PREVENTION OF FRACTURE AT THE DISTAL LOCKING SITE OF THE GAMMA-NAIL

To investigate the origin of fractures at the distal locking site of t he Gamma nail, we loaded ten paired human cadaver femora fixed with a Gamma nail in torsion until they fractured. When an aml was hammered i n to start the hole for distal locking a fissure appeared in the later al cortex of all the femora, and the mean torsional load to create a f racture was reduced by 57.8% compared with that in a control group in which the distal locking hole had been started with a centre drill. Wh en an additional drill hole was made, the mean failure load in torsion decreased by 35.7%. We strongly recommend that an awl should not be u sed at the distal locking site of the Gamma nail; we recommend the use of a centre drill. Additional drill holes should be avoided because t hey act as stress raisers.