Aims. The primary aim of this study is to assess the survival of the uncemented hydroxyapatite (HA) coated Trident II acetabular component as part of a hybrid total hip arthroplasty (THA) using a cemented Exeter stem. The secondary aims are to assess the complications, joint-specific function, health-related quality of life, and radiological signs of loosening of the acetabular component. Methods. A single-centre, prospective cohort study of 125 implants will be undertaken. Patients undergoing hybrid THA at the study centre will be recruited. Inclusion criteria are patients suitable for the use of the uncemented acetabular component, aged 18 to 75 years, willing and able to comply with the study protocol, and provide informed consent. Exclusion criteria includes patients not meeting study inclusion criteria, inadequate bone stock to support fixation of the prosthesis, a BMI > 40 kg/m. 2. , or THA performed for pain relief in those with severely restricted mobility. Results. Implant survival, complications, functional outcomes and radiological assessment up to ten years following index THA (one, two, five, seven, and ten years) will be performed. Functional assessment will include the Oxford Hip Score, Forgotten Joint Score, 12-Item Short Form Health Survey, EuroQol five-dimension health questionnaire, and pain and patient satisfaction. Radiological assessment with assess for acetabula lucent lines, lysis, and loosening according to DeLee and Charnley zones. Conclusion. This study is part of a stepwise introduction of a new device to orthopaedic practice, and careful monitoring of implants should be carried out as part of the Beyond Compliance principles. The results of this study will provide functional, radiological, and survival data to either support the ongoing use of the HA acetabulum or highlight potential limitations of this new implant before wide adoption. Cite this article: Bone Jt Open 2023;4(10):782–790

Aims. After failed acetabular fractures, total hip arthroplasty (THA) is a challenging procedure and considered the gold standard treatment. The complexity of the procedure depends on the fracture pattern and the initial fracture management. This study’s primary aim was to evaluate patient-reported outcome measures (PROMs) for patients who underwent delayed uncemented acetabular THA after acetabular fractures. The secondary aims were to assess the radiological outcome and the incidence of the associated complications in those patients. Methods. A total of 40 patients underwent cementless acetabular THA following failed treatment of acetabular fractures. The postoperative clinical and radiological outcomes were evaluated for all the cohort. Results. The median (interquartile range (IQR)) Oxford Hip Score (OHS) improved significantly from 9.5 (7 to 11.5), (95% confidence interval (CI) (8 to 10.6)) to 40 (39 to 44), (95% CI (40 to 43)) postoperatively at the latest follow-up (p < 0.001). It was worth noting that the initial acetabular fracture type (simple vs complex), previous acetabular treatment (ORIF vs conservative), fracture union, and restoration of anatomical centre of rotation (COR) did not affect the final OHS. The reconstructed centre of rotation (COR) was restored in 29 (72.5%) patients. The mean abduction angle in whom acetabular fractures were managed conservatively was statistically significantly higher than the surgically treated patients 42.6° (SD 7.4) vs 38° (SD 5.6)) (p = 0.032). We did not have any case of acetabular or femoral loosening at the time of the last follow-up. We had two patients with successful two-stage revision for infection with overall eight-year survival rate was 95.2% (95% CI 86.6% to 100%) with revision for any reason at a median (IQR) duration of follow-up 50 months (16 to 87) months following THA. Conclusion. Delayed cementless acetabular THA in patients with previous failed acetabular fracture treatments produces good clinical outcomes (PROMS) with excellent survivorship, despite the technically demanding nature of the procedure. The initial fracture treatment does not influence the outcome of delayed THA. In selected cases of acetabular fractures (either nondisplaced or with secondary congruency), the initial nonoperative treatment neither resulted in large acetabular defects nor required additional acetabular reconstruction at the time of THA. Cite this article: Bone Jt Open 2021;2(12):1067–1074

Aims

The aim of this study was to evaluate the survival of a collarless, straight, hydroxyapatite-coated femoral stem in total hip arthroplasty (THA) at a minimum follow-up of 20 years.

