Factors associated with lateral skin numbness and improvement after total knee arthroplasty in Samuthprakarn Hospital

Abstract

Objectives: This study aimed to identify factors that contribute and improve post-operative lateral skin numbness after total knee arthroplasty at Samuthprakarn Hospital between January 1, 2019 and December 31, 2021.

        Materials and Methods: An analytical case-control study was conducted using the ratio of cases to controls 1:2. The correlation was analyzed with Chi-square or Fisher's exact test (in case more than 20% of the total cell counts have an expected value less than 5). The size of the association was then analyzed performing the crude odds ratio (OR) and 95% confidence interval (95%CI). The statistical significance was 0.05.

        Results:  For single-variable correlation factors (Univariate analysis) affecting lateral numbness after knee replacement, it is found that family members or caregivers made 0.23 times improvement in knee lateral numbness (95%CI 0.09-0.62) P-value 0.003. For multi-variable correlation factors (Multivariate analysis) affecting lateral numbness after knee replacement, 8.31 times the risk of lateral knee numbness after knee replacement surgery (95%CI3.07-22.46) was found in those spending  11 days or more of hospital stay. During 6 weeks to 3 months after surgery, inability to walk without a cane or pain in about 200 meters, but self-help developed 15.55 times risk (95%CI 2.38-101.25) P-value 0.004. After 3 months, lack of movement, frequent flexion or extension around the operative knee caused 5.88 times risk (95%CI 1.28-26.90) P-value 0.022. Having bedroom on the 2^nd floor of the house made 65.45 times risk of lateral knee numbness (95%CI 1.29-3319.03) P- value 0.037.