- Percutaneous to the navicular
The percutaneous approach to the navicular can be used for screw fixation in non-displaced or minimally displaced simple/non-comminuted fractures (i.e. mid-body stress fractures).
The dorsomedial approach to the navicular is made between the tibialis anterior tendon and extensor hallucis longus (EHL) tendon. The approach should be made straight down from skin to periosteum without raising flaps or any unnecessary dissection.
The neurovascular structures (dorsalis pedis artery) should be lateral to the EHL, but any small branches should be avoided, or cauterized.
The incision uses the interval between the tibialis anterior and the EHL, roughly directly over the fracture.
Two small stab incisions can be made dorsomedial and dorsolateral to allow for insertion of the pointed reduction clamps.
The tips of the pointed clamp are then applied through the stab incisions directly to the bone. Make sure that you do not overcompress and that you apply the clamp directly to the middle of the bone. Overcompression may result in alteration of the normal concavity of the navicular.
There is also a risk of malreduction, if the tips of the reduction clamp are positioned too far proximally.
The stab incision medially would actually be part of the medial utility incision in its placement and if necessary could be enlarged. The lag screw would then be applied through this incision whatever its length. Often provisional K-wire fixation is necessary since the position of the tip of the reduction clamp is exactly where you want to insert the lag screw.
The fracture can be located using image intensification. The fracture site can then be directly entered. In the case of non-healing stress fracture, the surfaces can be freshened by curetting, or drilling. If a small cavity exists, this can be filled with bone graft.
In general wounds must be closed without any tension on the skin edges. Since there is not much soft tissue in the midfoot, the deep layer closure may consist of closing the capsule/periosteum in order to take off tension from the overlying skin. The next layer is the subcutaneous layer which is loosely reapproximated using 2-0 vicryl (absorbable braided). The skin is closed without tension using an appropriate running everting suture (absorbable) or staples (less reactive but can last longer). In the case of multiple adjacent incisions (double dorsal Lisfranc approach) nylon can be used. The knots are placed outside the skin bridge.