A Comparison of Operative Invasiveness in Minimally Invasive Anterolateral Hip Replacement (MIS-AL) and Standard Hip Procedure, Using Biochemical Markers

Abstract

PURPOSE OF THE STUDY The aim of this prospective randomized study was to compare, by means of biochemical markers, the operative invasiveness of the standard total hip replacement with that of the minimally invasive anterolateral (MIS-AL) approach. MATERIAL Twenty-six randomly assigned patients with standard and 22 patients with MIS-AL total hip replacement were included in the study. Patients with elevated pre-operative levels of the markers evaluated or patients taking medication that might affect marker levels were not included. METHODS Creatine phosphokinase (CPK) and C-reactive protein (CRP) were chosen as markers of muscle damage and post-operative inflammatory changes, respectively. Blood samples were drawn before surgery (less than 24 hours) and after surgery at 24, 48 and 96 hours, which respected biological half-lives of the markers and permitted us to study their dynamics. The results were evaluated and statistically analyzed at the department of biochemistry, using the two sample t-test. RESULTS Statistically significant differences between the two groups of patients were found for both markers. The average CRP values differed significantly (p < 0.05) at 48 and 96 hours post-operatively, being higher for the standard than MIS-AL total hip replacement by 28% and 44%, respectively. The average CPK values showed the most marked difference at 48 hours after surgery, when the level was higher by 62.5% in the standard than MIS-AL total hip replacement (p < 0.05). DISCUSSION Our objective evaluation of the invasiveness of surgery in total hip replacement was based on the most frequently recommended markers for assessment of muscle tissue damage and post-operative inflammatory changes. The study was focused on the invasiveness of surgery only and neither subjective nor objective outcomes of implantation were evaluated. The use of the muscle sparing approach MIS-AL results in minimal damage to muscle tissue and, consequently, a lower degree of post-operative inflammation than is recorded in traditional hip replacement surgery. CONCLUSIONS In the patients undergoing MIS-AL total hip replacement, post-operative levels of CPK and CRP were significantly lower than in the patients with standard total hip replacement. The MIS-AL technique evidently provides a more sparing approach to soft tissues.