Comparison of the minimally invasive and standard medial parapatellar approaches for primary total knee arthroplasty

The minimally invasive surgical (MIS) approach has been popularised as an alternative to the standard medial parapatellar approach (MPP) in total knee arthroplasty (TKA). Advocates of this technique suggest earlier functional recovery due to less injury to the surrounding tissues. Potential disadvantages however may include reduced overall exposure, component malalignment and damage to neurovascular structures. A systematic review and meta-analysis of randomised and quasi-randomised trials were conducted to compare the MIS and MPP approaches in primary TKA. Methodological features were rated independently by two reviewers. Seventeen studies were included involving 733 patients with mean age of 69 (SD +/- A 2.8) in the MIS group and 692 patients with mean age of 68.6 (SD +/- A 3.1) in the MPP group. Using a MIS approach led to significant increase in flexion within the first week after a TKA (mean difference (MD) of 9.9A degrees (95% confidence interval (CI) 8.2-11.6, P < 0.01)). However, this effect was not sustainable at further follow-ups of a parts per thousand yen3 months. MIS showed a significantly increased risk of developing intraoperative complications with a risk ratio (RR) of 7.6 (95% CI 3.5-16.3, P < 0.01). MIS results in superior function in the immediate postoperative period after a primary TKA but is also associated with increased rates of intraoperative complications, and therefore, a standard approach that allows adequate exposure and avoids tension to the wound edges would be more appropriate to prevent such complications. Therapeutic study, Level I.