant difference. That situation contradicts with the information in the literature. When rheumatoid
arthritis, another risk factor, is examined in the literature, it was reported that it increases postoperative
infection rates.18,19 In our study, none of the patients with rheumatoid arthritis had infection and there
was no significant correlation between arthrosis etiology and infection.
V. CONCLUSION
Primary total knee arthroplasty infection rates can be kept low when necessary preoperative, intra-
operative and postoperative infection precautions are taken into account. It is found that among the
factors like rheumatoid arthritis, diabetes, age, gender, body mass index, just body mass index has an
impact on superficial infection rate. This means that when body mass index increases, superficial
infection rate also increases. Our infection rates were comparable to rates mentioned in universal
literature for primary total knee replacement operations.
CONFLICT
None declared till date.
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