Aim. Prosthetic joint infections pose a major clinical challenge. Developing novel material surface technologies for orthopedic implants that prevent bacterial adhesion and biofilm formation is essential. Antimicrobial coatings applicable to articulating implant surfaces are limited, due to the articulation mechanics inducing wear, coating degradation, and toxic particle release. Noble metals are known for their antimicrobial activity and high mechanical strength and could be a viable coating alternative for orthopaedic implants [1]. In this study, the potential of thin platinum-based metal alloy coatings was developed, characterized, and tested on cytotoxicity and antibacterial properties. Method. Three platinum-based metal alloy coatings were sputter-coated on medical-grade polished titanium discs. The coatings were characterized using optical topography and scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS). Ion release was measured using inductively coupled plasma optical emission spectrometry (ICP-OES). Cytotoxicity was tested according to ISO10993-5 using mouse fibroblasts (cell lines L929 and 3T3). Antibacterial surface activity, bacterial adhesion, bacterial proliferation, and biofilm formation were tested with gram-positive Staphylococcus aureus ATCC 25923 and gram-negative Escherichia coli ATCC 25922. Colony forming unit (CFU) counts, live-dead fluorescence staining, and SEM-EDS images were used to assess antibacterial activity. Results. Three different platinum-based metal alloys consisting of platinum-iridium, platinum-copper, and platinum-zirconium. The coatings were found 80 nm thick, smooth (roughness average < 60 nm), and non-toxic. The platinum-copper coating showed a CFU reduction larger than one logarithm in adherent bacteria compared to uncoated titanium. The other coatings showed a smaller reduction. This data was confirmed by SEM and live-dead fluorescence images, and accordingly, ICP-OES measurements showed low levels of metal ion release from the coatings. Conclusions. The platinum-copper coating showed low anti-adhesion properties, even with extremely low metal ions released. These platinum-based metal alloy coatings cannot be classified as antimicrobial yet. Further optimization of the coating composition to induce a higher ion release based on the galvanic principle is required and copper looks most promising as the antimicrobial compound of choice. Acknowledgments. This publication is supported by the DARTBAC project (with project number NWA.1292.19.354) of the research program NWA-ORC which is (partly) financed by the Dutch Research Council (NWO); and the AMBITION project (with project number NSP20–1-302), co-funded by the PPP Allowance made available by Health-Holland, Top Sector Life Sciences & Health to ReumaNederland

Aim. Debridement and implant retention (DAIR) is a valuable option for treating periprosthetic joint infection (PJI), provided that the criteria of the Infectious Diseases Society of America guidelines are fulfilled. The inflammation caused by infection and the surgical impact of DAIR may influence implant stability. In this study, we investigated the sequelae of DAIR on implant survival after total hip arthroplasty (THA). Method. THAs from our database implanted between 1984 and 2016 were included in a retrospective double-cohort study. THAs were exposed (DAIR cohort) or not exposed to DAIR (control cohort). The control cohort comprised patients matched 3:1 to the DAIR cohort. The outcome—implant failure over time—was evaluated for (i) revision for any reason, (ii) aseptic loosening of any component, and (iii) radiographic evidence of loosening. Results. Fifty-seven THAs (56 patients) were included in the DAIR cohort and 170 THAs (168 patients) in the control cohort. The mean follow-up periods in the DAIR and control cohorts were 6.1 (SD 4.7) and 7.8 (SD 5.5) years, respectively. During follow-up, 20 (36%) patients in the DAIR cohort and 54 (32%) in the control cohort died after a mean of 4.1 (SD 4.7) and 7.2 (SD 5.4) years, respectively. Revision for any reason was performed in 9 (16%) DAIR THAs and 10 (6%) control THAs (p = 0.03) and for aseptic loosening of any component in 5 (9%) DAIR THAs and 8 (5%, p = 0.32) control THAs, respectively. Radiological analysis included 56 DAIR THAs and 168 control THAs. Two (4%) stems and 2 (4%) cups in the DAIR cohort and 7 (4%) and 1 (0.6%) in the control cohort, respectively, demonstrated radiological signs of failure (p = 1). Conclusions. THAs exposed to DAIR were revised for any reason more frequently than were THAs in the control cohort. The difference in revisions for aseptic loosening was not statistically significant. There was no statistically significant difference in radiographic evidence of loosening of any component between cohorts

