Lone Star Orthopaedics, Cincinnati, Ohio. t To whom requests for reprints should be addressed at Meth- odist Sports Medicine Center, Department of Research ...
0198-0211/99/2011-0752/0 FOOT & ANKLE INTERNATIONAL Copyright © 1999 by the American Orthopaedic Foot and Ankle Society, Inc.
Technique Tip:
Correction Augmentation and Provisional Fixation in Proximal Metatarsal Osteotomies Using Kirschner Wires James A. Amis, M.D.: and David A. Porter, MD., Ph.D.'] Cincinnati, Ohio, and Indianapolis, Indiana
INTRODUCTION
A proximal first metatarsal osteotomy with a distal soft-tissue procedure and medial metatarsal head eminence resection is a widely accepted surgical approach to treating the patient who has symptomatic hallux valqus.' We have observed that obtaining the desired amount of correction and maintaining alignment during fixation of the osteotomy were sometimes difficult. To augment our correction and to simplify the process of fixation, we now use a Kirschner wire (Kwire) provisional fixation on proximal metatarsal osteotomies. Provisional fixation gives the surgeon a preview of the first metatarsal correction in both the sagittal plane (dorsiflexion/plantarflexion) and the medial lateral plane (valgus/varus). This technique also enables us to see the effect of the osteotomy on the distal toe before placing the definitive fixation in the proximal metatarsal, which is typically a single lag screw. TECHNIQUE
A standard distal soft-tissue procedure and medial eminence resection is performed before addressing the proximal first metatarsal. A dorsal or dorsomedial incision is used, and the first tarsometatarsal joint is identified. A standard proximal crescentric or proximal chevron osteotomy is performed with the most proximal extent being 1 cm from the tarsometatarsal joint. A single 0.062 K-wire is placed in the dorsal half of the proximal fragment, from medial to lateral, perpendicular to the long axis, extending just to the edge of the lateral cortex (Fig. 1). The proximal fragment is then placed into a maximal varus position and into slight dorsiflexion by placing a bone hook along the
Fig. 1. AP view of provisional fixation for proximal first metatarsal osteotomies. Note the bone hook directing the proximal first metatarsal base dorsal and medial (arrow) with 0.062 K-wire placed through the proximal fragment and into cuneiforms. Also note the second K-wire into the distal fragment metaphysis and into the second metatarsal to maintain the corrected first intermetatarsal angle.
lateral aspect of the metatarsal base and displacing the proximal fragment as far medially as possible. Once the proximal fragment is displaced, the K-wire is driven into the second metatarsal and the displace-
* Lone Star Orthopaedics, Cincinnati, Ohio.
t To whom requests for reprints should be addressed at Methodist Sports Medicine Center, Department of Research and Education, 1815 North Capitol Avenue, Suite 560, Indianapolis, IN 46202. 752
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KIRSCHNER WIRES
Foot & Ankle InternationallVol. 20, No. 11/November 1999
ment is maintained until the osteotomy is fixed permanently. The displacement of the proximal fragment can also be obtained by using a small bone hook or by simply using the K-wire as a joystick, as we prefer. The second 0.062 K-wire is then placed into the distal fragment in the plantar half of the first metatarsal, approximately 1 cm distal to the osteotomy site, just across the lateral cortex, from medial to lateral. The wire is not placed into the second metatarsal at that time. The wire is placed percutaneously if a dorsal incision is made or through the incision if a dorsomedial incision is performed. Thus, the K-wire in the proximal fragment is placed dorsally, and the wire in the distal fragment is placed plantarly to prevent the wires from obstructing the placement of the definitive screw. We place the screw from distal dorsal to proximal plantar (Fig. 2). With the proximal fragment now maximally displaced and held with the K-wire, the distal portion of the osteotomy can be rotated around the proximal fragment and the intermetatarsal angle correction can be "dialed in" without having to struggle to maintain the very short fragment in a displaced position. As this is achieved, the first and second metatarsal heads are almost touching and obliteration of the interspace can be confirmed easily. Appropriate plantarflexion of the distal portion can also be dialed in. After satisfactory correction is obtained, the second K-wire is further placed across the first metatarsal into the second metatarsal provisionally fixing the osteotomy site (Fig. 1). Evaluation of the correction and the effect on the metatarsophalangeal joint is then undertaken without concern for losing the correction. We have found the fixation to be secure enough to allow optimal placement of the single 3.5-mm lag screw (Fig. 2). The screw is then placed with relative
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Fig. 3. AP view of provisional fixation for proximal first metatarsal osteotomies. Note the first metatarsal in corrected position with the K-wire provisional fixation and definitive screw fixation. Pins were removed after rigid screw fixation.
ease and better assurance of the optimal alignment (Fig. 3). We use a portable, low-energy fluoroscopy unit to assess our provisional and definitive correction. After satisfactory alignment and definitive fixation have been obtained, we remove the K-wires, close the wound, and dress the foot in the usual fashion. Intraoperative x-rays are obtained if deemed necessary. Fig. 2. Lateral view of provisional fixation for proximal first metatarsal osteotomies. Note the proximal K-wire in the dorsal half of the first metatarsal proximal fragment and the distal K-wire in the metatarsal head. This pin placement allows screw placement distaldorsal to proximal-plantar.
REFERENCE 1. Mann, R.A., and Coughlin, M.J. (eds.): Surgery of the Foot and Ankle, 6th Ed. St. Louis, Mosby, 1993, pp. 167-297.
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