Introduction. The advantages of metal on metal (MOM) hip replacement are decreased wear rate, preservation of bone stock, anatomical restoration and enhanced stability. Large amounts of metal wear particles and metal ions are released which may induce adverse reactions including local soft tissue toxicity, hypersensitivity reactions, bone loss and risk of carcinogenesis. Aseptic loosening can be the result of a peri prosthetic osteolysis generated as a result of a biological response to particulate wear debris. Our aim in this study was to determine whether a steeply inclined acetabular component would give rise to a higher concentration of metal ions. Patients and methods. Between April 2003 and June 2006, 22 patients had MOM hip replacement for osteoarthritis by a single Surgeon. There were 12 male and 10 female patients. The average age at the time of surgery was 56 years (Range: 44–69 years). We divided the 22 patients into 2 groups, one group (A) of 11 patients with the acetabular inclination angle more than 50 degrees and the other group (B) of 11 patients with the angle less than 50 degrees. The inclination of the acetabular cup was measured using a standard AP radiograph of the pelvis. The patients had metal ion levels (blood chromium and serum cobalt) measured at an average follow up of 3.2 years (Range 2.4 to 5 years). Results. Mean blood chromium level in the group A (146 nM/L) was significantly higher (p=0.005) than in Group B (92 nM/L). Mean serum cobalt level in the group A (245 nM/L) was significantly higher (p=0.002) than in Group B (110 nM/L). Discussion. The early to mid term published results of MOM hip replacements have been encouraging. There are, however, a number of concerns about the MOM bearing. Although its wear rate is low, it still releases metal ions into the body particularly cobalt and chromium since most metal on metal bearings are made of a cobalt chromium alloy. The long-term consequences of increased levels of these ions in the body are not known. High concentrations of Co and Cr are toxic and are known to interfere with a number of biological functions. There also have been recent reports of soft tissue reactions with MOM hip replacement. In the light of these concerns, it is important to examine factors which may influence the release of metal ions after MOM hip replacement. It has been reported in the recent literature that the position of the acetabular component will influence the bearing wear inturn leading to the release of metal ions after MOM hip replacement. Our findings indicate that steeply inclined acetabular components with an inclination angle greater than 50 degrees gives rise to higher concentration of metal ions

INTRODUCTION. The introduction of hard-on-hard bearings and the consequences of increased wear due to edge-loading have renewed interest in the importance of acetabular component orientation for implant survival and functional outcome following hip arthroplasty. Some studies have shown increased dislocation risk when the cup is mal-oriented which has led to the identification of a safe-zone1. The aims of this prospective, multi-centered study of primary total hip arthroplasty (THA) were to: 1. Identify factors that influence cup orientation and 2. Describe the effect of cup orientation on clinical outcome. METHODS. In a prospective study involving seven UK centers, patients undergoing primary THA between January 1999 and January 2002 were recruited. All patients underwent detailed assessment pre-operatively as well as post-op. Assessment included data on patient demographics, clinical outcome, complications and further surgery/revision. 681 primary THAs had adequate radiographs for inclusion. 590 hips received cemented cups. The primary functional outcome measure of the study was the change between pre-operative and at latest follow up OHS (OHS). Secondary outcome measures included dislocation rate and revision surgery. EBRA was used to determine acetabular inclination and version. The influence of patient's gender, BMI, surgeon's grade and approach on cup orientation was examined. Four different zones tested as possibly ± (Lewinnek Zone, Callanan's described zone and zones ± 5 and ±10 about the study's mean inclination and anteversion) for a reduced dislocation risk and an optimal functional outcome. RESULTS. There were 21 dislocations (3.1%) and 8 (1.2%) patients required revision at a mean follow up of 7 years. Experienced surgeons (2=0.047) and those operating with the patient in the lateral decubitus position (p=0.04) were more likely to achieve a cup orientation within any of the tested zones. Surgical approach (2=0.14) and patient's BMI (2=0.93) had no influence on whether a cup was within or outside any zone. There was no difference in dislocation rate between the posterior and anterio-lateral approaches (2=0.88). None of the zones tested had a significantly reduced dislocation risk (2=0.13), nor revision risk (2=0.55). OHS was not different for patients with cups within or outside any of the zones tested (p=0.523). DISCUSSION. There was a wide variation in cup orientation. Despite the wide scatter in cup orientation, no safe zone could be identified that would reduce dislocation and revision rate, nor improve patient reported outcome (OHS). Hence, these data suggest that acetabular component orientation should not be considered predictive of patients' early/mid-term complication/revision rate and outcome following THA

