Introduction. The continued improvement of ceramic materials for total hip arthroplasty led to the development of Zirconia and Zirconia toughened Alumina materials such as BIOLOX® delta. Zirconia exists in a tetragonal phase in new ceramic heads and can transform to a monoclinic phase in response to loading giving the material improved fracture toughness. It is known that surface transformation occurs in this material under hydrothermal conditions (i.e. in vivo condition), and ISO standards recommend parts are artificially aged prior to testing to include any effect of surface transformation on new designs. Accelerated aging procedures have been used to predict the amount of phase transformation that will occur in vivo, but validation of these models requires the study of retrieved hip joints. Here 26 BIOLOX® delta retrievals are analysed to determine the degree of phase transformation that occurs in vivo. The levels of phase transformation measured are compared with those predicted based on accelerated aging tests. Methods. Twenty-six retrieved BIOLOX® delta (CeramTec AG, Germany) femoral heads were investigated. Retrievals were obtained after implantation of between 1 month and 7 years with an average follow-up of 1.5 years. All retrievals were from ceramic-on-ceramic hip joints that were implanted between 2004 and 2012. Mean patient age was 69 years (range 48–87 years). Raman spectra were collected using a confocal Raman spectrometer (WITec Gmbh, Germany) a laser wavelength of 532nm, a 50× objective and a 100μm pinhole. Twenty-five measurements were made on each retrieval at random locations outside any visible wear scars and inside visible wear scars. The average monoclinic content was calculated based on the method of Clarke and Adar [1]. For comparison 5 new BIOLOX® delta femoral head resurfacings were measured using the same procedure. Results. The average monoclinic content of the new heads was 5%±2%. For unworn areas of the retrievals this increased to 23%±9% with the highest monoclinic content measured at 42%. There was no statistical correlation between implantation time and monoclinic content in the unworn areas. In worn areas of the retrievals the monoclinic content was higher and varied between 13% and 51%. Discussion. This is the largest set of retrieved BIOLOX® delta heads to be examined for changes in monoclinic content building on the work of Affatato et al. [2] who analysed 5 retrievals. All retrievals have a higher level of phase transformation than new heads in the unworn areas showing that hydrothermal aging does take place in the body. The results also show that on average there is more monoclinic transformation in worn areas and hence the material toughening effect of the Zirconia phase is utilised. The mean phase transformation found in vivo matched the 23%±5% reported as occurring under the conditions described in the ISO standard for hydrothermal aging [3]. However, the ISO standard is thought to be equivalent to 40 years in vivo whilst the retrievals measured had a mean follow-up of 1.5 years

Two types of ceramic materials currently used in total hip replacements are third generation hot isostatic pressed (HIPed) alumina ceramic (commercially known as BIOLOX®forte, CeramTec) and an alumina matrix composite material consisting of 75% alumina, 24% zirconia, and 1% mixed oxides (BIOLOX®delta, CeramTec). The aim of this study is to compare BIOLOX delta femoral heads to BIOLOX forte femoral heads revised within 2 years in vivo. Ceramic bearings revised at one center from 1998 to 2010 were collected (61 bearings). BIOLOX delta heads (n=11) revised between 1–33 months were compared to BIOLOX forte femoral heads with less than 24 months in vivo (n=20). The surface topography of the femoral heads was measured using a chromatically encoded confocal measurement machine (Artificial Hip Profiler, RedLux Ltd.). The median time to revision for BIOLOX delta femoral heads was 12 months, compared to 13 months for BIOLOX forte femoral heads. Sixteen out of 20 BIOLOX forte femoral heads and 6 out of 11 BIOLOX delta femoral heads had edge loading wear. The average volumetric wear rate for BIOLOX forte was 0.96 mm3/yr (median 0.13 mm3/yr), and 0.06 mm3/yr (median 0.01 mm3/yr) for BIOLOX delta (p=0.03). There was no significant difference (p>0.05) in age, gender, time to revision or femoral head diameter between the two groups. Early results suggest less volumetric wear with BIOLOX delta femoral heads in comparison to BIOLOX forte femoral heads

Since 2006 we have started to implant modular stelus, ceramic articolar component and Delta cotilus (PF 2006.2007 and TT since 2008) in hip artroplastic of young patients. 53 implantations (4 cases bilateral). Association with conic stelus (14th different shapes from 13 to 26) with trocanterical modulus that permits a good compliance studing each cases (offset-AR-lever-arm). We have found a good resolution using ceramic as matherial in articolar joint because reaching a very high level of satisfaction both for surgeons and for patients outfits. The Delta TT Lima has a titanium trabecular surface that offers a very good primary stability and a very high level in bone integration. The dedicated instrumentary, the design and the matherial high quality are the bases for a good resistance and a good articolar stability. Medium age of patients was 51 y.o. (from 33 to 66 y.o); follow up has been made at the 1st year and the 6th year. Results were evaluated following HHS guide line. Main treated pathologies were: primary arthrosis (9 cases); DCA (21 cases), post thraumatic arthrosis (9 cases), OA (8 cases), hip fractures (6 cases)

