Avulsion fractures of the scapula

Abstract

Fractures of the scapula due to direct violence are relatively common. Wilber and Evans [18] reported 40 scapular fractures and reviewed the literature. All those injured had received direct trauma to the shoulder and they were able to divide their cases into two groups, based on anatomical location and functional results. Scapular fractures due to avulsion of the muscular attachments are uncommon and, as reports of these injuries in the literature are usually confined to single cases, no classification has been established which takes account of the anatomical sites at which these fractures occur and the mechanism of injury involved. In this paper the more common sites of avulsion injury of the scapula are described and illustrated by case reports. In several of these the skeletal injury resulted from muscle contraction against a resisted force on the upper limb during the course of an accident. This mechanism has been implicated in fractures of the coracoid and acromion, but is shown in this paper to contribute to other avulsion fractures.

Bony avulsion of the supraspinatus origin from the scapular spine

“…Four studies have attempted to identify or to discuss the mechanism of avulsions [3–5, 12]. Heyse-Moore et al [3] were not able to describe a specific mechanism for avulsions of the superior border of the scapula.…”

“…Heyse-Moore et al [3] were not able to describe a specific mechanism for avulsions of the superior border of the scapula. However, their 7 cases did not involve a scapular spine avulsion.…”

The Shoulder: Acquired Disorders

“…Winging of the scapula-most often a result of injury to the long thoracic nerve-can result from avulsion fracture at the insertion of the serratus anterior muscle along the inferior angle of the scapula [ 48 ]. Additional sites for scapular avulsion fracture include the infraglenoid tubercle (the attachment site for the triceps muscle), acromion (the deltoid muscle), coracoid (the coracoclavicular ligament), and coracoid tip (the short head biceps and coracobrachialis muscles), among others.…”

Incomplete Avulsion Fractures of the Scapular Spine Caused by Violent Muscle Contraction

“…4 In contrast, avulsion fractures caused by voluntary muscle contraction arise from resisted muscle pull as a result of trauma or unusual exertion. 2 Reported scapular fracture sites and the possible causative muscles are diverse. 2,[5][6][7][8] The coracoid, acromion, and scapular spine, which are generally referred to as scapular processes, are particularly prone to avulsion fractures because of their anatomical and structural characteristics.…”

“…2 Reported scapular fracture sites and the possible causative muscles are diverse. 2,[5][6][7][8] The coracoid, acromion, and scapular spine, which are generally referred to as scapular processes, are particularly prone to avulsion fractures because of their anatomical and structural characteristics. Fractures of the coracoid possibly occur as a result of traction of the conjoint tendon along with or without the pectoralis minor.…”