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Orthopaedic Proceedings
Vol. 101-B, Issue SUPP_6 | Pages 37 - 37
1 May 2019
Windell L Haque A Kulkarni A Alabort E Barba D Reed R Singh H
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Background. Periprosthetic femoral fractures following total hip arthroplasty are relatively uncommon but are associated with significant morbidity. With an increasing number of total hip arthroplasties being carried out in an aging population we need to ensure correct implants are chosen for our patients. A recent review of NJR data suggested a significantly higher revision risk for the Zimmer CPT stems due to periprosthetic fractures when compared to the Stryker Exeter stems. Objectives. Our aim was to compare the biomechanics of periprosthetic fractures around the CPT and Exeter V40 stems in a composite saw bone model to identify if a difference in fracture risk exists between the two stems. We also compared the engineering design of the two implants in order to analyse the possible effect this may have on fracture risk. Study Design & Methods. Fourteen composite femurs were divided into two groups and cemented using Palacos R cement with either the CPT or Exeter V40 stem by a single surgeon. The implanted femurs were then mounted onto an Instron machine and were axially loaded and torqued to fracture with an axial compressive force of 2000N over 10 seconds followed by a rotation of 40 degrees applied over 1 second. A power calculation from a previous composite saw bone model study suggested that a minimum of 6 implanted femurs would be required in each group. Results. The implanted femurs invariably sustained fracture patterns similar to the Vancouver B2 periprosthetic fracture which are commonly seen in clinical practice. Implanted femurs with CPT stems suffered periprosthetic fractures with less rotation when compared to those femurs with the Exeter V40 stem (20.10 versus 33.60, p<0.01). We also found that CPT implanted femurs were fracturing at significantly lower torque values when compared to the Exeter V40 implanted femurs (124Nm Versus 174Nm, p<0.01). The energy release rate (G111) for CPT stems was 21.8Nm compared to 61.2Nm for Exeter V40 stems. The higher energy release with Exeter stems led to more comminuted fractures in Exeter implanted femurs when compared to the CPT femurs, which fractured earlier, but with simpler fracture patterns. Finite element method (FEM) simulation analysis showed that fractures initiated between the prosthesis and cement at the proximal end of the femur. Two dimensional sections at the same height showed a difference in bone-cement-implant geometrics at the critical point of failure suggesting that a design cause may be the reason for the higher risk of periprosthetic fractures in CPT implanted femurs. Conclusions. Our observations may explain the higher revision risk secondary to periprosthetic fractures that has been observed with the CPT stem when compared to the Exeter V40 stem


Bone & Joint Research
Vol. 9, Issue 7 | Pages 386 - 393
1 Jul 2020
Doyle R van Arkel RJ Muirhead-Allwood S Jeffers JRT

Aims

Cementless acetabular components rely on press-fit fixation for initial stability. In certain cases, initial stability is more difficult to obtain (such as during revision). No current study evaluates how a surgeon’s impaction technique (mallet mass, mallet velocity, and number of strikes) may affect component fixation. This study seeks to answer the following research questions: 1) how does impaction technique affect a) bone strain generation and deterioration (and hence implant stability) and b) seating in different density bones?; and 2) can an impaction technique be recommended to minimize risk of implant loosening while ensuring seating of the acetabular component?

Methods

A custom drop tower was used to simulate surgical strikes seating acetabular components into synthetic bone. Strike velocity and drop mass were varied. Synthetic bone strain was measured using strain gauges and stability was assessed via push-out tests. Polar gap was measured using optical trackers.


Orthopaedic Proceedings
Vol. 106-B, Issue SUPP_16 | Pages 70 - 70
19 Aug 2024
Heimann AF Kowal JH Lane PM Amundson AJ Tannast M Murphy SB
Full Access