INTRODUCTION. Managing severe periacetabular bone loss during revision total hip arthroplasty (THA) is a challenging task. Multiple treatment options have been described. Delta Revision Trabecular Titanium™ (TT) cup is manufactured by Electron Beam Melting (EBM) technology that allows modulating cellular solid structures with an highly porous structure were conceived to rich the goals of high bone ingrowth and physiological load transfer. The caudal hook and fins ensure additional stability and the modular system allows the surgeon to treat bone defects in the most complex revisions. Entirely modular, the system can meet all intra-operative needs thanks to a customized implant construction. The aim of this prospective study is to evaluate the short to mid-term clinical and radiographic outcomes of this acetabular revision cups. MATERIALS AND METHODS. We prospectively assessed clinical and radiographic results of 31 cases of acetabular revisions that were performed from June 2007 and March 2012 by Delta TT Lima Revision system. The mean age of patients was 69.5 years (range 29–90). The causes of revision were aseptic loosening in 22 cases (71.0%), periprosthetic acetabular fractures in 4 cases (13.0%), multiple dislocation of the primary implant in 3 cases (9.6%) and outcome of infection in 2 cases (6.4%). Stem revision was performed in 11 cases (35,4%). In 24 cases bone impaction grafting was used to fill cavitary defects (Paprosky 2B-3A); in 7 cases TT augments were used with the same aim. The average follow-up was 32 months (range 12–69). RESULTS AND CONCLUSIONS. No major complications were observed. The mean HHS significantly increased from 39.9 (range 17–60) preoperatively to 86.5 (range 65–100) at the last follow-up examination. The implanted cups were radiographically stable at the last follow-up visit without radiolucent lines or periprosthetic osteolysis. Trabecular Titanium showed a high capacity of osseointegration, providing excellent results in short to mid-term follow-up. The impaction grafting has demonstrated effective restoration of bone stock and no radiographic evidence bone resorption (Fig. 1). DISCUSSION. Delta Revision TT is a good solution for acetabular revision surgery even when there are cavitary and segmental bone defects. It is possible to restore muscle tension and correct anatomical impairments, while enhancing implant stability and minimising the risk of dislocation

Objectives. Total hip replacement is increasingly being conducted in younger and more active patients, so surgeons often use bearing surfaces with improved wear characteristics, such as ceramic on ceramic. The primary objective of this study was to determine if survivorship for a BIOLOX® delta ceramic on delta ceramic couple used with the PROCOTYL® L acetabular cup is significantly different from all other cementless cups in a large arthroplasty registry. The secondary objective of this study was to analyze patient reported outcomes measures (PROMs) of the subject cup with a minimum five year follow-up. Methods. Patient demographics and survivorship data was collected from the National Joint Registry of England, Wales, Northern Ireland, and the Isle of Man (NJR) database for all total hip replacements performed with the PROCOTYL® L cup used in combination with a delta-on-delta articulation, as well as for all other cementless cups. Survivorship data was compared for all revisions and cup revisions only and data was adjusted to exclude metal on metal articulations. The hazard ratio of the subject system to all cementless cups was also calculated with the Cox Proportional Hazards model. Patients with the subject components implanted for a minimum of five years completed Oxford Hip, EQ-5D, and EQ VAS score questionnaires. Results. The patient demographic data collected for the subject components and all cementless cups is provided in Figure 1. Six-year survivorship for the subject cup (98.6%) was similar to survivorship for all cementless cup revisions in the NJR database (98.5%), as seen in Figure 2. When the cup alone was revised, six-year survivorship of the subject cup (98.6%) and all NJR cementless cups (98.5%) was also similar. However, the subject cup survivorship remained at 98.6% from 4 to 6 years post-implantation, while survivorship for all cementless cups decreased slightly from years 4 to 6. The similarities between the revision risk of the subject system and all cementless cups in the NJR can be seen in the Cox Proportional Hazards model for revision risk ratios provided in Figure 3. Patients with the subject cup implanted for an average of 5.88 years reported Oxford Hip, EQ-5D, and EQ VAS scores of 39.60 ± 10.78, 0.801 ± 0.259, and 75.49 ± 19.25, respectively. Conclusions. The subject acetabular cup with a ceramic on ceramic articulation exhibited similar survivorship to all other cementless acetabular cups, excluding those with metal on metal bearings, in the NJR. Patients implanted with the subject system for an average of 5.88 years reported what are considered satisfactory Oxford Hip, EQ-5D, and EQ VAS scores. This survivorship and PROMs data is the first report of mid-term outcomes with the subject components

