The fidelity of a 3D model created using image segmentation must be precisely quantified and evaluated for the model to be trusted for use in subsequent biomechanical studies such as finite element analysis. The bones within the ankle joint vary significantly in size and shape. The purpose of this study was to test the hypothesis that the accuracy and reliability of a segmented bone geometry is independent of the particular bone being measured. Computed tomography (CT) scan data (slice thickness 1 mm, pixel size 808±7 µm) from three anonymous patients was used for the development of the ankle geometries (consisting of the tibia, fibula, talus, calcaneus, and navicular bones) using Simpleware Scan IP software (Synopsys, Exeter, UK). Each CT scan was segmented 4 times by an inexperienced undergraduate, resulting in a total of 12 geometry assemblies. An experienced researcher segmented each scan once, and this was used as the ‘gold standard’ to quantify the accuracy. The solid bone geometries were imported into CAD software (Inventor 2023, Autodesk, CA, USA) for measurement of the surface area and volume of each bone, and the distances between bones (tibia to talus, talus to navicular, talus to calcaneus, and tibia to fibula) were carried out. The intra-class coefficient (ICC) was used to assess intra-observer reliability. Bland Altman plots were employed as a statistical measure for criteria validity (accuracy) [1].Abstract
Objectives
Methods
This abstract provides an update on the Open Ankle Models being developed at the University of Bath. The goal of this project is to create three fully open-source finite element (FE) ankle models, including bones, ligaments, and cartilages, appropriate musculoskeletal loading and boundary conditions, and heterogeneous material property distribution for a standardised representation of ankle biomechanics and pre-clinical ankle joint analysis. A computed tomography (CT) scan data (pixel size of 0.815 mm, and slice thickness of 1 mm) was used to develop the 3D geometry of the bones (tibia, talus, calcaneus, fibula, and navicular). Each bone was given the properties of a heterogeneous elastic material based on the CT greyscale. The density values for each bone element were calculated using a linear empirical relation, ρ= 0.0405 + (0.000918) HU and then power law equations were utilised to get the Young's Modulus value for each bone element [1]. At the bone junction, a thickness of cartilage ranging from 0.5–1 mm, and was modelled as a linear material (E=10 MPa, ν=0.4 [2]). All ligament insertions and positions were represented by four parallel spring elements, and the ligament stiffness and material attributes were applied in accordance with the published literature [2]. The ankle model was subjected to static loading (balance standing position). Four noded tetrahedral elements were used for the discretization of bones and cartilages. All degrees of freedom were restricted at the proximal ends of the tibia and fibula. The ground reaction forces were applied at the underneath of the calcaneus bone. The interaction between the cartilages and bones was modelled using an augmented contact algorithm with a sliding elastic contact between each cartilage. A tied elastic contact was used between the cartilages and the bone. FEbio 2.1.0 (University of Utah, USA) was used to construct the open-source ankle model.Abstract
Objectives
Methods
The aim of this study was to develop an open-source finite element model of the ankle for identification of the best clinical treatment to restore stability to the ankle after injury. The ankle geometry was defined from the Visible Human Project Female CT dataset available from the National Library of Medicine, and segmented using Dragonfly software (Object Research Systems, 2020). The finite element model was created with FEBio (University of Utah, 2021) using the dynamic nonlinear implicit solver. Linear isotropic material properties were assigned to the bones (E=7300MPa, ν=0.3, ρ=1730kg/m3) and cartilage (E=10MPa, ν=0.4, ρ=1100kg/m3). Spring elements were used to represent the ligaments and material properties were taken from Mondal et al. [1]. Lagrangian contact was defined between the cartilaginous surfaces with μ=0.003. A standing load case was modelled, assuming even distribution of load between the feet. A reaction force of 344.3N was applied to the base of the foot, a muscle force of 252.2N, and the proximal ends of the tibia and fibula were fully constrained.Abstract
Objectives
Methods
In March 2020, the World Health Organisation declared the COVID-19 outbreak a pandemic. Multiple new guidelines were proposed and existing models of social, domestic and hospital care altered. Most healthcare systems were largely unprepared for this and this pandemic has tested their adaptability. This study is aimed at assessing the impact of covid-19 on the demographics, presentation and clinical management of patients with proximal femoral (hip) fractures. This retrospective multi-centre cohort study compared all patients admitted with hip fractures, between 1st March and 30th May 2019 (Group PC: Pre-Covid) with hip fracture patients admitted over the same time period during the pandemic in 2020 (Group C: Covid). The data was obtained from the hospitals' local and National Hip Fracture Databases. Mortality data was checked with the Office for National Statistics (ONS). Primary outcomes were time to theatre, in-patient length of stay and 30-day mortality. 580 patients were included (304 PC, 276 C). Patient Charlson comorbidity index and Nottingham Hip Fracture scores were broadly similar across the two cohorts. There was a significant reduction in percentage of total hip replacements in Group C (11% to 5%, p=0.006). There was an increase in conservative management in group C (1% to 5%, p=0.002). The time to theatre was significantly delayed in Group C (43.7 hours C versus 34.6 hours PC, p<0.001). Overall length of hospital stay was similar in both groups (16.6 days PC versus 15 days C, p=0.089). 30-day mortality rate in Group C was 9.8% compared to 8.2% in Group PC (p=0.431), but for covid (+) patients it was significantly higher at 38.2% versus 5.8% in covid (−) patients (p<0.001). This is one of the largest multi-centre comparative cohort study in the literature to date, examining the impact of the covid-19 pandemic on the management of hip fracture patients. Whilst mortality rates were similar in both groups, covid patients were almost seven times more likely to die, reflecting the seriousness of the covid-19 infection and its sequelae in such elderly, vulnerable patients.
