Introduction. Pre-operative aspiration and culture is the gold standard for the diagnosis of peri-prosthetic infection. This study aimed to ascertain the diagnostic accuracy of culture of joint aspiration with or without saline re-aspiration in the event of a dry-tap. Patients/Materials & Methods. Retrospective analysis of 343 hip aspirations in patients deemed to have moderate-high risk of infection and ultimately proceeded to revision arthroplasty over 12 years at a large quaternary referral centre where pre-operative aspiration is routine. Results. Fluid was aspirated in 141(41%) cases and dry taps in which saline injection-re-aspiration was performed occurred in 202 (59%) cases. Overall sensitivity and specificity of diagnostic aspirate were 82% (74–88%) and 79% (74–84%) respectively. Sensitivity and specificity of saline injection-re-aspiration after dry tap were 79% (64–87%) and 86% (78–92%) compared to 84% (74–91%) and 74% (66–81%) for direct aspiration. Discussion. Pre-operative joint aspiration and culture is a sensitive and specific test for the confirmation of diagnosis in patients at a moderate to high risk of prosthetic joint infection. Culture of saline injection-re-aspiration also provides accurate diagnostic information in the event of a dry tap. Both methods allow susceptibility testing of relevant organisms and are therefore able to guide peri-operative and cement instilled antibiotic therapy. Conclusions. Culture of pre-operative joint aspirates provides sensitive and specific diagnostic information, including antimicrobial susceptibility results. Saline injection-re-aspiration is a useful additional technique in those patients in whom fluid cannot be aspirated

No single test is 100% sensitive and specific for the diagnosis of prosthetic joint infection. Joint aspiration is currently the only preoperative investigation that can establish the identity of the infecting organism and its antibiotic susceptibilities. Frequently when attempting to aspirate a joint a ‘dry tap occurs as fluid cannot be aspirated. In this situation, normal saline may be injected into the joint and then reaspirated to provide fluid for culture. The aim of this study was to ascertain the diagnostic accuracy of culture of joint aspiratie with or without saline reaspiration in the event of a dry tap. A retrospective analysis of 580 hip and knee aspirations in patients deemed to have moderate-high risk of infection and ultimately proceeded to revision arthroplasty over 12 years at a large quaternary referral centre where pre operative aspiration is routine. Fluid was aspirated in 313 (54%) cases and dry taps in which saline injection reaspiration was performed occurred in 267 (46%) cases. Overall sensitivity and specificity of diagnostic aspiration were 84% (78–89%) and 85% (81–88%) respectively. Sensitivity and specificity of saline injection-reaspiration after dry tap were 87% (79–82%) and 79% (72–84%) compared to 81% (71–88%) and 90% (85–93%) for direct aspiration. Pre operative joint aspiration and culture is a sensitive and specific test for the confirmation of diagnosis in patients at a moderate to high risk of prosthetic joint infection. Culture of saline injection-reaspiration also provides accurate diagnostic information in the event of a dry tap. Both methods allow susceptibility testing of relevant organisms and are therefore able to guide peri-operative and cement instilled antibiotic therapy. Culture of pre operative joint aspirates provides sensitive and specific diagnostic information including antimicrobial susceptibility results. Saline injection-reaspiration is a useful additional technique in those patients in whom fluid cannot be aspirated

Retained polymethylmethacrylate (PMMA) debris in surgical instrument trays is a rare, but disquieting situation for the arthroplasty surgeon. Although retained debris could be considered to be sterile after autoclaving, there is no peer-reviewed literature to support this assumption. This uncertainty and subsequent fear of contamination from this bioburden often leads to operating room personnel turning over entire surgical tables and opening new surgical instruments, which consumes time and burdens a hospital's sterilization infrastructure. Consequently, the purpose of the current study was to determine if retained, heavily contaminated PMMA in surgical trays could be effectively sterilized through clinically utilized autoclave protocols. MSSA (Xen36, Perkin Elmer) biofilm was grown on identically sized PMMA (Palacos R) coupons for 72-hour duration. Following incubation, coupons were exposed to three commonly used sterilization protocols. Cobalt-Chrome (CC) coupons were included in the same tray, replicating instruments in proximity to retained PMMA. Autoclave protocols included: 1.) Single Instrument Flash protocol: Pre-vac, 270° F, 10 min exposure, 1 min drying, 2.) One Tray OR protocol: Pre-vac, 270° F, 4 min exposure, 1 min drying, and 3.) Standard Post-Operative protocol: Pre-vac, 270° F, 10 min exposure, 60 min drying. Control coupons did not undergo autoclaving. Coupons were then sonicated for 30 minutes in tryptic soy broth and plated to count CFUs. Experiments were performed in quadruplicate. Control coupons showed significant contamination with CFU counts in the range of 10. 6. CFU/mL. CFU counts of zero across all autoclaved PMMA and CC coupons revealed that each protocol was effective in completely eradicating culturable S. aureus, confirming clinical efficacy on orthopaedic cement sterilized in surgical trays. Our findings demonstrate that heavily contaminated PMMA and exposed metal in surgical trays can be effectively sterilized through several autoclaving protocols. Clinicians should feel confident in the efficacy of autoclave protocols in removing bacteria and its associated biofilm from othopaedic materials