Introduction. The bearing surfaces of ceramic-on-ceramic (CoC) total hip replacements (THR) show a substantially lower wear rate than metal-on-polyethylene (MoP) THR in-vitro. However, revision rates for CoC THR are comparable with MoP. Our hypothesis that an explanation could be adverse reaction to metal debris (ARMD) from the trunnion led us to investigate the wear at both the bearing surfaces and the taper-trunnion interface of a contemporary CoC THR in an in-vitro study. Methods. Three 36mm CoC hips were tested in a hip simulator for 5 million cycles (Mc). BIOLOX. ®. delta ceramic femoral heads were mounted on 12/14 titanium (Ti6Al4V) trunnions. Wear of femoral heads, acetabular liners and trunnions was determined gravimetrically using the analytical balance. Roughness measurements (Sa) were taken on the articulating surfaces (pre and post-test) and on the trunnion surfaces (worn and unworn). Furthermore, Energy Dispersive X-ray Spectroscopy (EDX) was used to identify and quantify the wear debris present in the lubricant using scanning electron microscope (SEM). Results and Discussion. The total volumetric wear was 0.25 mm. 3. for CoC joints and 0.29 mm. 3. for titanium trunnions. The total wear volume of the titanium trunnions was in agreement with an explant study (Kocagoz et al, 2016, CORR) which quantified the volumetric material loss from retrieved trunnions with the total wear ranging from 0.0–0.74 mm. 3. The Sa values, pre-and post-test, for heads were 0.003 ± 0.002 and 0.004 ± 0.001 µm and for liners were 0.005 ± 0.001 and 0.005 ± 0.001 µm. Pre-and post-test measurements for Sa of heads (p = 0.184) and liners (p = 0.184) did not show a statistically significant change. The Sa of the trunnions on the unworn and worn areas showed a statistically significant decrease from 0.558 ± 0.060 to 0.312 ± 0.028 µm respectively (p < 0.001). Analysis of wear debris within the lubricant confirmed the presence of titanium. A recent clinical study (Matharu et al, 2016, BMC Musc Dis) found more ARMD in CoC hips than MoP hips. This is despite there being fewer metallic components in a CoC hip than a MoP hip. This in vitro study has shown that one source of metal debris in a CoC hip is the taper-trunnion junction. Conclusion. An explanation for wear related failures in ceramic-on-ceramic hip arthroplasty, despite the low wear arising at the articulating surfaces, may now exist; namely that titanium wear particles are generated from the trunnion. No other long-term hip simulator studies have measured wear at the taper-trunnion junction

Introduction. Wear performances and fracture toughness of the alumina-matrix composite (AMC) Biolox-delta(r) are pointed out in the literature. This study is a prospective monocentric evaluation of 32 and 36 mm AMC/AMC bearing surfaces. Material and methods. 141 THA were included prospectively since 2006 in 127 patients. (62 females, 65 males, mean age 62, 2 years, mean BMI 25, 5). 134 cases were primary implantations. Mean follow-up is 40.9 months (29.8-53.4). In all patients we used the same cementless stem and cup. Clinical and radiological data were evaluated with a special attention for ceramic fracture and squeaking. Results. At follow-up mean HHS is 95.4. We faced current problems in this series (2 post-op.dislocations in non compliant patients, 1 hematoma, 3 early septic complications in immunodepressed patients). Intraoperative events were 3 non relevant femur fractures and 1 partial acetabular fracture. 4 cases needed a revision (1 cup and 1 stem loosening, 1 painful stem, 1 limb length discrepancy). No abnormal wear, osteolysis or implants migration could be detected in the other cases. No ceramic head fracture or liner chipping occurred. No patient reported squeaking. Discussion and conclusion. In this monocentric report the Delta COC articulation provides similar functional scores and survivorship as previously published ceramic on ceramic series. We did not observe ceramic fracture. Unusual rates of liner chipping have been described in an other multicentric study. According to our experience and despite the short follow-up, we suggest that those complications could be related to cup design rather than to the ceramic material

Introduction

The utilization of ceramic components in Total Hip Arthroplasty has experienced an expanded acceptance by the orthopedic community. This increased acceptance has been largely due to the lower risk of fracture due to the introduction of zirconia toughened alumina ceramics. This extra-high strength ceramic composite has been proven clinically over the past 13 years and found to be much more reliable than previous ceramic materials. The goal is to verify this finding by published registry data as well as clinical outcome.

