MRI has Prognostic Value for OCD
MRI has Prognostic Value for OCD
Abstract & Commentary
Synopsis: The use of MRI was effective for decision making in patients with OCD both with and without surgery.
Source: Jurgensen I, et al. Arthroscopy. 2002;18(4):378-386.
The etiology of osteochondritis dissecans (OCD) remains unclear but perhaps is related to some type of stress mechanism in a watershed zone of vascularity. It commonly presents in adolescence and surgical intervention is reserved for symptomatic lesions. The key differential in assessing a patient with OCD is whether the fragment is loose or unstable. Jurgensen and colleagues used MRI to determine fragment stability and evaluated whether this could be an effective tool to direct treatment for OCD.
Over a 5-year period of time, 73 patients were recruited with the diagnosis of OCD at their hospital in Germany, which has a high number of patients with this diagnosis. Physical exam and MRI dictated initial treatment, which took into account the patient’s age and remaining growth potential. Those with symptomatic loose fragments presenting with locking and swelling underwent drilling with pin fixation arthroscopically (46 patients). The remaining 27 patients were treated conservatively with activity restriction and a short course of physical therapy. Nine of these 27 patients subsequently required surgery due to persistent or progressive symptoms.
Patients were evaluated with an MRI that involved a 1.5 T magnet with standard sequences that are well outlined in the paper, and were classified with a system devised by Kramer that focuses on the stability of the fragment and signal intensity at the interface between the fragment and the host bone. The patients underwent repeat MRI and physical exam at 2 years minimum. They found that patients who had a stable lesion maintained a stable lesion over time. On the contrary, if they had an unstable lesion, it was unlikely to become a stable lesion spontaneously. There was a small percentage of complete remission or reversal of the radiographic changes with conservative treatment (3.7%), but about one fourth of the patients improved symptomatically without surgical intervention. Interestingly, with surgery almost two thirds either had constant or increased symptoms and only 20% had complete resolution of their radiographic findings.
Because the MRI was effective in determining the stability of the lesion when correlated with the arthroscopic findings, Jurgensen et al recommended its use in evaluating and following both conservatively and surgically treated OCD lesions.
Comment by David R. Diduch, MS, MD
OCD remains a difficult problem to treat both surgically and conservatively. It is unclear whether activity modification has any therapeutic effect whatsoever. These can also be difficult to get to heal even with effective surgical intervention. The difficult thing has been determining who needs surgery. This hinges on whether the fragments are loose or unstable which cannot be determined by plain x-ray alone. Historically, bone scan has been used to assess this but involves a much longer study with radiation. MRI at this point has really supplanted bone scan in evaluation of the OCD lesion. The present study effectively shows that with routine sequences you can effectively determine stability of the lesion based on focusing at the interface between the OCD fragment and the host bone. High signal in this area suggests joint fluid or motion, which implies instability. These patients would generally be treated surgically as unstable lesions do not spontaneously stabilize in this or other series.
Patient age or remaining growth remains the single most important prognosticator for whether these will heal. So patients with significant growth remaining should generally be treated nonoperatively unless they have an unstable fragment. Jurgensen et al have demonstrated quite effectively that MRI can be used in that scenario to determine which fragments are loose and need intervention.
Dr. Diduch, Associate Professor, Department of Orthopaedic Surgery, University of Virginia School of Medicine, Charlottesville, is Editor of Sports Medicine Reports.
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