Attention Should Be Paid to the Bone Mineral Density Status of Patients Undergoing Unicompartmental Knee Arthroplasty: A 1,164-Case Follow-Up Study.

Abstract

Osteoporosis is a systemic skeletal disorder, which can compromise implant fixation strength and increase the risk of postoperative complications. Currently, the relationship between the abnormal bone mass and clinical outcomes following unicompartmental knee arthroplasty (UKA) remains unclear. A retrospective review was conducted on follow-up data from 1,164 patients who underwent UKA, who had a mean follow-up period of 32 months (range, 28 to 41). Bone mineral density (BMD) was measured and osteoporosis was diagnosed according to World Health Organization criteria. Among participants, 734 patients (63.1%) had normal BMD, 314 (27.0%) had osteopenia, and 116 (9.9%) had osteoporosis. Demographic and clinical data, including age, sex, body mass index (BMI), and length of hospital stay, were recorded. Postoperative functional outcomes were assessed using validated scoring systems: the Knee Society Score (KSS), Oxford Knee Score (OKS), Visual Analog Scale (VAS), and Forgotten Joint Score (FJS). The prevalence of osteoporosis was significantly higher in women than in men (P = 0.005). The BMD was positively correlated with BMI (P < 0.001) and negatively correlated with age (P < 0.001). Postoperatively, all groups showed significant improvement in knee function (P < 0.001). However, the osteoporosis group exhibited significantly lower KSS clinical scores (P < 0.001) and higher VAS scores (P = 0.004) than the normal group. Additionally, the osteoporosis group had significantly lower postoperative KSS functional scores and FJS than both the osteopenia and normal groups (P < 0.001). Among osteoporotic patients, those who had mobile-bearing prostheses achieved significantly better outcomes in KSS functional scores (P = 0.007) and FJS (P = 0.026) than those who had fixed-bearing prostheses. Low BMD adversely affects the clinical outcomes of UKA, and patients who had osteoporosis demonstrated significantly poorer postoperative functional recovery. For osteoporotic patients, the use of mobile-bearing prostheses is more highly recommended.