Joint registries suggest a downward trend in the use of uncemented Total Knee Replacements (TKR) since 2003, largely related to reports of early failures of uncemented tibial and patella components. Advancements in uncemented design such as trabecular metal may improve outcomes, but there is a scarcity of high-quality data from randomised trials. 319 patients <75 years of age were randomised to either cemented or uncemented TKR implanted using computer navigation. Patellae were resurfaced in all patients. Patient outcome scores, re-operations and radiographic analysis of radiolucent lines were compared. Two year follow up was available for 287 patients (144 cemented vs 143 uncemented). There was no difference in operative time between groups, 73.7 v 71.1 mins (p= 0.08). There were no statistical differences in outcome scores at 2 years, Oxford knee score 42.5 vs 41.8 (p=0.35), International Knee Society 84.6 vs 84.0 (p=0.76), Forgotten Joint Score 66.7 vs 66.4 (p=0.91). There were two revisions, both for infection one in each group (0.33%). 13 cemented and 8 uncemented knees underwent re-operation, the majority of these being manipulation under anaesthetic (85.7%), with no difference (8.3% vs 5.3%, 95% CI -2.81% to 8.89%, p = 0.31). No difference was found in radiographic analysis at 2 years, 1 lucent line was seen in the cemented group and 3 in the uncemented group (0.67% v 2.09%, 95%CI -4.1% to 1.24%, p = 0.29). We found no difference in clinical or radiographic outcomes between cemented and uncemented TKR including routine patella resurfacing at two years. Early results suggest there is no difference between cemented and uncemented TKR at 2 years with reference to survivorship, patient outcomes and radiological parameters

Periprosthetic femur fracture (PFF) is a major complication following total hip arthroplasty (THA) that carries significant morbidity, mortality, and economic burden. Currently, uncemented stems are highly preferred in primary THA, but have been associated with higher risk of PFF compared to cemented stems. The use of collared stems in uncemented primary THA has shown promise in reducing PFF rates postoperatively. This retrospective study included 2,294 uncemented primary THAs using the posterior approach performed by two attending surgeons from January 2016 to December 2022. Both surgeons switched from a collarless femoral stem design to a collared design in May 2020. Data was collected regarding stem design, frequency of PFF, and requirement for revision surgery. Periprosthetic fractures were identified and confirmed using medical records and/or radiographic imaging. Fracture rates and percentages between collared and collarless stems were then analyzed. A Fisher's Exact Test was performed to determine if there was a significant association between collared and collarless stem use on PFF rates. A total of 2,294 uncemented primary THAs performed by 2 surgeons were eligible for analysis. 903 (39.4%) patients received a collared stem, and 1,391 (60.6%) patients received a collarless stem. In total, 14 (0.6%) PFFs occurred over the study period. There was 1 fracture (0.1%) out of 903 collared stems, and 13 fractures (0.9%) out of 1,391 collarless stems (p = 0.012). Collared stems were associated with a significant decrease in PFF rate when compared to collarless stems in uncemented primary THA. Future studies are encouraged to continue to investigate PFF and other complication rates with the use of a collared stem design

Our objective was to examine revision rates and patient reported outcome scores (PROMS) for cemented and uncemented primary total knee joint replacement (TKJR) at six months, one year and five years post-operatively. Patients and Methods: This matched cohort study involved secondary analyses of data collected as part of a large prospective observational study monitoring outcomes following knee replacement in Christchurch, New Zealand. Cemented and uncemented TKJR participants (n = 1526) were matched on age (± 5 years), sex and body mass index (BMI). From this larger sample, PROMS data, Oxford Knee Score and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), out to five years post-operatively were analysed for a matched subset of participants (n = 252). The average age of participants was 67.9 years (SD 9.4, range 38-94). There were no differences between cemented and uncemented cohorts on the basis of age, sex, BMI or comorbidities, revision rates or PROMS outcomes. Cemented procedures had greater skin to skin times than uncemented procedures (p < 0.01). Unadjusted outcomes comparing risk for revision across the two participant cohorts did not significantly differ. Overall rates for revision were low (cemented 3.2% v uncemented 2.7%, p=0.70). Propensity adjusted associations between baseline characteristics (age, sex, BMI, comorbidity, baseline Oxford and baseline WOMAC scores) also revealed no differences in risk for revision at any post-operative timepoint. In this large multi-surgeon matched cohort study there were no significant differences in functional outcomes or revision rates, when outcomes following modern cemented and uncemented TKJR were compared out to 5-year follow up. Based on our findings, uncemented TKJR is predictable irrespective of patient's age, BMI or gender

