Functional Outcomes After Reverse Total Shoulder Arthroplasty: Comparing Grammont and Lateralized Prosthesis Designs

Area of Science:

• Orthopedic surgery
• Biomedical engineering
• Reconstructive surgery

Background:

• Reverse total shoulder arthroplasty (RTSA) is a key treatment for complex proximal humerus fractures, especially in older adults.
• Medialized (Grammont-type) and lateralized prostheses are two designs used in RTSA.
• Implant design may impact patient outcomes, including range of motion and complications.

Purpose of the Study:

• To compare rotational mobility, functional outcomes, and complication rates between medialized and lateralized RTSA designs.
• The study focused on patients treated for proximal humerus fractures and related conditions.

Main Methods:

• A retrospective comparative study (Level III evidence) included 27 patients treated with RTSA between 2007 and 2023.
• Patients were grouped by prosthesis design: medialized (n=13) versus lateralized (n=14).
• Functional outcomes were assessed using SANE, DASH, Constant-Murley, SST, ADLEIR, and EQ-5D scores; range of motion was also measured.

Main Results:

• No statistically significant differences were found in external rotation (15° vs 20.7°), internal rotation, or other range-of-motion parameters between the groups.
• Functional outcome scores (SANE, DASH, Constant-Murley, SST, ADLEIR, EQ-5D) were similar across both prosthesis designs.
• Complication rates were 23.1% for medialized and 7.1% for lateralized RTSA, but this difference was not statistically significant (OR 3.9, p=0.23).

Conclusions:

• Current evidence suggests no significant differences between medialized and lateralized RTSA designs regarding rotational mobility, functional outcomes, or complication rates.
• The study's small sample size may limit its power to detect clinically relevant differences.
• Further prospective research with larger cohorts is recommended to definitively assess the comparative effectiveness of different RTSA implant designs.