Summary

Effects of preoperative knee contracture on functional outcomes

Abstract

Introduction

One of the primary issues conducting a primary total knee arthroplasty is the management of a native preoperative flessum, usually associated with poor post-operative knee function. Our study aimed to assess the functional results of a primary TKA using a standardized algorithm to manage pre-operative flessum.

Methods

A retrospective single center case-control study was conducted from January 2000 to December 2016 at the Orthopedic Surgery Department of the Lyon University Hospital. Were included all consecutive patients with a pre-operative flessum superior to 10° and were randomly selected controls with a 1-4 cases ratio. Knees were assessed pre- and post-operatively using the Knee Society Score (KSS).
Level of significance was set at p<0.05.

Results

849 cases and 3305 controls were included, 2839 men and 1315 women. The mean pre-operative extension deficit was 13.22° [10-55] for the flessum group and 0° [-5:9] for the control group. Pre-operative KSS knee score and KSS function score were significantly inferior in the flessum group (41.5 ± 18.2 and 55.3 ± 20) than in the control group (53.8 ± 15.8 and 59.3 ± 19.5) (P< 0.0001). After TKA, analysis between flessum group and control group found respectively no significant difference for the KSS function score (76.9 ± 23.1 vs 78.5 ± 21.8, P=0.168), but a statistical difference in the KSS knee score (87.2 ± 12.3 vs 88.1 ± 12.9, P=0.003). Moreover, a significant difference was found regarding post-operative KSS pain subscore (45.1± 8.2 vs 43.9 ± 9.6, P=0.015), post-operative knee extension deficit (1.2 ± 3.1 vs -0.3 ± 1.7, P<0.0001), post-operative maximum knee flexion (114.4 ± 13.9 vs 118.9 ± 13.5, P<0.0001).

Conclusion

A standardized and systematic algorithm to manage pre-operative knee flessum in TKA procedures showed statistically different but clinically similar outcomes than TKA for patients without pre-operative knee flexion contracture.