Anatomical study of Lapidus arthrodesis using two different plantar plate systems.

Background: First tarsometatarsal arthrodesis (modified Lapidus procedure) constitutes a sufficient treatment for moderate to severe hallux valgus deformity and first ray instability. The plantar plate arthrodesis was shown to provide superior mechanical stability and less postoperative complications than screw fixation or dorsal plating. Nevertheless, the in-brought hardware may cause irritation of the tibialis anterior or peroneus longus tendon requiring explantation of the material in some cases. The purpose of this study was to investigate the potential of tendon irritation after plantar first tarsometatarsal joint arthrodesis in a cadaver study.

Methods: Plantar plate arthrodesis was performed as in real surgery on twelve pairs of fresh frozen cadaveric feet. Two different plate systems were randomly allocated to each pair of feet. After plate fixation careful dissection of the feet followed to analyze potential tendon irritation and to determine a "safe zone" for plantar plate placement.

Results: A "safe zone" between the insertion sties of tibialis anterior and peroneus longus tendon was found and proven to be sufficiently exposed using a standard medio-plantar approach. Both plates were fixed in this zone without compromising central tendon parts. Peripheral tendon parts were irritated in 42% using Darco Plantar Lapidus Plating System® (Wright Medical, Memphis, TN) and in 8% using the Plantar Lapidus Plate® (Arthrex, Naples, FL). Bending of the anatomically preshaped plates is often necessary to ensure optimal fit on the bone surface.

Conclusions: Modified Lapidus procedure with plantar plating of the first tarsometatarsal joint can be performed safely without compromising central tendon parts via standard medio-plantar approach.

Level Of Clinical Evidence: 5, Cadaver Study.