THE COURSE OF THE METATARSAL BREAK ANGLE (MBA) IN FOREFOOT ARTHROPLASTY: A PROSPECTIVE STUDY

Abstract

Some patients following operation for Hallux Valgus deformity develop Transfer Metatarsalgia. Many believe that a long oblique osteotomy of the second metatarsal as part of surgical correction of Hallux Valgus deformity reduces the risk of developing transfer metatarsalgia.

Metatarsal Break Angle (MBA) is the angle subtended by one line from the centre of the head of First Metatarsal to the centre of the head of the Second Metatarsal and another from the centre of the head of the Second Metatarsal to the centre of the head of Fifth Metatarsal. The MBA changes following osteotomy of the Second metatarsal.

Is the Metatarsal Break Angle(MBA) altered in patients who undergo long oblique osteotomy of the second metatarsal?. Literature does not mention anything to this effect. We prospectively studied the course of this angle in patients who underwent osteotomy of the second metatarsal at the same time as they had surgical correction of their painful Hallux Valgus deformity.

Twenty-four consecutive patients (thirty-one feet), nineteen Female and five Male, in the age range of eighteen to seventy-one years successfully fulfilled the inclusion criteria. The inclusion criteria being - Hallux Valgus deformity with a dorsally subluxed second Meta-tarsaophalangeal joint(MTPJ) and presence of tenderness/hyperkeratotic plantar patch at the second MTPJ.

The postoperative range of increase in the angle was two to sixteen degrees in all except one patient (decreased by one degree). Median change was eight degree increase. This study concludes that the MBA is altered in patients who undergo long oblique osteotomy of the second metatarsal. This type of osteotomy done so as to provide the head of the second metatarsal a fresh plantar fat pad to rest upon does help to remove the tenderness over the second MTPJ.

To the best of our knowledge this change in MBA has not been mentioned in the medical literature and we believe that our study highlights this important geometrical change in the architecture of post-operative forefoot.