Introduction

treatment of femoral neck fractures in the physically active elderly, is still an open question. The comparison of total replacement and partial hip replacement showed substantial superiority of the first approach than the latter. We can not disregard the problems that THR can lead in the elderly: more surgical time, greater blood loss, major sacrifice of bone in osteoporotic subjects. The Tribofit® acetabular system, has the objective to overcome these problems with the implantation of a single 3mm soft, pliable buffer made of polycarbonate-urethane between the large diameter metal femoral head and the subchondral bone, thus replacing the articular cartilage. The surgical technique includes the reaming of the cartilage layer, the creation of a circumferential groove and the snap-fit insertion of the buffer.

The purpose of the prospective study was to evaluate the effectiveness of this approach in the treatment of femoral neck fractures in the elderly.

Introduction. Dislocation following total hip arthroplasty THA is a major short term complication not infrequently resulting in revision arthroplasty. Malposition of the acetabular component in THA results in a higher rate of dislocation as well as increased wear and osteolysis. The aim of this study was to assess the effect of mode of fixation on positioning of the acetabular component. Patients, materials and methods. For all THAs performed at our hospital in 2008, angle of acetabular inclination was measured using PACS by two independent observers. Interobserver and intraobserver reliability were assessed (Pearson's correlation coefficient, r). We determined whether the number of acetabular components outside the target angle range (eg:45±5°) was significantly different between cemented and cementless THA (chi squared test). An enquiry was made to the National Joint Registry (NJR) in respect to incidence of revision for dislocation of THA using cemented and cementless acetabular components, 2004–2009. Results. During 2008 126 THA were performed, 80 cemented and 46 cementless. There was good reliability of angle measurement (interobserver: r=0.89; intraobserver: r=0.87 and 0.97). More cemented acetabular components were within target angle range compared to cementless (cemented 32/80, cementless 29/46; chi squared=6.39, p<0.05). Using data from NJR comparing the number of primary hip replacement operations with number of revisions due to dislocation found a higher rate for cementless THA, 0.381% (266/69,822) than for cemented, 0.282% (262/92,928) (Odds ratio: 1.35 (95% CI 1.14–1.60; P<0.05). Conclusion. Positioning of the acetabular component is more difficult when using cementless systems as implant position is determined by orientation of reaming whereas with cement there is potential for fine implant position adjustment on insertion. The choice of a cementless acetabular component significantly increases the incidence of dislocation post THA. Acetabular component malposition is likely to be a factor in this increased incidence

Background. An increasing number of hip prostheses are inserted without bone cement. Experimental research has shown that hydroxyapatite (HA) coated implants are strongly fixated in the bone, which is believed to reduce the likelihood of prosthetic loosening. However, in recent years, there has been much debate about the role of HA particles in third-body polyethylene (PE) wear and formerly we have shown the revision rate to be high among older-design HA coated cups. Purpose. We hypothesized increased PE wear-rate using HA coated acetabular components in comparison with non-HA coated components (control group). Materials and Methods. We performed a retrospective comparative clinical study based on two patient populations identified in the Danish Hip Arthroplasty Registry (October 2006). All patients had primary total hip arthroplasty (THA) between 1997 and 2001 with cementless Mallory-Head acetabular components. One group received HA coated acetabular components (75 patients, 77 hips). The other group received identical components without HA (70 patients, 73 hips). In all cases the liner was similar and 28 mm metal femoral heads were used. All patients were invited for a radiographic follow-up in 2007. The AP radiographs were analysed for two-dimensional (2D) polyethylene wear using the semi-automated PolyWare software. All cases of non-responders, stem revisions, hip dislocations and patients with less than 5 years of follow-up were excluded from the analysis. Findings/Results. The 2D linear PE wear-rate of 0.18 mm/year (SD 0.09) was higher (P<0.001) in the group with HA coated cups (n = 54) compared with 0.12 mm/year (SD 0.07) in the group of non-HA coated cups (n = 35). The Effect size of the difference in linear PE wear-rate, established as Cohen's d, was large (0.9). The time of follow-up was similar (p = 0.11) in the HA group (7.2 years) versus the non-HA group (7.6 years). There was no case-mix concerning distribution of gender and operated side in the groups; however, the mean age was lower (P = 0.001) in the HA group (57 years) compared with the non-HA group (63 years). Conclusions. We found a significantly increased PE wear rate in HA coated acetabular components at midterm follow-up. The patients with HA coated cups were younger on average, and this might partly explain the findings because the activity level expectedly is higher in younger patients. Still an effect size of 0.9 is large and should raise concern and supplement considerations in future clinical decisions on component selection. A randomized (RSA) study on newer type crosslinked polyethylene liners is recommended to bring about more information on the clinical performance and longevity of HA coated acetabular components

