Aims. The aim of this study was to evaluate the performance of first-generation annealed highly cross-linked polyethylene (HXLPE) in cementless total hip arthroplasty (THA). Methods. We retrospectively evaluated 29 patients (35 hips) who underwent THA between December 2000 and February 2002. The survival rate was estimated using the Kaplan-Meier method. Hip joint function was evaluated using the Japanese Orthopaedic Association (JOA) score. Two-dimensional polyethylene wear was estimated using Martell’s Hip Analysis Suite. We calculated the wear rates between years 1 and 5, 5 and 10, 10 and 15, and 15 and final follow-up. Results. The mean follow-up period was 19.1 years (SD 0.6; 17.3 to 20.1). The 19-year overall survival rate with the end point of all-cause revision was 97.0% (95% confidence interval (CI) 91 to 100). The mean JOA score improved from 43.2 (SD 10.6; 30 to 76) before surgery to 90.2 (SD 6.4; 76 to 98) at the final follow-up (p < 0.001). There was no osteolysis or loosening of the acetabular or femoral components. The overall steady-state wear rate was 0.013 mm/year (SD 0.012). There was no hip with a steady-state wear rate of > 0.1 mm/year. There was no significant difference in wear rates for each period. We found no significant correlation between the wear rate and age, body weight, BMI, or cup inclination. Conclusion. First-generation annealed HXLPE shows excellent wear resistance and no acceleration of wear for approximately 20 years, with low all-cause revision rates. Cite this article: Bone Joint J 2022;104-B(2):200–205

There is a strong association between the presence of a calcar collar on a cementless stem and a reduced risk of revision surgery for periprosthetic fracture of the femur (PFF). A medial calcar collar may act to reduce relative movement between the implant and femur during PFF, through calcar-collar contact (CCC). The aims were:. Estimate the effect of CCC on periprosthetic fracture mechanics. Estimate the effect of initial calcar-collar separation on the likelihood of CCC. Three groups of six composite femurs were implanted with a fully coated collared cementless femoral stem. Neck resection differed between groups (group 1 = no additional resection, group 2 = 3mm additional resection, group 3 = 6mm additional resection). PFF were simulated using a previously published technique. Fracture torque and rotational displacement were measured and torsional stiffness and rotational work prior to fracture were estimated. Results between trials where CCC did and did not occur where compared using Mann-Whitney U tests. Logistic regression estimated the odds (OR) of failing with 95% confidence interval (CI) to achieve CCC for a given initial separation. Where CCC occurred fracture torque was greater (47.33 [41.03 to 50.45] Nm versus 38.26 [33.70 to 43.60] Nm, p= 0.05) and torsional stiffness was greater (151.38 [123.04 to 160.42] rad.Nm. −1. versus 96.86 [84.65 to 112.98] rad.Nm. −1. , p <0.01). CCC was occurred in all cases in group one, 50% in group two and 0% in group three. OR of failure to obtain CCC increased 3.8 fold (95% CI 1.6 to 30.2, p <0.05) for each millimetre of separation. Resistance to fracture and construct stiffness increased when a the collar made contact with the calcar prior to fracture and the chances of contact decrease with increasing initial separation at the time of implantation. Surgeons should aim to achieve a calcar-collar distance of less than 1mm following implantation to ensure CCC and to reduce the risk of fracture

Majority of ultra-high molecular weight polyethylene (UHMWPE) medical devices used in total joint arthroplasty are crosslinked using gamma radiation to improve wear resistance. Alternative methods of crosslinking are urgently needed to replace gamma radiation due to rapid decline in its supply. Peroxide crosslinking is a candidate method with widespread industrial applications. Oxidative stability and biocompatibility, which are critical requirements for medical device applications, can be achieved using vitamin-E as an additive and by removing peroxide by-products through high temperature melting, respectively. We investigated compression molded UHMWPE/vitamin-E/di-cumyl peroxide blends followed by high-temperature melting in inert gas as a material candidate for tibial knee inserts. Wear resistance increased and mechanical properties remained largely unchanged. Oxidation induction time was higher than most of the other clinically available formulations. The material passed the local-end point biocompatibility tests per ISO 10993. Compounds found in exhaustive extraction were of no concern with margin-of-safety values well above the accepted level, indicating a desirable toxicological risk profile. Peroxide crosslinked, vitamin-E stabilized, and high temperature melted UHMWPE has recently been cleared for clinical use in tibial knee inserts. With all the salient characteristics needed in a material that can provide superior long-term performance in total joint patients, peroxide crosslinking can replace gamma radiation crosslinking of UHMWPE for use in all total joint replacement implant including acetabular liners

