Why do patients not kneel after total knee replacement? Is neuropathic pain a contributing factor?

Abstract

Despite kneeling being an important and valued function of the knee, a proportion of patients are unable to kneel following arthroplasty. We explore the reasons for this, and assess whether neuropathic pain is a contributing factor. In this observational study, data was collected prospectively for 134 knees. At one year follow-up, patients completed a semi-structured questionnaire, the Oxford Knee Score (OKS), and the painDETECT score. Ability to kneel was assessed by question 7 of the OKS. Change in kneeling ability was assessed using Wilcoxon signed-rank test, normal data with independent t-test, and a regression and ANOVA analysis performed to assess predictors of kneeling ability. 88% of patients had tried kneeling post-operatively. There was no change in kneeling ability for the whole cohort from pre- to post-operatively (p = 0.313). Patient reasons for not kneeling varied. Male gender, younger age and a reduced pain score were all significantly associated with a greater ability to kneel postoperatively. There was a trend towards an improved ability with increased flexion. Mean pain scores for all kneeling abilities lay within the nociceptive rather than neuropathic range. Kneeling ability varies greatly post-knee replacement, and is multifactorial. Greater pain is a contributing factor to the inability to kneel postoperatively, but this appears to be nociceptive rather than neuropathic in nature.