Comparison of Transverse and Coronal Plane Stability at the First Tarsal-Metatarsal Joint With Multiple Screw Orientations.

Intercuneiform instability has been recognized as a potential cause of hallux valgus recurrence following tarsal-metatarsal joint (TMTJ) fusion. Recommendations have been made for additional screw placement between the metatarsals and/or the cuneiforms to improve stability. The screw orientation that provides the best stability has not been documented. Twelve cadavers with the first TMTJ fixated were used for testing. Using a consistent force application of 15 pounds in both the transverse and coronal planes, we measured the change in intermetatarsal angle on radiographs. Force testing was repeated with screws deployed individually in the following orientations: first to second cuneiform (CC), first to second metatarsal (MM), and first metatarsal to middle cuneiform (MC). Our results indicate that stability of the first ray in the transverse and coronal planes is not improved with TMTJ fixation alone or with an additional CC screw. The MM screw consistently reduced first metatarsal instability in both planes. The MC screw had intermediate results. These findings strengthen the notion that first ray instability is complex and involves the tarsal and metatarsal articulations at multiple levels outside of the TMTJ alone.

LEVELS OF EVIDENCE: Diagnostic and Therapeutic, Level IV: Cadaveric Study.