Background. Recent studies indicate the benefits of total hip arthroplasty (THA) by using femoral neck-preserving short-stem implants (March et al 1999). These benefits rely on the preservation of native hip structure and improved physiological loading. However, further investigation is needed to compare the outcome of these implants versus the conventional neck-sacrificing stems particularly assessed by patient-reported outcomes (PROs). In this study, we have investigated the differences in PROs between a neck-sacrificing stem design and neck-preserving short stem design (MiniHip, Corin Inc.). We hypothesized higher PROs outcome in patients who received treatment by using neck-preserving implants. Methods. In this study, we retrospectively analyzed the pre and post-operative PROs of patients receiving THA treatment by using neck-sacrificing implant (n=90, age 57±7.9 years) and a matched (BMI, age) cohort group of neck-preserving patients (n=105, age 55.16±9.88 years). Hip disability and Osteoarthritis Outcome Scores (HOOS) were using with the follow-up of similar follow up of 412.76 ± 206.98 days (neck sacrificing implant) and 454.63 ± 226.99 days (Neck-Preserving). Multivariate analysis of variance and Mann-Whitney tests were conducted for statistical analyses. Holm-Bonferroni adjusted for multiple comparisons was used with initial significance level of 0.05. Results. Both implants resulted in significant improvement of HOOS Subscores (p<0.001). There was a significant effect of time- surgery interaction (p=0.02). Follow-up HOOS subscores analysis indicated that patients who were treated with neck- preserving stems reported significantly higher Symptoms (p<0.001), Pain (p<0.001), ADL (p=0.011), Sports and Recreation (p=0.011), & QOL (p=0.007) subscores. Conclusion. This study aimed to investigate the short term to medium term outcome of neck-preserving implants. The superior outcome of neck-preserving femoral stems could be a result of more natural physiological loading in femoral cavity and higher retention of bone tissue in femoral neck area. However, further studies are needed to investigate the longer-term outcome of these implants

Problem. The identification of unknown orthopaedic implants is a crucial step in the pre-operative planning for revision joint arthroplasty. Compatibility of implant components and instrumentation for implant removal is specific based on the manufacturer and model of the implant. The inability to identify an implant correctly can lead to increased case complexity, procedure time, procedure cost and bone loss for the patient. The number of revision joint arthroplasty cases worldwide and the number implants available on the market are growing rapidly, leading to greater difficulty in identifying unknown implants. Solution. The solution is a machine-learning based mobile platform which allows for instant identification of the manufacturer and model of any implant based only on the x-ray image. As more surgeons and implant representatives use the platform, the model should continue to improve in accuracy and number of implants recognized until the algorithm reaches its theoretical maximum of 99% accuracy. Market. Multiple organizations have created small libraries of implant images to assist surgeons with manual identification of unknown implants based on the x-ray, however no automated implant identification system exists to date. One of the most financially successful implant identification tools on the market is a textbook of hip implants which sells for a per unit cost of $200. Several free web-based resources also act as libraries for the manual identification of a limited number of arthroplasty implants. A number of academic and private organizations are working on the development of an automated system for implant identification, however none are available to the public. Product. Implant Identifier is mobile application which uses machine-learning to instantly detect the model and manufacturer of any common arthroplasty implant, based only on x-ray. The beta version offers a large library of implants for manual identification and is currently available for free download on iOS and Android. Its purpose is to further develop the model to its maximal theoretical accuracy, prior to official release. The beta version of the application currently has over 15,000 registered users worldwide and has the largest publicly available arthroplasty library available on the market. Over 200,000 implant images have been submitted by users to date. Timescales. The product was initially released in the form of a closed beta which became available to invited guests around 18 months ago. The current version is an open beta which can be downloaded and used by any individual. It was released roughly 12 months ago. The final rendition of the application will allow for free manual identification using the implant library, as well as subscription-based automated implant identification. The implementation, testing and release of this final subscription product is projected to be completed by Q3 2022. Funding. A small number of early investors have funded the initial research and development of the beta product; however, another round of investment will be beneficial in the final evolution of the product. This additional investment round will allow for completion of development of the identification algorithm, product dissemination, customer support, and lasting sustainability of the venture

Introduction. Early complication post total knee replacement reported to be higher in obese patient in general. Also the outcome of cruciate retaining and PS knee has been fully discussed before and there was no major difference in the outcomes for all the patients overall regardless of their weight. However, the purpose of this paper is to find out if the CR knee has superiority over PS knee in terms of clinical and functional outcomes and if early complication postTKR such as fracture and instability is more common in PS implant than in CR knee. This is a retrospective study comparing two groups of obese patients. The first using PS implant and the other using CR implant. These two groups were matched for age, body mass and severity of deformity. Materials & Methods. At our institution we have been using Persona implant which has the option of using PS insert or a CR. The decision to proceed with CR or PS mainly depends on the availability of the implant and also the ability to well balance the knee in patients. In most patients we try to proceed with CR implant. However, the flow of implant sometime sometimes limit us from using CR or the imbalance in the ligament force us to process with PS implant. We have reviewed a chart of over 200 patients in each group of obese patient they were done within the last three years. All cases had a minimum follow up of 6 months. Those groups were matched for body mass, age and severity of deformity. After matching the groups we documented Knee Society Score (KSS), Knee Society Function Score (KSFS), blood loss, post – operative pain and complications. All surgeries were performed by the same surgeon. Results. Our study showed that the clinical scores (KSS) in both groups were very close while significant differences were observed in functional scores (KSFS) for the CR knee. We had 8 cases of per-prosthetic fracture in the PS group and one in the CR implant. We had 4 revisions in the PS group for instability and MCL insufficiency and non in the CR implant. Infection, wound complication, blood loss, and patient satisfaction were same in both groups. Discussion. This study suggests a significant difference in functional outcomes, especially walking, stair climbing and the use of walking aids, between CR and PS that favors CR implant which may be related to the CR knee retaining proprioception and ligaments tension with balance. In addition, PS knee have more varus-valgus and mid-flexion laxity than CR knee throughout the range of motion which appear clearly in obese patient. On the other hand, the study clearly shows that the decrease incidence of peri-prosthetic fracture in the CR implant which could be easily explained by the fact that a good cortical bone is resected in order to make room for the PS spine. Also, the fact that resecting the posterior cruciate ligament might cause more stress on the implant versus the CR. Instability also were more common in the PS group. We believe this has to do with the fact that the PCL serve as a secondary constraint to the MCL. The presence of the PCL help maintain the stability in case of incidental injury to the MCL during surgery which was reported to be higher in obese patients. Conclusion. There is clear advantage of improving the outcomes or knee scores and decreasing the early postoperative complications in obese patient using CR knee and we strongly recommend using CR implant in obese patients in order to restore functionality faster and reduce the incidence of peri-prosthetic fracture and the revision for instability