Fracture of contemporary femoral stems is a rare occurrence. Earlier THR stems failed due to design issues or post manufacturing heat treatments that weakened the core metal. Our group identified and analyzed 4 contemporary fractured femoral stems after revision surgery in which electrochemical welds contributed to the failure. All four stems were proximally porous coated titanium alloy components. All failures occurred in the neck region post revision surgery in an acetabular cup exchange. All were men and obese. The fractures occurred at an average of 3.6 years post THR redo (range, 1.0–6.5 years) and 8.3 years post index surgery (range, 5.5–12.0 years). To demonstrate the effect of electrocautery on retained femoral stems following revision surgery, we applied intermittent electrosurgical currents at three intensities (30, 60, 90 watts) to the polished neck surface of a titanium alloy stem under dry conditions. At all power settings, visible discoloration and damage to the polished neck surface was observed. The localized patterns and altered metal surface features exhibited were like the electrosurgically-induced damage priorly reported. The neck regions of all components studied displayed extensive mechanical and/or electrocautery damage in the area of fracture initiation. The use of mechanical instruments and electrocautery was documented to remove tissues in all 4 cases. The combination of mechanical and electrocautery damage to the femoral neck and stem served as an initiation point and stress riser for subsequent fractures. The electrocautery and mechanical damage across the fracture site observed occurred iatrogenically during revision surgery. The notch effect, particularly in titanium alloys, due to mechanical and/or electrocautery damage, further reduced the fatigue strength at the fractured femoral necks. While electrocautery and mechanical dissection is often required during revision THA, these failures highlight the need for caution during this step of the procedure in cases where the femoral stem is retained

Introduction. Surgical simulation and ‘virtual’ surgical tools are becoming recognised as essential aids for speciality training in Trauma & Orthopaedics, as evidenced by the BOA T&O Simulation Curriculum 2013. 1,2. The current generation of hip arthroplasty simulators, including cadaveric workshops, offers the trainee limited exposure to reproducible real life bony pathology. We developed and implemented a novel training course using pathological dry bone models generated from real patient cases to support senior orthopaedic trainees and new consultants in developing knowledge and hands on skills in complex total hip arthroplasty. Patient/Materials & Methods. A two-day programme for 20 delegates was held at a specialist centre for hip arthroplasty. Three complex femoral and three complex acetabular cases were identified from patients seen at our centre. 3D models were printed from CT scans and dry bone models produced (using a mold-casting process), enabling each delegate to have a copy of each case at a cost of around £30 per case per delegate (Figure 1). The faculty was led by 4 senior Consultant revision hip surgeons. A computerised digitising arm was used to measure cup positioning and femoral stem version giving candidates immediate objective feedback (Figure 2). Candidate experience and satisfaction with the course and models was evaluated with a standardised post-course questionnaire. Results. 91% of respondents rated overall course satisfaction good or very good with 100% stating learning objectives were met or exceeded. 100% of delegates rated the bone model workshop cases as good or very good for the acetabular course, and 88% for the femoral course. Discussion. This course has been shown to enhance learning of surgical techniques and skills in complex hip surgery. Conclusion. We have developed a novel, effective and low cost training simulation method using pathological dry bone models for complex and revision hip arthroplasty which could be developed for other anatomical areas

The mechanical performance of the cement-in-cement interface in revision surgery has not been fully investigated. The quantitative effect posed by interstitial fluids and roughening of the primary mantle remains unclear. We have analysed the strength of the bilaminar cement-bone interface after exposure of the surface of the primary mantle to roughening and fluid interference. The end surfaces of cylindrical blocks of cement were machined smooth (Ra = 200 nm) or rough (Ra = 5 μm) and exposed to either different volumes of water and carboxymethylcellulose (a bone-marrow equivalent) or left dry. Secondary blocks were cast against the modelled surface. Monoblocks of cement were used as a control group. The porosity of the samples was investigated using micro-CT. Samples were exposed to a single shearing force to failure. The mean failure load of the monoblock control was 5.63 kN (95% confidence interval (CI) 5.17 to 6.08) with an estimated shear strength of 36 MPa. When small volumes of any fluid or large volumes were used, the respective values fell between 4.66 kN and 4.84 kN with no significant difference irrespective of roughening (p > 0.05). Large volumes of carboxymethylcellulose significantly weakened the interface. Roughening in this group significantly increased the strength with failure loads of 2.80 kN (95% CI 2.37 to 3.21) compared with 0.86 kN (95% CI 0.43 to 1.27) in the smooth variant. Roughening of the primary mantle may not therefore be as crucial as has been previously thought in clinically relevant circumstances

Aims

In order to release the contracture band completely without damaging normal tissues (such as the sciatic nerve) in the surgical treatment of gluteal muscle contracture (GMC), we tried to display the relationship between normal tissue and contracture bands by magnetic resonance neurography (MRN) images, and to predesign a minimally invasive surgery based on the MRN images in advance.

