Objectives. The biomembrane (induced membrane) formed around polymethylmethacrylate (PMMA) spacers has value in clinical applications for bone defect reconstruction. Few studies have evaluated its cellular, molecular or stem cell features. Our objective was to characterise induced membrane morphology, molecular features and osteogenic stem cell characteristics. Methods. Following Institutional Review Board approval, biomembrane specimens were obtained from 12 patient surgeries for management of segmental bony defects (mean patient age 40.7 years, standard deviation 14.4). Biomembranes from nine tibias and three femurs were processed for morphologic, molecular or stem cell analyses. Gene expression was determined using the Affymetrix GeneChip Operating Software (GCOS). Molecular analyses compared biomembrane gene expression patterns with a mineralising osteoblast culture, and gene expression in specimens with longer spacer duration (> 12 weeks) with specimens with shorter durations. Statistical analyses used the unpaired student t-test (two tailed; p < 0.05 was considered significant). Results. Average PMMA spacer in vivo time was 11.9 weeks (six to 18). Trabecular bone was present in 33.3% of the biomembrane specimens; bone presence did not correlate with spacer duration. Biomembrane morphology showed high vascularity and collagen content and positive staining for the key bone forming regulators, bone morphogenetic protein 2 (BMP2) and runt-related transcription factor 2 (RUNX2). Positive differentiation of cultured biomembrane cells for osteogenesis was found in cells from patients with PMMA present for six to 17 weeks. Stem cell differentiation showed greater variability in pluripotency for osteogenic potential (70.0%) compared with chondrogenic or adipogenic potentials (100% and 90.0%, respectively). Significant upregulation of BMP2 and 6, numerous collagens, and bone gla protein was present in biomembrane compared with the cultured cell line. Biomembranes with longer resident PMMA spacer duration (vs those with shorter residence) showed significant upregulation of bone-related, stem cell, and vascular-related genes. Conclusion. The biomembrane technique is gaining favour in the management of complicated bone defects. Novel data on biological mechanisms provide improved understanding of the biomembrane’s osteogenic potential and molecular properties. Cite this article: Dr H. E. Gruber. Osteogenic, stem cell and molecular characterisation of the human induced membrane from extremity bone defects. Bone Joint Res 2016;5:106–115. DOI: 10.1302/2046-3758.54.2000483

Prosthetic joint infection is one of the most challenging complications of joint alloplasty and the diagnosis remains difficult. The aim of the study was to investigate the bacterial flora in surgical samples from 22 prosthetic patients using a panel of culture-independent molecular methods including broad range 16S rRNA gene PCR, cloning, sequencing, phylogeny, quantitative PCR (qPCR), and fluorescence in situ hybridization (FISH). Concomitant samples were cultured by standard methods. Molecular methods detected presence of bacteria in samples from 12 of 22 patients. Using clone libraries a total of 40 different bacterial species were identified including known pathogens and species not previously described in association with prosthetic joint infections. The predominant species were Propionibacterium acnes and Staphylococcus epidermidis; polymicrobial infections were found in 9 patients. Culture-based methods showed bacterial growth in 8 cases with the predominant species being S. epidermidis. Neither anaerobic bacteria (including P. acnes) nor any of the species not previously described in implant infections were isolated. Additionally, 7 of the 8 culture positive cases were monomicrobial. Overall, the results of culture-based and molecular methods showed concordance in 11 cases (hereof 9 negative by both methods) and discrepancy in 6 cases. In the remaining 5 cases, culture-based methods identified only one species or a group of bacteria (e.g., coagulase negative staphylococci or coryneform rods), while culture-independent molecular methods were able to detect several distinct bacterial species including a species within the group identified by culture. A qPCR assay was developed to assess the abundance of Propionibacterium while S. aureus was quantified by a published S. aureus qPCR assay. These quantifications confirmed the findings from the clone library approach and showed the potential of qPCR for fast detection of bacteria in orthopedic samples. Additionally, both single cells and microcolonies were visualized using FISH and confocal scanning laser microscopy. In conclusion, the molecular methods detected a more diverse bacterial flora in prosthetic joint infections than revealed by standard culture-based methods, and polymicrobial infections were more frequently observed. The pathogenesis of these microorganisms and their role in implant-associated infections needs to be determined

