Synovial Chondromatosis

Classification of Loose Bodies

Loose bodies can be of 3 types depending on its etiology:
  • loose bodies due to Synovial Chondromatosis
  • loose bodies due to Osteochondral fracture
  • loose bodies due to joint surface disintegration

    • Three different types of cartilage can be identified in the nidus of a loose body–
      a) articular,
      b) osteophytic, &
      c) lobular.

      Three mechanisms for the generation of loose bodies in cases of degenerative arthritis or avascular necrosis are:
      1. fragmentation of the joint surface
      2. fractured osteophytes
      3. osteochondral nodule proliferation in the pararticular soft tissues

      4. For more details please read this article:
        The classification of loose bodies in human joints
        by Milgram JW.

        Synovial Chondromatosis

        -A proliferative disease of the synovium resulting from cartlaginous/osteocartilaginous metaplasia in the synovium of joints, bursae or tendon sheath.
        -multiple cartilaginous nodules develop & grow in the synovium of a joint
        -results in multiple intra-articular loose bodies.

        -30-50 years
        : = 2:1
        -knee, the most common site


        • SITE
          -Knee, elbow, ankle, hip & shoulder (in that order of frequency)
          -usually monoarticular but may affect both knee
        • Macroscopic features
          -hundreds of spheroid nodules protruding into the joint cavity
          -formation of rice-bodies/joint mice
          Snow storm appearance on arthroscopy
        • Microscopic features
          -hyaline cartilage formation at stratum synoviale at the synovial reflection
          -Chondroid masses appearance at the tips of synovial villi
          -surrounding cells altered to resemble chondroblast
          -Cartilage mass grows to form spheroid body with villous process as its pedicle.
          -spheroid body detaches & falls free into joint space
          -Chondroblast continue to proliferate & form spheroid cartilage
          -Chondroblast metaplsia into Osteoblast forming nidus of bone surrounded by cartilage
          -Joint-distended with uniform glistening white bodies
          -repeated trauma to articular surface causing multiple erosions & subsequently osteoarthritis

        Clinical features

        • Symptoms:
          -usually mild & slow progression of the symptoms
          -Pain, dull aching type
          -Transient locking episodes
        • Signs(Physical Examination):
          -generalized joint tenderness
          -warmth, erythema
          -decreased ROM (range of motion)
          -thickened synovial membrane
          -marked audible & palpable crepitus
          -loose bodies may be felt.

        Imaging evaluation

        1. Radiograph/Plain x-ray:
          -AP & Lateral views of the joint——— variable finding(s)
          -stippled calcification
          -multiple loose bodies (if calcified), number is always more than what can be seen in the X-ray.
        2. MRI:
          -best to see initial chondromatous(cartilage) nodules (Lobular appearance)
          -when calcified, signal drop-out consistent with calcification
        3. Double contrast/air Arthrography: can be used for all cartilaginous lesion(s).

        -individual hyaline cartilage nodules (various stages of calcification & ossification)
        -Chondrocyte showing mild atypia, binucleate cells & occasional mitoses
        Differential diagnosis
        -Rheumatoid arthritis: fragments of articular cartilage detach & augment into synovium or goes free in the joint.
        -Osteoarthritis: many osteophytes may detach into the joint.


        1. Conservative/Non-operative:
          -Obsevation if movement of the joint is not affected.
        2. Operative/Surgical:
          Synovectomy (open vs arthroscopic) plus loose bodies resection, indicated in cases with severe symptoms affecting the joint movement.
          -early intervention prevents the degenerative joint changes.
          Total synovectomy with excision of all communicating bursae
          -In case of knee joint, the damaged menisci may need removal
          -If the degenerative changes have already developed, the patient should warn about residual symptoms.

        -chances of Recurrence is there
        -Malignant transformation (very rare)