HALLUX-VALGUS, 1ST METATARSAL PRONATION AND COLLAPSE OF THE MEDIAL LONGITUDINAL ARCH - A RADIOLOGICAL CORRELATION

In a previous study we developed a model to assess first metatarsal pr onation based on the position of the inferior tuberosity of its base a nd showed a significant relationship between first metatarsal pronatio n and the intermetatarsal angle (r = 0.69, p<0.001). The present study was undertaken to correlate first metatarsal pronation with the heigh t of the medial longitudinal arch in an attempt to define the clinical significance of this new finding. The weight-bearing anteroposterior and lateral radiographs of the feet of 50 patients (100 feet; 36 femal es patients of mean age 38 years, 14 males patients of mean age 40 yea rs) were reviewed, and in each case, the patient's age, sex, intermeta tarsal angle, amount of first metatarsal pronation and medial longitud inal arch angle were recorded by independent observers. A significant relationship was demonstrated between first metatarsal pronation and t he height of the medial longitudinal arch (r = 0.93, p<0.0001). Less m arked association was observed between intermetatarsal angles and firs t metatarsal pronation (r = 0.71, p<0.001). Multivariate analysis of p atient age, sex, intermetatarsal angle and medial longitudinal arch an gle against metatarsal pronation showed that the single most dominant variable affecting metatarsal pronation was the height of the medial l ongitudinal arch.