Aim. To analyse the prevalence of culture negative periprosthetic joint infections (PJI) when adequate culture techniques are applied, and to evaluate the outcome of patients who were treated with antibiotics for a culture negative PJI versus those in whom treatment was withheld. Method. A multicenter observational study in which acute and chronic PJIs diagnosed between 2013 and 2018 were analyzed. Culture negative PJIs were diagnosed according to the MSIS, ICM and EBJIS definitions. Results. Out of the 1553 acute PJIs, none were culture negative. Out of the 1556 chronic PJIs, 70 were culture negative (4.7%) and included for further analysis. A total of 36 were treated with antibiotics (51%). After two years of follow-up, no infections occurred in patients in whom antibiotic treatment was withheld, but prosthesis extraction by any cause was observed more often in the no antibiotic group compared to the antibiotic group (32.4% versus 8.3%, P 0.012), especially in the absence of metallosis. Antibiotic treatment was the only independent predictor of prosthesis retention in the multivariate analysis (95% CI 0.15, 0.03 – 0.70). Conclusions. When adequate culture techniques are applied, the incidence of culture negative PJIs is low. If diagnosed, antibiotic treatment should be administered

Aim. Diagnosing periprosthetic joint infection after total joint arthroplasty is often challenging. The alpha defensin test has been recently reported as a promising diagnostic test for periprosthetic joint infection. The goal of this study was to determine the diagnostic accuracy of alpha defensin testing. Method. One hundred and eighty-three synovial alpha defensin and synovial fluid C-reactive protein (CRP) tests performed in 183 patients undergoing evaluation for periprosthetic joint infection were reviewed. Results were compared with the Musculoskeletal Infection Society (MSIS) criteria for periprosthetic joint infection. Results. Alpha defensin tests were performed prior to surgical treatment for infection, and 37 of these patients who had these tests were diagnosed by MSIS criteria as having infections. Among this group, the alpha defensin test had a sensitivity of 81.1% (95% confidence interval [CI], 64.8% to 92.0%) and a specificity of 95.9% (95% CI, 91.3% to 98.5%). There were 6 false-positive results, 4 of which were associated with metallosis. There were 7 false negatives, all of which were associated with either draining sinuses (n = 3) or low-virulence organisms (n = 4). A combined analysis of alpha defensin and synovial fluid CRP tests was performed in which a positive result was represented by a positive alpha defensin test and a positive synovial fluid CRP test (n = 28). Among this group, the sensitivity was calculated to be 73.0% (95% CI, 55.9% to 86.2%) and the specificity was calculated to be 99.3% (95% CI, 96.2% to 99.9%). An additional combined analysis was performed where a positive result was represented by a positive alpha defensin test or positive synovial fluid CRP test (n = 64). Among this group, the sensitivity was calculated tobe91.9%(95%CI, 78.1%to98.3%) andthe specificitywas calculated tobe79.5%(95%CI, 72.0%to85.7%). Conclusions. Alpha defensin in combination with synovial fluid CRP demonstrates very high sensitivity for diagnosing periprosthetic joint infection, but may yield false-positive results in the presence of metallosis or false-negative results in the presence of low-virulence organisms. When both alpha defensin and synovial fluid CRP tests are positive, there is a very high specificity for diagnosing periprosthetic joint infection

Aim. Low-grade infections cannot be easily distinguished from aseptic complications frequently leading to false negative diagnoses and late onset of anti-bacterial therapy. Therefore, there is a great need to establish biomarkers for early detection of low-grade infections. Method. In this study, we focused on the investigation of anti-α-defensin, anti-C3, anti-C5 and anti-C9 as potential biomarkers for infection in a cohort of hip and knee septic revision cases, taking patient characteristics and comorbidities into account. Here we included 78 patients with septic (35) and aseptic (43) (woman:37, men:42, age 50 – 93 years) revision surgeries of hip and knee. CRP serum levels and leucocyte blood values were evaluated. Patient characteristics, including age, number of prior revision surgeries and comorbidities were recorded. Periprosthetic tissue was stained histologically with Hematoxylin/Eosin and immunohistologically with different antibodies. Results. The CRP values were significantly increased in the septic cohort, but no changes were observed in leucocyte count. Interestingly, we found a strong increase in the terminal complement system component C9 (septic: 0.1% ± 0.2% aseptic: 0.01% ± 0.05%, p= 0.0004) in the septic periprosthetic tissue. The predictive value of α-defensin staining was not statistically significant (septic: 0.5% ± 0.7% aseptic: 0.1% ± 0.6%, p= 0.09). Analyzing the synovial fluid of aseptic and septic patients, the presence of C9 in the septic group (1.8 ± 0.4) was not significantly higher compared to the aseptic (1.9 ± 0.7) group. The next step was to investigate the specificity C9 detection using different joint related diseases such as chondrocalcinosis (CC), rheumatoid arthritis (RA) and metallosis. The median of C9 staining in the CC group (0 ± 0.0001) was significant lower than the infection group. Similar results have been observed in RA (0.0003 ± 0.2) and the metallosis group (0.0002 ± 0.01). Conclusions. We found a strong predictive value of anti-C9 staining for tissue infection, suggesting that C9 deposition could be a novel biomarker for the identification of periprosthetic joint infections using tissue biopsies

