Risk factors for knee instability after total knee arthroplasty surgery

Objective To screen and evaluate the risk factors for knee instability after total knee arthroplasty on. Methods Clinical data of 136 patients who was diagnosed with knee osteoarthritis and underwent unilateral total knee arthroplasty in our department during January 2015 and December 2018 were collected and analyzed retrospectively. They were divided into knee stability and instability groups according to their conditions before and in 1 year after surgery. Knee pain and dysfunction grades of Western Ontario and McMaster Universities Arthritis Index (WOMAC), stair-climbing power, 25-meter straight-line walk time, and knee range of motion were recorded and statistically analyzed. Results Among the 136 cases, 77.9% had preoperative knee instability, and 20.6% of them retained instability in 1 year after surgery. The subjects with retaining knee instability after surgery had significantly serious WOMAC pain and activity limitations compared to the patients without instability (7.1±3.4 vs 3.0±2.5, 18.9±11.2 vs 8.4±8.6, P < 0.01). Multivariate prediction model analysis predicted that comorbidity score (>6 points) (P < 0.01), low stair climbing power (< 150 W) (P < 0.01), moderate-severe pain (>7 points) (P < 0.01) and older age (>60 years) (P < 0.01) were independent risk factors for persistent knee instability after surgery. Conclusion Knee instability has a high incidence before and after total knee arthroplasty and is associated with the potential risk factors of knee pain, activity limitation and stair climbing power.