Reversed total shoulder arthroplasty for rotator cuff arthropathy is associated with increased scapulothoracic motion: A longitudinal two-year kinematic study.

BACKGROUND: Reversed total shoulder arthroplasty (RTSA) is a standard surgical procedure for the treatment of rotator cuff tear arthropathy (CTA), aimed at restoring active arm elevation. Shoulder elevation relies on both scapulothroacic (ST) and glenohumeral (GH) motion, but RTSA computer planning primarily focuses on the GH joint due to challenges in visualizing scapulothroacic (ST) motion. RESEARCH QUESTION: Does the scapulohumeral rhythm, by means of the relative contributions of ST rotation and GH elevation per degree of arm elevation, in a longitudinal setting for up to two years postoperatively after RTSA for CTA change? METHODS: In a prospective longitudinal study, shoulder kinematics were studied in 20 patients (22 shoulders) before and at three, six, 12, and 24 months after RTSA implantation for CTA. Skin markers were tracked using 3D motion analysis. The relative ST and GH contributions per degree of arm elevation were assessed and were compared using statistical non-parametric mapping with Bayesian inference. RESULTS: Mean arm elevation was 89 ± 33° preoperatively, 135 ± 28° at 3 months, 161 ± 20° at 6 months, 169 ± 18° at 12 months, and 165 ± 19° at 24 months. Between 48-66°, 62-93°, 53-94°, 60-97° and 72-104° of arm elevation at the measurement time points pre, 3-months, 6-months, 12-months and 24-months postoperatively, respectively, the ST rotation had a significantly greater contribution to arm elevation compared to GH elevation; a pattern that was not found in controls. SIGNIFICANCE: While RTSA successfully restored active arm elevation through improved GH and ST motion, the scapulohumeral rhythm exhibited a consistent pattern up to two years postoperatively, resembling the preoperative state. In the midrange of motion, ST rotation dominated over GH elevation, potentially contributing to muscular fatigue and explaining the documented decline in functional outcomes over time after RTSA. The findings highlight the importance of incorporating ST kinematics into modern computer planning for RTSA.

The effects of length and width of the stem on proximal humerus stress shielding in uncemented primary reverse total shoulder arthroplasty.

INTRODUCTION: To preserve humeral bone during RTSA, stems have been made shorter and cement avoided whenever possible. However, with the increased use of uncemented RTSA, a phenomenon comparable to the stress shielding of the hip has been described for the proximal humerus. The aim of this study was to investigate the influence of stem length and width on proximal humeral bone resorption after primary uncemented RTSA. MATERIALS AND METHODS: The prospective shoulder arthroplasty database of our institution was reviewed for all primary uncemented RTSAs from 2017 to 2020 in osteoarthritis and cuff tear arthropathy cases with > 2-year follow-up. We compared the clinical and the radiographic 2-year outcome of the short and standard length stems of the same prosthesis design. This allowed us to assess the effects of stem length and width with regard to stress shielding. Furthermore, we defined a cut-off value for the filling ratios to prevent stress shielding. RESULTS: Fifty patients were included in the analysis, nineteen were in the short stem group (SHORT) and thirty-one in the standard stem group (STANDARD). After 2 years, SHORT showed a relative Constant Score of 91.8% and STANDARD of 98.3% (p = 0.256). Stress shielding was found in 4 patients (21%) in SHORT and in 16 patients (52%) in STANDARD (p = 0.03); it occurred more frequently in patients with higher humeral filling ratios (p < 0.05). The calculated cut-off to prevent stress shielding was 0.7 (± 0.03) for the metaphyseal and distal filling ratio. CONCLUSION: While short and standard stems for RTSA have good results after 2 years, we found a significant negative effect of higher length and width of the stem with regard to stress shielding. Even though the clinical effects of stress shielding have to be assessed, short stems should be chosen with a filling ratio at the metaphyseal and distal position below 0.7. LEVEL OF EVIDENCE (A RETROSPECTIVE CASE-CONTROL STUDY): III.

Cemented vs. uncemented reverse total shoulder arthroplasty for the primary treatment of proximal humerus fractures in the elderly-a retrospective case-control study.

BACKGROUND: Uncemented reverse total shoulder arthroplasty (RTSA) for the primary treatment of proximal humerus fractures (PHF) in elderly patients was introduced at our institution in 2017. Recent reports have raised concerns about increased rates of early bone resorption at the proximal humerus with uncemented fracture stems. The aim of this study was to find out whether there was any difference in functional or radiographic outcomes between cemented and uncemented RTSA for PHF. METHODS: Seventeen consecutive patients who underwent uncemented RTSA (group nC) in 2017 and 2018 were age and sex matched (propensity score matching 1:2) to 34 patients with cemented RTSA implanted between 2011 and 2016 (group C) for the primary treatment of PHF. These two groups were compared in terms of clinical and radiographic outcomes at 2 years after the index surgery. RESULTS: The mean bone quality was low in both groups: in group nC the deltoid tuberosity index (DTI) was 1.43 (1.22-1.72) and in group C 1.42 (1.22-1.67). At the final 2 year follow-up, the relative CS was 98.3% (71-118) in group nC and 97.9% (36-125) in group C (p = 0.927); the absolute CS was 70.2 (49-89) in group nC and 68.0 (30-94) in group C (p = 0.509). Lucent lines at the humeral site were seen in 8 cases (47%) in group nC and in 13 cases (38%) in group C (p = 0.056). Compared to 3% in group C, all patients in group nC showed at least grade 1 and 65% showed grade 3 bone resorption at the proximal humerus (p < 0.001). CONCLUSION: Compared to cemented RTSA bone resorption at the proximal humerus was significantly more frequent in patients with uncemented RTSA for PHF. So far, this is rather a radiographic than a clinical finding, because both groups showed very satisfying functional outcomes and low revision rates at the 2 year follow-up. LEVEL OF EVIDENCE III: A retrospective case-control study.

Clinical and radiological outcome at mean follow-up of 11 years after hip arthroscopy.

INTRODUCTION: The use of hip arthroscopy (HA) has substantially increased over the last decade. However, while the benefits of HA after 1 year in patients with femoroacetabular impingement (FAI) are well documented, long-term data on the progression of osteoarthritis (OA) or patient-reported outcomes (PROMs) are lacking. OBJECTIVES: To evaluate long-term clinical and radiological outcomes after HA. MATERIALS AND METHODS: Preoperative clinical records, operative notes, and radiographs from all patients who underwent HA at our hospital between 1998 and 2006 were reviewed. Exclusion criteria were previous hip surgery or diagnostic HA. Primary endpoints were subsequent total hip arthroplasty (THA) or other hip surgery. Secondary endpoints were OA progression and PROMs. RESULTS: HA was performed in 92 consecutive patients from 1998 to 2006. Indications for HA were FAI, labral lesions, early OA, and focal osteochondral defects. Mean follow-up was 11.2 years (SD 2.5, range 7.9-16). Data from 43 patients were available for analysis; 38 patients were excluded, and 11 were lost to follow-up. 20 patients had subsequent hip surgery, of which 11 patients required THA. 33 patients (77%) stated that they would undergo HA again under the same circumstances. Longitudinal radiological analysis showed no significant OA progression in patients without THA. The Forgotten Joint Score-12 was the only PROM to significantly differ between patients who had no further surgery and patients who had undergone revision (p = 0.037). CONCLUSION: There was no significant OA progression on plain radiography at an average of 11 years post-HA. Sound indication criteria is essential, as 45% of patients required subsequent surgery.