Aims

The aim of this study was to investigate the distribution of phenotypes in Asian patients with end-stage osteoarthritis (OA) and assess whether the phenotype affected the clinical outcome and survival of mechanically aligned total knee arthroplasty (TKA). We also compared the survival of the group in which the phenotype unintentionally remained unchanged with those in which it was corrected to neutral.

Aims

A substantial fraction of patients undergoing knee arthroplasty (KA) or hip arthroplasty (HA) do not achieve an improvement as high as the minimal clinically important difference (MCID), i.e. do not achieve a meaningful improvement. Using three patient-reported outcome measures (PROMs), our aim was: 1) to assess machine learning (ML), the simple pre-surgery PROM score, and logistic-regression (LR)-derived performance in their prediction of whether patients undergoing HA or KA achieve an improvement as high or higher than a calculated MCID; and 2) to test whether ML is able to outperform LR or pre-surgery PROM scores in predictive performance.

Aims

This is a multicentre, prospective assessment of a proportion of the overall orthopaedic trauma caseload of the UK. It investigates theatre capacity, cancellations, and time to surgery in a group of hospitals that is representative of the wider population. It identifies barriers to effective practice and will inform system improvements.

Aims

BoneMaster is a thin electrochemically applied hydroxyapatite (HA) coating for orthopaedic implants that is quickly resorbed during osseointegration. Early stabilization is a surrogacy marker of good survival of femoral stems. The hypothesis of this study was that a BoneMaster coating yields a fast early and lasting fixation of stems.

Aims

We aimed to compare the implant survival, complications, readmissions, and mortality of Vancouver B2 periprosthetic femoral fractures (PFFs) treated with internal fixation with that of B1 PFFs treated with internal fixation and B2 fractures treated with revision arthroplasty.

Aims

Time to treatment initiation (TTI) is generally defined as the time from the histological diagnosis of malignancy to the initiation of first definitive treatment. There is no consensus on the impact of TTI on the overall survival in patients with a soft-tissue sarcoma. The purpose of this study was to determine if an increased TTI is associated with overall survival in patients with a soft-tissue sarcoma, and to identify the factors associated with a prolonged TTI.

Aims

Malreduction of the syndesmosis has been reported in up to 52% of patients after fixation of ankle fractures. Multiple radiological parameters are used to define malreduction; there has been limited investigation of the accuracy of these measurements in differentiating malreduction from inherent anatomical asymmetry. The purpose of this study was to identify the prevalence of positive malreduction standards within the syndesmosis of native, uninjured ankles.

Aims

Functional rehabilitation has become an increasingly popular treatment for Achilles tendon rupture (ATR), providing comparably low re-rupture rates to surgery, while avoiding risks of surgical complications. Limited evidence exists on whether gap size should affect patient selection for this treatment option. The aim of this study was to assess if size of gap between ruptured tendon ends affects patient-reported outcome following ATR treated with functional rehabilitation.

Aims

The use of frozen tumour-bearing autograft combined with a vascularized fibular graft (VFG) represents a new technique for biological reconstruction of massive bone defect. We have compared the clinical outcomes between this technique and Capanna reconstruction.

Aims

The aim of this study was to determine the risk of local recurrence and survival in patients with osteosarcoma based on the proximity of the tumour to the major vessels.

Objectives

Meropenem may be an important drug in the treatment of open tibial fractures and chronic osteomyelitis. Therefore, the objective of this study was to describe meropenem pharmacokinetics in plasma, subcutaneous adipose tissue (SCT), and cancellous bone using microdialysis in a porcine model.