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

Previous studies have highlighted differences in the risk of periprosthetic fracture between tapered slip (TS) and composite beam (CB) stems. This biomechanical study explored periprosthetic fractures around these stems and the effect of adding a 16-gauge calcar or diaphyseal wire to TS stems on their resistance to torque. A power analysis determined a sample size of 7 specimens per group, assuming a standard deviation of 14.8 Nm in peak torque, to provide 90% power to detect a difference of at least 30 Nm between groups. Twenty-one TS stems (eight alone, six with calcar wiring, seven with diaphyseal wiring placed 2 cm distal to the lesser trochanter) and seven CB stems were cemented into standard Sawbones. A servo-hydraulic test machine applied a 1000 N load with a 1-degree rotation per second until failure. The peak torque at failure was measured, and the fracture location recorded. Comparisons were performed using two-sample t-tests. CB stems exhibited a significantly higher peak torque at failure (205.3 Nm) than TS stems (159.5 Nm, p=0.020). Calcar-wire-TS (148.2 Nm, p=0.036) and diaphyseal-wire-TS (164.9 Nm, p=0.036) were both weaker than CB stems. Wired-TS stems showed no significant difference from non-wired-TS stems. Additionally, the study could not conclude that calcar wiring is stronger than diaphyseal wiring. All TS fractures occurred at the mid-stem, simulating a B-type fracture, while the addition of the diaphyseal wire shifted the fracture location more distally in four of seven stems (p=0.0699). This biomechanical study supports the clinical evidence that CB stems have stronger resistance to torque than TS stems and may explain lower risk of periprosthetic fracture. The addition of calcar or diaphyseal wires to TS stems resulted in no significant changes in peak torque to fracture. In patients at high risk of periprosthetic fracture, CB cemented stems should be considered

Aims. Limited implant survival due to aseptic cup loosening is most commonly responsible for revision total hip arthroplasty (THA). Advances in implant designs and materials have been crucial in addressing those challenges. Vitamin E-infused highly cross-linked polyethylene (VEPE) promises strong wear resistance, high oxidative stability, and superior mechanical strength. Although VEPE monoblock cups have shown good mid-term performance and excellent wear patterns, long-term results remain unclear. This study evaluated migration and wear patterns and clinical and radiological outcomes at a minimum of ten years’ follow-up. Methods. This prospective observational study investigated 101 cases of primary THA over a mean duration of 129 months (120 to 149). At last follow-up, 57 cases with complete clinical and radiological outcomes were evaluated. In all cases, the acetabular component comprised an uncemented titanium particle-coated VEPE monoblock cup. Patients were assessed clinically and radiologically using the Harris Hip Score, visual analogue scale (pain and satisfaction), and an anteroposterior radiograph. Cup migration and polyethylene wear were measured using Einzel-Bild-Röntgen-Analyze software. All complications and associated treatments were documented until final follow-up. Results. Clinical assessment showed persistent major improvement in all scores. On radiological assessment, only one case showed a lucent line (without symptoms). At last follow-up, wear and migration were below the critical thresholds. No cup-related revisions were needed, indicating an outstanding survival rate of 100%. Conclusion. Isoelastic VEPE cups offer high success rates and may prevent osteolysis, aseptic loosening, and the need for revision surgeries in the long term. However, longer follow-up is needed to validate our findings and confirm the advantages offered by this cup. Cite this article: Bone Jt Open 2024;5(10):825–831

Periprosthetic joint infections (PJI) are challenging complications following arthroplasty. Staphylococci are a frequent cause of PJI and known biofilm producers. Reoperations for PJI of the hip or knee between 2012 and 2015 performed at Sahlgrenska University Hospital were identified. Medical records were reviewed, and clinical parameters recorded for patients whose intraoperative bacterial isolates had been stored at the clinical laboratory. Staphylococcal strains isolated from reoperations due to first-time PJI were characterised by their ability to form biofilms using the microtiter plate test. The study group included 49 patients (70 bacterial strains) from first-time PJI, whereof 24 (49%) patients had recurrent infection. Strong biofilm production was significantly associated with recurrent infection. Patients infected with strong biofilm producers had a five-fold increased risk for recurrent infection. Strong biofilm production was significantly associated with increased antimicrobial resistance and PJI recurrence. This underscores the importance of determining biofilm production and susceptibility as part of routine diagnostics in PJI. Strong staphylococcal biofilm production may have implications on therapeutic choices and suggest more extensive surgery. Furthermore, despite the increased biofilm resistance to rifampicin, results from this study support its use in staphylococcal PJI

