Clinical benefits of the reconstruction of the normal humeral neck-shaft angle for displaced proximal humerus fractures treated with locking plates

Abstract

Objective To investigate the normal humeral neck-shaft angle (NSA) and the clinical benefits of reconstructing normal NSA for displaced proximal humerus fractures treated with locking plates.Methods Humeral NSA was measured in 382 normal adults.A retrospective analysis was conducted on 128 patients with proximal humerus fractures treated with locking plates from June 2006 to February 2011.The postoperative NSA of the affected shoulders was measured,and all cases were divided into 3 groups based on bilateral 95％ reference range of the normal NSA: varus group in which the postoperative NSA was smaller than the lower limit of the bilateral 95％ reference range,normal group in which the postoperative NSA was within the bilateral 95％ reference range,and valgus group in which the postoperative NSA was larger than the upper limit of the bilateral 95％ reference range.The changes of the NSA,Constant shoulder scores,visual analog scale (VAS) score and complications were documented for analysis.Results The mean normal NSA was 136.1°± 4.5 °and the bilateral 95％ reference range was 127.2 ° to 144.9 °.All patients were followed up for 6 to 32 months.There were 29 patients in varus group,90 in normal group and 9 in valgus group.For the 3 groups,at final follow-up,the mean Constant shoulder score was 70.3,77.2 and 73.2,respectively; the mean VAS score was 2.8,1.8 and 2.1,respectively; the mean varus angle was 4.2°,1.6° and 3.1°,respectively; and the incidence of complications was 34.5％,14.4％ and 22.2％,respectively.The results of the normal group were better than those of varus group in terms of Constant shoulder score,VAS score,and incidence of complications.Conclusion Reconstruction of the normal NSA is crucial to the good clinical outcomes.Patients with initial varus malreduction have a higher incidence of complications,such as secondary loss of reduction. Key words: Humeral fractures; Fracture fixation, internal; Treatment failure