Introduction: There are very few data on baropodometric semiology in hallux valgus. Based on the analysis of fore-foot cases, we will try to show if there are early baropodometric signs of perturbation of support by the first ray.

Material: We compared clinical, radiological and baropodometric data from 105 feet (35 women, 18 men, average age: 55). The MT1/MT2 angle measured 1.26° to 22.02°, with an average of 11.94°, standard deviation 3.65. The MT1/MT5 angle was 15.04° to 39.56° with an average of 28.13°, standard deviation 4.76.

Methods: We recorded angles and differences in the lengths of metatarsi on anteroposterior X-rays. A Novel platform and its Emed software (Munich, Germany) enabled to record ground forces. We divided into ten weight-bearings zones: rear and mid-foot, the five metatarsi, the hallux, the second toe and the lateral toes. For each zone, we studied the distribution of the integral force time (IFT) and the instant of the step when the greatest force and pressure occurred. We compared those three criteria with the MT1/MT2 angle and the type of functional complaint from the patient.

Results: For the metatarsal zones, we identified four types of « baropodometric » populations depending on the radiological and clinical analysis. The asymptomatic population had maximal IFT on the medium metatarsi, and the instant of greatest simultaneous force and pressure was in the last quarter of the weight-bearing phase. The second population was the asymptomatic population with maximal IFT on the head of the first metatarsi, but the chronology of maximal force and pressure had no perturbation. The third type was a very symptomatic population with a higher IFT on MT1, for which the greatest ground force occurred very early compared with the other metatarsi (at about the middle of the weight-bearing phase). The fourth population had no systematic pattern for IFT or maximal ground forces phases.

Discussion: The development of a hallux valgus leads to an increase in the load of the head of MT1 (increase in the IFT). Then, as the deformity worsens and the meta-tarsosesamoid dislocates, weight-bearing on the first ray occurs earlier, with the diaphysis of MT1 before leading to a total disorganisation of the chronological phases of the forefoot.

Conclusion: Dynamic baropodometric study of the fore-foot can predict if a hallux valgus will worsen, and if our correction will remain stable.