BOA Annual Congress 2025

Biomechanical assessment of bone loss in transfemoral and knee disarticulation amputees

Louise McMenemy 1,4,5, Linjie Wang 2,4, Alison H. McGregor 3,4, Andrew T. M. Philips 2,4
1. Academic Department of Military Surgery and Trauma, RCDM, Birmingham, UK; 2. Structural Biomechanics, Department of Civil and Environmental Engineering, Imperial College London, UK; 3. Department of Surgery and Cancer, Imperial College London, UK; 4. Centre for Injury Studies, Imperial College London, UK. 5. Institute of Naval Medicine, Gosport, UK

Aims:
Bone mineral density (BMD) reduction in amputees risks stress and fragility fractures potentially preventing the wearing of prostheses and hence reducing mobility. BMD loss occurs in military veteran amputees predominantly in the amputated side neck of femur [1], with transfemoral amputees most severely affected. BMD reduction is not systemic; therefore we propose this change is due to reduced mechanical stimulation. To assess this, we used a computational modelling framework to compare the mechanical stimulation of the femur for a body matched control subject (CS), transfemoral amputee (TFA), and knee disarticulation amputee (KDA).

Methods:
Musculoskeletal models were developed and used with motion capture data to derive joint contact and muscle forces for walking, stair-ascent and stair-descent, sit-to-stand and stand-to-sit. Corresponding finite element models were developed and forces used as input, with the resulting mechanical stimulus (strain) in the femur compared between subjects. Bone adaptation simulations were run using a strain-based algorithm [2].

Results:
Compared to CS, BMD reduction of 32% for TFA and 8% for KDA was predicted in the proximal femur. For CS stair-ascent and stair-descent provided the highest level of stimulation. For TFA reduced stimulation was observed for all activities, while for KDA stair-descent provided stimulation close to that for CS. Both amputees descended stairs using a reciprocal motion and ascended using a non-reciprocal motion. Both amputees favoured their intact leg in sit-to-stand and stand-to-sit. Maximum hip joint contact force (HJCF) was similar between CS and both amputees, suggesting HJCF is not a suitable proxy indicator of bone health.

Conclusions:
Physiological load transfer was not achieved between prosthetic socket and distal femur for either amputee. Retention of the cortex in KDA resulted in a more physiological mechanical environment in the proximal femur than in TFA, suggesting knee disarticulation compared to femoral resection is beneficial for maintaining bone health.
[1] McMenemy L et al., J Bone Miner Res, 38:1227-1233, 2023.
[2] Villette and Phillips, PLoS One, 19(4): e0297932, 2024

Mini-open Achilles Repair: 100 patient case series using the Achillon system
Author:  Emily Cartwright, Carys Brown, Matthew Morris, Jonathan May

Background

Achillon is a minimally invasive system for tendo-achilles repair used in our trust for all acute repairs. A retrospective analysis was performed on prospectively collected data for 100 consecutive patients with minimum follow up of 6 months from 2020 to 2024 from a single-centre district general hospital in England.  All repairs were performed with a Foot and Ankle consultant present under tourniquet and all followed the same post operative rehabilitation protocol.

Results:

The demographic had an average age of 41, predominantly men and with an average tourniquet time of 29 minutes.  There were no immediate or delayed sural nerve injuries.  Our DVT rate was 2% and 1% healed in a lengthened position requiring re-operation (in a non-compliant individual). There were no re-ruptures and no superficial or deep infections.  Successful rehabilitation was achieved in 99% of patients; they were either satisfied or very satisfied based on physiotherapy reports and clinic letters.  Furthermore a basic cost and NHS resource assessment was carried out – examining the cost in terms of the purchase of the Achillon jigs, operative materials, theatre time, appointments and post operative footwear (boot with wedges).

This case series represents one of the largest reported and adds to the growing body of evidence currently published.  It identifies resources needed to deliver an acute operative tendo-achilles treatment protocol with a low complication rate and a high success rate within an NHS district general hospital setting.