Improving periprosthetic bone is essential for implant fixation and reducing peri-implant fracture risk. This studied examined the individual and combined effects of iPTH and mechanical loading at the cellular, molecular, and tissue level for periprosthetic cancellous bone. Adult rabbits had a porous titanium implant inserted bilaterally on the cancellous bone beneath a mechanical loading device on the distal lateral femur. The right femur was loaded daily, the left femur received a sham loading device, and half of the rabbits received daily PTH. Periprosthetic bone was processed up to 28 days for qPCR, histology, and uCT analysis. We observed an increase in cellular and molecular markers of osteoblast activity and decrease in adipocytic markers for both treatments, with small additional effects in the combined group. Loading and iPTH led to a decrease and increase, respectively, in osteoclast number, acting through changes in RANKL/OPG expression. Changes in SOST and beta-catenin mRNA levels suggested an integral role for the Wnt pathway. We observed strong singular effects on BV/TV of both loading (1.53 fold) and iPTH (1.54 fold). Combined treatment showed a small additive effect on bone volume. In conclusion, loading and iPTH act through a pro-osteoblastic/anti-adipocytic response and through control of bone turnover via changes in the RANKL/OPG pathway. These changes led to a small additional, but not synergistic, increase in bone volume with the combined therapy

Introduction. Microbiological diagnosis of bone and joint infections (BJIs) currently relies on standard cultures which are time consuming and lack sensitivity. Various molecular approaches have been described and allowed improvement of BJI diagnosis. This study evaluated for the first time the performance of a DNA microarray-based assay (Prove-it™ Sepsis assay, PISA) for the rapid (<6 hours) detection and identification of 50 different species involved in BJI directly from clinical samples. Material and methods. We retrospectively selected 130 bone and joint samples (67 synovial fluids and 63 bone biopsies) including 114 positive and 16 negative samples. The microbiological diagnosis had been previously established either by culture(C+, n=53) or by PCR16S and sequencing when culture was negative (C-/PCR+). The positive samples were selected to match the species targeted on the DNA microarray. DNA extraction was performed before proceeding to PISA amplification and hybridization on every selected sample. Results. Among the 16 negative samples, one was detected positive with S. epidermidis by PISA, result that was secondarily confirmed using specific PCR. Among the 114 positive samples, 62.3% were positive using PISA with highly concordant identification compared to culture and PCR16S/sequencing results. Forty-three samples (37.7%) remained negative, illustrating a defect of sensitivity. However, PISA accurately detected methicillin resistance not only among the 16 C+/PISA+ Staphylococcus species (n=5) but also among the 28 C-/PCR16S+ Staphylococcus species (n=12) offering crucial rapid information to adapt the treatment of staphylococcal BJIs. Seven polymicrobial samples were also identified without extensive experiments. Discussion – Conclusion. Even if the sensitivity deserves to be improved by optimizing DNA extraction and investigating on human DNA interference, these preliminary promising results highlight that this new and simple microarray method could be in the future an alternative to conventional PCR16S for the diagnosis of BJI

The incidence of deep-vein thrombosis and the need for thromboprophylaxis following isolated trauma below the knee is uncertain. We have investigated this with a prospective randomised double-blind controlled trial using low molecular weight heparin with saline injection as placebo in patients aged between 18 and 75 years who had sustained an isolated fracture below the knee which required operative fixation. All patients had surgery within 48 hours of injury and were randomised to receive either the placebo or low molecular weight heparin for 14 days, after which they underwent bilateral lower limb venography, interpreted by three independent radiologists. Further follow-up was undertaken at two, six, eight and 12 weeks. A total of 238 patients fulfilled all the inclusion criteria, with 127 in the low molecular weight heparin group and 111 in the placebo group, all of whom underwent bilateral venography. There was no statistically significant difference in the incidence of deep-vein thrombosis between those patients treated with low molecular weight heparin or the placebo (p = 0.22). The number of deep-vein thromboses in the two groups was 11 (8.7%) and 14 (12.6%), respectively. Age and the type of fracture were significantly associated with the rate of deep-vein thrombosis (p = 0.001 and p = 0.009, respectively) but gender, comorbidities and the body mass index were not. The overall incidence of deep-vein thrombosis in this series was 11%. There was no clinical or statistical significant reduction in the incidence of deep-vein thrombosis with the use of thromboprophylaxis. However, we accept that owing to a cessation of funding, recruitment to this trial had to be ended prior to establishing the necessary sample size. Our results cannot, therefore, categorically exclude the possibility that low molecular weight heparin treatment could be beneficial. We recommend a further multicentre trial be undertaken to resolve this matter

