Restoring The Metatarsal Parabola With The Weil Osteotomy
Step-By-Step Pointers On The Weil Osteotomy
You may perform the operative procedure while the patient is under general anesthesia or intravenous sedation, using an ankle tourniquet for hemostasis. Make a linear skin incision approximately 3.5 cm long over the distal third of the second metatarsal. Typically, I limit the distal aspect of incision to the base of the proximal phalanx. This will reduce the chance of scar formation that can contribute to dorsal contracture and limits digital swelling. A lazy-S incision is also an acceptable approach and can be beneficial for an adjacent joint capsulotomy or when extending the incision into the second interspace for shortening of the second and third metatarsals.
Once the joint capsule is exposed, identify the base of the proximal phalanx as a reference for the distal aspect of the capsular incision. Once the extensor tendons are retracted laterally, incise the periosteum and capsule while dorsiflexing the toe to protect the articular cartilage. Releasing the collateral ligaments facilitates dorsal displacement and exposure of the metatarsal head.3 You may want to use a McGlamry elevator to further free up the plantar second metatarsal head, especially in the presence of a longstanding submetatarsal phalangeal joint callus.6
Perform the osteotomy with a 10-mm saw blade approximately 0.4 mm thick (Hall Zimmer 5023-138 blade) for a bicortical osteotomy, starting at the dorsal edge of the distal articular cartilage. The plane of the osteotomy is ideal when parallel to the weightbearing surface of the ground.1 This orientation maximizes shortening with minimal dorsal or plantar displacement. If you desire additional elevation, leave the distal cortex intact while passing the sagittal saw blade through for an additional 0.4 mm of elevation, and then transect the proximal plantar cortex. Then you can transpose the metatarsal head proximally with dorsal elevation. You can estimate the amount of shortening by the amount of dorsal cortex overlap at the metatarsal head area, which you will remove with a bone cutting forceps after placing rigid internal fixation. Temporary fixation with a 1.1-mm K-wire is sufficient and should serve as the placement site for the second screw.
After placing the initial screw, a second screw will replace the temporary fixation K-wire. In a small metatarsal, a 1.5-mm screw can be substituted. Both screws are oriented from dorsal proximal to distal plantar. You may prefer using the small diameter cannulated screw where the temporary fixation will serve as the guide wire. You can use a freer elevator to palpate the K-wire prior to measuring to determine proper length.
Using two-pin temporary fixation also helps limit the torque of the screw during fixation to prevent rotary movement of the metatarsal head. You can maintain compression at the osteotomy using a phalangeal clamp to prevent distraction of the osteotomy while placing the fixation. It is essential that screw length is appropriate since a long screw can lead to localized inflammation and plantar pressure irritation requiring early screw removal. Use fluoroscopic imaging intraoperatively to monitor joint position and screw placement.
Perform standard wound closure after placing fixation. Apply compressive dressings with a dorsal betadine splint in order to maintain a plantar grade second digit for two to three weeks. This helps prevent dorsal contracture of the toe. Ambulation is allowed via partial weightbearing in a surgical shoe for three weeks with cane or crutch assistance.
What About Ancillary Procedures?
Combined procedures may include hammertoe correction with a sagittal plane contracture requiring arthroplasty correction. Decreased flexor-extensor tension balancing may require extensor lengthening or flexor tendon transfers. If the patient has a crossover toe deformity, you can combine lateral translation of the metatarsal head with the proximal displacement of the osteotomy in combination with the hammertoe correction. Post-op recovery should then follow the standard of care for the more involved procedure.