First metatarsophalangeal joint arthrodesis: current fixation options.

This article reviews the current literature on first metatarsophalangeal joint arthrodesis rates using various forms of fixation, as well as reviewing biomechanical studies comparing the strengths of the different fixation options that are available.

Lapidus arthrodesis with a single lag screw and a locking H-plate.

The aim of this pilot study was to assess if using an interfragmental lag screw and a Darco(®) locking H-plate for the modified Lapidus arthrodesis in the treatment of hallux abducto valgus deformity (1) would allow for earlier weight bearing than previously described and (2) would indicate whether any changes would occur radiographically with the earlier weight bearing. Twenty-one metatarsocuneiform arthrodeses, in 18 patients, were retrospectively evaluated through chart review and postoperative radiographs. Original diagnoses included painful hallux abducto valgus and osteoarthritis of the first metatarsocuneiform joint. The mean age of the patients was 48 (range, 16 to 70) years. The mean follow-up duration was 38.5 (range, 29 to 60) months. The overall radiographic osseous union rate was 90.5% (19/21 feet), although there were 2 asymptomatic nonunions. There were no cases of fixation failure, and the surgical correction was preserved on follow-up radiographs. Overall, the mean time to full weight bearing was 4.7 (range, 3 to 7.5) weeks, and it was a mean of 8 (range, 7 to 10) weeks before the patient was back to wearing comfortable shoes. The authors concluded that metatarsocuneiform arthrodesis fixated with 1 interfragmentary lag screw and a Darco(®) locking H-plate provides sufficient stability to allow earlier weight bearing than has been previously described with other internal fixation constructs.

Analysis of screw pullout strength: a function of screw orientation in subtalar joint arthrodesis.

The purpose of this cadaveric study was to compare the pullout strength and failure load of 2 different screw orientations for subtalar arthrodesis. Twenty-six specimens from 13 cadaver donors (1 left and 1 right each) were used. A 7.3- x 65-mm long-thread profile (32-mm length) cannulated screw inserted into the calcaneus from dorsal to plantar (calcaneal specimens) was compared with a 7.3- x 65-mm short-thread profile (16-mm length) cannulated screw inserted into the talus from plantar to dorsal (talar specimens). A torque screwdriver with a calibrated electronic vernier scale measured the torque of screw insertion. Screw pullout strength and load failure were measured by using a servohydraulic materials testing machine. Distraction was applied along the axis of the screw at a displacement rate of 25 mm/min. The peak torque of insertion in all calcaneal specimens was reached on initial insertion through the dorsal subchondral bone plate of the calcaneus; in talar specimens, it was reached as the screw threads were completely buried into the talus. A significant difference (P = .00647) was found between the mean torque of insertion for the calcaneal (1.50 Nm) and talar specimens (1.30 Nm). A comparison of pullout forces showed a significantly stronger mean failure load for calcaneal specimens (P = .000085). The mean failure load for paired calcaneal specimens was 1782 N compared with a mean 1245 N for talar specimens. Although the pullout force was clearly greater in the dorsal-to-plantar screw application, the pullout force in the plantar-to-dorsal orientation was also considerable.