Lu Bai1, Zhongguo Fu, Shuai An, Peixun Zhang, Dianying Zhang, Baoguo Jiang. 1. *Department of Sports Medicine, Shenzhen Hospital, Peking University, Shenzhen, China; and †Department of Orthopedics and Traumatology, Peoples' Hospital, Traffic Medicine Center, Peking University, Beijing, China.
Abstract
OBJECTIVES: To evaluate the effect of calcar screw use in proximal humeral fractures with unstable medial support treated with locked plates. METHODS: Standard osteotomies were performed in 36 cadaveric humeri to create a surgical neck fracture proximal humeral model. For static testing, 12 pairs of humeri were divided into 4 groups: normal alignment and varus deformity groups with and without 5-mm medial deficiencies. Calcar screw function was measured in each group by axial, shear, and torsion stiffness tests. Another 6 pairs of humeri with 5-mm medial deficiencies were subjected to cyclic loading tests in the normal alignment model with and without calcar screw application. RESULTS: Calcar screws improved rotational stability in the normal alignment (P = 0.007) and varus (P = 0.002) groups. Calcar screws improved static and cyclic axial (P = 0.004) and shear (P = 0.017) stability in the normal alignment group with medial deficiency. In specimens with normal alignment and intact medial cortex, calcar screws provided no advantage in axial (P = 0.535) or shear (P = 0.537) stiffness. Calcar screws did not provide sufficient axial (P = 0.782) or shear (P = 0.772) stability to avoid reduction loss in humeri with varus malreduction. CONCLUSIONS: In humeri with normal alignment, calcar screws can provide additional stability even when a medial deficiency exists. The use of calcar screws in humeri with varus deformity showed no biomechanical superiority.
OBJECTIVES: To evaluate the effect of calcar screw use in proximal humeral fractures with unstable medial support treated with locked plates. METHODS: Standard osteotomies were performed in 36 cadaveric humeri to create a surgical neck fracture proximal humeral model. For static testing, 12 pairs of humeri were divided into 4 groups: normal alignment and varus deformity groups with and without 5-mm medial deficiencies. Calcar screw function was measured in each group by axial, shear, and torsion stiffness tests. Another 6 pairs of humeri with 5-mm medial deficiencies were subjected to cyclic loading tests in the normal alignment model with and without calcar screw application. RESULTS: Calcar screws improved rotational stability in the normal alignment (P = 0.007) and varus (P = 0.002) groups. Calcar screws improved static and cyclic axial (P = 0.004) and shear (P = 0.017) stability in the normal alignment group with medial deficiency. In specimens with normal alignment and intact medial cortex, calcar screws provided no advantage in axial (P = 0.535) or shear (P = 0.537) stiffness. Calcar screws did not provide sufficient axial (P = 0.782) or shear (P = 0.772) stability to avoid reduction loss in humeri with varus malreduction. CONCLUSIONS: In humeri with normal alignment, calcar screws can provide additional stability even when a medial deficiency exists. The use of calcar screws in humeri with varus deformity showed no biomechanical superiority.
Authors: Kyong S Min; Bethany Sheridan; Greg R Waryasz; Alexander Joeris; Jon J P Warner; David Ring; Neal Chen Journal: Eur J Orthop Surg Traumatol Date: 2021-01-04
Authors: Sjur Oppebøen; Annette K B Wikerøy; Hendrik F S Fuglesang; Filip C Dolatowski; Per-Henrik Randsborg Journal: J Orthop Surg Res Date: 2018-08-09 Impact factor: 2.359
Authors: Jan Theopold; Stefan Schleifenbaum; Mirijam Müller; Michael Werner; Niels Hammer; Christoph Josten; Pierre Hepp Journal: PLoS One Date: 2018-10-29 Impact factor: 3.240