Involvement of the scapulothoracic articulation after well-functioning reverse total shoulder arthroplasty

Area of Science:

• Orthopedic Surgery
• Biomechanics
• Rehabilitation Science

Background:

• Shoulder movement involves glenohumeral (GH) and scapulothoracic (ST) joint coordination, known as the scapulohumeral rhythm (SHR).
• Reverse total shoulder arthroplasty (rTSA) is known to modify scapulothoracic kinematics and SHR.
• Previous research indicates altered SHR post-rTSA, necessitating further kinematic analysis.

Purpose of the Study:

• To analyze scapulothoracic motion after rTSA.
• To compare scapulothoracic kinematics and SHR in rTSA patients versus healthy individuals.
• To identify kinematic differences that may inform rehabilitation and surgical planning.

Main Methods:

• Retrospective analysis of 13 rTSA patients and 25 healthy controls.
• Scapular kinematic assessment using miniature inertial measurement units.
• Clinical and functional outcome measures including range of motion and validated scores.

Main Results:

• rTSA patients exhibited significantly increased scapular upward rotation and retraction compared to healthy controls.
• No significant difference in scapular tilt was observed between groups.
• The SHR was notably different, with rTSA patients showing a greater ST joint contribution throughout abduction compared to healthy controls.

Conclusions:

• Scapulothoracic joint kinematics are significantly altered after rTSA.
• Overhead motion in rTSA patients involves increased scapular rotation and retraction.
• Understanding these altered ST kinematics is crucial for optimizing rTSA rehabilitation and preoperative planning.