Management of ankle arthritis in young patients is challenging. Although ankle arthrodesis gives consistent pain relief, it leads to loss of function and adjacent joint arthritis. Ankle joint distraction (AJD) has been shown to give good outcomes in adults with osteoarthritis or post-traumatic arthritis. The efficacy in children or young adults and those with juvenile idiopathic arthritis is less well evidenced. Clinical notes and radiographs of all patients (n=6) managed with AJD in one tertiary referral centre were retrospectively reviewed. Radiographs were taken pre-surgery, intra-operatively, 1 month following frame removal and at the last follow up, tibiotalar joint space was assessed using ImageJ software. Measurements were taken at the medial, middle and lateral talar dome using frame components as reference. Radiographic data for patients with a good clinical outcome was compared with those who did not. At time of surgery mean age was 16.1 years (12 – 25 years). Mean follow up was 3.4 years (1.5 – 5.9 years). Indications were juvenile idiopathic arthritis (4) post-traumatic (1) and post-infective arthritis (1). Three patients at last follow up had a good clinical outcome. Two patients required revision to arthrodesis (1.3 and 2.4 years following distraction). One patient had spontaneous fusion. One patient required oral antibiotics for pin site infection. Inter-observer reliability was 95%. Mean joint space was 1.17mm (SD = 0.87mm) pre-operatively which increased to 6.72mm (SD = 2.23mm) at the time of distraction and 2.09mm (SD = 1.14mm) at the time of removal. At one-year follow up, mean joint space was 1.96mm (SD = 1.97mm). Outcomes following AJD in this population are variable although significant benefits were demonstrated for 50% of the patients in this series. Radiographic joint space preoperatively did not appear to be associated with need for arthrodesis. Further research in larger groups of young patients is required

Arthritis is a common and debilitating disease and is associated with an increased fall risk. The purpose of this study was to examine the effect of impacted joint and limb on fall risk as measured by the margin of stability (MOS). There were 110 participants, including healthy controls (HC; n=30), ankle arthritis (AA; n=30), knee arthritis (KA; n=20) and hip arthritis (HA; n=30) patients. All protocols were Institutional Review Board approved and all participants signed informed consent. Participants walked approximately 6 meters at a self-selected pace. MOS was calculated in the foot coordinate system in the anterior/posterior (AP) and medial/lateral (ML) directions at heel strike. A one-way ANOVA was used to examine group effects (HC, AA, KA, HA) on gait speed. A two-way repeated measures ANOVA was used to examine the effects of limb (Non-Surgical, Surgical) and group on AP and ML MOS. HC had the fastest gait speed (1.40±0.24 m/s; p<0.001) when compared to AA (0.85±0.24 m/s), KA (0.94±0.22 m/s) and HA (1.05±0.22 m/s). HA participants had a greater gait speed compared to AA (p=0.004). AP MOS was greater in the surgical limb compared to the non-surgical limb for AA (p<0.001) and HA (p<0.001). AP MOS was smaller in HC compared to AA, KA, and HA, regardless of limb (p<0.030). AP MOS was similar between AA, KA, and HA for the non-surgical limb (p>0.194) and the surgical limb (p>0.096). ML MOS was greater in the surgical compared to non-surgical limb (p=0.003). ML MOS was smaller in KA participants compared to all other groups (p<0.001). Our results demonstrate stability during gait varies between limbs in arthritis patients, with a more conservative pattern for the surgical limb and suggest KA may be at an increased risk of falls with a smaller ML MOS

In an osteological collection of 3100 specimens, 70 were found with unilateral clavicular fractures which were matched with 70 randomly selected normal specimens. This formed the basis of a study of the incidence of arthritis of the acromioclavicular joint and the effect of clavicular fracture on the development of arthritis in the ipsilateral acromioclavicular joint. This was graded visually on a severity scale of 0 to 3. The incidence of moderate to severe arthritis of the acromioclavicular joint in normal specimens was 77% (100 specimens). In those with a clavicular fracture, 66 of 70 (94%) had arthritis of the acromioclavicular joint, compared to 63 of 70 (90%) on the non-injured contralateral side (p = 0.35). Clavicles with shortening of 15 mm or less had no difference in the incidence of arthritis compared to those with shortening greater than 15 mm (p = 0.25). The location of the fracture had no effect on the development of arthritis