Mixed Reality has the potential to improve accuracy and reduce required dissection for the performance of peri-acetabular osteotomy. The current work assesses initial proof of concept of MR guidance for PAO. A PAO planning module, based on preoperative computed tomography (CT) imaging, allows for the planning of PAO cut planes and repositioning of the acetabular fragment. 3D files (holograms) of the cut planes and native and planned acetabulum positions are exported with the associated spatial information. The files are then displayed on mixed reality head mounted device (HoloLens2, Microsoft) following intraoperative registration using an FDA-cleared mixed reality application designed primary for hip arthroplasty (HipInsight). PAO was performed on both sides of a bone model (Pacific Research). The osteotomies and acetabular reposition were performed in accordance with the displayed holograms. Post-op CT imaging was performed for analysis. Cutting plane-accuracy was evaluated using a best-fit plane and 2D angles (°) between the planned and achieved supra (SA)- and retroacetabular (RA) osteotomy and retroacetabular and ischial osteotomies (IO) were measured. To evaluate the accuracy of acetabular reorientation, we digitized the acetabular rim and calculated the acetabular opening plane. Absolute errors of planned and achieved operative inclination and anteversion (°) of the acetabular fragment, as well as 3D lateral-center-edge (LCE) angles were calculated. The mean absolute difference between the planned and performed osteotomy angles was 3 ± 3°. The mean absolute error between planned and achieved operative anteversion and inclination was 1 ± 0° and 0 ± 0° respectively. Mean absolute error between planned and achieved 3D LCE angle was 0.5 ± 0.7°. Mixed-reality guidance for the performance of pelvic osteotomies and acetabular fragment reorientation was feasible and highly accurate. This solution may improve the current standard of care by enabling reliable and precise reproduction of the desired acetabular realignment


Orthopaedic Proceedings
Vol. 106-B, Issue SUPP_16 | Pages 53 - 53
19 Aug 2024
Hellemondt van GG Colo E Faraj SSA Hooff van M Spruit M
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The objective of this study was to assess the clinical and radiological results of patients who were revised using a new generation custom-made triflange acetabular component (CTAC) for component loosening and large acetabular defect (Paprosky 3A and 3B) after previous total hip arthroplasty (THA). New generation CTACs involve the use of patient-specific drill guides and incorporate three-dimensional printed bone models, enhancing precision during surgical implantation. Data were extracted from a single centre prospective database of patients with large acetabular defects who were treated with a new generation CTAC. Patients were included if they had a minimum follow-up of five years. The modified Oxford Hip Score (mOHS), EurQol EuroQoL five-dimension three-level (EQ-5D-3L) utility, and Numeric Rating Scale (NRS), including visual analogue score (VAS) for pain, were gathered at baseline, and at two- and five-year follow-up. Reasons for revision, and radiological and clinical complications were registered. Trends over time are described and tested for significance (p<0.05). A total of 49 (70%) of 70 patients with a mean age of 73.5 years (SD 7.7) had a complete follow-up of 5 years. A significant improvement was found in HOOS, mOHS, EQ-5D-3L utility and NRS, VAS pain rest and activity between baseline and final follow-up. Complications included 8 cases with loosening screws, 4 with bony fractures, 4 periprosthetic infections and 2 cases with dislocation. One patient with bilateral pelvic discontinuity had revision surgery due to recurrent dislocations. No revision surgery was performed for screw failure or implant breakage. New generation CTAC in patients with THA acetabular loosening and massive acetabular bone loss (Paprosky 3A and 3B) can result in stable constructs and significant improvement in functioning and health-related quality of life at five years’ follow-up


Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_11 | Pages 25 - 25
1 Jun 2016
Ferguson D Henckel J Holme T Berber R Matthews W Carrington R Miles J Mitchell P Jagiello J Skinner J Hart A
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Introduction. Surgical simulation and ‘virtual’ surgical tools are becoming recognised as essential aids for speciality training in Trauma & Orthopaedics, as evidenced by the BOA T&O Simulation Curriculum 2013. 1,2. The current generation of hip arthroplasty simulators, including cadaveric workshops, offers the trainee limited exposure to reproducible real life bony pathology. We developed and implemented a novel training course using pathological dry bone models generated from real patient cases to support senior orthopaedic trainees and new consultants in developing knowledge and hands on skills in complex total hip arthroplasty. Patient/Materials & Methods. A two-day programme for 20 delegates was held at a specialist centre for hip arthroplasty. Three complex femoral and three complex acetabular cases were identified from patients seen at our centre. 3D models were printed from CT scans and dry bone models produced (using a mold-casting process), enabling each delegate to have a copy of each case at a cost of around £30 per case per delegate (Figure 1). The faculty was led by 4 senior Consultant revision hip surgeons. A computerised digitising arm was used to measure cup positioning and femoral stem version giving candidates immediate objective feedback (Figure 2). Candidate experience and satisfaction with the course and models was evaluated with a standardised post-course questionnaire. Results. 91% of respondents rated overall course satisfaction good or very good with 100% stating learning objectives were met or exceeded. 100% of delegates rated the bone model workshop cases as good or very good for the acetabular course, and 88% for the femoral course. Discussion. This course has been shown to enhance learning of surgical techniques and skills in complex hip surgery. Conclusion. We have developed a novel, effective and low cost training simulation method using pathological dry bone models for complex and revision hip arthroplasty which could be developed for other anatomical areas