MicroRNAs (miRNAs ) are small non-coding RNAs that regulate gene expression. We hypothesised that the functions of certain miRNAs and changes to their patterns of expression may be crucial in the pathogenesis of nonunion. Healing fractures and atrophic nonunions produced by periosteal cauterisation were created in the femora of 94 rats, with 1:1 group allocation. At post-fracture days three, seven, ten, 14, 21 and 28, miRNAs were extracted from the newly generated tissue at the fracture site. Microarray and real-time polymerase chain reaction (PCR) analyses of day 14 samples revealed that five miRNAs, miR-31a-3p, miR-31a-5p, miR-146a-5p, miR-146b-5p and miR-223-3p, were highly upregulated in nonunion. Real-time PCR analysis further revealed that, in nonunion, the expression levels of all five of these miRNAs peaked on day 14 and declined thereafter. . Our results suggest that miR-31a-3p, miR-31a-5p, miR-146a-5p, miR-146b-5p and miR-223-3p may play an important role in the development of nonunion. These findings add to the understanding of the molecular mechanism for nonunion formation and may lead to the development of novel therapeutic strategies for its treatment. Cite this article: Bone Joint J 2015; 97-B:1144–51

Nasal carriers of methicillin sensitive Staphylococcus aureus (MSSA) have an increased risk for health-care associated infections. There is currently no national screening policy for the detection of MSSA in the UK. This study aimed to: evaluate the diagnostic performance of molecular and culture techniques in MSSA screening, determine the cause of any discrepancy between the diagnostic techniques, and model the potential effect of different diagnostic techniques on MSSA detection in orthopaedic patients. Paired nasal swabs for PCR assay and culture of S. aureus were collected from a study population of 273 orthopaedic outpatients due to undergo joint replacement surgery. The prevalence of MSSA nasal colonisation was found to be between 22.4–35.6%. The current standard direct culturing methods for detecting S. aureus significantly underestimated the prevalence (p=0.005), failing to identify its presence in ∼1/3 of patients undergoing joint replacement surgery. Modelling these results to national surveillance data, it was estimated that 800–1200 MSSA surgical site infections could be prevented annually in the UK by using alternative diagnostic methods to direct culture in pre-operative MSSA screening and eradication programmes

Scar tissue formation secondary to acute muscle injury, surgical wounding and compartment syndrome can result in significant functional impairment and predispose to further injury. The source of fibroblasts, and the molecular mechanisms driving their activation and persistence in skeletal muscle fibrosis are not known. We hypothesized that cells expressing PDGFRβ become fibroblasts in response to injury and that targeting αv integrins in these cells reduces skeletal muscle fibrosis. We used double-fluorescent reporter mice to demonstrate that cells expressing PDGFRβ become activated myofibroblasts in response to cardiotoxin (CTX) induced skeletal muscle injury. Following injury, PDGFRβ+ cells moved from perivascular locations into the interstitium in a distribution characteristic of fibroblasts, and showed marked induction of fibroblastic genes including αSMA and collagen1 (all p<0.0001). To confirm that αv integrins present on PDGFRβ cells critically regulate skeletal muscle fibrosis we used Itgavflox/flox;PDGFRβ-Cre mice (transgenic mice in which αv integrins are ‘knocked-down’ in PDGFRβ+ cells). These mice were significantly protected from CTX induced fibrosis (p<0.01). To demonstrate potential clinical utility of targeting αv integrins, we used a small molecule inhibitor of αv integrins (CWHM12). Treatment with CWHM12 significantly reduced fibrosis when delivered from the time of injury (p<0.01) and when delivered after the fibrotic response had become established (p<0.01). We have identified a core pathway regulating fibrosis in skeletal muscle. Pharmacologic inhibition of αv integrins has potential clinical utility in the treatment and prevention of skeletal muscle fibrosis

Aims

Complex joint fractures of the lower extremity are often accompanied by soft-tissue swelling and are associated with prolonged hospitalization and soft-tissue complications. The aim of the study was to evaluate the effect of vascular impulse technology (VIT) on soft-tissue conditioning in comparison with conventional elevation.