Aims

Periprosthetic joint infections (PJIs) with prior multiple failed surgery for reinfection represent a huge challenge for surgeons because of poor vascular supply and biofilm formation. This study aims to determine the results of single-stage revision using intra-articular antibiotic infusion in treating this condition.

Introduction. Outcomes following large joint arthroplasty are influenced by the accuracy of implant placement. Patient specific (PS) technology has been used in knee arthroplasty surgery however, its application in total hip arthroplasty remains relatively unexplored. Aims. We investigated whether conventional or PS guides, resulted in a more accurate reconstruction of the pre-operative head centre position. Methods. A pilot study, determined a minimum of 7 samples were required per group to ensure an adequately powered study. However in order to account for potential errors, ten specimens were prepared for both groups by a single surgeon and using a standardised operative technique. Both groups used instruments, available on standard operating sets, however PS guides were only used and available for the PS group. Following surgery, specimens were laser scanned to generate 3- dimensional surface models. These were then compared to models of a pre-operative specimen. The distance between the pre and post- operative femoral head centres (head position error) was then calculated. Results. This study analysed 19 implanted specimens, as one specimen was excluded due to an error in preparation. The median and range head position error was 8mm (3.5–10.3) in the conventional group and 3.9mm (2.2–7.4) in the PS group. This difference was statistically significant (U=8.5, z=−2.983, p=0.003). Discussion. We found that the use of PS guides halved the average head position error and reduced the range of errors. A difference of 4.1mm in head centre position was both statistically and clinically significant. Conclusions. PS technology improves the accuracy of hip arthroplasty surgery in a dry bone model. It would be reasonable for future studies to further assess the use of PS guides in vivo as part of a clinical trial

Aims

Femoral cement-in-cement revision is a well described technique to reduce morbidity and complications in hip revision surgery. Traditional techniques for septic revision of hip arthroplasty necessitate removal of all bone cement from the femur. In our two centres, we have been using a cement-in-cement technique, leaving the distal femoral bone cement in selected patients for septic hip revision surgery, both for single and the first of two-stage revision procedures. A prerequisite for adoption of this technique is that the surgeon considers the cement mantle to be intimately fixed to bone without an intervening membrane between cement and host bone. We aim to report our experience for this technique.

Aims

The aim of this study was to identify the minimal clinically important difference (MCID), minimal important change (MIC), minimal detectable change (MDC), and patient-acceptable symptom state (PASS) in the Forgotten Joint Score (FJS) according to patient satisfaction six months following total hip arthroplasty (THA) in a UK population.

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This study investigates head-neck taper corrosion with varying head size in a novel hip simulator instrumented to measure corrosion related electrical activity under torsional loads.

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To evaluate the effect of ultrasound-targeted simvastatin-loaded microbubble destruction (UTMD_SV) for alleviation of the progression of osteoarthritis (OA) in rabbits through modulation of the peroxisome proliferator-activated receptor (PPARγ).

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The aim of this study was to perform a cross-cultural adaptation of Oxford Hip Score (OHS) to Indonesian, and to evaluate its psychometric properties.

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To achieve the functional benefits of the direct anterior (DA) approach and the fixation benefits of cemented replacement, this study combined the two techniques posing the following questions: does the limited access of the DA approach adversely affect the cement technique?; and does such a cementing technique reduce the incidence of cementless complications?

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The aims of this study were to develop an in vivo model of periprosthetic joint infection (PJI) in cemented hip hemiarthroplasty, and to monitor infection and biofilm formation in real-time.

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Cement-in-cement revision of the femoral component represents a widely practised technique for a variety of indications in revision total hip arthroplasty. In this study, we compare the clinical and radiological outcomes of two polished tapered femoral components.

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The purpose of this study was to evaluate unexpected positive cultures in total hip arthroplasty (THA) revisions for presumed aseptic loosening, to assess the prevalence of low-grade infection using two definition criteria, and to analyze its impact on implant survival after revision.

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Of growing concern in arthroplasty is the emergence of atypical infections, particularly Cutibacterium (formerly Propionibacterium) sp. infections. Currently, the dermal colonization rate of Cutibacterium about the hip is unknown. Therefore, the aim of this study was to investigate colonization rates of Cutibacterium sp. at locations approximating anterior and posterolateral approaches to the hip joint.

Aims

The aim of this study was to develop a novel computational model for estimating head/stem taper mechanics during different simulated assembly conditions.