With an ageing population and an increasing number of primary arthroplasties performed, the revision burden is predicted to increase. The aims of this study were to 1. Determine the revision burden in an academic hospital over a 11-year period; 2. identify the direct hospital cost associated with the delivery of revision service and 3. ascertain factors associated with increased cost.

This is an IRB-approved, retrospective, single tertiary referral center, consecutive case series. Using the hospital data warehouse, all patients that underwent revision hip or knee arthroplasty surgery between 2008-2018 were identified. 1632 revisions were identified (1304 patients), consisting of 1061 hip and 571 knee revisions. The majority of revisions were performed for mechanical-related problems and aseptic loosening (n=903; 55.3%); followed by periprosthetic joint infection (n=553; 33.9%) and periprosthetic fractures (176; 10.8%). Cost and length of stay was determined for all patient. The direct in-hospital costs were converted to 2020 inflation-adjusted Canadian dollars. Several patients- (age; gender; HOMR- and ASA-scores; Hemoglobin level) and surgical- (indication for surgery; surgical site) factors were tested for possible associations.

The number of revisions increased by 210% in the study period (2008 vs. 2018: 83 vs. 174). Revision indications changed over study period; with prevalence of fracture increasing by 460% (5 in 2008 vs. 23 in 2018) with an accompanying reduction in mechanical-related reasons, whilst revisions for infection remained constant. The mean annual cost over the entire study period was 3.9 MMCAD (range:2.4–5.1 MMCAD). The cost raised 150% over the study period from 2.4 MMCAD in 2008 to 3.6 MMCAD. Revisions for fractured had the greatest length of stay, the highest mean age, HOMR-score, ASA and cost associated with treatment compared to other revision indications (p < 0 .001). Patient factors associated with cost and length of stay included ASA- and HOMR-scores, Charlson-Comorbidity score and age.

The revision burden increased 1.5-fold over the years and so has the direct cost of care delivery. The increased cost is primarily related to the prolonged hospital stay and increased surgical cost. For tertiary care units, these findings indicate a need to identify strategies on improving efficiencies whilst improving the quality of patient care (e.g. efficient ways of reducing acute hospital stay) and reducing the raise of the economic burden on a publicly funded health system.

Short cementless femoral stems are increasingly popular as they allow for less dissection for insertion. Use of such stems with the anterior approach (AA) may be associated with considerable per-operative fracture risk. This study's primary aim was to evaluate whether patient-specific femoral- and pelvic- morphology and surgical technique, influence per-operative fracture risk. In doing so, we aimed to describe important anatomical thresholds alerting surgeons.

This is a single-center, multi-surgeon retrospective, case-control matched study. Of 1145 primary THAs with a short, cementless stem inserted via the AA, 39 periprosthetic fractures (3.4%) were identified. These were matched for factors known to increase fracture risk (age, gender, BMI, side, Dorr classification, stem offset and indication for surgery) with 78 THAs that did not sustain a fracture. Radiographic analysis was performed using validated software to measure femoral- (canal flare index [CFI], morphological cortical index [MCI], calcar-calcar ratio [CCR]) and pelvic- (Ilium-ischial ratio [IIR], ilium overhang, and ASIS to greater trochanter distance) morphologies and surgical technique (% canal fill). Multivariate and Receiver-Operator Curve (ROC) analysis was performed to identify predictors of fracture.

Femoral factors that differed included CFI (3.7±0.6 vs 2.9±0.4, p3.17 and II ratio>3 (OR:29.2 95%CI: 9.5–89.9, p<0.001).

Patient-specific anatomical parameters are important predictors of fracture-risk. When considering the use of short stems via the AA, careful radiographic analysis would help identify those at risk in order to consider alternative stem options.

Short cementless femoral stems are increasingly popular as they allow for less dissection for insertion. Use of such stems with the anterior approach (AA) may be associated with considerable per-operative fracture risk. This study's primary aim was to evaluate whether patient-specific femoral- and pelvic- morphology and surgical technique, influence per-operative fracture risk. In doing so, we aimed to describe important anatomical thresholds alerting surgeons.

