Original Article
Infection After Knee Arthroplasty: A Prospective Study of 1509 Cases

https://doi.org/10.1016/j.arth.2007.05.052Get rights and content

Abstract

We report a prospective study of 1509 consecutive total knee arthroplasties looking at risk factors for infection in modern surgical practice. The overall deep infection rate was 1%. A further 51 patients had a superficial infection (3.3%). Statistical analysis revealed no correlation between risk of infection and age and sex. Those who had poor health as assessed by the American Society of Anesthesiologists score had no increased risk of infection. Neither did patients undergoing arthroplasty for rheumatoid arthritis. Diabetic patients and those with morbid obesity (body mass index, >40 kg/m2) had an increased odds ratio for deep and superficial infection, but these results did not reach statistical significance.

Section snippets

Materials and Methods

Prospective data were collected on 1509 consecutive knee arthroplasties performed in our unit in 1349 patients. There were 160 bilateral cases. Data were collected between October 1998 and February 2005.

Patients were reviewed 7 to 10 days preoperatively by an audit nurse at a preassessment clinic. Age, sex, body mass index (BMI), and medical history including diabetes were recorded. American Knee Society scores (AKSS) and the 12-item Short Form Health Survey (SF-12) were used. Patients were

Results

Of the 1509 cases, there were 1390 PFC Sigma (DePuy) TKAs performed through a standard medial parapatellar approach. The patella was resurfaced in only 35 cases (2.5%). The remaining 119 cases were Oxford (Biomet) unicompartment knee arthroplasties.

Follow-up data were available for the majority, with greater than 90% of patients attending follow-up appointments (Table 1).

The overall deep infection rate was 1% (16 cases). The commonest infecting organism was coagulase-negative Staphylococcus in

Discussion

Deep infection after knee arthroplasty is a rare but serious complication with revision often being the end result. Blom et al [6] looked at deep infection rates in 471 primary knee arthroplasties. They found that 7 (77.8%) of their 9 cases of deep infection resulted in revision. A number of patient-related factors have been suggested to increase the risk including hemophilia, diabetes, rheumatoid arthritis, obesity, and poor nutritional state. Many of these reported risk factors are, however,

Conclusion

Using modern orthopedic surgical techniques, we found the infection rate for TKA is not increased in rheumatoid arthritis. A high ASA grade does not increase the risk of infection. Diabetic patients and patients with a BMI greater than 40 kg/m2 have a higher infection rate, which did not reach clinical significance. Superficial infection rarely progresses to deep infection and can be safely treated with appropriate antibiotics, with a good expectation of success.

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  • Cited by (82)

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    No benefits or funds were received in support of the study.

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