Hindfoot surgery is assumed to be more painful than midfoot/forefoot procedures with the former often requiring an inpatient stay for pain relief. Poorly controlled pain is associated with adverse patient outcomes and consequently, peripheral nerve blocks (PNB) have become popular for their effective pain control. To investigate whether hindfoot procedures are more painful than forefoot/midfoot procedures by measuring pain scores, assessing effectiveness of PNBs and patient satisfaction in foot and ankle surgery.Introduction
Aim
Our aim in this paper was to investigate the
guidelines and laws governing informed consent in the English-speaking
world. We noted a recent divergence from medical paternalism within
the United Kingdom, highlighted by the Montgomery v Lanarkshire Health
Board ruling of 2015. We investigated the situation in the United
Kingdom, Australia, New Zealand, Canada, and the United States of
America. We read the national guidance regarding obtaining consent
for surgical intervention for each country. We used the references
from this guidance to identify the laws that helped inform the guidance,
and reviewed the court documents for each case. There has been a trend towards a more patient-focused approach
in consent in each country. Surgeons should be aware of the guidance
and legal cases so that they can inform patients fully, and prevent
legal problems if outdated practices are followed. Cite this article:
To determine the influence of tendo achilles (TA) rupture gap distance and location on clinical outcome managed with accelerated functional rehabilitation. Twenty six patients with acute complete TA ruptures underwent ultrasound (US) within a week of injury. Measurements included the distance of the rupture from the enthesis and the gap distance between the tendon edges in three positions – foot plantigrade, maximum equinus and maximum equinus with 90o knee flexion. All patients were managed non-operatively in functional weightbearing orthoses. Nineteen patients were followed up at a mean of 6.1 years (range 5.8–6.5). Outcomes included ultrasound confirmation of healing, Achilles Tendon Rupture Score (ATRS) and Modified Lepilahti score (MLS).Aim
Methods
Bowel management following joint replacement is often neglected leading lot of patient distress, with the advent of the enhanced orthopedic rehabilitation program, there is a need of a guideline to ensure prompt and quick recovery of bowel habits before discharge. Our aim was to identify the incidence of constipation in joint replacement patients, to evaluate the current practice of bowel management and formulate a protocol for management of constipation to improve the practice. We conducted a prospective study of 50 patients who underwent joint replacement procedures at our institute between September and October 2015. Following initial audit, we formulated a protocol for bowel management, and performed a re-audit by collecting a prospective data of 50 patients. The statistical analysis was done and calculating the mean and standard deviation for continuous variable and Fischer's exact test was used and significance level was set at 0.05. Incidence of constipation was 88% and laxatives were prescribed in 42%. More importantly, there was no correlation between constipation and pre operative fasting (p Value 0.33), post operative fasting (p Value 0.1822), type of surgery (p value 1.00) and type of anaesthesia (p Value 0.27). Following introduction of bowel protocol the laxative prescription increased to 98% (Prophylactic in 81%), consequently the incidence of constipation reduced to 18%. Implementing bowel protocol significantly will improve the patient care and reduce the rate of complications.