The Bone & Joint Journal
Vol. 100-B, Issue 10 | Pages 1303 - 1309
1 Oct 2018
Nodzo SR Chang C Carroll KM Barlow BT Banks SA Padgett DE Mayman DJ Jerabek SA

Aims. The aim of this study was to evaluate the accuracy of implant placement when using robotic assistance during total hip arthroplasty (THA). Patients and Methods. A total of 20 patients underwent a planned THA using preoperative CT scans and robotic-assisted software. There were nine men and 11 women (n = 20 hips) with a mean age of 60.8 years (. sd. 6.0). Pelvic and femoral bone models were constructed by segmenting both preoperative and postoperative CT scan images. The preoperative anatomical landmarks using the robotic-assisted system were matched to the postoperative 3D reconstructions of the pelvis. Acetabular and femoral component positions as measured intraoperatively and postoperatively were evaluated and compared. Results. The system reported accurate values for reconstruction of the hip when compared to those measured postoperatively using CT. The mean deviation from the executed overall hip length and offset were 1.6 mm (. sd. 2.9) and 0.5 mm (. sd. 3.0), respectively. Mean combined anteversion was similar and correlated between intraoperative measurements and postoperative CT measurements (32.5°, . sd. 5.9° versus 32.2°, . sd. 6.4°; respectively; R. 2. = 0.65; p < 0.001). There was a significant correlation between mean intraoperative (40.4°, . sd. 2.1°) acetabular component inclination and mean measured postoperative inclination (40.12°, . sd. 3.0°, R. 2. = 0.62; p < 0.001). There was a significant correlation between mean intraoperative version (23.2°, . sd. 2.3°), and postoperatively measured version (23.0°, . sd. 2.4°; R. 2. = 0.76; p < 0.001). Preoperative and postoperative femoral component anteversion were significantly correlated with one another (R. 2. = 0.64; p < 0.001). Three patients had CT scan measurements that differed substantially from the intraoperative robotic measurements when evaluating stem anteversion. Conclusion. This is the first study to evaluate the success of hip reconstruction overall using robotic-assisted THA. The overall hip reconstruction obtained in the operating theatre using robotic assistance accurately correlated with the postoperative component position assessed independently using CT based 3D modelling. Clinical correlation during surgery should continue to be practiced and compared with observed intraoperative robotic values. Cite this article: Bone Joint J 2018;100-B:1303–9


Bone & Joint Open
Vol. 5, Issue 10 | Pages 858 - 867
11 Oct 2024
Yamate S Hamai S Konishi T Nakao Y Kawahara S Hara D Motomura G Nakashima Y

Aims

The aim of this study was to evaluate the suitability of the tapered cone stem in total hip arthroplasty (THA) in patients with excessive femoral anteversion and after femoral osteotomy.

Methods

We included patients who underwent THA using Wagner Cone due to proximal femur anatomical abnormalities between August 2014 and January 2019 at a single institution. We investigated implant survival time using the endpoint of dislocation and revision, and compared the prevalence of prosthetic impingements between the Wagner Cone, a tapered cone stem, and the Taperloc, a tapered wedge stem, through simulation. We also collected Oxford Hip Score (OHS), visual analogue scale (VAS) satisfaction, and VAS pain by postal survey in August 2023 and explored variables associated with those scores.


