BOA Annual Congress 2026

Title
Fixed- Bearing Unicompartmental Knee Arthoplasty: The Super Heavyweight Champion

Jason Jia Shyan Ong1, Francisco Barbosa1, Navjot Bhangoo1, Robert Straw1, Guido Geutjens1 

Affiliation
1University Hospitals Derby & Burton Foundation Trust, Uttoxeter Road, Derby DE22 3NE 

Abstract 

Background
Morbid obesity (body mass index [BMI] ≥40 kg/m²) is increasingly prevalent among patients undergoing knee arthroplasty. Although unicompartmental knee arthroplasty (UKA) offers functional advantages and outcomes comparable to those in non-obese and class I obese patients, its use in class III morbidly obese individuals remains controversial. Many surgeons continue to regard severe obesity as a relative or absolute contraindication, and evidence evaluating outcomes in this population remains limited. This study aimed to evaluate implant survivorship, revision rates, complications, and functional recovery following fixed-bearing medial UKA in patients with BMI ≥40 kg/m². 

Methods
A single-centre, retrospective cohort study was conducted on 135 consecutive UKA procedures undertaken in patients with BMI ≥ 40 kg/m² between January 2015 and December 2025. Mobile-bearing, lateral compartment, and patellofemoral UKA were excluded. The final cohort comprised 114 fixed-bearing medial UKA. Implant survivorship was analysed using Kaplan–Meier survival analysis with revision for any reason as the endpoint. Restricted mean survival time (RMST) was calculated. Secondary outcomes included postoperative complications and range of motion (ROM). 

Results
The mean age was 59.8 ± 9.0 years, and mean BMI was 43.5 ± 4.6 kg/m². Median follow-up was 5.8 years (95% CI 5.2–6.4), with a maximum follow-up of 10.8 years. Kaplan–Meier analysis demonstrated 5-year implant survivorship of 96.7% (95% CI 93.0–100%). RMST to 5 years was 4.91 years. Three knees (2.6%) underwent revision, including one conversion to total knee arthroplasty for progressive osteoarthritis and two revisions for infection. Four postoperative complications (3.5%) occurred within 90 days. Improvement in postoperative ROM was observed in 86.2% of knees, with correction of all pre-operative fixed flexion deformities. 

Conclusion
Fixed-bearing medial UKA in patients with BMI ≥40 kg/m² demonstrated excellent mid-term survivorship with low revision and complication rates. Morbid obesity alone should not preclude consideration of fixed-bearing medial UKA in appropriately selected patients. 

Title
The Grip Gap: Ergonomic Mismatch in Orthopaedic Cement Gun Design 

Maria Choi, Stepping Hill Hospital, Stockport NHS Foundation Trust , John Ferns, Salford Royal Hospital, Northern Care Alliance NHS Trust, Simon Reuben, Stepping Hill Hospital, Stockport NHS Foundation Trust , North West Orthopaedic Research Collaborate (NWORC), David Flaherty, Tameside Hospital, Tameside and Glossop Integrated Care NHS Foundation Trust , Matthew Langstroth, Royal Blackburn Hospital, East Lancashire Hospitals NHS Trust, Raj Pradhan, Blackpool Victoria Hospital, Blackpool Teaching Hospitals NHS Foundation Trust, Gareth Rogers, Royal Bolton Hospital, Bolton NHS Foundation Trust, Sinead Cabezon, Royal Preston Hospital, Lancashire Teaching Hospitals NHS Foundation Trust 

Aims 
Despite a changing and increasingly diverse surgical workforce, many orthopaedic instruments remain unchanged in design. The orthopaedic cement gun is one such tool whose basic form has remained static for decades. This study aimed to compare commonly available cement gun designs, quantify the force required to deliver cement, and relate these demands to surgeons’ grip strength and hand dimensions. 

Methods 
Three commercially available cement guns were tested under controlled, reproducible conditions. A dynamometer measured the force required to fully depress the trigger of a loaded cement gun at defined time points during the working phase of cement. Orthopaedic registrars and consultants participated in hand metric measurement and maximal grip strength testing using a  dynamometer. 

Results 
There was a considerable difference in trigger force between cement guns, with a consistent force requirement difference of at least 57% between the best and worst-performing  guns.  Seventy-six surgeons participated in grip strength testing, with a mean maximal grip strength of 49 [27-82] kg-force. Female gender was associated with lower maximal grip strength (p<0.001). There was a significant positive correlation between maximal grip strength and metrics including glove size, hand length, hand width, middle finger length, and hand span.  

Conclusion 
Substantial variation exists between cement gun designs, which bears impact on their effective use. Female surgeons and those with smaller hands will be disproportionately affected. As the demographics of the orthopaedic workforce evolve, manufacturers should prioritise ergonomically adaptable designs to make instruments more inclusive to the modern surgeon cohort.  