Intra-articular injection is a common way to deliver biologics to joints, but their effectiveness is limited by rapid clearance from the joint space. This barrier can be overcome by genetically modifying cells within the joint such that they produce anti-arthritic gene products endogenously, thereby achieving sustained, therapeutic, intra-articular concentrations of the transgene products without re-dosing. A variety of non-viral and viral vectors have been subjected to preclinical testing to evaluate their suitability for delivering genes to joints. The first transfer of a gene to a human joint used an ex vivo protocol involving retrovirally transduced, autologous, synovial fibroblasts. Recent advances in vector technology allow in vivo delivery using adeno-associated virus (AAV). We have developed an AAV vector encoding the interleukin-1 receptor antagonist (AAV.IL-1Ra) for injection into joints with osteoarthritis (OA). It showed efficacy and safety in equine and rat models of OA, leading to a recently-completed, investigator-initiated, Phase I, dose-escalation clinical trial in 9 subjects with mid-stage OA of the knee (ClinicalTrials.gov Identifier: NCT02790723). Three cohorts of three subjects with mild to moderate OA in the index knee were injected intra-articularly under ultrasound guidance with a low (10e11 viral genomes) medium (10e12 viral genomes) or high (10e13 viral genomes) dose of AAV.IL-1Ra and followed for one year. The data confirm safety, with evidence of sustained intra-articular expression of IL-1Ra and a clinical response in certain subjects. Funding for a subsequent Phase Ib trial involving 50 subjects (ClinicalTrials.gov Identifier: NCT05835895), expected to start later this year, has been acquired. Progress in this area has stimulated commercial activity and there are now at least seven different companies developing gene therapies for OA and a number of clinical trials are in progress.

Acknowledgement: Clinical trial funded by US Department of Defense Clinical Trial Award W81XWH-16-1-0540.

We performed a systematic review to compare outcomes of cemented versus uncemented trapezio-metacarpal joint (TMCJ) replacement for treatment of base-of-thumb arthritis. We assessed improvements in pain and function, range of movement (ROM), strength, complications and need for revision surgery. A thorough literature search was performed. A total of 481 studies were identified from the literature search (179 Medline, 253 Embase, 27 CINAHL, 22 Cochrane). Of 43 relevant titles 28 were selected for full-text review after assessment of the abstracts. Duplicate studies were removed. 18 studies met inclusion criteria on full-text review. All studies were of level IV evidence. There were no randomised controlled trials or meta-analyses. The studies were critically appraised using a validated scoring system. Most studies reported good outcomes for pain and strength, and functional outcome was comparable for both groups. ROM was generally improved for both prosthetic types, however statistical calculation was lacking in many studies. Trapezial component loosening was the main problem for both cemented and uncemented prostheses, however radiological loosening did not necessarily correlate with implant failure. This systematic review has found that both cemented and uncemented replacements generally give good outcomes for the treatment of TMCJ arthritis, however young, male, patients with manual occupations and with disease in the dominant hand and patients with poor trapezial bone stock appear to be at higher risk for implant failure due to cup loosening. We recommend the construction of a joint registry to record implantation and revision rates

Preoperative planning for Total Hip Arthroplasty has been acknowledged as a vital step to facilitate a successful outcome. Templating ascertains the dimensions and positioning of the implants, minimizing both intraoperative and postoperative complications. The purpose of this study is to compare the accuracy of digital templating to acetate templating in the preoperative planning of Total Hip Arthroplasty.

Preoperative planning was performed on 40 consecutive patients (mean age = 70.5 years), undergoing Total Hip Arthroplasty. Digital templating was performed by the Hip fellow 1, using Orthoview software (Jacksonville, FL, USA) and recorded the sizes of the cup and stem for each of the 40 patients. Subsequently, the same 40 patients were templated by Hip fellow 2, with X-rays done with a lead marker of known size by the side of the femur, using, acetate templating method. Templating results were compared to the actual sizes of the implants used, as noted in operative notes. Templating scores for the acetabular cup were 40% (16/40) with digital templating and 50% (20/40) with acetate templating. The templating scores for stem were 28% (11/40) with digital templating and 90% (36/40) with acetate templating. The differences between templating and actual implant sizes were plotted in Bland–Altman plot. Acetate templating proved to be statistically, significantly more accurate than digital templating (p value= 0.0083).

