Bilateral Congenitally Absent Trapezius Musculature and Anomalous Scapuloclavicular Accessory Muscle: A Case Report

Area of Science:

• Orthopedics
• Human Anatomy
• Congenital Anomalies

Background:

• Lateral scapular winging can cause severe shoulder dysfunction.
• The trapezius muscle plays a crucial role in scapular stability and shoulder movement.

Purpose of the Study:

• To report a unique case of bilateral absent trapezius muscles in a pediatric patient.
• To describe the surgical management and outcomes for severe shoulder dysfunction caused by this anomaly.
• To document a previously unidentified anomalous muscle found during surgery.

Main Methods:

• A 10-year-old boy with bilateral shoulder dysfunction due to lateral scapular winging was evaluated.
• The patient underwent bilateral modified Eden-Lange tendon transfers to address the muscle deficit.
• Intraoperative findings included bilateral absent trapezius muscles and an anomalous scapuloclavicular muscle.

Main Results:

• The modified Eden-Lange tendon transfers resulted in near-normal restoration of shoulder range of motion at the 1-year follow-up.
• Intraoperative examination revealed bilateral absence of the trapezius muscles.
• A novel anomalous muscle connecting the scapula to the clavicle was identified.

Conclusions:

• This is the only reported case of bilateral absent trapezius muscles without other associated trunk or congenital abnormalities.
• The successful surgical intervention demonstrates a viable treatment option for this rare condition.
• The discovery of an anomalous scapuloclavicular muscle adds to the understanding of human anatomical variations.