The Exeter femoral stem is a double-tapered highly
polished collarless cemented implant with good long-term clinical
results. In order to determine why the stem functions well we have
undertaken a long-term radiostereometric analysis (RSA) study. A total of 20 patients undergoing primary Exeter total hip replacement
for osteoarthritis using the Hardinge approach were recruited and
followed with RSA for ten years. The stems progressively subsided
and internally rotated with posterior head migration. The mean subsidence
was 0.7 mm (95% confidence interval (CI) 0.5 to 0.9) at two years
and 1.3 mm (95% CI 1.0 to 1.6) at ten years. The mean posterior
migration of the head was 0.7 mm (95% CI 0.5 to 0.9) at two years
and 1.2 mm (95% CI 1.0 to 1.4) at ten years. There was no significant
cement restrictor migration. The Exeter stem continues to subside slowly into the cement mantle
in the long term. This appears to compress the cement and the cement
bone interface, contributing to secure fixation in the long term. Cite this article:
Achilles tendinosis results from a chronic degenerative process within the tendon. Topaz micro-debridement aims to restore the degenerate micro-architecture within the tendon reducing painful symptoms experienced by patients. Topaz micro-debridement has been used to successfully treat upper limb tendinopathies but its application to tendinopathies of the foot and ankle is relatively new. This study aims to assess the functional outcomes following topaz radiofrequency micro-debridement for Achilles tendinosis. All cases of topaz micro-debridement for Achilles tendinosis were identified from hospital records spanning a five year period. VISA-A assessment questionnaires were sent to these patients to assess the patients functional status pre and post-surgery. Patients were asked to comment on their overall satisfaction and to report any complications they had experienced. Eight responses were received and included in analysis. Hospital records and imaging results were investigated for those that responded.Introduction
Materials/Methods
Venous thromboembolism (VTE) is a significant cause of patient morbidity and mortality, the risk of which increases in orthopaedic patients with lower limb immobilisation. This incidence should in theory reduce if the patients are ambulatory early in the treatment phase. The aim of this study was, therefore, to identify a difference in the incidence of symptomatic VTE by treating acute Achilles tendon rupture patients with conventional non-weight bearing plaster versus functional weight bearing mobilisation. The notes of 91 consecutive patients with acute Achilles tendon rupture were retrospectively reviewed and prospectively followed. The patients' demographics, treatment modality (non-weight bearing plaster versus weight bearing boot), and the type of plaster immobilisation was compared to assess whether they affect the incidence of clinical VTE. The predisposing risk factors were also analysed between the treatment groups. Out of 91 patients, 50 patients with acute Achilles tendon rupture were treated conservatively in a conventional non-weight bearing immobilisation cast. From these 50 patients, 3 then underwent surgery and were therefore excluded from the results. On the other hand, 41 patients were treated with functional weight bearing mobilisation (Vacupad). Patients who did have a symptomatic thromboembolic event also had an ultrasound scan to confirm a deep vein thrombosis of the lower limb or a CT-scan to confirm pulmonary embolism.Introduction
Methodology
Thromboembolism is a significant cause of patient morbidity and mortality, the risk of which increases in orthopaedic patients with lower limb immobilisation. It was therefore, our aim to identify a difference in symptomatic thromboembolism by treating acute Achilles tendon rupture patients with conventional non-weight bearing plaster versus functional weight bearing mobilisation. The notes of 91 consecutive patients with acute Achilles tendon rupture were reviewed. The patients demographics, treatment modality (non-weight bearing plaster versus weight bearing boot), and predisposing risk factors were analysed. From the 91 patients, 50 patients with acute Achilles tendon rupture were treated conservatively in a non-weight bearing immobilisation cast. From these 50 patients, 3 then underwent surgery and were therefore excluded from the results. 41 patients were treated with functional weight bearing mobilisation. Patients who did have a symptomatic thromboembolic event had an ultrasound scan to confirm a deep vein thrombosis of the lower limb, or a CT-scan to confirm pulmonary embolism.Introduction/Aim
Methodology
Establishing a full-thickness cartilage in the lateral compartment and functionally intact ACL is vital before proceeding with unicompartmental knee replacement (UKR). The aim of this study is to assess whether MRI is a useful adjunct in predicting suitability for UKR, as compared to standard and stress radiographs. We identified 50 patients with a knee found suitable for UKR based on their standard and stress radiographs (full-thickness cartilage on lateral side). These patients underwent an additional cartilage-specific MRI scan to identify the status of ACL and the lateral compartment. The final decision regarding the suitability for UKR was based on the intra-operative observation.INTRODUCTION
METHODS
