526 - A case of chronic scapulothoracic pain from an undiagnosed posterior 5th rib nonunion fracture

Case Diagnosis: Scapulothoracic pain from a posterior rib fracture.

Case Description: A 52-year-old female with multilevel cervicothoracic spondylosis and bilateral C4-C6 foraminal stenosis presented with chronic left scapulothoracic pain radiating to the left axilla, arm, and chest exacerbated by left cervical rotation, left scapular protraction, and overhead activities. She completed physical therapy addressing her cervical spine without relief and was recommended for cervical fusion surgery. Examination revealed restricted left cervical rotation, diffusely diminished light touch sensation in the left arm, and positive Roos test bilaterally. Left upper extremity had full strength and shoulder exam was unremarkable. Magnetic resonance angiogram (MRA) was ordered to evaluate for thoracic outlet syndrome, which demonstrated mild symmetric narrowing of the bilateral subclavian arteries in the scalene triangle in the arms up position, and an incidental finding of posterior 5th rib nonunion fracture in proximity to the subscapularis and anterior scapular surface, edema in the scapulothoracic articulation and 6th costovertebral joint, and left-sided 6mm pneumothorax.

Discussions: This patient presented to a Physical Medicine and Rehabilitation Sports Medicine clinic for an additional opinion before undergoing a cervical spinal fusion. Examination was inconsistent with cervical radiculopathy, prompting further evaluation for thoracic outlet syndrome given the diffuse, nondermatomal pattern and provocation with overhead activity. Imaging revealed an incidental left posterior 5th rib fracture with nonunion, likely resulting in friction at the scapulothoracic articulation and abnormal rib motion. She reported recent and remote motor vehicle accidents possibly contributing. Radiology and pulmonology determined that MRA findings of possible thoracic outlet syndrome had unclear clinical significance and the pneumothorax was likely due to vaping. The patient was referred to physical therapy for scapular mobilization and orthopedics for consideration of scapulothoracic decompression.

Conclusions: This case illustrates multiple potential causes of scapulothoracic pain and describes an atypical etiology, emphasizing the importance of physical examination and appropriate imaging.