Source of the study: University of Auckland, Auckland, New Zealand. Unicompartmental knee arthroplasty (UKA) is effective for patients with isolated compartment osteoarthritis, however the procedure has higher revision rates. Long-term survivorship and accurate characterisation of revision reasons are limited by a lack of long-term data and standardised revision definitions. We aimed to identify survivorship, risk factors and revision reasons in a large UKA cohort with up to 20 years follow-up. Patient, implant and revision details were recorded through clinical and radiological review for 2,137 consecutive patients undergoing primary medial UKA across Auckland, Canterbury, Counties Manukau and Waitematā DHB between 2000 and 2017. Revision reasons were determined from review of clinical, laboratory, and radiological records for each patient using a standardised protocol. To ensure complete follow-up data was cross-referenced with the New Zealand Joint Registry to identify patients undergoing subsequent revision outside the hospitals. Implant survival, revision risk and revision reasons were analysed using Cox proportional-hazards and competing risk analyses. Implant survivorship at 15 years was comparable for cemented fixed-bearing (cemFB; 91%) and uncemented mobile-bearing (uncemMB; 91%), but lower for cemented mobile-bearing (cemMB; 80%) implants. There was higher incidence of aseptic loosening with cemented implants (3–4% vs. 0.4% uncemented, p<0.01), osteoarthritis (OA) progression with cemMB implants (9% vs. 3% cemFB/uncemMB; p<0.05) and bearing dislocations with uncemMB implants (3% vs. 2% cemMB, p=0.02). Compared with the oldest patients (≥75 years), there was a nearly two-fold increase in risk for those aged 55–64 (hazard ratio 1.9; confidence interval 1.1-3.3, p=0.03). No association was found with gender, BMI or ASA. Cemented mobile-bearing implants and younger age were linked to lower implant survivorship. These were associated with disease progression and bearing dislocations. The use of cemented fixed-bearing and uncemented mobile-bearing designs have superior comparable long-term survivorship

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

Periprosthetic fractures (PPF) of the femur following total hip arthroplasty represent a significant complication with a rising incidence. The commonest subtype is Vancouver B2 type, for which revision to a long uncemented tapered fluted stem is a widely accepted management. In this study we compare this procedure to the less commonly performed cement-in-cement revision. All patients undergoing surgical intervention for a Vancouver B2 femoral PPF in a cemented stem from 2008 – 2018 were identified. We collated patient age, gender, ASA score, BMI, operative time, blood transfusion requirement, change in haemoglobin (Hb) level, length of hospital stay and last Oxford Hip Score (OHS). Radiographic analysis was performed to assess time to fracture union and leg length discrepancy. Complications and survivorship of implant and patients were recorded. 43 uncemented and 29 cement-in-cement revisions were identified. There was no difference in patient demographics between groups. A significantly shorter operative time was found in the cement-in-cement group, but there was no difference in transfusion requirement, Hb change, or length of hospital stay. OHS was comparable between groups. A non-significant increase in overall complication rates was found in the revision uncemented group, with a significantly higher dislocation rate. Time of union was comparable and there were no non-unions in the cement-in-cement group. A greater degree of stem subsidence was found in the uncemented group. There was no difference in any revision surgery required in either group. Three patients in the uncemented group died in the perioperative period, compared to none in the cement-in-cement group. With appropriate patient selection, both cement-in-cement and long uncemented tapered stem revision represent appropriate treatment options for Vancouver B2 fractures

