Department of Orthopaedic Surgery, Singapore General Hospital, Singapore, Singapore.
J Arthroplasty. 2018 Mar;33(3):718-722. doi: 10.1016/j.arth.2017.10.046. Epub 2017 Oct 31.
There is often an assumption by patients that weight loss will occur once their knee pain is relieved by total knee arthroplasty (TKA). This study aims to evaluate (1) the change in patients' body mass index (BMI) after TKA; (2) if postoperative change in BMI influences functional outcome and survival rate of TKA; and (3) the predictive factors associated with change in BMI.
Seven thousand seven hundred thirty-three patients who underwent a primary TKA between 2001 and 2010 were included in this study. Functional outcome scores collected at 2 years after surgery include the Oxford Knee Score, Knee Society Function Score, Knee Society Knee Score, Physical Component Score, and Mental Component Score of short form 36.
Among these patients, 1067 (14%) had reduction in BMI, 5045 (65%) maintained their BMI, and 1621 (21%) had gain in BMI. The differences in improvement in Oxford Knee Score, Knee Society Function Score, Knee Society Knee Score, and Physical Component Score among the 3 groups of patients were less than the known minimal clinically important difference of these scores. The 10-year survival rate of TKA was not influenced by patients' change in BMI after surgery (P = .435). Obese class I, II, and III patients were more likely to reduce their BMI after TKA than those with normal preoperative BMI (P = .002, P = .012, and P = .004, respectively), while older patients were less likely to have gain in BMI after surgery (P = .001).
A change in BMI after TKA did not influence the functional outcome clinically or the survival rate of the TKA implant.
患者常常认为全膝关节置换术（TKA）可缓解膝关节疼痛，体重也会随之减轻。本研究旨在评估：（1）TKA 后患者体重指数（BMI）的变化；（2）术后 BMI 的变化是否影响 TKA 的功能结果和生存率；（3）与 BMI 变化相关的预测因素。
本研究纳入了 2001 年至 2010 年间接受初次 TKA 的 7733 例患者。术后 2 年收集的功能结果评分包括牛津膝关节评分、膝关节学会功能评分、膝关节学会膝关节评分、简短 36 项健康调查量表的生理成分评分和心理成分评分。
这些患者中，1067 例（14%）BMI 降低，5045 例（65%）BMI 维持不变，1621 例（21%）BMI 增加。3 组患者的牛津膝关节评分、膝关节学会功能评分、膝关节学会膝关节评分和生理成分评分的改善程度差异均小于这些评分的已知最小临床重要差异。TKA 的 10 年生存率不受术后患者 BMI 变化的影响（P=0.435）。肥胖 I 级、II 级和 III 级患者 TKA 后 BMI 降低的可能性大于术前 BMI 正常的患者（P=0.002、P=0.012 和 P=0.004），而年龄较大的患者术后 BMI 增加的可能性较小（P=0.001）。
TKA 后 BMI 的变化不会影响 TKA 植入物的功能结果或生存率。