Introduction. The MHRA guidelines for metal on metal (MOM) suggest cobalt and chromium levels of more than 7ppb as potential for soft tissue reaction. However, in some patients soft tissue reaction is seen even in the presence of normal serum metal ions levels. Methods. A prospective review of all patients who had metal-on-metal hip arthroplasty was done. Patients who had both serum metal ion levels and MARS MRI scan were included in this study. Results. There were 574 patients with 319 females and 255 males. 240 patients had both MARS MRI scan and serum metal ions. Fifty nine (24.5%) patients with normal metal ions had metallosis/pseudo tumour on MRI scans, and 17 (7%) patients with increased metal ions had normal MRI scans. Conclusion. This study confirms that there is poor correlation between serum metal ions and soft tissue reaction. Nearly a quarter of patients with normal serum metal ions had evidence of metallosis on MRI scan. Clinicians should be aware of the potential for soft tissue reaction even in the presence of normal metal ions. Hence, consideration should be given to further imaging where appropriate, to ensure early metallosis is picked up and further complications of pseudo tumour prevented

Introduction. Osteloysis following metal-on-UHMW polyethylene Total Hip Arthroplasty (THA) is well reported, as is lack of osteolysis following Ceramic-on-Ceramic (CoC)THA. Early ceramic failures did report some osteolysis, but in flawed implants. As 3rd and now 4th generation ceramic THAs come into mid- and long-term use, the orthopaedic community has begun to see reports of high survival rates and very low incidence of osteolysis in these bearings. Osteolysis reported after 3rd generation CoC THA often included metallosis due to neck rim impingement. In our department we have revised only 2 hips in over 6000 CoC THAs for osteolysis. Both had evidence of metallosis as well as ceramic wear. The technique used by Radiologists for identifying the nature of lesions on CT is the Hounsfield score which will identify the density of the tissue within the lucent area. It is common for radiologist to have no access to previous imaging, especially pre-operative imaging if a long time has elapsed. With such a low incidence of osteolysis in this patient group, what, then, should a surgeon do on receiving a CT report on a ceramic-on-ceramic THA which states there is osteolysis? Revision of such implants in elderly patients has a high risk of morbidity and mortality. Objectives. This retrospective review aims to determine the accuracy of CT in identifying true osteolysis in a cohort of long-term third generation ceramic-on-ceramic uncemented hip arthroplasties in our department. Methods. Pelvic CT scans were performed on the first 27 patients from a cohort of 301 patients undergoing 15 year review with 3rd generation alumina-alumina cementless THAs. The average follow-up was 15 years (15–17). The CT scans were reviewed against pre-operative and post-operative radiographs and reviewed by a second musculoskeletal specialist radiologist. Results. Eleven of the CTscans were reported to show acetabular osteolysis, two reported osteolysis or possible pre-existing cyst and one reported a definitive pre-existing cyst. After review of previous imaging including pre-operative radiographs, eleven of the thirteen patients initially reported to have osteolysis were found to have pre-existing cysts or geodes in the same size and position as the reported osteolysis, and a further patient had spot-welds with stress-shielding. One patient with evidence of true osteolysis awaits aspiration or biopsy to determine if he has evidence of ceramic wear or metallosis. Conclusions. Reports of osteolysis on CT should be interpreted with care in modern ceramic-on-ceramic THA to prevent unnecessary revision. Further imaging and investigations may be necessary to exclude other conditions such as geodes, or stress shielding which are frequently confused with osteolysis on CT scans

