To diagnose<unk> , an X-ray, CT scan or MRI scan can be performed to show necrosis of subchondral bone, formation of loose fragments, or both. Occasionally a nuclear medicine bone scan is used to assess the degree of loosening within the joint. Physical examination Physical examination often begins with examination of the patient's gait. In<unk>  of the knee, people may walk with the involved leg externally rotated in an attempt to avoid tibial spine impingement on the lateral aspect of the medial condyle of the femur. Next, the examining physician may check for weakness of the quadriceps. This examination may reveal fluid in the joint, tenderness, and crepitus. The Wilson test is also useful in locating<unk>  lesions of the femoral condyle. The test is performed by slowly extending the knee from 90 degrees, maintaining internal rotation. Pain at 30 degrees of flexion and relief with tibial external rotation is indicative of<unk> . Physical examination of a patient with ankle<unk>  often returns symptoms of joint effusion, crepitus, and diffuse or localized tenderness. Examination often reveals symptoms of generalized joint pain, swelling, and times with limited range of motion. Some with loose body lesions may report catching, locking, or both. The possibility of microtrauma emphasizes a need for evaluation of biomechanical forces at the knee in a physical examination. As a result, the alignment and rotation of all major joints in the affected extremity is common, as are extrinsic and intrinsic abnormalities concerning the affected joint, including laxity. Diagnostic imaging X-rays show lucency of the ossification on the anterior aspect of the knee in juvenile patients. In older people, the lesion typically appears as an area of osteosclerotic bone with a radiolucent line between the osteochondral defect and the epiphysis. The visibility of the lesion depends on its location and on the amount of knee flexion used. Harding described the lateral X-ray as a method to identify the site of an<unk>  lesion. Magnetic resonance imaging (MRI) is useful for staging<unk>  lesions, evaluating the integrity of the joint surface, and distinguishing normal variants of bone formation from<unk>  by showing bone and cartilage edema in the area of the irregularity. MRI provides information regarding features of the articular cartilage and bone under the cartilage, including edema, fractures, fluid interfaces, articular surface integrity, and fragment displacement. A low T1 and high T2 signal at the fragment interface is seen in active lesions. This indicates an unstable lesion or recent microfractures. While MRI and arthroscopy have a close correlation, X-ray films tend to be less inductive of similar MRI results. Computed tomography (CT) scans and Technetium-99m bone scans are also sometimes used to monitor the progress of treatment. Unlike plain radiographs (X-rays), CT scans and MRI scans can show the exact location and extent of the lesion. Technetium bone scans can detect regional blood flow and the amount of osseous uptake. Both of these seem to be closely correlated to the potential for healing in the fragment. File:CT and projectional radiography of<unk>  - annotated.CT scan and projectional radiography of a case of<unk>  of parts of the superio-medial talus. File:OCD WalterReed MRI-Sagital-T1.Sagittal MRI: Linear low T1 signal at the articular surfaces of the lateral aspects of the medial condyle of the femur confirms the presence of<unk> . File:OCD WalterReed MRI-Sagital-T2.Sagittal MRI: High T2 signal at the articular surfaces of the lateral aspect of the medial femoral condyle confirms the presence of<unk> . Diffuse increase in T2 signal at the medial femoral condyle indicates marrow edema. Classification<unk>  is classified by the progression of the disease in stages. There are two main staging classifications used; one is determined by MRI diagnostic imaging while the other is determined arthroscopically. However, both stagings represent the pathological conditions associated with<unk> 's natural progression. While the arthroscopic classification of bone and cartilage lesions is considered standard, the Anderson MRI staging is the main form of staging used in this article. Stages I and II are stable lesions. Stages III and IV describe unstable lesions in which a lesion of the cartilage has allowed synovial fluid between the fragment and bone. + MRI staging of<unk>  Stage Evaluation Findings I Stable Articular cartilage thickening II Stable The articular cartilage is breached; low signal behind the fragment indicates fibrous attachment III Unstable The articular cartilage is breached; high signal behind the fragment indicates loss of attachment IV Unstable Formation of loose bodies + Cheng arthroscopic staging of<unk>  Grade Findings A Articular cartilage is smooth and intact but may be soft or ballottable B Articular cartilage has a rough surface C Articular cartilage has fibrillations or fissures D Articular cartilage with a flap or exposed bone E Loose, nondisplaced osteochondral fragment F Displaced osteochondral fragment
Osteochondritis dissecans
Tennis elbow
Osteochondrosis
Osteochondroma
Myositis ossificans
Osteitis pubis
Osteitis fibrosa cystica
Synovial osteochondromatosis