Aims

Two-stage exchange revision total hip arthroplasty (THA) performed in case of periprosthetic joint infection (PJI) has been considered for many years as being the gold standard for the treatment of chronic infection. However, over the past decade, there have been concerns about its safety and its effectiveness. The purposes of our study were to investigate our practice, collecting the overall spacer complications, and then to analyze their risk factors.

Polymethylmethacrylate (PMMA) bone cement is strong in compression, however it tends to fail under torsion. Sufficient pressurisation and subsequent interdigitation between cement and bone are critical for the mechanical interlock of cemented orthopaedic implants, and an irregular surface on the acetabular cup is necessary for reasonable fixation at the cup-cement interface. There is limited literature investigating discrepancies in the failure mechanisms of cemented all-polyethylene acetabular cups with and without cement spacers, under torsional loading. In vitro experimental comparison of three groups of polyethylene acetabular prosthesis (PAP) cemented into prepared sawbone hemipelvises:. * PAP without PMMA spacers maintaining an equal cement mantle circumferentially. (Group 1 n=3). * PAP without PMMA spacers cemented deliberately ‘bottoming-out’ the implant within the acetabulum. (Group 2 n=3). * PAP with PMMA spacers. (Group 3 n=3). The constructs were tested to torstional failure on a custom designed setup, and statistical analysis done by a one-way ANOVA and Tukey-Welsh test. Group 3 demonstrated superior torsional resistance with a statistically significant torque of 145Nm (SD±12Nm) at failure, compared to group 2 (109Nm, SD±7Nm) and group 1 (99Nm, SD±8Nm). Group 3 experienced failure predominantly at the bone-cement interface, in contrast, Groups 1 and 2 exhibited failure predominantly at the cup-cement interface. There was no significant difference between Group 1 and 2. Qualitative analysis of the failure mode indicates the efficient redistribution of stress throughout the cement mantle, consistent with the greater uniformity of cement. PMMA spacers increase the resistance to torsional failure at the implant-cement interface. Acetabular components without spacers (Groups 1 and 2) failed at the implant-cement interface before the cement-bone interface, at a statistically significantly lower level of torque to failure. Although the PMMA spacers may reduce cement interdigitation at the cement-bone interface the torsional forces required to fail are likely supraphysiological

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

Introduction. The medical field has long held largely anecdotal beliefs that polymethyl methacrylate (PMMA) vapors are dangerous to a growing fetus, and as such, women who are pregnant should avoid exposure. This study investigates the perceptions of female orthopedic surgeons regarding PMMA cement exposure during pregnancy, and if it influences 1) currently held beliefs / practices and 2) clinical and career choices. Methods. A 23-question survey was distributed via e-mail to active members of the Ruth Jackson Orthopaedic Society and a private social media group for women in orthopedics. Questions included demographics, current usage of PMMA, previous exposure during pregnancy and/or breastfeeding, and beliefs regarding current or future willingness of exposure. Additionally, questions were asked regarding PMMA training and whether beliefs influenced specialty choices. Results. There were 278 survey responses received, of which 256 met inclusion criteria. 73% currently utilize PMMA in training/practice, and >90% of survey respondents reported awareness of risks surrounding PMMA in pregnancy. PMMA training was found to have a weak positive correlation with those who remained in the room while pregnant. 43.6% would leave the room in the future if PMMA were being used while they were pregnant, with 26.2% leaving if they were breastfeeding. 24.9% would leave if they were the primary surgeon on the case, and 8.4% admitted that PMMA exposure during pregnancy factored into which subspecialty they chose. Conclusion. This survey demonstrates a lack of consensus amongst female orthopedic surgeons regarding the risks posed by remaining in a room during pregnancy and breastfeeding while PMMA is used. Despite 90% of respondents claiming awareness of the risks of PMMA, beliefs and education practices should be examined to determine if they match the available literature. It is plausible that beliefs regarding this exposure are deterring individuals from pursuing specialties where PMMA is used regularly. For any tables or figures, please contact the authors directly

