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.
Reports of improved functional outcome of Metal on Metal Hip Resurfacing Arthroplasty (mHRA) to Total Hip Replacement needs to be balanced with concerns of metal ion release. By removing cobalt-chrome, cHRA reduces these risks. To the author's knowledge, there is no data available on functional outcomes of cHRA, therefore the aim of the study was to compare the function between cHRA patients and mHRA patients. 24 patients received a unilateral cHRA (H1, Embody) and was compared to 24 age and gender matched patients with a unilateral mHRA (BHR, Smith and Nephew). All patients completed the Oxford Hip Score (OHS)[T2] and underwent gait analysis on an instrumented treadmill before and at a mean of 74wks (+/− 10) for mHRA and 53wks (+/− 2) for cHRA post op. Walking trials started at 4km/h and increased in 0.5km/h increments until a top walking speed (TWS) was achieved. Vertical ground reaction forces (GRF) were recorded along with the symmetry index (SI). Spatiotemporal measures of gait were also recorded. Vertical GRF were captured for the entire normalised stance phase using statistical parametric mapping (SPM; CI = 95%). The gain in OHS was similar: H1 (25-46), BHR(27-47). TWS increased by 19% with H1 (6.02 – 8.0km/hr), and 20% with BHR (6.02 – 7.37km/hr). SPM of the entire gait cycle illustrated the restoration of symmetry in both groups with no difference in GRF across the stance phase between groups at 5km/hr pre-op and post-op. At faster speeds (6.5km/hr), H1 patients had a mid-support GRF slightly closer to normal compared to BHR. Both groups increased step length similar from pre to post op (H1:0.76 – 0.85cm, BHR:0.77-0.86cm). In this study, subjective and objective functional outcome measures suggest that short term functional outcomes of ceramic resurfacing is not inferior to metal resurfacing.
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.
Non-technical skills including teamwork play a pivotal role in surgical outcomes. Virtual reality is effective at improving technical skills, however there is a paucity of evidence on team-based virtual reality (VR) training. This study aimed to assess if multiplayer virtual reality training was superior to solo training for acquisition of both technical and non-technical skills in learning the complex anterior approach total hip arthroplasty operation. 10 novice surgeons and 10 novice scrub nurses, were randomised to solo or team virtual reality training to perform anterior approach total hip arthroplasty. Solo participants trained with virtual avatar counterparts, whilst teams trained in pairs (surgeon and scrub nurse). Both groups underwent 5 VR training sessions over 6 weeks. Then, 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 solo participants were randomly paired up with a solo player of the opposite role. Videos of the assessment were marked by two blinded expert assessors. Outcomes were procedure time, procedural errors from an expert pre-defined protocol and acetabular component positioning. Non-technical skills were assessed using the NOTECHs II and NOTSS scores.Abstract
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Although hip replacement and resurfacing procedures both aim to restore mobility, improve joint function, and relieve pain, it is unclear how each differ in terms of gait mechanics and if they are affected by varying walking speeds. We compared limb symmetry and ground reaction force (GRF) profiles between bilateral total hip arthroplasty patients (THA), bilateral hip resurfacing arthroplasty patients (HRA), and healthy control participants (CON) during level-treadmill walking at different speeds. Bilateral THA and bilateral HRA patients (nTHA = 15; nHRA = 15; postoperative 12–18 months), and age-, mass-, and height-matched CON participants (nCON = 20) underwent gait analysis on an instrumented treadmill. Walking trials started at 4 km/h and increased in 0.5 km/h increments until top walking speed (TWS) was achieved. Gait symmetry index (SI = 0% for symmetry) was assessed between limbs during weight-acceptance, mid-stance and push-off phases of gait; and vertical GRFs were captured for the normalised stance phase using statistical parametric mapping (SPM; CI = 95%).Abstract
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Evidence supporting the use of immersive virtual reality (iVR) training in orthopaedic procedures is rapidly growing. However, the impact of the timing of delivery of this training is yet to be tested. This study investigated whether spaced iVR training is more effective than massed iVR training for novices learning hip arthroplasty. 24 medical students with no hip arthroplasty experience were randomised to learning total hip arthroplasty using the same iVR simulation training either once-weekly or once-daily for four sessions. Participants underwent a baseline physical world assessment to orientate an acetabular component on a saw bone pelvis, and a baseline knowledge test. In iVR, we recorded procedural errors, time, numbers of prompts required and path lengths of the hands and head across 4 sessions. To assess skill retention, the iVR and baseline physical world assessments were repeated at one-week and one-month.Abstract
