This study examined pre-operative measures to predict post-operative biomechanical outcomes in total knee arthroplasty (TKA) patients. Twenty-eight patients (female=12/male=16, age=63.6±6.9, BMI=29.9±7.4 kg/m2) with knee osteoarthritis scheduled to undergo TKA were included. All surgeries were performed by the same surgeon (GD) with a subvastus approach. Patients visited the gait lab within one-month prior to surgery and 12 months following surgery. At the gait lab, patients completed the knee injury and osteoarthritis outcome score (KOOS), a timed up and go (TUG), maximum knee flexion and extension strength evaluation, and a walking task. Variables of interest included the five KOOS sub-scores, TUG time, maximum knee flexion and extension strength normalized to body weight, walking speed, and peak knee biomechanics variables (flexion angle, abduction moment, power absorption). A Pearson's correlation was used to identify significantly correlated variables which were then inputted into a multiple regression. No assumption violations for the multiple regression existed for any variables. Pre-operative knee flexion and extension strength, TUG time, and age were used in the multiple regression. The multiple regression model statistically significantly predicted peak knee abduction moment, post-operative walking speed, and post-operative knee flexion strength. All four variables added statistically significantly to the prediction p<.05. Pre-operative KOOS values did not correlate with any biomechanical indicators of post-operative success. Age, pre-operative knee flexion and extension strength, and TUG times predicted peak knee abduction moment, which is associated with medial knee joint loading. These findings stress the importance of pre-surgery condition, as stronger individuals achieved better post-operative biomechanical outcomes. Additionally, younger patients had better outcomes, suggesting that surgeons should not delay surgery in younger patients. This delay in surgery may prevent patients from achieving optimal outcomes. Future studies should utilize a hierarchical multiple regression to identify which variables are most predictive

To investigate if the countermovement jump height differs between ACL injured and uninjured female adolescents and to explore kinematic differences between limbs. Additionally, the association between isometric knee extension strength and jump height was investigated. Thirty-one ACL injured female adolescents (ACLi, 15.3 ± 1.4yrs, 163.9 ± 6.6cm, 63.0 ± 9.3kg) and thirty-eight uninjured (CON, 13.2±1.7yrs, 161.7 ± 8.1cm, 50.6 ± 11.1kg) participated in this study. All participants performed a countermovement jump task, with 3D kinematics collected using a motion analysis system (Vicon, Nexus, Oxford, UK) at 200Hz, and a maximum isometric knee extension task on an isokinetic dynamometer (Biodex Medical Systems, New York, USA) for three trials. The peak torque was extracted from the isometric trials. Independent samples t-test compared the maximum jump height normalised by the dominant leg length between groups, paired samples t-test compared the maximum hip and knee extension and ankle plantar flexion velocities before take-off between limbs in both groups, and a Pearson's correlation test investigated the association between the isometric knee extension strength and jump height. The ACLi jumped 13% lower compared to the CON (p=0.022). In the ACLi, the maximum hip and knee extension and ankle plantar flexion velocities were greater in the non-injured limb, compared to the injured limb; however, no differences between limbs were found in the CON. The isometric knee extension strength of both limbs was positively correlated with jump height (limb 1: r=0.329; p=0.006, and limb 2: r=0.386; p=0.001; whereas limb 1 corresponds to the ACLi injured limb and CON non-dominant limb, and limb 2 to the ACLi non-injured limb and CON dominant limb). ACL injured female adolescents present lower jump height than controls and greater contribution of their non-injured limb, compared to their injured limb, during a countermovement jump task. Also, current results indicate that jump height is positively related to isometric knee extension strength measure

