OVERVIEW

It is important to distinguish between the procedure as originally described by Paul Lapidus, which included an arthrodesis between the base of the first and second metatarsals, and the modified Lapidus procedure, which stabilizes only the first metatarsocuneiform (MC) joint. The true Lapidus procedure is indicated primarily when significant transverse plane instability is present. This instability may be at the MC joint, or between the medial and middle columns, extending into the interspace between the medial and middle cuneiforms. Generally, I perform the modified Lapidus procedure, with addition of stabilization between the first and second metatarsals only if persistent instability is present after arthrodesis of the MC joint. The indications for the Lapidus bunionectomy therefore include hypermobility and instability of the first metatarsal in either the sagittal or the transverse plane.

Examination for sagittal plane instability or hypermobility is best performed by stabilizing the lateral aspect of the foot and then manipulating the medial column in a dorsal or plantar direction (Figure 3-1). There is obviously a “feel” to this examination, and although objective interobserver reliability may not be achievable among surgeons who examine the foot for instability, each surgeon should establish personal criteria for what is normal and what is abnormal. An important component of this test for increased first ray mobility is to establish that it is only the first metatarsal and not the entire medial column that is mobile. By pushing the lateral column into maximum dorsiflexion and then testing the first ray, a more accurate result will be obtained. Radiographic parameters of instability are helpful but unreliable in planning this operation; however, instability in the transverse plane is easy to document (Figure 3-2).

Figure 3-1 Hypermobility associated with hallux valgus is revealed by moving the first metatarsal in a plantar (A) and then a dorsal (B) direction after firmly stabilizing the lateral column of the foot. There is a “feel” for this maneuver, and all patients with hallux valgus should undergo this test for instability in the sagittal plane. Examination specifically for instability in the transverse plane (between the first and second metatarsals) also is indicated.

Figure 3-2 Transverse plane instability, demonstrated in A and B, is correctable with strapping of the forefoot, as shown in C and D. Radiographs taken with and without the strapping will confirm the presence of such excessive mobility. This is an ideal deformity to correct with the modified Lapidus procedure.

Patients with arthritis of the first or second metatarsal cuneiform joint associated with hallux valgus are best treated with an extended Lapidus procedure to include the metatarsocuneiform joints. Arthritis of the second tarsometatarsal (TMT) joint usually is the result of the instability of the first metatarsal, with hypermobility leading to overload of the second metatarsal and, ultimately, arthritis. Frequently, patients with arthritis of the second metatarsal cuneiform joint have associated arthritis of the first metatarsal cuneiform joint as well, but the Lapidus procedure is indicated nonetheless in the absence of arthritis of the first metatarsal cuneiform joint.

The Lapidus procedure is an important adjunct to the correction of the flatfoot deformity when instability of the first metatarsocuneiform joint is present.

INCISION AND DISSECTION

I used to perform the procedure using three incisions, one for the distal soft tissue release, one for the exostectomy and the capsulorrhaphy, and one for the arthrodesis. I have found that one long dorsal incision is cosmetically preferable, and indeed, the exostectomy can be performed through the same incision or may not be needed at all (Figure 3-3). After the distal soft tissue and adductor release, the incision is extended proximally, lateral to the extensor hallucis longus tendon, without injury to the deep peroneal nerve. In my experience, this single midline incision is more cosmetically acceptable and facilitates exposure of the TMT joint proximally. The exostectomy is not performed at this time, because subtle rotation of the metatarsal may occur after arthrodesis, changing the axis of the exostectomy, and if the arthrodesis is performed correctly, it is often not necessary to do an exostectomy. The extensor hallucis longus tendon is retracted medially, and with subperiosteal dissection, the dorsal surface of the articulation is identified and opened. The key to the joint debridement is restraint, because only the articular cartilage and minimal subchondral bone should be removed.

Figure 3-3 Steps of the modified Lapidus procedure. A, A single incision can be used to perform the adductor release, the tarsometatarsal arthrodesis, and the exostectomy. B, The entire articulation surface, in particular the plantar surface, is debrided. C, The hallux is dorsiflexed, and the metatarsal is pushed into alignment, while a guide pin is introduced to position the reduction of the joint. D, The first screw is inserted from dorsal and proximal to the plantar and distal surfaces. E, Once the arthrodesis was completed, an exostectomy was performed.

Although the first metatarsal is moved laterally during the procedure, such movement is not performed through removal of any wedges of bone, which shortens the metatarsal. Instead, translation and rotation of the metatarsal base are preferable. The ease of this manipulation will depend on the configuration of the articulation, which typically is saddle-shaped and may not be amenable to this translational movement. A smooth laminar spreader is inserted into the TMT articulation, and the joint is distracted to provide visualization of the plantar surface of the first metatarsal. The joint is much deeper than might be expected, and for prevention of a dorsal malunion, the entire joint must be denuded. I prefer to use a chisel instead of a saw blade to denude the articular cartilage, and then I perforate the joint multiple times using a small drill bit down to healthy bleeding subchondral bone on both the metatarsal and cuneiform surfaces (Figure 3-4). The perforation of the joint surfaces probably is the most important component of the procedure, and with this minor change to technique, I have rarely encountered a nonunion over the recent past.

Figure 3-4 A and B, Preoperative radiographs showing an unstable hallux deformity in a 21-year-old patient. Elevation of the first metatarsal is evident on the lateral view (B). C, A 2-mm drill bit was used to perforate the joint surfaces, creating a slurry in the joint. D and E, No transverse plane instability was noted intraoperatively, so only axial screw fixation was used in a modified Lapidus procedure. No exostectomy or capsulorrhaphy was performed.

CORRECTION OF DEFORMITY

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The Modified Ludloff Metatarsal Osteotomy Correction of Flatfoot Deformity in the Child Correction of Lesser Toe Deformity Peroneal Tendon Injury and Repair Subtalar Arthrodesis Arthrodesis of the Hallux Metatarsophalangeal and Interphalangeal Joints

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