The trend towards more minimal access has led to a series of instruments being developed to enable adequate access for Direct Anterior Approach (DAA) for hip arthroplasty. These include longer levers, hooks attached to the operating table and a series of special attachments to the operating table to position the leg and apply traction where necessary. The forces applied in this way may be transmitted locally, damaging muscle used as a fulcrum, or the knee and ankle joints when torque has to be applied to the femur through a boot. The arthroplasty surgeon's aim is to minimise the forces applied to both bone and soft tissue during surgery. We surmised that the forces needed for adequate access were related to the extent of the capsular and soft tissue releases, and that they could be measured and optimised. with the aim of minimising the forces applied to the tissues around the hip. Eight fresh frozen specimens from pelvis to mid tibia from four cadavers were approached using the DAA. A 6-axis force/torque sensor and 6-axis motion tracking sensor were attached to a threaded rod securely fastened to the tibial and femoral diaphysis. The torque needed to provide first extension, then external rotation, adequate for hip arthroplasty were measured as the capsular structures were divided sequentially. The Zona Orbicularis (ZO) and Ischiofemoral Ligament(IFL) contributed most of the resistance to both extension (4.0 and 3.1Nm) and external rotation torque (5.8 and 3.9Nm). The contributions of the conjoint tendon (1.5 and 2.4Nm) and piriformis (1.2 and 2.3Nm) were substantially smaller. By releasing the Zona Orbicularis and Ischiofemoral Ligament, the torque needed to deliver the femur for hip arthroplasty could be reduced to less than the torque needed to open a jar (2.9–5.5Nm)

Musculoskeletal disorders have been recognised as common occupational risks for all orthopaedic surgeons. The nature of tasks performed by hip surgeons often requires both forceful and repetitive manoeuvres, potentially putting them at higher risk of musculoskeletal injuries compared to other orthopaedic sub-specialities. This study aimed to investigate the prevalence of musculoskeletal conditions among hip surgeons and evaluate the association between their workplace and lifestyle factors and musculoskeletal health. An online questionnaire consisting of 22 questions was distributed to UK-based consultant hip surgeons via email and social media platforms. This survey was completed by 105 hip surgeons. The mean age of the respondents was 49 years (range 35–69), with an average of 12 years (range 1–33) in service. 94% were full-time and 6% worked part-time. 49% worked at a district general hospital, 49% at a tertiary centre and 4% at a private institution. 80% were on the on-call rota and 69% had additional trauma commitments. 91% reported having one or more, 50% with three or more and 13% with five or more musculoskeletal conditions. 64% attributed their musculoskeletal condition to their profession. The most common musculoskeletal conditions were base of thumb arthritis (22%), subacromial impingement (20%), degenerative lumbar spine (18%) and medial or lateral epicondylitis (18%). 60% stated that they experienced lower back pain. Statistical analysis showed that being on the on-call rota was significantly (P<0.001) associated with a higher musculoskeletal burden. Regular resistance and/or endurance training and BMI<30 were statistically significant protective factors (P<0.001). Over the last few decades, most of the hip-related literature has focused on improving outcomes in patients, yet very little is known about the impact of hip surgery on the musculoskeletal health of hip surgeons. This study highlights a high prevalence of musculoskeletal conditions among UK-based hip surgeons. Hip surgeons have a pivotal role to play in the ongoing recovery of elective orthopaedics services. There is a pressing need for the identification of preventative measures and improvement in the surgical environment of our hip surgeons