Abstract. OBJECTIVE. Knee varus malalignment increases medial knee compartment loading and is associated with knee osteoarthritis (OA) progression and severity. 1. Altered biomechanical loading and dysregulation of joint tissue biology drive OA progression, but mechanistic links between these factors are lacking. Subchondral bone structural changes are biomechanically driven, involve bone resorption, immune cell influx, angiogenesis, and sensory nerve invasion, and contribute to joint destruction and pain. 2. We have investigated mechanisms underlying this involving RANKL and alkaline phosphatase (ALP), which reflect bone resorption and mineralisation respectively. 3. and the axonal guidance factor Sema3A. Sema3A is osteotropic, expressed by mechanically sensitive osteocytes, and an inhibitor of sensory nerve, blood vessel and immune cell invasion. 4. Sema3A is also differentially expressed in human OA bone. 5. HYPOTHESIS: Medial knee compartment overloading in varus knee malalignment patients causes dysregulation of bone derived Sema3A signalling directly linking joint biomechanics to pathology and pain. METHODS. Synovial fluid obtained from 30 subjects with medial knee OA (KL grade II-IV) undergoing high tibial osteotomy surgery (HTO) was analysed by mesoscale discovery and ELISA analysis for inflammatory, neural and bone turnover markers. 11 of these patients had been previously analysed in a published patient-specific musculoskeletal model. 6. of gait estimating joint contact location, pressure, forces, and medial-lateral condyle load distribution in a published data set included in analyses. Data analysis was performed using Pearson's correlation matrices and principal component analyses. Principal Components (PCs) with eigenvalues greater than 1 were analysed. RESULTS. PC1 (32.94% of variation) and PC2 (25.79% of variation) from PCA analysis and correlation matrices separated patients according to correlated clusters of established inflammatory markers of OA pain and progression (IL6/IL8, r=0.754, p<0.001) and anti-inflammatory mediators (IL4/IL10, r=0.469, p=0.005). Bone turnover marker ALP was positively associated with KL grade (r=0.815, p=0.002) and negatively associated with IL10 (r=−0.402, p=0.018) and first peak knee loading pressures (r=−0.688, p=0.019). RANKL was positively associated with IL4 (r=0.489, p=0.003). Synovial fluid Sema3A concentrations showed separate clustering from all OA progression markers and was inversely correlated with TNF-α (r=−0.423, p=0.022) in HTO patients. Sema3A was significantly inversely correlated with total predicted force in the medial joint compartment (r=−0.621, p=0.041), mean (r=−0.63, p=0.038) and maximum (r=−0.613, p=0.045) calculated medial compartment joint pressures during the first phase and mean (r=−0.618, p=0.043) and maximum (r=−0.641, p=0.034) medial compartment joint pressures during midstance outputs of patient-specific musculoskeletal model. CONCLUSIONS. This study shows joint inflammatory status and mechanical overloading influence subchondral bone-remodelling. Synovial Sema3A concentrations are inversely correlated to patient-specific musculoskeletal model estimations of pathological medial overloading. This study reveals Sema3A as a biological mediator with capacity to induce OA pain and disease progression that is directly regulated by gait mechanical loading. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Abstract. Objectives. Neonatal motor development transitions from initially spontaneous to later increasingly complex voluntary movements. A delay in transitioning may indicate cerebral palsy (CP). The general movement optimality score (GMOS) evaluates infant movement variety and is used to diagnose CP, but depends on specialized physiotherapists, is time-consuming, and is subject to inter-observer differences. We hypothesised that an objective means of quantifying movements in young infants using motion tracking data may provide a more consistent early diagnosis of CP and reduce the burden on healthcare systems. This study assessed lower limb kinematic and muscle force variances during neonatal infant kicking movements, and determined that movement variances were associated with GMOS scores, and therefore CP. Methods. Electromagnetic motion tracking data (Polhemus) was collected from neonatal infants performing kicking movements (min 50° knee extension-flexion, <2 seconds) in the supine position over 7 minutes. Tracking data from lower limb anatomical landmarks (midfoot inferior, lateral malleolus, lateral knee epicondyle, ASIS, sacrum) were applied to subject-scaled musculoskeletal models (Gait2354_simbody, OpenSim). Inverse kinematics and static optimisation were applied to estimate lower limb kinematics (knee flexion, hip flexion, hip adduction) and muscle forces (quadriceps femoris, biceps femoris) for isolated kicks. Functional principal component analysis (fPCA) was carried out to reduce kicking kinematic and muscle force waveforms to PC scores capturing ‘modes’ of variance. GMOS scores (lower scores = reduced variety of movement) were collected in parallel with motion capture by a trained operator and specialised physiotherapist. Pearson's correlations were performed to assess if the standard deviation (SD) of kinematic and muscle force waveform PC scores, representing the intra-subject variance of movement or muscle activation, were associated with the GMOS scores. Results. The study compared GMOS scores, kinematics, and muscle force variances from a total of 26 infants with a mean corrected gestational age of 39.7 (±3.34) weeks and GMOS scores between 21 and 40. There was a significant association between the SD of the PC scores for knee flexion and the GMOS scores (PC1: R = 0.59, p = 0.002; PC2: R = 0.49, p = 0.011; PC3: R = 0.56, p = 0.003). The three PCs captured variances of the overall flexion magnitude (66% variance explained), early-to-late kick knee extension (20%), and continual to biphasic kicking (6%). For hip flexion, only the SD of PC1 correlated with GMOS scores (PC1: R = 0.52, p = 0.0068), which captured the variance of the overall flexion magnitude (81%). For the biceps femoris, the SD of PC1 and PC3 associated with GMOS scores (PC1: R = 0.50, p = 0.002; PC3: R = 0.45, p = 0.03), which captured the variance of the overall bicep force magnitude (79%) and early-to-late kick bicep activation (8%). Conclusions. Infants with reduced motor development as scored in the GMOS displayed reduced variances of knee and hip flexion and biceps femoris activation across kicking cycles. These findings suggest that combining objectively measured movement variances with existing classification methods could facilitate the development of more consistent and accurate diagnostic tools for early detection of CP. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Introduction and Objective. An important subset of patients is dissatisfied after total joint arthroplasty (TJA) due to residual functional impairment. This study investigated the assessment of objectively measured step-up performance following TJA, to identify patients with poor functional improvement after surgery, and to predict residual functional impairment during early postoperative rehabilitation. Secondary, longitudinal changes of block step-up (BS) transfers were compared with functional changes of subjective patient reported outcome measures (PROMs) following TJA. Materials and Methods. Patients with end stage hip or knee osteoarthritis (n = 76, m/f = 44/32; mean age = 64.4 standard deviation 9.4 years) were measured preoperatively and 3 and 12 months postoperatively. PROMs were assessed using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) function subscore. BS transfers were assessed by wearable-derived measures of time. In our cohort, subgroups were formed based on either 1) WOMAC function score or 2) BS performance, isolating the worst performing quartile (impaired) of each measure from the better performing others (non-impaired). Subgroup comparisons were performed with the Man-Whitney-U test and Wilcoxon Signed rank test resp. Responsiveness was calculated by the effect size, correlations with Pearson's correlation coefficient. A regression analysis was conducted to investigate predictors of poor functional outcome. Results. WOMAC function scores were strongly correlated to WOMAC pain scores (Pearson's r=0.67–0.84) and moderately correlated to BS performance (Pearson's r = 0.31–0.54). Prior to surgery, no significant differences for WOMAC function scores and BS performance were found between the impaired and non-impaired subgroups. One year after TJA, our cohort performed significantly better at WOMAC and BS with largest effect size for the non-impaired subgroups (0.62 and 0.43 resp.) At 12 months postop, 56% of patients allocated to the impaired subgroup defined by WOMAC, represented the impaired subgroup defined by BS. Allocation to the impaired subgroup at 3 months postop, raised the odds for belonging to the impaired subgroup at 12 months for WOMAC with an odds ratio=19.14 (67%) and for BS with an odds ratio=4.41 (42%). Conclusions. Assessment of BS performance following TJA reveals residual functional impairment that is not captured by pain-dominated PROMs. Its additional use may help to early identify those patients at risk for a poor outcome

