Stable glenoid component of reverse total shoulder arthroplasty at 2 years as measured with model-based radiostereometric analysis (RSA).

Background and purpose - Reverse total shoulder arthroplasty (TSA) is used for treating cuff arthropathy, displaced proximal humeral fractures (PHF), and in revision shoulder surgery, despite sparse evidence on long-term results. We assessed stability of the glenoid component in reverse TSA, using model-based RSA.Patients and methods - 20 patients (mean age 76 years, 17 female), operated on with reverse TSA at Oslo University Hospital, in 2015-2017 were included. Indications for surgeries were PHFs, malunion, cuff arthropathy, and chronic shoulder dislocation. RSA markers were placed in the scapular neck, the coracoid, and the acromion. RSA radiographs were conducted postoperatively, at 3 months, 1 year, and 2 years. RSA analysis was performed using RSAcore with Reversed Engineering (RE) modality, with clinical precision < 0.25 mm for all translations (x, y, z) and < 0.7° for rotations (x, z). Scapular "notching" was assessed in conventional radiographs.Results - 1 patient was excluded due to revision surgery. More than half of the patients displayed measurable migration at 2 years: 6 patients with linear translations below 1 mm and 8 patients who showed rotational migration. Except for one outlier, the measured rotations were below 2°. The migration pattern suggested implant stability at 2 years. 10 patients showed radiolographic signs of "notching", and the mean Oxford Shoulder Score (OSS) at 2 years was 29 points (15-36 points).Interpretation - Stability analysis of the glenoid component of reversed total shoulder arthroplasty using reversed engineering (RE) model-based RSA indicated component stability at 2 years.

Pegs not superior to screws for fixation of fractures of the proximal humerus.

BACKGROUND: Angular stable plates were introduced two decades ago as a promising treatment for fixation of displaced fractures of the proximal humerus (PHF). However, high rates of adverse events and reoperations have been reported. One frequent reason is secondary penetration of screws into the glenohumeral joint, due to sinking of the fracture or avascular head necrosis. To prevent joint penetrations angular stable plates with smooth locking pegs instead of locking screws have been developed. The aim of the present study was to investigate whether blunt pegs instead of pointed screws reduced the risk of secondary penetration into the glenohumeral joint during fracture healing after operatively treated PHFs. METHODS: From two different patient cohorts with displaced PHFs (60 treated with PHILOS plate with screws and 50 with ALPS-PHP plate with pegs), two groups were matched according to fracture type AO/OTA 11-B2 and 11-C2 and age (55-85 years). They were followed up at 3, 6 and 12 months. Primary outcome was radiographic signs of peg or screw penetrations into the glenohumeral joint at 12 months. Secondary outcomes were Oxford shoulder score (OSS) and Constant Score (CS) and radiographic signs of avascular humeral head necrosis (AVN). RESULTS: Eighteen PHILOS patients with B2 and C2 fractures could be matched with a corresponding group of 18 operated with ALPS-PHP with pegs. The number of penetrations of pegs and screws were equal between the two groups and the development of avascular head necrosis did not differ either. The functional outcomes for both OSS and CS at 12 months was clearly in favor of patients without joint penetrations in both groups. CONCLUSION: We found no differences in the number of screw or peg penetrations in the PHILOS and ALPS-PHP group and the occurrence of AVN was equal. Joint penetrations led to inferior functional outcomes at 1 year. The ClinicalTrials.gov identifier 20/11/12 prospectively for the Philos Group is NCT01737060, and for the ALPS group 11/03/20 retrospectively is NCT04622852.

Reverse Shoulder Arthroplasty Is Superior to Plate Fixation at 2 Years for Displaced Proximal Humeral Fractures in the Elderly: A Multicenter Randomized Controlled Trial.

BACKGROUND: Almost one-third of patients with proximal humeral fractures are treated surgically, and the number is increasing. When surgical treatment is chosen, there is sparse evidence on the optimum method. The DelPhi (Delta prosthesis-PHILOS plate) trial is a clinical trial comparing 2 surgical treatments. Our hypothesis was that reverse total shoulder arthroplasty (TSA) yields better clinical results compared with open reduction and internal fixation (ORIF) using an angular stable plate. METHODS: The DelPhi trial is a randomized controlled trial comparing reverse TSA with ORIF for displaced proximal humeral fractures (OTA/AO types 11-B2 and 11-C2) in elderly patients (65 to 85 years of age). The primary outcome measure was the Constant score at a 2-year follow-up. The secondary outcome measures included the Oxford Shoulder Score and radiographic evaluation. Results were reported as the mean difference with 95% confidence interval (CI). The intention-to-treat principle was applied for crossover patients. RESULTS: There were 124 patients included in the study. At 2 years, the mean Constant score was 68.0 points (95% CI, 63.7 to 72.4 points) for the reverse TSA group compared with 54.6 points (95% CI, 48.5 to 60.7 points) for the ORIF group, resulting in a significant mean difference of 13.4 points (95% CI, 6.2 to 20.6 points; p < 0.001) in favor of reverse TSA. When stratified for fracture classification, the mean score was 69.3 points (95% CI, 63.9 to 74.7 points) for the reverse TSA group and 50.6 points (95% CI, 41.9 to 59.2 points) for the ORIF group for type-C2 fractures, which yielded a significant mean difference of 18.7 points (95% CI, 9.3 to 28.2 points; p < 0.001). In the type-B2 fracture group, the mean score was 66.2 points (95% CI, 58.6 to 73.8 points) for the reverse TSA group and 58.5 points (95% CI, 49.6 to 67.4 points) for the ORIF group, resulting in a nonsignificant mean difference of 7.6 points (95% CI, -3.8 to 19.1 points; p = 0.19). CONCLUSIONS: At a 2-year follow-up, the data suggested an advantage of reverse TSA over ORIF in the treatment of displaced OTA/AO type-B2 and C2 proximal humeral fractures in elderly patients. LEVEL OF EVIDENCE: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Model-based RSA is suitable for clinical trials on the glenoid component of reverse total shoulder arthroplasty.

This study aims to validate model-based radiostereometric analysis (RSA) on the glenoid component of reversed total shoulder arthroplasty. We compared two different modalities of model-based RSA, elementary geometrical shapes and reversed engineering. We also explored two different ways to position the patient to obtain different projections of the implant, the hip-position (transversal) and shoulder-position (sagittal). Phantom accuracy was determined by performing nine translations (x, y, z) and five rotations (x, y, z), and expressed as the mean difference between RSA measurements and micrometer values. Precision was measured using 12 double examinations of the phantom and 19 in patients, and expressed as1.96 × standard deviations of the paired differences between double examinations. The accuracy was high for both modalities, but rotation around the symmetrical axis of the implant could not be measured using reversed engineering. Clinical precision ranged from 0.13 to 0.25 mm for translations, and 0.4° to 0.7° for rotations, using reversed engineering. For elementary geometrical shapes, the precision ranged from 0.18 to 0.34 mm for translations, and 0.8° to 1.8° for rotations. The hip-position was abandoned due to poor implant visualization. Model-based RSA on the glenoid component of reversed total shoulder arthroplasty has a high precision and accuracy, comparable to RSA results on hips and knees. Patient positioning is vital for obtaining adequate results. We found that reversed engineering was the more reliable method, and recommend reversed engineering as the method of choice for further clinical RSA investigation of the glenoid component of reversed total shoulder arthroplasty. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:3299-3307, 2018.