Title
The Impact of Malrotating the Proximal Femoral Fragment During a Dynamic Hip Screw 

Introduction
Dynamic Hip Screw (DHS) fixation is one of the most common operations performed in orthopaedic trauma. However, rotational torque during screw insertion can result in clockwise rotation of the proximal femoral fragment, particularly in left sided fractures. This study aimed to quantify the effect of proximal fragment malrotation on the contact area between fracture fragments. 

Methods
Four femoral STL models were obtained from the National Institute of Health 3D print exchange. A total of 24 fractures (12 right-sided and 12 left-sided), classified as AO A1, were created using 3D modelling software. The proximal fragment was rotated clockwise about a defined axis corresponding to a 135° DHS trajectory. Tolerance-based contact area (≤ 1mm) was quantified at 1° increments using closest-point-to-triangle distances. 

Results
Tolerance-based contact area decreased nonlinearly with rotation. Contact was largely preserved with the first few degrees of rotation; however, beyond 3° of malrotation a rapid decline in contact area was observed. At 10° of rotation, contact area decreased by 36% [95% CI 21,43] in both left- and right-sided fractures. Proximal fractures demonstrated greater sensitivity to rotation, when compared to distal fractures.   

Conclusions
Rotation of the proximal fragment results in a nonlinear reduction in contact area. Rapid deterioration in contact area occurs after 3° of malrotation. This highlights the need for careful screening of the proximal fragment during screw placement and consideration of a de-rotational screw or wire. 

Referral Pathway Determines Diagnostic Delay in Bone and Soft Tissue Sarcoma: A Retrospective Cohort Study

Abstract Background
Bone and soft tissue sarcomas are rare malignancies in which delayed diagnosis is associated with poorer outcomes. Despite NICE guidance recommending urgent referral for suspected sarcoma, diagnostic delays remain common. This study evaluated the effect of referral pathway on time to specialist assessment and definitive treatment at a Scottish tertiary sarcoma centre.

Methods
A retrospective cohort study was conducted at Aberdeen Royal Infirmary between 2015 and 2022. Patients with histologically confirmed bone or soft tissue sarcoma were included. Patients with incomplete records or palliative management were excluded. Referral pathways were classified into four groups: urgent GP referral directly to the tertiary centre, non-urgent GP referral directly to the tertiary centre, urgent referral to another secondary care centre prior to onward referral, and referral to alternative specialties before sarcoma referral. Primary outcomes were time from first GP presentation to specialist clinic review and definitive treatment. Time intervals were analysed using descriptive statistics and Kruskal–Wallis testing.

Results
Fifty-eight patients were included. Median time to specialist clinic review was shortest in patients referred urgently directly to Aberdeen Royal Infirmary (23 days, IQR 19.5) and longest in those referred initially to other specialties (188 days, IQR 198). Median time to definitive treatment was 66 days (IQR 101) for urgent direct referrals, 120 days (IQR 116) for urgent referrals via other secondary care centres, 124.5 days (IQR 114) for non-urgent referrals and 279.5 days (IQR 166) for referrals through alternative specialties. Significant differences were observed between referral pathways for both time to specialist review (p=0.0019) and total time to treatment (p=0.0026).

Conclusion
Referral pathway significantly influences diagnostic delay in sarcoma. Urgent referral to specialist services was associated with earlier assessment and shorter time to treatment.

Title
Combined Fragility Fractures of the Femur and  Humerus in the Elderly confers increased risk of early  inpatient and 30-day mortality

Abstract
Background: To evaluate mortality outcomes and hospital length of stay in elderly patients  with combined fragility fractures of the femur and humerus (Combined Fracture group)  compared to isolated femoral fractures (Isolated Fracture group).

Methods
A retrospective case-control study was performed using data from two trauma units between January 2018 and 2024. Patients aged ≥60 years with concurrent femur and  humerus fractures were identified and matched to controls with isolated femur fractures by age, sex, ASA score, pre-admission residence, and mobility. Outcomes included inpatient, 30-day and 1-year mortality rates and duration of hospital admission 

Results
Fifty-six patients with combined fractures of humerus and femur were matched to 224 controls with isolated femur fractures. The Combined Fracture group had higher inpatient mortality (17.9 % vs. 7.1%, p=0.02) and 30-day mortality (14.3 % vs. 5.4 %, p=0.037). Mortality at 1 year was higher in the combined group (35.7% vs. 26.3%) but not statistically significant (p=0.184). There was no significant difference in length of hospital stay.

Conclusion
Combined fragility fractures of the femur and humerus are associated with increased short-term mortality compared to isolated femoral fractures. These findings highlight the importance of early identification, tailored multidisciplinary management, and consideration of surgical treatment of humeral fractures to optimise outcomes.

Keywords
Fragility fractures, mortality outcomes, and length of stay

Statements and Declarations
The authors have no competing interests to declare that are relevant to the content of this article.