More than pain: pre-operative indicators of patients who progress from unilateral to bilateral total knee arthroplasty within 10 years

Abstract

Purpose: Up to 40% of patients who seek knee arthroplasty (TKA) in the management osteoarthritis will progress to a second, contralateral TKA within 5-10 years of the index surgery. The aim of this study was to investigate whether the assessment of pain and function prior to and 12 months following the index TKA can be used to predict which patients will progress to contralateral TKA and those who do not. Methods: Five hundred and one patients were included and assessed (i) immediately prior to their first knee arthroplasty, (ii) 12 months following TKA, and (iii) 10 years (minimum 5 years) following TKA. Participant demographics (age, sex, BMI), pre-operative and 12 month post-operative self-reported pain and function scores (Knee Society Scores, Oxford-12, SF-12) and walking speed at 12 months were treated as factors that might be associated with progression to a subsequent contralateral knee arthroplasty. Factors with an association in univariate analyses (p<0.01) were entered into a binomial logistic regression using a hierarchical procedure in an order based on the strength of the association. Results: Three hundred and forty-nine participants were assessed at all three timepoints (70.0%). On average, at the time of their first TKA participants were 66.3 years old (SD=8.2) and had a BMI of 31.5 (SD=5.1). One hundred and ninety-nine participants (57.2%) were female. One hundred and forty participants reported the presence of pain in the contralateral knee at the time of TKA, and 162 participants (46.4%) progressed to contralateral TKA. Of the participants with contralateral knee pain at the time of TKA, only 84 (60.2%) progressed to contralateral TKA. Higher BMI, younger age, worse pre-operative Oxford-12 score, less knee flexion range, lower post-operative SF-12 Physical Component Score, and the post-operative presence of pain were all significantly associated with having a subsequent contralateral TKA. A binomial logistic regression model that included these factors explained between 24% and 32% of the variance in the progression to a contralateral TKA. Participants with worse pre-operative self-reported function scores were 1.2 times more likely to progress to contralateral TKA. Of the participants with no contralateral knee pain at the time of TKA, 60 (28.7%) progressed to contralateral TKA. Females in this cohort were 2.5 times more likely to progress to contralateral TKA than males, but this explained less than 8% of the variance in outcome. There was no difference in self-reported quality of life, pain or function at the latest assessment between participants who did not have a contralateral TKA (KOOS Quality of Life Average=99.7, SD=0.3; Oxford-12 score Average=37.93, SD=10.0, WOMAC Function Average 85.8, SD=17.6) and those who did (KOOS QOL Average=99.7, SD=0.3; p=0.562, Oxford-12 Average=38.3, SD=10.1; p=0.811, WOMAC Function Average = 85.9, SD=18.7; p=0.988). Conclusions: Forty-six percent of patients with TKA progressed to a second (or contralateral) TKA within 10 years. Patients with higher BMI and poorer self-reported function prior to an initial TKA are more likely to progress to the second TKA within 10 years. Females without pain in the contralateral knee at the time of the initial TKA are 2.5 times more likely to progress to the second TKA within 10 years than males with a similar presentation of pain. This information supports the need to maximise pre-operative function prior to TKA, and suggests that there are additional opportunities to tailor interventions towards preventing a second TKA surgery.