Our results indicate that the traditional acetate method is solid and valid to use for preoperative planning. This method is accurate and offers a more affordable option for preoperative templating. Although the templated size is one, there is a tendency to increase cup size to use bigger heads, which is the recent National Joint Registries trend. We recommend that acetate templating should be used as the default option.

Patellofemoral osteoarthritis (PFOA) affects 32% men and 36% women over the age of 60years and is associated with anterior knee pain, stiffness, and poor mobility. Patellofemoral arthroplasty (PFA) is a bone-sparing treatment for isolated PFOA. This study set out to investigate the relationship between patient-related outcome measures (PROMs) and measurements obtained from gait analysis before and after PFA. There are currently no studies relating to gait analysis and PFA available in the literature

A prospective cohort study was conducted of ten patients known to have isolated PFOA who had undergone PFA compared to a gender and age matched control group. The patients were also asked to complete questionnaires (Oxford knee score (OKS), EQ-5D-5L) before surgery and one year after surgery. Gait analysis was done on an instrumented treadmill comparing Ground reaction force parameters between the control and pre and post-operative PFA patients

The average age 60 (49–69) years with a female to male ratio of 9:1. Patient and healthy subjects were matched for age and gender, with no significant difference in BMI. Post-op PFA improvement in gait seen in ground reaction force at 6.5km/h. Base support difference was statistically significant both on the flat P=0.0001 and uphill P=0.429 (5% inclination) and P=0.0062 (10% inclination). PROMS response rate was 70%(7/10) pre-operative and 60%(6/10) post-operative. EQ-5D-5L scores reflected patient health state was better post-operatively.

This study found that gait analysis provides an objective measure of functional gait and reflected by significant quality-of-life improvement of patients post PFA. Literature lacks studies relating to gait-analysis and PFA. Valuable information provided by this study highlights that PFA has a beneficial outcome reflected by PROMs and improvement in vertical ground reaction force and gait

Further research is needed to assess how care-providers may use gait-analysis as part of patient care plans for PFOA patients.

Introduction and Objective. Malunion after trauma can lead to coronal plane malalignment in the lower limb. The mechanical hypothesis suggests that this alters the load distribution in the knee joint and that that this increased load may predispose to compartmental arthritis. This is generally accepted in the orthopaedic community and serves as the basis guiding deformity correction after malunion as well as congenital or insidious onset malalignment. Much of the literature surrounding the contribution of lower limb alignment to arthritis comes from cohort studies of incident osteoarthritis. There has been a causation dilemma perpetuated in a number of studies - suggesting malalignment does not contribute to, but is instead a consequence of, compartmental arthritis. In this investigation the relationship between compartmental (medial or lateral) arthritis and coronal plane malalignment (varus or valgus) in patients with post traumatic unilateral limb deformity was examined. This represents a specific niche cohort of patients in which worsened compartmental knee arthritis after extra-articular injury must rationally be attributed to malalignment. Materials and Methods. The picture archiving system was searched to identify all 1160 long leg x ray films available at a major metropolitan trauma center over a 12-year period. Images were screened for inclusion and exclusion criteria, namely patients >10 years after traumatic long bone fracture without contralateral injury or arthroplasty to give 39 cases. Alignment was measured according to established surgical standards on long leg films by 3 independent reviewers, and arthritis scores Osteoarthritis Research Society International (OARSI) and Kellegren-Lawrence (KL) were recorded independently for each compartment of both knees. Malalignment was defined conservatively as mechanical axis deviation outside of 0–20 mm medial from centre of the knee, to give 27 patients. Comparison of mean compartmental arthritis score was performed for patients with varus and valgus malalignment, using Analysis of Variance and linear regression. Results. In knees with varus malalignment there was a greater mean arthritis score in the medial compartment compared to the contralateral knee, with OARSI scores 5.69 vs 3.86 (0.32, 3.35 95% CI; p<0.05) and KL 2.92 vs 1.92 (0.38, 1.62; p<0.005). There was a similar trend in valgus knees for the lateral compartment OARSI 2.98 vs 1.84 (CI −0.16, 2.42; p=0.1) and KL 1.76 vs 1.31 (CI −0.12, 1.01; p=0.17), but the evidence was not conclusive. OARSI arthritis score was significantly associated with absolute MAD (0.7/10mm MAD, p<0.0005) and Time (0.6/decade, p=0.01) in a linear regression model. Conclusions. Malalignment in the coronal plane is correlated with worsened arthritis scores in the medial compartment for varus deformity and may similarly result in worsened lateral compartment arthritis in valgus knees. These findings support the mechanical hypothesis that arthritis may be related to altered stress distribution at the knee, larger studies may provide further conclusive evidence

