Mobility of the first ray: review article.

Since its introduction by Morton in the early 20th century, first metatarsal instability has been debated as a contributing cause of many foot ailments. Given our evolutionary origins, some instability at the first ray seems inevitable. It makes sense that hypermobility could be the pathology leading to the development of various forefoot disorders. The problem is that it has been difficult to prove. Only in the last decade have there been any devices with which to quantify mobility, and each of the devices measures slightly different variables. However, each of these devices has been shown to be consistent and reliable. Excessive mobility of the first ray probably cannot be considered the only "suspect." With disorders such as hallux valgus and metatarsalgia, environment and footwear may play just as important a role as hypermobility. There are some conclusions, though, that can be safely drawn at this point. * We should define the measures of first ray mobility. One recent study has suggested the terms metatarsal elevation and metatarsal translation to describe two different aspects of the problem. * Simple clinical tools may be as useful as more cumbersome research tools for assessing first ray instability. * First ray mobility on average is increased in patients with hallux valgus. * First ray mobility is increased in some patients with transfer metatarsalgia. * Although some studies show increased elevation or mobility of the first ray in hallux rigidus, other studies do not. The burden is on the current generation of foot and ankle practitioners to resolve the debate of its predecessors. By first defining the measures of instability and then applying them to large populations, the role of hypermobility may be better defined. Then we can debate how best to "fix" the problem!