The medial parapatellar approach in total knee arthroplasty is arguably the most common approach, but the subvastus approach is less insulting to the quadriceps mechanism.

A single centre, randomized controlled trial was conducted in a metropolitan hospital to investigate whether the subvastus approach afforded better outcomes than the medial parapatellar approach. Ninety participants with knee osteoarthritis were randomized to either the subvastus or medial parapatellar approach. The primary outcome was the American Knee Society Score and secondary outcomes reported included pain, extension and flexion range of motion, quadriceps lag, girth, Oxford Knee Score, 3 meter timed up and go test, days to straight leg raise, surgeon perceived difficulty, operation duration, tourniquet duration and length of stay. Data were collected preoperatively, intra-operatively, days 1,2,3, discharge, 6 weeks and 6, 12 and 18 months post operatively.

Analysis was undertaken on 76 participants revealing no significant difference with the primary outcome (p=0.076; MP 167.3±36.6; SV 153.1±36.6) or any other outcome except for surgeon perceived difficulty, which favored the medial parapatellar approach (p=0.001; MP 3.3/10±1.9; SV 5.4/10±2.3) and days to straight leg raise, which favoured the subvastus approach by 0.9 days (p=0.044; MP 2.8±1.9; SV 1.9±1.6).

The subvastus approach is technically more difficulty and offers no clinical benefit over the medial parapatellar approach.