Introduction. The human wrist is a highly complex joint, offering extensive motion across various planes. This study investigates scapholunate ligament (SLL) injuries’ impact on wrist stability and arthritis risks using cadaveric experiments and the finite element (FE) method. It aims to validate experimental findings with FE analysis results. Method. The study utilized eight wrist specimens on a custom rig to investigate Scapho-Lunate dissociation. Contact pressure and flexion were measured using sensors. A CT-based 3D geometry reconstruction approach was used to create the geometries needed for the FE analysis. The study used the Friedman test with pairwise comparisons to assess if differences between testing conditions were statistically significant. Result. The study found significant variations in scaphoid and lunate bone movement based on ligament condition. Full tears increased scapholunate distance in the distal-proximal direction and decreased in the medial-lateral direction. Lunate angles shifted from flexion to extension with fully torn ligaments. Conversely, the scaphoid shifted significantly from extension to flexion with full tears. A proximal movement was observed in the distal-proximal direction in all groups, with significant differences in the partial tear group. Lateral deviation of the scaphoid and lunate occurred with ligament damage, being more pronounced in the partial tear group. All groups exhibited statistically significant movement in the volar direction, with the full tear group showing the least movement. Also, radiocarpal joint and finger contact pressure and contact area were studied. Whereas the differences in contact area were not significant, scapholunate ligament tears resulted in significantly decreased finger contact pressures. FEA confirmed these findings, showing notable peak radiocarpal contact pressure differences between intact and fully torn ligaments. Conclusion. Our study found that SLL damage alters wrist stability, potentially leading to early arthritis. The FEA model confirmed these findings, indicating the potential for the clinical use of computer models from CT scans for treatment planning

Introduction and Objective. Septic arthritis is an acute infective presentation of the joint calling for urgent intervention, thus making the differential diagnosis process difficult. An increase in temperature in the area containing the suspected septic arthritis is one of the clinically important findings. In this study, it was aimed to investigate whether or not the temperature changes obtained through thermal camera can be used as a new additional diagnostic tool in the differential diagnosis of septic arthritis. Materials and Methods. The study was approved by the local ethics committee as a prospective cohort. A total of 49 patients, 15 septic and 34 non-septic ones, both male and female ones from all ages admitted to the emergency room or evaluated with the consultation of another clinics who were also present with a pre-diagnosis of arthritis (septic or non-septic) in the knee (with complaints of redness, swelling, pain, effusion, increased temperature, edema, and inability to walk) were included in the study. The patients with non-joint inflammatory problems and a history of surgery in the same joint were excluded from the study. The temperature increase in the joint area with suspected septic arthritis was observed, and the difference in temperature changes of this suspicious area with the joint area of the contralateral extremity was compared after which the diagnosis of septic arthritis was confirmed by taking culture with routine intra-articular fluid aspiration, which is the gold standard for definitive diagnosis. Results. The mean age of the patients was 39.89 ± 27.65°C. A significant difference was found between the group with and without septit arthritis in terms of ASO, sedimentation, and leukocyte increase in the analysis of joint fluid (p <0.05). When the thermal measurements were compared, the mean temperature was 37.93°C in the septic group, while it was 36.79°C in the non-septic group, which showed a significant difference (p <0.000∗). The mean temperature difference in both joints was 3.40°C in the septic group, while 0.94°C in the non-septic group (p <0.000∗). While the mean temperature was 37.10°C in the group with septit arthritis, it was measured to be 35.89 °C in the group without (p <0.020). A very strong positive correlation was found between the difference between the mean temperatures of both groups and the values of the hottest and coldest temperature points (r = 0.960, r = 0.902). Conclusions. In the diagnosis of septic arthritis, a thermal imager can be used as a non-invasive diagnostic tool. With the help of this device, a quantitative value, in addition to palpation, can be given to the local temperature increase in the joint, which is an important finding in the clinic of septic arthritis. In future studies, specially designed thermal devices developed with special software for septic arthritis can be developed