Abstract. Objectives. Identifying risk factors for inferior outcomes after anterior cruciate ligament reconstruction (ACLR) is important for prognosis and patient information. This study aimed to ascertain if BMI, pre-operative scores, demographic data and concomitant injuries in patients undergoing ACLR affected patient-reported functional outcomes. Methods. A prospective review collected data from a single surgeon series of 278 patients who underwent arthroscopic ACLR. BMI, age, gender, graft choice, pre-op Lysholm score, meniscal and chondral injuries were recorded. The Lysholm score, hop test and KT1000 were used to measure post-op functional outcome at one year. Multiple regression analysis was used to determine factors that predicted Lysholm scores at one year. Results. The mean age was 29 years, with 58 female and 220 male patients. The mean pre-op Lysholm score was 53.8. One hunded and seventy-nine patients had meniscal injuries, of which 81 were medial, 60 lateral, and 38 bilateral. Eighteen patients also had chondral injury and 106 patients had no other associated injury. Age, gender, graft type and presence of meniscal or chondral injuries did not affect one-year post-operative Lysholm scores. A BMI greater than 30, physio compliance and preoperative Lysholm scores helped predict one-year post-operative Lysholm scores (p=0.02). Pearson's correlation found a direct link between BMI and post-operative Lysholm (p=0.03). Conclusions. BMI, physio compliance and pre-operative Lysholm scores are the most significant determinants of short-term functional outcome after ACLR. However, the effects of associated injuries may be apparent in the long-term as degenerative changes set in or the continued detriment resulting from the concomitant injury affect outcome. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Abstract. Objectives. Accurate orientation of the acetabular component during a total hip replacement is critical for optimising patient function, increasing the longevity of components, and reducing the risk of complications. This study aimed to determine the validity of a novel VR platform (AescularVR) in assessing acetabular component orientation in a simulated model used in surgical training. Methods. The AescularVR platform was developed using the HTC Vive® VR system hardware, including wireless trackers attached to the surgical instruments and pelvic sawbone. Following calibration, data on the relative position of both trackers are used to determine the acetabular cup orientation (version and inclination). The acetabular cup was manually implanted across a range of orientations representative of those expected intra-operatively. Simultaneous readings from the Vicon® optical motion capture system were used as the ‘gold standard’ for comparison. Correlation and agreement between these two methods was determined using Bland-Altman plots, Pearson's correlation co-efficient, and linear regression modelling. Results. A total of 55 separate orientation readings were obtained. The mean average difference in acetabular cup version and inclination between the Vicon and VR systems was 3.4° (95% CI: −3–9.9°), and −0.005° (95% CI: −4.5–4.5°) respectively. Strong positive correlations were demonstrated between the Vicon and VR systems in both acetabular cup version (Pearson's R = 0.92, 99% CI: 0.84–0.96, p<0.001), and inclination (Pearson's R = 0.94, 99% CI: 0.88–0.97, p<0.001). Using linear regression modelling, the adjusted R. 2. for acetabular version was 0.84, and 0.88 for acetabular inclination. Conclusion. The results of this study indicate that the AescularVR platform is highly accurate and reliable in determining acetabular component orientation in a simulated environment. The AescularVR platform is an adaptable tracking system, which may be modified for use in a range of simulated surgical training and educational purposes, particularly in orthopaedic surgery. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Objectives. We have previously investigated an association between the genome copy number variation (CNV) and acetabular dysplasia (AD). Hip osteoarthritis is associated with a genetic polymorphism in the aspartic acid repeat in the N-terminal region of the asporin (ASPN) gene; therefore, the present study aimed to investigate whether the CNV of ASPN is involved in the pathogenesis of AD. Methods. Acetabular coverage of all subjects was evaluated using radiological findings (Sharp angle, centre-edge (CE) angle, acetabular roof obliquity (ARO) angle, and minimum joint space width). Genomic DNA was extracted from peripheral blood leukocytes. Agilent’s region-targeted high-density oligonucleotide tiling microarray was used to analyse 64 female AD patients and 32 female control subjects. All statistical analyses were performed using EZR software (Fisher’s exact probability test, Pearson’s correlation test, and Student’s t-test). Results. CNV analysis of the ASPN gene revealed a copy number loss in significantly more AD patients (9/64) than control subjects (0/32; p = 0.0212). This loss occurred within a 60 kb region on 9q22.31, which harbours the gene for ASPN. The mean radiological parameters of these AD patients were significantly worse than those of the other subjects (Sharp angle, p = 0.0056; CE angle, p = 0.0076; ARO angle, p = 0.0065), and all nine patients required operative therapy such as total hip arthroplasty or pelvic osteotomy. Moreover, six of these nine patients had a history of operative or conservative therapy for developmental dysplasia of the hip. Conclusions. Copy number loss within the region harbouring the ASPN gene on 9q22.31 is associated with severe AD. A copy number loss in the ASPN gene region may play a role in the aetiology of severe AD. Cite this article: T. Sekimoto, M. Ishii, M. Emi, S. Kurogi, T. Funamoto, Y. Yonezawa, T. Tajima, T. Sakamoto, H. Hamada, E. Chosa. Copy number loss in the region of the ASPN gene in patients with acetabular dysplasia: ASPN CNV in acetabular dysplasia. Bone Joint Res 2017;6:439–445. DOI: 10.1302/2046-3758.67.BJR-2016-0094.R1