This is a single-centre, multi-surgeon retrospective, case-control matched study. Of 1145 primary THAs with a short, cementless stem inserted via the AA, 39 periprosthetic fractures (3.4%) were identified. These were matched for factors known to increase fracture risk (age, gender, BMI, side, Dorr classification, stem offset and indication for surgery) with 78 THAs that did not sustain a fracture. Radiographic analysis was performed using validated software to measure femoral- (canal flare index [CFI], morphological cortical index [MCI], calcar-calcar ratio [CCR]) and pelvic- (Ilium-ischial ratio [IIR], ilium overhang, and ASIS to greater trochanter distance) morphologies and surgical technique (% canal fill). Multivariate and Receiver-Operator Curve (ROC) analysis was performed to identify predictors of fracture.

Femoral factors that differed included CFI (3.7±0.6 vs 2.9±0.4, p<0.001) and CCR (0.5±0.1 vs 0.4±0.1, p=0.006). The mean IIR was higher in fracture cases (3.3±0.6 vs 3.0±0.5, p<0.001). % Canal fill was reduced in fracture cases (82.8±7.6 vs 86.7±6.8, p=0.007). Multivariate analysis and ROC analyses revealed a threshold CFI of 3.17 was predictive of fracture (sensitivity:84.6% / specificity:75.6%). Fracture risk was 29 times higher when patients had CFI>3.17 and II ratio>3 (OR:29.2 95%CI: 9.5–89.9, p<0.001).

Patient-specific anatomical parameters are important predictors of fracture-risk. When considering the use of short stems via the AA, careful radiographic analysis would help identify those at risk in order to consider alternative stem options.

Management of acetabular fractures in the elderly population remains somewhat controversial in regards to when to consider is open reduction internal fixation (ORIF) versus acute primary total hip. study aims to (1) describe outcome of this complex problem and investigate predictors of successful outcome.

This retrospective study analyzes all acetabular fractures in patients over the age of 60, managed by ORIF at a tertiary trauma care centre between 2007 and 2018 with a minimum follow up of one year. Of the 117 patients reviewed, 85 patients undergoing ORIF for treatment of their acetabular fracture were included in the analysis. The remainder were excluded based management option including acute ORIF with THA (n=10), two-stage ORIF (n=2), external fixator only (n=1), acute THA (n=1), and conservative management (n=1). The remainder were excluded based on inaccessible medical records (n=6), mislabelled diagnosis (n=6), associated femoral injuries (n=4), acetabular fracture following hemiarthroplasty (n=1). The mean age of the cohort is 70±7 years old with 74% (n=62) of patients being male. Data collected included: demographics, mechanism of injury, Charlson Comorbidity Index (CCI), ASA Grade, smoking status and reoperations. Pre-Operative Radiographs were analyzed to determine the Judet and Letournel fracture pattern, presence of comminution and posterior wall marginal impaction. Postoperative radiographs were used to determine Matta Grade of Reduction. Outcome measures included morbidity-, mortality- rates, joint survival, radiographic evidence of osteoarthritis and patient reported outcome measures (PROMs) using the Oxford Hip Score (OHS) at follow-up. A poor outcome in ORIF was defined as one of the following: 1) conversion to THA or 2) the presence of radiographic OA, combined with an OHS less than 34 (findings consistent with a hip that would benefit from a hip replacement). The data was analyzed step-wise to create a regression model predictive of outcome following ORIF.

Following ORIF, 31% (n=26) of the cohort had anatomic reduction, while 64% (n=54) had imperfect or poor reduction. 4 patients did not have adequate postoperative radiographs to assess the reduction. 31 of 84 patients undergoing ORIF had a complication of which 22.6% (n=19) required reoperation. The most common reason being conversion to THA (n=14), which occurred an average of 1.6±1.9 years post-ORIF. The remainder required reoperation for infection (n=5). Including those converted to THA, 43% (n=36) developed radiographic OA following acetabular fracture management. The mean OHS in patients undergoing ORIF was 36 ± 10; 13(16%) had an OHS less than 34. The results of the logistic regression demonstrate that Matta grade of reduction (p=0.017), to be predictive of a poor outcome in acetabular fracture management. With non-anatomic alignment following fixation, patients had a 3 times greater risk of a poor outcome. No other variables were found to be predictive of ORIF outcome.

The ability to achieve anatomic reduction of fracture fragments as determined by the Matta grade, is predictive of the ability to retain the native hip with acceptable outcome following acetabular fracture in the elderly. Further research must be conducted to determine predictors of adequate reduction in order to identify candidates for ORIF.

