|Beitragstitel||The incision index: a decision tool for open vs. arthroscopic treatment of femoroacetabular impingement|
Introduction: Surgical hip dislocation (SHD) and hip arthroscopy (HAS) both represent commonly applied approaches for correction of femoroacetabular impingement (FAI) of the hip. Although both procedures proved success, there is an absence of consensus regarding surgical choice. The aim of this study was to define patients likely to benefit from either procedure based on a multivariate analysis.
Patients and method: The cohort included 29 patients (29 hips) undergoing SHD and 53 patients (56 hips) undergoing HAS. Pre- and postoperative radiographic parameters and clinical scores 2 years postoperatively were evaluated, and a multivariate model utilized to determine factors influencing surgical decision. A formula was generated and tested using receiver operated curves (ROC).
Results: The preoperative lateral-centre-edge angle (LCE) and the alpha angle were found to be higher in patients undergoing SHD. More correction of both angles was greater with SHD. Despite greater correction, the alpha angle remained higher in the SHD group. There was no difference between the two groups regarding postoperative LCE and clinical follow up scores 2 years postoperatively. Based on the comparable outcome between groups, we evolved a formula (incision index) defining whether a hip would undergo SHD or HAS in this cohort: In hips with a positive cross over sign: X= alpha angle + (LCE*2). In hips with a negative cross over sign: X= alpha angle + (LCE*1.5). Using 120 as cut off, the Roc-Curve showed a sensitivity of 0.897 and a specificity of 0.786.
In the HAS group, adequate correction of LCE and alpha angle were achieve in 95% of hips with an incision index <120, but only in two thirds of hips with a high index >120, where the LCE was undercorrected. As the average intraoperative correction of LCE was higher in the SHD group, these hips may have benefited from open surgery.
Conclusion: The incision index may act as a tool to aid the decision whether HAS is sufficient as a treatment option or whether more invasive open surgery would be necessary in a patient with symptomatic FAI.