Aims

For displaced femoral neck fractures (FNFs) in geriatric patients, there remains uncertainty regarding the effect of total hip arthroplasty (THA) compared with hemiarthroplasty (HA) in the guidelines. We aimed to compare 90-day surgical readmission, in-hospital complications, and charges between THA and HA in these patients.

Between July 2000 and December 2002, 263 consecutive patients across 5 surgical centers underwent to a revision surgery of a failed acetabular component in which TM acetabular components were used. There were 150 women and 113 men with a mean age of 69.5 years. The indication for acetabular revision was aseptic loosening in 186 cases (70.7%). Clinical evaluations were performed using the Harris hip score, the WOMAC and UCLA activity scale. Implant and screw position, polyethylene wear, radiolucent lines, gaps, and osteolysis were assessed. Preoperatively, acetabular bone deficiency was categorized using the classification of Paprosky et al. Statistical analysis was performed using nonparametric correlations. Standard life table was constructed, and the survival rate was calculated by means of Kaplan-Meier method. The overall mean follow-up was 73.6 months (range, 60–84 months), and no patient was lost to follow-up. The preoperative HHS rating improved from a mean of 43.6 ± 11.4 before revision, to a mean of 82.1 ± 10.7. None of the patients was re-revised for loosening. The cumulative prosthesis survival was 99.2% at 5 years. There was no correlation found between the various degrees of acetabular bony defect and the magnitude of clinical results (independent of pre-revision Paprosky grade). The use of component augments allowed us to minimize the volume of morsellized allograft used for defect repair. TM acetabular component demonstrates promising midterm results similar to those reported by other authors

Introduction. Although femoral neck fractures remain a concern in short term failures for hip resurfacing, acetabular component position and fixation are increasingly being recognized as causes of mid term failures for hip resurfacing. This study aimed to evaluate the migration pattern of a cobalt chrome, beaded acetabular component for a metal on metal hip resurfacing. Methods. 130 patients underwent metal on metal hip resurfacing: 66 hips in 60 patients had sufficient films to be included in this analysis. Forty-eight patients were male and 12 were female, with a mean age of 50 (range, 32–66). Ninety-five percent of the procedures were performed for osteoarthritis. In all cases acetabular migration was measured both vertically and horizontally, on serial radiographs using the computer-assisted Ein Bild Röntgen Analyse method. A minimum of three comparable radiographs is necessary for calculating the migration curves. We scored medial migration as negative horizontal movement. Results. At a mean follow up 25.3 months (24–36 months), each hip had an average of 5.1 radiographs for analysis. 12.5% of the cups showed more than 1 mm migration in the medial-lateral axis and 45.3% more than 1 mm in the vertical axis. 23% of the cups showed a combined migration of greater than 2 mm in the observation period. Two of these cases required revision for aseptic loosening at 34 months. Discussion and Conclusion. Previous studies have shown EBRA to have an excellent sensitivity and positive predictive value for mid to long term cup failure. This data raises concern about the initial stability if this acetabular component. Continued follow-up is needed to monitor the longer term survival of this implant