Introduction

There is interest in minimally invasive solutions that reduce osteoarthritic symptoms and restore joint mobility in the early stages of cartilage degeneration or damage. The aim of the present study was to evaluate the Biolox®delta alumina-zirconia composite as a counterface for articulation against live cartilage in comparison to the clinically relevant CoCrMo alloy using a highly controlled in vitro ball-on-flat articulation bioreactor that has been shown to rank materials in accord with clinical experience.

Polyimide (MP-1, MMATech, Haifa, Israel), is a high performance aerospace thermoplastic used for its lubricity, stability, inertness and radiation resistance. A wear resistant thin robust bearing is needed for total hip arthroplasty (THR). After independent laboratory testing, in 2006, the author used the material as a bearing in two Reflection (Smith and Nephew, USA) hip surgeries. The first, a revision for polyethylene wear, survives with no evidence of wear, noise, new osteolysis or complications related to the MP-1 bearing after 16 yrs. The second donated his asymptomatic MP-1 hip at 6.5yrs for post-mortem examination. There were no osteoclasts, cellular reaction bland in contrast to that of polyethylene. In 2013 a clinical study with ethical committee approval was started using a Biolox Delta (Ceramtec, Germany) head against a polyimide liner in 97 patients. MMATech sold all liners, irradiated: steam 52:45. Sixteen were re-machined in New Zealand. Acetabular shells were Delta PF (LIMA, Italy). The liner locked by taper. The cohort consisted of 46:51 M:F, and ages 43 to 85, mean 65. Ten received cemented stems. For contralateral surgery, a ceramic or polyethylene liner was used. Initial patients were lower demand, later, more active patients, mountain-biking and running. All patients have on-going follow up, including MP-1 liner revision cases. There has been no measurable wear, or osteolysis around the acetabular components using weight-bearing radiographs. Squeaking within the first 6 weeks was noted in 39 number of cases and subtle increase in palpable friction, (passive rotation at 50 degrees flexion), but then disappeared. There were 6 revisions, four of which were related to cementless Stemsys implants (Evolutis, Italy) fixed distally with proximal linear lucencies in Gruen zones 1 and 7, and 2 and 6. No shells were revised and MP-1 liners were routinely changed to ceramic or polyethylene. The liners showed no head contact at the apex, with highly polished contact areas. There were no deep or superficial infections, but one traumatic anterior dislocation at 7 years associated with 5 mm subsidence of a non-collared stem. The initial squeaking and increased friction was due to the engineering of the liner / shell composite as implanted, not allowing adequate clearance for fluid film lubrication and contributed to by shell distortion during impaction. The revised bearings were “equatorial” rather than polar, and with lack of wear or creep this never fully resolved. Where the clearance was better, function was normal. The “slow” utilization was due to my ongoing concern with clearances not being correct. The revision of 4 Stemsys stems, tribology issues may have contributed, but non “MP-1” / Stemsys combinations outside this study have shown the same response, thought to be due to de-bonding of the hydroxyapatite coating. With correct engineering and clearances, a 3.6 mm thick MP-1 bearing, a surface Ra<0.5, steam sterilized, shows no appreciable wear, and with confidence, can be used as a high performance THR bearing

The second wave of COVID-19 infections in 2021 resulting from the delta strain had a significantly larger impact on the state of New South Wales, Australia and with it the government implemented harsher restrictions. This retrospective cohort study aims to explore how the increased restrictions affected hand trauma presentations and their treatment. Retrospective analysis was performed on patients who underwent hand surgery from the period of June 23 – August 31 in 2020 and 2021 at a level one trauma centre in Western Sydney. During the second-wave lockdown there was an 18.9% decrease in all hand trauma presentations. Despite widespread restrictions placed on the manufacturing, wholesale, retail and construction industries, there was an insignificant difference in work injuries. Stay-at-home orders and reduced availability of professional tradespersons likely contributed to an increase in DIY injuries. Significant reductions in metacarpal and phalangeal fractures coincided with significantly curtailed sporting seasons. The findings from this study can assist in predicting the case-mix of hand trauma presentations and resource allocation in the setting of future waves of COVID-19 and other infectious diseases