Bone & Joint Open
Vol. 5, Issue 4 | Pages 260 - 268
1 Apr 2024
Broekhuis D Meurs WMH Kaptein BL Karunaratne S Carey Smith RL Sommerville S Boyle R Nelissen RGHH

Aims

Custom triflange acetabular components (CTACs) play an important role in reconstructive orthopaedic surgery, particularly in revision total hip arthroplasty (rTHA) and pelvic tumour resection procedures. Accurate CTAC positioning is essential to successful surgical outcomes. While prior studies have explored CTAC positioning in rTHA, research focusing on tumour cases and implant flange positioning precision remains limited. Additionally, the impact of intraoperative navigation on positioning accuracy warrants further investigation. This study assesses CTAC positioning accuracy in tumour resection and rTHA cases, focusing on the differences between preoperative planning and postoperative implant positions.

Methods

A multicentre observational cohort study in Australia between February 2017 and March 2021 included consecutive patients undergoing acetabular reconstruction with CTACs in rTHA (Paprosky 3A/3B defects) or tumour resection (including Enneking P2 peri-acetabular area). Of 103 eligible patients (104 hips), 34 patients (35 hips) were analyzed.


Bone & Joint Research
Vol. 13, Issue 6 | Pages 272 - 278
5 Jun 2024
Niki Y Huber G Behzadi K Morlock MM

Aims

Periprosthetic fracture and implant loosening are two of the major reasons for revision surgery of cementless implants. Optimal implant fixation with minimal bone damage is challenging in this procedure. This pilot study investigates whether vibratory implant insertion is gentler compared to consecutive single blows for acetabular component implantation in a surrogate polyurethane (PU) model.

Methods

Acetabular components (cups) were implanted into 1 mm nominal under-sized cavities in PU foams (15 and 30 per cubic foot (PCF)) using a vibratory implant insertion device and an automated impaction device for single blows. The impaction force, remaining polar gap, and lever-out moment were measured and compared between the impaction methods.


Bone & Joint Research
Vol. 13, Issue 4 | Pages 193 - 200
23 Apr 2024
Reynolds A Doyle R Boughton O Cobb J Muirhead-Allwood S Jeffers J

Aims

Manual impaction, with a mallet and introducer, remains the standard method of installing cementless acetabular cups during total hip arthroplasty (THA). This study aims to quantify the accuracy and precision of manual impaction strikes during the seating of an acetabular component. This understanding aims to help improve impaction surgical techniques and inform the development of future technologies.

Methods

Posterior approach THAs were carried out on three cadavers by an expert orthopaedic surgeon. An instrumented mallet and introducer were used to insert cementless acetabular cups. The motion of the mallet, relative to the introducer, was analyzed for a total of 110 strikes split into low-, medium-, and high-effort strikes. Three parameters were extracted from these data: strike vector, strike offset, and mallet face alignment.


The Bone & Joint Journal
Vol. 105-B, Issue 3 | Pages 261 - 268
1 Mar 2023
Ruhr M Huber G Niki Y Lohner L Ondruschka B Morlock MM

Aims

The aim of the study was to investigate whether the primary stability of press-fit acetabular components can be improved by altering the impaction procedure.

Methods

Three impaction procedures were used to implant acetabular components into human cadaveric acetabula using a powered impaction device. An impaction frequency of 1 Hz until complete component seating served as reference. Overimpaction was simulated by adding ten strokes after complete component seating. High-frequency implantation was performed at 6 Hz. The lever-out moment of the acetabular components was used as measure for primary stability. Permanent bone deformation was assessed by comparison of double micro-CT (µCT) measurements before and after impaction. Acetabular component deformation and impaction forces were recorded, and the extent of bone-implant contact was determined from 3D laser scans.


Bone & Joint Open
Vol. 4, Issue 5 | Pages 306 - 314
3 May 2023
Rilby K Mohaddes M Kärrholm J

Aims

Although the Fitmore Hip Stem has been on the market for almost 15 years, it is still not well documented in randomized controlled trials. This study compares the Fitmore stem with the CementLeSs (CLS) in several different clinical and radiological aspects. The hypothesis is that there will be no difference in outcome between stems.

Methods

In total, 44 patients with bilateral hip osteoarthritis were recruited from the outpatient clinic at a single tertiary orthopaedic centre. The patients were operated with bilateral one-stage total hip arthroplasty. The most painful hip was randomized to either Fitmore or CLS femoral component; the second hip was operated with the femoral component not used on the first side. Patients were evaluated at three and six months and at one, two, and five years postoperatively with patient-reported outcome measures, radiostereometric analysis, dual-energy X-ray absorptiometry, and conventional radiography. A total of 39 patients attended the follow-up visit at two years (primary outcome) and 35 patients at five years. The primary outcome was which hip the patient considered to have the best function at two years.