Mechanical failure due to dislocation, fracture and acetabular wear as well as persistence of infection are the main complications associated with the use of hip spacers in the treatment of periprosthetic joint infections (PJI). We have developed a novel, custom-made spacer as part of two-stage septic hip replacement and present the two- to five-year results after reimplantation. We prospectively examined a total of 73 patients over our study period in whom our new spacer technique was used. The technique includes a dual mobility inlay and a cemented straight stem in combination with antibiotic-loaded PMMA bone cement which allows full weight bearing meanwhile the interim period. The follow-up ranged between 24 and 60 months after reimplantation as second stage of a two-stage approach. The patients were contacted as part of the follow-up using a questionnaire concerning reoperation, reinfection as well as hip function by using the Harris Hip Score. 72 patients (98,6%) could be reimplanted, one patient is still using the spacer prothesis for 45 months because of excellent functional results with a Harris Hip Score of 95, nevertheless reimplantation is planned. The reinfection rate was less than 7% after reimplantation. The dislocation rate was 5%, and in total there was an overall complication rate of less than 10%. The Harris Hip Score was significantly improved. The ENDO spacer surgical technique is a promising option in the treatment of periprosthetic joint infections (PJI) for two-stage septic exchange with a low dislocation rate and good infection control after reimplantation. In addition, it enables early mobilization with the possibility of full weight-bearing in the interval between spacer implantation and reimplantation

Polymethylmethacetate (PMMA) is a bone cement used in over 725,000 primary hip arthroplasties in 2018. Cement integrity is affected by external factors, including temperature, mixing technique and moisture uptake, which can influence cement microstructure. Changes in the cement microstructure may ultimately threaten the survivorship of the implant. The introduction of enhanced recovery and various local anaesthetic infiltration techniques have been adopted in an attempt to facilitate early mobilisation and reduce length of stay. Our study aims to investigate if the mechanical properties of PMMA are altered with exposure to Ropivacaine LA. Cements were cured in three separate states (air, serum and serum with LA) and the mechanical properties tested at 24 hours and 28 days. Using Refobacin bone cement provided by ZimmerBIOMET, cylindrical molds (12×6mm) were constructed with a split-mold. The LA used was 2mg/ml Ropivacaine hydrochloride solution. Using pilot data, this study was powered to 80% and a sample size of 10 per group (n=60) was calculated. Cement samples were subjected to compressive loading using a universal testing apparatus (Zwick/Roell). Yield-strength and modulus values were extracted from the respective stress versus strain curves. Significant differences were determined by one-way anova for each time point, and Bonferroni post-hoc testing to determine significance between actual groups. At 24-hours there were no significant differences in strength or modulus between groups. At 28-day strength and modulus increased in all groups. Compared to the air group, both serum and LA groups show a significant decrease in compressive strength. The modulus for the LA group is significantly less stiff compared to the air group. The results suggest that the initial exposure to LA has a significant impact on the physical properties of the PMMA. We propose increased awareness of the potential effects this may have on the longevity and survivorship of cemented implants

Two-stage exchange revision total hip arthroplasty performed in case of infection has been considered during many years the gold standard for treatment of chronic infection. Nevertheless, during the last decade, concerns have risen regarding its safety and its efficiency. The purpose of our study was to, first investigate the spacer complications, then to analyze their risks factors. We retrospectively included 125 patients with chronic hip periprosthetic joint infection who underwent a two stage exchange revision arthroplasty performed between January 2013 and December 2019. All spacer complications were systematically collected and risk factors were analyzed. Statistical evaluation were performed using the Student and Mann-Whitney tests. Our study confirms the hypothesis of a high-risk strategy with 42% of patients who had a mechanical spacer failure and a 20% recurrence of infection during the average two years period of follow-up. We found a high rate of spacer migration (23%) and a low rate of spacer fracture (8%) compared to literature. The most important finding was that the majority of spacer complications and failures were found in a population with high medical comorbidities as highlighted by the ASA, Charlson and Lee score associations, as well as with the cardiac, pulmonary, kidney or hepatic chronic conditions. This study showed that a two-stage hip exchange revision is a high-risk procedure regarding complications and mechanical failures of PMMA spacers. In patients with high medical comorbidities, other strategies may be considered and interdisciplinary cooperation with other facilities are needed to identify and control each risk factor

