Palmar Radiocarpal Artery Vascularized Bone Graft for the Unstable Humpbacked Scaphoid Nonunion With an Avascular Proximal Pole.

PURPOSE: The most challenging scaphoid nonunion is the unstable nonunion with humpbacked collapse coupled with an avascular proximal pole. Dorsal distal radius pedicled vascularized bone grafts (VBGs) are contraindicated in cases of humpback deformity. The free medial femoral condyle VBG is an excellent option but it is an extensive microsurgical procedure with lengthy operative times and dual-limb incisions. In search of a local, volar, vascularized source of bone to treat this challenging subset of scaphoid nonunions, we analyzed our results with a volar distal radius bone graft based on the pedicled palmar radiocarpal artery (PRCA).

METHODS

A prospective cohort of 15 unstable nonunions with avascular proximal pole fragments was treated with the PRCA graft and open reduction internal fixation. Preoperative carpal indices revealed a high degree of instability. All 15 lacked punctate bleeding from the proximal pole. All 15 patients were treated with the PRCA VBG technique and scanned with computed tomography at approximately 6 and 12 weeks to assess for interval healing.

RESULTS

All nonunions healed with an average cross-sectional trabeculation score of 70% at week 6 and 84% at week 12. Sagittal intrascaphoid angles improved from 50° to 27°, radiolunate angle improved from -20° to -7°, scapholunate angle improved from 86° to 64°, and revised carpal height ratio improved from 1.45 to 1.53, indicating correction of the humpback collapse deformity. Patients were observed an average of 22 months to have no sign of further avascular necrosis.

CONCLUSIONS

Pedicled PRCA-VBG successfully addresses the dual needs of the humpbacked scaphoid nonunion with an avascular proximal pole while simultaneously limiting dissection to one limb and avoiding the additional complexities of free tissue transfer.

TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic II.