# Proximal Olecranon Free Flap for Cystic Scaphoid Nonunion: An Anatomical Feasibility Study

## TL;DR

This study explores using a bone flap from the elbow to treat wrist bone nonunion, showing it is anatomically feasible.

## Contribution

The study introduces the proximal olecranon as a new donor site for vascularized bone grafts in scaphoid nonunion.

## Key findings

- The posterior ulnar recurrent artery was present in all specimens, supporting flap viability.
- The median pedicle length was 65 mm, with good to moderate bone quality harvested.
- The shortest distance from the scaphoid to the radial artery was 10 mm, indicating grafting may not be needed.

## Abstract

The treatment of scaphoid nonunion is challenging, with one approach aiming to provide vascularized bone to encourage union. While the iliac crest and medial femoral condyle are well-described donor sites for osseous flaps, they require violation of a separate limb and confer particular donor site morbidities. We investigate the viability of using a proximal olecranon osseous free flap in the setting of scaphoid nonunion.

Ten proximal olecranon free flaps were harvested in cadaveric specimens, and the length of the pedicle, diameter of the pedicle, number of perforators and quality of bone graft harvested were recorded. Furthermore, a volar approach to the scaphoid was performed, and the shortest distance from the scaphoid to the radial artery noted, to determine whether utilization of the olecranon free flap was possible without grafting.

The posterior ulnar recurrent artery [PURA] was present in all specimens. The median pedicle length from take-off of the PURA to the olecranon flap was 65 (62.2-71.0) mm. The number of visible periosteal perforators varied between 1 and 2 per specimen. The median diameter of the main perforator before dividing into subperiosteal branches was 2 (2.1-2.5) mm. The quality of the bone graft harvested was mainly assessed as good (n = 5) or moderate (n = 4). The mean shortest distance from scaphoid to radial artery was 10 mm.

The olecranon free flap is a suitable alternative source of vascularized bone for scaphoid nonunion.