Computer-assisted Minimally Invasive Total Hip Surgery (MIS): a randomised controlled trial into the effectiveness compared to traditional Total Hip Arthroplasty (THA)
01 / 2007 - 01 / 2011
Objective of the proposed study is to compare the effectiveness of computer-assisted MIS with a traditional incision technique THA. The primary focus will lie on the 6-week and 3-month results. For the 6-month results, analyses will be done with the data available within the two-year period.Primary research questions 1a. Does computer-assisted MIS lead to a better recovery during the early postoperative period (3 months), and at 6 months postoperatively to a recovery at least as good as THA with a traditional incision technique? In this study, recovery is operationalized as the amount of limping during walking as objectified by gait analysis, and as the self-reported functional status and health-related quality of life. 1b. Does computer-assisted MIS result in a decreased length of hospital stay compared to THA with a traditional incision technique? 2. Does computer-assisted MIS lead to the same or even better positioning of the prosthesis compared to THA with a traditional incision technique as measured by means of radiographic evaluation?3. Does computer-assisted MIS lead to a decrease in perioperative complications compared to THA with a standard incision technique?Secondary research questions1. Are there indications that computer-assisted MIS potentially saves costs compared to a traditional incision technique? Samenvatting Moderate to severe osteoarthrosis is the most common indication for Total Hip Arthroplasty (THA). THA has proven to be one of the most successful orthopedic interventions. Minimally Invasive Total Hip Surgery (MIS) and Computer Assisted Surgery (CAS) were introduced several years ago. However, the literature lacks well-designed studies that provide objective evidence of the superiority of computer-assisted MIS compared to a traditional technique. For that reason, the purpose of this study is to compare the effectiveness of computer-assisted MIS with a traditional technique for THA. Primary research question is if computer-assisted MIS leads to a better recovery during the early postoperative period (3 months), and at 6 months postoperatively to a recovery at least as good as THA with a traditional incision technique. Additionally, does it lead to a decrease in length of hospital stay, fewer perioperative complications and a better positioning of the prosthesis, and are there indications for potential cost savings.A cluster randomized controlled trial will be executed. Patients will be stratified by means of the Charnley classification. They will be randomly allocated to have MIS using the minimally invasive single-incision anterior approach or the traditional procedure using a standard posterolateral incision. Measurements take place preoperatively, perioperatively, and 6 weeks and 3 and 6 months postoperatively. In this study the primary focus will be on the 6-week and 3-month results. For the 6-month results, analyses will be done with the data available within the two-year period, after which the follow-up of patients will be completed, making it possible to answer the research questions at 6 months too. Patients with a maximum of 75 years of age admitted for primary cementless unilateral THA will be included. Preoperative and postoperative functional status will be recorded objectively by means of gait analysis. As walking is by far the most important aspect of functional status, we will focus on it, especially on the extent of limping during walking, as this is an evident indication of return to a normal gait. To qualify prosthesis positioning, a radiographic evaluation will take place. Self-reported questionnaires will be used to get an impression of self-reported functional status (WOMAC, SF-36 and EuroQol). At 3 months, the effect of MIS and traditional THA on gait will be compared using chi-square procedures. To be able to detect a difference of 0.254 in the proportion of subjects with normal gait after 3 months of follow-up with 80% power at a significance level of 0.05 in a one-sided test of a difference between two proportions, two groups of 50 subjects are required. At 6 months the effect of MIS and traditional THA on gait (limping) will be compared in a non-inferiority setting. The non-inferiority margin delta is chosen in this study at a value of 0.10, indicating that a difference in proportion of subjects with normal gait of 0.10 is considered clinically equivalent. To deduce non-inferiority with 80% power at a significance level of 0.05 with expected proportions of subjects with normal gait of 0.95 using a non-inferiority margin delta of 0.10, two groups of 60 subjects are required. Descriptive statistics will be used to describe both research groups. Analysis of variance (ANOVA) and chi-square procedures will be used to evaluate between-group differences at baseline. Economic evaluation will focus on differences in costs between computer-assisted MIS and standard THA. The evaluation will be performed from a societal perspective, costs within and outside the healthcare sector will be registered for 6 months. Cost advantages of MIS over THA are expected mainly in the area of hospitalization costs. Additional economic analyses will estimate the cost effectiveness of MIS compared to THA.Time schedule: 1-3months: preparation of the study; 4-18 months: inclusion of patients; 19-21 months: follow-up; 22-24 months: final data analysis, preparation of national/international publications and report.