Metatarsalgia

Discussion:

  • In the normal foot, metatarsal heads bear one half of a person's body weight when the foot is plantigrade.
  • The first metatarsal normally bears half the weight of the forefoot.
  • A long second metatarsal can contribute to pressure under the metatarsal head.
  • Limitation of dorsiflexion (from heel cord contracture or ankle impingement) can contribute to diffuse metatarsalgia.
  • Claw toes will concentrate weightbearing on metatarsal heads.
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Bunion:

  • As the proximal phalanx moves into valgus and the splay between the first and second metatarsals increases, the first metatarsal base at the first cuneiform-first metatarsal joint also moves into varus and elevates, creating in many instances, less weightbearing than normal on the first metatarsal head relative to the second.  This sets up a potential transfer lesion to the adjacent head.
  • Hypermobility of the first MTC joint may also contribute to transfer metatarsalgia.

Sesamoids:

  • The tibial sesamoid normally assumes most of the weightbearing fracture transmitted to the head of the first metatarsal.
  • Because the sesamoids are embedded in the tendon of the FHB, which inserts into the base of the proximal phalanx, any degree of hallux valgus tends to rotate both sesamoids on the long axis.
  • The fibular sesamoid tends to rotate into the first metatarsal interspace, thereby disposing of the possibility of it becoming a weightbearing focus.
     


Differential diagnosis:

  • Injury/degenerative changes with resultant arthritis (hallucis rigidus).
  • Neuroma.
  • Pain in the metatarsal head may be caused by perineural fibrosis of intermetatarsal plantar digital nerves (Morton's neuroma).

Sesamoids:

  • With hallux valgus, sesamoids may be displaced laterally.
  • Fractures of sesamoids are infrequent and must be distinguished from bipartite sesamoids.
  • Loss of metatarsal fat pad.
  • Metatarsal stress fracture/reaction.
  • Localized verruca plantaris.
  • Abnormally long second metatarsal.
  • Unless the foot is free to deviate laterally, the second metatarsal takes an undue share of the body weight at push-off.
  • Absolute weakness of intrinsic muscles may also concentrate body weight on the second metatarsal due to decreased ability to depress adequately.
  • More mobile metatarsals.
  • Note how the second metatarsal is wedged between the three cuneiform bones, making it relatively immobile in relation to the midfoot.
  • Insufficient supination of the forefoot at push-off because of functional abnormality of the midfoot and hindfoot.
     

Non Operative Treatment:

  • Heel cord stretching if heel cord contracture is present.
  • Orthotics:.
  • Reduce forefoot pressure.
  • Transfer weightbearing to longitudinal and metatarsal arches.
  • Lower heel to reduce metatarsal head pressure (avoid high heel shoes).
  • Rocker bottom to shoe to reduce forefoot motion and pressures.
  • Severe angle rocker sole.
  • Has a more severe angle at the toe than standard designs.Has no heel rocker angle, which reduces weight-bearing pressures
    distal to the ball of the foot.
  • Indicated for extreme relief of metatarsal head or toe tip ulcerations.
  • Carefully placed metatarsal pad proximal to painful metatarsal head.
  • If metatarsalgia is due to a ruptured volar plate (such as in rheumatoid arthritis), often a stiff full length insole that limits MTP hyperextension of the foot is useful.
     

Operative Treatment:

  • Heel cord lengthening for ankle equinus deformity.
  • In the case of RA with intractable metatarsalgia, consider a Hoffman procedure.
  • With a transfer lesion due to a bunion deformity, the obvious treatment should be appropriate correction of the bunion (rather than the lesser metatarsalgia lesion).  This will recreate the windlass mechanism.
  • Long-oblique metatarsal osteotomy.
  • Chevron osteotomy.
  • Plantar fascia release may be appropriate for intractable metatarsalgia when it occurs with pes cavus.
  • Adjacent hammertoe may be addressed with severe central metatarsalgia.

The below patient had metarsalgia and a long second metatarsal that caused pain. In the following pics, a Weil osteotomy is performed to correct the 2nd toe joint

The second metatarsal is prepared for the osteotomy below

The Osteotomy has been made and the metatarsal head is shifted 3-4 mmm back and temporarily pinned. The overlap on the top can be seen prior to removal and recontouring the head.

The osteotomy is then permanently fixed with 2 screws

Below, Pics of fixation of Weil Osteotomy

Weil osteotomy has been made and the 2 pins are temporarily fixating the second metatarsal head. The metatardsal head is shifted back 3-4 mm as can be seen by the lip of bone at the top.

The blue and gold screw are permanently fixing the bone and the 2 wires are then removed.

Final view of the Weil osteotomy. Due to the displacement and drift of the toe, the metatarsal head was shortened and shifted 2 mm to the side as can be seen by the ridge of bone to the left.