We present our results of cementless total hip arthroplasty with a tapered, rectangular stem made of titanium-aluminum-niobium alloy. This implant is used since 1979 with only minor modifications. The design of the femoral component achieves primary stability through precision rasping and press-fit implantation. Between October 1986 and November 1987, two hundred consecutive patients (208 hips) underwent total hip arthroplasty with this tapered, rectangular stem. In all cases the acetabular component was a threaded cup made of titanium. At a minimum follow-up of twenty years eighty-seven patients were still alive. Sixty-seven patients (69 hips) were available for clinical and radiographic follow-up. The probability of survival of the stem was 0.96 (95% confidence interval, 0.91 to 0.98) and that of the cup was 0.72 (0.62 to 0.80). The probability of survival of both the stem and the acetabular component with revision for any reason as the end point was 0.71 (0.61 to 0.78). Two stems have been revised due to aseptic loosening. We found various degrees of osteolysis around the acetabular and femoral component (61,7%). At the time of the 20-year follow-up no stem was deemed at risk for loosening. The key findings of our twenty-year follow-up are the very low rate of revisions of the femoral component and the low rate of distal femoral osteolysis associated with this stem. Our data show that femoral fixation of the stem continues to be secure at a follow-up of twenty years

Fractures of the proximal femur are one of the greatest challenges facing the medical community, constituting a heavy socioeconomic burden worldwide. Controversy exists regarding the optimal treatment for independent patients with displaced intracapsular fractures of the proximal femur. The recognised alternatives are hemiarthroplasty and total hip replacement. At present there is no established standard of care, with both types of arthroplasty being used in many centres. The principal advantages of total hip replacement are a functional benefit over hemiarthroplasty and a reduced risk of revision surgery. The principal criticism is the increased risk of dislocation. We believe that an alternative acetabular component may reduce the risk of dislocation but still provide the functional benefit of total hip replacement in these patients. We therefore propose to investigate the dislocation risk of a dual-mobility acetabular component compared with standard polyethylene component in total hip replacement for independent patients with displaced intracapsular fractures of the proximal femur within the framework of the larger WHiTE (Warwick Hip Trauma Evaluation) Comprehensive Cohort Study. Cite this article: Bone Joint Res 2013;2:210–13

Introduction. Acetabular bone deficiency presents one of the most challenging problems during revision hip arthroplasty. A variety of surgical options and techniques are available including impaction bone grafting. We present our medium to long-term experience of 68 consecutive hips in 64 patients who had acetabular revision using impacted cancellous bone grafting with bone cement with a mean follow up of 10.5 ±3.75) years (range 5.1 to 17.7 years). Methods. Patients' undergoing acetabular bone grafting during revision hip arthroplasty prior to insertion of a cemented cup between 1993 and 2000 were evaluated. Pre-operative, immediate post-operative, 1 year post-op and final follow-up radiographs were evaluated. The pre-operative bone loss was graded according to the AAOS and Paprosky classifications. The presence of radiolucencies, alignment and incorporation of bone graft were evaluated. The Harris Hip Score (HHS) was used to assess clinical outcome. 13 patients who were unable to attend the department were contacted for a telephone interview. Analysis of the Data was carried out using SPSS17 [SPSS Inc. Chicago, Illinois]. Results. 64 consecutive patients (68 hips) were evaluated with an average age of 69.9 (± 10.24) years. At the mean follow up of 10.5 years [5.1–17.7 years] Kaplan-Meier survivorship analysis predicted a rate of survival of the acetabular component of 95.5% (95% confidence interval (CI) 92 to 99) at 10 years, with revision for any reason as the endpoint. The median Harris hip score at final follow up was 79.5 [IQR 67.9–80.45]. Neither the extent of initial defect or acetabular inclination were related to clinical outcome or predicted further revision. Progression of the radiololucent zones between the cement bone interface was a predictor of loosening and further revision. Discussion. Our findings have shown that acetabular revision using impacted cancellous bone graft and a cemented acetabular component remains a reliable and successful technique for patients with poor femoral bone stock

