Introduction

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.

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.

A significant portion of prosthetic joint infections with biofilm-embedded bacteria may not be adequately sampled by standard periprosthetic tissue collection techniques. The aim of the present study was to combine ultrasonication sampling procedures with standard in-traoperative sampling and cultural techniques.

A total of 69 patients with implants to be removed were included in this study; a prosthetic joint infection was diagnosed or rejected according to a standardized clinical score. Intra-operative tissue specimens were cultured using standard techniques; implants were subjected to ultrasonication and sonicates used for inoculation of cultures and broad-range eubacterial PCR.

According to the clinical score, a prosthetic joint infection was present in 14 of the 69 patients. 11/14 had positive cultures for tissue samples, 13/14 had positive cultures when considering in addition the results from sonicate cultures. Sonicate PCR was positive in 12/13, and negative in 1/13 (excluding one infection due to Candida albicans). Ultrasonication improved sensitivity of culture from 78.6% to 92.9%; sensitivity and specificity of PCR from sonicates was 92,3% and 100%, respectively.

Combined with serially sampled periprosthetic tissue, ultrasonication of implants may help to increase the sensitivity of laboratory investigations based on cultural procedures. PCR analyses did not improve sensitivity although implementation of PCR may aid in improving the specificity of cultural detection.

The fear of high complication rates, repeated surgery and component mal positioning, especially early in the surgeon’s experience, can be an obstacle for starting a new technique like minimally invasive THR.

The aim of the present investigation was to report on our learning curve of the first 100 consecutive minimally invasive total hip replacements through an anterior approach and to focus on intraoperative and postoperative complications as well as on the quality of implant positioning.

In order to have a comparison, the last 100 THR performed through our previously used direct lateral approach were retrospectively evaluated. In both groups, complex acetabular and femoral reconstructions were excluded as they were performed though a digastric trochanteric osteotomy. Every change of the initial surgical plan was considered an intraoperative, every change in the rehabilitation plan considered a postoperative complication. The quality of implant positioning was evaluated in a standardized anteroposterior pelvic x-ray and a cross table lateral view at the 3 month follow-up visit and included the positioning of the cup and the stem in both views and the amount of leg-length discrepancy.

In terms of age, gender, BMI, ASA-score and origin of osteoarthritis both groups differed not from each other. Intraoperative and postoperative complications were more frequent in the MIS-Group (17 versus 7) and occurred within the first 30 cases. 12 were solved during the same anesthesia and 2 during the same day without manifest disadvantage at the 3 month follow-up visit. In one case a dislocation occurred. In two patients neuralgia of the lateral cutaneous femoral nerve was successfully treated conservatively. Implant positioning and leg-length discrepancy did not differ between the two groups.

Overall, starting a minimally invasive technique was associated with more frequent complications; however, if recognized and appropriately managed nearly none of them resulted in disadvantages for the patient at the 3 months follow-up visit.

After THR, trochanteric soft tissue abnormalities may be associated with residual trochanteric pain and limping. However, normal MR appearance of the trochanteric region after THR is not known. The aim was to evaluate MR imagings in asymptomatic and symptomatic patients after THR through a transgluteal approach.

Triplanar MR images of 25 asymptomatic (14 men, mean age 60.4 years, 11 women, mean age 60.2) and 49 symptomatic patients (19 men, mean age 62.7 years, 20 women, mean age 64.3) at least 1 year after THR were analyzed by two blinded radiologists. In 14 symptomatic patients MR imaging was correlated to surgical findings.

Tendon defects were uncommon in asymptomatic and significantly more frequent in symptomatic patients (gluteus minimus 8% vs. 56%, p< 0.001; lateral gluteus medius 16% vs 62%, p< 0.001; posterior gluteus medius 0% vs18%, p< 0.025). Signal changes within tendons were very frequent in both groups except for the posterior gluteus medius tendon which demonstrated this finding more frequently in symptomatic patients (20% vs 59%, p=0.002). Changes in tendon diameter were very frequent in both groups but significantly (p=0.001–009) more frequent in symptomatic patients. Fatty atrophy was evident in the anterior two thirds of the gluteus minimus muscle in both asymptomatic and symptomatic patients. In the posterior superior third of the gluteus minimus muscle differences of fatty degeneration were significant. Fatty atrophy of the gluteus medius muscle was only present in symptomatic patients. Bursal fluid collections were more frequent in asymptomatic (32% vs 62%, p=0.021). MR diagnosis was confirmed in all 14 patients undergoing revision surgery.

