Introduction

The current methods for measuring femoral torsion have limitations, including variability and inaccuracies. Existing 3D methods are not reliable for abnormal femoral anteversion measurement. A new 3D method is needed for accurate measurement and planning of proximal femoral osteotomies. Currently available software for viewing and modelling CT data lacks measurement capabilities. The MSK Hip planner aims to address these limitations by combining measurement, planning, and analysis functionalities into one tool. We aim to answer 5 key questions: Is there a difference between 2D measurement methods? Is there a difference between 3D measurement methods? Is there a difference between 2D and 3D measurement methods? Are any of the measurement methods affected by the presence of osteoarthritis or a CAM deformity?

Introduction

Bernese periacetabular osteotomy (PAO) repositions the acetabulum to increase femoral head coverage (FHC) in hip dysplasia. Currently, there is a paucity of objective peri-operative metrics to plan for optimal acetabular fragment repositioning. The MSk Lab Hip 3D Planner (MSkL-HP) measures acetabular morphology and simulates PAO cuts to achieve optimal FHC. We evaluated how adjusting location and orientation of cutting planes can alter FHC.

Anterior approach total hip arthroplasty (AA-THA) has a steep learning curve, with higher complication rates in initial cases. Proper surgical case selection during the learning curve can reduce early risk. This study aims to identify patient and radiographic factors associated with AA-THA difficulty using Machine Learning (ML).

Consecutive primary AA-THA patients from two centres, operated by two expert surgeons, were enrolled (excluding patients with prior hip surgery and first 100 cases per surgeon). K- means prototype clustering – an unsupervised ML algorithm – was used with two variables - operative duration and surgical complications within 6 weeks - to cluster operations into difficult or standard groups.

Radiographic measurements (neck shaft angle, offset, LCEA, inter-teardrop distance, Tonnis grade) were measured by two independent observers. These factors, alongside patient factors (BMI, age, sex, laterality) were employed in a multivariate logistic regression analysis and used for k-means clustering. Significant continuous variables were investigated for predictive accuracy using Receiver Operator Characteristics (ROC).

Out of 328 THAs analyzed, 130 (40%) were classified as difficult and 198 (60%) as standard. Difficult group had a mean operative time of 106mins (range 99–116) with 2 complications, while standard group had a mean operative time of 77mins (range 69–86) with 0 complications. Decreasing inter-teardrop distance (odds ratio [OR] 0.97, 95% confidence interval [CI] 0.95–0.99, p = 0.03) and right-sided operations (OR 1.73, 95% CI 1.10–2.72, p = 0.02) were associated with operative difficulty. However, ROC analysis showed poor predictive accuracy for these factors alone, with area under the curve of 0.56. Inter-observer reliability was reported as excellent (ICC >0.7).

Right-sided hips (for right-hand dominant surgeons) and decreasing inter-teardrop distance were associated with case difficulty in AA-THA. These data could guide case selection during the learning phase. A larger dataset with more complications may reveal further factors.

Current evidence suggests that superior surgical team performance is linked to fewer intra-operative errors, reductions in mortality and even improved patient outcomes. Virtual reality has demonstrated excellent efficacy in training surgeons and scrub nurses individually, however its impact on training teams is currently unknown. This study aimed to assess if training together (scrub nurse and surgeon) in an innovative multiplayer virtual reality program was superior to single player training for novices learning anterior approach total hip arthroplasty (AA-THA).

40 participants (20 novice surgeons (CT1-ST3 level) and 20 novice scrub nurses) were enrolled in this study and randomised to individual or team virtual reality training. Individually-trained participants played with virtual avatar counterparts, whilst teams trained live in pairs (surgeon and scrub nurse). Both groups underwent 5 VR training sessions over 6 weeks. Subsequently, they underwent a real-life assessment in which they performed AA-THA on a high-fidelity model with real equipment in a simulated operating theatre. Teams performed together and individually-trained participants were randomly paired up with a solo player of the opposite role. Videos of the assessment were marked by two blinded expert assessors. The primary outcome was team performance as graded by the validated NOTECHs II score. Secondary outcomes were procedure time and number of technical errors from an expert pre-defined protocol.

Teams outperformed individually-trained participants for non-technical skills in the real-world assessment (NOTECHS-II score 50.3 ± 6.04 vs 43.90 ± 5.90, p=0.0275). They completed the assessment 28.1% faster (31.22 minutes ±2.02 vs 43.43 ±2.71, p=0.01), and made close to half the number of technical errors when compared to the individual group (12.9 ± 8.3 vs 25.6 ± 6.1, p=0.001).

Multiplayer, team training appears to lead to faster surgery with fewer technical errors and the development of superior non-technical skills.

Evidence supporting the use of virtual reality (VR) training in orthopaedic procedures is rapidly growing. However, the impact of the timing of delivery of this training is yet to be tested. We aimed to investigate whether spaced VR training is more effective than massed VR training.

24 medical students with no hip arthroplasty experience were randomised to learning the direct anterior approach total hip arthroplasty using the same VR simulation, training either once-weekly or once-daily for four sessions. Participants underwent a baseline physical world assessment on a saw bone pelvis. The VR program recorded procedural errors, time, assistive prompts required and hand path length across four sessions. The VR and physical world assessments were repeated at one-week, one-month, and 3 months after the last training session.

