Comparison of Primary Total Hip Replacements Performed With a Standard Incision or a Mini-Incision

BACKGROUND: Primary total hip replacement performed through an incision that is </=10 cm in length has been advocated as a minimally invasive technique. Proponents have claimed that mini-incision techniques reduce blood loss, transfusion requirements, postoperative pain, and the length of the hospital stay compared with standard techniques through a longer incision. However, we are aware of no well-designed comparison study that supports these claims. The purpose of the present study was to compare the short-term results of a mini-incision with a standard incision technique for total hip replacement. METHODS: A consecutive series of patients who underwent 135 primary unilateral total hip replacements (fifty with use of a mini-incision </=10 cm and eighty-five with use of a standard incision) by three surgeons at one hospital were studied. Each surgeon selected patients to have a mini-incision procedure and performed a standard approach in the remaining patients. A posterior approach was used for all procedures. In-hospital data were collected retrospectively, and the initial postoperative radiographs were analyzed. Because of the selection process, the patients who had a mini-incision had both a significantly lower average body-mass index (p = 0.008) and a lower average score on the American Society of Anesthesiologists rating (p = 0.006), indicating that they were thinner and healthier than the patients who had a standard incision. RESULTS: With the numbers of patients available, no significant differences were found between the groups with respect to the average surgical time, intraoperative blood loss, in-hospital transfusion rate, length of hospital stay, or the patients' disposition after discharge. The mini-incision group was found to have a significantly higher risk of a wound complication (p = 0.02), a higher percentage of acetabular component malposition (p = 0.04), and poor fit and fill of femoral components inserted without cement (p = 0.0036). CONCLUSIONS: There was no evidence that the mini-incision technique resulted in less bleeding or less trauma to the soft tissues of the hip, factors that would have produced a quicker recovery and a shorter hospital stay, than did the standard technique. The present study, which was based on the authors' initial experience with the mini-incision technique, failed to confirm the positive clinical outcomes reported by previous uncontrolled cohort studies, and the findings suggest that further analysis of this new technique is needed before it can be recommended for general use.