Mylène Jansen

54 Chapter 3 Prediction of nine-year clinical survival A larger initial increase in minimum JSW was found to be a positive predicting factor for survival of the native knee joint both uncorrected (HR 0.28 (95%CI 0.11–0.72); p= 0.008) and corrected for baseline (0.05 (0.01–0.58); p= 0.016). A larger increase in mean cartilage thickness showed a higher incidence of survival when corrected for baseline as well (0.21 (0.02–0.76); p= 0.025). Male sex was positively associated with survival (0.24 (0.06–1.00); p= 0.050). For all data see Table 2. Table 2 : Crude and adjusted Cox regression analyses displaying the influence of baseline and 1-year change characteristics on undergoing total knee arthroplasty Crude hazard ratio Adjusted hazard ratio HR P- value HR P- value Baseline Age 1.04 (0.90–1.20) 0.586 Male sex 0.24 (0.06–1.00) 0.050 BMI 1.12 (0.91–1.34) 0.286 Kellgren-Lawrence grade 1.08 (0.34–3.43) 0.894 WOMAC total 1.00 (0.95–1.05) 0.976 VAS pain 1.03 (0.94–1.12) 0.568 Mean MAC JSW 0.82 (0.49–1.35) 0.424 Minimum JSW 0.82 (0.43–1.56) 0.550 Bone density 0.92 (0.79–1.08) 0.322 Mean cartilage thickness 0.78 (0.26–2.34) 0.663 Denuded bone area % 0.99 (0.96–1.03) 0.666 Initial (First-year) changes ΔWOMAC total 1.02 (0.98–1.05) 0.356 1.03 (0.98–1.07) 0.288 ΔVAS pain 1.01 (0.98–1.03) 0.692 1.01 (0.99–1.04) 0.408 ΔMean MAC JSW 0.71 (0.36–1.40) 0.321 0.31 (0.09–1.04) 0.058 ΔMinimum JSW 0.28 (0.11–0.72) 0.008 0.05 (0.01–0.58) 0.016 ΔBone density 1.13 (0.96–1.33) 0.143 1.12 (0.90–1.38) 0.312 ΔMean cartilage thickness 0.31 (0.06–1.62) 0.164 0.12 (0.02–0.76) 0.025 ΔDenuded bone area % 1.01 (0.98–1.06) 0.476 1.03 (0.96–1.11) 0.414 Hazard ratio (HR) and 95% confidence interval are given. Significant p- values (<0.05) are in bold. BMI: body mass index; JSW: joint space width; MAC: most affected compartment; VAS: Visual Analogue Scale; WOMAC: Western Ontario and McMaster Universities Osteoarthritis Index. Discussion Nine years after KJD treatment, nearly half of the patients still had no joint prosthesis, even though they were originally indicated for TKA. Survivors reported still significantly increased clinical scores 9 years post-KJD. Moreover, the minimum JSW as a measure for cartilage thickness was still increased compared to pre-treatment values 7 years post-treatment in these patients. Interestingly, patients who underwent TKA in the years after KJD reported increased clinical scores at last follow-up as well; compared to survivors’ 9-year parameters, there was