Introduction. One unpredictable clinical risk with THA may be impingement of a metal cup rim against a metal femoral-neck, with concomitant release of metal particles. Our objective was to determine if metal debris could be one trigger for catastrophic MOM wear. Patients/Materials & Methods. To simulate release of metal debris, we added metal particles (CoCr #230, Ti6Al4V #340) to six 38mm MOM bearings at beginning of each simulator test interval. The weekly 500,000 cycle intervals were replicated 10 times to acquire 5-million duty cycles. Flakes of polymerized bone cement (PMMA) were scraped from a retrieved TKR and used as control debris (N = 1,300 particles; 3 MOM). Results. Metal debris turned all lubricants black within first hour of test, and consistently over the study. Cement flakes elicited no such lubricant changes. MOM wear-rates using PMMA, CoCr, and Ti64 debris were 0.3, 4.1, and 6.4 cubic millimetes per million cycles, respectively, revealing statistically significant differences. The CoCr debris allotment produced ×30 times its weight in surface wear; the Ti6Al4V debris produced ×50 times its weight in CoCr wear. Discussion. Successful MOM bearings were reputed to have low friction due to fluid-film lubrication. Nevertheless, any THA impingement that can release metal debris may compromise such thin films. This simulator study of MOM bearings running under abrasive conditions revealed that MOM wear-rates with CoCr and Ti6Al4V debris were raised ×14 and ×23 times greater than that of PMMA debris. Conclusion. The insertion of metal debris, simulating just one impingement episode in 500,000 gait cycles, created a ×30–50 times multiplier effect in production of CoCr debris. The resulting black lubricants may be directly analogous to the black tissues noted around high-wearing MOM bearings. Thus the nemesis of MOM THA may be an extreme sensitivity to 3rd-body wear particles

Aims

Refobacin Bone Cement R and Palacos R + G bone cement were introduced to replace the original cement Refobacin Palacos R in 2005. Both cements were assumed to behave in a biomechanically similar fashion to the original cement. The primary aim of this study was to compare the migration of a polished triple-tapered femoral stem fixed with either Refobacin Bone Cement R or Palacos R + G bone cement. Repeated radiostereometric analysis was used to measure migration of the femoral head centre. The secondary aims were evaluation of cement mantle, stem positioning, and patient-reported outcome measures.

Aims

This study aimed to assess the carbon footprint associated with total hip arthroplasty (THA) in a UK hospital setting, considering various components within the operating theatre. The primary objective was to identify actionable areas for reducing carbon emissions and promoting sustainable orthopaedic practices.

Introduction. Vancomycin is commonly added to acrylic bone cement during revision arthroplasty surgery. Proprietary cement preparations containing vancomycin are available but significantly more expensive. We investigated whether the antibiotic elution and mechanical strength of ‘home-made’ vancomycin containing bone cement was comparable to commercial vancomycin-impregnated cement. Methods. A total of 18 cement discs of constant size, containing either proprietary CopalG+V. ®. ; or ‘home-made’ CopalR+G. ®. with vancomycin added by hand, were made. Each disc contained the same antibiotic quantities (0.5g gentamycin, 2g vancomycin) and was immersed in ammonium acetate buffer in a sealed container. Fluid from each container was sampled at eight time points over a two week period. The concentration of gentamicin and vancomycin in the fluid was analysed using high performance liquid chromatography mass spectrometry. The impact strength of each PMMA cement preparation was measured using a Charpy-type impact tester. Results. Highest peak antibiotic concentrations were observed from the ‘home-made’ vancomycin containing cement, added as in the operating theatre. Overall antibiotic elution was, five-fold (vancomycin) and two-fold (gentamicin), greater from the ‘home-made’ mix compared to commercially mixed cement. However the ‘home-made’ cements showed greater variation in elution kinetics compared to the commercial mix. Use of a vacuum during mixing had no significant effect on antibiotic elution in any of the samples. Impact strength testing showed no significant differences between the groups. Discussion. Our findings suggest the addition of 2g vancomycin powder to gentamicin-impregnated bone cement in theatre, significantly increases elution of both antibiotics, with no significant loss of strength, compared to commercially prepared cement. Conclusion. We have found no significant advantages of expensive off-the-shelf vancomycin-impregnated bone cement and recommend the addition of vancomycin powder by hand when making cement beads and spacers

