Osteochondritis Dissecans

Not the Same as Osteochondral Defects (OCD)

  • Osteochondritis dissecans (OCD) may cause an osteochondral defect but is not the same.

Aetiology (Causes)

The causes are unknown, but three suggested theories are: 1. Hereditary: - Associations: Perthes disease, dwarfism, Stickler’s disease, tibia vara. 2. Vascular: - Paucity of blood supply just adjacent to the posterior cruciate ligament (PCL) on the medial femoral condyle (MFC). 3. Traumatic: - Repetitive microtrauma from shear forces.

Clinical Presentation

  • Mechanical symptoms:
    • Pain
    • Activity-related swelling
    • Catching
    • Locking

Imaging

  1. X-ray:
    • Standing AP/Lateral and Skyline views.
    • Notch view (knee flexed 30 degrees) shows posterior condyles better.
    • Malalignment may be contributory, especially in adults.
  2. MRI:
    • Gold standard for assessment.
    • Identifies or eliminates concurrent pathology.
    • Can assess stability, fragmentation, and lesion size.

Classification

  1. By Age of Onset:
    • Juvenile: Open physis.
    • Adult: Closed physis.
  2. By Location:
    • Typically on the lateral aspect of the medial femoral condyle (MFC).
    • May occur anywhere, but lateral condyle lesions are least common.
    • Lateral condyle lesions, if present, are associated with discoid meniscus or meniscectomy.
  3. Cahill Classification:
    • Classifies lesions by lateral position in relation to Blumensaat’s line.
  4. By Stability:
    • Type 1: Subchondral bone compression.
    • Type 2: Partially detached lesion.
    • Type 3: Fully detached lesion but still within the underlying crater.
    • Type 4: Loose body.

Prognostic Factors

Lesions with poorer outcomes include: - Closed physis (older children). - Atypical location. - Large size (>2 cm). - Unstable fragment. - Subchondral sclerosis on X-ray (poor response to drilling).

Management

  1. Non-Surgical:
    • Goal: Allow healing and prevent displacement of fragment.
    • Includes:
      • Activity modification
      • Analgesia (avoid NSAIDs)
      • ROM (Range of Motion) program
      • Restricted weight-bearing
  2. Surgical:
    • Goals: Stabilize fragments, restore articular congruity.
    • Treatment may be arthroscopic or open, with the same principles.
    If Fragments Are Preservable:
    • Antegrade transchondral microfracture: If the chondral surface is intact, it promotes healing underneath.
    • Fixation of fragments + microfracture/compression grafting: Used if the lesion is reparable; bioabsorbable pins are commonly used.
      • This is the treatment of choice for most cases.
    If Fragments Are Not Preservable:
    • Autologous Chondrocyte Implantation (ACI).
    • Autologous chondral plug transplantation.
    • Allograft transplantation.
    • Mosaicplasty.
    • Microfracture.
    If Malalignment in Adults:
    • Osteotomy +/- any of the above treatments.
    • Hemiepiphysiodesis to correct alignment if the physis is still open and limb malaligned.
Back to top