Background. In recent years, ‘Get It Right First Time (GIRFT)’ have advocated cemented replacements in femoral part of Total hip arthroplasty (THA) especially in older patients. However, many studies were unable to show any difference in outcomes and although cemented prostheses may be associated with better short-term pain outcomes there is no clear advantage in the longer term. It is not clear when and why to do cemented instead of cementless. Aim. To assess differences in patient reported outcomes in uncemented THAs based on patient demographics in order to decide when cementless THA can be done safely. Method. Prospective data collection of consecutive 1079 uncemented THAs performed for 954 patients in single trust between 2010 and 2020. Oxford Hip Score (OHS) and complications were analysed against demographic variables (age, sex, BMI, ASA) and prosthesis features (femoral and acetabular size, offset and acetabular screws). Results. The mean pre-operative OHS was 14.6 which improved to 39.0 at 1 year follow up (P Value=0.000). There was no statistically significant difference between OHS outcome in patients aged over 70 versus younger groups. With a small number of revisable complications increase with age from 50s upwards. Male patients’ OHS score was on average 2.4 points higher than women. Men, however were 2.9 times more likely to experience fractures and high offset hips were 2.5 times more likely to experience dislocations. DAIR, intraoperative calcar fractures, post-operative fractures and dislocations were not associated with worse OHS. Patients with increased BMI had worse pre and post-operative hip functions yet, there was a significant multivariate association between increased BMI and increased improvement in OHS from pre-op to 1 year in women aged 55–80 and men under the age of 60. Femoral stem size increases with age but decreases in male patients over 80. There was no difference found in OHS between bilateral hip replacements and unilateral, nor was there any change found with laterality side of the replacement. Conclusions. This study suggests that ageing >70 is not associated with poorer outcomes despite small number of revisable complication rates that increase with age from 50 upwards. Men had marginally higher average OHS than women At 1 year. Higher BMI or ASA scores are associated with worse pre-operative hips and worse final outcome score. Despite this, the Delta OHS increases with increased BMI shown in the 55–80 year old female patients and male patients under 60. Key Words: THR, Uncemented, Oxford hip score, outcome

INTRODUCTION. Ceramic-on-ceramic hip resurfacing offers a bone conserving treatment for more active patients without the potential metal ion risks associated with resurfacing devices. The Biolox Delta ceramic material has over 15 years of clinical history with low wear and good biocompatibility but has been limited previously in total hip replacement to 48mm diameter bearings [1]. Further increasing the diameter for resurfacing bearings and removing the metal shell to allow for direct fixation of the ceramic cup may increase the wear of this material and increase the risk of fracture. METHODS. Eighteen implants (ReCerf™, MatOrtho, UK; Figure1) were wear tested; six were ⊘40mm (small) and twelve ⊘64mm (large). All small and six large implants were tested under ISO 14242 standard conditions for 5 million cycles (mc) at 30° inclination (45° clinically). The six remaining large implants were tested under microseparation conditions in which rim contact was initiated during heel strike of the gait cycle for 5mc. Cups were orientated at 45° inclination (60° clinically) to allow for separation of the head and cup with a reduced 50N swing phase load and a spring load applied to induce a 0.5mm medial-superior translation of the cup. Wear was determined gravimetrically at 0.5mc, 1mc and every mc after. RESULTS. Wear was low in both standard and microseparation tests, less than 1mm. 3. cumulatively over 5mc (Figure 2). Standard conditions showed a run-in wear phase over the first mc followed by negligible wear in both diameters. The run-in wear significantly increased from 0.2mm. 3. /mc in the 40mm diameter bearings to 0.5mm. 3. /mc with the larger diameter implants. Under microseparation conditions, there was low wear over the first mc, increasing to 0.28mm. 3. /mc between 1–3mc. The wear rate reduced to 0.11mm. 3. /mc from 3=5mc. Stripe wear was evidenced on the microseparated components. There were no incidences of fracture or squeaking. DISCUSSION. Biolox Delta is known for its low wear rates but published results have only reported testing up to ⊘36mm [2]. Increasing the diameter to 64mm showed increased wear compared to smaller diameters but this was only significant over the first mc suggesting similar performance long term. Microseparation testing of these large sized bearings doubled the cumulative wear produced over 5mc but wear measured was still much lower than other bearing combinations. Wear of metal-on-metal resurfacing implants under these high angle, microseparation conditions has been reported up to 10.5mm. 3. /mc [3], significantly higher than any wear rate reported in the current study. Despite the 3mm wall thickness, no fracture of the cup occurred but stripe wear was observed in the ceramic components. SIGNIFICANCE. Biolox Delta ceramic is appropriate for use in larger diameters without excessive wear or damage to the bearings. The improved biocompatibility of the material may allow for hip resurfacing to be offered to more patients than currently available. For any figures or tables, please contact the authors directly

