Abstract
Femoral neck fractures following arthroscopic osteochondroplasty of the femoral head-neck junction for femoroacetabular impingement have been observed in our practice and anecdotally reported in the literature. The aim of the present study was to assess the rate of fracture, identify risk factors, and determine the impact on short-term patient outcome.
Our prospectively recorded database of 431 consecutive hip ar-throscopies was retrospectively analyzed to identify patients who had suffered a postoperative femoral neck fracture. Seven cases were found and comprised the study group (SG). For evaluation of potential risk factors, the SG was compared with all 376 cases that had undergone femoral osteochondroplasty (OG) for age, gender, height, weight and BMI. Additionally, the bony correction in the SG was measured on conventional radiographs as well on either an MRI or CT scan and compared with a reference group (RG). Clinical outcomes were determined from analysis of preoperative and postoperative WOMAC scores and compared between SG and RG.
1.9% (7 males) sustained a fracture after minor trauma that occurred at an average of 4.4 weeks postoperatively. The SG had a significantly higher mean age (p=0.01) when compared with the OG. The postoperative alpha angles were significantly (p=0.006) lower on radial reformations scans in the SG then in the RG. The resection depth ratios measured in the SG were significantly higher on both x-rays (p=0.022) and scans (p=0.013). Using receiver-operating characteristic (ROC) curves cut-off values for age and resection depth ratio on standard x-rays were found to be 44 years and 18%, respectively. After a mean follow-up 20 months there was a significant lower WOMAC (p=0.030) in the SG and no gain pre to postoperatively.
Male gender, older age (>44 years) and depth of bony resection (>18% head radius) were found to be independent risk factors for fracture. Femoral neck fracture has a negative impact on patient's short-term outcome. We are now more conservative with the post operative rehabilitation protocol for at risk patients.
