Central Rays: V Osteotomy, DFWO, Condylectomy
William D. Fishco
Jeffrey S. Boberg
Pressure-induced metatarsalgia is a common painful condition in the plantar forefoot. If present with concomitant hyperkeratotic lesion, it will typically require surgical intervention for resolution. Metatarsalgia without callus is usually an acute inflammatory process of the lesser metatarsophalangeal joint (MTPJ). This variant will more likely respond to nonoperative care.
DIAGNOSIS AND FUNCTIONAL ANATOMY
Examination should involve palpation of each of the MTPJs, the intermetatarsal spaces, and dorsal metatarsal shafts. Pain on the dorsal metatarsal would be typical in stress fracture, periostitis, capsulitis, or tendinitis. Pain in the intermetatarsal space is consistent with neuroma or intermetatarsal bursitis.
It is important when evaluating the metatarsal heads to differentiate plantar plate pain from a prominent plantar metatarsal head. The plantar plate is palpated distal to the metatarsal head, at the level of the digital sulcus. Pressure occurs at the toe off phase of the gait cycle when all weight is placed on the distal aspect of the metatarsal head. There is decreasing direct pressure and increased torsional forces. This produces a mild diffuse callus just distal to the metatarsal head or no noticeable callus. Pain in the plantar plate represents an acute inflammatory process of the MTPJ.
The metatarsal heads are more proximal and can easily be identified by dorsiflexion of the digits while palpating the plantar ball of the foot. In this location, the pressure peaks during the stance phase of the gait cycle. Pressure from the plantar condyles will typically produce a focal hyperkeratosis (Fig. 22.1).
Metatarsalgia is often secondary to other underlying structural or biomechanical abnormalities. In a Morton foot type, the first ray is short, thereby having a relatively long second ray. Mechanical disorders of the first ray, such as hallux valgus and hallux limitus, can contribute to lesser metatarsal overload. Any previous foot surgery that alters the structure or mechanics of the foot can lead to lesser metatarsal overload.
Digital deformities often play a significant role in metatarsalgia. Rigid hammertoes with contracture of the MTPJ cause excessive retrograde pressures to the metatarsal heads. Once assessed, these abnormalities may require attention. However, addressing these underlying etiologies may not be sufficient or necessary to correct metatarsalgia.
Lack of fat pad in the elderly or in the rheumatoid patient can also be a cause of metatarsalgia. Blood work assessing for rheumatic conditions can be done to rule out a systemic cause of metatarsalgia if there are concomitant symptoms such as joint pain and swelling in the hands or other joints.
Plain film radiographs can aid in determining if there is structural abnormality of the metatarsal(s) that could cause excessive pressures to the forefoot. The anteroposterior radiograph is viewed to assess metatarsal length or parabola. The generally accepted normal metatarsal parabola is the second metatarsal slightly longer than the first, with the first and third about the same length, and gradual decreasing length of the third, fourth, and fifth. There is no one accepted formula for determining appropriate metatarsal length pattern. Clinical judgment is as important as radiographic interpretation.
The oblique and sesamoid axial view radiographs can help determine if there is any sagittal plane abnormality (Fig. 22.2). In the oblique view, the central metatarsals should be parallel to one another. On the sesamoid axial view, the metatarsals should be aligned on the supporting surface and sagittal plane discrepancies are noted. The lateral view radiograph is most helpful in understanding the position of the first ray. First ray elevatus can be determined by comparing the dorsal cortices of the first and second ray.
Conservative treatments for metatarsalgia include functional as well as accommodative devices. Avoidance of flimsy shoes and barefoot walking is recommended. A rocker sole, metatarsal bar, or a shoe with a rigid sole all can provide relief by reducing heel rise during gait.
SURGICAL CRITERIA, SELECTION OF PROCEDURE, AND CONTRAINDICATIONS
Surgery is indicated when conservative measures fail. Although it is important to ascertain concomitant pathologies that contribute to metatarsalgia, metatarsal osteotomies are often the procedures of choice. Hallux valgus and hammertoe correction have not been demonstrated to reliably correct metatarsalgia. Surgery of the lesser metatarsals for metatarsalgia falls into two basic categories: osteotomy or condylectomy. An osteotomy is performed to either alter the length or sagittal plane position of the metatarsal. If the metatarsal is relatively low in the sagittal plane, then it is elevated with an osteotomy. If the metatarsal is excessively long, then it is shortened. A condylectomy is considered in a patient that may have osteopenic bone or is not a good candidate for osteotomy and internal fixation. When there is dislocation of the toe at the MTPJ, an intra-articular decompression osteotomy such as the Weil osteotomy may be a better choice to relocate the joint versus an extra-articular osteotomy like a chevron or tilt-up technique.
REVIEW OF THE LITERATURE
There is a paucity of long-term outcomes studies on lesser metatarsal surgery for central ray metatarsalgia. Most authors today recommend a procedure that will provide predictable alteration of metatarsal length or position with osteotomies that are amenable to rigid internal fixation. Kitaoka and Patzer, in 1998, reported on the chevron osteotomy in 21 feet, and they observed good results in 16 feet, fair in 2 feet, and poor in 3 feet. Four patients had persistent painful callus after surgery. Mean follow-up in this group was 4 years (2 to 7 years) (1). In 2000, Vandeputte et al reported research on the Weil osteotomy and its effect on callus resolution and pedographic changes after surgery. In this study, 59 metatarsals from 32 patients were evaluated. Eighty-six percent of the patients were deemed to have had excellent or good results. Pre- and postoperative pedographic measurements were analyzed, which showed a statistically significant decrease in load under the metatarsal head postoperatively. Seventy-five percent of the metatarsals resulted in complete resolution of callus and partial resolution in 20% (2). O’Kane and Kilmartin reported on 40 Weil osteotomies for central metatarsalgia in 2002. In this study, the second and third metatarsals were shortened in 20 feet. At 18 months, 85% of the patients were completely satisfied, 1 patient was satisfied, 1 patient was satisfied with reservations, and 1 patient was dissatisfied. One patient had complete recurrence of symptoms, 8 out of the 40 toes were floating, 4 had stiff MTPJs, and a transfer callus was noted in one patient (3). Hofstaetter et al in 2005 published a prospective study on 25 feet that underwent Weil osteotomies for metatarsalgia. Patients were evaluated at 1 and 7 years. Good to excellent results were obtained in 84% after 1 year and 88% after 7 years. The procedure significantly reduced pain and diminished associated callus. Common side effects included a floating toe and stiff MTPJ (4).