Despite the clinical relevance of back pain and intervertebral disc herniation, the lack of reliable models has strained their molecular understanding. We characterized the lumbar spinal phenotype of C57BL/6 and SM/J mice during aging. Interestingly, old SM/J lumbar discs evidenced accelerated degeneration, associated with high rates of disc herniation. SM/J AF's and degenerative human's AF transcriptomic profiles showed altered immune cell, inflammation, and p53 pathways. Old SM/J mice presented increased neuronal markers in herniated discs, thicker subchondral bone, and higher sensitization to pain. Dorsal root ganglia transcriptomic studies and spinal cord analysis exhibited increased pain and neuroinflammatory markers associated with altered extracellular matrix regulation. Immune system single-cell and tissue level analysis showed distinctive T-cell and B-cell modulation and negative correlation between mechanical allodynia and INF-α, IL-1β, IL2, and IL4, respectively. This study underscores the multisystemic network behind back pain and highlights the role of genetic background and the immune system in disc herniation disease. Acknowledgments: This study is supported by grants from the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) R01AR055655, R01AR064733, R01AR074813 to MVR

Abstract. Background. The influence of diagnosis on outcomes after reverse shoulder arthroplasty (RSA) is not completely understood. The purpose of this study was to compare clinical outcomes of different pathologies. Methods. A total of 78 RSAs were performed for the following diagnoses: (1) rotator cuff tear arthropathy(RCA), (2) massive cuff tear(MCT) with osteoarthritis(OA), (3) MCT without OA, (4) arthritis, (5) acute proximal humerus fracture. Mean follow up 36 months (upto 5 years) Range of motion, Oxford Shoulder Score were obtained preoperatively and postoperatively. Results. Mean OSS was 30. The RCA, MCT-with-OA, MCT-without-OA, and arthritis groups all exhibited significant improvements in all outcome scores and in all planes of motion. After adjustment for age and compared with RCA, those with OA had significantly better abduction (P < .05), and those with fractures had significantly worse patient satisfaction (P < .05). Among male patients, those with MCTs without OA had significantly worse satisfaction (P < .05). Conclusion. RSA reliably provides improvement regardless of preoperative diagnosis. Although subtle differences exist between male and female patients, improvements in clinical outcome scores were apparent after RSA

Abstract. Objectives. Magnetic resonance imaging (MRI) is one of the most widely used investigations for knee pain as it provides detailed assessment of the bone and soft tissues. The aim of this study was to report the frequency of each diagnosis identified on MRI scans of the knee and explore the relationship between MRI results and onward treatment. Methods. Consecutive MRI reports from a large NHS trust performed in 2017 were included in this study. The hospital electronic system was consulted to identify whether a patient underwent x-ray prior to the MRI, attended an outpatient appointment or underwent surgery. Results. 4466 MRI knees were performed in 2017 with 71.2% requested in primary care and 28.1% requested in secondary care. The most common diagnosis was signs of arthritis (55.2%), followed by meniscal tears (42.8%) and ACL tears (8.3%). 49.4% of patients who had an MRI attended outpatients and 15.6% underwent surgery. The rate of knee surgery was significantly higher for patients who had their scans requested in secondary care (32.9% vs 8.9%, p < 0.001). Conclusion. The rate of surgical intervention following MRI is low and given these results it seems unlikely that the scan changes practice in most cases. The rate of surgery and outpatient follow up was significantly higher in scans requested by secondary care. We urge clinicians avoid wasteful use of MRI and recommend the use of plain radiography prior to MRI where arthritis may be present

