SUB-VASTUS VERSUS MEDIAL PARAPATELLAR ARTHROTOMY FOR TOTAL KNEE ARTHROPLASTY (SMAK): A RANDOMISED CONTROLLED TRIAL

Abstract

Introduction: Fifty thousand knee replacements are performed annually in the UK at an estimated cost of £150 million. However, there is uncertainty as to the best surgical approach to the knee joint for knee arthroplasty. We undertook a randomised controlled trial to compare a standard medial parapatellar arthrotomy with sub-vastus arthrotomy for patients undergoing primary total knee arthroplasty in terms of short and long term knee function.

Methods: Two-hundred and thirty-one patients undergoing primary total knee arthroplasty during 2001–2003 were recruited into the study. Patients were randomised into subvastus (116) or medial parapatellar (115) approaches to knee arthroplasty. The primary outcome measures were the American Knee Society and WOMAC Scores. The secondary outcome measures were patient based measures of EuroQol and SF-36. All outcomes were measured pre-operatively, 1, 6, 12 and 52 weeks post-operatively. We also looked at a pain diary, analgesia diary, ease of surgical exposure, and complications.

Results: Pain as measured by WOMAC was significantly less in the subvastus group but only at 52 weeks. The Knee Society Score showed some early benefit at one week to the subvastus group. There was no difference between the two groups in relation to the knee function score, EuroQol, SF-36, pain diary, analgesia usage and length of hospital stay

Conclusion: There is some benefit to patients receiving sub-vastus arthrotomy relative to medial para-patellar. Although the results show some statistical significance in using the sub-vastus approach the clinical importance of these findings and the costs of the various procedures involved remain to be ascertained.