Obesity may increase revision risk among patients undergoing TKR for OA
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Published results showed a higher risk of all-cause revision and revision for infection among patients who were obese and undergoing primary total knee replacement for osteoarthritis compared with patients who were not obese.
Using the Australian Orthopaedic Association National Joint Replacement Registry, Christopher J. Wall, MBBS, BMedSc, FRACS, FAOrthA, and colleagues compared the rates of all-cause revision and revision for infection, loosening, instability and pain between patients who were not obese (BMI of 18.50 kg/m2 to 29.99 kg/m2), patients with class 1 and class 2 obesity (BMI of 30 kg/m2 to 39.99 kg/m2), and patients with class 3 obesity (BMI of 40 kg/m2 or greater) who underwent primary TKR for OA from Jan. 1, 2015, to Dec. 31, 2020. Researchers adjusted results for age, sex, tibial fixation, prothesis stability, patellar component usage and computer navigation use.
Among the 141,673 patients who underwent primary TKR for OA in Australia during the study period, researchers identified 2,655 revision procedures for infection (39.7%), loosening (14.8%), instability (12%) and pain (6.1%). Results showed a higher risk of all-cause revision and revision for infection among patients with class 1 and class 2 obesity compared with patients who were not obese. Researchers found a higher risk of all-cause revision after 1 year, revision for infection after 3 months and revision for loosening among patients with class 3 obesity vs. patients who were not obese. All groups had similar risks of revision for instability and pain, according to results.
“As the majority of patients undergoing knee replacement are obese (58% in our previous paper), these findings raise concerns for a growing burden of revision knee replacement in the future,” Wall told Healio. “There is an urgent need to address obesity at a societal level in order to reduce the burden of obesity-related knee OA, primary TKR and subsequent revision TKR.”
References:
Wall CJ, et al. ANZ J Surg. 2022;doi:10.1111/ans.17689.
Wall CJ, et al. J Bone Joint Surg Am. 2022;doi:10.2106/JBJS.21.01491.
Perspective
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Despite the well-known limitations of registry data, this study evaluating the relationship between obesity and implant survivorship presents valuable findings for arthroplasty surgeons. The authors analyzed a large cohort from the Australian Orthopaedic Association National Joint Replacement Registry between 2015 and 2020. Importantly, adjusted analyses were performed to control for implant factors, such as tibial fixation, which has been recognized as a potential confounder especially in patients with a BMI of 35 kg/m2 or greater based on discrepancies in recent literature on cemented and cementless TKA. The authors noted that all-cause survivorship was significantly poorer in class 3 patients compared with class 1 and 2 patients and was poorer in class 1 and 2 patients compared with patients who are not obese. While this might seem plausible, it is important to note that an aggregated endpoint (ie, all-cause survivorship) may be skewed by its individual components, notably, the rate of revision for infection. Given the numerous confounders for infection risk, such as diabetes, kidney disease and immunosuppression –– all of which are highly correlated with obesity–– the conclusion that obesity of any class is associated with increased risk of revision for infection is largely unsupported, although morbid obesity has been consistently identified as a risk factor for this complication. For this reason, the findings by Christopher J. Wall, MBBS, BMedSc, FRACS, FAOrthA, and colleagues should be interpreted with caution.
References:
Abdel MP, et al. J Arthroplasty. 2015;doi:10.1016/j.arth.2015.06.057.
Goh GS, et al. J Arthroplasty. 2022;doi:10.1016/j.arth.2021.12.038.
Jämsen E, et al. J Bone Joint Surg Am. 2012;doi:10.2106/JBJS.J.01935.
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