Nail Plate Construct in Complex Distal Femur Fractures allow safe, early unrestricted weight bearing with high rates of union and a low rate of failure: five-year experience at a UK Major Trauma Centre

Authors and Affiliations

Tom Barrow MBBS, BSc, PGCert, MRCS,¹ Orthopaedic Registrar, Anthony Rayner MBBS, BSc, MRCS,¹ Orthopaedic Registrar, David Crone MBBS, FRCS (Tr&Orth), MIoL¹, Trauma & Orthopaedic Consultant, Enis Guryel MBBS, BSc, FRCS (Tr&Orth)¹, Trauma & Orthopaedic Consultant, Simon Francis Bellringer MBBS, BSc, FRCS (Tr&Orth), FEBHS,¹ Trauma & Orthopaedic Consultant, Alastair Robertson MBBS, BSc, FRCS (Tr&Orth),¹ Trauma & Orthopaedic Consultant, 1 – Department of Trauma and Orthopaedics, University Hospitals Sussex, Brighton, UK

Abstract

Aims: Distal femur fractures can be challenging to manage and fixation with either intramedullary nails or plates can result in failure of fixation. The use of linked nail plate constructs (NPC) has gained popularity for managing complex distal femur fractures. The five-year’s experience from a UK major trauma centre is reported and aims to identify appropriate indications and describe patient outcomes.

Methods: Patients treated for a distal femoral fracture with a NPC between 1^st January 2019 and 1^st January 2025 were identified. Patient demographics, fracture classification, procedural characteristics, post operative weight-bearing status, union rates, complications and mortality were recorded.

Results: 32 patients were identified with a mean age of 70 years (20 to 98). 24 patients were female (75%) with a median ASA of 3. There were 5 open fractures (16%) and 10 peri-prosthetic fractures (31%). 8 NPCs were revision operations following failure of primary fixation (25%). All operations were performed by at least one consultant. In total 31 patients were permitted unrestricted weight bearing post-operatively (97%). Clinical union was achieved in 24 of 25 patients available for follow up (96%). There were no significant complications. Mortality rate at 30-days, 3-months and 12-months was 6%, 6% and 13% respectively.

Conclusions: This study supports the use of nail plate construct (NPC) in the management of both primary and revision surgery for complex distal femoral fractures. Among 32 patients with a mean age of 70 years, NPC permitted immediate unrestricted weight bearing (97%) with a high rate of union (96%) and a low complication and mortality rates. These findings highlight NPC as an effective option for managing complex distal femur fractures.

PREDICTING PATIENT REPORTED OUTCOME MEASURES FOLLOWING HIP AND KNEE ARTHROPLASTY USING SUPERVISED MACHINE LEARNING

Authors: Samantha Davies, Amr Selim, Andrew Roberts, Geraint Thomas, Paul Cool

Introduction
The role of machine learning (ML) in orthopaedics is expanding, with potential applications in analysing patient data and making predictive assessments. This project utilised NHS PROMs data from primary hip and knee replacements to identify key trends and assess whether this data can reliably predict recovery rates based on patient-reported outcomes and comorbidities.

Methods
The study used the NHS England national PROMs dataset for the 2018/2019 financial year, comprising 37,725 primary hip replacement entries and 43,639 primary knee replacement entries, each containing 139 variables. Key outcome measures included the Oxford Hip Score (OHS), Oxford Knee Score (OKS), EQ5D-3L, and EQ5D-Visual Analogue Scale (VAS). Python, with the scikit-learn (sklearn) library, was used to program and develop the ML models. Three supervised ML algorithms—Stochastic Gradient Descent (SGD), Classification and Regression Trees (CART), and Support Vector Machines (SVMs)—were tested independently.

Results
For primary hip replacements, the accuracy scores showed that SGD achieved 70%, CART 68%, and SVM 48%, while for knee replacements, SGD achieved 65%, CART 67%, and SVM 54%.

The ROC-AUC analysis further indicated AUC values for hip replacements as 0.72 for SGD, 0.70 for CART, and 0.59 for SVM. While for knee replacements AUC was 0.59 for SGD, 0.68 for CART, and 0.52 for SVM.

In precision-recall analysis, the average precision scores were 0.89 for hips and 0.79 for knees with SGD, 0.88 for hips and 0.84 for knees with CART, and 0.82 for hips and 0.74 for knees with SVM.

Interestingly, feature importance analysis revealed that preoperative anxiety and depression had the highest feature importance score (28.1) for predicting postoperative knee scores, whereas preoperative disability had the highest feature importance score (5.8) for predicting postoperative hip replacement scores.

Conclusion
ML models showed higher predictive accuracy for primary hip replacements compared to knee replacements. While this study demonstrates the potential of ML for predicting patient-reported outcomes, limitations in the reliability of current national PROMs data hinder its broader application. The lack of data validation within the national dataset raises concerns about accuracy, making it difficult to fully trust the model’s predictions without verification from individual organizations.

