As there are many reports describing avascular reactions to metal debris (ARMD) after Metal-on-Metal Hip Arthroplasty (MoMHA), the use of MoMHA, especially hip resurfacing, is decreasing worldwide. In cases of ARMD or a rise of metal ion blood levels, revision is commended even in pain free patients with a well integrated implant. The revision of a well integrated implant will cause bone loss. As most of the patients with a hip resurfacing are young and a good bone stock is desirable for further revision surgeries, the purpose of this study was to evaluate the stability of a cemented polyethylene cup in a metal hip resurfacing cup. Two different hip resurfacing systems were investigated in this study (ASR™, DePuy Orthopaedics, Leatherhead, UK; Cormet™, Corin Group, Cirencester, UK). Six different groups were formed according to the treatment and preparation of the cement-cup-interface (table 1). Before instilling cement in groups 1, 3, 5 the surface, which was contaminated with blood, was cleaned just using a gauze bandage. In groups 2, 4, 6 saline, polyhexanid and a gauze were used to clean the surface prior to the cement application. In group one and two the polyethylene cup (PE) was cemented either into Cormet™ or ASR™, just the ASR™ was further investigated in group three to six. A monoaxial load was applied while the cup was fixed with 45 degrees inclination (group 1–4) and 90 degrees inclination (group 5, 6: rotatory stability) and the failure torque was measured. In contrast to group 1 and 2, the cement penetrated the peripheral groove of the ASR™ in groups 3–6. The mean failure torque of five tests for each group was compared between the groups and the implants. The ASR™ showed mean failure torque of 0.1 Nm in group one, of 0.14 Nm in group two, of 56.9 Nm in group three, of 61.5 Nm in group four, of 2.96 Nm in group five and of 3.04 Nm in group six. The mean failure torque of the Cormet™ was 0.14 Nm both in groups one and two (table 2). In groups 1–6 there were no significant differences between the different preparations of the interface. Furthermore, in groups 1 and 2 there were no significant differences between the Cormet™ and the ASR™. The mean failure torque of group 4 was significant increased compared to group 3 (p=0.008). We saw an early failure of the cement fixation due to the smooth surface of the Cormet™ and the ASR™ components in groups 1, 2, 5, 6. In contrast to other hip resurfacing cups the ASR™ has a peripheral groove, which was not cemented except in groups 3 and 4 and therefore the lever-out failure torque was significant increased in these groups. Nevertheless, the groove did not provide stability of the cement-PE compound in case of rotatory movements. In conclusion we do not recommend the use of these methods in clinical routine. The complete removal of hip resurfacing components seems to be the most reasonable procedure

Different types of highly cross-linked polyethylene (HXLPE) have been introduced widely in acetabular cups in hip prostheses to reduce the incidence of wear debris-induced osteolysis. Also, we reported that HXLPE cups with 28-mm alumina ceramic femoral head exhibited lower wear than conventional PE cups. Recently, the combination of HXLPE cup and larger diameter femoral head is used widely to prevent dislocation. In this study, we examined the wear of HXLPE with 32-mm alumina ceramic femoral head and compared it with the wear of HXLPE with 28-mm alumina ceramic femoral head.

The in vivo wear of 60 HXLPE cups (Aeonian; Kyocera Corp., Kyoto, Japan, currently Japan Medical Materials Corp., Osaka, Japan) with 28-mm alumina ceramic femoral head with clinical use for 3.1–9.1 years (mean 7.4 years) and eight HXLPE cups with 32-mm alumina ceramic femoral head used for 2.3–3.2 years (mean 2.8 years) were examined by radiographic analysis.

The early wear rate for the first year of HXLPE cups with 28-mm and 32-mm alumina ceramic femoral head were 0.24±0.10 mm/year and 0.29±0.12 mm/year respectively. There was no significant difference in both femoral head groups (p>0.05). The steady wear rate after 1 year were 0.001±0.03 mm/year and −0.03±0.10 mm/year respectively. There was no significant difference either in both femoral head groups (p>0.05).

These findings from this radiographic analysis suggest that the early wear rate in the first 1 year probably represents the creep deformation in bedding-in stage; and the steady wear rate after 1 year probably represents mainly the wear than of the creep deformation. By the radiographic analysis, HXLPE cups in both femoral head groups exhibited low steady wear rate.

In conclusion, we expect that the combination of HXLPE cup and 32-mm diameter alumina ceramic femoral head has favorable wear properties with possibility of prevention of dislocation in long-term clinical use.