The effectiveness of total hip replacement as a surgical intervention has revolutionized the care of degenerative conditions of the hip joint. However, the surgeon is still left with important decisions in regards to how best deliver that care with choice of surgical approach being one of them especially in regards to the short-term clinical outcome. It is however unclear if a particular surgical approach offers a long-term advantage. This study aims to determine the influence of the three main surgical approaches to the hip on patient reported outcomes and quality of life after 5 years post-surgery.

We extracted from our prospective database all the patients who underwent a Total Hip Replacement surgery for osteoarthritis or osteonecrosis between 2008 and 2012 by an anterior, posterior or lateral approach. All the pre-operative and post-operative HOOS (Hip disability and Osteoarthritis Outcome Score) and WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index) scores were noted. Analysis of covariance (ANCOVAs) were used to study the relationship between amount of change in HOOS and WOMAC subscales (dependant variables) and approach used, by also including confounding factors of age, gender, ASA (American Society of Anaesthesiologists) score, Charnley score and Body Mass Index. A total of 1895 patients underwent a primary total hip arthroplasty during the considered period. Among them, 367 had pre-operative and ≥5 years post operative PROM scores (19.47%)

The mean follow-up for the study cohort was 5.3 years (range 5 to 7 years) with, 277 at 5 years, 63 at 6 years, and 27 at 7 years. In the posterior approach group we had 138 patients (37.60%), 104 in the lateral approach (28.34%) and 125 in the anterior approach (34.06%). There were no significant differences between the 3 groups concerning the Charnley classification, BMI, Gender, ASA score, side and pre-operative functional scores. We did not observe any significant difference in the amount of change in HOOS and WOMAC subscales between the 3 groups. There were no differences either in the post-operative scores in ultimate value.

Our monocentric observational study shows that these three approaches provide predictable and comparable outcomes on HRQL and PROMs at long-term follow-up both in terms of final outcome but also in percent improvement. This study has several limitations. We excluded patients who underwent revision surgery leaving the unanswered question of how choice of surgical approach could lead to different revision rates, which have an impact on the functional outcomes. Moreover, even if we controlled for the most important confounders by a multivariate analysis model, there is still some involved cofounders, which could potentially lead to a bias such as smoking, socio-economical status or femoral head diameter. But we do not have any reason to think that these parameters could be unequally distributed between the three groups. Finally, our study cohort represents of 19.47% of the complete cohort. The fact that not all patients have PROM's was pre-determined as eight years ago we instituted that only 1 in 5 patients that returned their pre-operative questionnaire would get their PROM's at follow-up. Despite this, our statistical power was sufficient.

Background

Over 35% of surgeons in the United States, and 10% in Canada use the direct anterior approach for primary total hip arthroplasty (THA). Some of the key barriers in its wider adoption are the learning curve and associated increased risk of adverse events. The purpose of this study was to determine the adoption rate as well as 90-day re-admission and adverse event of the anterior approach in a community-based hospital.

Background

For total hip arthroplasty (THA), cognitive training prior to performing real surgery may be an effective adjunct alongside simulation to shorten the learning curve. This study sought to create a cognitive training tool to perform direct anterior approach THA, validated by expert surgeons; and test its use as a training tool compared to conventional material.

Background

Virtual Reality (VR) uses headsets and motion-tracked controllers so surgeons can perform simulated total hip arthroplasty (THA) in a fully-immersive, interactive 3D operating theatre. The aim of this study was to investigate the effect of laboratory-based VR training on the ability of surgical trainees to perform direct anterior approach THA on cadavers.

Aims

This study aims to: determine the difference in pelvic position that occurs between surgery and radiographic, supine, postoperative assessment; examine how the difference in pelvic position influences subsequent component orientation; and establish whether differences in pelvic position, and thereafter component orientation, exist between total hip arthroplasties (THAs) performed in the supine versus the lateral decubitus positions.

Introduction

The resultant cup orientation depends upon the orientation of the pelvis at impaction. No studies to date have assessed whether patient-position during total hip arthroplasty (THA) has an effect on cup orientation. This study aims to 1) Determine the difference in pelvic position that occurs between surgery and radiographic, supine, post-operative assessment; 2) Examine how the difference in pelvic position influences subsequent cup orientation and 3) Establish whether pelvic orientation, and thereafter cup orientation, differences exist between THAs performed in the supine versus the lateral decubitus positions.

