The clinical benefit of medial support screws in locking plating of proximal humerus fractures: a prospective randomized study

The purpose of this study was to evaluate the clinical benefit of medial support screws for locking plating of proximal humerus fractures.

Seventy-two consecutive patients underwent prospective treatment for proximal humerus fractures with locking plates between October 2007 and September 2008. Sixty-eight patients accomplished a mean 30.8-month follow-up and were randomized into two groups: 39 patients were treated with only a locking plate and were classified in the –MSS (medial support screw) group, and 29 patients were included in the + MSS group, which were fixed with additional medial support screws. Clinical and radiological investigations were performed in both groups.

The fractures united at an average of 13.6 weeks after final surgery. Comparably better shoulder function recovery was achieved in the +MSS group with regard to the Constant shoulder score (P = 0.01), with the respective excellent and good rates of 79% and 62%. Eleven patients developed various complications. A statistical difference (P = 0.036) was observed regarding the failure rate (23.1% in the −MSS group vs. 3.4% in the +MSS group). The early loss of fixation was related to higher age (P < 0.001) and less initial neck-shaft angle (NSA) (P = 0.011) of the patients. However, bone mineral density was not significantly associated with loss of fixation (P = 0.076). Although no difference was found in all types of the fractures between the +MSS and −MSS groups regarding immediate postoperative NSA, we observed a significantly lower final NSA in the −MSS group and greater secondary angle loss in the subgroup of Neer three-part (P = 0.033 and 0.015, respectively) and four-part fractures (P = 0.043 and 0.027).

Anatomical reduction can substantially decrease the risk of postoperative failure in locking plating of proximal humerus fractures. Medial support for proximal humerus fractures seems to have no benefits in Neer two-part fractures. However, the additional medial support screws inserted into the medio-inferior region of the humeral head may help to enhance mechanical stability in complex fractures and allow for better maintenance of reduction.