Reverse total shoulder arthroplasty with combined deltoid reconstruction in patients with anterior and/or middle deltoid tears

Spontaneous Deltoid Tear in Cuff Tear Arthropathy and Its Effect on the Outcome of Reverse Total Shoulder Arthroplasty: A Comparison Using Propensity Score Matching

Background

Deltoid function critically influences the results of reverse total shoulder arthroplasty (RTSA), and spontaneous deltoid attrition tears are frequently detected in cuff tear arthropathy (CTA) patients; however, the clinical impacts of these tears on RTSA outcomes are undetermined. Our aim was to determine the effect of spontaneous deltoid attrition tears on postoperative outcomes after RTSA without an additional deltoid procedure.

Methods

Seventy-two patients who underwent RTSA for CTA with preoperative magnetic resonance imaging (MRI) and a minimum clinical follow-up of 1 year (mean, 32 months) were retrospectively reviewed in the study. Patients with a history of previous shoulder surgery or injury were excluded. The presence and location of deltoid attrition tears were determined in preoperative MRI. Propensity score matching (1:1) was performed to construct tear and no-tear groups. Finally, 21 patients, matched with respect to age, sex, hand dominance, symptom duration, medical comorbidity (obesity, diabetes mellitus, and coronary artery disease), Hamada grade, and implant type, were assigned to each group. Clinical outcomes (functional scores, isometric power, and range of motion) in the two groups were compared.

Results

Deltoid attrition tears were detected in 21 of the 72 enrolled cases (29.1%). Anterolateral deltoid was the most frequent location and no tear was detected in the posterior deltoid. The tear rate increased with disease severity (Hamada G2, 4.8%; G3, 23.8%; > G4, 71.4%). No pre- or postoperative clinical variables differed significantly between the tear and no tear groups.

Conclusions

Deltoid attrition tears were detected in 29% of CTA patients who underwent RTSA. The most common site was the anterolateral region and tear prevalence tended to increase with CTA progression. However, RTSA was found to provide satisfactory outcomes regardless of the presence of a deltoid attrition tear.

The lateralization and distalization shoulder angles are important determinants of clinical outcomes in reverse shoulder arthroplasty

BACKGROUND

Reverse shoulder arthroplasty (RSA) designs vary in the lateralization and distalization geometry, which may affect functional outcomes. The purpose was to determine the effect of RSA lateralization and distalization on final functional outcomes by using the "lateralization shoulder angle" (LSA) and the "distalization shoulder angle" (DSA).

METHODS

Forty-six consecutive patients who underwent RSA for cuff tear arthropathy were retrospectively evaluated. Functional outcome and radiographs were evaluated at a minimum of 2 years postoperatively and compared between implants with or without glenoid lateralization and with or without humeral-sided lateralization. Anteroposterior shoulder radiographs were used to evaluate the LSA and DSA.

RESULTS

Both angles showed substantial to almost perfect intrarater and inter-rater agreement. Higher LSA values were found in more lateralized RSAs (P = .027), and values between 75° and 95° were correlated with better active external rotation (quadratic regression analysis R² = 0.553, P < .001). Postoperative active anterior elevation (R² = 0.2, P = .008), Constant (r_s = 0.29, P = .05), and Activities of Daily Living Requiring External Rotation scores (r_s = 0.4 P = .007) had a positive correlation with the LSA. The quadratic regression analysis also showed that a DSA between 40° and 65° resulted in better active anterior elevation (R² = 0.4, P < .001) and abduction (R² = 0.4, P < .001). The negative correlation between the LSA and DSA (r_s = -0.7, P < .001) revealed that, according to the implant used, the more distally the RSA is placed the less lateralization is achieved.

CONCLUSIONS

The LSA and the DSA are reproducible measurements that may be used to estimate "lateralization and distalization" after RSA. These measurements are correlated with postoperative clinical outcomes.