Purpose. Complete wear-out of Polyethylene (PE) liner results in severe metallosis following articulation of the artificial head with the acetabular metal shell. We postulated that an adverse response can be led to surrounding bone tissue and new implant after revision surgery because the amount of PE wear particle is substantial and the metal particles are infiltrated in this catastrophic condition. We evaluated clinical characteristics and the survival rate of revision total hip arthroplasty (THA) performed in patients with severe metallosis following failure of PE liner. Materials and Methods. Between January 1996 and August 2004, severe metallosis following complete wear-out of PE liner were identified during revision THA in 28 hips of 28 patients. One patient had died at 7 days after surgery and 3 patients could not be reached at 5 year follow-up. Twenty-four hips of 24 patients (average age, 47.5 years) were followed for at least 6.5 years (average, 11.3 years; range, 6.5–15.9 years) and were evaluated. The mean time interval between prior surgery and the index revision surgery was 9.6 years (range, 4.0–14.3 years). The indications for revision surgery were osteolysis around well-fixed cup and stem in 22 hips and osteolysis with aseptic loosening of the cup in 2 hips. Bubble sign was observed on preoperative radiograph in 10 hips. Total revision, cup revision, and solitary bearing change were performed in 13, 10, and one hip respectively. A cementless implant was used in 23 hips and acetabular reinforcement ring was used in one. Clinical evaluation was performed using Harris hip scores and Kaplan-Meier survival analysis was performed. Multivariate analysis was performed with age, gender, BMI, bone defect type, existence of bubble sign and type of revision surgery as variables to evaluate the association with osteolysis or loosening. Results. One patient who had died from an unrelated medical condition at 6.5 years had hip that were functioning well at the time of death. Average Harris hip score improved from 64.5 points preoperatively to 81.9 points at the last follow-up. Wear and osteolysis were detected at average 8.9 years (3.1–13.5 years) after revision in 14 hips. Acetabular cup was loosened in 9 hips. Re-revision of cup was performed in 5 hips and re-revision of both cup and stem was done in 2 hips. In another hip, cup removal and artificial neck cutting was performed due to severe bone loss following two times of cup re-revision. With radiographic evidence of osteolysis as the end point, the 15-year survival rate was 35.3% (95% confidence interval [CI], 11.6%–59.0%). With radiographic loosening of any implant as the end point, the 15-year survival rate was 54.0% (95% CI, 27.9%–80.1%). Multivariate analysis revealed no variable that had a significant association with osteolysis or loosening. Conclusion. The survival rate of revision THA in patients with metallosis following a failure of a PE liner was low. Substantial amount of PE wear debris and the infiltration of metallic wear particles in the periprosthetic tissues might lead to progressive bone loss and implant loosening after revision THA

INTRODUCTION. Progressive polyethylene wear is associated with the occurrence of osteolysis, which can lead to component loosening and subsequent revision. Massive wear of the polyethylene liner may result in the penetration of the femoral head through the metal shell. Although metallosis after total hip arthroplasty has been well documented in the literature, extensive metallosis with polyethylene wear-through has been only sparsely described. The purpose of the present study was to assess clinical findings and the results of revision total hip arthroplasty in these cases. METHODS. We evaluated seven hips in five patients who underwent revision total hip arthroplasty because of metallosis with polyethylene wear-through. The average age of the patients at the time of hip revision was 70.1 years. There were granulomatous cysts surrounding the hip joint and osteolysis in the greater trochanter or in the acetabulum. Eroded metal shells with worn-through polyethylene were exchanged. Kerboull-type acetabular reinforcement device were used in five hips and GAP cup in two. Distal interlocking femoral stems were used in four hips and extensively porous-coated stems in two. All cases with osteolysis were in addition treated with bulk or morselized allograft bone. The mean duration of follow-up was 3 years. RESULTS. At the time of final follow-up evaluation, none of the hips showed osteolysis. Stable fixation of femoral and acetabular components was achieved in all cases. Bulk allograft bone was resorbed in two cases, but in all other cases grafted bones were united and improve bone stock. CONCLUSIONS. Metallosis with polyethylene wear-through caused severe synovitis and massive osteolysis. Although debridement of the surrounding metallic stained tissue could not be completely done, the clinical result of revision surgery was favorable

