Key Insights On Performing A Revisional Positional First MPJ Arthrodesis

Lawrence A. DiDomenico, DPM, FACFAS, and Zachary M. Thomas, DPM

   We decided to perform a revisional positional arthrodesis of the first MTP using autogenous bone graft. After ensuring supine positioning of the patient on the operating room table, we applied an ipsilateral thigh tourniquet to the right mid-thigh. Making the incision over the previous incisions of the first MTP, we carried dissection down to bone and created full thickness flaps. Reflecting the flaps medially and laterally exposed the mal-union. Utilizing fluoroscopic guidance, we identified the previous arthrodesis site and used a power saw to create an osteotomy of the near cortex. We took down the remainder of the malunion site with an osteotome and mallet. Inserting a laminar spreader brought the great toe out to length and an anatomic position. We spent a significant amount of time preparing the recipient site for grafting. A 2.0 drill, pics and curettes created bleeding bone.

   We proceeded to focus on the lateral wall of the calcaneus where we made an oblique incision posteriorly and inferiorly to the sural nerve as well as the peroneal tendons. We carried this incision down to the periosteum and reflected the tissues, exposing that lateral wall of the calcaneus.

   Subsequently, we shifted our attention to ensuring appropriate anatomic positioning of the first MTP. We measured for the needed graft size and used four 0.062 K–wires to create an appropriately sized harvest site in the calcaneus. Employing a power saw, osteotomes and a mallet, we harvested a tricortical cancellous bone graft from the lateral mid-portion of the calcaneus. Then we backfilled the host site with allogenic bone graft.

   We fashioned the graft to fit the recipient site and tamped it into place. Subsequently, we inserted a 3.5 mm fully threaded positional screw from the first metatarsal (just behind the condyle) through the graft and into the distal lateral aspect of the great toe, ensuring that the screw would catch the far cortex. Then we inserted a six-hole plate consisting of locking and non-locking screws into the dorsal aspect of the first metatarsal, the autogenous bone graft and the great toe.

   Clinical and fluoroscopic examination confirmed the desired anatomic alignment. We subsequently fixated the construct with a combination of locking and non-locking screws. Postoperatively, the patient bore partial weight in a fracture boot. There was good consolidation postoperatively and we were able to achieve a successful arthrodesis with the first MTP in good anatomic alignment.

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