Abstract. Cemented total hip arthroplasty (THA) in the younger patient has historically been associated with higher wear and revision rates. We carried out a retrospective study of a prospectively collected database of patients at Wrightington hospital undergoing cemented THA under 55 years of age to determine acetabular wear and revision rates. Between August 2005 and December 2021 a cohort of 110 patients, 56 males and 54 females, underwent Cemented Total Hip Replacement through a posterior approach. Mean age at operation was 50yrs (35–55). The mean follow up was 6 years 9 months (0–16 years). 3 patients were lost to follow-up. Of the remaining 107 patients, Conventional and cross lined polyethylene were used in 54 and 53 patients respectively. Ceramic heads were used in 102 patients. 22.225mm and 28mm heads were used in 60 and 47 patients respectively. Clinical outcomes were assessed by Merle d'Aubigne and Postel scores which showed significant functional improvement. Linear wear was measured on plain radiographs using TRAUMA CAD and cup loosening was assessed by classification of Hodgkinson et al. No cases were revised during the observed follow up period. The mean wear rate in conventional and crosslinked polyethylene cups were 2.31mm (0.1–4.6) and 1.02mm (0.1–2.6) respectively. Cemented THA with both conventional and crosslinked polyethylene provides excellent survival rates in adults under the age of 55 years and crosslinked polyethylene may further improve these results due to improved wear rates

Scapular notching is a common problem following reverse shoulder arthroplasty (RSA). This is due to impingement between the humeral polyethylene cup and scapular neck in adduction and external rotation. Various glenoid component strategies have been described to combat scapular notching and enhance impingement-free range of motion (ROM). There is limited data available detailing optimal glenosphere position in RSA with an onlay configuration. The purpose of this study was to determine which glenosphere configurations would maximise impingement free ROM using an onlay RSA prosthesis. A three-dimensional (3D) computed tomography (CT) scan of a shoulder with Walch A1, Favard E0 glenoid morphology was segmented using validated software. An onlay RSA prosthesis was implanted and a computer model simulated external rotation and adduction motion of the virtual RSA prosthesis. Four glenosphere parameters were tested; diameter (36mm, 41mm), lateralization (0mm, 3mm, 6mm), inferior tilt (neutral, 5 degrees, 10 degrees), and inferior eccentric positioning (0.5mm, 1.5mm. 2.5mm, 3.5mm, 4.5mm). Eighty-four combinations were simulated. For each simulation, the humeral neck-shaft angle was 147 degrees and retroversion was 30 degrees. The largest increase in impingement-free range of motion resulted from increasing inferior eccentric positioning, gaining 15.0 degrees for external rotation and 18.8 degrees for adduction. Glenosphere lateralization increased external rotation motion by 13. 6 degrees and adduction by 4.3 degrees. Implanting larger diameter glenospheres increased external rotation and adduction by 9.4 and 10.1 degrees respectively. Glenosphere tilt had a negligible effect on impingement-free ROM. Maximizing inferior glenosphere eccentricity, lateralizing the glenosphere, and implanting larger glenosphere diameters improves impingement-free range of motion, in particular external rotation, of an onlay RSA prosthesis. Surgeons’ awareness of these trends can help optimize glenoid component position to maximise impingement-free ROM for RSA. Further studies are required to validate these findings in the context of scapulothoracic motion and soft tissue constraints

Unlike conventional radiographic methods, the newly introduced EOS system provides simultaneously-synchronized anteroposterior (AP) and true-lateral (LAT) x-ray images. EOS offers considerable potential for calculating parameters such as true femoral and acetabular angular positioning, impingement sites, and also for measuring wear in polyethylene cups. In this study we used THA wear-simulation fixtures to assess 3D-wear in polyethylene cups using EOS algorithms. Material and methods. A validated phantom apparatus was used to simulate values of three-dimensional wear, controlled in the 3 directions (antero-posterior, medio-lateral, cranio-caudal) using micrometers. (Figure 1). 24 simulations of wear with controlled amplitudes and directions were imaged using the biplane EOS slot-scanning system. Wear amplitudes were between 0 and 3464 μm. Using dedicated software, wear was measured by a 2D/3D matching of 3D spheres onto the 2D frontal and lateral radiographs, allowing the determination of the 3D coordinates of both the cup and femoral head centers and thus the calculation of a 3D wear vector. (Figure 2). Measured wear vector were compared to real wear vectors in terms of amplitude and direction.3D wear vectors were measured twice by 3 independent observers (for a total of 144 measurements) in order to evaluate intra- and inter-observer reliability. Results. There was a strong correlation between the measured wear amplitude and the real wear amplitude (Pearson's r = 0,99). Mean error when comparing wear measurement amplitude with real wear amplitude was 356 μm (SD = 127 μm). None of the 144 measurements presented an error over 1 mm. The accuracy of wear direction evaluation was highly correlated with wear amplitude (Spearman's rho = 0,98), the measurement of 3D wear direction presenting an accuracy better than 15° for wear amplitudes over 1,5 mm. Intra-observer errors for wear amplitude were between 138 μm and 221 μm depending on the observer. Inter-observer error for wear amplitude was 333 μm. Conclusion. EOS imaging is a promising technology for measuring 3D-wear in polyethylene cups. Further works are underway to compare the EOS algorithms with conventional methods