Metal-on-metal (MOM) hip arthroplasty has been associated with a variety of new failure modes that may be unfamiliar to surgeons who traditionally perform metal-on-polyethylene THR. These failure modes include adverse local tissue reaction to metal debris, hypersensitivity to metal debris, accelerated wear/metallosis, pseudotumours, and corrosion. A significant number of patients with metal-on-metal hip arthroplasty may present to surgeons for routine followup, concern over their implant, or frank clinical problems. A common issue with MOM hip arthroplasty that can lead to accelerated wear and failure is implant malposition. Malposition of a hard-on-hard bearing can lead to edge loading and accelerated wear at the articular surfaces, which will lead to elevation in blood metal ion levels and metallosis. Distinct from this failure mode is the possibility of metal hypersensitivity, which is believed to be an immunologically mediated reaction to normal amounts of metal debris. Because a modular MOM THR has multiple junctions and tapers that come into contact with one another, there also is the possibility of non-articular metal debris production and corrosion. This type of corrosion reaction can lead to soft tissue destruction not commonly seen with hip resurfacing. Therefore, it is important for orthopaedic surgeons to be aware of the intricacies of following a metal-on-metal hip arthroplasty and to be able to interpret test results such as metal ion levels and cross-sectional imaging. Furthermore, there is a difference in the incidence of problems depending upon the type of implant: hip resurfacing, small-diameter head metal-on-metal total hip replacement, and large diameter head MOM THR. This presentation will discuss the importance of routine monitoring and followup for patients with MOM THR, as well as the utility of measuring blood metal ion levels. The published risk stratification algorithm from the Hip Society will be reviewed

Recent reports about the excellent clinical results of unicondylar knee arthroplasty (UKA; also known as unicompartmental knee arthroplasty), by the minimally invasive approach, have encouraged the adoption of the surgical technique. However, friction between metallic prosthetic components resulting from polyethylene wear may result in the development of metallosis and the use of metal implants has become a huge issue in the worlds recently. Here, we report a case in which a patient underwent UKA and developed metallosis in soft tissues and bone adjacent to an implanted artificial joint three years postoperatively

Introduction. Hip Resurfacing Arthroplasty (HRA) has been performed in the United States for over 10 years and is an alternative to standard Total Hip Arthropastly (THA). It is appealing to younger patients with end stage osteoarthritis who seek to maintain active lifestyles. Benefits of HRA versus THR include a larger femoral ball size, potential to return to impact activities, decreased dislocation rates, and restoration of normal hip biomechanics. Patients ≤50 years old are a particularly challenging patient group to treat with THA because of their young age and high activity level, and as such, are well-suited for HRA. However, there are limited reports in the literature about clinical, radiographic and functional outcomes for this patient cohort. We present results of a clinical investigation at our institution for this patient cohort with minimum 5-year follow up, including long term survivorship and outcome scores. Methods. HRA, using the Birmingham Hip Resurfacing (BHR), was performed for 538 procedures between 2006–2009 by a single surgeon at a United States teaching hospital. After Institutional Review Board approval, medical and radiographic study records were retrospectively reviewed. Harris Hip Scores (HHS) were routinely collected. Patients who had not returned for follow-up examination were contacted by telephone for information pertaining to their status and implant, and a modified HHS was also administered. A Kaplan Meier survival curve was constructed to evaluate time to revision. Statistical analysis was performed (SAS version 9.3; SAS Institute, Cary, NC). Results. Of the 538 patients who underwent HRA from 2006–2009, 238 were aged ≤50 years (44%). Five-year follow up data was obtained from 209 of these patients (88%), using medical record documentation, and telephone survey as needed. The mean follow-up for all patients was 6 years (range 5–8 years). A total of 3% (8/238) were revised. Reasons included: (i) femoral loosening in 4, (ii) Iliopsoas impingement in 1, (iii) metallosis/adverse tissue reaction in 1, (iv) femoral neck fracture following motor vehicle accident in 1, and (v) unknown reasons in 1. Of the 238 patients, 55 (23%) were female, 2 (2/55; 3.6%) of whom have since undergone revision surgery for either metallosis/adverse tissue reaction, or unknown reasons. Of the 53 women who retained their BHR at 5-year follow up, the average HHS was 96.5. Of the 238 patients, 183 (77%) were male patients, 6 (6/183; 3.2%) of whom have since undergone revision surgery for femoral component loosening, iliopsoas impingement, or femoral neck fracture sustained in a motor vehicle accident. At 5-year follow-up, 177 male patients retained their implant and had an average Harris Hip Score of 98.8. The overall implant survival was 96.6% at approximately 5 years. Conclusion. In our cohort of patients aged ≤50 treated with BHR [Fig. 1], our results demonstrated 5-year survivorship of 96.6%, with average HHS of 98.8 in males and 96.5 in females. This study demonstrates HRA is a successful alternative to traditional THA in a challenging cohort of younger, active patients

