Subscapularis integrity, function and EMG/nerve conduction study findings following reverse total shoulder...

Area of Science:

• Orthopedic surgery
• Musculoskeletal imaging
• Neuromuscular diagnostics

Background:

• The functional status of the subscapularis muscle after reverse total shoulder arthroplasty (RTSA) is not well understood.
• Assessing subscapularis integrity and nerve function post-RTSA is crucial for patient outcomes.

Purpose of the Study:

• To evaluate the integrity and function of the repaired subscapularis tendon and muscle after RTSA.
• To assess subscapularis muscle and lower subscapular nerve function using ultrasound, electromyography (EMG), and nerve conduction studies (NCS).

Main Methods:

• Included 20 patients with minimum 6-month follow-up after RTSA and subscapularis repair.
• Performed ultrasound, EMG, and NCS on the subscapularis, comparing with contralateral shoulders.
• Correlated imaging and electrodiagnostic findings with patient-reported functional outcomes.

Main Results:

• Ultrasound revealed abnormal but intact subscapularis tendons in 4 patients.
• Lower subscapular nerve conduction studies (NCS) showed abnormalities in 9 patients compared to the contralateral side.
• All patients exhibited normal subscapularis EMG results, with no significant correlation between diagnostic findings and functional outcomes.

Conclusions:

• The subscapularis muscle demonstrates neurological functionality post-RTSA, as indicated by EMG and NCS.
• Identified lower subscapular nerve conduction abnormalities in 45% of patients did not impact functional outcomes.