Scarf Osteotomy

Technique

 

A.  Longitudinal Cut

- plantar proximal / dorsal distally

- ends up being parallel to sole

- leave strong plantar portion of head to prevent dorsiflexion

- mark centre of head

- distally to a point 2mm prox and 3mm above the centre of the head

 

B.  Transverse cuts

- plantar proximal / dorsal distal

- angle of 45o with the long cut

- directed slightly proximal (10-15o) to aid displacement

 

Displacement

 

A. Transverse plane

- Primary direction of displacement

- can be up to ¾ of the surface as the strong lateral strut is preserved

- lateral rotation should be avoided as it increases the DMAA

- medial rotation can be used (to improve DMAA) but limits the amount of lateral displacement

 

B. Frontal plane

-  Lowering of the 1st MT head is achieved via the obliquity of the transverse cut

-  It will act to relieve metatarsalgia

 

C. Sagittal plane

- Lengthening can be done but tends to increase soft tissue tension and lead to stiffness

- shortening can be readily achieved by

- increasing the obliquity of the transverse cuts (max shortening 3mm)

- resecting ends of prox  / distal fragments (doesn’t elevate head as II to sole)

 

Fixation

 

Cannulated screws over K wires

 

A. Distal

- start lateral where the bone is string and allows medial resection

- aim obliquely into the MT head

- screw to end 2mm prox to cartilage

 

B. Proximal

- important to respect the lateral part of the fragment to avoid fracture

- aim transverse from dorso-medial to plantar-lateral

 

The corner is then taken off the proximal fragment 

- rounded with rongeurs where bunion has been sliced off