External fixator pin insertion techniques: biomechanical analysis and clinical relevance.
A series of identically matched pairs of fresh-frozen canine femora (approximating human radii in size and dimension) were used to mechanically compare pull-out strength between 4 mm predrilled, self-tapping, half-pins and 4 mm self-drilling, self-tapping half-pins with drill bit-like cutting flutes. A second biomechanical and videotape analysis was done comparing the differences of pin insertion by power versus hand drilling. Results indicated a mean 22% reduction in bone purchase of self-drilling, self-tapping pins compared with that of predrilled pins and a marked increase in depth of insertion required of the self-drilling pins for comparable pin purchase (10 mm). It was also observed that a visible "wobble factor" exists, which tends to weaken the pin-bone interface when hand drilling is performed.
Seitz
W H
WH
Department of Orthopaedic Surgery, Mt. Sinai Medical Center, Cleveland, Ohio.
Froimson
A I
AI
Brooks
D B
DB
Postak
P
P
Polando
G
G
Greenwald
A S
AS
D000818:Animals; D001696:Biomechanical Phenomena; D001858:Bone Nails; D004285:Dogs; D016267:External Fixators; D005269:Femur / Q000503:physiopathology / Q000601:surgery; D005592:Fracture Fixation / Q000295:instrumentation / Q000379:methods*; D066298:In Vitro Techniques