Introduction. The performance of total hip replacement (THR) devices can be affected by the quality of the tissues surrounding the joint or the mismatch of the component centres during hip replacement surgery. Experimental studies have shown that these factors can cause the separation of the two components during walking cycle (dynamic separation) and the contact of the femoral head with the rim of the acetabular liner (edge loading), which can lead to increased wear and shortened implant lifespan. 1. There is a need for flexible pre-clinical testing tools which allow THR devices to be assessed under these adverse conditions. In this work, a novel dynamic finite element model was developed that is able to generate dynamic separation as it occurs during the gait cycle. In addition, the ability to interrogate contact mechanics and material strain under separation conditions provides a unique means of assessing the severity of edge loading. This study demonstrates these model capabilities for a range of simulated surgical translational mismatch values, for ceramic-on-polyethylene implants. Methodology. The components of the THR were aligned and constrained as illustrated in Figure 1. CAD models of commercially available implant geometries were used (DePuy Synthes, Leeds, UK) modified for model simplicity by removing anti-rotation features. The polyethylene cup liner was given elastic-plastic behaviour. An axial load following the Paul cycle pattern (5 repetitive cycles) with maximum of 3KN and swing phase load of 0.3KN, was applied through the cup holder. The effect of translational mismatch was implemented by using a spring element connected to the cup unit on the lateral side. The spring was compressed by a fixed amount to replicate a degree of medial-lateral mismatch of the components. The instantaneous resultant force vector dictated the dynamic sliding behaviour of the cup against the head. In this study, translational medial-lateral mismatch values of 1, 2, 3 and 4mm were used and the medial-lateral dynamic separation, contact pressure maps and plastic strain were recorded. Results. The highest level of dynamic separation is achieved when the minimum axial load (during swing phase) is applied. The dynamic separation increases as the surgical translation mismatch increases (figure 2), with values over 0.5mm (radial clearance) representing cases where the head is in contact with the rim of the cup. Maximum separation occurred towards the end of the swing phase. Plots of the shape of the contact pressure at that point can be seen in Figure 3. Only the 4mm mismatch created substantial plastic deformation. Conclusion. The finite element model was able to predict medial-lateral separation as it occurred dynamically in the gait cycle, including cases where the femoral head was in contact with the rim of the cup. The increase in medial-lateral separation with increased translational mismatch was in broad agreement with existing experimental data. 2. Substantial plastic deformation was only seen in cases where the translational mismatch caused the femoral head to be in contact with the rim of the polyethylene cup

Dislocation after Total Hip Replacement (THR) remains the second most common reason for revision in the Australian Orthopaedic Association National Joint Replacement Registry (AOA NJRR) and is the most common reason out to 3 years post operatively. There are many causes and associations of dislocation, including patient behaviour and (often unrecognized) spinal pathology leading to adverse component orientation. Femoral ball head size along with the head:neck ratio and the head:cup ratio are all important. Data from the AOA NJRR demonstrates a lower revision rate for dislocation with larger head sizes in all bearing surface combinations. Data from the AOA NJRR confirms that the revision rate for replaced hips using non cross-linked polyethylene cups increases along with the head size, but this is not seen with cross-linked polyethylene cups. THR using cross-linked polyethylene has a lower revision rate than THR using non cross-linked polyethylene, this difference is evident after only 3 months and the difference increases with time. The 12 year Cumulative Revision Rate (CRR) is 5.3% compared to 10.1%. This lower rate of revision is due to a reduced revision rate for both dislocation and loosening/lysis. The revision rate for dislocation at 1 year was 0.4% for THR with cross-linked polyethylene and 0.7% with non cross-linked polyethylene. Head sizes of 32mm and greater were used in 56.5% of THR with cross-linked polyethylene but only 12.7% of those with non cross-linked polyethylene. There was no difference in the revision rate for dislocation when head sizes of 32mm and less were compared, the difference was due to the higher proportion of larger head sizes used with cross-linked polyethylene. However there are reasons why the benefits of larger femoral ball heads may not increase with increasing head size, this is chiefly because of altered cup subtended angles (and femoral head offset) geometries incorporated into cup and liner designs, especially the ceramic on ceramic bearings. Larger head sizes may also increase the risk of taper disease, especially with smaller tapers and softer metal alloys. Exchangeable neck prostheses, introduced to allow surgeons more control over orientation and offset have a higher revision rate in the AOA NJRR and this increased revision rate is due to prosthetic dislocation as well as loosening/lysis

