Beware the hallucal interphalangeal joint sesamoid in first metatarsophalangeal joint arthrodesis.

BACKGROUND: We describe a previously unreported presentation of the hallucal interphalangeal joint sesamoid (HIPJS) following arthrodesis of the first metatarsophalangeal joint (MTP1).

METHODS: Of 438 MTP1 arthrodeses performed over a 13-year period, 12 feet returned with a painful keratoma beneath a gradually hyperextending interphalangeal joint of the great toe (IPJ1) from unexcised, unrecognized or recognized HIPJS. We identified another 7 feet with HIPJS, which did not develop symptoms after MTP1 arthrodesis. Angles at which arthrodesis had been performed were measured.

RESULTS: All big toes had been arthrodesed in good position, clinically and radiologically, with no difference between the two groups in angles subtended by the proximal phalanx of the arthrodesed big toe with the ground. Good outcomes followed surgical excision of the symptomatic HIPJS.

CONCLUSIONS: The presence of a HIPJS should be excluded in the differential diagnosis of IPJ1 symptoms developing after MTP1 arthrodesis. Furthermore, one should look out for and consider prophylactic excision of a HIPJS at time of MTP1 arthrodesis.