Revision of fractured ceramic-on-ceramic total hip replacements with a cobalt-chromium (CoCr) alloy-on-polyethylene articulation can facilitate metallosis and require further expensive revision surgery [1–3]. In the present study, a fifty-two year old male patient suffered from fatal cardiomyopathy after undergoing revision total hip arthroplasty. The patient had received a polyethylene-ceramic acetabular liner and a ceramic femoral head as his primary total hip replacement. The polyethylene-ceramic sandwich acetabular liner fractured in vivo after 58 months and the patient underwent his first revision surgery where he received a Vitamin E stabilized acetabular Polyethylene (PE) liner and a CoCr alloy femoral head with documented synovectomy at that time. After 15 months, the patient was admitted to hospital in cardiogenic shock, with retrieval of the bearing components. Before the second revision surgery, peak serum cobalt levels measured 6,521 μg/L, 78-times greater than serum cobalt levels of 83μg/L associated with cobalt poisoning [4]. Serum titanium levels found in the patient measured 17.5 μg/L) normal, healthy range 0–1.4 μg/L). The retrieved CoCr alloy femoral head had lost a total of 28.3g (24% or an estimated amount of 102 × 10. −9. wear particles (∼2 μm diameter) [1]) within 16 months of in vivo service. Despite initiating a cobalt chelating therapy, the patients' cardiac left ventricular ejection fraction remained reduced at 6%. This was followed by multi-organ failure, and ultimately the patient passed away shortly after being taken off life support. Embedded ceramic particles were found on the backside and articular surfaces of the Vitamin E-stabilized PE acetabular liner. Evidence of fretting wear on the titanium (Ti) alloy acetabular shell was present, possibly explaining the increased serum Ti levels. Scanning electron microscopy and energy dispersive X-ray analyses confirmed Ti alloy transfer on the embedded ceramic particles on the backside PE liner surface and CoCr alloy transfer on the embedded ceramic particles on the articular PE liner surface. A fractured ceramic-on-ceramic total hip replacement should not be revised to a CoCr alloy-on-polyethylene articulation irrespective of concurrent synovectomy [5] as it can cause severe, third-body wear to the CoCr alloy femoral head that can lead to metallosis with fatal, systemic consequences

Introduction. The release of metallic debris can promote many adverse tissue reactions, as metallosis, necrosis, pseudotumors and osteolysis . 1–3. This debris is mainly generated by the fretting-corrosion mechanism due to the geometric difference in the head-stem interface . 4. Retrieval and in silico analysis showed the roughness of the stem-head interface appears to play an important role in the volume of material lost and THA failure . 5–7. The technical standard ISO 7206-2 recommends the measurement of average roughness (Ra) and max height of the profile (Rz) to control the quality of the surface finish of articulating surfaces on THA implants. However, despite the importance of the trunnion roughness, there is no specific requirement for this variable on the referred technical standard. The present study carried out a surface finish analysis of the trunnion of hip stems from five distinct manufacturers. Methods. Four stems (n = 4) from five (5) distinct manufacturers (A, B, C, D, and E) were used to evaluate the roughness of the trunnion. All the stems are similar to the classical Exeter stem design, with a 12/14 taper and a polished body surface. The roughness of trunnions was evaluated according to ISO 4287 and ISO 13565-2. The total assessment length was 4.8 mm with 0.8 mm cut-off. The first and last 8.33% of assessment length were not considered. The measurements of all samples were made in a rugosimeter with 2 µm feeler ITP (Völklingen, Germany), the velocity of 0.5 mm.s. -1. , and a force of 1.5 mN. The calibration was made at 20 ºC and relative humidity at 50%. The Kruskal Wallis with post hoc Nemenyi test was used to evaluate the difference of Ra among the manufacturers. The confidence level was set at 5%. Results and Discussion. The analysis of surface finish revealed different roughness among the manufactures (p < 0.005), with Ra between 0.061 µm to 3.184 µm and Rz varying of 0.41 µm to 12.69 µm. The manufacturers A and E had a Ra (2.587±0.050 µm and 3.146±0.031µm) of the trunnion similar to founded by Panagiotidou et al (2013). Within such range, the trunnion has shown a high presence of pit . 8. The manufacturer C, on the other hand, had the best surface finish of the trunnion (Ra = 0.069±0.010 µm and Rz = 0.505 ± 0.076 µm). This more smooth surface might increase the taper strength, reduce the shear stress and the susceptibility to the fretting-corrosion damage . 4,8. . Conclusion. The results were worrying because there is great variability of roughness among the manufacturers with the occurrence of trunnions with roughness too high. Nevertheless, the ISO technical standard does not recommend any procedure or minimum parameters acceptable for the surface finish of the trunnion. The revision of ISO 7206-2 would guarantee better control of trunnion roughness to reduce the amount of metallic debris and increase the safety of THA implants. Additional research is needed to determine a target value for this variable. For any figures or tables, please contact authors directly