Little is known about the relationship between head-neck corrosion and its effect on the periprosthetic tissues and distant organs of patients hosting well-functioning devices. The purpose of this study was to investigate in postmortem retrieved specimens the degree and type of taper damage, and the corresponding histologic responses in periprosthetic tissues and distant organs. Fifty postmortem THRs (34 primaries, 16 revisions) retrieved after 0.5 to 26 years were analyzed. Forty-three implants had a CoCrMo stem and seven had a Ti6Al4V stem. All heads were CoCrMo and articulated against polyethylene cups (19 XLPE, 31 UHMWPE). H&E sections of joint pseudocapsules, liver, spleen, kidneys and lymph nodes were graded 1–4 for the intensity of various inflammatory cell infiltrates and tissue characteristics. Corrosion damage of the taper surfaces was assessed using visual scoring and quantitated with an optical coordinate measuring machine. SEM analysis was used to determine the acting corrosion mode. Polyethylene wear was assessed optically. The majority of tapers had minimal to mild damage characterized by local plastic deformation of machining line peaks. Imprinting of the stem topography onto the head taper surface was observed in 18 cases. Column damage on the head taper surface occurred in three cases. All taper surfaces scored moderate or severe exhibited local damage features of fretting and/or pitting corrosion. Moderate or severe corrosion of the head and/or trunnion was present in nine hips. In one asymptomatic patient with bilateral hips, lymphocyte-dominated tissue reactions involving perivascular infiltrates of lymphocytes and plasmacytes were observed. In this patient, mild, focal lymphocytic infiltrates were also present in the liver and kidneys, and there was focal histiocytosis and necrosis of the para-aortic lymph nodes. These two implants, which had been in place for 58.6 and 60.1 months, had severe intergranular corrosion of the CoCrMo trunnion, and column damage and imprinting on the head taper. In the other 41 hips, macrophage responses in the joint pseudocapsule to metallic and/or polyethylene wear particles ranged widely from minimal to marked. Focal necrosis in the pseudocapsules of 12 arthroplasties was related to high concentrations of CoCrMo, TiAl4V, TiO, BaSO4 and polyethylene wear particles. High concentrations of these particles were also detected in para-aortic lymph nodes. Rare to mild macrophages were observed in liver and spleen. This is a comprehensive study of wear and corrosion within well-functioning postmortem retrieved THRs, and the resulting local and distant tissue reactions. One of eight patients with moderate or severe corrosion did have a subclinical inflammatory response dominated by lymphocytes after five years. To what extent such an inflammatory process might progress to become symptomatic is not known. Ionic and particulate products generated by corrosion disseminated systemically. The minor lymphocytic infiltrate in the liver and kidneys of one subject with bilateral severely corroded head-neck junctions might suggest possible metal toxicity. The diagnosis of adverse tissue reactions to corrosion of modular junctions can be challenging. Postmortem retrieval studies add to our understanding of the nature and progression of lymphocyte-dominated adverse local and potentially systemic tissue reactions to corrosion of modular junctions

Introduction. One of the known mechanisms which could contribute to the failure of total hip replacements (THR) is edge contact. Failures associated with edge contact include rim damage and lysis due to altered loading and torques. Recent study on four THR patients showed that the inclusion of pelvic motions in a contact model increased the risk of edge contact in some patients. The aim of current study was to determine whether pelvic motions have the same effect on contact location for a larger patient cohort and determine the contribution of each of the pelvic rotations to this effect. Methods. Gait data was acquired from five male and five female unilateral THR patients using a ten camera Vicon system (Oxford Metrics, UK) interfaced with twin force plates (AMTI) and using a CAST marker set. All patients had good surgical outcomes, confirmed by patient-reported outcomes and were considered well-functioning, based on elective walking speed. Joint contact forces and pelvic motions were obtained from the AnyBody modelling system (AnyBody Technologies, DK). Only gait cycle regions with available force plate data were considered. A finite element model of a 32mm head on a featureless hemispherical polyethylene cup, 0.5mm radial clearance, was used to obtain the contact area from the contact force. A bespoke computational tool was used to analyse patients' gait profiles with and without pelvic motions. The risk of edge contact was measured as a “centre proximity angle” between the cup pole and centre of the contact area, and “edge proximity angle” between the cup pole and the furthest contact area point away from the pole. Pelvic tilt, drop and internal-external rotation were considered one at a time and in combinations. Results. In eight out of 10 patients, the addition of pelvic motions decreased the risk of edge contact during toe-off. There was up to 6° reduction in the proximity angles when pelvic motions were introduced to the gait cycle. In six out of 10 patients, the addition of pelvic motions resulted in an increase in the risk of edge contact during heel-strike with up to 6° increase in the proximity angles. For all patients where these effects were seen, sagittal pelvic tilt was a substantial contributor. Conclusion. The results of this study suggest that pelvic motion play an important role in contact location in THR bearings during loading phase. Both static and dynamic pelvic tilt contribute to the variability in the risk of edge contact. Further tests on larger patient cohorts are required to confirm the trends observed. The outcomes of this study suggest that pre-clinical mechanical and tribological testing of THRs should consider the role of pelvic motion. The outcomes also have implications for establishing surgical positioning safe zones, which are currently based only on risk of dislocation and severe impingement