Aims

One-stage exchange for periprosthetic joint infection (PJI) in total hip arthroplasty (THA) is gaining popularity. The outcome for a repeat one-stage revision THA after a failed one-stage exchange for infection remains unknown. The aim of this study was to report the infection-free and all-cause revision-free survival of repeat one-stage exchange, and to investigate the association between the Musculoskeletal Infection Society (MSIS) staging system and further infection-related failure.

Aims

Fixation of osteoporotic proximal humerus fractures remains challenging even with state-of-the-art locking plates. Despite the demonstrated biomechanical benefit of screw tip augmentation with bone cement, the clinical findings have remained unclear, potentially as the optimal augmentation combinations are unknown. The aim of this study was to systematically evaluate the biomechanical benefits of the augmentation options in a humeral locking plate using finite element analysis (FEA).

Aims

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.

Aims

In the 1990s, a bioactive bone cement (BABC) containing apatite-wollastonite glass-ceramic (AW-GC) powder and bisphenol-a-glycidyl methacrylate resin was developed at our hospital. In 1996, we used BABC to fix the acetabular component in primary total hip arthroplasty (THA) in 20 patients as part of a clinical trial. The purpose of this study was to investigate the long-term results of primary THA using BABC.

Aims

The purpose of this study was to evaluate the biological fixation of a 3D printed porous implant, with and without different hydroxyapatite (HA) coatings, in a canine model.

Aims

We report the incidence of radiolucent lines (RLLs) using two flanged acetabular components at total hip arthroplasty (THA) and the effect of the Rim Cutter.

Aims

The aim of this study was to report the initial results of the Exeter V40 stem, which became available in 2000.

Objectives

Osteosynthesis of anterior pubic ramus fractures using one large-diameter screw can be challenging in terms of both surgical procedure and fixation stability. Small-fragment screws have the advantage of following the pelvic cortex and being more flexible.

The aim of the present study was to biomechanically compare retrograde intramedullary fixation of the superior pubic ramus using either one large- or two small-diameter screws.

A retrospective review was performed of patients undergoing primary cementless total knee replacement (TKR) using porous tantalum performed by a group of surgical trainees. Clinical and radiological follow-up involved 79 females and 26 males encompassing 115 knees. The mean age was 66.9 years (36 to 85). Mean follow-up was 7 years (2 to 11). Tibial and patellar components were porous tantalum monoblock implants, and femoral components were posterior stabilised (PS) in design with cobalt–chromium fibre mesh. Radiological assessments were made for implant positioning, alignment, radiolucencies, lysis, and loosening. There was 95.7% survival of implants. There was no radiological evidence of loosening and no osteolysis found. No revisions were performed for aseptic loosening. Average tibial component alignment was 1.4° of varus (4°of valgus to 9° varus), and 6.2° (3° anterior to 15° posterior) of posterior slope. Mean femoral component alignment was 6.6° (1° to 11°) of valgus. Mean tibiofemoral alignment was 5.6° of valgus (7° varus to 16° valgus). Patellar tilt was a mean of 2.4° lateral (5° medial to 28° lateral). Patient satisfaction with improvement in pain was 91%. Cementless TKR incorporating porous tantalum yielded good clinical and radiological outcomes at a mean of follow-up of seven-years.

Cite this article: Bone Joint J 2014;96-B(11 Suppl A):87–92.