Background: Total knee replacements are increasingly being carried out for the arthritic knee. This procedure is constantly being improved upon in order to improve outcome. There is currently no consensus of the best surgical approach for primary total knee arthroplasty. This study aims to test the hypothesis that the subvastus approach has significantly better early functional outcomes compared to the medial parapatellar approach.
Study design: Patients with bilateral knee arthritis who met the inclusion criteria were randomised into either the subvastus or medial parapatellar approach over a twelve month period. All patients had the same prosthesis inserted by one surgeon. Primary outcome measures were the Knee Society Score (KSS) at six (6) weeks post-operatively and evaluation of postoperative pain using the Visual Analogue Score (VAS) on the 2nd and 5th postoperative day. Secondary outcomes included blood loss and transfusion requirements.
Results: Twenty-four knees recruited with 11 knees in the subvastus and 13 in the medial parapatellar group. Results showed a significantly lower postoperative pain in the subvastus group versus the medial parapatellar group (2.8 versus 4.62 p < 0.05). Transfusion requirements for subvastus group was half that needed for the medial parapatellar group; this however was not statistically significant. Evaluation of knee score at six weeks did not show any difference in outcome (80.8 versus 84.27 p > 0.05).
Conclusion: Post-operative pain is significantly reduced in the subvastus group, however short term knee function is not affected by surgical approach.