Introduction. The MITCH PCR is an anatomic, flexible, horse-shoe shaped acetabular component, with 2 polar fins. The rationale of the PCR cup design is to reproduce a near-physiological stress distribution in the bone adjacent to the prosthesis. The thin composite cup is designed to fuse and flex in harmony with the surrounding bony structure. Only the pathological acetabular cartilage and underlying subchondral bone of the horseshoe-shaped, load-bearing portion of the acetabular socket is replaced, thus preserving viable bone stock. The PCR is manufactured from injection moulded carbon fibre reinforced polyetheretherketone (PEEK), with a two layer outer surface comprising hydroxyapatite and plasma sprayed commercially pure titanium. It is implanted in conjunction with a large diameter low wear femoral head, producing a bearing that will generate minimal wear debris with relatively inert particles. Pre-clinical mechanical testing, finite element analysis and biocompatibility studies have been undertaken. FEA evaluation predicts preservation of host bone density in the load bearing segments. A pilot clinical study was completed on a proto-type version of the PCR cup (the “Cambridge” cup), achieving excellent 5 and 10 year results. Subjects and Methods. We report the three-year results from a two-centre, prospective clinical evaluation study of the MITCH PCR cup. Patient outcome has been assessed using standardised clinical and radiological examinations and validated questionnaires. The change in physical level of activity and quality of life has been assessed using the Oxford Hip Score, Harris Hip score and the EuroQol-5D score, at scheduled time-points. Serial radiographs have been analysed to monitor the fixation and stability of the components. Results and Conclusions. In total 25 PCR cups were implanted by 3 surgeons. There were 12 men and 13 women. The mean patient age at time of surgery was 67 years (range 57–74). An Accolade TMZF stem was used as the femoral component in 19 patients and an Exeter stem in 6. The mean Oxford Hip score improved from 19.8 pre-operatively to 45 at the latest follow-up. The mean Euroqol-5D score improved from 62.6 to 83.6 and the Harris Hip score improved from 49.9 to 90.6. Three adverse events were noted in 2 patients (2 chest infections and 1 deep vein thrombosis). One revision of the acetabular component was performed at 21 months for squeaking. This has been investigated and modification of the articular geometry has resolved the problem on in-vitro testing

Introduction. Acetabular cup positioning has been linked to dislocation and increased bearing surface wear. A previous study found correlations between patient and surgical factors and acetabular component position. The purpose of this study was to determine if acetabular cup positioning improves when surgeons receive feedback on their performance. Methods. Post-op anteroposterior (AP) pelvis and cross-table lateral radiographs were previously obtained for 2061 patients who received a total hip arthroplasty (THA) or hip resurfacing from 2004–2008. The surgeries were performed by 7 surgeons. AP radiographs were measured using Hip Analysis Suite to calculate the cup inclination and version angles. Acceptable ranges were defined for abduction (30–45 °) and version (5–25 °). The same surgeons performed a THA or hip resurfacing on 385 patients from January 2009 through June 2010. Cup inclination and version angles for this set of surgeries were compared to surgeries from 2004–2008 to determine if cup inclination and version angles improved in response to previous acetabular cup positioning studies. Improvement in accuracy was assessed by the chi-square test. Results. Time 1, from 2004 through 2008, had 1952 qualifying hips with 1845 having both version and abduction, and Time 2, from 2009 through June 2010, had 385 qualifying hips, all of which had both version and abduction angles. For Time 1, 1192 (62%) acetabular cups were within the abduction range, 1422 (79%) were within the version range, and 908 (49%) were within the range for both. For Time 2, 276 (72%) acetabular cups were within the abduction range, 250 (65%) were within the version range, and 217 (56%) were within the ranges for both. Accuracy of abduction angle improved (p<0.01) while accuracy of version angle decreased (p<0.01). Accuracy of acetabular cup positioning being within range for both abduction angle and version angle improved significantly (p=0.01), by 7%. Conclusions. Increased awareness and feedback on the resulting abduction and version measurements from THA surgery over time improves the positioning of the acetabular component. A system where objective measurements are presented to the surgeon can significantly improve cup placement which could improve the clinical outcome of THR patients