Although more frequent in symptomatic patients many MR findings are frequently found in asymptomatic patients. However, defects of the abductor tendons and fatty atrophy of the gluteus medius and the posterior part of the gluteus minimus muscle are rare in asymptomatic patients.

Interest on acetabular version arose from unstable developmental dysplastic hips. Initial studies and clinical observations described the dysplastic hip as being excessively anteverted.

The advent of computed tomography allowed further detailed analysis of the acetabulum in the axial plane, yet these studies failed to determine conclusively whether or not the dysplastic acetabulum is abnormally anteverted. Much controversy evolved from different methods of measuring and from the fact that a more anteriorly located acetabular deficiency results in excessive anteversion while a more posteriorly located deficiency in retroversion. It remains inconclusive to what extent acetabular dysplasia is due to a mal-orientation of an otherwise normal configured acetabulum or to a deficient acetabulum which is otherwise normally orientated. Furthermore, the acetabular opening spirals gradually from mild anteversion proximally to increasing anteversion distal to it and therefore render its measurement dependent from pelvic inclination and from the level of the transverse CT scan slice.

On an orthograde pelvic X-ray, both, pelvic inclination and rotation can be controlled. Therefore, acetabular version is best estimated from the relationship of the anterior and posterior acetabular rim to each other on an orthograde pelvic X-ray.

The main hip pathologies, acetabular rim overload and anterior femoro-acetabular impingement, both occur in the superior part of the acetabulum, the acetabular dome, and that’s where version is best measured. We called this version of the acetabular dome.

Interest on retroversion of the acetabular dome arose from analysis of complications such as persistent posterior subluxation after acetabular reorienting procedures. They resulted in the hypothesis that the site of acetabular deficiency may vary and be more posteriorly located in some cases resulting in a rather retroverted than anteverted acetabular dome.

In fact, retroversion of the acetabular dome was found to be a characteristic feature of specific hip disorders. A review of ten patients with posttraumatic premature closure of the triradiate cartilage before age 5 showed beside a bowed hemipelvis with lateralized and caudalized acetabulum a mean retroversion of the acetabular dome of 27°. A review of 14 patients suffering from proximal femoral focal deficiency with a functional hip joint revealed a mean retroversion of the acetabular dome of 24°. Typically this was accompanied by femoral retrotorsion and coxa vara.

Finally, bladder exstrophy, when treated without pelvic osteotomy, typically end up with externally rotated or retroverted acetabula (Sponseller, 1995) Even in DDH, retroversion of the acetabular dome has been shown to be a significant variation as 40 of 232 such acetabula showed to have a retroverted dome (Li, 2003).

Furthermore retroversion typically can result from pelvic osteotomy in childhood as 26 from 97 subjects, who underwent either Salter or Le Coeur osteotomy in childhood ended up with retroverted acetabular domes after closure of the pelvic bone growth plates. In the context of neuromuscular or genetic disorders, dysplastic hips also may have retroverted acetabular domes and may additionally be influenced from fixed spine deformities. Finally, retroverted acetabular domes may be found in otherwise non dysplastic hips.

The relevance of acetabular retroversion is both technical and clinical: First, it calls for a more individual approach to acetabular dysplasia because presence of retroversion will affect the manner in which corrective osteotomy will be done. Salter-like reorientation maneuvers will result in worsening the pre-existing posterior deficiency or acetabular rim overload and risk continued posterior subluxation or dislocation of a previously reduced hip (Lee, 1991). Second, anterior overcorrection of a primarily retroverted acetabula may necessitate a further intervention to remove bone from the anterior aspect of the acetabulum or anterior part of the femoral head-neck junction due to limited hip flexion (Crockarell 1999, Myers 1999). Third, evidence that the long-term effect of retroversion of the acetabular dome is harmful is increasing: An association between decreased acetabular anteversion and osteoarthritis was found as soon as 1991 (Menke, 1991) and the prevalence of retroversion among patients with idiopathic hip osteoarthritis has been found to be 20% versus 5% among the general population (Giori, 2003). Furthermore, decreased acetabular and femoral anteversion was found to be a major cause of altered rotation, hip pain and osteoarthritis (Tönnis, 1999). A positive impingement test was the key clinical finding (Reynolds,1999). This anterior impingement of the femoral head-neck junction against the border of the prominent anterior acetabular wall which over a long period of time may lead to fatiguing and destruction of the acetabular labrum and the adjacent cartilage is thought to initiate groin pain and early osteoarthritis. Finally, even for total hip replacement, severe retroversion of the acetabular dome will make surgery more difficult.