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

Abstract

Objective: 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.

Method: 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.

Results: 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.

Conclusion: 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.