Influence of the Intraoperative Extension Gap on Postoperative Flexion Contractures in Total Knee Arthroplasty

Abstract

Objective: In patients undergoing total knee arthroplasty (TKA), removing preoperative flexion contractures is crucial. We analyzed the relationship of preoperative and postoperative flexion contractures with the extension gap during surgery.

Methods: We examined 100 knees which had undergone TKA (FINE^® Total Knee System CR) using the “pre-cut technique” at least six months previously. We measured flexion contractures before surgery and five days and six months postoperatively. Extension gaps were measured after setting the pre-cut trial and trial components.

Results: The flexion contracture was 10.3±7.9° (0-40°) before surgery and 3.1±3.6° (0-20°) and 2.6±3.2° (0-13°) at five days and six months postoperatively, respectively. The extension gap on the pre-cut trial and trial components was 8.0±2.6 (3-15) mm and 11.6±1.1 (10-17) mm, respectively. In some cases, flexion contractures were worse (>5°) at six months than at five days. It was apparent that preoperative flexion contractures were the only significant exacerbating factor. In cases with a large preoperative flexion contracture angle, soft tissue balance was significantly adjusted to enlarge the extension gap. In the cases of soft tissue balancing, preoperative flexion contractures in cases with exacerbation were significantly worse than in non-exacerbation cases; preoperative flexion contracture angles were<20° in most non-exacerbation cases, but>20° in approximately half of the exacerbation cases.

Conclusion: In patients undergoing TKA, if preoperative flexion contracture angles are>20°, a solution strategy should be considered.