Introduction. In total knee arthroplasty, the aim is to relieve pain and provide a stable, functional knee. Sagittal stability is crucial in enabling a patient to return to functional activities. Knee implants with a medial pivot (MP) design are thought to more accurately reproduce the mechanics of the native joint, and potentially confer greater antero-posterior stability through the range of flexion than some other implant designs. Aim. This study aims to compare the sagittal stability of four different total knee arthroplasty implant designs. Method. Comparison was made between four different implant designs: medial pivot (MP), two different types of cruciate retaining (CR1 and CR 2) and deep dish (DD). A cohort of 30 Medial Pivot (MP) knees were compared with matched patients from each of the other designs, 10 in each group. Patients were matched for age, body mass index and time to follow up. Clinical examination was carried out by an orthopaedic surgeon blinded to implant type, and sagittal stability was tested using a KT1000 knee arthrometer, applying 67N of force at 30˚ and 90˚. Results. The MP knee was more stable than the CR1 knee at both 30º (mean movement: 1.37mm vs 2.48mm, p=0.037) and 90º (1.68mm vs 2.37mm, p=0.030). The MP knee was more stable than the CR2 knee at 30º (0.98mm vs1.33mm, p=0.013). The MP knee also demonstrated less movement at 90 º (0.98mm vs 1.33mm), but this was not statistically significant (p=0.156). The MP knee was more stable than the DD knee at 30 º (0.48mm vs 1.33mm, p=0.03) and 90 º (0.67mm vs 1.15mm, p=0.048). Overall the medial pivot design was more stable than all non-medial pivot designs at 30 º (0.8mm vs1.66mm, p=0.003) and 90 º (1.1mm vs 1.61mm, p= 0.008). Conclusion. Overall, the medial pivot design demonstrated significantly greater antero-posterior stability than all other design types included in this study. Correlation with patient reported outcome scales will allow insight into whether these statistically significant differences are also clinically significant

Introduction. Although weight-bearing CT of the foot definitely reflects the morphology and deformity of joint, it is hard to obtain the standing CT due to difficulty of availability. Although 3D imaging reconstruction using radiographs has been reported in other joints, there is no study about foot joint. The purpose of this study is to develop a semi-automatic method based on a deformable surface fitting for achieving the weight-bearing 3D model reconstruction from standing radiographs for foot. Methods. Our method is based on a Laplacian surface deformation framework using a template model of foot. As pre- processing step, we obtained template surface meshes having the average shapes of foot bones (talus, calcaneus) from standing CT images (Planmed Verity) in 10 normal volunteers. In the reconstruction step, the surface meshes are deformed following guided user inputs with geometric constraints to recover the target shapes of 30 patients while preserving average bone shape and smoothness. Finally, we compared reconstructed 3D model to original standing CT images. Analysis was performed using Dice coefficients, average shape distance, maximal shape distance. Results. The obtained reconstruction model is close to the actual standing foot geometry (Dice coefficients 0.89, average shape distance 0.88 mm, maximum shape distance 6.33 mm). We present the accuracy and robustness of our method via comparison between the reconstructed 3D models and the original bone surfaces. Conclusions. Weight-bearing 3D foot model reconstruction from standing radiographs is concise and the effective method for analysis of foot joint alignment and deformity