Massive irreparable rotator cuff tears often lead to superior migration of the humeral head, which can markedly impair glenohumeral kinematics and function. Although treatments currently exist for treating such pathology, no clear choice exists for the middle-aged patient demographic. Therefore, a metallic subacromial implant was developed for the purpose of restoring normal glenohumeral kinematics and function. The objective of this study was to determine this implant's ability in restoring normal humeral head position. It was hypothesized that (1) the implant would restore near normal humeral head position and (2) the implant shape could be optimized to improve restoration of the normal humeral head position. A titanium implant was designed and 3D printed. It consisted of four design variables that varied in both implant thickness (5mm and 8mm) and curvature of the humeral articulating surface (high constraint and low constraint. To assess these different designs, these implants were sequentially assessed in a cadaver-based biomechanical testing protocol. Eight cadaver specimens (64 ± 13 years old) were loaded at 0, 30, and 60 degrees of glenohumeral abduction using a previously developed shoulder simulator. An 80N load was equally distributed across all three deltoid heads while a 10N load was applied to each rotator cuff muscle. Testing states included a fully intact rotator cuff state, a posterosuperior massive rotator cuff tear state (cuff deficient state), and the four implant designs. An optical tracking system (Northern Digital, Ontario, Canada) was used to record the translation of the humeral head relative to the glenoid in both superior-inferior and anterior-posterior directions. Superior-Inferior Translation. The creation of a posterosuperior massive rotator cuff tear resulted in significant superior translation of the humeral head relative to the intact cuff state (P=0.016). No significant differences were observed between each implant design and the intact cuff state as all implants decreased the superior migration of the humeral head that was observed in the cuff deficient state. On average, the 5mm low and high constraint implant models were most effective at restoring normal humeral head position to that of the intact cuff state (-1.3 ± 2.0mm, P=0.223; and −1.5 ± 2.3mm, P=0.928 respectively). Anterior-Posterior Translation. No significant differences were observed across all test states for anterior-posterior translation of the humeral head. The cuff deficient on average resulted in posterior translation of the humeral head, however, this was not statistically significant (P=0.128). Both low and high constraint implant designs were found to be most effective at restoring humeral head position to that of the intact cuff state, on average resulting in a small anterior offset (5mm high constraint: 2.0 ± 4.7mm, P=1.000; 8mm high constraint: 1.6 ± 4.9mm, P=1.000). The 5mm high constraint implant was most effective in restoring normal humeral head position in both the superior-inferior and anterior-posterior directions. The results from this study suggest the implant may be an effective treatment for restoring normal glenohumeral kinematics and function in patients with massive irreparable rotator cuff tears. Future studies are needed to address the mechanical efficiency related to arm abduction which is a significant issue related to patient outcomes

Aim. Implant infections caused by Staphylococcus aureus are difficult to treat due to biofilm formation, which complicates surgical and antibiotic treatment. Herewith we introduce an alternative approach using monoclonal antibodies (mAbs) targeting S. aureus and provide the biodistribution and specificity in a mouse implant infection model. Methods. 4497-IgG1targeting S. aureus Wall Teichoic Acid was labeled to Indium-111 using “CHXA” as a chelator. SPECT-CT scans were performed at 24, 72 and 120 hours after administration in Balb/cAnNCrl mice with a subcutaneous implant pre-colonized with biofilm of S. aureus. Biodistribution over the various organs of this labelled antibody was visualized and quantified using SPECT-CT imaging and compared to uptake at the target tissue with implant infection. Results. Uptake of the . 111. In-4497 mAbs (half-life 59 hours) at the infected implant gradually increased from 8.34%ID/g at 24 hours to 9.22%ID/g at 120 hours. Uptake at the heart/blood pool decreased over time from 11.60 to 7.58%ID/g whereas the uptake in other organs decreased from 7.26 to less than 4.66%ID/g at 120 hours. Conclusion. 111. In-4497 mAbs was found to specifically detect S. aureus and its biofilm with excellent and prolonged accumulation at the colonized implant site. Therefore, it holds great promise as a drug delivery system for diagnostic and bactericidal treatment of biofilm. However, high activity in the blood pool must be considered as it could pose a risk to healthy tissue