Introduction. Little is known about the relationship between head-neck corrosion and its effect on periprosthetic tissues and distant organs in the majority of patients hosting apparently well-functioning devices. We studied the degree and type of taper damage and the histopathologic response in periprosthetic tissue and distant organs. Methods. A total of 50 contemporary THRs (34 primary, 16 revision) retrieved postmortem from 40 patients after 0.4–26 years were studied. Forty-three femoral stems were CoCrMo and 7 were Ti6Al4V. In every case, a CoCrMo-alloy head articulated against a cementless polyethylene cup (19 XLPE and 31 UHMWPE). H&E and IHC sections of the joint pseudocapsules and liver were graded 1–4 for the intensity of various inflammatory cell infiltrates and tissue necrosis. The nature of the tissue response in the joint capsule, liver, spleen, kidneys and lymph nodes was assessed. Wear and corrosion products in the tissues were identified using SEM and EDS. Taper surfaces were graded for corrosion damage using modified Goldberg scoring and examined by SEM to determine the acting corrosion mode. Correlations between damage scores and the histologic variables were generated using the Spearman test. Results. No correlation was seen between taper damage scores and the macrophage response in the joint pseudocapsule. The distribution of corrosion scores for heads and femoral trunnions is shown in Figure 1. Moderate or severe corrosion of the head and/or trunnion was present in 9 hips (8 CoCr/CoCr and 1 CoCr/TiAlV). One patient with bilateral hips had local ALVAL-like lymphocyte-dominated tissue reactions (Figure 2) and mild focal lymphocytic infiltrates in the liver and kidneys (Figure 3). This was associated with severe intergranular corrosion of the CoCrMo trunnion and column damage on the head taper. Particle-laden macrophages in pseudocapsules were significantly correlated with liver macrophages (r=.382, p=0.012) and liver lymphocytes (r=.367, p=0.013). Pseudocapsule macrophage responses to metallic and/or polyethylene wear particles ranged widely from minimal to marked. Focal tissue necrosis was related to high concentrations of particulate wear debris. A minimal number of metallic particle-laden macrophages were also detected in the liver and spleen; and macrophage granulomas were present in para-aortic lymph nodes, especially in revision cases. DISCUSSION. The generation of metal ions and particulates at corroded CoCrMo heads and CoCrMo or Ti6Al4V trunnions was a significant contributor to the presence of perivascular lymphocytes within the joint pseudocapsule, with 1 patient showing a histologic pattern consistent with ALVAL. Patient factors and the rate of corrosion are among variables influencing whether an ALVAL-type reaction will develop and whether or not it will become symptomatic. Macrophages in the joint pseudocapsules were positively correlated with inflammatory cells in the liver. In this study, the intensity of inflammatory infiltrates in distant organs was mild. However, several cases of organ dysfunction have been reported in association with catastrophic wear of CoCrMo components. It continues to be essential to minimize the generation of metal ions and particulates and to improve strategies for identifying and managing patients exposed to high levels of degradation products. For any figures or tables, please contact the authors directly

Introduction. Wear of the ultra high molecular weight polyethylene (UHMWPE) cup and the resulting loosening has been shown to limit the long-term results of the Charnley low-frictional torque arthroplasty (LFA). Factors affecting wear rates have been studied: level of patient activity, effective roughness of the stainless steel head, impingement and the possible variations in wear characteristics of UHMWPE. Since patients' activity level cannot be predicted or modified, alternative materials were examined. Methods and Results. The Charnley 22.225 mm diameter head of alumina ceramic in combination with chemically cross-linked polyethylene cup has now reached over 23 years of clinical and radiographic follow-up. Of the initial 17 patients (19 hips) in the study, 4 patients (4 hips) have died, 1 hip has been revised for deep infection and 3 patients (3 hips) are unable to attend follow-up due to medical problems unrelated to the hip. Nine patients (11 hips) are still attending follow-up at a mean of 22 years 5 months (21 year 3 months-23 years 6 months). The mean age at surgery in this group was 47 years (26-58) and the mean weight 81kgs (54-102). The mean penetration rate was 0.02mm/year and none have exceeded 0.41mm total penetration. Conclusion. Since the problem of cup wear and loosening is mechanical rather than biological the long-term solutions are more likely to come from materials rather than radical changes of design of methods of component fixation