Bone & Joint Open
Vol. 3, Issue 11 | Pages 867 - 876
10 Nov 2022
Winther SS Petersen M Yilmaz M Kaltoft NS Stürup J Winther NS

Aims

Pelvic discontinuity is a rare but increasingly common complication of total hip arthroplasty (THA). This single-centre study evaluated the performance of custom-made triflange acetabular components in acetabular reconstruction with pelvic discontinuity by determining: 1) revision and overall implant survival rates; 2) discontinuity healing rate; and 3) Harris Hip Score (HHS).

Methods

Retrospectively collected data of 38 patients (39 hips) with pelvic discontinuity treated with revision THA using a custom-made triflange acetabular component were analyzed. Minimum follow-up was two years (mean 5.1 years (2 to 11)).


Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_11 | Pages 13 - 13
1 Jun 2016
Aqil A Patel S Jones G Lewis A Cobb J
Full Access

Introduction. Outcomes following large joint arthroplasty are influenced by the accuracy of implant placement. Patient specific (PS) technology has been used in knee arthroplasty surgery however, its application in total hip arthroplasty remains relatively unexplored. Aims. We investigated whether conventional or PS guides, resulted in a more accurate reconstruction of the pre-operative head centre position. Methods. A pilot study, determined a minimum of 7 samples were required per group to ensure an adequately powered study. However in order to account for potential errors, ten specimens were prepared for both groups by a single surgeon and using a standardised operative technique. Both groups used instruments, available on standard operating sets, however PS guides were only used and available for the PS group. Following surgery, specimens were laser scanned to generate 3- dimensional surface models. These were then compared to models of a pre-operative specimen. The distance between the pre and post- operative femoral head centres (head position error) was then calculated. Results. This study analysed 19 implanted specimens, as one specimen was excluded due to an error in preparation. The median and range head position error was 8mm (3.5–10.3) in the conventional group and 3.9mm (2.2–7.4) in the PS group. This difference was statistically significant (U=8.5, z=−2.983, p=0.003). Discussion. We found that the use of PS guides halved the average head position error and reduced the range of errors. A difference of 4.1mm in head centre position was both statistically and clinically significant. Conclusions. PS technology improves the accuracy of hip arthroplasty surgery in a dry bone model. It would be reasonable for future studies to further assess the use of PS guides in vivo as part of a clinical trial


Bone & Joint Research
Vol. 11, Issue 5 | Pages 270 - 277
6 May 2022
Takegami Y Seki T Osawa Y Imagama S

Aims

Periprosthetic hip fractures (PPFs) after total hip arthroplasty are difficult to treat. Therefore, it is important to identify modifiable risk factors such as stem selection to reduce the occurrence of PPFs. This study aimed to clarify differences in fracture torque, surface strain, and fracture type analysis between three different types of cemented stems.

Methods

We conducted biomechanical testing of bone analogues using six cemented stems of three different types: collarless polished tapered (CPT) stem, Versys Advocate (Versys) stem, and Charnley-Marcel-Kerboull (CMK) stem. Experienced surgeons implanted each of these types of stems into six bone analogues, and the analogues were compressed and internally rotated until failure. Torque to fracture and fracture type were recorded. We also measured surface strain distribution using triaxial rosettes.


Bone & Joint Research
Vol. 10, Issue 10 | Pages 629 - 638
20 Oct 2021
Hayashi S Hashimoto S Kuroda Y Nakano N Matsumoto T Ishida K Shibanuma N Kuroda R

Aims

This study aimed to evaluate the accuracy of implant placement with robotic-arm assisted total hip arthroplasty (THA) in patients with developmental dysplasia of the hip (DDH).

Methods

The study analyzed a consecutive series of 69 patients who underwent robotic-arm assisted THA between September 2018 and December 2019. Of these, 30 patients had DDH and were classified according to the Crowe type. Acetabular component alignment and 3D positions were measured using pre- and postoperative CT data. The absolute differences of cup alignment and 3D position were compared between DDH and non-DDH patients. Moreover, these differences were analyzed in relation to the severity of DDH. The discrepancy of leg length and combined offset compared with contralateral hip were measured.


