Evaluate MTP joint congruity and degree of arthritis.
HV angle = angle between the long axes of the first metatarsal and proximal phalanx; normal<15 degrees.
intermetatarsal (IM) angle=angle between the first and second metatarsals; normal< 9 degrees
Hallux Varus Classification / Treatment
Hallux varus with painfree joint: Rx=dynamic correction using EHL or EHB.
Tenodesis-type transfer of the extensor hallucis brevis. The tendon is cut at its musculotendinous junction and transferred beneath the transverse metatarsal ligament proximally into the lateral aspect of the first metatarsal. Medial release of the abductor hallucis and medial capsule may also be necessary. The transfer is a static tenodesis and does not function dynamically. Myerson MS, Komenda GA: Results of hallux varus correction using an extensor hallucis brevis tenodesis. Foot Ankle Int 1996;17:21-27.
If IP joint does not have fixed deformity a split EHL transfer with medial capsulotomy can be used. (Johnson KA, Spiegl PV: Extensor hallucis longus transfer for hallux varus deformity. J Bone Joint Surg 1984;66A:681-686)
Hallux Varus with translation of the metatarsal head: if prior bunion correction caused excessive translation of the metatarsal head, osteotomy is required to place proximal phalanx in a congruent position. Medial capsule release and splint extensor hallucis longus transfer into the proximal phalanx, under the intermetatarsal ligament laterally.