Fracture of a bipartite medial cuneiform synchondrosis.

We report the occurrence of a bipartition and occult growth plate fracture in the medial cuneiform of a 5-year, 11-month-old traumatic amputee. Initial radiographs of the foot taken in an oblique projection revealed what appeared to be an osseous fracture of the medial cuneiform. Histologic examination of the pathologic specimen showed that the radiolucent cleft separating the two foci of ossification was actually a hyaline synchondrosis (growth plate) functioning in the normal endochondral transformation of the bone. Histology also detailed a previously undetected fracture traversing the synchondrosis that was sustained during the accident. This unusual case demonstrates that radiographic discontinuity often does not correspond to anatomic discontinuity and should not be misdiagnosed as an osseous fracture. Yet, as with all growth plates of the chondro-osseous skeleton, occult injury to the growth mechanism should be suspected in instances of obvious trauma. Discriminating between normal development of the skeleton and skeletal pathology can be a challenge to the treating physician. Therefore, an awareness of possible anatomic variations will enhance diagnostic evaluations.