gms | German Medical Science

Objectives: It is assumed, that dorsocranial displacement of the greater tuberosity in humeral head fractures is caused by rotator cuff traction. The purpose of this study was to investigate the association between rotator cuff status and displacement characteristics of the greater tuberosity in 4-part humeral head fractures.

Methods: Computed tomography scans of 121 patients with Neer type 4 fractures were analyzed. Fatty infiltration of the supra- and infraspinatus muscles was classified according to Goutallier. In all fractures the Head-Shaft Angle (HSA) was determined to distinguish varus-displaced (HSA< 125°) from non-varus displaced fractures (HSA >125°). Position determination of the greater tuberosity fragment was performed in both, coronary and axial planes to assess the extent of dorsocranial displacement.

Results and Conclusion: Considering non-varus displaced fractures, the extend of dorsocranial displacement was significant higher in patients with mostly inconspicuous posterosuperior rotator cuff status compared to advanced fatty degenerated cuffs. In varus displaced humeral head fractures no correlation between displacement of the greater tuberosity and the condition of the posterosuperior rotator cuff could be detected.

Greater tuberosity displacement in humeral head fractures by rotator cuff traction cannot be applied to all fracture types.

In non-varus 4-part humeral head fractures cranial and dorsal displacement of the greater tuberosity depends on the status of the posterosuperior rotator cuff.

Varus impacted fractures interpretated as an impression injury caused by the acromion is more likely than fracture displacement due to rotator cuff traction.