Background. Total Hip Arthroplasty (THA) has long been the standard treatment for cases in which non-surgical alternatives have failed to improve pain and function in hip osteoarthritis (OA) patients. Outcomes from THA have improved over time with better surgical techniques and improved implant designs. While conventional neck-sacrificing implants have been associated with favorable outcomes, there is evidence to suggest biomechanical advantages of newer, femoral neck-preserving short-stem implants, including the Corin MiniHip. However, there is a still a gap of knowledge regarding the potential benefits of the MiniHip stem over conventional neck-sacrificing stems in regards to patient-reported outcomes (PROs). In this study, we investigated the differences between a neck-sacrificing stem design and neck-preserving short-stem design (MiniHip, Corin Inc.) arthroplasty concerning PROs, and considering the known features of the short stem design, we hypothesized that MiniHip THA would be associated with improved PROs in comparison to a neck-sacrificing implant system. We further sought to investigate gender effects related to MiniHip or conventional stem surgery. Methods. Neck-sacrificing implant patients (n=90, age 57±7.9 years, female=58, male=32) and a matched (matching criteria: follow-up period, BMI, age) cohort group of MiniHip patients (n=105, age 55.16±9.88 years, female: 25, male: 80) reported both pre-operative and post-operative Hip disability and Osteoarthritis Outcome Scores (HOOS) at a minimum interval of 6 months post-operatively and up to three years postoperatively. We applied MANCOVA analysis to compare patient-reported outcome subscores from each group using follow-up period as a covariate and employing gender as an additional grouping factor to evaluate gender effects. Statistical significance was set at α=0.05 and Bonferroni corrections were applied to account for multiple comparisons. Results. There was a main effect of time, showing that all HOOS subscores of both groups increased significantly after surgery (p<0.001). There was a main effect of surgery for subscores Symptoms (p=0.038), ADL (p=0.046), and Sports and Recreation (p=0.039). There was a gender effect only for the subscore Symptoms (p=0.007). There were significant time by surgery interactions for HOOS subscores Symptoms (p=0.002), Pain (p=.009), Sports and Recreation (p=0.004), and QOL (p<0.001) subscores. We also observed a significant time by gender interaction effect for all HOOS subscores (p<0.001). Discussion. The interaction effects regarding most HOOS subscores and surgery/implant type indicate an advantage of MiniHip surgery regarding post-operative reported outcomes. The observed results may be due to previously described improved physiological loading and native hip structure preservation with neck-preserving short-stem designs. While longer-term studies are required for further investigation, evidence suggests the MiniHip may provide a significant benefit to primary THA patients. The additional gender/time interaction effect observed in our study highlights the necessity to consider potential sex differences regarding both the potential/expected improvement in PROs from THA and the requirement to account for such differences when designing osteoarthritis outcome studies based on PROs

Background and aim. Implant-associated osteomyelitis is one of the most feared complications following orthopedic surgery. Although the risk is low it is crucial to achieve adequate antibiotic concentrations proximate to the implant for a sufficient amount of time to protect the implant surface and ensure tissue integration. The aim of this study was to assess steady-state piperacillin concentrations in the proximity of an orthopedic implant inserted in cancellous bone. Method. Six female pigs received an intravenous bolus infusion of 4 g/0.5 g piperacillin/tazobactam over 30 min every 6 h. Steady state was assumed achieved in the third dosing interval (12–18 h). Microdialysis catheters were placed in a cannulated screw in the proximal tibial cancellous bone, in cancellous bone next to the screw, and in cancellous bone on the contralateral tibia. Dialysates were collected from time 12 to 18 h and plasma samples were collected as reference. Results. Time above the minimal inhibitory concentration (fT>MIC) was evaluated for MIC of 8 (low target) and 16 μg/mL (high target). For the low piperacillin target (8 μg/mL), comparable mean fT>MIC across all the investigated compartments (mean range: 54–74%) was found. For the high target (16 μg/mL), fT>MIC was shorter inside the cannulated screw (mean: 16%) than in the cancellous bone next to the screw and plasma (mean range: 49–54%), and similar between the two cancellous bone compartments. Conclusions. To reach more aggressive piperacillin fT>MIC targets in relation to the implant, alternative dosing regimens such as continuous infusion may be considered