Introduction

The mechanisms of how spinal arthrodesis (SA) affects patient function after total hip replacement (THA) remain unclear. The objectives of this study were to a) Determine how outcome post-THA compares between patients with- and without-SA, b) Characterize sagittal pelvic changes that occur when moving between different functional positions, and test for differences between patients with- and without-SA, and c) Assess whether differences in sagittal pelvic dynamics are associated with outcome post-THA.

The benefit of using a long intramedullary device for the treatment of geriatric intertrochanteric hip fractures is unknown. The InterTAN device (Smith and Nephew, Memphis TN) is offered in either Short (180–200 mm) or Long (260–460 mm) constructs and was designed to provide stable compression across primary intertrochanteric fracture fragments. The objective of our study was to determine whether Short InterTANs are equivalent to Long InterTANs in terms of functional and adverse outcomes for the treatment of geriatric intertrochanteric hip fractures.

108 patients with OTA classification 31A–1 and 31A–2 intertrochanteric hip fractures were included in our study and prospectively followed at one of four Canadian Level-1 Trauma Centres. Our primary outcomes included two validated primary outcome measures: the Functional Independence Measure (FIM), to measure function, and the Timed Up and Go (TUG), to measure motor performance. Secondary outcome measures included blood loss, length of procedure, length of stay and adverse events. A pre-injury FIM was measured by retrospective recall and all postoperative outcomes were assessed on postoperative day 3, at discharge, at 6 weeks, 3 months, 6 months and 12 months postoperatively. Unpaired t-tests and Chi-square tests were used for the comparison of continuous and categorical variables respectively between the Short and Long InterTAN groups. A statistically significant difference was defined as p<0.05.

Our study included 71 Short InterTAN and 37 Long InterTAN patients with 31A–1 and 31A–2 intertrochanteric hip fractures. Age, sex, BMI, side, living status and comorbidities were similar between the two groups. The mean operative time was significantly lower in the Short InterTAN group (61 mins) as compared to the Long InterTAN group (71 mins)(p0.05). There were 5 periprosthetic femur fractures in the short InterTAN group versus 1 in the long InterTAN group. Non-mechanical adverse outcomes such as myocardial infarction, pulmonary embolism, urinary tract infections, pneumonia and death all had similar incidence rates between the two InterTAN groups.

Both the Short and Long InterTAN patient cohorts displayed similar improvements in performance and overall function over the course of a year following intertrochanteric hip fracture fixation. The recorded operative times for Short InterTAN fixation were significantly shorter than those recorded for the Long InterTAN patients. Alternatively, a significantly higher proportion of Short InterTAN patients sustained periprosthetic femur fractures within a year of implantation as compared to the Long InterTAN group.

With the rapid evolution of surgical techniques every practicing surgeon will need to introduce new skills into their practice. Despite evidence that introducing a new surgical technique is associated with a learning curve during which there are reduced surgical and patient outcomes, there are no suggested protocols in place to support a surgeon in safely introducing a procedure into established practice. The purpose of this pilot study was to compare the effects of a mentored approach to learning new technical skills in practice to an unmentored approach.

A mentorship partnership and learning protocol was developed between a learning surgeon and an expert in the Direct Anterior Approach (DAA) total hip arthroplasty. After training in the technique the learning surgeon was directly supported in the first 3 cases and mentored for the first 15 cases.

Outcomes (surgical times, estimated blood loss, canal fit and fill, acetabular inclination and version, and complications) for the learning surgeons first 30 cases were assessed and compared to another learned cohort (first 30 cases of a percutaneously assisted total hip arthroplasty) integrated into practice without the support of a mentor. This data allow for the comparison of learning curves between the 2 techniques

Use of a mentored approach to the introduction of a new surgical skill was demonstrated to be a safe and more efficient than with an independent introduction of skills. The surgical times and learning curve were reduced and anectodatly the surgeons stress level was markedly reduced with a mentored approach. These findings support further work into surgical mentorship for the safe introduction of surgical skills in practice.

Traditional screw fixation of the syndesmosis can be prone to malreduction. Suture button fixation however, has recently shown potential in securing the fibula back into the incisura even with intentional malreduction. Yet, if there is sufficient motion to aid reduction, the question arises of whether or not this construct is stable enough to maintain reduction under loaded conditions. To date, there have been no studies assessing the optimal biomechanical tension of these constructs. The purpose of this study was to assess optimal tensioning of suture button fixation and its ability to maintain reduction under loaded conditions using a novel stress CT model.

