Abstract
Although the term metatarsalgia is generally used to describe pain in the forefoot, it is better suited to describe the location of pain rather than the diagnosis. The etiologies of forefoot pain include Freiberg disease, intractable plantar keratosis, lesser metatarsophalangeal synovitis, stress fracture, Morton (interdigital) neuroma, sesamoid pathology, transfer metatarsalgia (insufficient loading through the first ray), and equinus contracture. These diagnoses are not mutually exclusive, and the physician must carefully consider the entire foot and ankle to appropriately diagnose and treat the patient’s disease process. In some cases, the patient may have fat pad atrophy with relatively prominent metatarsal heads, and an osteotomy may be needed to elevate the head to relieve the pressure. A dorsal wedge osteotomy of the lesser metatarsals is performed for specific conditions of isolated metatarsalgia, when no other identifiable cause is noted.
Key Words
Freiberg, metatarsalgia, gastrocnemius, Maceira, equinus, interposition arthroplasty
Osteotomies for Metatarsalgia
Although the term metatarsalgia is generally used to describe pain in the forefoot, it is better suited to describe the location of pain rather than the diagnosis. The etiologies of forefoot pain include Freiberg disease, intractable plantar keratosis, lesser metatarsophalangeal (MTP) synovitis, stress fracture, Morton (interdigital) neuroma, sesamoid pathology, transfer metatarsalgia (insufficient loading through the first ray), and equinus contracture. These diagnoses are not mutually exclusive, and the physician must carefully consider the entire foot and ankle to appropriately diagnose and treat the patient’s disease process. In some cases, the patient may have fat pad atrophy with relatively prominent metatarsal heads, and an osteotomy may be needed to elevate the head to relieve the pressure. A dorsal wedge osteotomy of the lesser metatarsals is performed for specific conditions of isolated metatarsalgia, when no other identifiable cause is noted. Although alternatives for bony correction of metatarsalgia are available, such as the Weil or Maceira osteotomy, a shortening diaphyseal osteotomy, and a shortening proximal metatarsal osteotomy, each procedure is associated with potential problems. We have found that the Weil osteotomy can be used for correction of isolated metatarsalgia, but results are not very predictable because of the variable position of the metatarsal after osteotomy in the sagittal plane. When performed for specific relief of metatarsalgia, a dorsal wedge osteotomy gives a very predictable result; however, the potential for subsequent “transfer metatarsalgia” must be considered. Although no osteotomy is so precise that transfer of weight can be avoided, the dorsal wedge osteotomy of the metatarsal neck remains a reasonable procedure for correction after a previous fracture, stress fracture, or previous osteotomy of an adjacent metatarsal. With the more proximal metatarsal osteotomy at the base, the result is very unpredictable, and accurate control cannot be achieved.
Gastrocnemius Recession
Patients having an underlying gastrocnemius contracture will have relief from pain in shoes with a 1- to 2-inch heel. The Silfverskiöld test should be used to assess for isolated contracture of the gastrocnemius in all patients. In this test, ankle dorsiflexion is assessed with the knee in full extension and in 90 degrees of flexion ( Fig. 9.1 ). The foot must be locked in subtalar neutral position. Lack of dorsiflexion past neutral is consistent with an equinus contracture. An increase in dorsiflexion with the knee in flexion is indicative of an isolated gastrocnemius contracture. In these patients, although an osteotomy can be performed to elevate the metatarsal head, the risk of transfer metatarsalgia is higher, as a large contributing factor is the gastrocnemius contracture. We feel that in the setting of metatarsalgia without bony abnormality, a gastrocnemius recession is the preferred method of treatment, as this corrects what is felt to be the underlying etiology without creating secondary forefoot deformity. The results with this treatment have noted a high rate of success with some reporting 90% relief of forefoot pain. Care must be taken to limit this procedure to patients with true equinus, as overlengthening can occur and result in chronic weakness and heel pain. Treating this complication is difficult and we have noted some success with Achilles shortening and flexor hallucis longus transfer, however, the patient satisfaction is highly variable as return to presurgical function is not achieved.
