Rigid, pre-contoured plate results in 94% MTP-1 arthrodesis rate

A retrospective review identified few failures at 29 months postop, average, among complex cases treated with the titanium plate.

Investigators from Washington reported a 6% failure rate using rigid, pre-contoured plates for first metatarsophalangeal joint fusion in complex cases.

High rates of arthrodesis of this joint from 92% to 100% have been published in the literature, but such foot surgeons as Michael J. Coughlin, MD, reported performing subsequent plate removal in one-third to all of their cases. “No consensus currently exists on which is the best technique,” said Matthew J. Hawkins, MD, a resident at Georgetown University Medical Center, where the study was conducted.

Hawkins presented the findings at the American Orthopaedic Foot and Ankle Society (AOFAS) 21st Annual Summer Meeting. “Rigid pre-contoured plate fixation combined with cup-in-cone bone preparer achieved a 94% fusion rate and statistically significant favorable outcomes,” he said. Researchers identified just two failures.

Hawkins said other investigators were now beginning to report better outcomes, as well, using the same approach, which involved cone and cup reaming, but used a different plate for stabilization.

Retrospective surgical review

Investigators retrospectively followed 29 patients who underwent 32 cup-in-cone first metatarsophalangeal (MTP) fusions through an average 29 months postop (range, five to 56 months). The 24 women and five men were treated for late hallux valgus (13), hallux rigidus (9), failed bunion surgery (5), rheumatoid arthritis (4) and posttraumatic arthrosis (1). Seventeen patients underwent previous first MTP joint procedures.

During the operations, surgeons made a dorsal longitudinal incision centered over the first MTP joint, extending them to medially to the extensor hallux longus tendon and then retracted the tendon laterally. They next plantar flexed the proximal phalanx and exposed the joint’s articular surfaces, preparing them with cup and cone reamers. To stimulate subchondral bleeding, surgeons drilled the surfaces with 0.062-mm Kirschner wires.

They then positioned both sides of the joint and provisionally stabilized them with obliquely directed Kirschner wires. Surgeons used simulated weightbearing with a flat plate to confirm the joint was properly positioned and implanted the titanium plate (Acumed LLC; Hillsboro, Ore.). They fixed it dorsally with 4-mm cancellous screws.

High satisfaction ratings

Investigators used the AOFAS score and its pain subscale, as well as patient satisfaction, to rate the outcomes. “Ninety-four percent of patients achieved clinical and radiographic union. Ninety-four percent were satisfied with their cosmetic appearance postoperative and 90% overall were satisfied and would undergo [the surgery] again for the same problem,” Hawkins said.

Preoperative AOFAS scores improved significantly from 38 at preop to 71 at postop (P<.001) and pain scores improved from 11.6 at preop to 34.8 at postop. Joint alignment also improved. Hallux valgus angles decreased from 25.2º at preop to 12.8º postoperatively. At final follow-up, first metatyarsophalangeal dorsiflexion inclination angles averaged 6.2º.

The two failed cases occurred in two patients who developed infections during prior foot surgery. A 61-year-old woman said she was satisfied with her result, but experienced a stable pseudarthrosis and screw breakage. A bilateral case failed due to infection that required plate removal.

“Further studies are needed to compare fixation methods in a prospective randomized fashion in order to elucidate the ideal technique.”

For more information:
Hawkins MJ, Christoforetti J, Barimany R, et al. First metatarsal joint fusion with pre-contoured plate fixation: A promising new technique. Presented at the American Orthopaedic Foot and Ankle Society 21st Annual Summer Meeting. July 14-17, 2005. Boston.