Introduction. Total hip arthroplasty (THA) is a commonly performed surgical procedure for the treatment of hip arthritis. Approximately 50,000 THAs are performed annually in Canada. The costs incurred to the healthcare system are tremendous, amounting to anywhere between 4.3 and 7.3 billion dollars each year. Despite the substantial financial burden of THA to the Canadian healthcare system, few studies have provided accurate cost estimations of this procedure. Purpose. To determine the impact of surgical approach on costs of THA from a hospital perspective, and provide an updated cost estimation of THA within a publically funded healthcare system. Methods. We recruited patients undergoing a THA through an anterior, posterior, or lateral approach for study participation. A single surgeon was designated to perform every case using the surgical approach of their expertise. Each patient received standardized implants: a collared, hydroxyapatite-coated, cementless femoral stem (Corail TM stem, DePuy Orthopaedics Inc., Warsaw, IN), a cementless acetabular cup (Pinnacle Sector II TM acetabular cup, DePuy Orthopaedics Inc., Warsaw, IN), a highly cross-linked polyethylene liner (AltrX TM polyethylene liner, DePuy Orthopaedics Inc., Warsaw, IN), and a cobalt chrome femoral head (Articul/eze TMcobalt chrome, DePuy Orthopaedics Inc., Warsaw, IN). We prospectively recorded costs of operating room time, length of stay in hospital, and medical and surgical interventions using a micro-costing method. Group comparisons were performed using Pearson's Chi-square and one-way Analysis of Variance (ANOVA), with post-hoc testing when necessary. All costs were reported in 2013 Canadian dollars. Results. One-hundred and eighteen patients (40 anterior, 38 posterior, and 40 lateral) completed the study. All three groups were similar with regards to age (p=0.79), sex (p=0.97), and body mass index (p=0.54). Mean operating room time was significantly shorter for the lateral (49.0 minutes, 95%CI 46.5 – 51.5) versus anterior (69.3 minutes, 95%CI 66.0 – 72.6, p<0.001) and posterior approach (61.6 minutes, 95%CI 57.5 – 65.5, p<0.001). Mean length of stay was shorter for the anterior (33.9 hours, 95%CI 29.6 – 38.2) compared to the posterior (65.8 hours, 95%CI 56.8 – 74.8, p<0.001) and lateral approach (64.2 hours, 95%CI 56.7 – 71.7, p<0.001). The operating room costs were significantly higher for the anterior versus posterior (p=0.008) and lateral approach (p<0.001, figure 1). The total inpatient costs were significantly for the anterior versus posterior and lateral approach (p<0.001 for both pair-wise comparisons, figure 2). Total costs were significantly less for the anterior ($7300.22, 95%CI 7064.49 – 7535.95) versus posterior ($8287.46, 95%CI 7906.41 – 8668.51, p<0.001) and lateral approach ($7853.10, 95%CI 7577.29 – 8128.91, p=0.031). Discussion / Conclusion. Total costs for THA were significantly less when performed using an anterior approach. A reduction in hospital length of stay contributed significantly to an overall reduction in costs from a hospital perspective. Future analyses will determine the cost-effectiveness of the anterior approach from both a hospital and societal perspective

Representative pre-clinical analysis is essential to ensure that novel prosthesis concepts offer an improvement over the state-of-the-art. Proposed designs must, fundamentally, be assessed against cyclic loads representing common daily activities [Bergmann 2001] to ensure that they will withstand conceivable in-vivo loading conditions. Fatigue assessment involves:. –. cyclic mechanical testing, representing worst-case peak loads encountered in-vivo, typically for 10 million cycles, or. –. prediction of peak fatigue stresses using Finite Element (FE) methods, and comparison with the material's endurance limit. Cyclic stresses from gait loading are super-imposed upon residual assembly stresses. In thick walled devices, the residual component is small in comparison to the cyclic component, but in thin section, bone preserving devices, residual assembly stresses may be a multiple of the cyclic stresses, so a different approach to fatigue assessment is required. Modular devices provide intraoperative flexibility with minimal inventories. Components are assembled in surgery with taper interfaces, but resulting residual stresses are variable due to differing assembly forces and potential misalignment or interface contamination. Incorrect assembly can lead to incomplete seating and dissociation [Langdown 2007], or fracture due to excessive press-fit stress or point loading [Hamilton 2010]. Pre-assembly in clean conditions, with reproducible force and alignment, gives close control of assembly stresses. Clinical results indicate that this is only a concern with thick sectioned devices in a small percentage of cases [Hamilton 2010], but it may be critical for thin walled devices. A pre-clinical analysis method is proposed for this new scenario, with a case study example: a thin modular cup featuring a ceramic bearing insert and a Ti-6Al-4V shell (Fig. 1). The design was assessed using FE predictions, and manufacturing variability from tolerances, surface finish effects and residual stresses was assessed, in addition to loading variability, to ensure physical testing is performed at worst case:. –. assembly loads were applied, predicting assembly residual stress, verified by strain gauging, and a range of service loads were superimposed. The predicted worst-case stress conditions were analysed against three ‘constant life’ limits [Gerber, 1874, Goodman 1899, Soderberg 1930], a common aerospace approach, giving predicted safety factors. Finally, equivalent fatigue tests were conducted on ten prototype implants. Taking a worst-case size (thinnest-walled 48 mm inner/58 mm outer), under assembly loading the peak tensile stress in the titanium shell was 274 MPa (Fig. 2). With 5kN superimposed jogging loading, at an extreme 75° inclination, 29 MPa additional tensile stress was predicted. This gave mean fatigue stress of 288.5 MPa and stress amplitude of 14.5 MPa (R=0.9). Against the most conservative infinite life limit (Soderberg), the predicted safety factor was 2.40 for machined material, and 2.03 for forged material, or if a stress-concentrating surface scratch occurs during manufacturing or implantation (Fig. 3). All cups survived 10,000,000 fatigue cycles. This study employed computational modelling and physical testing to verify the strength of a joint prosthesis concept, under worst case static and fatigue loading conditions. The analysis technique represents an improvement in the state of the art where testing standards refer to conventional prostheses; similar methods could be applied to a wide range of novel prosthesis designs