One of the main surgical goals when performing a total knee replacement (TKR) is to ensure the implants are properly aligned and correctly sized; however, understanding the effect of alignment and rotation on the biomechanics of the knee during functional activities is limited. Cardiff University has unique access to a group of local patients who have relatively high frequency of poor alignment, and early failure. This provides a rare insight into how malalignment of TKR's can affect patients from a clinical and biomechanical point of view to determine how to best align a TKR. This study aims to explore relationship clinical surgical measurements of Implant alignment with in-vivo joint kinematics. 28 patient volunteers (with 32 Kinemax (Stryker) TKR's were recruited. Patients undertook single plane video fluoroscopy of the knee during a step-up and step-down task to determine TKR in-vivo kinematics and centre of rotation (COR). Joint Track image registration software (University of Florida, USA) was used to match CAD models of the implant to the x-ray images. Hip-Knee-Ankle (HKA) was measured using long-leg radiographs to determine frontal plane alignment. Posterior tibial slope angle was calculated using radiographs. An independent sample t-test was used to explore differences between neutral (HKA:-2° to 2°), varus (≥2°) and valgus alignment (≤-2°) groups. Other measures were explored across the whole cohort using Pearson's correlations (SPSS V23). There was found to be no statistical difference between groups or correlations for HKA. The exploratory analysis found that tibial slope correlated with Superior/Inferior translation ROM during step up (r=−0.601, p<0.001) and step down (r=−.512, p=0.03) the position of the COR heading towards the lateral (r=−.479, p=0.006) during step down. Initial results suggest no relationship between frontal plane alignment and in-vivo. Exploratory analyses have found other relationships that are worthy of further research and may be important in optimizing function

There are many factors which contribute to function after TKA. In this study we focus on the effect of varus-valgus (VV) balancing measured externally. A loose knee can show instability (Sharkey 2014) while too tight, flexion can be limited. Equal lateral-medial balancing at surgery leads to a better result (Unitt 2008; Gustke 2014), which is generally the surgical goal. Indeed similar varus and valgus laxity angles have been found in most studies in vitro (Markolf 2015; Boguszewski 2015) and in vivo (Schultz 2007; Clarke 2016; Heesterbeek 2008). The angular ranges have been 3–5 degrees at 10–15 Nm of knee moment, females having the higher angles. The goal of this study was to measure the varus and valgus laxity, as well as the functional outcome scores, of two cohorts; well-functioning total knees after at least one year follow-up, and subjects with healthy knees in a similar age group to the TKR's. Our hypothesis was that the results will be equal in the two groups. 50 normal subjects average age 66 (27 male, 23 female) and 50 TKA at 1 year follow-up minimum average age 68 years (16 male, 34 female) were recruited in this IRB study. The TKA's were performed by one surgeon (PAM) of one TKA design, balancing by gap equalization. Subjects completed a KSS evaluation form to determine functional, objective, and satisfaction scores. Varus and valgus measurements were made using the Smart Knee Fixture (Borukhov 2016) at 20 deg flexion with a moment of 10 Nm. The statistical results demonstrated that there was no significant difference in either varus or valgus laxity between the two groups (p= 0.9, 0.3 respectively). Pearson's correlation coefficient between varus and valgus laxity of the healthy group was 0.42, while for the TKA group was 0.55. In both cohorts varus laxity was significant higher than valgus laxity (p= 0.001. e. −5. for healthy subjects and p=0.0001 for TKA). The healthy group had higher functional and objective KSS scores (p= 0.005. e. −4. , and p=0.004. e. −5. respectively), but the same satisfaction scores as the TKA (p=0.3). No correlation was found between the total laxity of the TKA group and the KSS scores (functional, objective and satisfaction). Total laxity in females was significantly higher than in males in the healthy group, but no differences was found in the TKA group. The hypothesis of equal varus and valgus angles in the 2 groups was supported. The larger varus angle implied a less stiff lateral collateral compared with the medial collateral. If the TKA's were balanced equally at surgery, it is possible there was ligament remodeling over time. However the functional scores were inferior for the TKA compared with normal. This finding has not been highlighted in the literature so far. The causes could include weak musculature (Yoshida 2013), non-physiologic kinematics due to the TKA design, or the use of rigid materials in the TKA. The result presents a challenge to improve outcomes after TKA