The aim of this study was to assess the financial implications of managing skeletal metastases in a tertiary hospital and explore its impact on the provision of acute care trauma services. We identified 47 patients, surgically treated for skeletal metastases over one-year period. Data were collected on demographics, primary tumour, the bone involved, surgery performed, the type of prosthesis used, length of surgery, hospital stay and the exact indication for orthopaedic intervention. The cost incurred was calculated from the cost of the prosthesis implanted, the number of theatre-sessions utilised and the number of inpatient hospital days.Aim
Methods
Mobile bearing unicompartmental knee replacement (UKR) is an accepted treatment for patients with isolated medial unicompartmental knee osteoarthritis (OA) with a full thickness cartilage loss. The aim of this study was to determine if this recommendation was correct and if the procedure could be used for partial-thickness cartilage loss. 1053 Oxford medial UKRs were studied prospectively. The knees were divided into two groups; partial-thickness cartilage loss (PTCL) group and the full thickness-cartilage loss (FTCL) group. The primary outcome measure was the total Oxford Knee Score (OKS, 0 to 48) at the time of final follow up. The groups were also compared for the change in OKS (?OKS) and the proportion of patients that were considered to have benefited substantially from surgery (?OKS >5).INTRODUCTION
METHODS
Roentgen Stereophotogrammetric Analysis (RSA) can predict long-term outcome of prostheses by measuring migration over time. The Exeter femoral stem is a double-tapered highly polished implant and has been shown to subside within the cement mantle in 2 year RSA studies. It has a proven track record in terms of long-term survivorship and low revision rates. Several studies have demonstrated excellent clinical outcomes following its implantation but this is the first study to assess stem migration at 10 years, using RSA. This is a single-centre study involving 20 patients (mean age: 63 years, SD=7) undergoing primary total hip replacement for degenerative osteoarthritis using the lateral (Hardinge) approach. RSA radiographs were taken with the patient bearing full weight post-operatively, at 3, 6, 12 months and at 2, 5 and 10 years follow-up. The three-dimensional migration of the Exeter femoral stem was determined. The mean Oxford Hip Score at 10 years was 43.4 (SD=4.6) and there were no revisions. The stems subsided and rotated internally during a 10-year period. The mean migrations of the head and tip of the femoral stem in all three anatomic directions (antero-posterior, medio-lateral &
supero-distal) were 0.69 mm posterior, 0.04 mm lateral and 1.67 mm distal for the head and 0.20 mm anterior, 0.02 mm lateral and 1.23 mm distal for the tip. The total migration at 10 years was 1.81 mm for the head and 1.25 mm for the tip. The Exeter femoral stem exhibits migration which is a complex combination of translation and rotation in three dimensions. Comparing our 10 year with our previous 2 year migration results, the Exeter stems show continued, but slow distal migration and internal rotation. The subsidence continues to compress the cement and bone-cement interface which maintains secure fixation in the long term.
100% of medial compartments showed full thickness anteromedial loss with preservation of the posteromedial cartilage. When present, the meniscus was extruded in 96% of cases. 90% of lateral compartments were normal and none had full thickness cartilage loss. However 10% showed high signal in the tibial plateau. There was a highly reproducible pattern of osteophyte formation; 94% posteromedial and posterolateral aspect of medial femoral condyle; 90% medial tibial; 80% medial femoral and 84% lateral intercondylar notch.
Kinematic data from in-vivo fluoroscopy measurements during a step-up activity was used to determine the relative tibial-femoral position as a function of knee flexion angle for each model. Medial and lateral force distribution was adapted from loads measured in-vivo with an instrumented implant during a step-up activity. The affect that varying the bearing thickness has on the stresses in the bearing was investigated. In addition, varus-valgus mal-alignment was investigated by rotating the femoral component through 10 degrees.
Tibial lesion: In lateral OA, the midpoint of lesions was 2.0mm (SD:6.5) posterior to the reference line passing through the mid-coronal plane of the resected tibia. This was located significantly more posterior (p=0.038) than midpoint in medial OA, which was 2.2mm (SD:5.7) anterior to the reference line. Knee Flexion Angle: In lateral OA, the midpoint of lesions was on average at 40° flexion and sites of smaller lesions were very variable. The lesion expanded both anteriorly and posteriorly. In medial OA, smaller femoral lesions occurred in full extension and extended further posteriorly with disease progression. No significant difference was demonstrated in medial and lateral localisation of the lesions.
This study demonstrates that medial overhang of less than three millimetres for the tibial component is acceptable in the Oxford UKA. Excessive overhang equal to this or more results in significantly worse ΔOKS and ΔPS. However, no difference in the five year ΔOKS and ΔPS was demonstrated between underhang and the other two groups in this study.