Objective. Sarcomas are a rare group of tumours, which pose numerous problems regarding correct diagnosis and appropriate management. This study aimed to examine whether symptom duration and tumour size at diagnosis have changed over time, using size and symptom duration as methods of comparison. Methods. All patients diagnosed with sarcoma were identified retrospectively from a prospective database from 1963 to 2005. Demographic data concerning age at diagnosis, sex and diagnosis were recorded. Data were also collected on duration of symptoms and size of tumour at diagnosis. Symptom duration is defined as the length of time the patient was experiencing symptoms for until the date of diagnosis. Changes in size and symptom duration over time were compared by grouping date of diagnosis into time periods and comparing them against each other using non-parametric statistical analysis. Results. 4560 met our inclusion and exclusion criteria, with 2492 Bone Sarcomas (BS) and 2068 Soft Tissue Sarcomas (STS). Overall analysis of both BS and STS showed that size at diagnosis has decreased and symptom duration has increased. Analysis of STS showed that size has decreased over time, particularly following the introduction of referral guidelines in 1999 (median size pre 99 = 10cm, post = 8cm, Mann-Whitney-U test p=0.000 to 3 sig. fig.), but symptom duration has remained unaltered over time. Duration of symptoms reported for BS has significantly increased over time; however, size at diagnosis has remained unchanged over time. Conclusions. It appears from this study that STS are being diagnosed more quickly and that this is most likely due to the introduction of specific STS guidelines in 1999. This result is particularly heartening, and should encourage further promotion of such guidelines. Awareness of BS still appears to be low as size at diagnosis remains unchanged over time

Surgeons performing hip resurfacing ante-vert and translate the femoral component anterior to maximize head/neck offset and educe impingement. The anterior femoral neck is under tensile forces during gait similarly to the superior neck [6]. This study was esigned to determine the risk of femoral neck fracture after anterior or posterior notching of the femoral neck. Method: Fortyseven 4th generation synthetic femora were implanted with Birmingham Hip Resurfacing pros-theses (Smith & Nephew Inc. emphis, USA). Implant preparation was performed using imageless computer navigation (VectorVision SR 1.0, BrainLAB, Grmany). The virtual prosthesis was initially planned for neutral version and translated anterior, or posterior, to create the notch. The femora were fixed in a single-leg stance and tested with axial compression using a mechanical testing machine. This method enabled comparison with previously published data. The synthetic femora were prepared in 8 experimental groups:2mm and 5mm anterior notches, 2mm and 5mm posterior notches, neutral alignment with no notching (control), 5mm superior notch, 5mm anterior notch tested with the femur in 25° flexion and 5mm posterior notch tested with the femur in 25° extension We tested the femora flexed at 25° flex-ion to simulate loading as seen during stair ascent. [3] The posterior 5mm notched femoral necks were tested in extension to simulate sporting activities like running. The results were compared to the control group in neutral alignment using a one-way ANOVA:. Results: Testing Group Mean load to failure Significance Neutral (Control) 4303.09 ± 911.04N Anterior 2mm 3926.62 ± 894.17N p=0.985 Anterior 5mm 3374.64 ± 345.65N p=0.379 Posterior 2mm 4208.09 ± 1079.81N p=1.0 Posterior 5mm 3988.07 ± 728.59N p=0.995 Superior 5mm 2423.07 ± 424.16N p=0.003 Anterior 5mm in 25° flexion 3048.11 ±509.24N p=0.087 Posterior 5mm in 25° extension 3104.61±592.67N p=0.117 Both the anterior 5mm notch tested in single-leg stance and anterior notch in flexion displayed lower compressive loads to failure (3374.64N and 3048.11N). The mean load to failure value for the posterior 5mm notches in extension was 3104.62N compared to 4303.09N for the control group. Our data suggests that anterior and posterior 2mm notches are not statistically significantly weaker in axial compression. The anterior 5mm notches tend towards significance in axial compression (p=0.38) and bordered significance in flexion (p=0.087). The 5mm posterior notches were not significantly weakened in axial compression (p=0.995), but tended towards significance in extension (p=0.117). The 5mm superior notch group was significantly weaker with axial compression supporting previous data published (p=0.003). We are currently assessing offset and other variables that may reduce data spread. Conclusion: We conclude that anterior and posterior 2mm notching of the femoral neck has no clinical implications, however 5mm anterior notches may lead to fracture. The fracture is more likely to occur with stair ascent rather than normal walking. Posterior 5mm notches are not likely to fracture with normal gait, but may fracture with higher impact activities that promote weight bearing in extension. Hip resurfacing is commonly performed on active patients and ultimately 5mm notching in the anterior or posterior cortices has clinically important implications