Purpose. Despite the increasing interest and subsequent published literature on hip resurfacing arthroplasty, little is known about the prevalence of its complications and in particular the less common modes of failure. The aim of this study was to identify the prevalence of failure of hip resurfacing arthroplasty and to analyse the reasons for it. Method. From a multi-surgeon series (141 surgeons) of 5000 Bimingham hip resurfacings we have analysed the modes, prevalence, gender differences and times to failure of any hip requiring revision surgery. Results. To date 182 hips have been revised (3.6%). The most common cause for revision was a fracture of the neck of the femur (54 hips, prevalence 1.1%), followed by loosening of the acetabular component (32 hips, 0.6%), collapse of the femoral head/avascular necrosis (30 hips, 0.6%), loosening of the femoral component (19 hips, 0.4%), infection (17 hips, 0.3%), pain with aseptic lymphocytic vascular and associated lesions (ALVAL)/metallosis (15 hips, 0.3%), loosening of both components (5 hips, 0.1%) dislocation (5 hips, 0.1%) and malposition of the acetabular component (3 hips, 0.1%). In two cases the cause of failure was unknown. Comparing men with women, we found the prevalence of revision to be significantly higher in women (women = 5.7%; men = 2.6%. p<0.001). When analysing the individual modes of failure we found women to have significantly more revisions for loosening of the acetabular component, dislocation, infection and pain/ALVAL/metallosis (p<0.001, p=0.004, p=0.008, p=0.01 respectively). The mean time to failure was 2.9 years (0.003 to 11.0) for all causes, with revisions for fracture of the neck of the femur occurring earlier than other causes (mean 1.5 years, 0.02 to 11.0). There was a significantly shorter time to failure in men (mean 2.1 years, 0.4 to 8.7) compared with women (mean 3.6 years, 0.003 to 11.0) (p<0.001). Conclusion. Hip resurfacing has its own unique set of complications, including fracture of the neck of the femur. It is important to understand the prevalence of complications as well as the risk factors in order to appropriately select patients and adequately inform them prior to hip resurfacing arthroplasty

Increased modularity of total hip arthroplasty components has occurred, with theoretical advantages and disadvantages. Recent literature indicates the potential for elevated revision rates of modular neck systems and the potential for metallosis and ALVAL (Aseptic Lymphocyte dominated Vasculitis Associated Lesion) formation at the modular neck/stem site. Retrieval analysis of one modular neck implant design including SEM (Scanning Electron Microscopy) assessment was done and correlated to FEA (Finite Element Analysis) as well as clinical features of patient demographics, implant and laboratory analysis. Correlation of the consistent corrosion locations to FEA indicates that the material and design features of this system may result in a biomechanical reason for failure. The stem aspect of the modular neck/stem junction may be at particular risk

Ceramic-on-ceramic bearings provide a solution to the osteolysis seen with traditional metal-on-polyethylene bearings. Sporadic reports of ceramic breakage and squeaking concern some surgeons and this bearing combination can show in vivo signs of edge loading wear which was not predicted from in vitro studies. Taper damage or debris in the taper between the ceramic and metal may lead to breakage of either a ceramic head or insert. Fastidious surgical technique may help to minimise the risk of ceramic breakage. Squeaking is usually a benign complication, most frequently occurring when the hip is fully flexed. Rarely, it can occur with each step of walking when it can be sufficiently troublesome to require revision surgery. The etiology of squeaking is multifactorial in origin. Taller, heavier and younger patients with higher activity levels are more prone to hips that squeak. Cup version and inclination are also relevant factors. Osteolysis following metal-on-UHMW polyethylene Total Hip Arthroplasty (THA) is well reported. Earlier generation ceramic-on-ceramic bearings did produce some osteolysis, but in flawed implants. As third and now fourth generation ceramic THAs come into mid- and long-term service, the orthopaedic community has begun to see reports of high survival rates and very low incidence of osteolysis in these bearings. The technique used by radiologists for identifying the nature of lesions on Computed Tomography (CT) scan is the Hounsfield score which will identify the density of the tissue within the lucent area. Commonly the radiologist will have no access to previous imaging, especially pre-operative imaging if a long time has elapsed. With such a low incidence of osteolysis in this patient group, what, then, should a surgeon do on receiving a CT report on a ceramic-on-ceramic THA, which states there is osteolysis? This retrospective review aims to determine the accuracy of CT in identifying true osteolysis in a cohort of long-term third generation ceramic-on-ceramic uncemented hip arthroplasties in our department. Pelvic CT scans were performed on the first 27 patients from a cohort of 301 patients undergoing 15-year review with third generation alumina-alumina cementless THAs. The average follow-up was 15 years (15–17). The CT scans were reviewed against pre-operative and post-operative radiographs and reviewed by a second musculoskeletal specialist radiologist. Eleven of the CT scans were reported to show acetabular osteolysis, two reported osteolysis or a possible pre-existing cyst and one reported a definitive pre-existing cyst. After review of previous imaging including pre-operative radiographs, eleven of the thirteen patients initially reported to have osteolysis were found to have pre-existing cysts or geodes in the same size and position as the reported osteolysis, and a further patient had spot-welds with stress-shielding. One patient with evidence of true osteolysis awaits aspiration or biopsy to determine if he has evidence of ceramic wear or metallosis. Reports of osteolysis on CT should be interpreted with care in modern ceramic-on-ceramic THA to prevent unnecessary revision. Further imaging and investigations may be necessary to exclude other conditions such as geodes, or stress shielding which are frequently confused with osteolysis on CT scans