Uncontained acetabular defects with loss of superior iliac and posterior column support (Paprosky 3B) represent a reconstructive challenge as the deficient bone will preclude the use of a conventional hemispherical cup. Such defects can be addressed with large metallic constructs like cages with and without allograft, custom tri-flange cups, and more recently with trabecular metal augments. An underutilised alternative is impaction bone grafting, after creating a contained cavitary defect with a reinforcement mesh. This reconstructive option delivers a large volume of bone while using a small-size socket fixed with acrylic cement. Between 2006 and 2014, sixteen patients with a Paprosky 3B acetabular defect were treated with cancellous, fresh frozen impaction grafting supported by a peripheral reinforcement mesh secured to the pelvis with screws. A cemented all polyethylene cup was used. Preoperative diagnosis was aseptic loosening (10 cemented and 6 non-cemented). The femoral component was revised in 9 patients. Postoperative course consisted of 3 months of protected weight bearing. Patients were followed clinically and radiographically. One patient had an incomplete postoperative sciatic palsy. After a mean follow up of 40 months (24 to 104) none of the patients required re-revision. One asymptomatic patient presented with aseptic loosening 9 years postoperatively. Hardware failure was not observed. All patients had radiographic signs of graft incorporation and bone remodeling. There were no dislocations. The early and mid-term results of revisions for large acetabular defects with this technique are encouraging. Reconstitution of hip center of rotation and bone stock with the use of a small-size implant make this technique an attractive option for these large defects. Longer follow-up is needed to assess survivability

Mid and long-term follow-up of Charnley total hip arthroplasty (THA) demonstrated good functional results with 85% survivorship at 25-year follow-up. However dislocation still remains an unsolved problem. Dislocation may occur all along the patient and implant life. The aim of this study is to answer the question: does Dual Mobility Cup (DMC) decrease the dislocation risk? . Method. : We report comparative results at ten years of follow-up of 2 groups of primary cemented Charnley-type THA, one with a standard polyethylene cup (group 1, n=215) and the other one with a DMC (group 2, n=105). . Results. : In group 1, twenty-six dislocations (12.9%) occurred. In group 2 only one dislocation (0.9%) occurred. This dislocation was successfully reduced by close reduction, without any recurrence. This difference was statistically significant (p=0.0018). In group 1, reason for revision was recurrent dislocation in twenty one cases. Five patients have been revised for other reasons. The global revision rate was 12.9%. In group 2, two patients needed revision surgery for aseptic loosening. The global revision rate was 2.1%. This difference was statistically significant (p=0.0054). The goal was reached for the patients of group 2 who had more risks factors of dislocation (age, aetiology, ASA and Devane scores) than those of group 1. When using a DMC, we observed a low rate of dislocation in primary THA (0.9%). This surgical choice seems to be a secure and effective technique in Charnley-type THA, especially in a high risk population

Malpositioning still occurs in total hip arthroplasty (THA). As a result of mal-orientation, THA bearing can be subjected to edge loading. The main objective of the study was to assess if the wear rate of ceramic-on-ceramic and metal-on-polyethylene increases under edge loading conditions and to determine which of the most commonly used hip bearings is the most forgiving to implant mal-orientation. Materials and methods. Two different polyethylenes (UHMWPE and vitamin E blended HXLPE) and ceramics (pure aluminum PAL and alumina-toughened zirconia ATZ) were tested with a hip simulator and compared to metal-on-metal results. The inclination angle was selected at 45°, 65° and 80°. In addition, the ceramic-on-ceramic barings were tested at conditions that produced microseparation. Results. Contrary to metal-on-metal that is highly susceptible to edge loading, the wear rate of ceramic-on-ceramic and metal-on-polyethylene articulations does not increase with increasing cup inclination. In fact, the polyethylenes showed a contra-intuitive behaviour as its wear rate decreased slightly but significantly with increasing inclination angle. This behaviour can be explained when looking closely at the contact stresses and areas. (Figure 1 shows the wear area of the vitamin E blended HXLPE at 45° and figure 2 at 80° cup inclination). The newest biomaterials, vitamin E blended HXLPE and ATZ, showed markedly lower wear rates compared to their conventional counterparts, UHMWPE and PAL. The ATZ ceramic-on-ceramic articulation showed the lowest wear rate (even when microseparation is included) of all tested pairings, but the new vitamin-doped HXLPE seems to be the most forgiving materials when it comes to implant mal-orientation. It shows low wear rate even at an extremely high cup inclination angle. Therefore, a surgeon that discovers a mal-positioned polyethylene cup at the first post-op X-ray will not need to worry unduly about increased wear (but “only” about a potential dislocation)