Epidemiology and survivorship of primary knee arthroplasty in young adults: analysis of 3069 cases from the Scottish Arthroplasty Project

Author: Scott R Morrison, Andrew J Hall, Jon V Clarke, Andrew Brunt, Muhammad Adeel Akhtar, Phil Walmsley

Background

There is a lack of information regarding survivorship and epidemiology in young adult patients undergoing primary knee arthroplasty (KA), despite increasing case load. This study aimed to evaluate the epidemiology of young adult patients undergoing KA and assess implant survivorship and revision risk.

Method

Retrospective review of prospectively collected national registry data from the Scottish Arthroplasty Project database evaluated patients aged 16 – 49 undergoing primary KA between January 2000 and December 2019. Data were analysed using SPSS.

Results

There were 3069 patients, 58.6% were female, mean age was 44 years, and median follow-up duration was 8 years. 79.6% of procedures were for osteoarthritis, with non-osteoarthritis causes more common in patients aged <35 years. 8.3% of cases required revision throughout the follow-up period, with the cumulative revision rate at 21 years being 14.2%. Lifetime revision risk for the cohort was estimated at 38.3%. Revision rate was lowest for patients aged <25 years and highest for those aged 40 – 44 years (3.1% vs 9.6%). Total mortality rate was 6.2%, which is greater than the age-adjusted general population mortality rate of 4.6%; the mortality rate was 4.7% in patients undergoing KA for osteoarthritis, versus 12.2% in non-osteoarthritis cases.

Conclusion

Revision risk for patients aged <50 years is greater than for those aged ≥50 years. Overall mortality was higher than in the general population; accounted for by an increased mortality in the non-osteoarthritis arthroplasty group. Revision risk remains high for younger patients, but specific groups appear at higher risk than others.

The cost of implant waste in trauma orthopaedic surgery and sustainability considerations: an observational study
Author: Rasi Mizori, Fizza Ali, Muhayman Sadiq, Yasser Al Omran, Thomas Lewis, Omar Musbahi & Karthik Karuppaiah 

Purpose

Implant wastage in trauma and orthopaedic (T&O) surgery remains an under-reported yet significant issue, contributing to rising healthcare costs and environmental concerns. With increasing surgical demand driven by an ageing population and the growing prevalence of conditions like osteoporosis, this study aimed to quantify implant wastage in T&O procedures at a Level 1 Major Trauma Centre in London, assessing both its frequency and financial impact.

Methods

A retrospective cohort study was conducted on all weekday T&O procedures performed between 1st December 2023 and 31st January 2024. Two of the authors identified wasted implants using intraoperative implant logbooks, and cross-referencing implant stickers with post-operative radiographs. Data pertaining to patient demographics, procedure types, surgical sites, and implant usage were collected. Cost analysis was performed using procurement data to determine the financial impact of implant wastage.

Results

Among 184 procedures analysed, 131 (71.2%) used implants, with wastage observed in 108 (82.4%) cases. A total of 141 implants were wasted, with screws accounting for 92.9% (n = 131) of wasted implants. Locking screws were the most frequently discarded (n = 65; 46.1%). Across ORIF and intramedullary nailing procedures, an overall screw wastage rate of 20% (17–31%) was observed with 2.4 screws wasted per trauma procedure. The financial cost of implant wastage over the 44-day study period amounted to approximately £335 per day and £136 per case.

Conclusion

This study highlights the substantial economic burden associated with implant wastage in T&O surgery, with screws, particularly locking screws, being the primary contributors. Targeted interventions, including improved preoperative planning, precision-based implant selection, and enhanced intraoperative decision-making, are essential to reducing waste and improving cost-efficiency and sustainability in surgical practices. Further research should explore the broader economic and environmental impact of implant wastage, incorporating factors such as operative time and carbon footprint to develop comprehensive waste-reduction strategies.

Functional ultrasound assessment of Flexor Pollicis Longus (FPL) tendon to distal radius watershed line distance - variability amongst healthy participants. 

Authors: Jonathan Cormack, Zakaryia Abdulazeez, Reem Bedir, Adrian Chojnowski

Aim:

To use ultrasound to measure the distance between FPL tendon and watershed line of the distal radius, in functional positions of healthy participants, to inform radiology protocols investigating tendon irritation post distal radius volar plate fixation and identify patients at higher risk of injury.

Methods:

The ultrasound assessment of distance was performed by a consultant musculoskeletal radiologist in; 30o flexion, neutral and 30o extension. Function included pincer grips of 0/2/4kg. Preliminary data was limited to 6 healthy wrists aged 20-30 years, producing 42 data points. 

Results:

In neutral, 4kg pincer grip produced the shortest distances (mean; 1.08mm), compared to 0kg (1.2mm). 2kg conversely increased distances (1.3mm).

