The use of interlocking intramedullary nail is accepted one of treatment choices in the comminuted fractures of humeral shaft. The insertion of distal interlocking screws remains technically problematic. The use of intrageon's hands during the procedure. In order to reduce technical difficulty and radiation exposure, it is necessary to compare the rigidity of intramedullary nail according to the number of distal interlocking screws. The purpose of study is to compare the stability of interlocking intramedullary nail according to the number of distal screws by means of torsional compliance measurements in the simulated humeral shaft fractures. Simulated fractures were made in 20 humora from 10 cadavera at the mid-junction of humeral shaft. All humora were fixated with titaium humeral nail system. Interlocking screws were placed at proximal and distal screw holes by standard procedure. Group I consisted of 10 humora fixated with one distal interlocking screw and group II consisted of 10 humora fixated with two distal intterlocking screws. Torsional compliance was measured with single-end of 10 humora fixated with two distal interlocking screws. Torsional compliance was measured with single-end double arm torquing machine. The torsional compliance analog was 0.0294+/-0.0033 mm/N mm for one screw and 0.0241+/-0.0045 mm/N mm for two distal screws. The torsional compliance analog between two groups was found to be statistically insignificant(p=0.23). In conclusion, One distal interlocking screw was not inferior to two interlocking screws in terms of biomechanical characteristics, especially torsional compliance analog.
Arm ; Compliance ; Fracture Fixation, Intramedullary* ; Fractures, Comminuted ; Hand