The first tarsometatarsal joint and its association with hallux valgus

Abstract

IntroductionThe aetiology of hallux valgus is almost certainly multifactoral. The biomechanics of the first ray is a common factor to most. There is very little literature examining the anatomy of the proximal metatarsal articular surface and its relationship to hallux valgus deformity.MethodsWe examined 42 feet from 23 specimens in this anatomical dissection study.ResultsThis analysis revealed three distinct articular subtypes. Type 1 had one single facet, type 2 had two distinct articular facets, and type 3 had three articular facets one of which was a lateral inferior facet elevated from the first. Type 1 joints occurred exclusively in the hallux valgus specimens, while type 3 joints occurred exclusively in normal specimens. Type 2 joints occurred in both hallux valgus and normal specimens. Another consistent finding in regards to the proximal articular surface of the first metatarsal was the lateral plantar prominence. This prominence possessed its own articular surface in type 3 joints and was significantly flatter in specimens with hallux valgus (p < 0.001) and the angle with the joint was significantly more obtuse (p < 0.001).ConclusionsWe believe the size and acute angle of this prominence gives structural mechanical impedance to movement at the tarsometatarsal joint and thus improves the stability.

Interpretation of variant morphological patterns in the hallucal cuneometatarsal joint

“…The triple-faceted first cuneometatarsal joint was only recently identified in clinical (Mason and Tanaka, 2012) and skeletal analyses (this study) of humans, and has not been identified in other extant hominoids or fossil hominins to the best of our knowledge. In light of the differential orientation and curvature of multiple facets at the joint and clear association between facet number and hallux valgus (Mason and Tanaka, 2012), two-and three-faceted first cuneometatarsal joints are likely to be associated with an increasingly diminished mobility of the hallux.…”

“…Indeed, we are unaware of any published examples of tripartite medial cuneiforms embyrologically or otherwise. The three faceted pattern at the hallucal cuneometatarsal joint has not been described in the literature until recently noted in a study on facet forms and hallux valgus (Mason and Tanaka, 2012).…”

“…In research on hallux valgus deformity, a disorder characterized by lateral deviation of the hallux, Mason and Tanaka (2012) identified a correlation with facet patterning at the hallucal tarsometatarsal joint. They classified the joint as unifacet, bifacet, or trifacet in 41 dissected feet.…”

“…The rarity of the unifacet pattern, often noted as one of the most frequently occurring patterns at the hallucal tarsometatarsal joint (Singh, 1960;Jeyasingh et al, 1981;Ajmani et al, 1984;Zipfel, 2004) is surprising, as is the high rate of trifacets. The cadaver sample studied by Mason and Tanaka (2012) consists exclusively of elderly individuals with a range of 66-104 years of age (mean = 86 years), an age profile that is likely to differ from many, if not most, archaeological and anatomical samples. The association of hallux valgus, an ageprogressive deformity (Nix et al, 2010), with facet number at the first cuneometatarsal joint and alongside the high frequencies of double and triple facets at the joint in the elderly sample studied by Mason and Tanaka (2012), warrants further investigation.…”

“…Potential intra-and inter-specific variation in first tarsometatarsal facet patterns hold possible implications for understanding the development of the foot in fossil hominins (Jashashvili et al, 2010), the reconstruction of habitual behavior in hominoids (e.g., Tocheri et al, 2011) and even the predisposition to foot pathology in modern humans (Mason and Tanaka, 2012).…”