Periprosthetic joint infection (PJI) causes significant morbidity. Methicillin sensitive . Staphylococcus Aureus. (MSSA) is the most frequent organism, and the majority are endogenous. Nasal MSSA colonisation is a proven risk factor for S. aureus infection. Decolonisation reduces PJIs but there is a paucity of evidence comparing treatments. Aims; compare 3 nasal decolonisation treatments at (1) achieving MSSA decolonisation, (2) preventing PJI. Our hospital trust introduced MSSA screening and decolonisation prior to hip and knee arthroplasty in 2010. Data was prospectively collected since 2013, including all MSSA carriers, decolonisation treatment received, MSSA status at time of surgery and all PJIs. Prior to 2017 MSSA carriers received nasal mupirocin or neomycin, from August 2017 until August 2019 nasal octenidine was used. During the study period 15,958 primary hip and knee replacements were performed. 3,200 (20.1%) were MSSA positive at preoperative screening and received decolonisation treatment, 698 mupirocin, 1,210 neomycin and 1,221 octenidine. Mupirocin (89.1%) and neomycin (90.9%) were more effective at decolonisation than octenidine (50.0%, P<0.0001). There was no difference in S. aureus PJI rates (P=0.452). Of those negative at original screening 9.1% were positive on the day of surgery (1,164/12,758). MSSA decolonisation is an effective method to decrease PJI rates but there is little research into the best treatment. Both mupirocin and neomycin are more effective than octenidine at achieving MSSA decolonisation. There was poor correlation between the MSSA status after treatment and PJI rates. There is debate if treatment should be targeted by screening or if all patients she be treated without screening. Global decolonisation without screening is supported by the 26.7% of carriers that were negative at original screening in our study. Further research is needed comparing decolonisation treatments to reduce PJI rates and avoid the risk of drug resistance

Introduction. Two-stage reimplantation for prosthetic joint infection (PJI) of the hip is the standard of care with a 5–10% recurrence at a minimum two-year follow-up. Compiling outcomes data for this standard of care is necessary in order to characterize long-term reinfection risk and the culpable microbiology. The purpose of this study was to determine the long-term success of two-stage reimplantation and identify the factors that affected the success. Methods. We performed a systematic review of randomized control trials, cohort studies, and case series through May 2019, searching Embase, Medline via PubMed, and Cochrane Library for the concept of two-stage reimplantation for the treatment of hip and knee PJIs, yielding 464 unique citations for abstract review, of which 135 were reviewed in full. Our parameters of interest included: reinfection and mortality events following successful reimplantation, the timing of these events, and the microbiology of index and recurrent infections. Results. Meeting our criteria were 59 studies with 4,494 patients (1,842 hips) who had completed reimplantation. Among successfully reimplanted hips, 4.76% (95% CI, 2.00–8.41) were reinfected by 24 months, 6.84% (4.92–9.02) were reinfected by final follow-up, 1.6% (0.32–3.52) were reinfected with an identical organism(s) with identical resistance, and 2.55% (0.77–5.03) were reinfected with a novel organism(s) or novel resistance. In 24 studies with reinfected patients and sufficient data, 8 studies reported an average interval from reimplantation to reinfection greater than 24 months, and 14 reported at least 1 patient with a reinfection event greater than 48 months following reimplantation. Conclusion. The results from this review determined that the host of an index PJI faces ongoing risk of recurrent infection years into the post-operative period despite initial eradication and that novel microbiology is the cause of a significant proportion of failures. For any tables or figures, please contact the authors directly

Background. Post-operative periprosthetic femoral fractures (PFF) are a devastating complication associated with high mortality and are costly. Few risk factors are modifiable apart from implant choice. The design features governing risk of PFF are unknown. We estimated the 90-day risk of revision for PFF associated with design features of cementless femoral stems and to investigate the effect of a collar on early PFF risk using a biomechanical in-vitro model. Patients, materials and methods. 337 647 primary THAs from the National Joint Registry (UK) were included in a multivariable survival and regression analysis to identify the adjusted hazard of PFF revision following primary THA using cementless stems. The effect of a collar in cementless THA on early PFF was evaluated in an in-vitro model using paired fresh frozen cadaveric femora. Results. Prevalence of PFF revision was 0.34% (1180/337647) and 44.0% occurred (520/1180) within 90 days of surgery. Implant risk factors included: collarless stem, non grit-blasted finish and triple tapered design. In the in-vitro PFF model a medial calcar collar consistently improved construct stability and fracture resistance. Discussion. During rotational injury the collar can load the calcar in compression increasing the force required for a fracture. This increases the force required to cause a PFF around a collared implant versus collarless implants. The calcar possibly acts as a check-rein which prevents excessive peri-prosthetic trabecular deformation in rotational injuries and may improve the resistance to loosening after high energy injuries which do not cause cortical fracture. Conclusion. Analysis of stem design features in registry data is a useful method to identify implant characteristics which affect the risk of early PFF around cementless femoral stems. Calcar collar reduced early PFF risk and this was confirmed by biomechanical testing. This approach may be useful in the analysis of other uncommon arthroplasty failure modes