Baseline characteristics between the groups were comparable (p > 0.05). The daily group demonstrated faster skills acquisition, reducing the median ± IQR number of procedural errors from 68 ± 67.05 (session one) to 7 ± 9.75 (session four), compared to the weekly group's improvement from 63 ± 27 (session one) to 13 ± 15.75 (session four), p < 0.001. The weekly group error count plateaued remaining at 14 ± 6.75 at one-week, 16.50 ± 16.25 at one-month and 26.45 ± 22 at 3-months, p < 0.05. However, the daily group showed poorer retention with error counts rising to 16 ± 12.25 at one-week, 17.50 ± 23 at one-month and 41.45 ± 26 at 3-months, p<0.01. A similar effect was noted for the number of assistive prompts required, procedural time and hand path length. In the real-world assessment, both groups significantly improved their acetabular component positioning accuracy, and these improvements were equally maintained (p<0.01).

Daily VR training facilitates faster skills acquisition; however weekly practice has superior skills retention.

Abstract

Abstract

Patients undergoing hip resurfacing arthroplasty (HRA) is typically reserved for highly active patients. Patient Reported Outcome Measures (PROMs) such as the Oxford Hip Score (OHS) are reported to have ceiling effects, which may limit physicians' ability to measure health gain in these patients. The Metabolic Equivalent of Task (MET) index is a validated compendium assigning energy expenditure to a wide range of activities; for example, a slow walk expends 2.9 kcal/kg/hour, golf expends 4.0 kcal/kg/hour, while moderate lacrosse typically expends 8.1 kcal/kg/hour. We hypothesized that for patients with high OHS (47–48) after HRA, the MET index could better discriminate between high-performing individuals.

We evaluated 97 consecutive HRA patients performed by a single surgeon. They prospectively completed an online Oxford Hip Score. They also listed three activities which they had performed independently in the preceding 2 weeks with a Likert-scale slider denoting intensity of effort. Matched data-sets were obtained from 51 patients, from which 23 had OHS of 47–48 at 6-months. Their activity with the highest MET index was selected for analysis. The 23 patients' OHS improved from 29.3 ± 7.0 preoperatively to 47.6 ± 0.5 after 6-months, while their MET indices improved from 8.5 ± 3.7 to 12.9 ± 3.5 kcal/kg/hr. The activities performed by these high-performance individuals ranged from the lowest, pilates (8.05 kcal/kg/hour), to highest, running at 22km/hr (23 kcal/kg/hour). 45% of patients undergoing HRA in this cohort had OHS of 47 and 48 at 6-months after surgery.

Unlike the OHS, the MET index described variation in physical activity in these high-performance individuals, and did so on an objective measurable scale.

The hip's capsular ligaments (CL) passively restrain extreme range of motion (ROM) by wrapping around the native femoral head/neck, and protect against impingement and instability. We compared how CL function was affected by device (hip resurfacing arthroplasty, HRA; dual mobility total hip arthroplasty, DM-THA; and conventional THA, C-THA), and surgical approach (anterior and posterior), with and without CL surgical-repair. We hypothesized that CL function would only be preserved when native head-size (HRA/DM-THA) was restored.

CL function was quantified on sixteen cadaveric hips, by measuring ROM by internally (IR) and externally rotating (ER) the hip in six functional positions, ranging from full extension with abduction to full flexion with adduction (squatting). Native ROM was compared to ROM after posterior capsulotomy (right hips) or anterior capsulotomy (left hips), and HRA, and C-THA and DM-THA, before and after CL repair.

Independent of approach, ROM increased most following C-THA (max 62°), then DM-THA (max 40°), then HRA (max 19°), indicating later CL engagement and reduced biomechanical function with smaller head-size. Dislocations also occurred in squatting after C-THA and DM-THA. CL-repair following HRA restored ROM to the native hip (max 8°). CL-repair following DM-THA reduced ROM hypermobility in flexed positions only and prevented dislocation (max 36°). CL-repair following C-THA did not reduce ROM or prevent dislocation.

For HRA and repair, native anatomy was preserved and ligament function was restored. For DM-THA with repair, ligament function depended on the movement of the mobile-bearing, with increased ROM in positions when ligaments could not wrap around head/neck. For C-THA, the reduced head-size resulted in inferior capsular mechanics in all positions as the ligaments remained slack, irrespective of repair.

Choosing devices with anatomic head-sizes (HRA/DM-THA) with capsular repair may have greater effect than surgical approach to protect against instability in the early postoperative period.

Background

Accurate implant orientation is associated with improved outcomes after artificial joint replacement. We investigated if a novel augmented-reality (AR) platform (with live feedback) could train novice surgeons to orientate an acetabular implant as effectively as conventional training (CT).

Background

Complications such as dislocations, impingement and early wear following total hip arthroplasty (THA) increase with acetabular cup implant malorientation. These errors are more common with low-volume centres or in novice hands. Currently, this skill is most commonly taught during real surgery with an expert trainer, but simulated training may offer a safer and more accessible solution. This study investigated if a novel MicronTracker® enhanced Microsoft HoloLens® augmented reality (EAR) headset was as effective as one-on-one expert surgeon (ES) training for teaching novice surgeons hip cup orientation skill.

Background

Trust in the validity of a measurement tool is critical to its function in both clinical and educational settings. Acetabular cup malposition within total hip arthroplasty (THA) can lead to increased dislocation rates, impingement and increased wear as a result of edge loading. We have developed a THA simulator incorporating a foam/Sawbone pelvis model with a modified Microsoft HoloLens® augmented reality (AR) headset. We aimed to measure the trueness, precision, reliability and reproducibility of this platform for translating spatial measurements of acetabular cup orientation to angular values before developing it as a training tool.