Specific scapular kinematic patterns to differentiate two forms of dynamic scapular winging.

Area of Science:

• Orthopedics
• Neurology
• Biomechanics

Background:

• Dynamic scapular winging (DSW) is a rare condition causing significant disability due to impaired scapular stability and motion.
• Common causes include long thoracic nerve lesions (LTNL) affecting the serratus anterior and spinal accessory nerve lesions (SANL) affecting the trapezius.
• Understanding the specific kinematic patterns associated with each lesion is crucial for diagnosis and management.

Purpose of the Study:

• To analyze and differentiate the 3D scapular kinematic patterns in patients with DSW caused by LTNL versus SANL.
• To correlate specific kinematic findings with the type of neurological lesion.

Main Methods:

• A non-invasive electromagnetic device was used to assess 3D scapular kinematics during arm elevation in the frontal and sagittal planes.
• Nine patients with unilateral DSW (5 LTNL, 4 SANL), confirmed by electrical evidence, were included.
• Differences between affected and unaffected shoulders were analyzed and compared between the LTNL and SANL groups.

Main Results:

• Patients with LTNL showed significantly greater differences in scapular posterior tilt compared to those with SANL.
• Patients with SANL exhibited significantly greater differences in scapular protraction and lateral rotation compared to those with LTNL.
• These kinematic differences were observed at various degrees of arm elevation in both frontal and sagittal planes.

Conclusions:

• The study identified distinct 3D scapular kinematic patterns specific to LTNL and SANL.
• These kinematic findings correlate with known clinical signs and the functional roles of the affected muscles.
• The results aid in differentiating DSW etiologies and inform targeted treatment strategies.