Introduction. Revision total knee arthroplasty (TKA) is becoming increasingly common in the United States as the population ages and larger numbers of primary TKA are performed in younger individuals. Cemented or uncemented tibial stems are frequently used in revision cases. Decreased clinical outcomes and patient satisfaction have been described for revision TKA. This study aims to determine if the presence of overall pain and tibial pain at the end of the stem differs between cemented and uncemented tibial stems in revision TKA. Methods. This was a retrospective cohort study comparing patients who underwent revision TKA utilizing cemented or uncemented tibial stems in a 15-year period at a single institution with at least two-year follow-up. Exclusion criteria included age under 18, isolated revisions of the femoral component or polyethylene exchanges, lack of preoperative or postoperative imaging, insufficient operative or implant records available for electronic chart review, revision procedures performed at outside facilities, patients who were deceased at the time of survey administration, refusal to participate in the study, and failure to return the mailed survey or respond to a telephone follow-up questionnaire. Radiographic analysis included calculation of the percentage of the tibial canal filled with the implant, as well as measurement of the diameter of the tibial stem. Radiographs were also reviewed for evidence of cavitary defects, pedestal formation, radiolucent lines, and periprosthetic fractures. Mailed surveys addressing overall pain, tibial pain, and satisfaction were analyzed using Fisher's exact test and the independent sample t-test. Logistic regression was used to adjust for age, gender, and preoperative bone loss. Results. A total of 110 patients were included (63 cemented and 47 uncemented stems). No statistically significant differences in stem length, operative side, or indications for revision were found. The uncemented group had a significantly higher percent canal fill (p < 0.0001). Tibial pain at the end of the stem was present in 25.3% of cemented stems and 25.5% of uncemented stems (p = 1.00). There was a trend towards more overall pain in the uncemented cohort, but this did not reach statistical significance. Only 74.6% of cemented patients and 78.7% of uncemented patients were satisfied following revision TKA (p = 0.66). Conclusion. The data supports our hypothesis that there are no differences in end-of-stem pain or overall pain between cemented and uncemented tibial stems in revision TKA. High rates of dissatisfaction were noted in both cohorts postoperatively, consistent with previous literature. Patient factors likely play a large role in the presence of postoperative pain. These factors should be further evaluated in future studies in an effort to reduce pain and improve patient satisfaction

Background. In recent years, ‘Get It Right First Time (GIRFT)’ have advocated cemented replacements in femoral part of Total hip arthroplasty (THA) especially in older patients. However, many studies were unable to show any difference in outcomes and although cemented prostheses may be associated with better short-term pain outcomes there is no clear advantage in the longer term. It is not clear when and why to do cemented instead of cementless. Aim. To assess differences in patient reported outcomes in uncemented THAs based on patient demographics in order to decide when cementless THA can be done safely. Method. Prospective data collection of consecutive 1079 uncemented THAs performed for 954 patients in single trust between 2010 and 2020. Oxford Hip Score (OHS) and complications were analysed against demographic variables (age, sex, BMI, ASA) and prosthesis features (femoral and acetabular size, offset and acetabular screws). Results. The mean pre-operative OHS was 14.6 which improved to 39.0 at 1 year follow up (P Value=0.000). There was no statistically significant difference between OHS outcome in patients aged over 70 versus younger groups. With a small number of revisable complications increase with age from 50s upwards. Male patients’ OHS score was on average 2.4 points higher than women. Men, however were 2.9 times more likely to experience fractures and high offset hips were 2.5 times more likely to experience dislocations. DAIR, intraoperative calcar fractures, post-operative fractures and dislocations were not associated with worse OHS. Patients with increased BMI had worse pre and post-operative hip functions yet, there was a significant multivariate association between increased BMI and increased improvement in OHS from pre-op to 1 year in women aged 55–80 and men under the age of 60. Femoral stem size increases with age but decreases in male patients over 80. There was no difference found in OHS between bilateral hip replacements and unilateral, nor was there any change found with laterality side of the replacement. Conclusions. This study suggests that ageing >70 is not associated with poorer outcomes despite small number of revisable complication rates that increase with age from 50 upwards. Men had marginally higher average OHS than women At 1 year. Higher BMI or ASA scores are associated with worse pre-operative hips and worse final outcome score. Despite this, the Delta OHS increases with increased BMI shown in the 55–80 year old female patients and male patients under 60. Key Words: THR, Uncemented, Oxford hip score, outcome

