Biomechanical Comparison of Fixed- versus Variable-Angle Locking Screws for Distal Humerus Comminuted Fractures
10.4055/cios.2019.11.3.302
- Author:
Ali NOURBAKHSH
1
;
Adam G HIRSCHFELD
;
Sravan DHULIPALA
;
William HUTTON
;
Timothy GANEY
;
Luis LOZADA
;
Daniel SCHLATTERER
;
Gary Mark LOURIE
Author Information
1. Department of Orthopedics, WellStar Atlanta Medical Center, Atlanta, GA, USA.
- Publication Type:Original Article
- Keywords:
Humerus;
Fracture fixation;
Bone screws
- MeSH:
Bone Screws;
Cadaver;
Fracture Fixation;
Fractures, Comminuted;
Humerus;
Olecranon Process;
Stainless Steel
- From:Clinics in Orthopedic Surgery
2019;11(3):302-308
- CountryRepublic of Korea
- Language:English
-
Abstract:
BACKGROUND: To compare the stability of fixed- versus variable-angle locking constructs for the comminuted distal humerus fracture (AO/OTA 13-A3). METHODS: Eight pairs of complete humeri harvested from eight fresh frozen cadavers were used for the study. We fixed the intact humeri using 2.7-mm/3.5-mm locking VA-LCP stainless steel distal humerus posterolateral (nine-hole) and medial (seven-hole) plates. An oscillating saw was used to cut a 1-cm gap above the olecranon fossa. The specimens were loaded in axial mode with the rate of 1 mm per 10 seconds to failure, and stress-strain curves were compared in each pair. The mode of failure was recorded as well as the load needed for 2- and 4-mm displacement at the lateral end of the gap. RESULTS: The stiffness of the constructs, based on the slope of the stress-strain curve, did not show any difference between the fixed- versus variable-angle constructs. Likewise, there was no difference between the force needed for 2- or 4-mm displacement at the lateral gap between the fixed- and variable-angle constructs. The mode of failure was bending of both plates in all specimens and screw pull-out in four specimen pairs in addition to the plate bending. CONCLUSIONS: Our results did not show any difference in the biomechanical stability of the fixed- versus variable-angle constructs. There was not any screw breakage or failure of the plate-screw interface.
