Analysis of three different reverse shoulder arthroplasty designs for cuff tear arthropathy - the combination of lateralization and distalization provides best mobility.

BACKGROUND: The two major reverse shoulder arthroplasty (RSA) designs are the Grammont design and the lateralized design. Even if the lateralized design is biomechanically favored, the classic Grammont prosthesis continues to be used. Functional and subjective patient scores as well as implant survival described in the literature so far are comparable to the lateralized design. A pure comparison of how the RSA design influences outcome in patients has not yet been determined. The aim of this study was a comparison focused on patients with cuff tear arthropathy (CTA). METHODS: We analyzed registry data from 696 CTA patients prospectively collected between 2012 and 2020 in two specialized orthopedic centers up to 2 years post-RSA with the same follow-up time points (6,12 24 months). Complete teres minor tears were excluded. Three groups were defined: group 1 (inlay, 155° humeral inclination, 36 + 2 mm eccentric glenosphere (n = 50)), group 2 (inlay, 135° humeral inclination, 36 + 4 mm lateralized glenosphere (n = 141)) and group 3 (onlay, 145° humeral inclination, + 3 mm lateralized base plate, 36 + 2 mm eccentric glenosphere (n = 35)) We compared group differences in clinical outcomes (e.g., active and passive range of motion (ROM), abduction strength, Constant-Murley score (CS)), radiographic evaluations of prosthetic position, scapular anatomy and complications using mixed models adjusted for age and sex. RESULTS: The final analysis included 226 patients. The overall adjusted p-value of the CS for all time-points showed no significant difference (p = 0.466). Flexion of group 3 (mean, 155° (SD 13)) was higher than flexion of group 1 (mean, 142° (SD 18) and 2 (mean, 132° (SD 18) (p < 0.001). Values for abduction of group 3 (mean, 145° (SD 23)) were bigger than those of group 1 (mean, 130° (SD 22)) and group 2 (mean, 118° (SD 25)) (p < 0.001). Mean external rotation for group 3 (mean, 41° (SD 23)) and group 2 (mean, 38° (SD 17)) was larger than external rotation of group 1 (mean, 24° (SD 16)) (p < 0.001); a greater proportion of group 2 (78%) and 3 (69%) patients reached L3 level on internal rotation compared to group 1 (44%) (p = 0.003). Prosthesis position measurements were similar, but group 3 had significantly less scapular notching (14%) versus 24% (group 2) and 50% (group 1) (p = 0.001). CONCLUSIONS: Outcome scores of different RSA designs for CTA revealed comparable results. However, CTA patients with a lateralized and distalized RSA configuration were associated with achieving better flexion and abduction with less scapular notching. A better rotation was associated with either of the lateralized RSA designs in comparison with the classic Grammont prosthesis. LEVEL OF EVIDENCE: Therapeutic study, Level III.

Complications and Revisions in Metal-Backed Anatomic Total Shoulder Arthroplasty: A Comparative Study of Revision Rates Between Stemless and Stemmed Humeral Components.

BACKGROUND: The primary objective of this study was to evaluate and compare the incidence of complications and revision surgeries between in two of convertible metal-back glenoid systems in total shoulder arthroplasty (aTSA) groups over a follow-up period of up to five years. METHODS: A retrospective analysis included 69 shoulders from 65 patients with primary aTSA. Patients were divided into Group 1 (n=31), receiving convertible cementless stemmed aTSA (Lima SMR) and Group 2 (n=38), receiving humeral head replacement aTSA (Arthrex, Eclipse) both with metal-back glenoid components. Clinical and radiological assessments were conducted at 2, 5, and 10 years postoperatively. Assessments included the following: Constant Score, DASH, SPADI, SSV, Glenohumeral Distance, Critical Shoulder Angle and Lateral Acromion Index. In addition, we compared complications, revision rates and survival rates between groups using Kaplan-Maier curves and Log-Rank-test. RESULTS: Baseline demographics and preoperative outcome scores showed no significant differences between groups (p≥0.05). The overall revision rate did not significantly differ between groups (Group 1:32% vs. Group 2:24%, p=0.60), nor did the mean time to revision (p=0.27). The mean follow-up was 71±41 months (Group 1: 94±48 months, Group 2: 53±23 months, p<0.001). Kaplan-Meier analysis showed similar mid-term survival probabilities (p=0.94). Revision reasons included rotator cuff insufficiency (n=4 in Group 1, n=2 in Group 2) and glenoid wear/loosening (n=5 in Group 1, n=7 in Group 2). Interestingly, Group 1 demonstrated no occurrence of glenoid metal baseplate or humeral loosening, while complex revisions were more common in the Group 2. At 2 and 5 years, non-revised patients in both groups had similar outcome scores. CONCLUSION: Metal-backed glenoid implants in combination with both stemless and stemmed humeral components in aTSA exhibit comparable revision rates and survival probabilities. Rotator cuff insufficiency and polyethylene wear are the two most common complications leading to revision. To facilitate ongoing monitoring and optimize patient safety, we implemented a modification in the follow-up protocol, transitioning to annual appointments or earlier when necessary. This study underscores the unsolved disadvantages in metal-back components and the importance of a mid- to long-term longitudinal assessment of those patients.

Scapulothoracic orientation has a significant influence on the clinical outcome after reverse total shoulder arthroplasty.

BACKGROUND: Computer simulation has indicated a significant effect of scapulothoracic orientation and posture on range of motion (ROM) after reverse total shoulder arthroplasty (RTSA). We analyzed this putative effect on the clinical and radiologic outcome post-RTSA. METHODS: We retrospectively assessed 2-year follow-up data of RTSA patients treated at our clinic between 2008 and 2019. Patients were categorized into posture types A, B, and C based on an established method using scapular internal rotation on preoperative cross-sectional imaging. We compared differences in clinical ROM, pain, Subjective Shoulder Value, Constant Score, Shoulder Pain and Disability Index (SPADI), quality of life (EuroQol-5 Dimensions-5 Level utility index), and radiologic outcomes between posture types using linear regression analyses. RESULTS: Of 681 included patients, 225 had type A posture, 326 type B, and 130 type C. Baseline group characteristics were comparable, although the type C group had a higher proportion of females (60% [A], 64% [B], 80% [C]) with lower abduction strength (0.7 kg [A], 0.6 kg [B], 0.3 kg [C]) and a slightly higher proportion with a Grammont design RTSA (41% [A], 48% [B], 54% [C]). There were significant adjusted differences in mean (±standard deviation) active flexion (A: 137° ± 21°; B: 136° ± 20°; C: 131° ± 19°) and passive flexion (A: 140° ± 19°; B: 138° ± 19°; C: 134° ± 18°), active (A: 127° ± 26°; B: 125° ± 26°; C: 117° ± 27°) and passive abduction (A: 129° ± 24°; B: 128° ± 25°; C: 121° ± 25°), SPADI (A: 81 ± 18; B: 79 ± 20; C: 73 ± 23), and pain (A: 1.2 ± 1.7; B: 1.6 ± 2.2; C: 1.8 ± 2.4) between posture types at 2 years (P ≤ .035). A higher distalization shoulder angle was associated with better abduction in type C patients (P = .016). Type C patients showed a trend toward a higher complication rate (3.9% vs. 1.1% [A], 3.2% [B]) (P = .067). CONCLUSIONS: Type C posture influences the 2-year clinical outcome of RTSA patients in terms of worse flexion, abduction, SPADI, and pain. Scapulothoracic orientation and posture should be considered during the patient selection process, preoperative planning, and implantation of an RTSA.