Mobility of the first tarsometatarsal joint in hallux valgus patients: a radiographic analysis

Hypermobility of the first tarsometatarsal (TMT 1) joint in the sagittal plane plays a role in the etiology and treatment of the hallux valgus complex. However, objective quantification of this mobility is still a problem. We performed a radiographic analysis of TMT 1 mobility in the sagittal plane in 94 hallux valgus patients aged 15 to 65 years. We examined 94 feet with symptomatic hallux valgus deformity requiring operative correction. Excluded were patients with osteoarthritis, inflammatory diseases or previous operations on the foot. The TMT 1 mobility was tested with a clinical test and by radiographic measurement using the modified Coleman block test. The mean mobility of the TMT 1 joint in the sagittal plane in the patient group was 12.9 degrees (SD 4.80). In addition, there was a statistically significant difference between two subgroups: patients with and without clinical TMT 1 hypermobility. No correlation of TMT 1 (hyper)mobility and radiographic second ray hypertrophy was found. This simple method can produce additional information to the clinical TMT 1 hypermobility test in the sagittal plane.