A "Hallux Valgus" or "Hallux Abducto-Valgus" deformity, is commonly referred to as a "Bunion." This describes a pathological condition involving the position of the "hallux" in relation to the first metatarsal.
A bunion deformity can clinically present with a variety of characteristics. The foot itself may present with a wide splaying of the forefoot and a painful bump on the medial aspect of the first metatarsal phalangeal joint. In addition, the hallux may be abducted from the midline of the body, with a valgus rotation in the frontal plane.
A radiographic analysis of a bunion deformity in the Anterior/Posterior or Dorsal/Plantar view will reveal a variety of pathological components. Most notably so, is the exaggerated inter-metatarsal angle between the first and second metatarsal. This may be accompanied by a displacement of the first metatarsal from its position over the sesamoids, such that the metatarsal demonstrates a medial alignment away from the sesamoids which lie to the lateral side.
In some cases, the proximal articular set angle at the head of the first metatarsal may be off-set. This "PASA" is one of the factors which determines the position of the proximal phalanx on the metatarsal during movement as well as at rest.
Although conservative care may involve shoe modifications, padding, strapping, and custom orthosis; surgical reconstruction may be required to alleviate painful and immobilizing bunion conditions.
Soft tissue components of the bunion deformity are primarily addressed by means of a capsular modification, as well as a tenotomy of the adductor tendon at its insertion on the base of the proximal phalanx. The fibular sesamoid may be repositioned by a release of the surrounding ligaments.
Surgical management of the bone or osseous components of a bunion deformity will commonly include an osteotomy and correction to re-establish a more functional position of the first metatarsal within the forefoot. This capital fragment of bone is held in place with hardware fixation in order to secure a proper alignment during the healing phase, thus allowing the hallux to return to a more functionally useful position in the sagittal plane.