Introduction. Trabecular titanium implants are 3D printed with a high-friction ingrowth surface that is continuous with the rest of the acetabular shell. The ability to “face-change” following optimum seating of the component allows unprecedented levels of versatility in acetabular orientation. Bolt-on augments enable rapid trialling and definitive insertion of a monobloc construct. The use of these implants has rapidly increased in the National Joint Registry over the last three years with little published outcome data. We present one of the largest studies using this material. Objectives. This study assesses the early stability, ingrowth and clinical outcome of revision acetabular reconstruction with trabecular titanium. Methods. 120 consecutive acetabular revisions were prospectively evaluated radiographically and clinically with a 2 to 5 year follow-up. Results. The indications for revision were aseptic loosening (84) infection (20), dislocation/ instability (9), metallosis (6) and impingement (1). The defects were classified as type I in 2 cases, IIA in 26, IIB in 47, IIC in 15, IIIA in 25 and IIIB in 5. External augments were used in 16 cases and face changing liners in 40 cases. Mean preoperative Oxford Hip Score was 24 (range 13–33) with a postoperative mean score of 36 (range 13–46). No patients were lost to follow-up which was from 2 to 4 years (mean 3 years). Two cases were subsequently revised for infection and two for instability. One case was revised for material failure as a result of a cross-threaded screw. There were no cases of aseptic loosening and all remaining implants appear well-integrated radiographically. Conclusions. These early results are very encouraging with excellent initial stability clinically and radiographically. The versatility of face-changing liners, multiple bearing options and bolt-on augments allows rapid and accurate reconstruction. The data support the use of this material and we will continue to report the outcome of this series

Aim. A key of success in the treatment of prosthetic joint infection (PJI) is the proper diagnosis. There is a lack of diagnostic tools able to diagnose a PJI with high accuracy. Alpha-defensin has been proposed as possible solution but the available literature is still limited. This prospective study was carried out in order to determine (1) what is the sensitivity, the specificity, the positive and the negative predictive value of the Alpha-defensin immunoassay test in diagnosing PJI; (2) which clinical features may be responsible for false positive and false negative results?. Method. Preoperative aspiration was performed in patients presenting with a painful hip/knee arthroplasty. Metallosis, other inflammatory comorbidities and previous/concomitant antibiotic therapy were not considered as exclusion criteria. Patients with inadequate amount of synovial fluid for culture were excluded. At time of revision synovial fluid samples were taken in the OR in order to perform Alpha-defensin assay. During surgical debridement tissue samples for cultures were obtained. Prospectively, 156 patients (65 knees and 91 hips) were included. A diagnosis of PJI was confirmed in 29 patients. Results. The sensitivity of the Alpha-defensin immunoassay was 97% (95% CI, 92% – 99%), the specificity was 97% (95% CI, 92% – 99%), the positive predictive value was 88% (95% CI, 81% – 92%) and the negative predictive value was 99% (95% CI, 96% – 99%). Among four false positive patients two had a metallosis and one had a polyethylene wear. The false negative case presented with a draining sinus, and intraoperative cultures were also negative. Conclusions. Alpha-defensin assay may have a significant role in PJI diagnosis. Negative tests may exclude the diagnosis of PJI. Positive tests are very much likely to confirm PJI, but other conditions (metallosis, poly wear) should be excluded

