Biomechanical evaluation of volar locking plates for distal radius fractures.
OBJECTIVE
Fixed-angle devices have been a major advancement in orthopedic fracture care and have become an attractive option for fixation of distal radius fractures. Several volar locking plates exist, but there is insufficient literature comparing the strengths of these plates. This study compares the biomechanical strength of two popular volar locking plate systems (Synthes LCP and Hand Innovations DVR-A) along with a nonlocking volar T-plate (Synthes).


METHODS
Twenty-three formalin-fixed cadaveric forearms were divided into three groups with similar ages and bone densities. An unstable extra-articular fracture was created using a standardized osteotomy. Each group was fixed with one of the three plates. Each specimen was loaded in axial compression for 2000 cycles at a force of 400 N. Each specimen that completed cyclic testing was loaded to failure. Stiffness, yield point, and ultimate strength were recorded for each construct.


RESULTS
Each fixed-angle construct completed all 2000 cycles. The nonlocking plates failed at an average of 560 cycles. The mean stiffness of the DVR-A, LCP, and the volar T-plates were 277.00, 343.17, and 175.67 N/mm, respectively. There was a statistically significant difference between both fixed-angle plates and the nonlocking plate (p < 0.05). The difference between each fixed-angle construct did not reach significance. Yield point and ultimate strength could only be determined for the two fixed-angle devices. There was no statistically significant difference between the constructs for both yield point (DVR-A = 855.56 N, LCP = 894.15 N) and ultimate strength (DVR-A = 1,021.97 N, LCP = 1,114.87 N).


CONCLUSIONS
Given our data, fixed-angle constructs withstand cyclical loading representing normal physiologic forces encountered during post-operative rehabilitation. There was no significant biomechanical difference between the two fixed-angle constructs. Our results support that volar fixed-angle locking plates are an effective treatment for unstable extra-articular distal radius fractures, allowing early postoperative rehabilitation to safely be initiated.
Levin
Scott M
SM
Department of Orthopaedic Surgery, T-18 Health Sciences Center, SUNY at Stony Brook University Hospital, Stony Brook, NY, 11794-8181, USA.
Nelson
Cory O
CO
Botts
Jonathan D
JD
Teplitz
Glenn A
GA
Kwon
Yong
Y
Serra-Hsu
Fred
F
J Hand Surg Am. 2003 Jan;28(1):94-104
12563644
J Hand Surg Am. 1997 Sep;22(5):777-84
9330133
J Bone Joint Surg Br. 1996 Jul;78(4):588-92
8682826
J Hand Surg Am. 2006 May-Jun;31(5):771-9
16713841
Acta Orthop Scand. 1989 Aug;60(4):465-7
2816326
J Am Acad Orthop Surg. 2005 Jan-Feb;13(1):28-36
15712980
Bone. 1995 Nov;17(5 Suppl):505S-511S
8573428
J Hand Surg Am. 2005 Jul;30(4):756-63
16039369
J Hand Surg Am. 2000 May;25(3):469-75
10811751
J Hand Surg Am. 1994 Mar;19(2):325-40
8201203
J Am Acad Orthop Surg. 2005 May-Jun;13(3):159-71
15938605
Injury. 2003 Jul;34(7):497-502
12832175
J Orthop Trauma. 2004 Sep;18(8):488-93
15475843
J Hand Surg Am. 1998 Mar;23(2):300-7
9556273
J Hand Surg Am. 2004 May;29(3):446-51
15140488