Soft tissue balance is known to be an important factor for the success of Total Knee Arthroplasty (TKA). Traditional surgical techniques involve soft tissue releases and bony cuts to achieve the correct balance. Evaluation of balance is currently based on subjective intraoperative clinical assessment, or the “feel” of the knee. More recently, an instrument to objectively measure soft tissue balance following bony cuts has been developed. Soft tissues releases using this instrument may be extensive.

Hypothesis. The hypothesis is that patients who undergo more extensive releases will have poorer short-term outcome and increased complication rates compared to those who undergo less extensive releases.

Method: 506 patients aged 40–90 years underwent 526 Kinemax TKAs, performed by seven surgeons in five centres between October 1999 and December 2002. Five surgeons used traditional methods for soft tissue balancing and two were guided by the balancer instrument taking measurements pre- and post-releases. Patients were assessed by an independent observer using the Oxford Knee Score, the American Knee Society Score and radiographic evaluation, with a minimum follow-up of 12 months.

Results: Extensive soft tissue releasing procedures showed no significant difference in outcome in comparison with minimal releases. For the 2 surgeons using the ‘balancer’ technique, a significant difference was seen with the change in knee scores. The knees left imbalanced had substantially lower change scores and the imbalanced – balanced group showed the most improvement. There was no significant difference between surgical technique or range-of-movement with outcome. Complication rates were low, clinically representative and showed no significant difference between the groups.

Conclusions: Extensive soft tissue releases do not result in an increase in complication rate or a poorer short-term outcome. When comparing traditional and ‘balancer’ guided techniques there is no difference in outcomes. Balancing an imbalanced knee significantly improves knee outcome.