Biomechanical Analysis of the Efficacy of Locking Plates during Cyclic Loading in Metacarpal Fractures

Abstract

Purpose. To analyse the biomechanical characteristics of locking plates under cyclic loading compared to a nonlocking plate in a diaphyseal metacarpal fracture. Methods. Oblique diaphyseal shaft fractures in porcine metacarpal bones were created in a biomechanical fracture model. An anatomical reduction and stabilization with a nonlocking and a comparable locking plate in mono- or bicortical screw fixation followed. Under cyclic loading, the displacement, and in subsequent load-to-failure tests, the maximum load and stiffness were measured. Results. For the monocortical screw fixation of the locking plate, a similar displacement, maximum load, and stiffness could be demonstrated compared to the bicortical screw fixation of the nonlocking plate. Conclusions. Locking plates in monocortical configuration may function as a useful alternative to the currently common treatment with bicortical fixations. Thereby, irritation of the flexor tendons would be avoided without compromising the stability, thus enabling the necessary early functional rehabilitation.

New fixation approach for transverse metacarpal neck fracture: a biomechanical study

“…However, no existent in vitro biomechanical test is able to reflect actual amounts of physiological loading. In addition to the cantilever bending test, previous studies have adopted tests including the three-point bending test [ 17 ], modified three-point bending test [ 13 , 21 , 22 ], four-point bending test [ 16 , 18 ], and torsional test [ 12 , 23 ]. We employed the cantilever bending test instead of a bending test mainly because the aim of the study was to explore fixation approaches for metacarpal neck fracture not metacarpal shaft fracture.…”

“…We employed the cantilever bending test instead of a bending test mainly because the aim of the study was to explore fixation approaches for metacarpal neck fracture not metacarpal shaft fracture. Previously, the maximum fracture force and stiffness were common indexes for scholars to determine fixation strength [ 12 , 14 , 16 , 17 , 21 , 23 ]. In this study, however, the strength was assessed by evaluating the stiffness alone.…”

“…The results indicated that when monocortical bone fixation was employed, the stiffness of the fixation using a locking plate (83 + 35 N/mm) was higher than that using a regular plate (46 + 12 N/mm). Doht et al [ 21 ] also conducted modified three-point bending tests on pig metacarpal bones. Despite the mean stiffness of the locking plate group exceeding that of the regular plate group, the difference was nonsignificant.…”

Comparing biomechanical strength of unicortical locking plate versus bicortical compression plate for transverse midshaft metacarpal fracture

“…20 Doht et al conducted a biomechanical test comparing non-locking and locking plates in mono-or bicortical screw fixation of the metacarpal fracture model by cyclic loading for 1000 cycles using only 20% of the maximum load of the original bone, with a value ranging from 101 to 119 N, followed by observation of differential displacement of the construct. 21 There was no significant difference between the monocortical screw fixation of the locking plate and bicortical screw fixation of the non-locking plate. It was demonstrated that both have similar displacement, maximum load to failure, and stiffness.…”

Biomechanical Comparison of 2 Veterinary Locking Plates to Monocortical Screw/Polymethylmethacrylate Fixation in Canine Cadaveric Cervical Vertebral Column

“…Monocortical screw/PMMA constructs have not been found biomechanically different to bicortical pin/PMMA constructs . Due to the increased strength and rigidity of the screw‐plate interface, monocortical instead of bicortical screw fixation is acceptable for locking screw/plate constructs . This makes their use for the canine cervical vertebral column ideal, making implantation easier and less risk of complications related to local tissue and neurovascular damage.…”