Introduction. The STarT Back trial demonstrated that targeting back pain treatment according to patient prognosis (low, medium or high-risk subgroups) is effective. However, the mechanisms leading to these improved treatment outcomes remain unknown. This study aimed to identify which psychological variables included in the study were mediating treatment outcome for all patients and within the low, medium and high-risk subgroups. Methods. Secondary analysis was conducted on 466 patients randomised to the active treatment arm with 4-month follow-up available. Psychological variables included depression (HADs), fear (TSK), catastrophising (PCS), bothersomeness and illness perception constructs (IPQ brief) e.g. personal control. Treatment outcome was characterised using change in disability score (RMDQ) at 4-months. Residualised change scores were calculated for each variable and Pearson's correlations were calculated overall and at the subgroup level to determine potential mediating variables for disability improvement. Results. Overall, correlations with RMDQ change were .62 for change in bothersomeness, .56 for change in catastrophising, .51 for change in fear, .48 for change in anxiety, .58 for change in depression, −.32 for change in personal control and .40 for change in symptom identity. The strength of correlation generally increased from low to high-risk subgroups, e.g. bothersomeness (low=.54, high=.70). However, the predominant variables mediating treatment outcome were common across risk-groups. Conclusion. The psychological variables which were highly correlated with improvements in disability were bothersomeness, depression and catastrophising. This finding was consistent across low, medium and high-risk subgroups. This study is ongoing and further mediation analysis using structural equation modelling is in progress. Conflicts of Interest. None. Source of Funding. NIHR Spinal Pain Programme grant

Aim. To assess whether the Oxford Hip Score (OHS), is reflective of objectively assessed functional performance (timed up and go (TUG), 30 sec sit to stand (ST), 6 minute walk test (6MWT), stair climb performance (SCP), and gait speed (GS)) in patients undergoing total hip arthroplasty (THA). Methods. 50 patients undergoing THA were prospectively recruited after ethical approval. Demographics and objective physical performance were assessed (TUG, ST, 6MWT, SCP, GS), as was the OHS preoperatively, and at 6 weeks, 6 months and 9 to 12 months postoperatively. Pearson's correlation coefficient was used to assess relationships, with p<0.05 statistically significant. Results. Average age of the cohort was (mean (SD)) 67.8 (9.4) years in males (n=21) and 64.2 (10.2) years in females (n=29). Due to loss to follow up, 32 patients were assessed at 6 weeks, 29 at 6 months and 26 at 9 to 12 months. Preoperatively OHS correlated weakly with TUG (r = − 0.327, p=0.022), ST (r = 0.345, p=0.015) and SCP (r = − 0.330, p=0.022). At 6 months, OHS correlated moderately with all the objective measures assessed; TUG (r = − 0.480, p=0.006), ST (r = 0.454, p=0.010), 6MWT (r=0.507, p = 0.004) and SCP (r = 0.534, p=0.002), with the relationships less evident at 6 weeks (no significant correlations) and 9 to 12 months (moderate correlation with 6MWT only (r = 0.512, p=0.009). Conclusions. The OHS most accurately reflects objective functional performance at 6 months postoperatively, perhaps indicating this time point may be optimal in terms of postoperative recovery

Introduction. Anteromedial osteoarthritis of the knee (anteromedial gonarthrosis-AMG) is a common form of knee arthritis. In a clinical setting, knee arthritis has always been assessed by plain radiography in conjunction with pain and function assessments. Whilst this is useful for surgical decision making in bone on bone arthritis, plain radiography gives no insight to the earlier stages of disease. In a recent study 82% of patients with painful arthritis had only partial thickness joint space loss on plain radiography. These patients are managed with various surgical treatments; injection, arthroscopy, osteotomy and arthroplasty with varying results. We believe these varying results are in part due to these patients being at different stages of disease, which will respond differently to different treatments. However radiography cannot delineate these stages. We describe the Magnetic Resonance Imaging (MRI) findings of this partial thickness AMG as a way of understanding these earlier stages of the disease. Method. 46 subjects with symptomatic partial thickness AMG underwent MRI assessment with dedicated 3 Tesla sequences. All joint compartments were scored for both partial and full thickness cartilage lesions, osteophytes and bone marrow lesions (BML). Both menisci were assessed for extrusion and tear. Anterior cruciate ligament (ACL) integrity was also assessed. Osteophytes were graded on a four point scale in the intercondylar notch and the lateral margins of the joint compartments. Scoring was performed by a consultant radiologist and clinical research fellow using a validated MRI atlas with consensus reached for disagreements. The results were tabulated and relationships of the interval data assessed with linear by linear Chi2 test and Pearson's Correlation. Results. All cases had medial femoral cartilage loss; 22% partial and 78% full thickness. 79% showed medial tibial loss, however in no cases was there medial tibial loss without femoral loss. 10 cases had lateral compartment partial thickness cartilage loss. Again, there was no tibial loss without femoral loss present. Increasing size of intercondylar notch osteophyte is associated with increasing ACL damage (p=0.001). Independent to this, increasing ACL damage is associated with lateral femoral condyle cartilage loss (p=0.002). Throughout the knee the incidence of BMLs increased with increasing cartilage loss (p=0.025). Only 13% of medial menisci were normal. As meniscal damage increases, so does the incidence of BMLs in the same compartment (p=0.03). Discussion. We describe the MRI findings of early AMG with partial thickness joint space loss. In all cases there was medial femoral loss, either with or without tibial loss. We believe the disease begins on the medial femoral condyle and progresses through the joint in stages. Later stages are associated with damage to the other structures in the knee, such as the meniscus and the ACL. Damage to the ACL is associated with increasing osteophytosis. This description is the first step in describing the stages of early AMG. Description of these stages is important since we believe the outcome of surgical intervention may be dependant on these and they may guide future therapy