INTRODUCTION. Ligament balancing aims to equalize lateral and medial gaps or tensions for optimal functional outcomes. Balancing can now be measured as lateral and medial contact forces during flexion (Roche 2014). Several studies found improved functional outcomes with balancing (Unitt 2008; Gustke 2014a; Gustke 2014b) although another study found only weak correlations (Meneghini 2016). Questions remain on study design, optimal lateral-medial force ratio, and remodeling over time. Our goals were to determine the functional outcomes between pre-op and 6 months post-op, and determine if there was a range of balancing parameters which gave the highest scores. METHODS. This IRB study involved a single surgeon and the same CR implant (Triathlon). Fifty patients were enrolled age 50–90 years. A navigation system was used for alignments. Balancing aimed for equal lateral and medial contact forces throughout flexion, using various soft tissue releases (Meneghini 2013; Mihalko 2015). The patients completed a Knee Society evaluation pre-op, 4 weeks, 3 months and 6 months. The total (medial+lateral) force, and the medial/(medial+lateral) force ratio was calculated for 4 flexion angles and averaged. These were plotted against Pain, Satisfaction, Delta Function (postop – preop), and Delta Flexion Angle. The data was divided into 2 groups. 1. By balancing parameters. T-Test for differences in outcomes between the 2 groups. 2. By outcome parameters. T-Test for differences in Balancing Parameters between the two groups. RESULTS. Ranges were: Balancing Parameters; Total Force 19–70 lbs; the Force Ratio 0.34 to 0.75. Outcome Measures; Pain 11–25, Satisfaction 15–40, Delta Function −20–70, Delta Flexion −3–29. The only significance was that higher Delta Flexion was associated with a higher Force Ratio. An unpaired t-test was carried out for cases with a balancing ratio between 0.48–0.68 versus cases outside that band (Fig 1). The mean gains were 27.2+/−20 versus 18.8+/−18.5. However the difference at p=0.104 was not significant, due to the large standard deviation. An odds ratio calculation was carried out for the above range, and 35 points Delta Function (Figure 2). The range of 0.48–0.68 and a gain of 35 was determined by optimizing. For patients in the balancing range, 39% achieved that; for patients outside the range, only 8% (Figure 2). This gave an odds ratio of 4.9 that within the balancing range 0.45–0.68, there would be a functional gain of 35 points or more. DISCUSSION. A striking characteristic of the data was the wide range of the functional scores and the narrow band of balancing parameters. This explained the lack of significance between the sets of 2 groups, which might have demonstrated an association of higher scores with high or low balancing values or ranges. However by reverting to an odds ratio analysis, in this case for gain in functional score, there was a suggestion that a certain balancing range provided the best functional results. This suggests that the best average balancing target for surgery is around 0.58 (higher medial force than lateral) rather than 0.5. However further studies and longer follow-up will be needed to verify this. For any figures or tables, please contact authors directly (see Info & Metrics tab above).

Introduction. Hip replacements are falling short of matching the life expectancy of coxarthritis patients, due to implanting THR in younger patients and due to increasingly active patients. The most frequently implanted hip prostheses use cross linked (XL) polyethylene (PE) on metal bearings in the USA and most of the Western world. Concerns remain in the long term around the potential of wear debris-induced aseptic loosening. Thus exploring lower-wearing alternative bearings remains a major research goal. PEEK (poly-ether-ether-ketone) is a thermoplastic polymer with enhanced mechanical properties. This study compared the wear of PEEK to the wear of cross linked polyethylene, when sliding against cobalt chrome (CoCr) metallic counterfaces, and compared the wear of carbon-fibre reinforced (CFR)-PEEK to cross linked polyethylene when sliding against metallic and ceramic counterfaces under different contact stresses within the hip joint. Methods. The following materials were studied: unfilled PEEK (OPTIMA, Invibio) and CFR-PEEK (MOTIS, Invibio) against either high carbon (HC) CoCr or Biolox Delta ceramic plates. The comparative control material was a moderately cross-linked PE (Marathon, DePuy Synthes). A simple geometry wear study was undertaken. A rotational motion of ±30° across a sliding distance of ±28 mm (cross shear of 0.087), and contact pressures of 1.6 or 4 MPa were applied. The lubricant was 25% (v/v) bovine serum and the wear test was conducted for 1 million cycles at 1 Hz. Wear was assessed gravimetrically. A validated soak control method was used to adjust for serum absorption-induced mass changes during the wear test. Surface profilometry was assessed pre and post wear test. Results. Unfilled PEEK produced a six-fold higher wear factor than XL PE against HC Co Cr (p value <0.0001). CFR-PEEK vs. Biolox Delta produced a two-fold lower wear factor than XL PEvs. HC Co Cr (p value = 0.003). CFR-PEEK vs. Biolox Delta had the lowest wear factor among all studied combinations. The wear of CFR-PEEK vs. HC CoCr was higher than XL PEvs. HC CoCr (Figure 1). The counterface surfaces were scratched when articulating against CFR-PEEK. This was more evident on CoCr plates, with the average surface roughness increasing from 0.005 µm to 0.32 µm (p value = 0.0048). This might explain the accelerated wear in the CFR-PEEK vs. HC CoCr combinations. Higher contact pressures led to a 30 % reduction in the wear factor of CFR-PEEK vs. Biolox Delta combination (p value = 0.048), while no significant impact was noted against HC CoCr (Figure 2). Conclusions. The injection moulded carbon fibre reinforced PEEK vs. Biolox Delta ceramic generated significantly lower wear compared with XL PE (even under higher contact pressures). CFR-PEEK vs. Biolox Delta may lead to longer lasting hip replacements, and will be the subject of further investigations