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Unicompartmental and total knee arthroplasty (UKA and TKA) are successful treatments for osteoarthritis, but monolithic implants disrupt the natural homeostasis of bone which leads to bone loss over time. This can cause problems if the implant needs to be revised. This study aimed to demonstrate that tibial implants made from titanium lattice could replace the tibial condyle surface while minimising disruption of the bone's natural mechanical loading environment. A secondary aim was to determine whether implants perform better if they replicate more closely bone's mechanical modulus, anisotropy and spatial heterogeneity. This study was conducted in a human cadaveric model. In a cadaveric model, UKA and TKA procedures were performed on 8 fresh-frozen knee specimens by a board-certified consultant orthopaedic surgeon, using tibial implants made from conventional monolithic material and titanium lattice structures. Stress at the bone-implant interfaces was measured with pressure film and compared to the native knee.Abstract
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There is renewed interest in bi-unicondylar arthroplasty (Bi-UKA) for patients with medial and lateral tibiofemoral osteoarthritis, but a spared patellofemoral compartment and functional cruciate ligaments. The bone island between the two tibial components may be at risk of tibial eminence avulsion fracture, compromising function. This finite element analysis compared intraoperative tibial strains for Bi-UKA to isolated medial unicompartmental arthroplasty (UKA-M) to assess the risk of avulsion. A validated model of a large, high bone-quality tibia was prepared for both UKA-M and Bi-UKA. Load totalling 450N was distributed between the two ACL bundles, implant components and collateral ligaments based on experimental and intraoperative measurements with the knee extended and appropriately sized bearings used. 95th percentile maximum principal elastic strain was predicted in the proximal tibia. The effect of overcuts/positioning for the medial implant were studied; the magnitude of these variations was double the standard deviation associated with conventional technique.Abstract
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Although surgical periacetabular osteotomy (PAO) for hip dysplasia aims to optimise acetabular coverage and restore hip function, it is unclear how surgery affects capsular mechanics and joint stability. The purpose was to examine how the reoriented acetabular coverage affects capsular mechanics and joint stability in dysplastic hips. Twelve cadaveric dysplastic hips (n = 12) were denuded to the capsule and mounted onto a robotic tester. The robot positioned each hip in multiple flexion angles (Extension, Neutral 0°, Flexion 30°, Flexion 60°, Flexion 90°) and performed internal-external rotations and abduction-adduction to 5 Nm in each rotational or planar direction. Each hip underwent a PAO, preserving the capsule, and was retested postoperatively in the robot. Paired sample t-tests compared the range of motion before and after PAO surgery (CI = 95%).Abstract
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The need for gender specific knee arthroplasty is debated. This research aimed to establish whether gender differences in patellar tendon moment arm (PTMA), a composite measure that characterises function of both the patellofemoral and tibiofemoral joints, are a consequence of knee size or other variation. PTMA about the instantaneous helical axis was calculated from positional data acquired using optical tracking. First, data post-processing was optimised, comparing four smoothing techniques (raw, Butterworth filtered, generalised cross-validation cubic spline interpolated and combined filtered/interpolated) using a fabricated knee. Then PTMA was measured during open-chain extension for N=24 (11 female) fresh-frozen cadaveric knees, with physiologically based loading and extension rates (420°/s) applied. Gender differences in PTMA were assessed before and after accounting for knee size with epicondylar width.Abstract
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Cam femoroacetabular impingement (FAI – femoral head-neck deformity) and developmental dysplasia of the hip (DDH – insufficient acetabular coverage) constitute a large portion of adverse hip loading and early degeneration. Spinopelvic anatomy may play a role in hip stability thus we examined which anatomical relationships can best predict range of motion (ROM). Twenty-four cadaveric hips with cam FAI or DDH (12:12) were CT imaged and measured for multiple femoral (alpha angles, head-neck offset, neck angles, version), acetabular (centre-edge angle, inclination, version), and spinopelvic features (pelvic incidence). The hips were denuded to the capsule and mounted onto a robotic tester. The robot positioned each hip in multiple flexion angles (Extension, Neutral 0°, Flexion 30°, Flexion 60°, Flexion 90°); and performed internal-external rotations to 5 Nm in each position. Independent t-tests compared the anatomical parameters and ROM between FAI and DDH (CI = 95%). Multiple linear regressions determined which anatomical parameters could predict ROM.Abstract