Nanoscale topography increases the bioactivity of a material and stimulates specific responses (third generation biomaterial properties) at the molecular level upon first generation (bioinert) or second generation (bioresorbable or bioactive) biomaterials. We developed a technique (based upon the effects of nanoscale topography) that facilitated the in vitro expansion of bone graft for subsequent implantation and investigated the optimal conditions for growing new mineralised bone in vitro. Two topographies (nanopits and nanoislands) were embossed into the bioresorbable polymer Polycaprolactone (PCL). Three dimensional cell culture was performed using double-sided embossing of substrates, seeding of both sides, and vertical positioning of substrates. The effect of Hydroxyapatite, and chemical stimulation were also examined. Human bone marrow was harvested from hip arthroplasty patients, the mesenchymal stem cells culture expanded and used for cellular analysis of substrate bioactivity. The cell line specificity and osteogenic behaviour was demonstrated through immunohistochemistry, confirmed by real-time PCR and quantitative PCR. Mineralisation was demonstrated using alizarin red staining. Results showed that the osteoinduction was optimally conferred by the presence of nanotopography, and also by the incorporation of hydroxyapatite (HA) into the PCL. The nanopit topography and HA were both superior to the use of BMP2 in the production of mineralised bone tissue. The protocol from shim production to bone marrow harvesting and vertical cell culture on nanoembossed HaPCL has been shown to be reproducible and potentially applicable to economical larger scale production

Despite its clinical significance, metaphyseal fracture healing has received little attention in research and experimental models have been limited. In particular it is not known to what extent the mechanical environment plays a role in metaphyseal fracture healing. Recently, a new murine internal fixation plate has been developed to stabilise fractures in the distal femur under highly standardised conditions. Goal of the current study was to modify this design, in order to be able to evaluate the influence of the fixator bending stiffness on metaphyseal fracture healing in mice. Adapting the existing single body design, resulting in low flexibility fixation, two new plates were developed with a decreased bending stiffness of approximately 65% and 45% of the original implant (100%). Pilot experiments were performed on 54 animals, whereas the mice were sacrificed and fracture healing assessed radiologically and biomechanically after 14 and 28 days. MicroCT evaluation confirmed that the osteotomy was created in the trabecular, metaphyseal bone of the distal mouse femora. All bones showed progressive fracture healing over time, with decreased implant stiffness leading to increased periosteal callus formation. These implants represent an important new research tool to study molecular and genetic aspects of metaphyseal fracture healing in mice under standardized mechanical conditions, in order to improve clinical treatment in challenging situations, such as in osteoporotic bone

Since osteoimmunology is gaining increasingly interest and evidence for involvement of complement in bone biology was found, the role of complement in bone biology and fracture healing was evaluated. After characterizing the bone phenotype, a fracture healing experiment with C3- and C5- deficient mice was performed. After osteotomy of the right femur and external fixation, healing was analyzed after 1, 3, 7 and 21 days. Bone characterization revealed a reduced number of osteoclasts in C5-deficient animals with a significantly reduced resorption activity. While bone mineral density was significantly higher in complement-deficient strains, stiffness was significantly reduced. After 21 days of fracture healing, C5-deficient animals showed reduced stiffness and a smaller callus volume compared to controls. Interestingly, C3- more than C5-deficient animals showed reduced bone formation. Altogether, bone phenotype of complement-deficient animals resembles a mild form of osteopetrosis. This might be due to the resorption defect seen in C5-deficient mice. A reason for the minor involvement of C3-deficient mice compared to the C5-deficient animals could be the cross-talk between the coagulation cascade with side activation of complement factor C5 by thrombin. These results indicate for the first time an essential role of complement in bone biology and fracture healing. Future studies should focus on the molecular basis of complement involvement and the osteoclastic resorption defect

We hypothesise that the Masquelet induced membrane used for the reconstruction of large bone defects were likely to involve mesenchymal stem cells (MSCs), given the excellent resultant skeletal repair. This study represents the first characterisation in humans of the induced membrane formed as a result of the Masquelet technique. Methods. Induced membranes and matching periosteum were harvested from 7 patients. Cytokines (BMP2, VEGF, SDF1) and cell lineage markers (CD31, CD271, CD146) were studied by immunohistochemisty. Flow cytometry was used to measure the cellularity and cellular composition. MSCs were enumerated using a colony forming unit fibroblast assay. In expanded cultures, a 96-gene array card was used to assess their transcriptional profile. Alkaline phophatase, alizarin red and calcium assays were employed to measure their in vitro osteogenic potential. Results. Membrane was more cellular(p=0.028), had more MSC phenotype(p=0.043) compared to matched periosteum. The molecular profiles were similar, except for 2-fold abundance of SDF-1 in membrane (p=0.043)compared to periosteum. Membrane and periosteum had a similar proportion of endothelial cells and CFU-F colonies; expanded MSCs from both sources were highly osteogenic. Discussion. These results indicate that the induced membrane possesses a rich source of MSC and therefore our findings support the view that the induced membrane plays an active role in bone regeneration