Aims. “Get It Right First Time” (GIRFT) and NHS England’s Best Practice Tariff (BPT) have published directives advising that patients over the ages of 65 (GIRFT) and 69 years (BPT) receiving total hip arthroplasty (THA) should receive cemented implants and have brought in financial penalties if this policy is not observed. Despite this, worldwide, uncemented component use has increased, a situation described as a ‘paradox’. GIRFT and BPT do, however, acknowledge more data are required to support this edict with current policies based on the National Joint Registry survivorship and implant costs. Methods. This study compares THA outcomes for over 1,000 uncemented Corail/Pinnacle constructs used in all age groups/patient frailty, under one surgeon, with identical pre- and postoperative pathways over a nine-year period with mean follow-up of five years and two months (range: nine months to nine years and nine months). Implant information, survivorship, and regular postoperative Oxford Hip Scores (OHS) were collected and two comparisons undertaken: a comparison of those aged over 65 years with those 65 and under and a second comparison of those aged 70 years and over with those aged under 70. Results. Overall revision rate was 1.3% (13/1,004). A greater number of revisions were undertaken in those aged over 65 years, but numbers were small and did not reach significance. The majority of revisions were implant-independent. Single component analysis revealed a 99.9% and 99.6% survival for the uncemented cup and femoral component, respectively. Mean patient-reported outcome measures (PROMs) improvement for all ages outperformed the national PROMs and a significantly greater proportion of those aged over 65/69 years reached and maintained a meaningful improvement in their OHS earlier than their younger counterparts (p < 0.05/0.01 respectively). Conclusion. This study confirms that this uncemented THA system can be used safely and effectively in patient groups aged over 65 years and those over 69 years, with low complication and revision rates. Cite this article: Bone Jt Open 2021;2(5):293–300

Aim: The objective of this study was to compare the initial stability of an uncemented curved long stem femoral component (ABR, Zimmer, Warsaw Indiana) implanted using conventional broaching to an uncemented ABR implanted as a revision using morselized compacted allograft to fill a circumferential proximal bone defect. Materials and Methods: Primary: Eight fresh frozen human femurs were implanted with correctly sized ABR stems without cement using standard surgical instruments and 1mm distal overreaming. The implant was loaded cyclically at 3 hz on a MTS servohdraulic materials test frame in a direction representing the peak force of the stance phase of the gait (2.5 X body weight). A 3-dimensional motion measurement device with six linear variable transformers measure the relative motion between the bone and the prosthesis with an accuracy of 0.5μm. The contruct was loaded in ten cycle increments until the component was seated and then recoverable motion was recorded over a further ten loading cycles. Revision: In the revision case bone loss was modelled by removing all the cancellous bone from the proximal femur with 1mm distal overreaming. Morselized bone graft was impacted into the defect using specially prepared smooth tamps shaped to the geometry of the ABR stem. The original prosthesis was then reimplanted without the use of cement. The seating and testing cycles were repeated. Primary and revision vectors were compared using a paired students t – test. Results: There was no statistically significant difference in the magnitude of the resultant vector of the 3 translational components of the micro motion between the two methods of implantation (p=0.19). Conclusions: Initial stability of a cementless femoral implant is a requirement for bone ingrowth. The use of compacted morsellized allograft in a revision Total Hip Arthroplasty with a proximal circumferential defect can provide a stable bed for the implantation of an uncemented femoral component. The revised implant using the compacted allograft method was initially as stable as the primary implantation. This technique would be particularly applicable when the surgeon would like to avoid the use of cement in a revision setting. The use of this method for uncemented revision Total Hip Arthroplasty should be studied further in a clinical setting before it is advocated for widespread use

