As it remains unproven that hypermobility of the first tarsometatarsal joint (TMTJ-1) is a significant factor in hallux valgus deformity, the necessity for including arthrodesis of TMTJ-1 as part of a surgical correction of a hallux valgus is questionable. In order to evaluate the role of this arthrodesis on the long-term outcome of hallux valgus surgery, a prospective, blinded, randomised study with long-term follow-up was performed, comparing the Lapidus procedure (which includes such an arthrodesis) with a simple Hohmann distal closing wedge metatarsal osteotomy. The study cohort comprised 101 feet in 87 patients: 50 feet were treated with a Hohmann procedure and 51 with a Lapidus procedure. Hypermobility of TMTJ-1 was assessed pre-operatively by clinical examination. After a mean of 9.25 years (7.25 to 11.42), 91 feet in 77 patients were available for follow-up. There was no difference in clinical or radiological outcome between the two procedures. Also, there was no difference in outcome between the two procedures in the subgroup clinically assessed as hypermobile. This study does not support the theory that a hallux valgus deformity in a patient with a clinically assessed hypermobile TMTJ-1 joint requires fusion of the first tarso-metatarsal joint.

Cite this article: Bone Joint J 2013;95-B:1222–6.

The aetiology of hallux valgus is well published and largely debated. Hypermobility at the TMTJ was initially described by Morton, but it was not till Lapidus that its association with hallux valgus was hypothesized. However, little has been published on the anatomy of the tarsometatarsal joint. Our aim was to determine whether there was an anatomical basis for the coronal hypermobility in hallux valgus. Method. Anatomical dissection was completed on 42 feet from 23 bodies. Presence of hallux valgus was noted (displacement of sesamoids). Measurements and photographs were taken of the first tarsometatarsal joint and all differences noted. Observations. The TMTJ articular morphology is variable. There were 3 separate subtypes identified of the metatarsal articular surface. Results. The articular subtypes identified were called called A, B and C. Type A, was uni-facet with a single flat articular surface, Type B was bi-facet with two distinct flat articular surfaces, and Type C was tri-facet, with the presence of a lateral eminence on inferolateral surface of metatarsal. Type A was found exclusively in bodies with Hallux Valgus and Type C exclusively in bodies without Hallux Valgus. Type B was found in both groups. Type C was more common in males and type B was more common in females. The third facet was much more common in men. Another anomaly was found; measurements taken from the lowest to highest point of joint surface (mm) revealed a significantly flatter joint surface in bodies with hallux valgus. Conclusion. Coronal plane motion in varus is a consistent feature of hallux valgus. The lateral eminence acts as a sliding dovetail joint and prevents coronal plane motion and rotation. We believe we have identified a joint type that is protective of the development of hallux valgus