Early Pain Relief and Function After Posterior Minimally Invasive and Conventional Total Hip Arthroplasty A Prospective, Randomized, Blinded Study

Background: Few prospective randomized studies have demonstrated benefits of minimally invasive total hip ar-throplasty when compared with conventional total hip arthroplasty. We hypothesized that patients treated with a posterior mini-incision would have better results than those treated with a posterior long incision with regard to the achievement of established goals for pain relief and functional recovery permitting hospital discharge by the sec-ond postoperative day. Methods: Sixty of 231 eligible patients were randomized (with thirty in each group) to have a total hip arthroplasty performed through either a posterior mini-incision (10 ± 2 cm) or a traditional long incision (20 ± 2 cm). After comple-tion of the total hip arthroplasty, the mini-incision group underwent extension of the skin incision to 20 cm. Patients were evaluated on the basis of self-determined pain scores, requirements for pain medicine, need for assistive gait devices, and time until discharge. Gait analysis provided objective functional assessment. Results: The average hospital stay was 63.2 ± 13.3 hours in the mini-incision group and 73.6 ± 23.5 hours in the long-incision group (p = 0.04). More patients with a mini-incision were discharged by the second postoperative day (p = 0.003) and more were using just a single assistive device at the time of discharge (p = 0.005). As scored on a verbal analog scale of 0 to 10 points, patients with a mini-incision had less pain on each postoperative day and the pain score remained significantly lower at the time of discharge (mean, 2.2 ± 1.0 points compared with 3.1 ± 0.