Introduction. Two types of ceramic materials currently used in total hip replacements are third generation hot isostatic pressed (HIPed) alumina ceramic (commercially known as BIOLOX®forte, CeramTec) and fourth generation alumina matrix composite ceramic consisting of 75% alumina, 24% zirconia, and 1% mixed oxides (BIOLOX®delta, CeramTec). Delta ceramic hip components are being used worldwide, but very few studies have analyzed retrieved delta bearings. The aim of this study is to compare edge loading ‘stripe’ wear on retrieved femoral heads from delta-on-delta, delta-on-forte and forte-on-forte ceramic bearings revised within 2 years in vivo. Material and Methods. Ceramic bearings revised at one center from 1998 to 2010 were collected (61 bearings). Eleven delta heads revised between 1–33 months were compared to 24 forte femoral heads with less than 24 months in vivo (Figure 1). The surface topography of the femoral heads was measured using a RedLux AHP (Artificial Hip Profiler, RedLux Ltd, Southampton, UK). Three representative samples were examined with a FEI Quanta 200 Scanning Electron Microscope (SEM). Results. The median time to revision for delta femoral heads was 12 months, compared to 13 months for forte femoral heads. Sixteen out of 20 forte femoral heads and 6 out of 11 delta femoral heads had edge loading wear (Figure 2). The average volumetric wear rate for forte was 0.96 mm. 3. /yr (median 0.13 mm. 3. /yr), and 0.06 mm. 3. /yr (median 0.01 mm. 3. /yr) for delta (p=0.03). There was no significant difference (p>0.05) in age, gender, time to revision or femoral head diameter between the two groups. Conclusions. Edge loading wear occurs in BIOLOX®delta ceramic bearings. Edge loading wear volumes and wear rates are less in these bearings compared to BIOLOX®forte bearings. These findings are consistent with hip simulator studies. Early analysis of retrieved implants is important to check the in vivo performance of biomaterials

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

Managing severe acetabular bone defects during primary and revision total hip arthroplasty is a challenging problem. Standard treatment options for this cases is using of acetabular reconstruction type-Burch-Schneider rings. Unfortunately, the possibility of osseointegration of these implants with surrounding bone has always remained a contentious issue. The emergence in recent years of new designs of trabecular titanium, representing a symbiosis of acetabular reconstructive plates and modular cup helped to solve this problem on a completely new level. The aim of this prospective study is to evaluate the short and mid-term clinical and radiographic outcomes of different types of acetabular revision cups - old and new design. From 2006 to 2015, we performed 48 acetabular reconstruction with reconstruction rings CONTUR Smith and Nephew(group 1) and 34 operations with Delta TT Lima Revision system (group 2). The mean age of patients was 59.2 years (range 30–79). Indications for operations included fractures in acetabular region (10 pat – 12,2 %), acetabular nonunions with bone defects (14 pat – 17,1%), aseptic loosening with multiple dislocation of the primary implants in 38 cases (46,3%) and second stage of infection treatment in 20 cases (24.4%). Clinical and functional outcomes were evaluated by Harris Hip Score (HHS). Bone density in Charnley's zones was measured by dual-energy x-ray absorptiometry. With CONTUR reconstruction rings were used 3 different types of bearing surface articulation (22 metal/polyethylene, 10 ceramic/polyethylene, and 16 oxinium/polyethylenel). With Delta TT Revision system were used metal/poly couples in 22 cases, ceramic/poly in 6 cases, and ceramic/ceramic couple in 4 cases. In two patients with high risk of dislocations were used double mobility system. In all operations with CONTUR rings was used bone impaction grafting to fill cavitary defects (Paprosky 2B-3A), with Delta TT Revision system in 14 cases (41,2%) additionally TT augments were used. In group 1 were 3 dislocations (6,3 %), 2 deep infections (4,2 %) and 4 aceptic loosenings with secondary instability of implants (8,3 %). In group 2 Trabecular Titanium showed a high capacity of osseointegration, providing good results in short-term follow-up. We registered only 2 dislocations (5,8 %) and 1 aceptic loosening (2,9 %). The mean HHS increased from 39.7 (range 23–62) preoperatively to 86.5 (range 68–98) at the last follow-up examination. The implanted cups were radiographically stable at the last follow-up visit (1 and 2 years) without radiolucent lines or periprosthetic osteolysis. Conclusions. Delta Revision TT is a good solution for acetabular reconstruction even when there are cavitary and segmental bone defects. Modularity of this system make it possible to correct inlay position, center of hip rotation and minimising the risk of dislocation

