Acute plastic deformation of forearm is rare in adults，different from the mechanism of this injury in children, its main cause in adults is industrial accident, usually entrapment on moving rollers in machines[1]. Treatment to this injury including manipulation reduction with cast fixation, corrective osteotomy with plate or intramedullary nail fixation. The treatments have different disadvantages. We report in this article a new treatment to this injury, which is more effective, safe,exact and easy to conduct. This specific study was reviewed and approved by ethics committee of our hospital before the study began. We also got the participant’s written consent to have data from her medical records used in research.
Case report
A 24-year-old female sustained trauma on a slow moving roller machine. Her left hand entrapped in the roller and her left forearm subsequently was bent over it. She could extricate her limb only after the machine was stopped to slip off the roller which took about 2 minutes. On clinical examination, she presented swollen and tender left forearm. There was significant dorsal bowing deformity in forearm bones. The forearm movements were restricted between 10 pronation and 50 supination. The left forearm was 1.5cm shorter than the contralateral limb. Anteroposterior and lateral radiographs revealed radialis bowing of radius shaft(Fig. 1A,1B). Closed manipulation was attempted to straighten the forearm bones, but it was proved inadequate in reducing the forearm bowing. We performed three-dimensional printing preoperative planning and radius osteotomy external fixation to restore her forearm pronation and supination function.
Preoperative 3D-printing planning
We planned the one site osteotomy at radius to correct the rotational axis of the forearm. Surface data for the whole radius and ulnas of left forearm were obtained in Standard Triangulated Language (STL) format from CT Digital Imaging and Communications in Medicine (DICOM) data using surface reconstruction software. We considered that bowing deformity was present at the radius shaft. The osteotomy site was set almost at the peak of the bowing. We rotated the distal part of radius to reduce the distal radius and ulna joint and 3D-printed.(Fig. 2A,2B)
Surgical procedure
The range of pronation and supination remained limited with testing of passive range of motion under brachial plexus anesthesia. This revealed that the rotational axis of the forearm and the distal ulnar radial joints are abnormal. A straight incision about 1cm was applied on the middle part of radial side. Then approached to the radial shaft by a scissor. We determined the osteotomy line with reference to the 3D-printed model. Osteotomy using a drill bit of 2.0 mm diameter. Two parallel holes were drilled with the drill bit directed to the proximal radius. Screwed two screws, connect crossbar and angle adjuster. Next, two distal holes were drilled and two more screws were inserted to the distal radius with fixed-angle locking, the angle with reference to the 3D-printed model. Then remove the angle adjuster, rotated distal radius to open the osteotomy site and correct the rotational axis of the forearm. Range of pronation and supination were improved after the osteotomy procedure, then fixed all screws and crossbar as a whole. Radiography showed normal rotational axis of the forearm and perfect screw position. (Fig. 3A-C)
Post-operation treatment
Antibiotics were administered for 24 hours to prevent infection. We instructed the patient to perform functional exercise 24 hours after operation. External fixation was removed 3 months after operation. Bone union of the whole cortex was achieved (Fig. 4A,4B) and range of motion remained improved as of 10 mounths postoperatively. Full range of motion was achieved. Supination and pronation were measured at 90° and 60°, respectively (Fig. 5A,5B).