We present the results of a prospective longitudinal follow-up study of Dual X-ray Absorptiometry (DXA) measurements of the evolution of bone mineral density (BMD) of acetabulum and femur in 86 patients who underwent total hip arthroplasty (THA). A standard uncemented cup and intra-operatively manufactured stem prosthesis was used in all patients. Stem fixation was determided by the bone quality Thirthy patients received cementless and 56 patients received cemented stem prosthesis. Post-operative DXA scans were obtained in peri-prosthetic bone at 10 days, 6 weeks, 3, 6 and 12 months after THA. Peri-prosthetic BMD values in the proximal femur were obtained in the 7 Gruen zones. In the acetabulum a 4 region of interest model (ROI) was used. Bimodal significant femoral BMD changes are found in all Gruen zones except for zone 1 of the cemented group where an immediate recovery is observed. The recovery mostly starts after 6 months of follow-up and the highest remodelling is found in the calcar region reaching even values of −16% at 6 months but no statistical significance was observed between the two groups. Significant linear losses (p< 0.0001) are observed in the pelvis region independent of type of fixation except the opposite change (p< 0.01) in the inferior region observing an immediate recovery in the uncemented group. We compared the impact of a cemented stem with a non cemented stem on the bone remodelling of the cup and found that there was a correlation between the type of fixation and the mode of remodelling at the acetabular level. This suggest that a parameter such as the flexibility my have an influence on the bone remodelling at the acetabulum level. The pattern of bone remodelling observed on the different Gruen zones reflects the local load transfer to peri-prosthetic bone

Uncemented total hip arthroplasty (THA) implants have become the standard for younger patients on account of increased implant survivorship and multiple other advantages. Nevertheless, uncemented THA remains controversial in elderly patients. The evidence base for this is limited, as previous studies have compared octogenarians to a younger control group. The aim of this prospective cohort study is to evaluate the outcome of octogenarian patients undergoing uncemented THA with a control group of similarly aged patients undergoing hybrid THA with a minimum 5 years follow up. Clinical outcomes including intra and postoperative complications, blood transfusion, revision rate and mortality were recorded. Radiological analysis of pre and postoperative radiograph assessed bone quality, implant fixation and any subsequent loosening. 143 patients, (mean age 86.2 yrs.) were enrolled in the study. 76 patients underwent uncemented THA and 67 underwent hybrid THA. The uncemented cohort had fewer intraoperative and postoperative complications. The uncemented cohort also had a lower transfusion rate (p=0.002). Mean hospital stay (p=0.27) was comparable between the 2 groups. Two patients underwent revision surgery in either cohort. Our study demonstrates uncemented THA is safe for the octogenarian patient and we recommend that age should be not be a barrier of choice of implant. However intraoperative assessment of bone quality should guide surgeon to the optimum decision regarding uncemented and hybrid implant

Introduction. Gram-negative prosthetic joint infections (GN-PJI) present unique challenges in management due to their distinct pathogenesis of biofilm formation on implant surfaces. The purpose of this study is to establish a clinically representative GN-PJI model that can reliably recapitulate biofilm formation on titanium implant surface in vivo. We hypothesized that biofilm formation on an implant surface will affect its ability to osseointegrate. Methods. The model was developed using 3D-printed titanium hip implants, to replace the femoral head of male Sprague-Dawley rats. GN-PJI was induced using two bioluminescent Pseudomonas aeruginosa strains: a reference strain (PA14-lux) and a mutant biofilm-defective strain (ΔflgK-lux). Infection was monitored in real-time using the in vivo imaging system (IVIS) and Magnetic Resonance Imaging (MRI). Bacterial loads on implant surface and in periprosthetic tissues were quantified utilizing viable-colony-count. Field-emission scanning-electron-microscopy of the explanted implants was used to visualize the biofilm formation at the bone-implant-interface. The implant stability, as an outcome, was directly assessed by quantifying the osseointegration in vitro using microCT scan, and indirectly assessed by identifying the gait pattern changes using DigiGait. TM. system in vivo. Results. Localized infection was established within the hip joint and was followed by IVIS in real-time. There was a quantitative and qualitative difference in the bacterial load and biofilm formation between PA14-lux and ΔflgK-lux. This difference in the ability to persist in the model between the two strains was reflected in the gait pattern and implant osseointegration. Conclusions. We developed a novel uncemented hip hemiarthroplasty, GN-PJI rat model. To date, the proposed in vivo biofilm-based model is the most clinically representative for GN-PJI since animals can bear weight on the implant and poor osseointegration correlates with biofilm formation. In addition, localized PJI was detected by various modalities. Clinical Relevance. The proposed in vivo GN-PJI model will allow for more reliable testing of novel biofilm-targeting therapeutics

