Koehler Disease
Summary
Koehler Disease (often spelled Kohler's) is a rare, self-limiting avascular necrosis (osteochondrosis) of the tarsal navicular bone affecting young children (Boys 4-7 years old). It presents as a limping child with pain and swelling over the medial midfoot. The navicular, which is the last tarsal bone to ossify, undergoes a temporary interruption of blood supply, causing it to collapse and become sclerotic (dense). The classic radiographic appearance is a flattened, wafer-thin, white bone ("Silver Dollar Sign"). Crucially, unlike adult AVN (Muller-Weiss), Koehler's disease has an excellent prognosis. It spontaneously revascularizes and reconstitutes over 1-3 years, usually leaving no long-term deformity or pain. [1,2,3]
Key Facts
- The Last Bone: The Navicular is the last foot bone to ossify (Age 2-3 in girls, 4-5 in boys). This delayed ossification makes it vulnerable to compression between the already-ossified Talus and Cuneiforms.
- The Sclerosis: On X-ray, the bone looks "dead" (bright white and squashed). Parents panic. You must reassure them: "This looks bad, but it heals perfectly on its own."
- The Difference:
- Koehler's: Child (Start). Biological plasticity. Heals.
- Muller-Weiss: Adult (End). Biological failure. Crumbles.
Clinical Pearls
"Walk it off": Many kids with Koehler's continue to run and play despite the limp. The pain is rarely severe enough to stop activity completely.
"The Comma": Sometimes the collapsing navicular takes on a comma shape on the lateral view before it reforms.
"Don't Operate": There is absolutely no role for surgery in Koehler's disease. Biopsy or drilling will only damage the cartilage and potential growth plate.
Demographics
- Age: 3-7 years (Peak age 5). (Rare >9).
- Gender: Boys > Girls (5:1).
- Bilateral: 25% of cases (but often asynchronous onset).
Anatomy
- Blood Supply: The navicular is supplied by a centripetal network from the dorsalis pedis and medial plantar arteries.
- Vascular Watershed: The central body of the navicular is a watershed zone (poor perfusion), similar to the scaphoid waist.
Mechanism
- Compression: As the child grows and becomes more active (jumping), the cartilaginous navicular is compressed between the Talus and Cuneiforms. The vessels are squeezed, leading to ischemia and osteocyte death.
- Revascularization: Creeping substitution occurs. New vessels grow in, removing dead bone and laying down new bone.
Symptoms
Signs
Imaging
- X-Ray (Weight Bearing):
- AP/Lateral:
- Sclerosis: Increased density (Whiter than other bones).
- Flattening: Loss of height (Wafer-like).
- Fragmentation: Breaking into pieces.
- AP/Lateral:
- MRI:
- Rarely needed.
- Shows loss of signal on T1 (AVN) and marrow edema on T2.
- Bone Scan:
- Cold spot (early) -> Hot spot (healing).
CHILD LIMPING
↓
X-RAY: DENSE NAVICULAR
┌───────────┴───────────┐
MILD PAIN SEVERE PAIN
(Can walk) (Refuses to walk)
↓ ↓
ACTIVITY MODIFICATION SHORT LEG CAST
(Arch Support / Shoe) (4-6 Weeks)
↓ ↓
FOLLOW UP RE-XRAY
(X-ray 6m) (Document healing)
Protocol
- Observation:
- If symptoms are mild, no treatment is needed other than avoiding high-impact sports.
- Soft arch support cushion.
- Immobilization (The Standard):
- Short Leg Walking Cast: 4-6 weeks.
- Purpose: Relieves pain and inflammation. Does not speed up the revascularization (which takes years) but makes the child comfortable.
- Williams et al: Showed that casting reduces the duration of symptoms (3 months vs 15 months for untreated).
Contraindicated
- Surgery has NO role.
- Drilling, grafting, or excision are harmful.
Flattened Navicular
- The bone may reconstitute in a slightly flattened shape. Usually asymptomatic.
Osteophytes
- Rarely, dorsal dorsal osteophytes form.
TN Arthritis
- Extremely rare in childhood onset.
To Cast or Not?
- Williams et al (JBJS 1983): A classic study comparing casting vs arch supports vs nothing.
- Cast: Pain resolved in 3 months.
- Support: Pain resolved in 7 months.
- Nothing: Pain resolved in 15 months.
- Conclusion: Casting is the most effective treatment for symptoms.
Long Term Outcome
- Ippolito et al (JPO 1984): Followed patients for 33 years. Found normal foot function and no arthritis in adulthood, regardless of the severity of the initial X-ray.
The Condition
The "keystone" bone in your son's foot has temporarily lost its blood supply. It's like a grape turning into a raisin.
The Good News
In children, this "raisin" will turn back into a grape. The bone has an amazing ability to heal itself. It will grow back to normal shape.
The Plan
We will put him in a cast for 4 weeks to stop the pain. Then he can run and play as much as he likes. It will heal perfectly.
- Williams GA, Cowell HR. Kohler's disease of the tarsal navicular. Clin Orthop Relat Res. 1981.
- Ippolito E, et al. Long-term follow-up of Kohler's disease of the tarsal navicular. J Pediatr Orthop. 1984.
- Karp MG. Kohler's disease of the tarsal scaphoid: an end-result study. J Bone Joint Surg Am. 1937.
Q1: At what age does the tarsal navicular normally ossify? A: Girls: 2-3 years. Boys: 4-5 years. It is the last tarsal bone to ossify.
Q2: Differentiate Koehler's Disease from Muller-Weiss Syndrome. A:
- Koehler's: Childhood (4-7), Males, Spontaneous vascular etiology, Reconstitutes to normal, Excellent prognosis.
- Muller-Weiss: Adulthood (40-60), Females, Dysplastic/Traumatic etiology, Fragments and collapses, Poor prognosis (Arthritis).
Q3: Does the severity of radiographic fragmentation correlate with outcome? A: No. Even completely fragmented and flattened naviculars in children reconstitute to a normal or near-normal shape with normal function.
Q4: What is the primary differential diagnosis for a dense navicular in a child? A: Normal irregular ossification. The navicular can often ossify from multiple centers, appearing fragmented. Clinical correlation (pain/limp) is essential to diagnose Koehler's.
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