The relationship between body mass index and clinical efficacy of knee arthroplasty in patients with knee osteoarthritis

BACKGROUND: Increase body mass index (BMI) is often accompanied by metabolic diseases such as diabetes, which will increase the uncertainty of total knee arthroplasty (TKA) efficacy and the risk of postoperative complications. The present study was to study the relationship between increase BMI and clinical efficacy of knee arthroplasty in patients with knee osteoarthritis. METHODS: A total of 97 patients (36 males and 61 females) with knee osteoarthritis (KOA) who underwent TKA surgery were selected. According to the preoperative body mass index (BMI), the patients were divided into a normal group (n=42), overweight group (n=35), and obese group (n=20). All patients received TKA after admission. Seven days after surgery, the American Knee Society (AKS) and the Hospital for Special Surgery (HSS) scales were used to evaluate the recovery of knee function. The recovery was poor if the scores of AKS and HSS were less than 70. RESULTS: Seven days after TKA, the scores of AKS and HSS in different BMI groups were significantly different, and decreased with the increase of BMI (P<0.05). Age, increased BMI, diabetes, preoperative range of motion (ROM), intraoperative blood loss, postoperative C-reactive protein (CRP), postoperative posterior slope angle (PSA), postoperative infection, and postoperative deep vein thrombosis (DVT) of lower extremities were related to AKS score <70 (P<0.05). Diabetes, preoperative ROM, intraoperative blood loss, postoperative CRP, postoperative PSA, and postoperative infection were related to HSS score <70 (P<0.05). Increased BMI, diabetes, postoperative CRP, postoperative infection, and postoperative DVT were independent risk factors for AKS score <70 (HR =3.458, 1.152, 2.960, 1.023, 3.589, P<0.05). Increased BMI, diabetes, postoperative CRP, and postoperative infection were independent risk factors for HSS score <70 (HR =6.891, 1.263, 1.967, 1.235, P<1.235). The area under the curve (AUC) (95% CI) of BMI in diagnosing AKS <70 was 0.740 (0.641–0.839). The AUC (95% CI) of BMI in diagnosing HSS <70 was 0.809 (0.723–0.894). CONCLUSIONS: The increase of BMI is an independent risk factor for the poor recovery of knee function after TKA in patients with KOA.