Preventing infections in joint replacements is a major ongoing challenge, with limited effective clinical technologies currently available for uncemented knee and hip prostheses. This research aims to develop a coating for titanium implants, consisting of a supported lipid bilayer (SLB) encapsulating an antimicrobial agent. The SLB will be robustly tethered to the titanium using self-assembled monolayers (SAMs) of octadecylphosphonic acid (ODPA). The chosen antimicrobial is Novobiocin, a coumarin-derived antibiotic known to be effective against resistant strains of Staphylococcus aureus. ODPA SAMs were deposited on TiO. 2. -coated quartz crystal microbalance (QCM) sensors using two environmentally friendly non-polar solvents (anisole and cyclopentyl methyl ether, CPME), two concentrations of ODPA (0.5mM and 1mM) and two processing temperatures (21°C and 60°C). QCM, water contact angle measurements, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and temperature-programmed desorption mass spectrometry (TPD-MS) were used to characterise the ODPA SAM. A SLB with encapsulated Novobiocin was subsequently developed on the surface of the ODPA SAM using fluorescent lipids and a solvent assisted method. The prototype implant surface was tested for antimicrobial activity against S. aureus. A well-ordered, uniform ODPA SAM was rapidly formed using 0.5 mM ODPA in CPME at 21°C during 10 min, as confirmed by high Sauerbrey mass (≍285-290 ng/cm. 2. ), high atomic percentage phosphorus (detected using XPS) and high water contact angles (117.6±2.5°). QCM measurements combined with fluorescence microscopy provided evidence of complete planar lipid bilayer formation on the titanium surface using a solvent assisted method. Incorporation of Novobiocin into the SLB resulted in reduced attachment and viability of S. aureus. Key parameters were established for the rapid, robust and uniform formation of an ODPA SAM on titanium (solvent, temperature and concentration). This allowed the successful formation of an antimicrobial SLB, which demonstrated potential for reducing attachment and viability of pathogens associated with joint replacement infections

Gram-negative prosthetic joint infections (GN-PJI) present unique challenges in management due to their distinct pathogenesis of biofilm formation on implant surfaces. To date, there are no animal models that can fully recapitulate how a biofilm is challenged in vivo in the setting of GN-PJI. The purpose of this study is to establish a clinically representative GN-PJI in vivo model that can reliably depict biofilm formation on titanium implant surface. We hypothesized that the biofilm formation on the implant surface would affect the ability of the implant to be osseointegrated. The model was developed using a 3D-printed, medical-grade titanium (Ti-6Al-4V), monoblock, cementless hemiarthroplasty hip implant. This implant was used to replace the femoral head of a Sprague-Dawley rat using a posterior surgical approach. To induce PJI, two bioluminescent Pseudomonas aeruginosa (PA) strains were utilized: a reference strain (PA14-lux) and a mutant strain that is defective in biofilm formation (DflgK-lux). PJI development and biofilm formation was quantitatively assessed in vivo using the in vivo imaging system (IVIS), and in vitro using the viable colony count of the bacterial load on implant surface. Magnetic Resonance Imaging (MRI) was acquired to assess the involvement of periprosthetic tissue in vivo, and the field emission scanning electron microscopy (FE-SEM) of the explanted implants was used to visualize the biofilm formation at the bone-implant interface. The implant stability, as an outcome, was directly assessed by quantifying the osseointegration using microCT scans of the extracted femurs with retained implants in vitro, and indirectly assessed by identifying the gait pattern changes using DigiGaitTM system in vivo. A localized prosthetic infection was reliably established within the hip joint and was followed by IVIS in real-time. There was a quantitative and qualitative difference in the bacterial load and biofilm formation between PA14 and DflgK. This difference in the ability to persist in the model between the two strains was reflected on the gait pattern and implant osseointegration. We developed a novel uncemented hip hemiarthroplasty GN-PJI rat model. This model is clinically representative since animals can bear weight on the implant. PJI was detected by various modalities. In addition, biofilm formation correlated with implant function and stability. In conclusion, the proposed in vivo GN-PJI model will allow for more reliable testing of novel biofilm-targeting therapetics

