Assessment of Ulnar Carpal Translocation and Carpal Alignment After Volar Plate Fixation With Vascularized Bone Graft for Scaphoid Waist Fracture Nonunions.

Purpose: Multiple fixation methods with or without vascularized graft have been described to treat scaphoid nonunions. This study aimed to assess the incidence of carpal malalignment and the degree of ulnar carpal translocation after scaphoid volar plate fixation with pedicled vascularized bone graft in scaphoid waist nonunions with humpback deformity.

Methods: A retrospective cohort study of individuals with recalcitrant scaphoid fracture nonunion treated with volar scaphoid plating and vascularized bone graft was analyzed. All patients had radiographs with the wrist at neutral with clinical follow-up of at least 3 months after surgery. Ulnar subluxation of the carpus was assessed by the change in lunate uncovering and carpal-radial distance before and after surgery.

Results: Seventeen patients were included for analysis. Average age was 26 years with an average follow-up interval of 11.0 months. After surgery, 16 patients (94.1%) had fracture union. Between preoperative and initial postoperative imaging, there was an increase in lunate uncovering (mean difference: 8.8%; 95% confidence interval, 4.6% to 13.1%) and carpal-radial distance (mean difference: 3.3% ulnar shift; 95% confidence interval, 1.1% to 5.4%). After surgery, there was minimal change in lunate uncovering and carpal-radial distance from immediately after surgery to final follow-up.

Conclusions: Preoperative lunate uncovering was lower than normal values, suggesting an abnormal radial shift of the carpus with a collapsed scaphoid. Postoperative lunate uncovering was similar to normal values, reflecting an ulnar shift of the carpus after operative intervention.

Type Of Study/level Of Evidence: Therapeutic IV.