Summary Statement. Navigated total knee arthroplasty (TKA) is becoming increasingly popular in the United States. Compared to traditional unnavigated TKA, the use of navigation is associated with decreased blood transfusions and shorter hospital stays. Introduction. Navigated total knee arthroplasty (TKA) is a recent modification to standard TKA with many purported benefits in regards to component positioning. Controversy currently exists though regarding its clinical benefits. The purpose of this study was to assess recent national trends in navigated and unnavigated total knee arthroplasty and to evaluate perioperative outcomes for each group. Methods. International Classification of Disease - 9th Revision (ICD-9) procedure codes were used to search the National Hospital Discharge Survey (NHDS) for all patients admitted to US hospitals after navigated and unnavigated TKA for each year between 2005 and 2010. Data regarding patient demographics, hospitalization length, discharge disposition, blood transfusions, deep vein thrombosis, pulmonary embolism, mortality, and hospital location were gathered from the NHDS. Trends were evaluated by linear regression with Pearson's correlation coefficient (r) and statistical comparisons were made using Student's t-test, z-test for proportions, and chi-square analysis with a significance level of 0.05. Results. 22,443 patients admitted for TKA were identified. 578 (2.6%) of these patients had a TKA utilizing navigation. After adjusting for fluctuations in annual TKA performed, the use of navigation in TKA demonstrated a strong positive correlation with time (r=0.71), significantly increasing from an average utilization rate of 2.2% between 2005–2007 to 3.2% between 2008–2010 (p<0.01). The location of the hospital was found to significantly impact the utilization of navigation, with the lowest rate seen in the Midwest region (2.0%) of the US and the highest rate seen in the South region (3.0%). The mean age of navigated patients was 66.0 years. This group included 211 men and 367 women. The unnavigated group had a mean patient age that was insignificantly higher at 66.4 years (p=0.37) and included 7,815 men and 14,047 women. Gender was also not significantly different (p=0.71) between those with navigated TKA and those with unnavigated TKA. The number of medical co-morbidities was significantly higher in those with navigation (mean 5.4 diagnoses) than those without navigation (mean 5.1 diagnoses, p=0.01). Average hospitalization length also varied based on navigation status, with significantly shorter stays for those with navigation (3.3 days, range 1–11) compared to those without (3.6 days, range 1–73, p<0.01). The rate of blood transfusion was significantly lower in the navigated group (13.0%) versus the unnavigated group (17.4%, p<0.01). There was no difference in the rate of deep vein thrombosis (0.69% vs 0.53%, p=0.64) or pulmonary embolism (0.17% vs 0.47%, p=0.10). Mortality was also not significantly different for navigated TKA (0.17%) when compared to unnavigated TKA (0.08%, p=0.61). Discharge disposition did not significantly vary based on navigation status either, with 65.5% of navigated patients and 67.0% of unnavigated patients able to go directly home (p=0.55) after their inpatient stay. Discussion/Conclusion. This study demonstrates that the use of navigated TKA in the US is rising. Additionally, despite having more medical co-mobidities, the navigated population required less blood transfusions and shorter lengths of stay. Interestingly, navigation utilization demonstrated variability based on hospital region. The reasons for this are not immediately clear, but may be related to differences in regional training

Summary Statement. Total hip arthroplasty and hemi-arthroplasty are becoming increasingly popular in the treatment of femoral neck fractures in the United States. Both appear to be safe and effective treatment options, with rare acute adverse events and low mortality. Introduction. Femoral neck fractures are one of the most frequent orthopaedic injuries seen in the United States (US). Total hip arthroplasty (THA) and hemiarthroplasty (HA) are commonly used to treat displaced intra-capsular femoral neck fractures, but controversy currently exists regarding the preferred modality. The purpose of this study was to assess recent national trends in THA and HA performed for femoral neck fracture and to evaluate perioperative outcomes for each treatment group. Methods. International Classification of Disease - 9th Revision (ICD-9) diagnosis codes were used to search the National Hospital Discharge Survey (NHDS) for all patients admitted to US hospitals after femoral neck fracture for each year between 2001 and 2010. ICD-9 procedure codes were then used to identify patients from this fracture population who underwent THA or HA. Data regarding patient demographics, hospitalization length, discharge disposition, in-hospital adverse events (pulmonary embolus, deep vein thrombosis, blood transfusion, mortality) and hospital size/location were gathered from the NHDS. Trends were evaluated by linear regression with Pearson's correlation coefficient (r) and statistical comparisons were made using Student's t-test, z-test for proportions, and chi-square analysis with a significance level of 0.05. Results. 12,757 patients with a femoral neck fracture were identified. 582 (4.6%) were treated with THA and 6,697 (52.5%) received HA. After adjusting for fluctuations in annual fracture incidence, the use of THA to treat femoral neck fractures demonstrated a strong positive correlation with time (r=0.91), significantly increasing from an average rate of 4.2% between 2001–2005 to 5.0% between 2006–2010 (p=0.04). Similarly, the use of HA demonstrated a strong positive correlation with time (r=0.89) and significantly increased from an average rate of 51.0% to 54.7% (p<0.01). The frequency of THA use also demonstrated significant (p=0.01) differences based on US region, with a rate of 3.3% in the West region and 5.2% in the South. No regional differences were seen for HA (p=0.07). Hospital size significantly impacted HA use, with the lowest rate seen in hospitals under 100 beds (47.4%) and the highest rate in those with 200–299 beds (56.0%, p<0.01). No size differences were seen for THA (p=0.10). The THA group had a mean patient age of 76.9 years and included 164 men and 418 women. The HA group had a mean patient age that was significantly higher at 81.1 years (p<0.01) and included 1744 men and 4953 women. Gender was not significantly different (p=0.27) between the groups. Average hospitalization length was significantly longer for THA (7.8 days, range 1–312) compared to HA (6.7 days, range 1–118, p<0.01). Discharge disposition also varied by treatment group, with 23.2% of THA patients able to go directly home compared to only 11.6% of HA patients (p<0.01). Blood transfusion rate was significantly higher for THA (30.4%) compared to HA (25.7%, p=0.02). No significant difference was noted between THA and HA in regards to rate of PE (0.5% versus 0.7%, p=0.52), rate of DVT (1.2% versus 0.8%, p=0.50) or mortality (1.8% versus 2.9%, p=0.09). Discussion/Conclusion. This study demonstrates that the use of THA and HA in the treatment of femoral neck fractures are rising and that both are safe and effective treatment options, with equally rare acute adverse events and low mortality. Interestingly, treatment choice demonstrated variability based on hospital region and size. The reasons for this are not immediately clear, but may be related to differences in regional training and availability of trauma/reconstruction subspecialists

