Mid-term outcomes of bony increased offset-reverse total shoulder arthroplasty in the Asian population

Shoulder Physiological Offset Parameters in Asian Populations-A Magnetic Resonance Imaging Study

Background/Objectives: Physical shoulder offset parameters (SOPs) play important roles in the diagnosis and treatment of shoulder diseases. However, there is little research analyzing SOPs in healthy shoulders using cross-sectional MRI images, especially in Asians. Therefore, this study aimed to establish physiological reference values of shoulder parameters for Asian populations. Methods: This was a retrospective imaging study using MRI images of the shoulder joints of 500 patients (mean age: 55.9 ± 14.0 years). We measured the following SOPs of the normal joint: HO, GO, lateral glenoidal humeral offset (LGHO), humeral shaft axis offset (HAO), and cortical offset (CO). In addition, the offset parameters were examined for associations with age, gender, side, and osteoarthritis. Results: The mean HO was 22.9 (±2.4) mm, the mean GO was 62.3 (±6.6) mm, the mean LGHO was 48.9 (±4.2) mm, the mean HAO was 25.2 (±2.8) mm, and the mean CO was 15.7 (±2.7) mm. Male patients exhibited significantly higher values across all SOPs compared to female patients. In addition, there was a significantly lower mean value for HAO in left shoulders (HAO: 24.7± 2.8 mm vs. 25.5 ± 2.8 mm, p = 0.011). There was a negatively significant correlation between age and all SOPs. No significant difference in mean values was noted between shoulders with osteoarthritis and non-osteoarthritis in any SOPs. Conclusions: Significant gender- and age-specific differences were noted for all measured SOPs. In addition, right shoulders did not show higher mean SOP values than left shoulders, except for HAO, suggesting that the contralateral joint is a reliable reference for surgical planning. These findings should be considered in shoulder surgery planning.

Clinical and radiological outcomes with an augmented baseplate for superior glenoid wear in reverse shoulder arthroplasty

Aims

This study aimed to assess the impact of using the metal-augmented glenoid baseplate (AGB) on improving clinical and radiological outcomes, as well as reducing complications, in patients with superior glenoid wear undergoing reverse shoulder arthroplasty (RSA).

Methods

From January 2016 to June 2021, out of 235 patients who underwent primary RSA, 24 received a superior-AGB after off-axis reaming (Group A). Subsequently, we conducted propensity score matching in a 1:3 ratio, considering sex, age, follow-up duration, and glenoid wear (superior-inclination and retroversion), and selected 72 well-balanced matched patients who received a standard glenoid baseplate (STB) after eccentric reaming (Group B). Superior-inclination, retroversion, and lateral humeral offset (LHO) were measured to assess preoperative glenoid wear and postoperative correction, as well as to identify any complications. Clinical outcomes were measured at each outpatient visit before and after surgery.

Results

There were no significant differences in demographic data and preoperative characteristics between the two groups. Both groups showed significant improvements in patient-reported outcome measures (visual analogue scale for pain, visual analogue scale for function, American Shoulder and Elbow Surgeons, Constant, and Simple Shoulder Test scores) from preoperative to final assessment (p < 0.001). However, AGB showed no additional benefit. Notably, within range of motion, Group B showed significant postoperative decrease in both external rotation and internal rotation, unlike Group A (p = 0.028 and 0.003, respectively). Both groups demonstrated a significant correction of superior-inclination after surgery, while patients in Group B exhibited a significant decrease in LHO postoperatively (p = 0.001). Regarding complications, Group A experienced more acromial stress fractures (3 cases; 12.5%), whereas Group B had a higher occurrence of scapular notching (24 cases; 33.3%) (p = 0.008).

Conclusion

Both eccentric reaming with STB and off-axis reaming with AGB are effective methods for addressing superior glenoid wear in RSA, leading to improved clinical outcomes. However, it is important to be aware of the potential risks associated with eccentric reaming, which include excessive bone loss leading to reduced rotation and scapular notching.

Comparable outcomes of reverse shoulder arthroplasty for proximal humerus fractures and for rotator cuff arthropathy in a predominantly asian population

Background

Reverse shoulder arthroplasty (RSA) was initially developed for rotator cuff arthropathy but has been expanded to treat comminuted proximal humerus fractures. Few studies have compared RSA for traumatic and degenerative indications. We present the first report of mid-term outcomes of RSA comparing both indications in an Asian population.

Methods

113 degenerative and 20 fracture patients underwent RSA from 2010 to 2019. Patients with degenerative indications were 4:1 propensity-score matched to fractures and adjusted for age and sex. Patients were assessed for range of motion (ROM), strength, pain, Constant-Murley score (CMS), University of California Los Angeles Shoulder Score (UCLA) and Oxford shoulder score (OSS) preoperatively, at 6-months and 1-year. Patients' satisfaction, expectation fulfilment and minimal clinically important difference (MCID) were analysed.

Results

Degenerative patients had better ROM, isometric strength and CMS at 6-months, although at 1-year only abduction was superior (104.8  ±  17.3° vs 86.7  ±  19.8°). No significant differences in pain, UCLA and OSS were observed. Most improvements occurred within 6 months. Similar proportions of patients were satisfied (83.3% vs 73.3%, p = 0.460) and attained MCID (85.0% vs 86.7%, p = 1.000) at 1-year.

Discussion

Although initially exhibiting slower recovery, patients with proximal humerus fractures can expect similar functional recovery and satisfaction at 1-year compared to those who received RSA for degenerative indications.