Despite considerable legacy issues, Girdlestone's Resection Arthroplasty (GRA) remains a valuable tool in the armoury of the arthroplasty surgeon. When reserved for massive lysis in the context of extensive medical comorbidities which preclude staged or significant surgical interventions, and / or the presence of pelvic discontinuity, GRA as a salvage procedure can have satisfactory outcomes. These outcomes include infection control, pain control and post-op function. We describe a case series of 13 cases of GRA and comment of the indications, peri, and post-operative outcomes. We reviewed all cases of GRA performed in our unit during an 8 year period, reviewing the demographics, indications, and information pertaining to previous surgeries, and post op outcome for each. Satisfaction was based on a binary summation (happy/unhappy) of the patients’ sentiments at the post-operative outpatient consultations. 13 cases were reviewed. They had a mean age of 75. The most common indication was PJI, with 10 cases having this indication. The other three cases were performed for avascular necrosis, pelvic osteonecrosis secondary to radiation therapy and end stage arthritis on a background of profound learning disability in a non-ambulatory patient. The average number of previous operations was 5 (1-10). All 13 patients were still alive post girdlestone. 7 (54%) were satisfied, 6 were not. 3 patients were diabetic. 5 patients developed a sinus tract following surgery. With sufficient pre-op patient education, early intensive physiotherapy, and timely orthotic input, we feel this procedure remains an important and underrated and even compassionate option in the context of massive lysis and / or the presence of pelvic discontinuity / refractory PJI. GRA should be considered not a marker of failure but as a definitive procedure that gives predictability to patients and surgeon in challenging situations

Tendon injury is debilitating and recalcitrant. With limited knowledge of disease aitiology we have are lacking in effective treatments for this prevalent musculoskeletal complaint. This presentation will outline our findings over the past few years in which we have demonstrated the importance of the interfascicular matrix (IFM) niche in maintaining healthy tendon function and driving disease progression. 1,2. It will also continue to describe our progress in developing both in vivo and in vitro models to interrogate disease progression. We have developed and validated a rat Achilles tendon overload model, in order to explore the impact of loading on IFM and fascicle structure, and the resulting cell response. Data highlights that structural disruption and inflammatory response both initiate in the IFM region, and can be seen in the absence of demonstrable changes to animal gait, indicating a sub-injury response in the tendon which we hypothesis may drive increased matrix turnover and repair. 3. . We are now looking to interrogate the pathways driving this inflammatory behaviour in an organ-chip model, exploring the interplay between IFM cells and cells within fascicles. We have demonstrated phenotypic distinction of cells from the two niche environments, localized the progenitor phenotype to the IFM region and demonstrated significant mechanosensitivity in the IFM cell population. 4. We are currently building appropriate niche environments to maintain cell phenotype in our in vitro models, to explore the metabolic changes associated with disease progression. Acknowledgements: This body of work has received funding from: BBSRC (BB/K008412 /1); Versus Arthritis (project grant 20262); Horserace Betting Levy Board (T5); Dunhill Medical Charity (project grant RPGF1802\23); MRC (MR/T015462/1)

