Lower operating volume in shoulder arthroplasty is associated with increased revision rates in the early postoperative period: long-term analysis from the Australian Orthopaedic Association National Joint Replacement Registry.

BACKGROUND: Improved short-term outcomes have been demonstrated with higher surgical volume in shoulder arthroplasty. There is however, little data regarding long-term outcomes. METHOD: Revision data from the Australian Orthopaedic Association National Joint Replacement Registry from 2004-2017 was analyzed according to 3 selected surgeon volume thresholds: <10, 10-20, and >20 shoulder arthroplasty cases per surgeon, per year. RESULTS: There was a significantly higher rate of revision for stemmed total shoulder arthroplasty (TSA) for osteoarthritis (OA) for the <10/yr compared with the >20/yr group for the first 1.5 years only (hazard ratio [HR] 1.36, 95% confidence interval [CI] 1.08-1.71, P = .009). For reverse total shoulder arthroplasty (rTSA) performed for OA, there was a higher revision rate for the <10/yr compared with the >20/yr group for the first 3 months only (HR 2.58, 95% CI 1.67-3.97, P < .001). In rTSA for cuff arthropathy, there was a significantly higher rate of revision for the <10/yr compared with the >20/yr group throughout the follow-up period (HR 1.66, 95% CI 1.21-2.28, P = .001). There was no significant difference for the primary diagnosis of fracture. CONCLUSION: Lower surgical volume was associated with higher all-cause revision rates in the early postoperative period in TSA and rTSA for OA and throughout the follow-up period in rTSA for cuff arthropathy. Despite increases in the volume of shoulder arthroplasties performed in recent years, more than 78% of surgeons undertake fewer than 10 procedures per year.

Defining the errors in the registration process during imageless computer navigation in total knee arthroplasty: a cadaveric study.

Computer assisted arthroplasty was introduced as a means to optimally align implants in order to improve function and longevity. The error during the manual registration of landmarks and its effect on component alignment was investigated in this study. Five fresh frozen lower limbs were used and the registration process was performed five times by five surgeons. The error range of the mechanical axis of the femur in the coronal plane was 5.2 degrees of valgus to 2.9 degrees of varus whilst the transepicondylar axis error was 11.1 degrees of external to 6.3 of internal rotation. Those figures suggest that the registration error alone can have a significant effect on the alignment of the implant.

Computer-assisted navigation for the assessment of fixed flexion in knee arthroplasty.

BACKGROUND: Correction of a fixed flexion deformity is an important goal when performing total knee arthroplasty. The purpose of this study was to assess the accuracy of clinical assessment compared with imageless computer navigation in determining the degree of fixed flexion. METHODS: We performed navigation anatomy registration using 14 cadaver knees.The knees were held in various degrees of flexion with 2 crossed pins. The degree of flexion was first recorded on the computer and then on lateral radiographs. The cadaver knees were draped as they would be for a total knee arthroplasty, and 9 examiners were asked to clinically assess by visual observation the amount of fixed flexion.Three examiners repeated the process 1 week later. RESULTS: The mean error from the radiographs in the navigation group was 2.18 degrees (95% confidence interval [CI] 1.23 degrees -3.01 degrees) compared with 5.57 degrees (95% CI 4.86 degrees -6.29 degrees) in the observer group. The navigation was more consistent, with a range of error of -5 degrees to +5.5 degrees compared with -18.5 degrees to +17.5 degrees in the observer group. The observers tended to underestimate the amount of knee flexion (median error -4 degrees), whereas the navigation group was more evenly distributed (median error 0). The highest concordance coefficient was found between navigation and radiography (0.96). The concordance coefficient was 0.88 for the 3 surgeons who repeated the measurements 1 week later (mean error 3.5 degrees , range 15 degrees ). CONCLUSION: The use of computer navigation appears to be a more accurate method for assessing the degree of knee flexion, with a reduced range of error compared with clinical assessment. The use of computer-assisted surgery may therefore provide surgeons with the information required to more consistently restore full extension during total knee arthroplasty.

A comparison of registration errors with imageless computer navigation during MIS total knee arthroplasty versus standard incision total knee arthroplasty: a cadaveric study.

Optimal component alignment in total knee arthroplasty has been associated with better functional outcome as well as improved implant longevity. The ability to align components optimally during minimally invasive (MIS) total knee replacement (TKR) has been a cause of concern. Computer navigation is a useful aid in achieving the desired alignment although it is limited by the error during the manual registration of landmarks. Our study aims to compare the registration process error between a standard and a MIS surgical approach. We hypothesized that performing the registration error via an MIS approach would increase the registration process error. Five fresh frozen lower limbs were routinely prepared and draped. The registration process was performed through an MIS approach. This was then extended to the standard approach and the registration was performed again. Two surgeons performed the registration process five times with each approach. Performing the registration process through the MIS approach was not associated with higher error compared to the standard approach in the alignment parameters of interest. This rejects our hypothesis. Image-free navigated MIS TKR does not appear to carry higher risk of component malalignment due to the registration process error. Navigation can be used during MIS TKR to improve alignment without reduced accuracy due to the approach.