In extension, any grip shortened distances (4kg 0.86mm; 2kg 1.0mm), compared to 0kg (1.12mm).

Unlike neutral and extension positions, in flexion, any grip increased distances (4kg 6.35mm; 2kg 5.35mm), compared to 0kg (2.45mm).

Conclusions:

The results suggest that the FPL tendon is in closest proximity and most at risk in extended grip positions. Preliminary data suggests variability of tendon position with wrist position and pincer grip pressure.

The post-operative management of distal radius volar locking plates is controversial; from routine removal to ultrasound guided decision making in case tendon complications develop. However, ultrasound assessment can provide false reassurance. Indeed, the authors note case studies of FPL tendon rupture after normal ultrasound studies. Therefore, a clinically accurate, consistent and reproducible protocol is needed to measure the distance between FPL tendon and watershed line of the distal radius under various wrist positions and pincer grip pressures.

Evaluation of X-Ray PPE for Orthopaedic Surgeons in TheatrE (EXPOSEd) Study: A National Survey of Trauma and Orthopaedic Surgeons

Authors: S Donoghue, C Miller, K Chui, H Sevenoaks, D Eastwood

Aims:
To evaluate the accessibility and utility of current radiation personal protective equipment (PPE) provision and understand the experiences and radiation protection practises offered to all levels of Trauma and Orthopaedic (T&O) surgeons in the United Kingdom.

Methods:
An incentivised electronic survey was sent to all UK T&O Surgeons during a 6-week period in 2024.  Responses to 27 multiple-choice questions were collected and free-text responses analysed by theme.

Results:
677 responses from 196 UK NHS Hospitals were received: 33% were female. 67.2% were resident doctors and 32.8% were consultants representing a response rate of 39% for trainees and 11% for consultants. 25% agreed they could find appropriate lead gown PPE. 12% had been given dosimeters, although few had received feedback. 26% received mandatory training but many more (48%) had sought training individually. When undertaken, it was felt useful. Symptoms attributed to ill-fitting PPE were common and more likely to be reported by women (OR 2.5). 55% did not feel protected by their current PPE and 84% were concerned about the effects of IR on their health. Thematic analysis confirmed concerns relating to PPE availability, education, and inconsistent advice and guidance across hospitals. Health concerns and poor morale were also highlighted.

Conclusion:
Employers must address the lack of compliance with the UK legislation Ionising Radiations Regulations 2017 (IRR17) in relation to access to PPE, training and monitoring.  There is a need for standardised national guidelines and training.

Clinical Relevance:

• The current T&O workforce is concerned about both the perceived and real lack of relevant information concerning radiation risk in the workplace, PPE availability and appropriateness.
• These factors discourage doctors from entering our profession and leave those in the profession feeling unsafe.

Outcomes of Robotic Total Hip Arthroplasty for Atypical Hip Anatomy:  Component Positioning, Functional Outcomes, Survivorship and Complications in 192 cases

B Kayani¹, J Enson*¹, J Donaldson¹, J Miles¹, S Newman¹, C Jayadev¹, J Stammers¹, JA Skinner¹

1. Royal National Orthopaedic Hospital, Brockley Hill, Stanmore HA7 4LP

Background:
The objectives of this study were to determine the accuracy of component positioning, patient satisfaction, functional outcomes, component survivorship, and complications of robotic-arm assisted total hip arthroplasty (RO THA) in patients with atypical hip anatomy.

Methods:
This study included 192 RO THAs performed in 182 patients for developmental dysplasia of the hip (n=122), Leg-Calve-Perthes disease (n=27), slipped capital femoral epiphysis (n=20), previous acetabular fracture (n=12), and skeletal dysplasia (n=11). Predefined radiological outcomes, patient satisfaction scores, the University of California at Los Angeles (UCLA) activity score, the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), the Oxford Hip Score (OHS), the Forgotten Joint Score (FJS), and any complications were recorded. The mean follow-up was 3.8 ± 1.7 years (range, 2.1 to 5.4 years).

Results:
RO THA was associated with high accuracy in executing the planned horizontal (root mean square error (RMSE): 1.5 ± 1.4 mm) and vertical centres of rotation (RMSE: 1.8 ± 1.7 mm), combined offset (RMSE: 2.9 ± 3.8 mm), and leg-length correction (RMSE: 1.5 ± 1.4 mm). Acetabular component positioning within Lewinnek’s safe zones was 94.7%, and within Callanan’s safe zones was 93.8%. The median patient satisfaction score was 90 (IQR, 85 to 95), median WOMAC score was 18 (IQR, 12 to 20), and mean FJS score was 77.8 ± 10.8 at final follow-up. RO THA was associated with improvements in the mean UCLA (P < 0.001) and OHS (P < 0.001) at final follow-up. Five-year survivorship was 98.8% (95% CI: 95.8% to 100%) with implant revision for any reason as the end point.