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Unicompartmental (UKA) and bicompartmental (BCA) knee arthroplasty are associated with improved functional outcomes compared to Total Knee Arthroplasty (TKA) in suitable patients, although the reason is poorly understood. The aim of this study was to measure how the different arthroplasties affect knee extensor function. Extensor function was measured for sixteen cadaveric knees and then re-tested following the different arthroplasties. Eight knees underwent medial UKA then BCA, then posterior-cruciate retaining TKA, and eight underwent the lateral equivalents then TKA. Extensor efficiency was calculated for ranges of knee flexion associated with common activities of daily living. Data were analyzed with repeated measures analysis of variance (α=0.05).Abstract
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Patellofemoral osteoarthritis (PFOA) affects 32% men and 36% women over the age of 60years and is associated with anterior knee pain, stiffness, and poor mobility. Patellofemoral arthroplasty (PFA) is a bone-sparing treatment for isolated PFOA. This study set out to investigate the relationship between patient-related outcome measures (PROMs) and measurements obtained from gait analysis before and after PFA. There are currently no studies relating to gait analysis and PFA available in the literature A prospective cohort study was conducted of ten patients known to have isolated PFOA who had undergone PFA compared to a gender and age matched control group. The patients were also asked to complete questionnaires (Oxford knee score (OKS), EQ-5D-5L) before surgery and one year after surgery. Gait analysis was done on an instrumented treadmill comparing Ground reaction force parameters between the control and pre and post-operative PFA patients The average age 60 (49–69) years with a female to male ratio of 9:1. Patient and healthy subjects were matched for age and gender, with no significant difference in BMI. Post-op PFA improvement in gait seen in ground reaction force at 6.5km/h. Base support difference was statistically significant both on the flat P=0.0001 and uphill P=0.429 (5% inclination) and P=0.0062 (10% inclination). PROMS response rate was 70%(7/10) pre-operative and 60%(6/10) post-operative. EQ-5D-5L scores reflected patient health state was better post-operatively. This study found that gait analysis provides an objective measure of functional gait and reflected by significant quality-of-life improvement of patients post PFA. Literature lacks studies relating to gait-analysis and PFA. Valuable information provided by this study highlights that PFA has a beneficial outcome reflected by PROMs and improvement in vertical ground reaction force and gait Further research is needed to assess how care-providers may use gait-analysis as part of patient care plans for PFOA patients.
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.
With information about a patient's bone mechanical properties orthopaedic operations could be optimised to reduce intra- and post-operative complications. However, there is currently no reliable method of measuring a patient's bone mechanical properties in vivo. We have previously investigated microindentation, using a 1.5mm diameter spherical indenter tip, and found no correlation between these measurements and compression testing measurements. We hypothesised that by using a larger diameter indenter tip we would closer match bone millimetre-scale mechanical properties. 20 bone samples were taken from 20 patients undergoing hip replacement surgery. The samples were machined from the femoral neck calcar cortical bone into 6×3×3mm parallelepiped specimens, aligned with the osteons along the long axis. The samples were micro-computed tomography (CT) scanned to calculate porosity. Microindentation was performed using a 6mm diameter, sapphire, spherical indenter tip. 12 indentations were performed in a grid and the reduced moduli were calculated using the Oliver-Pharr method. Compression testing was then performed to failure and the apparent elastic modulus was calculated for each sample. A moderate correlation was found between the indentation reduced moduli and compression testing elastic moduli (r=0.52, r2=0.275, p=0.018). In addition, a moderate correlation was found between the indentation reduced moduli and CT-measured porosity (r=0.5, r2=0.251, p=0.025) and a strong correlation was found between compression testing moduli and porosity (r=0.75, r2=0.568, p<0.001). Using large-tip spherical microindentation, indentation reduced moduli correlated significantly with compression testing apparent elastic moduli in these 20 cortical bone specimens. Microindentation using a large, spherical indenter tip may predict the mechanical properties of bone at the millimetre length scale and shows promise as a potential future clinical decision aid in surgery.