Ten cadaveric lower limbs disarticulated at the knee were used. The limbs were placed in a modified external fixator frame that allows for the application of sustained torsional (5 Nm), axial (500 N) and combined torsional/axial (5Nm/500N) loads. Baseline CT scans of the intact ankle under unloaded and loaded conditions were obtaining. The syndesmosis and the deltoid ligament complex were then sectioned. The limbs were then randomised to receive a suture button construct tightened at 4 kg force (loose), 8 kg (standard), or 12 kg (maximal) of tension and CT scans under loaded and unloaded conditions were again obtained. Eight previously described measurements were taken from axial slices 10 mm above the tibiotalar joint to assess the joint morphology under the intact and repair states, and the three loading conditions: a measure of posterolateral translation (a, b), medial/lateral translation (c, g), a measure of anterior-posterior translation (f), a ratio of anterior-posterior translation (d/e), an angle (Angle 1) created by a line parallel to the incisura and the axis of the fibula, and an angle (Angle 2) created between the medial surfaces of two malleoli. These measurements have all been previously described. Each measurement was taken at baseline and compared with the three loading scenarios. A repeated measures ANOVA with a Bonferroni correction for multiple comparisons was used to test for significance.

Significant lateral (g, maximum 5.26 mm), posterior (f, maximum 6.42 mm), and external rotation (angle 2, maximum 11.71°) was noted with the 4 kg repair when compared to the intact, loaded state. Significant posterior translation was also seen with the both the 8 kg and 12 kg repairs, however the incidence and magnitude was less than with the 4 kg repair. Significant overcompression (g, 1.69 mm) was noted with the 12 kg repair.

Suture button constructs must be appropriately tensioned to maintain reduction and re-approximate the degree of physiological motion at the distal tibiofibular joint. If inserted too loosely, these constructs allow for supraphysiologic motion which may have negative implications on ligament healing. These constructs also demonstrate overcompression of the syndesmosis when inserted at maximal tension however the clinical effect of this remains to be determined.

Purpose: Preoperative planning forces the surgeon to understand the “fracture personality” and devise an operative plan. In our experience, trainees have difficulty in preparing for complex acetabular cases; these fractures are among the most difficult fractures to conceptualize and teach. As a result, these fractures are poorly understood as demonstrated by low interobserver agreement between trainees in the classification of acetabular fractures. We sought to determine whether the use of visou-haptic technology would help trainees to appreciate the “personality” of an Associated-Both-Column (ABC)fracture more accurately than trainees taught by conventional instruction.

Method: Thirty senior medical students and PGY1 residents, were randomized into two groups. The control group studied an ABC fracture with the aid of a textbook excerpt and a 3D CT reconstruction of the fracture. The intervention group was given the same instructional materials, and a visuo-haptic CT model of the fracture. All other learning variables, including time on task were standardized. Participants were evaluated on their accuracy in drawing the fracture lines on a model pelvis.

Results: There was no significant difference in gender, visuo-spatial ability, and training level between groups. The participants taught with the visuo-haptic model recalled an additional 26% anatomic relationships (p< 0.01) compared with the control group.

Conclusion: These findings suggest that in addition to the benefits observed in the learning of motor skills, visuo-haptic input may improve the understanding of spatial relationships. This technology may be a useful adjunct for teaching anatomy, as well as preoperative planning.

Purpose: To compare the accuracy of post-operative plain radiographs versus computed tomography (CT) scans for the assessment of acetabular fracture reduction.

Method: A retrospective assessment of sixty-four fractures in sixty-two patients was performed independently by three orthopedic trauma surgeons. Pre-operative CT scans and three plain radiographs (one anteroposterior pelvis and two Judet views) were used to classify the fracture pattern and measure pre-operative articular step and gap. Post-operative reduction quality was assessed using three plain radiographs and an axial CT assessing for step, gap, intra-articular hardware or fragments and necessity to re-operate.

Results: Fracture patterns were as follows; posterior wall (n=10), posterior column (n=1), anterior wall (n=4), anterior column (n=1), transverse (n=12), posterior column posterior wall (n=4), transverse posterior wall (n=8), T-type (n=6), anterior column posterior hemi-transverse (n=5) and associated both column (n=11). Pre-operatively, the average step and gap on plain radiographs was 8.7 mm (±SD) and 15.3 mm (±SD). Post-operatively, the average step and gap was 0.6 mm (SD) and 0.9 mm (SD) based on 46 patients. The assessment was not possible in 18 patients due to overlying hardware. Using plain radiographs, one patient was found to have an inadequate reduction (> 2mm step and/or > 3mm gap). Post-operative measurement of step and gap by CT scan were 1.2 mm (SD) and 2.3 mm (SD) respectively. Using CT scans, eight patients were found to have either an inadequate reduction, intra-articular hardware or retained fragments. Computed tomography demonstrated 2 times more step and gap compared to plain radiographs.