Conclusions:
RO THA in patients with atypical hip anatomy was associated with high accuracy in executing the planned hip biomechanics and acetabular component positioning. In this challenging patient population, RO THA was associated with excellent component survivorship, high patient satisfaction, good functional outcomes, and low risk of complications at short-term follow-up.

Predicting the survival of Meniscal Allograft Transplants – a multi-centre cohort study

Authors – Dylan Mistry, Faizan Arshad, Nicholas Smith, Tim Spalding

Background

Meniscus deficit knees do not benefit from the functions of the meniscus such as load distribution and chondroprotection. Meniscal allograft transplant (MAT) is a novel surgical management option and the MRI appearance in Meniscal Transplant Score (MIMS) is a validated tool for MAT health, scored out of 11. This study aimed to evaluate whether MIMS were predictive of patient related outcome measures (PROMS) or failure rate.

Methods

A retrospective study was carried out on a prospectively collected database of MAT patients in multiple centres. MIMS scores, relative percentage extrusion (RPE) and cartilage grading were judged based on an MRI scan taken one year post-operatively. Regression analysis and survival analysis were then used to predict the improvement in PROMS data from pre-operatively levels (KOOS 4 taken at year 1, 2, 3, 5, 10) and survival of the MAT.

Results

Of the 218 MAT patients with a mean follow up of 4.95 years, mean MIMS score was 6.87 (1–11) and RPE 36% (0-100). Mean improvement in KOOS 4 score was 21.2 (-34–79.5) pre- and post-operatively. As part of regression analysis, MIMS was shown to predict an improvement in KOOS 4 scores (p=0.002) but RPE was not significant (p=0.096). Fifteen patients experienced failure of their MAT, at a mean time of 3.65 years. Both MIMS and RPE were able to predict failure (p=0.007 and 0.004 respectively), as did survival analysis when splitting the cohort with a MIMS score ³6 or <6 (p=0.005), but cartilage grading did not.

Conclusion

This study is the first to our knowledge to compare a recognised MAT assessment tool to PROMS. This gives clinicians treating patients with a MAT the ability to predict the likely success and survival of the transplant based on the MRI findings at 1 year post-operatively.

The impact of co-locating Orthoplastic services at a major trauma centre on the management of Gustilo-Anderson grade IIIB and IIIC tibial fractures

Authors: Matthew Flintoft-Burt, Olivia Morgan, Matthew Towner, Nicholas Hancock
University Hospital Southampton

Background:
This study aims to investigate the outcomes of open tibial fractures following a regional restructuring from offsite plastic surgery cover to a singlecentre Orthoplastics service within a major trauma centre (MTC).

Methods:
Gustilo-Anderson grade IIIB and IIIC open tibial fractures presenting to the MTC from September 2012 to April 2018, and January 2019 to December 2023, were reviewed as pre- and post-restructuring groups. Demographics, injury mechanisms, and treatment details were recorded. Primary outcomes including time to initial debridement and definitive cover, rates of superficial and deep infection, non-union, and amputation were recorded.

Results: 1
16 verses 91 fractures were identified in each group respectively. Mean follow-up was 46 verses 35 months. 95% verses 83% were grade IIIB, 5% verses 16% were grade IIIC. The mean hours to initial debridement were 11.3 verses 12.8, and definitive soft-tissue cover was achieved in 9.9 verses 9.8 days. 14% verses 20% achieved definitive fixation and soft-tissue cover within 72 hours. Outcomes were: superficial infection; 36% and 9%, deep infection; 12% and 8%, non-union requiring revision; 19% and 11%, early amputation; 9.5% and 28%, late amputation; 8.6% and 5%.

Conclusion: Implementing a single-centre Orthoplastics service improved the percentage of patients receiving definitive cover within 72 hours, and lower rates of superficial and deep infection and were observed. A higher number of primary amputations were performed, potentially due to increased early decision-making, with reduced late amputations. This study shows improved outcomes, but numerous clinical and logistical challenges remain. 

Impact of Cryotherapy on Discharge Rates and Pain Management Following Knee Arthroplasty

P Zace¹, Y Roy², O Bailey¹, R Bhattacharrya¹, G Hopper¹ ¹NHS Lanarkshire, ²University of Glasgow