Effect of proximal articular set angle-correcting osteotomies on the hallucal sesamoid apparatus: a cadaveric and radiographic investigation.

Abstract

A cadaveric and radiographic study was undertaken to demonstrate the change in intersesamoidal crista architecture after an osteotomy that corrects the proximal articular set angle (PASA). Three cadaveric first metatarsals with hallux valgus deformity were utilized. Separate Kirschner wires representing the longitudinal axis bisection, PASA, and the long axis of the crista were placed into each specimen. After osteotomy, the metatarsal heads were translated laterally, rotated parallel to the transverse plane to correct PASA, and impacted. The relationship between the crista and the long axis of the metatarsal was determined. A deviation in the alignment between the intersesamoidal crista and the long axis of the metatarsal following the osteotomy was observed. The radiographic portion of this study correlated intermetatarsal angle, PASA, and tibial sesamoid position with intersesamoidal crista appearance on sesamoidal axial radiographs. Radiographic parameters in 19 patients (34 feet) were compared and two distinct patterns were evident: 1) A proximal articular set angle greater than 15 degrees was associated with complete crista erosion in 10 feet (91% of this subgroup); 2) a tibial sesamoid position greater than three was associated with partial or complete erosion in 17 feet (100% of this subgroup). A higher deviation of PASA and increased displacement of the sesamoidal apparatus correlated with crista erosion. These findings suggest that the crista fails to adapt with PASA as hallux valgus progresses and undergoes erosion instead. This study suggests that when correcting the PASA, misalignment of the sesamoid apparatus may lead to sub-first metatarsal arthrosis.