Varus failure is a well-known complication of open reduction internal fixation of proximal humeral fractures. The addition of tension-reducing sutures from the plate to the rotator cuff may attenuate the deforming forces of the rotator cuff resulting in decreased varus failure. In this study, we investigate the biomechanical contributions of tension-reducing sutures to a locked plate construct in a 2-part proximal humerus fracture model.
Two fixation techniques were tested in 12 matched fresh frozen humeri in which standard 2-part fractures of the surgical neck were created with a gap simulating surgical neck medial comminution. In group 1, fractures were fixed with a standard proximal humerus locking plate. In group 2, the plate fixation was similar, and additionally, tension-reducing sutures were applied from the plate to the rotator cuff. Active abduction was simulated for 400 cycles with force applied through the rotator cuff tendons. Intercyclic fracture motion, change in displacement, and load to failure were recorded.
The addition of tension-reducing sutures did not lead to significant differences in intercyclic fracture motion. The mean change in displacement and load to failure were similar in both groups. Failure typically occurred in both groups at the rotator cuff testing clamp interface.
Tension-relieving rotator cuff sutures added to locking plate fixation did not lead to a change in fracture gap with cyclic loading or an increase in ultimate failure load in a 2-part surgical neck proximal humerus fracture model without medial support.
*Department of Orthopaedic Surgery, Saint Louis University School of Medicine, St Louis, MO;
†Saint Louis University School of Medicine, St Louis, MO; and
‡Saint Louis University Parks School of Engineering, St Louis, MO.
Reprints: Scott G. Kaar, MD, Department of Orthopaedic Surgery, Saint Louis University, 3635 Vista at Grand Boulevard, St Louis, MO 63110 (e-mail: firstname.lastname@example.org).
Presented at the Mid-America Orthopaedic Association Meeting, 2013, Amelia Island, FL.
Supported in part from an Orthopedic Research and Educational Foundation resident research grant. Synthes donated the plates and screws. Arthrex donated the sutures.
The authors report no conflict of interest.
Accepted December 10, 2013