How To Address High Intermetatarsal Angles In Bunion Surgery
Starting at the midline of the medial flare of the first metatarsal about 2 cm distal to the tarsometarsal, direct the screw to the proximal lateral corner of the second cuneiform. One can visualize this on fluoroscopy and place the screw in typical lag fashion. The typical screw length is in the 34 to 42 mm range. While maintaining the guide wire in the screw, one can see where to avoid placing the locking neutralization plate. We routinely use locking plate technology in this procedure for added stability and earlier weightbearing.10-14 After placing the locked plate, we then remove the tenaculum and assess the intermetatarsal correction on fluoroscopy. At this time, if the metatarsal is not reduced over the sesamoids, one can manually assess the relocation of the sesamoids with medial capsule traction.
What if the intermetatarsal angle is not reduced after removing the tenaculum? First, check the interfragmentary screw placement. Make certain you are capturing the first metatarsal and have not fractured the base of the metatarsal. Proceed to utilize fluoroscopy to ensure you have placed the plate appropriately across the joint. It is easy to mistakenly place the plate too distal and lateral, and one has to correct this if the distal screws are not purchasing bone.
If there is proper fixation placement and the reduction is still not adequate, we often utilize an intermetatarsal lag screw from the base of the first metatarsal into the base of the second metatarsal. Take care not to overtighten this screw for it can easily create a hallux varus. After obtaining tarsometatarsal reduction and when the sesamoids are easily reducible, one may still need to perform an Akin procedure to gain final reduction of the hallux on the metatarsal. This is often the case with severe deformities.
Key Insights On Closure And Postoperative Protocol
Closure then begins with absorbable sutures on the medial first metatarsophalangeal capsule. Close all incisions in layers with absorbable sutures and skin with subcuticular sutures. Then use sterile dressings and place the patient in a non-weightbearing splint.
Our preferred postoperative protocol for Lapidus arthrodesis has changed over the years as more evidence has emerged for early weightbearing.14 Patients wear a non-weightbearing splint until the first postoperative visit at six days and subsequently wear a weightbearing tall fracture boot for four to six weeks. One should then reassess the patient and transition him or her to a shoe over the next four weeks.
When it comes to severe deformity correction, we offer the following take-home points.
* Assess more than the intermetatarsal angle.
* Perform an adequate distal soft tissue procedure.
* Use a tenaculum and windlass mechanism to maintain reduction.
* Our preferred method of fixation is a combination of a first metatarsal-second cuneiform lag screw and medial neutralization (locked) plate.
* Do not remove the clamp until the plate is in place.
Severe bunion deformities with an associated high intermetatarsal angle are challenging and surgeons should not take them lightly. Multiple procedures are often necessary to reduce the deformity fully and maintain correction.
Dr. McAlister is a Fellow of the Orthopedic Foot and Ankle Center in Westerville, Ohio.
Dr. Hyer is a Fellow of the American College of Foot and Ankle Surgeons, and serves on its Board of Directors. He is the Fellowship Co-Director of the Orthopedic Foot and Ankle Center in Westerville, Ohio.