OBJECTIVE: To observe the clinical efficacy of two surgical methods for the treatment of moderate-to-severe bunion deformity. METHODS: From January 2007 to June 2010, 173 cases (297 feet) with moderate-to-severe bunion deformity were treated by fusion of the first metatarsal cuneiform joint and basal oblique cuneiform osteotomy. Preoperatively, two groups were divided according to the presence or absence of transverse arch collapse and the mobility of the first metatarsophalangeal joint. Those with transverse arch collapse and hypermobility of the first metatarsal cuneiform joint (group A) underwent fusion of the first metatarsal cuneiform joint and soft tissue balancing surgery; those without transverse arch collapse and stable first metatarsal cuneiform joint (group B) underwent oblique wedge osteotomy of the first metatarsal base and soft tissue balancing surgery. The AOFAS score was used to evaluate the function of the affected foot, and the front and side X-rays in weight-bearing position were also taken for imaging evaluation, and the seed bone position, metatarsal length, HVA, IMA and AOFAS scores were recorded before and after surgery. The results were statistically analyzed using SPSS17. 0. RESULTS: In this group, 142 cases were obtained for follow-up, 69 cases in group A with 109 feet and 73 cases in group B with 124 feet. In group A, the excellent rate was 90.1%, and the AOFAS score improved from the preoperative average of 39 to 88; in group B, the excellent rate was 87.9%, and the AOFAS score improved from the preoperative average of 41 to 85. There was no significant difference in seed bone position, HVA, and IMA between the two groups after surgery; there was a significant difference in the change of metatarsal length between the two groups of cases before and after surgery. DISCUSSION: The key to determining the surgical outcome is to ensure effective downward compression of the first metatarsal head, avoid excessive shortening of the first metatarsal and restore the stability of the first sequence. Stability of the coronal and sagittal planes must be ensured. When bunion is accompanied by instability of the first cuneiform joint, it is often manifested by inversion of the first metatarsal, enlargement of the IMA, collapse of the transverse arch of the foot, reduction of weight-bearing of the first metatarsal and excessive weight-bearing of the central metatarsal head, and formation of anterior metatarsalgia and painful callus in the long run, for this kind of bunion deformity, it is difficult to correct the imbalance of weight-bearing function of the forefoot caused by instability of the first metatarsal cuneiform joint by simple surgery of the first metatarsal joint and osteotomy of the first metatarsal. The fusion of the first metatarsal cuneiform joint is necessary to obtain a good therapeutic effect. Conclusion: First metatarsal cuneiform joint fusion and basal oblique wedge osteotomy are both effective methods for the treatment of moderate to severe bunion deformity. However, according to the state of the forefoot transverse arch, the mobility of the first metatarsal cuneiform joint and the length of the first metatarsal bone, the corresponding surgical method should be used to restore the normal biomechanical state of the patient in order to obtain good clinical results.