Purpose: Surgeons performing hip resurfacing antevert and translate the femoral component anteriorly to maximize head/neck offset and reduce impingement. The anterior femoral neck is under tensile forces during gait similarly to the superior neck [6]. This study was designed to determine the risk of femoral neck fracture after anterior or posterior notching of the femoral neck. Method: Forty seven fourth generation synthetic femora were implanted with Birmingham Hip Resurfacing prostheses (Smith & Nephew Inc. Memphis, USA). Implant preparation was performed using imageless computer navigation (VectorVision SR 1.0, BrainLAB, Germany). The prosthesis was initially planned for neutral version and translated anterior, or posterior, to create a femoral neck notch. The femora were fixed in a single-leg stance and tested with axial compression using a mechanical testing machine. This method enabled comparison with previously published data. The synthetic femora were prepared in eight experimental groups:two mm and five mm anterior notches, two mm and five mm posterior notches, neutral alignment with no notching (control), five mm superior notch, five mm anterior notch tested with the femur in 25° flexion and five mm posterior notch tested with the femur in 25° extension We tested the femora flexed at 25° flexion to simulate loading as seen during stair ascent. [3] The posterior five mm notched femoral necks were tested in extension to simulate sporting activities like running. The results were compared to the control group in neutral alignment using a one – way ANOVA:. Results: Testing Group Mean load to failure Significance (p-value) Anterior 2mm 3926.61 ± 894.17 .843 Anterior 5mm 3374.64 ± 345.65 .155 Neutral (Control) 4539.44 ± 786.44 – Posterior 2mm 4208.09 ± 1079.81 .994 Posterior 5mm 3988.06 ± 728.59 .902 Superior 5mm 2423.07 ± 424.17 .001 Anterior 5mm in 25° flexion 3048.11 ± 509.24 .027 Posterior 5mm in 25° extension 3104.62 ± 592.67 .038 Our data suggests that anterior and posterior two mm or five mm notches are not significantly weaker in axial compression. Anterior and posterior 5mm notches are significantly weaker in flexion/extension (p=0.027/ p=0.038). The five mm superior notch group was significantly weaker with axial compression supporting previous published data (p=0.001). Conclusion: We conclude that anterior or posterior two mm notching of the femoral neck has no clinical implications, however five mm anterior or posterior femoral neck notching significantly weakens the femoral neck. Fracture is more likely to occur with stair ascent or activities involving weight bearing in extension. Hip resurfacing is commonly performed on active patients and five mm neck notching has clinically important implications

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

We concluded that the DHS blade was the superior implant in this study.