Aim. The treatment of fracture-related infections (FRI) focuses on obtaining fracture healing and eradicating infection to prevent osteomyelitis. Treatment guidelines include removal, exchange, or retention of the implants used according to the stability of the fracture and the time from the infection. Infection of a fracture in the process of healing with a stable fixation may be treated with implant retention, debridement, and antibiotics. Nonetheless, the retention of an intramedullary nail is a potential risk factor for failure, and it is recommended to exchange or remove the nail. This surgical approach implies additional life-threatening risks in elderly fragile hip fracture patients. Our study aimed to analyze the results of implant retention for the treatment of infected nails in elderly hip fracture patients. Methods. Our retrospective analysis included patients 65 years of age or older with an acute fracture-related infection treated with implant retention from 2012 to 2020 in 6 Spanish hospitals with a minimum 1-year follow-up. Patients that required open reduction during the initial fracture surgery were excluded. Variables included in our analysis were patient demographics, type of fracture, date of FRI diagnosis, causative microorganism, and outcome. Treatment success was defined as fracture healing with infection eradication without the need for further hospitalization. Results. A total of 48 patients were identified. Eight patients with open reduction were excluded and 11 did not complete a 1-year follow-up. Out of the 29 remaining patients, the mean age was 81.5 years, with a 21:9, female to male ratio. FRI was diagnosed between 10 and 48 days after initial surgery (mean 26 days). Treatment success was achieved in 24 patients (82.7%). Failure was objectivated in polymicrobial infections or infections caused by microorganisms resistant to antibiofilm antibiotics. Seven patients required more than one debridement with a success rate of 57%. Twelve patients had an infection diagnosed after 21 days from the initial surgery and implant retention was successful in all of them. Conclusion. Our results suggest implant retention is a valid therapeutic approach for fracture-related infection in elderly hip fracture patients treated by closed reduction and intramedullary nailing

Aim. A novel anti-infective biopolymer implant coating was developed to prevent bacterial biofilm formation and allow on-demand burst release of anti-infective silver (Ag) into the surrounding of the implant at any time after surgery via focused high-energy extracorporeal shock waves (fhESW). Method. A semi-crystalline Poly-L-lactic acid (PLLA) was loaded with homogeneously dissolved silver (Ag) applied onto Ti6Al4V discs. A fibroblast WST-1 assay was performed to ensure adequate biocompatibility of the Ag concentration at 6%. The prevention of early biofilm formation was investigated in a biofilm model with Staphylococcus epidermidis RP62A after incubation for 24 hours via quantitative bacteriology. In addition, the effect of released Ag after fhESW (Storz DUOLITH SD1: 4000 impulses, 1,24 mJ/mm. 2. , 3Hz, 162J) was assessed via optical density of bacterial cultures (Escherichia coli TG1, Staphylococcus epidermidis RP62A, Staphylococcus aureus 6850) and compared to an established electroplated silver coating. The amount of released Ag after the application of different intensities of fhESW was measured and compared to a control group without fhESW via graphite furnace atomic absorption spectrometry (GF-AAS), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Results. The coating with 6% Ag reduced Staphylococcus epidermidis biofilm formation by 99.7% (mean±SD: 2.1×10^5 ± 3,9×10^5 CFU/µL) compared to uncoated controls (6.8×10^7 ± 4.9×10^7 CFU/µL); (p=0.0001). After applying fhESW the commercially available electroplated silver coating did not prevent the growth of all tested bacterial strains. Bacterial growth is delayed with 4% Ag and completely inhibited with 6% Ag in the novel coating, except for a small increase of S. aureus after 17 hours. SEM and EDS confirmed a local disruption of the coating after fhESW. Conclusions. This novel anti-infective implant coating has the potential to prevent bacterial biofilm formation. The on-demand burst release of silver via fhESW could be an adjunctive in the treatment of implant related infection and is of particular interest in the concept of single stage revision surgery

Accurate implant size estimation for internal fixation of long bone fractures can reduce intra-operative errors, operative time and radiation exposure. With the advent of pre-packed sterile implants, the exponential increase in the number of internal fixation devices and the lack of standard templates for them on PACS systems, templating has become increasingly difficult. This often results in the opening up of wrong implants leading to increased costs both in terms of increased operative time and additional implants. We describe a technique to determine implant size preoperatively using sterile implant boxes. Post anaesthesia and positioning, the pre packed implant box of approximate size is placed over the limb across the fracture site. An X-ray is then taken using the C-arm. In case of a plate, the number of holes desired on either side of the fracture, the shape of the implant and planned placement of screws are seen. Different implant boxes with the contained implant are placed and once the most appropriate implant for the particular fracture is reached, the box is opened and implant is kept ready for insertion. This technique has been found to be accurate, easy, reproducible and effective for estimating the implant size thereby decreasing the chances of opening wrong implants and saving the intra operative time substantially