We report a case of fatal heart failure caused by cobalt intoxication after revision THR in the patient who successfully underwent re-revision THR. 53-year old male presented to emergency room in our hospital with progressive shortness of breath. Symptom was started about 6 months ago so he visited local hospital. He worked up for worsening dyspnea. Simple chest radiograph and enhanced heart MRI study were performed and they showed bilateral pericardial and pleural effusion. There was no evidence of ischemic change. Transthoracic echocardiogram showed the evidence of heart failure, left ventricular ejection fraction(EF) was 40%. He was admitted at local hospital and started on vasopressors but urine output was decreased and follow-up echocardiogram showed a 25% of EF. Patient recommended heart transplantation and transferred our hospital emergency room. He underwent sequential bilateral total hip arthroplasties using CoP bearing surfaces. At 12 years postoperatively, he presented to the other hospital with acute onset of left hip pain. He was diagnosed ceramic head fracture on his left hip. Head and liner change revision surgery was performed using Cobalt-Chrome alloy 28mm metal head and Protruded cross-linked polyethylene liners. In our hospital, the patient admitted cardiovascular department of internal medicine. Patient complained nonspecific fatigue and general weakness but had no other symptoms such as visual and hearing loss, cognitive dysfuction. During work-up, patient presented progressive left hip pain and complaint of discomfort for the mass on the left groin. He also complained Left leg weakness and numbness. Simple radiograph and enhanced CT study was done. Simple radiograph image shows radiodense area around the hip joint and radiologist suspected heterotopic ossification. The cardiovascular department consulted orthopedic department. In the image findings showed huge mass combined hemorrhagic component lining acetabular component extending psoas compartment and eccentric wear on cobalt-chrome alloy metal head. Also highly radiodense material was seen around neck inferor portion and severly deformed metal head was seen. It was highly suspected that metal related granuloma, which means severe metallosis. Performed heavy metals screen, cobalt levels were 397,800 μg/Land chrome levels were 236,000 μg/L suggesting cobalt toxicity. Hip joint aspiration was done for decompression as radiologic intervention and EDTA (ethylenediamine tetraacetate) chelation therapy started immediately. After 10 cycle chelating therapy, metal level was lowered cobalt levels by 255.2μg/L and chrome levels by 39.5 μg/L. When hospital day after 134, Medical condition of the patient was getting improved, we underwent revision surgery using ceramic on ceramic bearing surface. The patient discharged postoperative 79 days. Final heavy metals screen results were 27.79μg/L on cobalt and 22.17μg/L on chrome. Although there were also reported a good clinical result of revision surgery using MoP bearing, and some surgeons reluctant to use CoC articulation because of concerns about re-fracture of ceramic. But take into account like this devastating complication after cobalt-chrome wear caused by remained ceramic particles, we should carefully select which bearing is safer

Introduction. The Medicines and Healthcare Products Regulatory Agency (MHRA) of the UK have published guidelines for annual follow up of patients with metal on metal hip replacements following widespread concern regarding metallosis. Methods. We followed up 718 total hip replacements (594 stemmed hips and 124 resurfacing) with metal on metal bearing, implanted between April 1999 and August 2010 in dedicated clinics with clinical and radiological assessment along with assessment of serum metal ions. Survival was calculated using Kaplan Meier analysis. Results. Twenty two hips had already been revised at the start of recall. Mean follow up was 108 months (180 – 44). Forty four patients had deceased and forty seven were lost to follow up. Six percent of patients had high metal ion levels and radiological analysis showed that twenty two percent of cups were outside the Lewinnek's safe zone. Fifteen months into the recall process a total of forty one hips have been revised. Discussion. Our revision rates are similar to that reported in literature thus far but this could increase. Instability arising due to the extensive soft tissue damage seen in such patients could become a major concern and arthroplasty units should be prepared to deal with this

Hip resurfacing, like other orthopaedic procedures, depends for its success upon the confluence of three factors: a well-designed device, implanted using good technique, in a properly selected patient. Cleveland Clinic has had good mid-term results in more than 2,200 patients using the Birmingham device since its FDA approval in 2006. These results are quite similar to other reported series from many centers around the world. All surgery was performed using an anterolateral approach. Males accounted for 72% of the patients, and the average age was 53 years (12‐84). More than 90% of the patients had a diagnosis of osteoarthritis, and femoroacetabular impingement was the predominant pathology. The average component head size in males was 51mm, and in females 45mm. Complications were few, with no dislocations, no femoral loosening, one socket loosening, one head collapse, 2 femoral neck fractures, and 2 deep infections. There were two patients with metallosis, one due to component malposition, and one in a small, dysplastic female. There were no destructive pseudotumors. Overall survivorship at up to 8 years was more than 99%. Survivorship in young males, under age 50 with OA was 100%. New mushroom templates for head size are described. Additional imaging recommendations including a standing lateral of the pelvis, and a CT scan for femoral anteversion may be helpful in patient selection