Describes metacarpal synostosis. Takes into account the shape of the metacarpal bones, the curvative of the epiphysis, and the length of the discrepancy in determining the need for surgical correction. I-shaped deformity, does not require surgery; U-shaped deformity, requires surgery when the 2 metacarpals are tightly fused or asymmetrical in length; Y-shaped synostosis, requires surgery; K-shaped (occurs only between the 4th and 5th metacarpals), should have osteotomy and distraction lengthening.