INTRODUCTION. Although simulation studies have shown superior wear properties of metal-on-metal articulations, increased concern exists regarding the excess in-vivo wear of a small number of Metal-on-Metal-Hip-Resurfacing (MoMHRA) implants. Serum ion levels of Chromium (Cr) and Cobalt (Co) are surrogate markers of wear. Risk factors associated with increased wear include female gender, small components, dysplasia, cup orientation outside safe zone and femoral head downsize during surgery with an associated decrease in Head-Neck-Ratio (HNR). However, these factors are interlinked. This study aims to identify the factors that are most important for subsequent wear of MoMHRA, by performing a multivariate analysis. METHODS. 206 patients (124M: 82F) with unilateral MoMHRA were included in this study. The average follow up was 3.3 years. All patients had Cr/Co levels measured at follow up. Inclination and anteversion of each cup were measured using EBRA. Cups were analysed as being within or outside the previously defined optimum-zone. HNR measurements were made from pre-operative (HNRpre) and post-operative (HNRpost) radiographs. The immediate changes in HNR (downsize/upsize of femoral head) as a result of the operation were expressed as:. HNRprepost=HNRpost–HNRpre. Multivariate linear regression modelling was used to explore the association between measures of ions with the following predictor variables (gender, age, diagnosis, femoral component size, orientation of the acetabular component, head/neck ratio and position of femoral stem). Analyses were carried out separately for each outcome (Cr and Co). Classification and Regression Tree (CART) models were fitted as a complimentary approach to regression modelling. RESULTS. Articular surface downsize followed by cup orientation within/outside optimum zone, followed by cup anteversion followed by gender were the strongest predictors of ion levels. A percentage decrease in HNRartpost, predicted an increase in Cr ion level by 5% (and 6% for Co). If the cup was within the optimum zone this was associated with decreased levels of Cr and Co ions. As acetabular component anteversion increased, levels of ions increased. Gender had a strong effect on ion levels. Adjusting for other variables, the effect of gender was attenuated due to a confounding effect of component size and the amount of femoral head downsize. Predictors identified as important in regression analyses were similar to those produced in the CART model, where the highest levels of ions were seen in patients with a percentage decrease in pre-operative HNR −11.3. DISCUSSION. This analysis shows that (surgical) factors, such as amount of femoral head downsize at operation and whether the cup was orientated within the optimum zone, explained the majority of the variability in ion levels in MoMHRA

Hip resurfacing has grown rapidly since its introduction in the United States, as an alternative to total hip replacement in the younger, active patient. Some studies have suggested a steep learning curve and a higher complication rate when compared to THR. Existing studies have originated from the pioneering surgeons, using a specific type of resurfacing implant. The purpose of this study was to look at the experience of a single, non-inventor surgeon with the adoption of hip resurfacing, using 3 different implants. M&M. All consecutive hip resurfacings performed by the senior surgeon between 2004 and 2008 were included, providing a minimum 2 year followup period. 3 different implant types were used; 2 of these were used as part of the clinical trials, and 1 was used after US FDA approval. A total of 560 hip resurfacings were eligible for the study based upon a minimum of 2 year followup. Results. Nine revisions were performed in this cohort (1.6%). 2 were femoral conversions to endoprostheses for femoral neck fracture; 3 additional femoral conversions were done for osteonecrosis of the femoral head. 1 acetabular revision only was performed for malposition. 2 revisions to THR of both the acetabular and femoral components were done for acetabular loosening and excessive metal production (edge loading). There was 1 revision for metal hypersensitivity. Overall, the K-M survival curve is 98.1% at 4 years. There was no difference with regard to survival from additional surgery with regard to the different implant types. Radiographic signs of failure were also documented. In this cohort, 3 femoral and 1 acetabular components were identified to be radiographically loose, giving a K-M survival from clinical and radiographic failure to be 96.8% at 4 years. Discussion. Hip resurfacing can be adopted successfully with a low rate of reoperation, by the use of careful patient selection. A single surgeon's experience with 3 different types of implants demonstrated no difference in clinical results between the devices

