Approach Considerations
No laboratory studies are indicated in the workup of osetochondritis dissecans (OCD). Imaging studies, typically beginning with plain radiographs and often progressing to magnetic resonance imaging (MRI) scans, are used to confirm the diagnosis and guide treatment. Computed tomography (CT) scanning may be helpful in preoperative planning and in guiding treatment when MRI is not available or is contraindicated.Some authors advocate the use of arthroscopy as a diagnostic tool in addition to MRI prior to invasive procedures.
Imaging Studies
Imaging techniques used in the evaluation of osteochondritis dissecans (OCD) include the following:
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Plain radiography
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Scintigraphy
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Magnetic resonance imaging (MRI)
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Ultrasound
Radiography
Radiographic evaluation is an appropriate first-line investigation for OCD. [9] When detectable, an osteochondral lesion appears as lucency in the articular epiphysis. However, patients with very early lesions may have normal radiographic findings. In OCD in the knee, a notch or tunnel posteroanterior radiograph is the best way to visualize a lesion in the medial femoral condyle. Lateral and anteroposterior radiographs are also helpful in identifying OCD on the condyles.
See the images below.
Osteochondritis dissecans. Anteroposterior radiograph showing lucency in the medial femoral condyle.
Osteochondritis dissecans. Tunnel-view radiograph showing an osteochondral lesion of the medial femoral condyle.
Scintigraphy
Technetium bone scintigraphy is an important tool for evaluating OCD. The degree of osseous uptake is an important indicator of potential healing of the osteochondral fragment. The greater the uptake, the higher the apparent osteoblastic activity and the greater the likelihood for healing with conservative, as opposed to surgical, management. Some authors advocate the use of serial technetium imaging to stratify patient prognosis and guide treatment. Technetium imaging may also reveal occult bilateral involvement.
Magnetic resonance imaging
MRI is useful in the evaluation of patients with OCD (see the images below). It permits visualization of loose bodies and the degree of displacement. Lesions that appear normal on standard radiographs may be detected using MRI. MRI also permits determination of the fluid interfaces and the integrity of the articular surfaces. MRI is useful in preoperative planning to determine whether the fragment is detached and if so, to what degree. Intra-articular injection of gadolinium may be considered because it increases the sensitivity and specificity of MRI findings. [10, 11, 9, 12]
Osteochondritis dissecans. Sagittal view of an osteochondral lesion in the medial femoral condyle.
Osteochondritis dissecans. MRI sagittal view of an osteochondral defect in the medial femoral condyle.
Osteochondritis dissecans. MRI coronal view of an osteochondral defect in the medial femoral condyle.
Kijowski et al retrospectively compared the sensitivity and specificity of previously described MRI criteria for the detection of instability in patients with juvenile or adult OCD of the knee, with arthroscopic findings as the reference standard. Separately, previously described MR imaging criteria for detection of OCD instability were 0-88% sensitive and 21-100% specific for juvenile OCD lesions and 27-54% sensitive and 100% specific for adult OCD lesions. When used together, the criteria were 100% sensitive and 11% specific for instability in juvenile OCD lesions and 100% sensitive and 100% specific for instability in adult OCD lesions. The authors concluded from their findings that previously described MR imaging criteria for OCD instability have high specificity for adult but not juvenile lesions of the knee. [13]
Ultrasound
Sonography has been used to evaluate OCD of the knee and humeral capitellum. The advantages of sonography are lower cost than MRI and CT scanning, and dynamic scanning with motion of the affected joint. When performed by an experienced practitioner, ultrasonography may be an appropriate examination for evaluation of the humeral capitellum.
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Osteochondritis dissecans. Sagittal view of an osteochondral lesion in the medial femoral condyle.
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Osteochondritis dissecans. MRI sagittal view of an osteochondral defect in the medial femoral condyle.
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Osteochondritis dissecans. MRI coronal view of an osteochondral defect in the medial femoral condyle.
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Osteochondritis dissecans. Anteroposterior radiograph showing lucency in the medial femoral condyle.
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Osteochondritis dissecans. Tunnel-view radiograph showing an osteochondral lesion of the medial femoral condyle.
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Osteochondritis dissecans. Postoperative MRI coronal view showing pinning of the osteochondral defect.
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Osteochondritis dissecans. Postoperative MRI coronal view showing pinning of the osteochondral defect.
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Osteochondritis dissecans. Postoperative MRI sagittal view showing pinning of the osteochondral defect.