The Bone & Joint Journal
Vol. 103-B, Issue 9 | Pages 1497 - 1504
1 Sep 2021
Rotman D Ariel G Rojas Lievano J Schermann H Trabelsi N Salai M Yosibash Z Sternheim A

Aims

Type 2 diabetes mellitus (T2DM) impairs bone strength and is a significant risk factor for hip fracture, yet currently there is no reliable tool to assess this risk. Most risk stratification methods rely on bone mineral density, which is not impaired by diabetes, rendering current tests ineffective. CT-based finite element analysis (CTFEA) calculates the mechanical response of bone to load and uses the yield strain, which is reduced in T2DM patients, to measure bone strength. The purpose of this feasibility study was to examine whether CTFEA could be used to assess the hip fracture risk for T2DM patients.

Methods

A retrospective cohort study was undertaken using autonomous CTFEA performed on existing abdominal or pelvic CT data comparing two groups of T2DM patients: a study group of 27 patients who had sustained a hip fracture within the year following the CT scan and a control group of 24 patients who did not have a hip fracture within one year. The main outcome of the CTFEA is a novel measure of hip bone strength termed the Hip Strength Score (HSS).


Bone & Joint Open
Vol. 1, Issue 9 | Pages 512 - 519
1 Sep 2020
Monzem S Ballester RY Javaheri B Poulet B Sônego DA Pitsillides AA Souza RL

Aims

The processes linking long-term bisphosphonate treatment to atypical fracture remain elusive. To establish a means of exploring this link, we have examined how long-term bisphosphonate treatment with prior ovariectomy modifies femur fracture behaviour and tibia mass and shape in murine bones.

Methods

Three groups (seven per group) of 12-week-old mice were: 1) ovariectomized and 20 weeks thereafter treated weekly for 24 weeks with 100 μm/kg subcutaneous ibandronate (OVX+IBN); 2) ovariectomized (OVX); or 3) sham-operated (SHAM). Quantitative fracture analysis generated biomechanical properties for the femoral neck. Tibiae were microCT scanned and trabecular (proximal metaphysis) and cortical parameters along almost its whole length measured.


Bone & Joint Research
Vol. 9, Issue 9 | Pages 534 - 542
1 Sep 2020
Varga P Inzana JA Fletcher JWA Hofmann-Fliri L Runer A Südkamp NP Windolf M

Aims

Fixation of osteoporotic proximal humerus fractures remains challenging even with state-of-the-art locking plates. Despite the demonstrated biomechanical benefit of screw tip augmentation with bone cement, the clinical findings have remained unclear, potentially as the optimal augmentation combinations are unknown. The aim of this study was to systematically evaluate the biomechanical benefits of the augmentation options in a humeral locking plate using finite element analysis (FEA).

Methods

A total of 64 cement augmentation configurations were analyzed using six screws of a locking plate to virtually fix unstable three-part fractures in 24 low-density proximal humerus models under three physiological loading cases (4,608 simulations). The biomechanical benefit of augmentation was evaluated through an established FEA methodology using the average peri-screw bone strain as a validated predictor of cyclic cut-out failure.


The Bone & Joint Journal
Vol. 101-B, Issue 12 | Pages 1585 - 1592
1 Dec 2019
Logishetty K Rudran B Cobb JP

Aims

Arthroplasty skills need to be acquired safely during training, yet operative experience is increasingly hard to acquire by trainees. Virtual reality (VR) training using headsets and motion-tracked controllers can simulate complex open procedures in a fully immersive operating theatre. The present study aimed to determine if trainees trained using VR perform better than those using conventional preparation for performing total hip arthroplasty (THA).

Patients and Methods

A total of 24 surgical trainees (seven female, 17 male; mean age 29 years (28 to 31)) volunteered to participate in this observer-blinded 1:1 randomized controlled trial. They had no prior experience of anterior approach THA. Of these 24 trainees, 12 completed a six-week VR training programme in a simulation laboratory, while the other 12 received only conventional preparatory materials for learning THA. All trainees then performed a cadaveric THA, assessed independently by two hip surgeons. The primary outcome was technical and non-technical surgical performance measured by a THA-specific procedure-based assessment (PBA). Secondary outcomes were step completion measured by a task-specific checklist, error in acetabular component orientation, and procedure duration.