BACKGROUND: To correct a hallux valgus (HV) deformity quantitatively and prevent unexpected postoperative deformity, the center of rotation of angulation (CORA) method was applied during HV surgery. To correct a hallux valgus (HV) deformity quantitatively and prevent unexpected postoperative deformity, the center of rotation of angulation (CORA) method was applied during HV surgery. METHODS: To create a normal foot model, radiographs of 64 normal female feet were measured. Points A and B were defined as the intersection of the intermetatarsal angle and the HV angle. CORA1 and CORA2 were defined as the intersection of the axes of the first metatarsal and the first proximal phalanx in the normal and HV models, respectively. Procedures to correct HV deformity using the CORA method were devised and were applied to HV feet, which underwent a focal dome osteotomy or medial wedge osteotomy. RESULTS: Point A was 2.3 times the length of the second metatarsal proximally from the top of the second metatarsal head, and point B was 0.17 times the length of the first metatarsal proximally from the top of the first metatarsal head. Two methods were used to correct the deformity. With one method, a focal dome osteotomy was performed at the first metatarsal on the circle at the CORA1 and the distal fragment was moved to the standard first metatarsal axis. The first proximal phalanx was then moved around the metatarsal head to the standard axis of the first proximal phalanx at the CORA2. With the other method, a medial wedge osteotomy was performed on or proximal to the CORA2, and the distal fragment was moved to the first standard metatarsal axis. CONCLUSIONS: We propose a preoperative plan to use the CORA method to correct deformities that prevent translation of the axis or an angulation deformity. HV deformity can be corrected effectively using the CORA method.
BACKGROUND: To correct a hallux valgus (HV) deformity quantitatively and prevent unexpected postoperative deformity, the center of rotation of angulation (CORA) method was applied during HV surgery. To correct a hallux valgus (HV) deformity quantitatively and prevent unexpected postoperative deformity, the center of rotation of angulation (CORA) method was applied during HV surgery. METHODS: To create a normal foot model, radiographs of 64 normal female feet were measured. Points A and B were defined as the intersection of the intermetatarsal angle and the HV angle. CORA1 and CORA2 were defined as the intersection of the axes of the first metatarsal and the first proximal phalanx in the normal and HV models, respectively. Procedures to correct HV deformity using the CORA method were devised and were applied to HV feet, which underwent a focal dome osteotomy or medial wedge osteotomy. RESULTS: Point A was 2.3 times the length of the second metatarsal proximally from the top of the second metatarsal head, and point B was 0.17 times the length of the first metatarsal proximally from the top of the first metatarsal head. Two methods were used to correct the deformity. With one method, a focal dome osteotomy was performed at the first metatarsal on the circle at the CORA1 and the distal fragment was moved to the standard first metatarsal axis. The first proximal phalanx was then moved around the metatarsal head to the standard axis of the first proximal phalanx at the CORA2. With the other method, a medial wedge osteotomy was performed on or proximal to the CORA2, and the distal fragment was moved to the first standard metatarsal axis. CONCLUSIONS: We propose a preoperative plan to use the CORA method to correct deformities that prevent translation of the axis or an angulation deformity. HV deformity can be corrected effectively using the CORA method.