OBJECTIVETo analyze the correlation between the hallux valgus angle and arch X-ray parameters change, plantar pressure by measuring the X-ray indexes and foot-pressure indexes in patients with hallux valgus, as well as to study the main cause factors for the pain under the second metatarsal head.

METHODSA retrospective study of 254 patients(477 feet) treated in Wangjing Hospital from January 2012 to June 2013 was performed. The pain under the second metatarsal head and age distribution were recorded. All the patients were divided into two groups according to the second plantar bone pain: pain group and no pain group. The following indexes were measured and compared: HAVA(hallux abductor valgus angle), IMA1-2(the inter-metatarsal angle between the first and second metatarsals), IMA1-5(the inter-metatarsal angle between the first and fifth metatarsals), TAOTMLA (top angle of the medial longitudinal arch), AAOTMLA (anterior angle of the medial longitudinal arch), SMRL (the second metatarsal relative length than the first), and the plantar pressure indicators including TPUM (touch the ground time percentage under the second metatarsal head), PPUM (peak pressure under the second metatarsal head), and IUM(impulse under the second metatarsal head). All the factors were evaluated by Logistic regression analysis.

RESULTSSpearman rank correlation test showed that there were statistical significance in correlation between HAVA and IMA1-2, IMA1-5, TAOTMLA, AAOTMLA, TPUM(<0.05, r=0.647, 0.553, 0.127, -0.165, 0.158). Factors including the HAVA, SMRL and the TPUM were the risks for the pain under the second metatarsal head in patients with hallux valgus(<0.05, ORj=1.030, 1.069, 1.060).

CONCLUSIONSIncrease of the hallux valgus angle causes the collapse of hallux valgus arch, extending the weight bearing time of the second metatarsal and increasing the possibility of the pain under the second metatarsal.