The wear performances of polyethylene in THA are influenced at a great extent by the manufacturing process. During the past decade, highly cross-linked materials have been developed with encouraging results in terms of wear, whereas another body of the literature has indicated potential catastrophic failures related to reduced fatigue properties and oxidation due to lipids adsorption and fatigue mechanism. Also, each of the materials available on the market has its own processing characteristics. Therefore, a specific evaluation is necessary for each of them. The aim of this retrospective study was to evaluate the wear properties of metal-back sockets using a first generation highly cross-linked PE in a consecutive series of primary THAs. Between August 2005 and December 2007, 80 patients (80 hips) with a mean age of 62.7 ± 8.9 years were included. All patients had a 28mm CoCr femoral head articulating with a highly cross-linked insert (Highcross®, Medacta SA) that was 100 Mrads gamma radiated, remelted at 150°C, and ethylene oxide sterilized. The primary criterion for evaluation was linear head penetration measurement using the Martell system, performed by an investigator trained to this technique. Also, steady state wear was calculated. Functional results were evaluated according to WOMAC score.Introduction
Materials
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.
The risk that hip preserving surgery may negatively influence the performance and outcome of subsequent total hip replacement (THR) remains a concern. The aim of this study was to identify any negative impact of previous hip arthroscopy on THR. Out of 1271 consecutive patients who underwent primary THR between 2005 and 2009, eighteen had previously undergone ipsilateral hip arthroscopy. This study group (STG) was compared with two control groups (CG: same approach, identical implants; MCG: paired group matched for age, BMI and Charnley categories). Operative time, blood loss, evidence of heterotopic bone and implant loosening at follow-up were compared between the SG and the MCG. Follow-up WOMAC were compared between the three groups. Blood loss was not found to be significantly different between the SG and MCG. The operative time was significantly less (p>0.001) in the SG. There was no significant difference in follow-up WOMAC between the groups. No implant related complications were noted on follow-up radiographs. Two minor complications were documented for the SG and three for the MCG. We have found no evidence that previous hip arthroscopy negatively influences the performance or short-term outcome of THR.
