Review Question - QID 210122

Displaced clavicle fractures are associated with higher rates of nonunion.

Nonunion occurs in roughly 5-6% of clavicle fractures and can result in slower functional return, poor cosmesis and muscle fatigability. Clavicle fractures can be sub-classified using the Allman classification into medial, diaphyseal, and lateral injuries (Illustration A). The Neer classification for diaphyseal injuries describes fractures as "nondisplaced" (less than 100% displacement) and "displaced" (greater than 100% displacement).

Robinson et al. performed a prospective cohort study to identify risk factors for nonunion after nonoperative management of clavicle fractures. The overall nonunion rate was 6.2% and was highest in lateral third fractures (11.5%). Diaphyseal fractures had the lowest nonunion rate (4.5%). Additionally, the authors found that the risk for nonunion was increased by advancing age, female gender, fracture displacement, and comminution.

Jorgensen et al. performed a systemic review of the literature looking for predictors of non-union and malunion in mid shaft clavicle fractures treated non-operatively. They found fracture comminution, displacement, older age, female gender, and the presence of smoking to be his factors for non-union. Of these, displacement was the most likely factor that can be used to predict non-union.

Figure A demonstrates a displaced left clavicle diaphyseal fracture. Note that the medial fragment is displaced superiorly by the deforming force of the sternocleidomastoid. Illustration A represents the Allman classification. Illustration B demonstrates the deforming forces acting on the clavicle.

Incorrect Answers:
Answer 1: Diaphyseal fractures were demonstrated to have the lowest rate of nonunion when compared to lateral third fractures and medial clavicle fractures.
Answer 3: Advancing age was found to be an independent predictor of nonunion.
Answer 4: Female gender was found to be an independent predictor of nonunion.
Answer 5: Injury to the dominant hand was not found to be associated with an increased risk of non-union.