Kohler's Disease I

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- Discussion:
    - self limiting avasulcar necrosis of the navicular;
    - usually unilateral and affects children, most often boys;
    - onset is at age 4 in boys and age 5 in girls;
    - navicular is subjected to repetitive compressive forces during wt bearing which may be a risk factor for AVN;
            - navicular is last bone in foot to ossify & delayed ossification appears to make the navicular
                  more vulnerable to compressive damage;
            - compressive forces can occlude the vessels of the soft ossification center redering it avascular;
    - prognosis:
            - disease is self limiting & prognosis is excellent;
            - navicular typically regains its normal shape before foot completes growth, and normal ossification
                    is usually completed in two years;

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- Clinical Manifestations:
    - painful limp, shifting weight to lateral edge of foot to relieve pressure on longitudinal arch;
    - pain tenderness, and swelling develop in the region of the navicular;
    - contraction of tibialis posterior muscle may be painful;

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- Radiologic Findings:
    - navicular shows patchy areas of sclerosis and rarefication w/ loss of normal trabecular pattern;
    - navicular may appear collapsed or in some cases will have normal shape with a uniform increase
            in density and minimal fragmentation;
    - it is occassionally seen on opposite, asymptomatic foot;

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- Treatment:
    - symptomatic treatment is needed for the pain and swelling;
    - soft longitundinal arch supporters, medial heel wedge, and limitation of strenuous activity;
    - if pain is severe or persists, a short leg walking cast may be used for 4 to 6 weeks, followed
            by use of shoe modifications;

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  Koehler's disease of the tarsal navicular:   Long-term follow-up of 12 cases.
      Ippolito E, Ricciardi-Pollini PT, Falez F: J Pediatr Orthop 1984;4:416-417.

  Koehler's disease of the tarsal navicular.   Clin
      Williams GA, Cowell HR: Orthop 1981;158:53-58.

  The Ossification and Vascularisation of the Tarsal Navicular and Their Relation to Kohler's Disease.
      Waugh, W. J Bone Joint Surg, 1958; 40-B:765-777.