Tibial bone density may affect implant stability and functional outcomes following total knee replacement (TKR). Our aim was to characterise the bone density profile at the implant-tibia interface following TKR in mechanical versus kinematic alignment. Pre-operative computed tomography scans for 10 patients were obtained. Using surgical planning software, tibial cuts were made for TKR either neutral (mechanical) or 3 degrees varus (kinematic) alignment. Signal intensity, in Hounsfield Units (HU), was measured at 25,600 points throughout an axial slice at the implant-tibia interface and density profiles compared along defined radial axes from the centre of the tibia towards the cortices. From the tibial centre towards the lateral cortex, trabecular bone density for kinematic and mechanical TKR are similar in the inner 50% but differ significantly beyond this (p= 0.012). There were two distinct density peaks, with peak trabecular bone density being higher in kinematic TKR (p<0.001) and peak cortical bone density being higher in mechanical TKR (p<0.01). The difference in peak cortical to peak trabecular signal was 43 HU and 185 HU respectively (p<0.001). On the medial side there was no significant difference in density profile and a linear increase from centre to cortex. In the lateral proximal tibia, peak cortical and peak trabecular bone densities differ between kinematic TKR and mechanical TKR. Laterally, mechanical TKR may be more dependent upon cortical bone for support compared to kinematic TKR, where trabecular bone density is higher. This may have implications for surgical planning and implant design.
Hip resurfacing arthroplasty (HRA) and total hip arthroplasty (THA) are treatments of end-stage hip disease. Gait analysis studies comparing HRA and THA have demonstrated HRA results in a more normal gait than THA. The reasons may include the larger, more anatomic head diameter, the preservation of the femoral neck with restoration of the anatomical hip centre position and normal proprioception. This study investigated (1)whether femoral head size diameter affects gait; (2)whether gait still differs between THA and HRA patients even with comparable head diameters. We analysed the gait of 33 controls and 50 patients with unilateral hip replacement. Follow-up ranged from 9–68 months. In 27 hips a small femoral head size was used (≤ 36mm); in 23 hips a large head size (>36mm). The small size group consisted of 11 long femoral stem THA and 16 short-stem THA; the large group of 5 long-stem, 8 short-stem THA and 10 HRA patients. There were 14 females/19 males in the control group; 22 females/5 males in the small size group; 13 females/10 males in the large size group.Background
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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). Twenty-four novice surgeons (pre-registration level medical students) voluntarily participated in this trial. Baseline demographics, data on exposure to hip arthroplasty, and baseline performance in orientating an acetabular implant to six patient-specific values on a phantom pelvis, were collected prior to training. Participants were randomised to a training session either using a novel AR headset platform or receiving one-on-one tuition from a hip surgeon (CT). After training, they were asked to perform the six orientation tasks again. The solid-angle error in degrees between the planned and achieved orientations was measured using a head-mounted navigation system.Background
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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. Twenty-four medical students were randomly assigned to EAR or ES training groups. Participants used a modified sawbone/foam pelvis model for hip cup orientation simulation. A validated EAR headset measured the orientation of acetabular cup implants and displayed this in the participant”s field of view. The system calculated the difference between planned and achieved orientation as a solid-angle error. Six different inclination and anteversion combinations, related to hypothetical patient-specific anatomy, were used as target orientations. Learning curves were measured over four sessions, each one week apart. Error in orientations of non-taught angles and during a concealed pelvic tilt were measured to assess translation of skills. A post-test questionnaire was used for qualitative analysis of procedure understanding and participant experience.Background
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