Introduction. The anterior mini-invasive approach to performing total hip arthroplasty (THA) is associated with less soft tissue damage and a shorter postoperative recovery than other methods. In August 2008, our hospital abandoned the traditional lateral Hardinge approach in favor of this new method. The purpose of this study was to measure changes in short-term clinical and radiological results and complications after the changeover. Methods. We compared the first 100 patients operated after the changeover to the new method (MI group) to the last 100 patients operated using the traditional method (LH group). Clinical and radiological parameters and complications were recorded pre- and postoperatively and the collected data of the two groups were statistically analyzed and compared. Results. There were no statistically significant differences between either group with regard to patient demographics or procedural data, placement of the femur component, postoperative leg discrepancy, prosthesis dislocation, blood transfusion, or postoperative dislocation of the components. The MI group had a significantly shorter hospital stay (p<0.001) and significantly fewer infections (p = 0.007) of the operative site. The LH group had a significantly shorter operative time (p<0.001), less bleeding (p = 0.035), less nerve damage (p = 0.013), and radiologically better positioning of the acetabular component regarding anteversion (p<0.001). Furthermore, a few other recorded surgical complications were more frequent in the MI group, but the difference was not statistically significant. Interpretation. Our results show that the anterior approach correlates with faster postoperative recovery and less soft tissue damage with respect to the lateral approach. Since the changeover, we observed an increase in the overall complications, but in this study this increase was not found to be statistically significant. These complications were not only found in the initial patients operated with the mini-invasive approach, but were homogeneously spread over all 100 patients. Additionally, and perhaps most worrying was the clinically significant increase in intraoperative femur fractures in the MI group. The changeover to the anterior mini-invasive approach, which was the surgeons' initial experience with the MI technique, resulted in a drastic increase in the number of overall complications. A future randomized, prospective study including functional scores and a large body of patients will be imperative to show whether the two different approaches really are equivalent

Introduction. Malalignment of some designs of stem is associated with an increased risk of aseptic loosening and revision. We investigated whether the alignment of the cemented polished, double-taper design adversely affected outcome, in a multicentre prospective study. Methods. A multicentre prospective study of 1189 total hip replacements was undertaken to investigate whether there is an association between surgical outcome and femoral stem alignment. All patients underwent a primary THR with the Exeter femoral stem (Stryker Howmedica Osteonics, Mahwah, NJ) and a variety of acetabular components. The primary outcome measure was the Oxford hip score (OHS) and change in OHS at five years. Secondary outcomes included rate of dislocation and revision. Radiographic evaluation of the femoral component was also undertaken. The long axis of the Exeter femoral component and the long axis of the femoral canal were located, and the angle at the point of intersection measured. The cementing quality was determined as defined by Barrack et al. Radiolucent lines at the cement-stem and cement-bone interface in the five year radiographs were defined using the zones described by Gruen et al. Subsidence was measured as the vertical dimension of the radiolucency craniolateral to the shoulder of the stem in Gruen zone 1 as described by Fowler et al. Cement fractures were recorded. Results. The incidence of varus (>5 ° to the femoral axis), and valgus (>5 °) malignment were 3.7% and 0.8% respectively. Pre-operative demographics and OHS were similar in all groups (p > 0.4). There was no significant difference in OHS or change in OHS between neutral and malaligned groups at 5 years (neutral, mean=40.1, change=23.1; varus, mean=40.1, change=23.7; valgus, mean=42.0, change=26.6; p=0.46 and p=0.45 respectively). There was no significant difference in dislocation rate between the groups (p=0.66). There was also no significant difference in revision rate (p=0.34). There were no statistically significant differences in the incidence of femoral radiolucency, stem subsidence or cement fracture (p > 0.1). Conclusion. This study provides evidence that both varus and valgus implantation does not compromise the short to medium term clinical results of the cemented, polished, double-taper stems. Longer follow-up is required to establish the influence of stem alignment on the incidence of aseptic loosening and revision

