BACKGROUND:The bony crista has been found in the distal humeral medullary cavity,but its specific morphological characteristics and clinical significance are not clear.OBJECTIVE:To study the morphology of bony crista inside the distal intramedullary of the human humerus and its potential clinical relevance.DESIGN,TIME AND SETTING:CT scanning and measurement as well as visualized observation to the specimen for the dry adult humeri was performed at CT Room and Department of Orthopaedics,First Affiliated Hospital,Nanchang University from June to December 2007.MATERIALS:A total of 80 dry adult humeri (left:49;right:31) were purchased from the Department of Anatomy,Medical College of Nanchang University,excluding the fractured and lesion humerus.METHODS:The low 1/3 of eighty human humeri were scanned by 16 layer spiral CT.The morphological features of the intramedullary bony prominence above the olecranon fossa was described in terms of coronal plane,sagittal plane and transverse section after three-dimensional reconstruction.The low 1/3 of twenty humeri were then split vertically in the middle line in coronal plane,to view the intramedullary bony crista directly.MAIN OUTCOME MEASURES:The bony crista mainly located on the medial or lateral side,the range of the bas'dar part of the bony crista,alinement characteristic of the bony crista.RESULTS:The extent of intramedullary bony crista ranged from 1.9 to 3.2 cm (mean 2.6 cm) above the olecranon fossa,the density similar to cortical bone,with an basement posterior,and medial part and lateral side intero-inferiody incline.59 out of the 80 humeri,medial side dorminated;on the rest humeri the lateral side dorminated.2 or 3 parallel lines on the dorminate side,irregular alignment on the other side.CONCLUSION:The study described the morphology of the distal intramedullary bony crista of the humerus,which has never been reported so far.In addition,its clinical relevance in terms of the internal fixation of fracture on the distal humerus and elbow arthroplasty was also demonstrated.