Three-dimensional deformity study of affected ulna in children with chronic anterior dislocation of radial head

Abstract

Objective To explore the three-dimensional deformity of affected ulna in children with chronic anterior dislocation of radial head , provide pathological changes of the disease and guide clinical surgery. Methods There were 7 cases of chronic anterior dislocation of radial head of Monteggia fracture. There were 5 boys and 2 girls with an average age of 8(3-11) years. All belonged to Bado type Ⅰ. The average time from trauma to surgery was 29 (12-48) months. Bilateral ulna and radius were scanned with three-dimensional computed tomography (CT). The data were transferred using MIMICS10.01 software. By using the mirroring technology, ipsilateral ulna and contralateral ulna were compared at the levels of sagittal, coronal and axial positions. Results All cases of affected ulna had three-dimensional deformity in coronal, sagittal and axial positions. Hyperextension deformity was the most obvious in sagittal position. The average angle was 16.26 (12.14-20.83) degrees; the average coronal deformity 10.24(5.44-12.90) degrees; the average axial rotation deformity 13.14 (6-23) degrees. Conclusions Obvious three-dimensional deformities exist in affected ulna in children with chronic anterior dislocation of radial head. In clinical practice, it may be necessary to correct the extroversion and rotational deformity of lateral ulna at the same time so as to completely correct the deformity of lateral ulna and prevent the postoperative dislocation of radial head. Key words: Radius; Dislocations; Ulna; Child