INTRODUCTION. Studies have suggested that there is a reduction in head-neck-ratio (HNR) associated with MoMHRA. A reduction in HNR at operation would decrease range of movement and increase impingement risk. Impingement could lead to 20 edge loading, increasing wear. Serum ion levels of Chromium (Cr) and Cobalt (Co) are surrogate markers of wear. Although acetabular component orientation has been shown to contribute to wear and PT development, the role of a decrease in HNR has only been highlighted in PT development. This study aimed to measure changes in HNR that occur at resurfacing and determine any gender- and component size-specific differences. In addition it aimed to determine whether changes in HNR could be associated with increased wear. METHODS. 84 patients (56M: 28F) with unilateral MoMHRA were included. The mean age at surgery was 57 years. The mean femoral component was 49mm. Components were considered small if <45mm, average if between 45–50mm and large if >50mm. Three designs were implanted; BHR, C+ and Recap. The average follow up was 4 years. All patients had Cr/Co levels measured at follow up. Patients were considered to have high ions if Cr and Co levels were 5.1ppb and 4.4ppb respectively. Pre-operative HNR (HNRpre) and the post-operative HNR (HNRpost) were made from the respective pelvic radiographs. Assuming a 2mm thick cartilage layer, the HNR based on the diameter of the articular cartilage pre-operatively (HNRart) was calculated. The immediate changes in HNR as a result of the operation were expressed relative to articular HNR pre-op:. HNRartpost=HNRpost–HNRart. RESULTS. The changes in HNR at operation were significantly negatively correlated with HNRpre, (p<0.001), (rho=−0.77). Females had greater ion levels (p=0.013) and smaller components (p<0.001). Females had bigger pre-operative HNRart and were downsized more (p<0.001). Similarly, patients with small components had higher ions (p=0.032). They had greater HNRart and were downsized more (p<0.001) Twelve patients comprised the high ion group. These patients had smaller components (p=0.004), greater HNRart and were down-sized significantly more at resurfacing (p<0.001). DISCUSSION. This study highlights HNR changes that occur in resurfaced hips. Females, patients with small components and patients in the high ion group had higher pre-operative HNR and were downsized more at operation. Femoral downsize, would probably increase impingement risk, lead to secondary edge loading and contribute to greater incidence of wear related problems

Aims

Complex displaced osteoporotic acetabular fractures in the elderly are associated with high levels of morbidity and mortality. Surgical options include either open reduction and internal fixation alone, or combined with total hip arthroplasty (THA). There remains a cohort of severely comorbid patients who are deemed unfit for extensive surgical reconstruction and are treated conservatively. We describe the results of a coned hemipelvis reconstruction and THA inserted via a posterior approach to the hip as the primary treatment for this severely high-risk cohort.

Introduction. Large diameter metal on metal cups have been used in total hip arthroplasty advocating superior results with respect to dislocation rates, range of motion and long term survival. The Durom cup used as part of the Durom hip resurfacing system has been incriminated with poor short term results sometimes correlated to incorrect positioning of either the femoral or acetabular component. Our objective was to evaluate short term results of the Durom cup used in conjunction with standard stems. Methods. We prospectively followed all patients with a large diameter metal-on-metal articulation (Durom) and a standard stem operated upon between 9/2004 and 9/2008. Patients were seen at follow-up for a clinical (Harris hip score=HHS, UCLA scale and patient satisfaction), radiographic and questionnaire assessment. Results. 89 primary THAs in 80 patients (74% men) with a mean age of 52 (±12) years were included. Main diagnoses were primary osteoarthritis in 47% and aseptic necrosis in 35%. An uncemented stem was used in 79%. Overall, 80 THAs were controlled at a mean follow-up of 39 months (range 16–67 months), 4 patients were lost to follow-up and 5 patients refused or were unable to attend the visit. However, none of the 5 underwent revision. Overall, 8 THAs (8/85, 9.4%) were revised in mean 28 months (range 8–60) after the operation. One additional patient was awaiting revision for aseptic loosening of both cup and stem. The reasons for revision were aseptic loosening in three cases, presence of a granuloma (histological diagnosis of ALVAL) in three, deep infection in one and impingement in one case. Radiographic analysis revealed linear (n=2) and focal (n=3) osteolysis as well as early cup migration (n=2). In 5 revised patients no radiographic changes were found. 56 (70%) of the 80 patients with follow-up had a HHS between 80 and 100. Among those who were not revised, the mean HHS improved from 55.2 to 88.4 (mean increase 33.2, 95% CI 27.7; 38.7). The mean activity level (UCLA scale) at follow-up was 6.4 (±1.8). Overall, mild to severe pain was reported in 14 cases and occasional pain in 22. Groin pain was present in 18 patients (22.5%), 7 of them belonged to the revised group. 61 (76.3%) of the 80 patients with follow-up were satisfied. Mean patient satisfaction on the VAS scale among those who were not revised was 9.0 (±1.3). Conclusion. This study confirms the increased short-term revision rate of the large diameter metal-on-metal couple (Durom) reported by others. In all revision cases the retrieved cups showed no osteo-integration and were removed easily. The operative indication for revision was based upon groin pain and patient dissatisfaction. Radiographic signs of implant loosening were not always present even though in all revised cases except for one the cup was found loose