Background. Scapular notching causes glenoid bone loss after a reverse total shoulder arthroplasty (rTSA). The goal of this study was to assess the influence of prosthesis design on notching. Methods. Prospective, single surgeon cohort. Two different rTSA designs were consecutively implanted and compared: 25 Delta III rTSAs and 57 Delta Xtend rTSAs in 80 patients. Notching (Nerot 0–4) was assessed at 24 months follow-up. Patient dependent variables, surgical technique and implant geometry were assessed. Multivariate binary logistic regression was used to select the strongest independent predictors of notching. Results. The Delta III showed significantly more notching than the Delta Xtend: 72% and 23% respectively, p<0.001. The extent of notching was comparable. One patient (Delta III) needed revision for notching-associated glenoid loosening. Only 3 variables were significantly associated with notching in multivariate analysis: glenosphere overhang (R square 0.65), prosthesis-scapular neck angle (PSNA, R square 0.18) and humeral cup depth (R square 0.05), predicting 88% of notching cases. The corresponding odds ratios were 0.15 (95% CI 0.05–0.44) for 1 mm extra overhang, 8.4 (95% CI 2.0–35.6) for 10 degrees increase in PSNA and 7.6 (95% CI 1.3–43.3) for 1 mm extra cup depth. Surgical technique related variables, including peg-glenoid rim distance and PSNA, were comparable in both design groups. Conclusion. The key to prevent notching was to utilise the design features that maximise glenosphere overhang. Therefore, as a rule of thumb the baseplate should be positioned as inferior as possible. Minor contributions came from PSNA (patient anatomy/surgical technique) and polyethylene cup depth (also design). One patient required early revision for notching associated baseplate loosening. Long term follow-up is indicated to assess the effect of notching on prosthesis survival and outcome after revision

Introduction. Technological advances in the processing of polyethylene have led to improved survivorship of total hip arthroplasty. The purpose of this study was to determine if a second generation highly cross-linked polyethylene could improve upon wear rates compared to conventional and first generation cross-linked polyethylene in patients undergoing primary total hip arthroplasty. Methods. Linear and volumetric wear rates of a second generation highly cross-linked polyethylene were evaluated following primary total hip arthroplasty. There were 44 patients with an average age of 68.6 years and mean follow-up of 5.3 years. Patients were evaluated at six weeks, one, two and five years. Wear rates were determined from digitized AP Pelvis radiograph by an independent observer using Martell's software. Acetabular inclination and femoral head size were also evaluated to determine variability in wear rates. Results. The mean linear wear rate for the entire group was 0.015mm/year (±0.055). There was a 64% decrease in linear wear rate when compared to a first generation highly cross-linked polyethylene from the same institution. There was a 90% decrease in wear rate compared to conventional polyethylene. There were no differences in the linear wear rate between the 32mm vs. larger head sizes (36mm and 40mm). However, there was a 30% increase in volumetric wear rate with larger head sizes. The mean wear rate in patients with cup inclination less than 45 degrees was 0.006mm/year compared with 0.024mm/year for those with an inclination greater than 45 degrees. The amount of linear wear was increased by 4 times in patients with a cup inclination of greater than 45 degrees. There was no evidence of any osteolysis in this group of patients. Conclusion. Our data with a mean follow-up of 5.3 years, using a second generation highly cross-linked polyethylene, demonstrates a dramatic decrease in incidents of linear wear compared to conventional polyethylene and first generation highly cross-linked polyethylene (Figure 1). Of concern is the higher volumetric wear rate noted with larger head sizes and increased linear wear rates with cup inclination angles of greater than 45 degrees. Despite improvements in wear rates using a second generation highly cross-linked polyethylene, cup orientation and choice of head size play significant roles in implant survivorship