Mechanical loading of bone is anabolic, while aseptic loosening of implants is catabolic. In a rat model of mechanically induced aseptic loosening, osteoclast differentiation is increased dramatically but the underlying mechanism is unknown. The objective was to profile molecular pathways in peri-implant bone resorption. Microarrays on cortical bone samples exposed to pressurized fluid flow were performed 3, 6, 12, 24 and 36 hrs, using time 0 as controls. Of a total of 4093 genes that underwent a 1.25-fold change (p<0.05) due to fluid flow only 21 were common for all time points. Signals linked to inflammation and apoptosis were regulated in a biphasic manner at 3 and 12 and/or 24 hrs. The acute response at 3 hrs was associated with increases in the cytokines IL-6, IL-11, LIF and STAT3. Levels of the pro-apoptotic factor TWEAK were higher while those of BOK, a second pro-survival molecule, were lower. There is an early and late rise in RIPK3, which stimulates a form of programmed necrosis. Osteoblast-related genes were clearly suppressed (osteocalcin, Col1a, PTHr1), while those regulating macrophage and osteoclast differentiation (CSF-1, Bach1, HO-1, RANKL, RANK, OPG) were enhanced. These data suggest that mechanical loading of cortical bone stimulates time-dependent expression of genes regulating the survival, necrosis and differentiation of both the myeloid and mesenchymal cell lineages, resulting in an integrated response leading to a rapid increase in osteoclast numbers

Background. Impaction bone grafting with milled human allograft is the gold standard for replacing lost bone stock during revision hip surgery. Problems surrounding the use of allograft include cost, availability, disease transmission and stem subsidence (usually due to shear failure of the surrounding allograft). Aims. To investigate various polymers for use as substitute allograft. The ideal graft would be a composite with similar mechanical characteristics as allograft, and with the ability to form de novo bone. Methods. High and low molecular weight (MW) forms of three different polymers (polylactic acid (PLA), poly (lactic-co-glycolic) acid (PLGA) and polycaprolactone (PCL)) were milled, impacted into discs, and then tested in a custom built shear testing rig, and compared to allograft. A second stage of the experiment involved the addition of skeletal stem cells (SSC) to each of the milled polymers, impaction, 8 days incubation, and then tests for cell viability and number, via fluorostaining and biochemical (WST-1, DNA) assays. Results. The shear strengths of both high/ low MW PLA, and high/low MW PLGA were significantly higher than those of milled allograft but high and low MW PCL was poor to impact, and had significantly lower shear strengths. Fluorostaining showed good cell survival on high MW PLA, high MW PCL and both high and low MW PLGA. These findings were confirmed on both DNA and WST-1 assays. Conclusions. High MW PLA as well as high and low MW PLGA performed well both in mechanical testing and cell compatibility studies. These three polymers are good contenders to produce a living composite for use as substitute human allograft in impaction bone grafting

Introduction. A tibial insert with choices in size, thickness, and posterior slope is proposed to improve ligament balancing in total knee arthroplasty. However, increasing posterior slope, or the angle between the distal and proximal insert surfaces, will redistribute ultra-high molecular weight polyethylene (UHMWPE) thickness in the sagittal plane, potentially affecting wear. This study used in-vitro testing to compare wear for a standard cruciate-retaining tibial insert (STD) and a corresponding 6° sloped insert (SLP), both manufactured from direct-compression molded (DCM) UHMWPE. Our hypothesis was slope variation would have no significant effect on wear. Methods. Two of each insert (STD and SLP) were tested on an Instron-Stanmore knee simulator with a force-control regime. The gait cycle and other settings followed ISO 14243-1 and -2, except for reference positions. The STD insert was tilted 6° more than the SLP insert to level the articular surfaces. Wear was gravimetrically measured at intervals according to strict protocol. Results. No statistical difference (p=0.36) in wear rates was found for the STD (9.5 ±1.8 mg/Mc)) and SLP (11.4 ±0.5 mg/Mc) inserts. Discussion. The overall wear rate measured was higher than previously published rates for implants similar to the STD inserts. This may result from increased shear loads due to the shift in reference position and 6° slope. This is the first time the effect of tibial insert slope on wear has been evaluated in-vitro. For inserts made from DCM UHMWPE with a slope limited to 6°, this test suggests altering tibial insert slope has an insignificant effect on wear

