A simple technique to achieve parallel transverse cuts in the scarf osteotomy

The scarf osteotomy is a reliable operation to correct moderate to severe deformity in hallux valgus.¹ The proximal and distal transverse osteotomies must be parallel to each other to allow lateral displacement of the distal plantar fragment while also maximising stability.^2,3 Inserting the end of the metallic scarf ruler into the distal transverse osteotomy acts as a parallel guide to aid the surgeon in achieving a parallel proximal transverse cut.

After marking out the Z scarf osteotomy on the first metatarsal (Fig 1), complete the horizontal cut with the micro-oscillating saw. Make the distal transverse osteotomy (Fig 2) and insert the metallic scarf ruler (Fig 3) into the cut (Figs 4). The long medially protruding edge of the ruler will act as a guide to confirm that the proposed proximal transverse osteotomy is parallel to the completed distal osteotomy. Place the micro-oscillating saw against the medial metatarsal cortex and orientate the blade so that it is parallel to that of the ruler edge (Fig 5). Perform the osteotomy, checking regularly that the blade is parallel to the ruler edge (Fig 6). Once complete, remove the ruler and displace the distal plantar fragment laterally as required for optimal correction. Stabilise with two K-wires. Complete the rest of the procedure as routine.

The scarf osteotomy is a technically demanding procedure with a steep learning curve.⁴ This technique will increase the surgeon’s confidence and reliability of making parallel transverse cuts, particularly when at the bottom of the learning curve.