Long-term prospective RCT comparing hemiarthroplasty (HEMI) and total hip arthroplasty (THA) for the treatment of intracapsular neck of femur fracture. 81 previously mobile, independent, orientated patients were randomised to receive THA or HEMI after sustaining a displaced neck of femur fracture. Patients were followed up with radiographs, Oxford hip score (OHS), SF-36 scores and their walking distance. At a mean follow up of 8.7 years, overall mortality following THA was 32.5% compared to 51.2% following HEMI (p=0.09). Following THA, patients died after a mean of 63.6 months compared to 45 months following HEMI (p=0.093). Patients with THA walked further and had better physical function. No HEMIs dislocated but three (7.5%) THAs did. Four (9.8%) HEMI patients were revised to THA, but only one (2.5%) THA required revision. All surviving HEMI patients had acetabular erosion and all surviving THA patients had wear of the cemented polyethylene cup. Patients with THA have better function in the medium-term and survive longer

We report the outcome at a minimum of 10 years follow-up for 80 polished tapered stems performed in 53 patients less than 35-years-old with a high risk profile for aseptic loosening. Forty-six prosthesis were inserted for inflammatory hip arthritis and 34 for avascular necrosis. The mean age at surgery was 28 years in the inflammatory arthritis (17–35) and 27 years in the avascular necrosis (15–35) patients. At a mean follow-up of 14.5 years in the inflammatory arthritis group and 14 years in the avascular necrosis group respectively, survivorship of the 80 stems with revision of the femoral component for any reason as an endpoint was 100 % (95 % CI). Re-operation was because of failure of four metal-backed cups, 3 all polyethylene cups and one cementless cup. None of the stems were radiographically loose. All but two femoral components subsided within the cement mantle to a mean of 1.2 mm (0 tot 2.5) at final follow-up. Periarticular osteolysis was noted in 4 femurs in zone 7. This finding was associated with polyethylene wear and was only seen in those hips that needed revision for a metal backed cup loosening. Our findings show that the polished tapered stem has excellent medium-term results when implanted in young patients with high risk factors for aseptic loosening

We present 346 consecutive revision procedures for aseptic loosening with acetabular impaction bone grafting (AIBG) and a cemented polyethylene cup. Defects were contained with mesh alone. Mean follow up of 6.6 years, range 8 days-13 years. The Oxford Hip (OHS) and Harris Hip (HHS) scores were collected prospectively. Radiological definition of cup failure was either > 5mm displacement, or > 5° rotation. Cox regression analysis was performed on ten separate patient and surgical factors to determine their significance on survivorship. Kaplan Meier survivorship at 10 years (42 cases remaining at risk) for aseptic loosening was 87% (95% confidence Interval (CI): 81.6 to 92.2) and 85.6% (95% CI: 80.3 to 90.9) for all revisions. These results are comparable to other reported series utilising AIBG. However, there were 88 cases (25%) that exceeded the radiological migration parameters, but their functional scores were not significantly different to the non-migrators: OHS p=0.273, HHS p=0.16. The latest post-operative mean OHS was 33 (SD 10.66). Female gender (p=0.039), increasing graft thickness (p=0.006) and the use of mesh (p=0.037) were significant risk factors for revision, but differing techniques in graft preparation, including artificial graft expanders (p=0.73), had no significant effect when analysed using Cox regression

Purpose:. Crosslinking of polyethylene has become synonymous with longevity in total hip replacement. In the USA 70–85% of all polyethylene cups underwent crosslinking since 2008. Three publications appeared in the autumn 2011 volume of the “SA Orthopaedic Journal,” on the 10–33 year follow-up of the original SA crosslinked implant. The purpose of this study is to illustrate and confirm statistically, the improvement of the bone cement interface, provided that wear of polyethylene can be reduced to an absolute minimum. Method:. Complete follow-up included Merle D'Aubigne clinical follow-up and radiological studies of the interface. Interpretation of radiological measurements was according to the D.M. (Digital Magnification) method, as published in 2007. This information was digitally analysed by the Department of Statistics, University of Pretoria. Follow-up was at six months post op and again at end of study. All cups were crosslinked with fixed-dose Gamma-rays, in a saturated acetylene environment, acting as mediating gas. This resulted in enhanced crosslinking in the superficial 300µ of the pre-manufactured implant. Result:. Of the 97 cases studied, 58 showed no interface changes at all, while 26 cases had deteriorated moderately and of which only 7 cases needed revision as result of polyethylene wear of >1 mm. The correlation between wear and interface deterioration was statistically proven with excellent p-values. Most interesting was the third group of 16 cases (16.6%) that also showed no cup wear, but additionally displayed definite radiological signs of interface improvement. Conclusion:. We conclude that the correlation between cup wear and interface deterioration is well proven and documented in this study. We can now state with confidence that polyethylene wear has to be minimised at all cost. Improvement of the interface is a new phenomenon which can only be achieved under extremely low wear conditions, and promises excellent longevity of the arthroplasty