Introduction. Rapid identification of bacteria from extemporaneous samples would greatly help management of prosthesis joint infection. The aim of the present retrospective study was to evaluate a new molecular assay (GeneXpert MRSA-SA SSTI (Cepheid)) for detecting Staphylococcus aureus (SA) and methicillin resistance directly from bone and joint samples in less an hour (58 minutes). Material et method. Retrospective study using 91 frozen samples (76 patients) of joints (n=24), bone biopsies (n=42) and tissue biopsies (n=25):. -. SA positive samples: n=72 (methicillin susceptible SA (MSSA), n=63; methicillin resistant MRSA, n=9). -. SA positive samples: n=19. The results were compared with routine results (culture in solid and liquid medium, identification and susceptibility test) from each participating lab. Results. The 72 SA positive samples gave:. -. 68 concordant positive results comprising:. . 9 MRSA positive samples,. . 56 MSSA positive samples,. . 3 MSSA positive samples, positive for SA but with inconclusive results for methicillin resistance. -. 4 negative discordant results for MSSA positive samples. The 19 SA negative samples gave:. . 16 concordant negative results. . 3 SASM positive results for negative culture of samples obtained from patients with other MSSA positive deep or superficial samples, suggesting a higher sensitivity for the GeneXpert test than culture in these cases. Sensitivity and specificty for bone and joint samples:. Se=68/72=94.4%. Sp=16/16=100%. Conclusion. The GeneXpert MRSA-SA SSTI assay provides 58-minute detection of MSSA and MRSA directly from bone and joint samples. Sensitivity and specificity were excellent in this preliminary study. This test may enable real-time peroperative diagnosis of Staphylococcus aureus, which could be very useful in the field of revision surgery. Further prospective studies should be done to accurately determine the PPV, NPV, and clinical and pharmaco-economic impact of this test in the setting of prosthesis joint infection

INTRODUCTION. Cementless Total Hip Replacement surgery is a well established procedure for relative young patients with severe hip disease. Excellent long term clinical results have been published on the performance of the femoral component. With growing clinical experience, our concern focused on excessive wear of the Ultra High Molecular Weight Polyethylene (UHMWPE) ringloc liner of the Mallory Head cementless Total Hip Prosthesis. After its introduction in our clinic in 1997, this implant is still in use without any modification. We were concerned that due to premature liner wear, the performance of this implant would not be compliant with the international guideline on implant survival (NICE guidelines: at 10 year follow up, 90% of all implants should still be in situ). Our objective was to establish the amount of liner wear in our first 200 MH implants. METHODS. Our first 200 patients consecutively treated with Mallory Head prostheses were followed up to obtain a recent digital image. Follow up was complete for 181 (90.5%) of our 200 patients. Ten had died and nine were not able or willing to come for follow up. The mean duration of follow up was 8.3 years (range: 8–13). The 181 recent digital images were classified as either excessive wear or no excessive wear by two independent orthopedic surgeons. Next, liner wear was measured in the 2D frontal plane using PolyWare Pro/3D Digital Version Rev 5.1 software (Draftware Developers, Conway, USA). A threshold for excessive liner wear was set at 0.2mm/year, according to literature. RESULTS. Using software for measuring PE wear, 46.7% of all patients had excessive UHMWPE wear (> 0.2mm/yr). There was no relation between the amount of wear and BMI, gender, component size or the acetabular inclination angle. Thirteen patients (6.5%) were revised. Nine of these revisions were for excessive liner wear or aseptic loosening (4.5%). For now, our series of cementless Mallory Head prostheses is compliant with the NICE guideline on implant survival. However, with the measured amount of wear we expect to see a significant increase in the number of revisions for liner wear in the near future. DISCUSSION. Our clinical observation of premature UHMWPE wear proved correct. The measured amount of UHMWPE wear is consistent with the few other studies published on this subject. Although we present a retrospective study, limiting the strength of our results, we have included a large group of patients with acceptable loss to follow up. It is unclear if the observed wear will lead to a sharp increase in the number of revisions within the next few years. Possibly, future revisions will be complicated by loss of acetabular bone stock following the pathofysiological reaction to wear particles. Our results can probably be generalised for any district hospital

Aims

A lack of supporting clinical studies have been published to determine the ideal length of intramedullary nail in fixation of trochanteric fractures of the hip. Nevertheless, there has been a trend to use shorter intramedullary nails for the internal fixation of trochanteric hip fractures. Our aim was to determine if the length of nail affected the outcome.

Aims

The aim of this study was to compare the functional and radiological outcomes in patients with a displaced fracture of the hip who were treated with a cemented or a cementless femoral stem.