CHAPTER 8 Hallux Rigidus

OVERVIEW OF SURGERY AND DECISION MAKING

Surgical correction of hallux rigidus gives fairly predictable results, and patient acceptance and aesthetic and functional outcomes should be good. Many surgical alternatives are available to choose from, all based on considerations of the underlying anatomy, the pathologic changes, and the severity of the arthritis. Patient needs for activities and shoe wear will also influence the decision making for the type of surgery. In my own practice, the cheilectomy, with or without an osteotomy at the base of the proximal phalanx (the Moberg procedure), is the most predictable operation for correction of hallux rigidus. For management of the more severe grades of arthritis, although I perform arthrodesis frequently, I have obtained excellent results with interposition arthroplasty. Despite efforts with various implants, I have achieved less than desirable results with any type of implant arthroplasty. Arthrodesis continues to be a mainstay of treatment in the management of severe arthritis associated with deformity or in cases in which other salvage procedures in the forefoot need to be performed simultaneously.

In planning surgery, the range of motion of the metatarsophalangeal (MP) and interphalangeal (IP) joints of the hallux is important. I examine the foot while the patient is seated, as well as standing, because additional contracture, particularly of the flexor hallucis brevis, may become evident with standing. The ability of the patient to passively dorsiflex the hallux while standing also is noted.

Occasionally, osteotomy of the first metatarsal is advantageous. Elevation of the first metatarsal may not have a significant role in the pathogenesis of hallux rigidus (Figure 8-1). Nevertheless, a most definite correlation exists between metatarsus elevatus and severe grades of hallux rigidus. In such cases, however, the elevation of the first metatarsal may be secondary to the severe contracture of the intrinsics and retraction of the volar plate, rather than a primary condition. Although osteotomy may be required for correction of primary or congenital metatarsus elevatus, one has to be careful with the notion that an osteotomy of the metatarsal is routinely necessary to alleviate dorsal impingement from hallux rigidus. Clearly, certain deformities will benefit from an osteotomy—for example, a long first metatarsal or one that is abnormally elevated. Other deformities require more care with decision making about the corrective procedure. Regardless of the extent of its deformity, an arthrodesis of the MP joint will not be successful in a patient with a fixed elevated first metatarsal and hyperextension of the hallux IP joint. The result will be only to create additional load on the IP joint, ultimately causing pain with further subluxation and extension. The hallux will have to be cocked up significantly to position the arthrodesis in order to unload it from the plantar weight-bearing surface. This cocked-up position in turn will cause rubbing of the tip of the hallux on the shoe. Note that in Figure 8-2, the patient had already undergone an unsuccessful cheilectomy. In the standing position, the hallux is rigidly on the ground and the IP joint is hyperextended. Further attempts at passive dorsiflexion of the joint only worsened the IP hyperextension.

Figure 8-1 A, Although the first metatarsal is elevated, a metatarsal osteotomy was judged not to be of any potential benefit to the patient. The metatarsophalangeal (MP) joint was quite mobile, as was the first metatarsal. B, A standard cheilectomy was performed, with good results, including improved motion at the MP joint after surgery.

Figure 8-2 Elevation of the first metatarsal in a patient who already underwent an unsuccessful cheilectomy. A, With the patient standing, the tip of the hallux is noted to be extended. B, On pushing up further under the hallux, dorsiflexion of the metatarsophalangeal joint does not occur; only further extension of the interphalangeal joint is seen.

What is the condition of the sesamoids? Is there arthritis between the sesamoids and the metatarsal head? It is useful to perform a compression test or “grind test” by pressing under the sesamoids while attempting to dorsiflex the hallux. If such testing causes pain, even if radiographic degenerative changes are minimal, a cheilectomy may not work. A long metatarsal with the hallux in slight fixed flexion is associated with scarring and tightening of the sesamoid complex, and a cheilectomy will not work here either. In this latter situation, I would prefer to slightly shorten the metatarsal to take the pressure off the sesamoid apparatus and improve dorsiflexion.

CHEILECTOMY

Historically, cheilectomy has been used for patients with early- or intermediate-stage arthritis. An increasing trend over the past few years, however, has been to extend the indications for a cheilectomy to more advanced forms of arthritis. In clinical practice I have encountered many a patient who returns some years after a successful cheilectomy for treatment of hallux rigidus on the opposite foot. Radiographs of both feet typically demonstrate that the operated asymptomatic foot looks worse than the symptomatic foot. This finding may have something to do with denervation of the joint, but certainly, it is common enough that a cheilectomy may be performed for more advanced arthritis of the MP joint.

An incision is made dorsomedial to the extensor hallucis longus (EHL) tendon extending for 3 cm over the MP joint (Figure 8-3). The dorsal medial cutaneous branch of the superficial peroneal nerve must be avoided and retracted laterally. The capsule is incised, preserving a cuff of at least 5 mm medially for later closure. The capsule and periosteum are reflected off the metatarsal neck to expose the hypertrophic osteophytes dorsally. It can be difficult to expose the joint in the presence of large osteophytes, but the entire dorsal head must be exposed. Adequate exposure can be a problem in the foot with a large medial eminence as well as hallux rigidus, in which case the exostectomy will need to be performed with preservation of as much of the capsule medially as possible for closure. Alternatively, a medial incision with a medial capsulotomy can be used to approach cheilectomy in the presence of hallux valgus.

Figure 8-3 The dorsomedial incision for cheilectomy.

I prefer to use a chisel to remove the dorsal apical surface of the metatarsal head, because this gives me better control than that possible with an osteotome or a saw. The chisel is placed in the center of the metatarsal head, and one third of the dorsal surface of the metatarsal head is removed (Figure 8-4). At this point in the procedure, it always seems that too much of the metatarsal head is being removed, but the amount of bone that should be removed is almost always underestimated. When the head is viewed from above, one third of its volume seems like a large amount of bone to resect until an intraoperative radiograph is obtained, whereupon how little has actually been removed becomes evident. The ostectomy must be performed from distal to proximal, with removal of the dorsal osteophytes, and then the medial and lateral margins of the metatarsal head are contoured. If cysts are present in the metatarsal head, the ostectomy can be performed just dorsal to the erosion, or the head drilled with a Kirschner wire (K-wire), which may improve the fibrocartilaginous surface (Figure 8-5). Rounding off of the metatarsal head is performed using a rongeur and chisel, but care is taken not to dissect too far proximally. If the marginal osteophytes need to be removed, this can be done with the chisel, but again, it is essential not to go too far proximally on the lateral aspect of the head, which can result in avascular necrosis. The capsular attachment to the medial aspect of the first metatarsal head should be left intact. Range of dorsiflexion of the MP joint should be at least 65 degrees after the cheilectomy.