Comparison of minimally invasive surgery and mini-incision technique for total hip arthroplasty: a sub-group meta-analysis

It is well accepted that the minimally invasive surgery (MIS) for total hip arthroplasty (THA) should combine with less or no muscle damage and is different from mini-incision technique and MIS should have better outcomes than mini-incision surgery. The aim of current analysis was to apply an explicitly defined sub-group analysis to confirm whether this hypothesis is true.A computerized literature search was applied to find any data concerning MIS or mini-incision THAs. A multistage screening was then performed to identify randomized studies fulfilling the inclusive criteria for the analysis. The data were extracted, and sub-group analyses of MIS or mini-incision surgery for different kinds of outcomes were carried out. The P(sub) value for difference between MIS sub-group and mini-incision sub-group was also calculated.Eleven studies that fulfilling the inclusion criteria were included, with 472 cases in the study group (MIS or mini-incision) and 492 cases in the conventional group. The overall analysis showed the study group would achieve less surgical duration (P = 0.037), intraoperative blood (P0.001) and incision length (P0.001) than conventional group. The difference between sub-groups showed, the MIS would achieve shorter incision length (P(sub)0.05) and bigger cup abduction angle (P(sub)0.05), and cause more blood loss (P (sub)0.05) than mini-incision technique. Other indexes were comparable between the two sub-groups.Though further high quality studies are still needed, the result of current analysis offered an initial conclusion that MIS THA failed to achieve a better clinical outcome than mini-incision technique. The exact definition of MIS still needs to be improved.