Surgical Procedure
Curved lateral incision
Create surface area for osteotomy. Be aware of sural nerve and peroneal tendons.
Create room for Hohman retractors by using curved pereosteal elevator.
Place Hohman retractors
Place positioning device with an angle of 45 degrees.
Dismount removable part
Create osteotomy and use the positioning device as sawguide. Be aware of the Achilles tendon and insertion of the plantar fascia
Remove sawguide and medialize posterior part of the calcaneus with use of a large diameter chisel
Insert 2 K-wires in the pinholes and mount the correct plate including 2 drillguides over the K-wires
Remove 1 K-wire and drill to opposite cortex. Measure length and drill thru the opposite cortex
Apply locking screws of appropriate length.
Maintain medial shift position by pressing the drill guides which are mounted on the plate. Measure length after drilling. 30-40 mm is usually sufficient
Apply lagscrew of appropriate length. This screw provides: compression of the osteotomy, secures correct displacement and provides compression of opposite cortex by means of the sliding mechanism
Apply the last 2 locking screws
Pearls & Pitfalls
Pearls
Pay extra attention to angle of the osteotomy. This should be performed in an angle of 33° to 45° relative to the plantar surface of the foot.
It is important to know if one is lateralizing or medializing the posterior fragment. In case of lateralizing the pins of the sawing jig should be facing towards the anterior part of the calcaneus. When medializing the fragment, the pins of the sawing jig should be facing towards the posterior fragment of the calcaneus.
Pitfalls
It is important to dissect the subcutaneous tissue sufficient of the calcaneus, so that the sawing jig will not be placed to distal to the posterior side of the calcaneus.
Make sure to saw unto the overlying cortex of the calcaneus and to tap this before sawing.