Introduction. Tibiocalcaneal arthrodesis with a retrograde intramedullary nail is an established procedure considered as a salvage in case of severe arthritis and deformity of the ankle and subtalar joints [1]. Recently, a significant development in hindfoot arthrodesis with plates has been indicated. Therefore, the aim of this study was to compare a plate specifically developed for arthrodesis of the hindfoot with an already established nail system [2]. Method. Sixteen paired human cadaveric lower legs with removed forefoot and cut at mid-tibia were assigned to two groups for tibiocalcaneal arthrodesis using either a hindfoot arthrodesis nail or an arthrodesis plate. The specimens were tested under progressively increasing cyclic loading in dorsiflexion and plantar flexion to failure, with monitoring via motion tracking. Initial stiffness was calculated together with range of motion in dorsiflexion and plantar flexion after 200, 400, 600, 800, and 1000 cycles. Cycles to failure were evaluated based on 5° dorsiflexion failure criterion. Result. Initial stiffness in dorsiflexion, plantar flexion, varus, valgus, internal rotation and external rotation did not differ significantly between the two arthrodesis techniques (p ≥ 0.118). Range of motion in dorsiflexion and plantar flexion increased significantly between 200 and 1000 cycles (p < 0.001) and remained not significantly different between the groups (p ≥ 0.120). Cycles to failure did not differ significantly between the two techniques (p = 0.764). Conclusion. From biomechanical point of view, both tested techniques for tibiocalcaneal arthrodesis appear to be applicable. However, clinical trials and other factors, such as extent of the deformity, choice of the approach and preference of the surgeon play the main role for implant choice. Acknowledgements. This study was performed with the assistance of the AO Foundation

Total knee and hip arthroplasty (TKA and THA) are the most commonly performed surgical procedures, the costs of which constitute a significant healthcare burden. Improving access to care for THA/TKA requires better efficiency. It is hypothesized that this may be possible through a two-stage approach that utilizes prediction of surgical time to enable optimization of operating room (OR) schedules. Data from 499,432 elective unilateral arthroplasty procedures, including 302,490 TKAs, and 196,942 THAs, performed from 2014-2019 was extracted from the American College of Surgeons (ACS) National Surgical and Quality Improvement (NSQIP) database. A deep multilayer perceptron model was trained to predict duration of surgery (DOS) based on pre-operative clinical and biochemical patient factors. A two-stage approach, utilizing predicted DOS from a held out “test” dataset, was utilized to inform the daily OR schedule. The objective function of the optimization was the total OR utilization, with a penalty for overtime. The scheduling problem and constraints were simulated based on a high-volume elective arthroplasty centre in Canada. This approach was compared to current patient scheduling based on mean procedure DOS. Approaches were compared by performing 1000 simulated OR schedules. The predict then optimize approach achieved an 18% increase in OR utilization over the mean regressor. The two-stage approach reduced overtime by 25-minutes per OR day, however it created a 7-minute increase in underutilization. Better objective value was seen in 85.1% of the simulations. With deep learning prediction and mathematical optimization of patient scheduling it is possible to improve overall OR utilization compared to typical scheduling practices. Maximizing utilization of existing healthcare resources can, in limited resource environments, improve patient's access to arthritis care by increasing patient throughput, reducing surgical wait times and in the immediate future, help clear the backlog associated with the COVID-19 pandemic

Tendon injuries occur frequently in athletes and the general population, with inferior healing leading to deposition of fibrotic scar tissue. New treatments are essential to limit fibrosis and enable tendon regeneration post-injury. In this study, we tested the hypothesis that rapamycin improves tendon repair and limits fibrosis by inhibiting the mTOR pathway. The left hindlimb of female adult Wistar rats was injured by needle puncture and animals were either given daily injections of rapamycin (2mg/kg) or vehicle. Animals were euthanized 1 week or 3 weeks post-injury (n=6/group). Left and right Achilles tendons were harvested, with the right limbs acting as controls. Tendon sections were stained with haematoxylin & eosin, and scored by 2 blinded scorers, assessing alterations in cellularity, cell morphology, vascularity, extracellular matrix (ECM) organization and peritendinous fibrosis. Immunohistochemistry was performed for the tendon pan-vascular marker CD146 and the autophagy marker LC3. Injury resulted in significantly altered ECM organization, cell morphology and cellularity in both rapamycin and vehicle-treated groups, but no alterations in vascularity compared to uninjured tendons. Rapamycin had a limited effect on tendon repair, with a significant reduction in peritendinous fibrosis 3 weeks after injury (p=0.028) but no change in cell morphology, cellularity or ECM organization compared to vehicle treated tendons at either 1 week or 3 weeks post injury. CD146 labelling was increased at the site of injury, but there was no apparent difference in CD146 or LC3 labelling in rapamycin and vehicle treated tendons. The decrease in peritendinous fibrosis post-injury observed in rapamycin treated tendons indicates rapamycin as a potential therapy for tendon adhesions. However, the lack of improvement of other morphological parameters in response to rapamycin treatment indicates that rapamycin is not an effective therapy for injuries to the tendon core. Acknowledgements: This study was funded by Versus Arthritis (22607)

