Simple method of exacting a desired parabola for pan-metatarsal head resection

Simple Method of Exacting a Desired Parabola for Pan-metatarsal Head Resection Richard O. Jones, DPM, MPH, Darren Payne, DPM, and Brent A. Clark, DPM When performing the pan-metatarsal head resection for rheumatoid arthritis forefoot reconstruction, estimating the lesser metatarsal parabola can be a challenge. Many times the bases of the proximal phalanx are subluxed, dislocated, or unreducible, and may sit on top of the lesser metatarsals (Fig. 1). This can often make it difficult to determine the level of metatarsal head resection. It was not uncommon to resect too much bone (Fig. 2) or leave one or more of the metatarsals long or short (Fig. 3). The technique that we have developed makes cutting the parabola more predictable. The authors' preferred technique employs three longitudinal dorsal linear skin incisions. The medial incision is to address the first metatarsophalangeal joint. The one between the second and third metatarsals and the other between the fourth and fifth metatarsals address the respective adjacent metatarsal heads. Dissection is carried down to the lesser metatarsal necks and a O.045-inch Kwire is inserted from dorsal to plantar through each of the metatarsal necks, starting with the second and progressing to the fifth (Figs 4 and 5). The parabola is first estimated as one proceeds laterally and then confirmed by intraoperative C-arm (mini-fluoroscopy) (Fig. 6) or by an anteriorposterior radiograph. If the K-wires do not reflect the desired parabola, the wires are adjusted until the desired parabola is achieved. All of the pins are removed and the osteotomy cuts are made where the pins left a hole in the metatarsal. Scoring the metatarsal with a marking pen at the correct hole prior to osteotomy will prevent mistakes in cases where the pins were adjusted and there was more than one hole in the metatarsal) (Fig. 7). This method has reduced our operating time significantly,

From the Department of Orthopedics, Podiatry Division, Madigan Army Medical Center, Fort Lewis, WA, and Veterans Hospital, Puget Sound Health Care System, American Lake Division, Tacoma, WA. Address correspondence to: Richard O. Jones, DPM, MPH, P.O. Box 98658, Tacoma, WA 98498. E-mail: [email protected]. The Journal of Foot & Ankle Surgery 1067-2516/02/4105-0342$4.00/0 Copyright © 2002 by the American College of Foot and Ankle Surgeons

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FIGURE 1 Dorsal plantar radiograph of patient with rheumatoid arthritis demonstrating proximal retraction of the phalangeal bases on the metatarsal heads.

eliminates the guesswork, and exacts a desired metatarsal parabola (Fig. 8).

FIGURE 2 Dorsal plantar radiograph showing parabola with excessive metatarsal head resection.

FIGURE 4

FIGURE 3 Radiograph showing not enough bone removed from third metatarsal.

Clinical photograph showing intraoperative placement of K-wires.

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FIGURE 5

Saw bone model depicting placement of K-wires.

FIGURE 7 Saw bone model showing how lesser metatarsals are scored with marking pen at the level of the proper K-wire tract.

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Intraoperative fluoroscopy with K-wires to determine parabola.

FIGURE 6

FIGURE 8

Postoperative AP radiograph show ing proper level of resection using described method.

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