Summary Statement. Pulmonary embolism (PE) after total knee arthroplasty can have a significant impact on patient outcomes and healthcare costs. Efforts to prevent or minimise PE over the last 10 years have not had a significant impact on its occurrence at the national level. Introduction. Pulmonary embolism (PE) is a rare but known potentially devastating complication of total knee arthroplasty (TKA). Significant healthcare resources and pharmaceutical research has been recently focused on preventing this complication but limited data exists regarding the early results of this great effort. The purpose of this study was to assess recent national trends in PE occurrence after TKA and evaluate patient outcomes related to this adverse event. Methods. International Classification of Disease - 9th Revision (ICD-9) procedure codes were used to search the National Hospital Discharge Survey (NHDS) for all patients admitted to US hospitals after primary TKA for each year between 2001 and 2010. ICD-9 diagnosis codes were then used to identify patients from this population who developed an acute PE during the same admission. Data regarding patient demographics, hospitalization length, discharge disposition, deep vein thrombosis, mortality, and hospital size/location were gathered from the NHDS. Trends were evaluated by linear regression with Pearson's correlation coefficient (r) and statistical comparisons were made using Student's t-test, z-test for proportions, and chi-square analysis with a significance level of 0.05. Results. 35,220 patients admitted for a primary TKA were identified. 159 (0.045%) of these patients developed an acute PE during the same admission. After adjusting for fluctuations in annual TKA performed, the development of PE after TKA demonstrated a weak negative correlation with time (r=0.17), insignificantly decreasing from an average rate of 0.049% between 2001–2005 to 0.041% between 2006–2010 (p=0.26). The size of the hospital was found to significantly impact the incidence of PE and primary TKA, with the lowest rate seen in hospitals under 100 beds (0.23%) and the highest rate seen in those with over 500 beds (0.65%, p=0.01). No significant differences in PE incidence were noted based on US region (p=0.38). The mean age of patients with PE was 67.7 years. This group included 54 men and 105 women. The non-PE group had a mean patient age that was insignificantly lower at 66.6 years (p=0.21) and included 12,450 men and 22,611 women. Gender was also not significantly different (p=0.68) between those with PE and those without PE. The number of medical co-morbidities was significantly higher in those with PE (mean 6.42 diagnoses) than those without PE (mean 4.89 diagnoses, p<0.01). Average hospitalization length also varied based on PE status, with significantly longer stays for those with PE (8.2 days, range 2–53) compared to those without PE (3.7 days, range 1–95, p<0.01). The rate of deep vein thrombosis was higher in the PE group (12.7%) versus the non-PE group (0.48%, p<0.01). Mortality was also significantly higher for the PE group (3.9%) compared to the non-PE group (0.09%, p<0.01). Discharge disposition did not significantly vary based on PE status, with 61.5% of PE and 64.0% of non-PE patients able to go directly home (p=0.59) after their inpatient stay. Discussion/Conclusion. This study demonstrates that PE can have a significant impact on patient outcomes and healthcare costs, with an associated 43-fold increase in mortality and a doubling of the inpatient admission duration. Additionally, although the risk of PE after primary TKA remains rare, it still persists. Efforts to prevent or minimise this complication over the last 10 years have not had a significant impact on its occurrence at the national level. This risk of PE appears to be greatest in patients with multiple medical co-morbidities and established DVTs. Interestingly, the PE rate also demonstrated variability based on hospital size. The reasons for this are not clear, but we suspect larger hospitals are more likely to be tertiary-care centers and thus care for more medically-complex patients