Dual mobility (DM) is an established bearing option in Total Hip Arthroplasty (THA). The traditional mono-block DM designs have limited ability for additional fixation, whereas the modular DM designs allow additional screw fixation but limit internal diameter and have the potential to generate metal debris. We report the early results of a CoCrMo alloy mono-block implant manufactured by additive technology with a highly porous ingrowth surface to enhance primary fixation and osseointegration. Prospective follow-up of the Duplex. TM. implant first inserted in March 2016 enrolled into Beyond Compliance (BC). Primary outcome measure was all-cause revision and secondary outcomes dislocation, peri-prosthetic fracture (PPF) and Oxford Hip Score (OHS). Patients were risk stratified and all considered to be high risk for instability. Complications were identified via hospital records, clinical coding linkage using national database and via BC website. 159 implants in 154 patients with a mean age 74.0 years and a maximum F/U of 7 years. Survivorship for all-cause revision 99.4% (95% CI 96.2–99.8). One femoral only revision. Mean gain in OHS 27.4. Dislocation rate 0.6% with a single event. Patients with a cemented Polished taper stem (PTS) had a Type B PPF rate of 2.1% requiring revision/fixation. Compared to conventional THA this cohort was significantly older (74.0 vs 68.3 years), more co-morbidity (ASA 3 46.5% vs 14.4%) and more non-OA indications (32.4% vs 8.5%). Every patient had at least one risk factor for falling and >50% of cohort had 4 or more risk factors using NICE tool. We believe our results demonstrate that risk stratification successfully aids implant selection to prevent dislocation in high-risk patients. This novel design has provided excellent early results in a challenging cohort where individuals are very different to the “average” THA patient. NJR data on DM has reported an increase in revision for PPF. A “perfect storm” maybe created using DM in high-risk falls risk population. This re-enforces the need to consider all patient and implant factors when deciding bearing selection

Revision surgeries for orthopaedic infections are done in two stages – one surgery to implant an antibiotic spacer to clear the infection and another to install a permanent implant. A permanent porous implant, that can be loaded with antibiotics and allow for single-stage revision surgery, will benefit patients and save healthcare resources. Gyroid structures can be constructed with high porosity, without stress concentrations that can develop in other period porous structures [1] [2]. The purpose of this research is to compare the resulting bone and prosthesis stress distributions when porous versus solid stems are implanted into three proximal humeri with varying bone densities, using finite element models (FEM). Porous humeral stems were constructed in a gyroid structure at porosities of 60%, 70%, and 80% using computer-aided design (CAD) software. These CAD models were analyzed using FEM (Abaqus) to look at the stress distributions within the proximal humerus and the stem components with loads and boundary conditions representing the arm actively maintained at 120˚ of flexion. The stem was assumed to be made of titanium (Ti6Al4V). Three different bone densities were investigated, representing a healthy, an osteopenic, and an osteoporotic humerus, with an average bone shape created using a statistical shape and density model (SSDM) based on 75 cadaveric shoulders (57 males and 18 females, 73 12 years) [3]. The Young's moduli (E) of the cortical and trabecular bones were defined on an element-by-element basis, with a minimum allowable E of 15 MPa. The Von Mises stress distributions in the bone and the stems were compared between different stem scenarios for each bone density model. A preliminary analysis shows an increase in stress values at the proximal-lateral region of the humerus when using the porous stems compared to the solid stem, which becomes more prominent as bone density decreases. With the exception of a few mesh dependent singularities, all three porous stems show stress distributions below the fatigue strength of Ti-6Al-4V (410 MPa) for this loading scenario when employed in the osteopenic and osteoporotic humeri [4]. The 80% porosity stem had a single strut exceeding the fatigue strength when employed in the healthy bone. The results of this study indicate that the more compliant nature of the porous stem geometries may allow for better load transmission through the proximal humeral bone, better matching the stress distributions of the intact bone and possibly mitigating stress-shielding effects. Importantly, this study also indicates that these porous stems have adequate strength for long-term use, as none were predicted to have catastrophic failure under the physiologically-relevant loads. Although these results are limited to a single boney geometry, it is based on the average shape of 75 shoulders and different bone densities are considered. Future work could leverage the shape model for probabilistic models that could explore the effect of stem porosity across a broader population. The development of these models are instrumental in determining if these structures are a viable solution to combatting orthopaedic implant infections

