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Plantar Keratosis

- See: Orthotics for the Foot:

- Plantar Keratosis:
    - this callus is a circumscribed keratotic area which may or may not be associated with a hammered great toe;
    - kerkatosis often resembles verruca plantaris, for which it is mistakenly treated until the keratosis breaks down and ulcerates or leaves a permanent scar;
    - although keratosis under the first metatarsal head is common, it is more common to have disabling symptoms under the middle three metatarsals;
    - callus under the first metatarsal:
          - it is formed by the bearing of wt on the pointed area of a malformed or displaced tibial sesamoid, or occassionally, a fibular sesamoid;
          - often associated w/ sesamoiditis and can be related to a sharp pointed sesamoid;
          - in mild cases of callus under the first metatarsal head, proper redistribution of wt bearing by means of a shoe inlay or Thomas bar relieves the lesion;
          - in severe cases, excision of the plantar surface of the offending sesamoid or both are necessary;
          - reference:
                 - Tibial sesamoid shaving for treatment of intractable plantar keratosis.
    - callus under the middle three metatarsals:
          - callus under the middle metatarsals is secondary to a depressions of anterior arch and is often accompanied by contracted or 
                 hammered toes (claw toes);
          - plantar surface of the head of each of the lesser metatarsals has two condylar projections, these may end in sharp points;
          - condylar projection on fibular side is always larger of two;
          - middle three metatarsals form the dome of the anterior metatarsal arch, which functions as a shock absorber and was meant to bear 
                 wt only briefly during each step;
          - because modern foot wear buckles the MP joints, almost everyone has a depressed anterior arch;
          - therefore, the palmar condyles of the metatarsals almost always bear full wt, and may gouge the soft tissues underneath;
          - skin underneath sharp condyles may be subject to fibrotic changes as protective measure;
                 - greater the accumulation of horny layers, the less space there is between the condylar surface and contact area;
                 - further compression of soft tissues covering these areas occurs;
    - callus under the 5th metatarsal head:
          - callus is generally result of faulty wt distribution of foot, which forces 5th metatarsal to bear excessive amount of total body wt;
          - sometimes the callus is caused by an unusually pointed plantar condyle of the metatarsal head;
          - metatarsal inlay or a Thomas bar added to a properly fitted shoe corrects most mild cases

- Treatment:
    - w/ plantar corns, palliative measures such as reduciton of the horny accumulation and then padding of the area to distribute pressure 
          give relief in most cases;
    - intractable conditions over a non wt bearing area respond to excision of the condylar prominence;
    - calluses are basically caused by shoes w/ pointed toes, short toes, or both, that force the toes to buckle and thus produce a hammar 
          toe deformity at the MP joints

Intractable plantar keratosis.