Aims. The aim of this study was to estimate the 90-day risk of revision for periprosthetic femoral fracture associated with design features of cementless femoral stems, and to investigate the effect of a collar on this risk using a biomechanical in vitro model. Materials and Methods. A total of 337 647 primary total hip arthroplasties (THAs) from the United Kingdom National Joint Registry (NJR) were included in a multivariable survival and regression analysis to identify the adjusted hazard of revision for periprosthetic fracture following primary THA using a cementless stem. The effect of a collar in cementless THA on this risk was evaluated in an in vitro model using paired fresh frozen cadaveric femora. Results. The prevalence of early revision for periprosthetic fracture was 0.34% (1180/337 647) and 44.0% (520/1180) occurred within 90 days of surgery. Implant risk factors included: collarless stem, non-grit-blasted finish, and triple-tapered design. In the in vitro model, a medial calcar collar consistently improved the stability and resistance to fracture. Conclusion. Analysis of features of stem design in registry data is a useful method of identifying implant characteristics that affect the risk of early periprosthetic fracture around a cementless femoral stem. A collar on the calcar reduced the risk of an early periprosthetic fracture and this was confirmed by biomechanical testing. This approach may be useful in the analysis of other uncommon modes of failure after THA. Cite this article: Bone Joint J 2019;101-B:779–786

In revision total hip replacement, bone loss can be managed by impacting porous bone chips. In order to guarantee sufficient mechanical strength, the bone chips have to be compacted. The aim of this study was to determine in an in vitro simulation whether the use of a pneumatic hammer leads to higher primary stability than manual impaction. Bone mass characteristics were measured by force and distance variation of a penetrating punch, which was lowered into a plastic cup filled with bone chips. From these measurements bulk density, contact stiffness, impaction hardness and penetration resistance were calculated for different durations of impaction. We found that the pneumatic method reached higher values of impaction hardness, contact stiffness and bulk density suggesting an increase in stability of the implant. No significant differences were found between the two different methods concerning the penetration resistance. The pneumatic method might reduce the risk of fracture in vivo, as force peaks are smaller and applied for a shorter period. Results from manual impaction showed higher variability and depend much on the experience of the surgeon. The pneumatic hammer is a suitable tool to standardise the impaction process

Aims

The primary outcome was investigating differences in wear, as measured by femoral head penetration, between cross-linked vitamin E-diffused polyethylene (vE-PE) and cross-linked polyethylene (XLPE) acetabular component liners and between 32 and 36 mm head sizes at the ten-year follow-up. Secondary outcomes included acetabular component migration and patient-reported outcome measures (PROMs) such as the EuroQol five-dimension questionnaire, 36-Item Short-Form Health Survey, Harris Hip Score, and University of California, Los Angeles Activity Scale (UCLA).

We biomechanically investigated whether the standard dynamic hip screw (DHS) or the DHS blade achieves better fixation in bone with regard to resistance to pushout, pullout and torsional stability. The experiments were undertaken in an artificial bone substrate in the form of polyurethane foam blocks with predefined mechanical properties. Pushout tests were also repeated in cadaveric femoral heads. The results showed that the DHS blade outperformed the DHS with regard to the two most important characteristics of implant fixation, namely resistance to pushout and rotational stability. We concluded that the DHS blade was the superior implant in this study

Aims

The aim of this study was to determine both the incidence of, and the reoperation rate for, postoperative periprosthetic femoral fracture (POPFF) after total hip arthroplasty (THA) with either a collared cementless (CC) femoral component or a cemented polished taper-slip (PTS) femoral component.

Aims

The aim of this study was to identify the optimal lip position for total hip arthroplasties (THAs) using a lipped liner. There is a lack of consensus on the optimal position, with substantial variability in surgeon practice.

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

When performing revision total hip arthroplasty using diaphyseal-engaging titanium tapered stems (TTS), the recommended 3 to 4 cm of stem-cortical diaphyseal contact may not be available. In challenging cases such as these with only 2 cm of contact, can sufficient axial stability be achieved and what is the benefit of a prophylactic cable? This study sought to determine, first, whether a prophylactic cable allows for sufficient axial stability when the contact length is 2 cm, and second, if differing TTS taper angles (2° vs 3.5°) impact these results.