Introduction. There is current debate concerning the most biomechanically advantageous knee implant systems, and there is also currently great interest in improving patient satisfaction after knee arthroplasty. Additionally, there is no consensus whether a posterior-stabilized (PS) total knee device is superior to a more congruent, cruciate-substituting, medially-stabilized device (MS). This study compared the clinical outcomes of two such devices. The primary hypothesis was that the clinical outcomes, and specifically the patient satisfaction as measured by the Forgotten Joint Score, would be better in the MS group. Methods. This prospective, randomized, blinded Level 1 study compared the outcomes of 100 patients who received a Medacta GMK PS device and 101 patients who received a Medacta GMK medially-stabilized Sphere device (Medacta Intl., Lugano, Switzerland). All patients undergoing elective primary total knee arthroplasty were eligible for participation. Institutional Review Board approval and informed consent from participants were obtained. The devices were implanted using an anatomic alignment/calipered- measured resection surgical approach. Clinical and radiographic assessments were performed preoperatively, 6 weeks, 6 months, and annually. Data were compared using T-test with a significance level of 0.05. Results. The minimum follow-up period is 2 years. There were no statistically significant differences in demographic characteristics and preoperative scores; tourniquet time was 7.24% longer for the PS group (40.28 min vs 37.56 min, P < .0086). Alignment was not different between the groups (preoperative or postoperative). There were significant differences between groups for the 1 year and 2 years postop Knee Society scores, Forgotten Joint Score, and ROM; in every case where there was a statistically significant difference, the results were better in the MS group. For example, the FJS was 65.72 in the MS group at 2 years, 54.33 in the PS group (p=0.02). The maximum active flexion at 2 years was 129.75º in the MS group, in the PS group it was 122.27º (p=0.03). Conclusion. The clinical outcomes of the MS group at 1 and 2 years, including the Forgotten Joint Score and flexion, were better statistically, and there was a statistically longer tourniquet time for the PS group. At the minimum 2-year follow-up, the results demonstrate superiority of the medially-stabilized device in terms of multiple clinical outcomes, including patient satisfaction as measured by the Forgotten Joint Score. These findings support the use of a medially-stabilized knee implant system, and support the conclusion that this design, in conjunction with an anatomic alignment, calipered-measured resection surgical technique, offers improved biomechanics and kinematics

Hip resurfacing arthroplasty (HRA) is a bone conserving alternative to total hip arthroplasty. We present the early 1 and 2-year clinical and radiographical follow-up of a novel ceramic-on-ceramic (CoC) HRA in a multi-centric Australian cohort. Patient undergoing HRA between September 2018 and April 2021 were prospectively included. Patient-reported outcome measures (PROMS) in the form of the Forgotten Joint Score (FJS), HOOS Jr, WOMAC, Oxford Hip Score (OHS) and UCLA Activity Score were collected preoperatively and at 1- and 2-years post-operation. Serial radiographs were assessed for migration, component alignment, evidence of osteolysis/loosening and heterotopic ossification formation. 209 patients were identified of which 106 reached 2-year follow-up. Of these, 187 completed PROMS at 1 year and 90 at 2 years. There was significant improvement in HOOS (p< 0.001) and OHS (p< 0.001) between the pre-operative, 1-year and 2-years outcomes. Patients also reported improved pain (p<0.001), function (p<0.001) and reduced stiffness (p<0.001) as measured by the WOMAC score. Patients had improved activity scores on the UCLA Active Score (p<0.001) with 53% reporting return to impact activity at 2 years. FJS at 1 and 2-years were not significantly different (p=0.38). There was no migration, osteolysis or loosening of any of the implants. The mean acetabular cup inclination angle was 41.3° and the femoral component shaft angle was 137°. No fractures were reported over the 2-year follow-up with only 1 patient reporting a sciatic nerve palsy. There was early return to impact activities in more than half our patients at 2 years with no early clinical or radiological complications related to the implant. Longer term follow-up with increased patient numbers are required to restore surgeon confidence in HRA and expand the use of this novel product. In conclusion, CoC resurfacing at 2-years post-operation demonstrate promising results with satisfactory outcomes in all recorded PROMS

Glenoid baseplate orientation in reverse shoulder arthroplasty (RSA) influences clinical outcomes, complications, and failure rates. Novel technologies have been produced to decrease performance heterogeneity of low and high-volume surgeons. This study aimed to determine novice and experienced shoulder surgeon's ability to accurately characterise glenoid component orientation in an intra-operative scenario. Glenoid baseplates were implanted in eight fresh frozen cadavers by novice surgical trainees. Glenoid baseplate version, inclination, augment rotation, and superior-inferior centre of rotation (COR) offset were then measured using in-person visual assessments by novice and experienced shoulder surgeons immediately after implantation. Glenoid orientation parameters were then measured using 3D CT scans with digitally reconstructed radiographs (DRRs) by two independent observers. Bland-Altman plots were produced to determine the accuracy of glenoid orientation using standard intraoperative assessment compared to postoperative 3D CT scan results. Visual assessment of glenoid baseplate orientation showed “poor” to “fair” correlation to 3D CT DRR measurements for both novice and experienced surgeon groups for all measured parameters. There was a clinically relevant, large discrepancy between intra-operative visual assessments and 3D CT DRR measurements for all parameters. Errors in visual assessment of up to 19.2 degrees of inclination and 8mm supero-inferior COR offset occurred. Experienced surgeons had greater measurement error than novices for all measured parameters. Intra-operative measurement errors in glenoid placement may reach unacceptable clinical limits. Kinesthetic input during implantation likely improves orientation understanding and has implications for hands-on learning

