Abstract
Soft tissue balance is known to be an important factor for the success of Total Knee Arthroplasty (TKA). This is of particular relevance in the surgical management of a valgus knee which has both bony and soft tissue abnormalities which need addressing. The correction of instability, particularly in severely valgus knees is essential to post operative outcome as instability is often a component of pre-operative functional disability. Traditional surgical techniques involve soft tissue releases and bony cuts to achieve the correct balance. Evaluation of balance is currently based on subjective intra-operative 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 tissue releases using this instrument may be extensive.
502 patients aged 45–90 years underwent 522 Kine-max TKAs, performed by seven surgeons in five centres between October 1999 and December 2002. Soft tissue releases were recorded and objective soft tissue balance recorded using a balancer device. Independent observers assessed patients using 3 outcome measures for a minimum of 12 months. Pre-operative alignment was divided into 6 groups according to the degree of varus or valgus deformity (mild, moderate, severe varus or valgus).
There is a significant difference in the improvement of the knee scores between the severely valgus knees and all varus knees (ANOVA p=0.000). Significant differences were found between pre-operative pain scores, knee scores and medio-lateral stability between severely varus and severely valgus knees (ANOVA p=0.029, p=0.000 & p=0.000 respectively).
Knees with severe valgus deformities have significantly worse pre operative scores and show greater improvement with equivocal post-operative outcome, when compared to those with severe varus deformity. In addition to pain relief, is the correction of instability the key to this improvement in this group of patients?
Correspondence should be addressed to Dr Roger Bayston, Division of Orthopaedic and Accident Surgery, Queen’s Medical Centre, Nottingham, NG7 2UH, England.
