title: Tendon transfer fixation in the foot and ankle: a biomechanical study evaluating two sizes of pilot holes for bioabsorbable screws.
abstract: The purpose of this study was to compare the initial fixation strengths of bioabsorbable screws for tendon transfers in the foot and ankle when the pilot hole size varied. A 7 x 20 mm screw was used with 5.5 mm and 6.5 mm drill holes, and a 5 x 20 mm screw was used with 3.9 mm and 4.5 mm drill holes. Biomechanical testing was performed on each tendon transfer in cadaver specimens. A paired t-test showed no significant difference in pullout strength when pilot hole size varied between 79 to 93% of the screw size for the 7 mm screw and 78 to 90% of the screw size for the 5 mm screw. Previous studies have found a critical value of tendon tension equaling 50 N with passive dorsiflexion of the foot. With an average value of approximately 170 N, the 7 mm screw provided three times the requisite strength. The 5 mm screw provided 1.5 times the requisite strength, but the transfer was technically more difficult.
authors.affiliation: Department of Orthopaedics, University of Texas Health Science Center at Houston, USA.
authors.forename: Keith W
authors.initials: KW
authors.lastname: Louden
authors.forename: Catherine G
authors.initials: CG
authors.lastname: Ambrose
authors.forename: Stacy G
authors.initials: SG
authors.lastname: Beaty
authors.forename: William C
authors.initials: WC
authors.lastname: McGarvey
authors.forename: Thomas O
authors.initials: TO
authors.lastname: Clanton
mesh_terms: D020341:Absorbable Implants; D000368:Aged; D000369:Aged, 80 and over; D000842:Ankle / Q000601:surgery*; D001696:Biomechanical Phenomena; D001863:Bone Screws; D002102:Cadaver; D005528:Foot / Q000601:surgery*; D006801:Humans; D013709:Tendon Transfer / Q000295:instrumentation / Q000379:methods*