Malunion of the clavicle causes significant glenoid malposition: a quantitative anatomic investigation

An experimental cadaver model was used to assess the effects of a malunited fracture of the middle third of the clavicle on the functional anatomy of the shoulder joint.

Anatomic samples were prepared with simulated shortening and axial malposition of the clavicle. From these, alterations in glenoid fossa position were measured and depicted graphically.

Healing of clavicle fractures with bony shortening leads to a ventromedialcaudal shift in glenoid fossa position. The following malpositions of the clavicle lead to the respective glenoid fossa positional changes: caudal deviation leads to a mediocaudal shift, cranial deviation leads to a dorsolateral shift of the glenoid fossa, ventral deviation causes a ventrolateral shift, dorsal deviation leads to mediocaudal shift of the fossa, cranial rotation leads to ventrolateral shift in fossa position, and caudal rotation leads to a dorsomedial shift in glenoid fossa position.

Clinical implication of these data is that bony shortening in combination with caudal displacement leads to distinct functional deficits in abduction, particularly overhead motion. Using the above data, a vector model was created to calculate position of the glenoid fossa dependent on clavicle position/malposition. The model is a valuable tool to be used for planning open reduction and fixation of clavicular fractures or malunions.