Controversy persists over whether cemented or uncemented fixation is more effective in reducing revision and mortality risks following primary total hip arthroplasty (THA). Despite a shift towards uncemented THA in Europe, Australia, and the US, no consensus exists on superior outcomes. This ambiguity in evidence from randomized controlled trials (RCTs) and observational studies necessitates advanced research methodologies to derive more definitive conclusions. This study investigates the causal impact of THA fixation type on 2-year and 5-year revision rates, along with 90-day mortality, utilizing a regression discontinuity (RD) design in scenarios where fixation choice is guided by patient age. Employing data from the Dutch Arthroplasty Register, we conducted a cohort study on primary THAs for osteoarthritis from 2007 to 2019. A “fuzzy” RD design was executed to compute the Local Average Treatment Effect for subjects around the age-based selection threshold for fixation type. The main outcome of interest was the revision rate at 2 years post-operation. Analysis for the 2-year revision endpoint, covering any cause, included 2,344 females and 1,671 males across 5 hospitals each, with no significant variation in revision rates observed. For the 5-year mark, 1,058 females in 3 hospitals and 214 males in 1 hospital were examined, similarly showing no significant differences. Mortality within 90 days post-operation was also investigated in 5 female and 7 male cohorts, with 2,180 and 2,145 surgeries respectively, yielding no substantial disparities. In conclusion, the RD analysis revealed no notable differences in revision rates at 2 and 5 years or in early mortality based on the fixation method used in THA. These outcomes suggest that the age-based preference for THA fixation may not influence the revision or mortality risk, underscoring the value of RD design in deriving causal insights from observational data

Aims. To report early (two-year) postoperative findings from a randomized controlled trial (RCT) investigating disease-specific quality of life (QOL), clinical, patient-reported, and radiological outcomes in patients undergoing a total shoulder arthroplasty (TSA) with a second-generation uncemented trabecular metal (TM) glenoid versus a cemented polyethylene glenoid (POLY) component. Methods. Five fellowship-trained surgeons from three centres participated. Patients aged between 18 and 79 years with a primary diagnosis of glenohumeral osteoarthritis were screened for eligibility. Patients were randomized intraoperatively to either a TM or POLY glenoid component. Study intervals were: baseline, six weeks, six-, 12-, and 24 months postoperatively. The primary outcome was the Western Ontario Osteoarthritis Shoulder QOL score. Radiological images were reviewed for metal debris. Mixed effects repeated measures analysis of variance for within and between group comparisons were performed. Results. A total of 93 patients were randomized (46 TM; 47 POLY). No significant or clinically important differences were found with patient-reported outcomes at 24-month follow-up. Regarding the glenoid components, there were no complications or revision surgeries in either group. Grade 1 metal debris was observed in three (6.5%) patients with TM glenoids at 24 months but outcomes were not negatively impacted. Conclusion. Early results from this RCT showed no differences in disease-specific QOL, radiographs, complication rates, or shoulder function between uncemented second-generation TM and cemented POLY glenoids at 24 months postoperatively. Revision surgeries and reoperations were reported in both groups, but none attributed to glenoid implant failure. At 24 months postoperatively, Grade 1 metal debris was found in 6.5% of patients with a TM glenoid but did not negatively influence patient-reported outcomes. Longer-term follow-up is needed and is underway. Cite this article: Bone Jt Open 2021;2(9):728–736