Total knee arthroplasty (TKA) aims to alleviate pain and restore joint biomechanics to an equivalent degree to age-matched peers. Zimmer Biomet's Nexgen TKA was the most common implant in the UK between 2003 and 2016. This study compared the biomechanical outcomes of the Nexgen implant against a cohort of healthy older adults to determine whether knee biomechanics is restored post-TKA. Patients with a primary Nexgen TKA and healthy adults >55 years old with no musculoskeletal deficits or diagnosis of arthritis were recruited locally. Eligible participants attended one research appointment. Bilateral knee range of motion (RoM) was assessed with a goniometer. A motorised arthrometer (GENOUROB) was then used to quantify the anterior-posterior laxity of each knee. Finally, gait patterns were analysed on a treadmill. An 8-camera Vicon motion capture system generated the biomechanical model. Preliminary statistical analyses were performed in SPSS (α = 0.05; required sample size for ongoing study: n=21 per group). The patient cohort (n=21) was older and had a greater BMI than the comparative group (n=13). Patients also had significantly poorer RoM than healthy older adults. However, there were no inter-group differences in knee laxity, walking speed or cadence. Gait kinematics were comparable in the sagittal plane during stance phase. Peak knee flexion during swing phase was lower in the patient group, however (49.0° vs 41.1°). Preliminary results suggest that knee laxity and some spatiotemporal and kinematic parameters of gait are restored in Nexgen TKA patients. While knee RoM remains significantly poorer in the patient cohort, an average RoM of >110° was achieved. This suggests the implant provides sufficient RoM for most activities of daily living. Further improvements to knee kinematics may necessitate additional rehabilitation. Future recruitment drives will concentrate on adults over the age of 70 for improved inter-group comparability

Reorientating pelvic osteotomies are performed to improve femoral head coverage and secondary degenerative arthritis. A rectangular triple pelvic innominate osteotomy (3PIO) is performed in symptomatic cases. However, deciding optimal screw fixation type to avoid complications is questionable. Therefore, this study aimed to investigate the biomechanical behavior of two different acetabular screw configurations used for rectangular 3PIO osteosynthesis. It was hypothesized that bi-directional screw fixation would be biomechanically superior to mono-axial screw fixation technique. A rectangular 3PIO was performed in twelve right-side artificial Hemi-pelvises. Group 1 (G1) had two axial and one transversal screw in a bi-directional orientation. Group 2 (G2) had three screws in the axial direction through the iliac crest. Acetabular fragment was reoriented to 10.5° inclination in coronal plane, and 10.0° increased anteversion along axial plane. Specimens were biomechanically tested until failure under progressively increasing cyclic loading at 2Hz, starting at 50N peak compression, increasing 0.05N/cycle. Stiffness was calculated from machine data. Acetabular anteversion, inclination and medialization were evaluated from motion tracking data from 250-2500 at 250 cycle increments. Failure cycles and load were evaluated for 5° change in anteversion. Stiffness was higher in G1 (56.46±19.45N/mm) versus G2 (39.02±10.93N/mm) but not significantly, p=0.31. Acetabular fragment anteversion, inclination and medialization increased significantly each group (p≤0.02) and remained non-significantly different between the groups (p≥0.69). Cycles to failure and failure load were not significantly different between G1 (4406±882, 270.30±44.10N) and G2 (5059±682, 302.95±34.10N), p=0.78. From a biomechanical perspective, the present study demonstrates that a bi-directional screw orientation does not necessarily advantageous versus mono-axial alignment when the latter has all three screws evenly distributed over the osteotomy geometry. Moreover, the 3PIO fixation is susceptible to changes in anteversion, inclination and medialization of the acetabular fragment until the bone is healed. Therefore, cautious rehabilitation with partial weight-bearing is recommended