Introduction. Lipped liners have the potential to decrease the rate of revision for instability after total hip replacement since they increase the jumping distance in the direction of the lip. However, the elevated lip also may reduce the Range of Motion and may lead to early impingement of the femoral stem on the liner. It is unclear whether the use of a lipped liner has an impact on the level of lever-out moments or the contact stresses. Therefore, the aim of the current study was to calculate these values for lipped liners and compare these results to a conventional liner geometry. Materials and Methods. 3D Finite Element studies were conducted comparing a ceramic lipped liner prototype and a ceramic conventional liner both made from BIOLOX. ®. delta. The bearing diameter was 36 mm. To apply loading, a test taper made of titanium alloy was bonded to a femoral head, also made from BIOLOX. ®. delta. Titanium was modeled with a bilinear isotropic hardening law. For the bearing contact a coefficient of friction of both 0.09 or 0.3 was assumed to model a well and poorly lubricated system. Frictionless contact was modeled between taper and liner. Pre-load was varied between 500 N and 1500 N and applied along the taper axis. While keeping pre-load constant, lever-out force was applied perpendicular to the taper axis until subluxation occurred. Liners were fixed at the taper region. Lever-out moment, equivalent plastic strain and von Mises stress of the taper, bearing contact area and contact area between taper and liner was evaluated. Results. With increasing pre-load, larger lever-out moment, equivalent plastic strain, contact area between taper and liner and bearing contact area was found for both liner designs. However, von Mises stresses were nearly constant but slightly exceeded yield strength of titanium. For all evaluated parameters almost no differences were found between the liner designs. Lever-out moments were comparable for both designs ranging from 4.5–10.5 Nm for the lipped liner and 4.4–10.2 Nm for the conventional liner. The increase of the coefficient of friction strongly affected lever-out moments, equivalent plastic strain and contact area between taper and liner. The other parameters were not affected by varying the coefficient of friction. Discussion. This study did not find significant differences in the lever-out behavior of the lipped acetabular liner compared to the conventional liner design. The inner geometry of the lipped liner is comparable to the conventional liner inner geometry. Therefore, contact area showed no significant differences and contact mechanics are identical in the current setup leading to similar results of both liner designs. For both designs small plastic deformations in the contact point of the taper were found at the contact region between liner and taper. However, the investigated mechanical parameters did not differ between the two investigated liner types. For any figures or tables, please contact authors directly

Introduction. Metal-on-metal bearings (MoM) have been reported to release metal ions that are potentially leading to adverse tissue reactions. Alternatively, ceramic-on-ceramic bearings (CoC) are an attractive treatment for young and active patients and composite materials like zirconia toughened alumina (ZTA) have been successfully introduced clinically. One of the most common ZTA-material in CoC is the Biolox® delta, manufactured by Ceramtec. Along with alumina and zirconia, this material also contains traces of chromium, strontium and yttrium. The aim of this study was to analyse the ion release for these materials clinically as well as experimentally. Material and Methods. Within a clinical trial, three different patient groups were compared: a) a control group without any implants, b) patients, three months after unilateral treatment with Biolox® delta CoC and c) patients, twelve months after unilateral treatment with Biolox® delta CoC. Whole-blood samples were collected and analysed in regards to the trace elements using high-resolution-ICP-MS. In the experimental setup, the leaching behaviour of five Biolox® delta ceramic heads and five CoCr-heads was analysed. The heads were immersed in serum for seven days at 37°C. The ion-release of aluminium, zirconium, cobalt, chromium, strontium and yttrium were detected based on high-resolution-ICP-MS. Results. In the patient groups, most elements remained below their specific limit of detection (LoD), except for aluminium and strontium. For aluminium, the values of the control and the twelve- month group were below the LoD (27.2µg/L) and the three month values were only slightly increased (median: 34.2µg/L). For strontium median values of 39.7µg/L were found in the control group which were higher after three month (79.6µg/L) and returned to 41.1 µg/L after twelve months. However, this difference was not statistically significant. The leaching experiments showed that high amounts of cobalt (177.3µg/L) and chromium (4.2µg/L) were released from the metallic heads, which was not seen in the ceramic material. Similar to the patient control group, a seemingly high background-concentration of strontium was found in the serum (98.3µg/L) which was only slightly increased by the ceramic material (107.7µg/L). Discussion and Conclusion. The current study revealed that there was no significant increase of any analysed material or trace elements in the target patients treated with CoC bearings. The clinical trial also showed that strontium is a trace element that exists in the human body regardless of the presence or absence of an implant. However, with MoM high values of cobalt were released. As this release occurred even without any joint articulation, as shown in the experiments, surface corrosion seems to be a relevant mechanism in the ion release of MoM. A limitation of the study is that different patient groups were compared within the clinical trial