THE “MIS EFFECT” IN TOTAL JOINT REPLACEMENT

Abstract

Introduction: Minimally invasive surgery (MIS) in total joint replacement is a heavily if not fiercely discussed issue in orthopaedic surgery. Proponents of such techniques report faster healing and mobilization and strikingly satisfied patients, whilst critics warn of devastating complications. Although a large number of randomised, controlled trials and other studies have been published, the field is still characterized by inconsistent results. This study asked whether there is, in the entirety of the published literature, evidence in favor of or against the use of MIS techniques in total joint replacement.

Methods: We conducted a systematic review of ran-domised, controlled trials in the online databases PubMed, EMBASE, and the Cochrane Controlled Trial Register, as well as by hand-searching relevant publications. Subsequently, we pooled data for the effect of minimally invasive surgery (MIS) separately in individual meta-analyses per joint. 95% confidence intervals (CI) were constructed for the pooled estimates of the endpoints duration of procedure, estimated blood loss, perioperative complication rate, outliers in component placement, postoperative scores, hospital stay, and incision length. For these endpoints, the 95%CIs, which include the true population effect with 95% confidence, were compared for areas of overlap among different joints, which would indicate a common, independent effect of MIS techniques. The distance from zero and the spread of these overlaps are used to infer statistical significance.

Results: Data on 1161 patients in 12 trials were available. We found common effects for all endpoints, with average overlap of 62.4% and 50.5%, respectively. The common effects for component position, blood loss, postoperative scores, and incision length were significantly different from zero. Their absolute values were rather small at 20 mL to 70 mL less blood loss and a difference in effect size of 0.03 to 0.35 on clinical scores. There was no indication of a difference in complication rates.

Discussion: We could show that there is evidence that MIS total joint replacement is an effective alternative to other treatments. There is no evidence of higher complication rates among 1161 operations. Those results that were significantly better in the MIS group, however, had only small absolute values, suggesting MIS as an alternative but not substitute for classical methods. The question remains if these values are clinically significant or could be increased to sufficient numbers even techniques are developed further. For none of the endpoints we could see better result in the standard technique than with MIS.