Roentgen Stereophotogrammetric Analysis (RSA) is the gold standard for measuring implant micromotion thereby predicting implant loosening. Early migration has been associated with the risk of long-term clinical failure. We used RSA to assess the stability of the Australian designed cementless hip stem (Paragon TM) and now report our 5-year results. Fifty-three patients were prospectively and consecutively enrolled to receive a Paragon hip replacement. Tantalum beads were inserted into the bone as per RSA protocol and in the implant. RSA x-rays were taken at baseline 1–4 days post-surgery, at 6 weeks, 6 months, 12 months, 2 years, and 5 years. RSA was completed by an experienced, independent assessor. We reported the 2-year results on 46 hips (ANZJS 91 (3) March 2021 p398) and now present the 5-year results on 27 hips. From the 2-year cohort 5 patients had died, 8 patients were uncontactable, 1 patient was too unwell to attend, 5 patients had relocated too far away and declined. At 5 years the mean axial subsidence of the stem was 0.66mm (0.05 to 2.96); the mean rotation into retroversion was 0.49˚ (−0.78˚ to 2.09˚), rotation of the stem into valgus was −0.23˚ (−0.627˚ to 1.56˚). There was no detectable increase in subsidence or rotation between 6 weeks and 5 years. We compared our data to that published for the Corail cementless stem and a similar pattern of migration was noted, however greater rotational stability was achieved with the Paragon stem over a comparable follow-up period. The RSA results confirm that any minor motion of the Paragon cementless stem occurs in the first 6 weeks after which there is sustained stability for the next 5 years. The combination of a bi-planar wedge and transverse rectangular geometry provide excellent implant stability that is comparable to or better than other leading cementless stems

Lumbar fusion surgery is an established procedure for the treatment of several spinal pathologies. Despite numerous techniques and existing devices, common surgical trends in lumbar fusion surgery are scarcely investigated. The purpose of this Canada-based study was to provide a descriptive portrait of current surgeons’ practice and implant preferences in lumbar fusion surgery while comparing findings to similar investigations performed in the United Kingdom. Canadian Spine Society (CSS) members were sampled using an online questionnaire which was based on previous investigations performed in the United Kingdom. Fifteen questions addressed the various aspects of surgeons’ practice: fusion techniques, implant preferences, and bone grafting procedures. Responses were analyzed by means of descriptive statistics. Of 139 eligible CSS members, 41 spinal surgeons completed the survey (29.5%). The most common fusion approach was via transforaminal lumber interbody fusion (TLIF) with 87.8% performing at least one procedure in the previous year. In keeping with this, 24 surgeons (58.5%) had performed 11 to 50 cases in that time frame. Eighty-six percent had performed no lumbar artificial disc replacements over their last year of practice. There was clear consistency on the relevance of a patient specific management (73.2%) on the preferred fusion approach. The most preferred method was pedicle screw fixation (78%). The use of stand-alone cages was not supported by any respondents. With regards to the cage material, titanium cages were the most used (41.5%). Published clinical outcome data was the most important variable in dictating implant choice (87.8%). Cage thickness was considered the most important aspect of cage geometry and hyperlordotic cages were preferred at the lower lumbar levels. Autograft bone graft was most commonly preferred (61.0%). Amongst the synthetic options, DBX/DBM graft (64.1%) in injectable paste form (47.5%) was preferred. In conclusion, findings from this study are in partial agreement with previous work from the United Kingdom, but highlight the variance of practice within Canada and the need for large-scale clinical studies aimed to set specific guidelines for certain pathologies or patient categories

Multiple joint registries have reported better implant survival for patients aged >75 years undergoing total hip arthroplasty (THA) with cemented implant combinations when compared to hybrid or uncemented implant combinations. However, there is considerable variation within these broad implant categories, and it has therefore been suggested that specific implant combinations should be compared. We analysed the most common contemporary uncemented (Corail/Pinnacle), hybrid (Exeter V40/Trident) and cemented (Exeter V40/Exeter X3) implant combinations in the New Zealand Joint Registry (NZJR) for patients aged >75 years. All THAs performed using the selected implants in the NZJR for patients aged >75 years between 1999 and 2018 were included. Demographic data, implant type, and outcome data including implant survival, reason for revision, and post-operative Oxford Hip Scores were obtained from the NZJR, and detailed survival analyses were performed. Primary outcome was revision for any reason. Reason for revision, including femoral or acetabular failure, and time to revision were recorded. 5427 THAs were included. There were 1105 implantations in the uncemented implant combination group, 3040 in the hybrid implant combination group and 1282 in the cemented implant combination group. Patient reported outcomes were comparable across all groups. Revision rates were comparable between the cemented implant combination (0.31 revisions/100 component years) and the hybrid implant combination (0.40 revisions/100 component years) but were statistically significantly higher in the uncemented implant combination (0.80/100 component years). Femoral-sided revisions were significantly greater in the uncemented implant combination group. The cemented implant and hybrid implant combinations provide equivalent survival and functional outcomes in patients aged over 75 years. Caution is advised if considering use of the uncemented implant combination in this age group, predominantly due to a higher risk of femoral sided revisions. The authors recommend comparison of individual implants rather than broad categories of implants