[Biomechanical research of antegrade intramedullary fixation for the metacarpal fractures].
OBJECTIVE
To study the biomechanical characteristics of antegrade intramedullary fixation for metacarpal fractures.


METHODS
From March to May 2008, both the 4th and 5th metacarpals from 25 formalin embalmed cadaver hands had three-point bending test after transverse osteotomy followed by randomly fixation with one of the following three methods: plate and screw, antegrade intramedullary K-wire, crossed K-wire. While, both the 2nd and 3rd metacarpals had torsional loading test after the same management as the 4th and 5th metacarpal had undergone.


RESULTS
In the three-point bending test, both the maximum bending moment (M(max)) and bending rigidity (EI) of the antegrade intramedullary K-wire were comparable with those of the plate and screw, and were significantly larger than those of the crossed K-wire. In the torsional loading test, the antegrade intramedullary K-wire had a statistically smaller maximum torque (T(max)) than the plate and screw, and had a comparable T(max) with the crossed K-wire; while, the torsional rigidity (GJ) of the intramedullary K-wire was statistically weaker than that of both the plate and screw and the crossed wire.


CONCLUSIONS
One single antegrade intramedullary K-wire can provide a satisfactory M(max) and EI for metacarpal fixation and shows relatively weak in the torsional loading test. The injured finger should be well protected to avoid torsional deformity in clinical practice.
Zhang
Li-shan
LS
Department of Hand Surgery, Beijing Jishuitan Hospital, Beijing, China.
Pan
Yong-wei
YW
Tian
Guang-lei
GL
Li
Wen-jun
WJ
Xia
Shao-hua
SH
Tao
Jian-feng
JF
D000328:Adult; D001696:Biomechanical Phenomena; D001860:Bone Plates; D001863:Bone Screws; D001864:Bone Wires; D002102:Cadaver; D005593:Fracture Fixation, Internal / Q000295:instrumentation / Q000379:methods*; D050723:Fractures, Bone / Q000601:surgery*; D006801:Humans; D050279:Metacarpal Bones / Q000293:injuries*; D010027:Osteotomy