The usual presenting complaints are
- Intermittent pain in the joint on strenuous physical activity
- Stiffness
- Swelling
- Clicking and locking of the joint
- Limp
When the knee joint is involved, “giving way” of the knee is a frequent complaint.
Physical Findings
These depend on the joint involved, the duration of the disease, and whether or not the fragment has become detached.
An important finding is localized tenderness over the lesoinal area.
In knee it iis usually over the lateral surface of the medial femoral condyle and is best elicited by deep pressure over the lesion with the knee acutely flexed.
When the medial femoral condyle is the site of the lesion, the patient will toe out; lateral rotation of the tibia prevents the tibial spine from impinging on the lateral surface of the medial femoral condyle.
Wilson’s sign
With the patient in supine position, the affected knee is flexed to a right angle, the leg is medially rotated fully, and then the knee is gradually extended. At 30 degrees of flexion, the patient will complain of pain over the anterior aspect of the medial femoral condyle. The pain is relieved on lateral rotation of the leg.
Atrophy of the controlling muscles, synovial thickening, hydrarthrosis, and limited joint motion are common. One may be able to palpate the loose body may be palpated.
When ankle is involved, there is intermittent pain on weight-bearing aggravated by strenuous physical activity such as running and sports. Limp is common.
At times, the condition is asymptomatic.
Physical findings include localized tenderness which can be detected by markedly plantar-flexing the ankle joint and palpating the medial and lateral corners of the dome of the talus.
Pressure can be exerted on the dome of the talus by rotating the leg inward and outward while the foot remains on the floor in plantar flexion and inversion, then in dorsiflexion and eversion.
Atrophy of the calf is common.
Radiography
The radiograph shows a well-circumscribed fragment of subchondral bone is demarcated from the surrounding femoral condyle or affected bone by a radiolucent saucer or crescent-shaped line. The affected bone may appear denser than the surrounding parent bone.
As the fragment separates, a depression is seen at the site of separation. However the detached loose body in the joint continues to grow deriving its nutrition from synovial fluid. Osteochondritic fragment becomes radiopaque is due to subchondral bone with articular cartilage, secondary calcification in degenerating articular cartilage and new bone formation following revascularization.
Special views may be necessary to visualize the lesion.
Computed Tomography
The CT scan makes possible a definitive diagnosis and determines the precise location and true extent of the lesion. It also reveals whether the fragment is detached completely or partially.
Bone Scanning with Technetium-99m shows localized increased activity at the site of the lesion.
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