Conclusion: Post-operative CT was found to be more sensitive than plain radiographs to assess the quality of acetabular fracture reduction. Plain radiographs detected only 1 out of 8 cases where further operative intervention may have been beneficial. Given the consequences of missing an unacceptable reduction, intra-articular hardware, or retained intra-articular fragments, it is recommended that all fractures should be assessed postoperatively with CT unless the patient is not a candidate for further surgery for reasons independent of reduction quality. The benefits of post-operative CT imaging in acetabular fractures likely outweigh the cost and radiation exposure associated with its use.

Purpose: The purpose of this study was to review our results in patients with pilon fractures treated with ORIF in which surgical planning involved multiple skin incisions, ensuring that the distance incisions overlapped was less than the distance between them. We hypothesized that soft-tissue complications would be minimal despite incisions placed < 7-cm apart.

Method: A retrospective chart review identified 37 pilon fractures in 32 patients treated by three orthopedic traumatologists at The Ottawa Hospital between August 2000 and February 2007. Follow-up included measurements of incision placement and functional outcome measures.

Results: There were nine OTA type B and 28 OTA type C fractures; 28 were closed and nine were open. The mean age was 46.5 ±14.5 years, and average follow-up was 3.2 ±1.7 years. Of the patients reviewed, the average number of incisions was 3.7 ±1.1. The average overlap between incisions was 4.6-cm ±1.9 and the average skin bridge between incisions was 5.9-cm ±1.9, with 80% of the skin bridges < 7-cm. Average ROM was 4.3° ±7.1 dorsiflexion and 39.1° ±11.6 plantarflexion. The mean AMA lower extremity impairment score was 18.9% ±12.4, and mean SIP ambulation score was 9.6 ±8.8. Complications included two superficial infections, one deep infection, and three non-unions. There were no cases of wound dehiscence or necrosis, or cases requiring revision soft-tissue coverage. These outcomes were comparable to recent reports with similar injuries.

Conclusion: With careful planning and good soft-tissue management, incisions can be placed to maximize articular exposure based on fracture lines. It does not appear that the dogma of keeping incisions > 7-cm apart must be followed in most cases. Prudent surgical timing and meticulous soft-tissue handling can allow for multiple incisions to be placed as necessary for fracture reduction and optimal fixation while maintaining a low rate of complications.

Rapid advances in computer-assisted surgery (CAS) have lead to increasing integration of this technology into the orthopaedic training environment. The real-time feedback provided by CAS improves performance; however, it may be detrimental to learning. The primary purpose of this study is to determine if the form of feedback provided by computer-assisted technology (concurrent visual feedback) compromises the learning of surgical skills in the trainee.

Forty-five residents and senior medical students were randomised to one of three training groups and learned technical skills related to total hip replacement. The “Conventional Training” (CT) group self-determined acetabular cup position and were then corrected with traditional hand-over-hand repositioning. The “Computer Navigation” (CN) group used CAS to self-determine cup position. The “Knowledge of Results” (KR) group self-determined cup position and when satisfied used CAS for optimal repositioning. Outcomes (accuracy and precision of cup placement in abduction and anteversion, and time to position) were assessed in a pre-test, ten minute and six week retention and transfer tests. All retention and transfer tests were performed without CAS.

There were no differences between the groups at pre-test. All groups demonstrated an improvement in accuracy and precision of abduction angle and version angle determination during training (p < 0.001). The CN group demonstrated significantly better accuracy and precision in early training (p < 0.05), and better precision throughout training (p < 0.05). While the CN group demonstrated a decrease in precision during transfer testing it was not found to differ significantly from the other groups. No significant degradation in performance was observed between immediate and delayed testing for any group suggesting no negative effects of the tested training modalities on learning.

In this study the concurrent augmented feedback provided by CAS resulted in improved early performance without a compromise in learning, however, further investigation is required to ensure CAS does not compromise trainee learning. Until this issue is clarified, educators need to be aware of this potential effect.