Overstuffing of Unstable Scaphoid Nonunions: A Radiographic Analysis of Carpal Parameters

Purpose: The purpose of this study was to radiographically evaluate scaphoid length and carpal parameters before and after reconstruction of nonunions with interposition vascularized medial femoral condyle (MFC) bone graft to determine if the scaphoid was overstuffed or if normal anatomy was restored and to determine the effect on ulnar carpal translocation when the volar radiocarpal ligaments were left unrepaired. Methods: Thirty-nine patients with established scaphoid nonunions with carpal collapse were reconstructed by interposition vascularized MFC bone grafts without repair of the volar radiocarpal ligaments. Pre- and postoperative radiographs and computed tomography scans of the 39 patients were reviewed. The scaphoid length, capitate-ulnar distance ratio (CUDR), modified carpal height ratio (MCHR), radiolunate (RL) and scapholunate (SL) angles were measured before and 3 months after surgery. Thirteen of these patients had contralateral wrist radiographs that were used for analysis of scaphoid length restoration. Results: No significant changes were observed for CUDR and MCHR before and after surgery. The length of the scaphoid significantly improved after reconstruction from 21.9 ± 3.3 to 23.7 ± 3.4 mm on posteroanterior x-ray views and from 24.0 ± 2.2 to 27.7 ± 2.8 mm on lateral views. The RL and SL angles also changed significantly after surgery from 19.5° ± 13.5° to 4.1° ± 16.9° and from 67.5° ± 12.5° to 56.0° ± 12.5°, respectively. Regarding the 13 patients with contralateral x-rays, no differences were seen on CUDR, MCHR, or scaphoid length on posteroanterior x-ray views. However, the scaphoid length on lateral x-ray views increased from 23.1 ± 2.40 to 27.6 ± 2.78 mm and was significantly longer than the contralateral side by 9.6%. The RL and SL angles were restored and comparable with the contralateral side. Conclusions: The use of vascularized MFC bone graft increased scaphoid length by 9.6% and restored normal carpal alignment. Despite the increased scaphoid length compared with the contralateral side, the lack of repair of the volar radiocarpal ligaments did not cause ulnar carpal translocation in short-term follow-up. Type of study/level of evidence: Therapeutic IV.