Summary. Upper extremity activity was similar in patients and healthy subjects, showing no significant asymmetry between arms within subjects. Further improvements (e.g. thresholds, filters, inclinometer function) are needed to show the clinical value of AM for patients suffering shoulder complaints. Introduction. Activity monitoring is becoming a popular outcome tool especially in orthopaedics. The suitability of a single 3D acceleration-based activity monitor (AM) for patients with lower-extremity problems has been shown. However less is known about its feasibility to monitor upper-extremity activity. Insight into the amount and intensity of upper-extremity activity of the affected and non-affected arm (asymmetry) may be of added value for diagnostics, therapy choice and evaluating treatment effects. This study investigates the feasibility of a single AM to evaluate (asymmetry in) upper-extremity activity in daily life. Methods. Upper-extremity activity was measured in 12 patients with subacromial impingent syndrome (59±12yr) and 10 healthy subjects (29±11yrs). Subjects wore a single 3D accelerometer at both arms, just above the base of the Hueter triangle, for one day (min. 8 hours). Specific algorithms were used to derive quantity (activity duration, rest periods) and intensity (low-high) activity parameters (% of the day). The ratio in % activity between non-affected (dominant) and affected (non-dominant) arm was calculated. Asymmetry was expressed as the %-difference in activity between arms with regards to the non-affected (dominant) arm. Also popular PROMs were completed: DASH score (range 0–100;0=best) and SST score (range 0–12; 0=best). Independent t-test, Mann-Whitney U test, Pearson's r correlations were performed. Results. No significant differences in activity duration (Healthy: 50%, patients: 57% of the day) and intensity of upper-extremity activity were found between patients and healthy subjects, although PROMs were significantly worse in patients. Patients and healthy subjects use both arms in similar amounts of time per day. This corresponds to the ratio which almost equals 1 and the low asymmetry values (<10%) in both groups. Also the amount activity in low and high intensity was comparable between affected (non-dominant) and non-affected (dominant) arm. No correlations were found between AM data and PROMs. Discussion and Conclusion. Patients and healthy subjects move their upper arms approximately 53% of the day. No differences in amount and intensity of upper-extremity activity were found between healthy subjects and patients, neither between both arms. This suggests that subjects perform daily activities independent of pain, complaints or arm dominance. It could also hint at the algorithm operating with a too low activity threshold to include shuffling or misclassifying excitations from walking as intense arm movement. Both issues can be adjusted by adjusting thresholds and filter settings. The asymmetry in upper-extremity activity of healthy subjects (9.1%) assumes that a 10% asymmetry in arm activity seems natural, which coincides with similar values reported for functional shoulder tests (Koerver et al. CORS 2010). The lack of correlations between AM and PROMs suggests that both measure different outcome dimensions. The AM has some limitations which should be considered when improving the clinical feasibility of upper-extremity activity monitoring. The AM only allows to measure acceleration-related activities (speed, intensity), while upper-extremity activity often involves static force-related activities. However, the inclinometer capacity of accelerometers allows to measure upper-extremity activity at different elevations (upper arm above/below shoulder). This may add qualitative information, relevant for clinical purposes

Aims

Osteoporosis and abnormal bone metabolism may prove to be significant factors influencing the outcome of arthroplasty surgery, predisposing to complications of aseptic loosening and peri-prosthetic fracture. We aimed to investigate baseline bone mineral density (BMD) and bone turnover in patients about to undergo arthroplasty of the hip and knee.

The role of inflammatory cells and their products in tendinopathy is not completely understood. Pro-inflammatory cytokines are upregulated after oxidative and other forms of stress. Based on observations that increased cytokine expression has been demonstrated in cyclically-loaded tendon cells we hypothesised that because of their role in oxidative stress and apoptosis, pro-inflammatory cytokines may be present in rodent and human models of tendinopathy. A rat supraspinatus tendinopathy model produced by running overuse was investigated at the genetic level by custom micro-arrays. Additionally, samples of torn supraspinatus tendon and matched intact subscapularis tendon were collected from patients undergoing arthroscopic shoulder surgery for rotator-cuff tears and control samples of subscapularis tendon from ten patients with normal rotator cuffs undergoing arthroscopic stabilisation of the shoulder were also obtained. These were all evaluated using semiquantitative reverse transcription polymerase chain-reaction and immunohistochemistry.

We identified significant upregulation of pro-inflammatory cytokines and apoptotic genes in the rodent model (p = 0.005). We further confirmed significantly increased levels of cytokine and apoptotic genes in human supraspinatus and subscapularis tendon harvested from patients with rotator cuff tears (p = 0.0008).

These findings suggest that pro-inflammatory cytokines may play a role in tendinopathy and may provide a target for preventing tendinopathies.

Malpositioning of the trochanteric entry point during the introduction of an intramedullary nail may cause iatrogenic fracture or malreduction. Although the optimal point of insertion in the coronal plane has been well described, positioning in the sagittal plane is poorly defined.

The paired femora from 374 cadavers were placed both in the anatomical position and in internal rotation to neutralise femoral anteversion. A marker was placed at the apparent apex of the greater trochanter, and the lateral and anterior offsets from the axis of the femoral shaft were measured on anteroposterior and lateral photographs. Greater trochanteric morphology and trochanteric overhang were graded.

The mean anterior offset of the apex of the trochanter relative to the axis of the femoral shaft was 5.1 mm (sd 4.0) and 4.6 mm (sd 4.2) for the anatomical and neutralised positions, respectively. The mean lateral offset of the apex was 7.1 mm (sd 4.6) and 6.4 mm (sd 4.6), respectively.

Placement of the entry position at the apex of the greater trochanter in the anteroposterior view does not reliably centre an intramedullary nail in the sagittal plane. Based on our findings, the site of insertion should be about 5 mm posterior to the apex of the trochanter to allow for its anterior offset.

Cite this article: Bone Joint J 2014;96-B:1274–81.