The patient is positioned supine with slight external rotation of the affected limb. A posteromedial incision is made at the musculotendinous junction of the gastrocnemius. With dorsiflexion of the affected limb, the contour of the gastrocnemius is noted both visually and with palpation. The incision should be made at the distal aspect of the convexity of the gastrocnemius. This is also noted to be approximately half the distance between the inferior aspect of the patella and the medial malleolus ( Fig. 9.2 ). In obese patients, palpation of the gastrocnemius can be quite difficult, and use of ultrasound to identify the fascia has been described. We have not found this to be necessary with the use of the anatomic landmarks described. The incision is made for approximately 4 cm, and may be lengthened if needed. The crural fascia overlying the gastrocnemius is encountered and must be incised. Closure of the crural fascia is not required, and we have not found closure to aid in the postoperative cosmetic appearance of the calf. The most critical aspect of the case is to protect the sural nerve which will lie directly posterior to the gastrocnemius at this level. The fat and nerve must be carefully dissected off of the posterior aspect of the gastrocnemius fascia, and although it can be difficult to visualize, it should be palpated posteriorly to ensure that transection of the fascia will not injure the nerve. We have found the nerve to occasionally lie directly adherent to the fascia, and the use of a freer to release the nerve from the fascia is very effective. A malleable retractor is then placed immediately posterior to the fascia anterior to the sural nerve. In many cases, the gastrocnemius can be isolated from the soleal fascia and transected with scissors. The foot is held in dorsiflexion to place tension on the fascia during release. Immediate correction of the deformity should be noted; if not, palpation will aid in identifying any remaining fascia that requires release. Postoperatively, we prefer to use a splint to minimize pain and maximize wound healing for 1 week. A controlled ankle motion (CAM) boot is then used for 3–4 weeks dependent on patient comfort. Physiotherapy is initiated at 4 weeks and advancement to regular shoes is allowed with resolution of the foot pain, to be expected within 3 months.
Dorsal Wedge Osteotomy
An incision is made over the neck of the metatarsal, and the dorsal aspect of the metatarsal head is visualized. The soft tissues, including the periosteum and extensor tendons, are retracted, and two pilot holes are inserted. These are unicortical holes, made with a 1-mm Kirschner wire (K-wire) and at a 45-degree angle to each other and placed approximately 1 cm apart. The osteotomy is performed in between these pilot holes. Not more than 1 mm of bone must be removed. Accordingly, the actual base of the osteotomy, including the thickness of the saw blade, is approximately 0.5 mm deep. A greenstick cut is performed, and the plantar cortex must be left intact. We prefer to complete the osteotomy with a fracture maneuver that actually opens up the initial cut using manual dorsal pressure on the head of the metatarsal. This maneuver preserves a nice periosteal bridge on the plantar surface, thereby preventing excessive dorsal shift of the metatarsal head. Fixation of the osteotomy is performed with a stout suture of 2-0 absorbable material on a tapered needle, which is easily passed through the predrilled holes. More extensive fixation is not necessary ( Fig. 9.3 ). Although we have performed this for more than one metatarsal at a time, multiple dorsal wedge osteotomies need to be carefully planned, because the risk for transfer metatarsalgia increases with the number of these osteotomies performed, and multiple Weil or Maceira osteotomies are preferable. For patients with Freiberg infraction, a dorsal closing wedge osteotomy is ideal. However, in these cases a large dorsal closing wedge is required to remove the nonviable and avascular bone. Fixation can be performed with suture as described previously or with the use of an obliquely placed 2.0- or 2.4-mm screw ( Fig. 9.4 ).
Lengthening of one metatarsal may need to be combined with shortening of another. This is a common problem with brachymetatarsia, in which one or more of the lesser metatarsals are short and metatarsalgia is present on the adjacent metatarsal ( Fig. 9.5 ). For these cases of brachymetatarsia, we prefer to use a single-stage lengthening of the involved metatarsals, combined with shortening of the adjacent metatarsals using a Maceira osteotomy. We correct brachymetatarsia according to the age of the patient and the number of metatarsals involved. Although gradual distraction of the metatarsal can be performed successfully, we prefer, wherever possible, to perform a single (nonstaged) lengthening using interpositional graft. This is certainly preferable when more than one metatarsal is involved, because the application of distraction to two adjacent lesser metatarsals is impractical. Nonetheless, gradual distraction is a reliable technique, provided it is tolerated by the patient.
