Augmented reality simulators offer opportunities for practice of orthopaedic procedures outside of theatre environments. We developed an augmented reality simulator that allows trainees to practice pinning of paediatric supracondylar humeral fractures (SCHF) in a radiation-free environment at no extra risk to patients. The simulator is composed of a tangible child's elbow model, and simulated fluoroscopy on a tablet device. The treatment of these fractures is likely one of the first procedures involving X-ray guided wire insertion that trainee orthopaedic surgeons will encounter. This study aims to examine the extent of improvement simulator training provides to real-world operating theatre performance.

This multi-centre study will involve four cohorts of New Zealand orthopaedic trainees in their SET1 year. Trainees with no simulator exposure in 2019 - 2021 will form the comparator cohort. Trainees in 2022 will receive additional, regular simulator training as the intervention cohort. The comparator cohort's performance in paediatric SCHF surgery will be retrospectively audited using routinely collected operative outcomes and parameters over a six-month period. The performance of the intervention cohorts will be collected in the same way over a comparable period. The data collected for both groups will be used to examine whether additional training with an augmented reality simulator shows improved real-world surgical outcomes compared to traditional surgical training. This protocol has been approved by the University of Otago Health Ethics committee, and the study is due for completion in 2024.

This study is the first nation-wide transfer validity study of a surgical simulator in New Zealand. As of September 2022, all trainees in the intervention cohort have been recruited along with eight retrospective trainees via email. We present this protocol to maintain transparency of the prespecified research plans and ensure robust scientific methods. This protocol may also assist other researchers conducting similar studies within small populations.

Fractures through the physis account for 18–30% of all paediatric fractures, leading to growth arrest in 5.5% of cases. We have limited knowledge to predict which physeal fractures result in growth arrest and subsequent deformity or limb length discrepancy. The purpose of this study is to identify factors associated with physeal growth arrest to improve patient outcomes.

This prospective cohort study was designed to develop a clinical prediction model for growth arrest after physeal injury. Patients < 1 8 years old presenting within four weeks of injury were enrolled if they had open physes and sustained a physeal fracture of the humerus, radius, ulna, femur, tibia or fibula. Patients with prior history of same-site fracture or a condition known to alter bone growth or healing were excluded. Demographic data, potential prognostic indicators and radiographic data were collected at baseline, one and two years post-injury.

A total of 167 patients had at least one year of follow-up. Average age at injury was 10.4 years, 95% CI [9.8,10.94]. Reduction was required in 51% of cases. Right-sided (52.5%) and distal (90.1%) fractures were most common. After initial reduction 52.5% of fractures had some form of residual angulation and/or displacement (38.5% had both). At one year follow-up, 34 patients (21.1%) had evidence of a bony bridge on plain radiograph, 10 (6.2%) had residual angulation (average 12.6°) and three had residual displacement. Initial angulation (average 22.4°) and displacement (average 5.8mm) were seen in 16/34 patients with bony bridge (48.5%), with 10 (30.3%) both angulated and displaced. Salter-Harris type II fractures were most common across all patients (70.4%) and in those with bony bridges (57.6%). At one year, 44 (27.3%) patients had evidence of closing/closed physes.

At one year follow-up, there was evidence of a bony bridge across the physis in 21.1% of patients on plain film, and residual angulation and/or displacement in 8.1%. Initial angulation and/or displacement was present in 64.7% of patients showing possible evidence of growth arrest. The incidence of growth arrest in this patient population appears higher than past literature reports. However, plain film is an unreliable modality for assessing physeal bars and the true incidence may be lower. A number of patients were approaching skeletal maturity at time of injury and any growth arrest is likely to have less clinical significance in these cases. Further prospective long-term follow-up is required to determine the true incidence and impact of growth arrest.

The purpose of this study was to evaluate the results of simultaneous bilateral total hip and total knee arthroplasty performed in New Zealand during the first five years of the New Zealand National Joint Register and to determine whether this was an acceptable practice.

All total knee and total hip arthroplasties collected on the National Joint Register between 1999 and 2003 were divided into three groups – unilateral joint arthroplasty, staged bilateral joint arthroplasty and simultaneous joint arthroplasty. The Oxford 12 questionnaire results at six months were assessed as well as the patients self reported complications. All deaths that occurred within 6 months of the surgery were also recorded.

Analysis between the three groups was then performed using ANOVA tables comparing age, the Oxford scores and complications.

There was generally a significant difference (p< .001) in age between unilateral hip and knee replacement and staged or simultaneous bilateral replacement, with patients undergoing bilateral simultaneous replacement being younger.

There was a significant difference (p< .001) in the Oxford 12 scores between unilateral hip and knee replacement and both staged and simultaneous bilateral hip and knee replacement, with the bilateral simultaneous replacements scoring the best.

The death rate within the first 6 months was low in all groups with only 1 patient dying within 3 months of the surgery from an unrelated cause. The complication rate was low in all groups, in particular the DVT and pulmonary embolus rate, as reported by the patients, was not increased in either the sequential staged group or the simultaneous bilateral group.

The New Zealand National Joint Register has proven to be a valuable tool in gaining early information regarding the outcome following bilateral and staged lower limb total joint arthroplasty. The results clearly show that in the appropriate clinical situation performing simultaneous bilateral total knee or total hip arthroplasty is a safe and effective procedure.