Osteochondritis dissecans of the knee: correlation of magnetic resonance imaging and arthroscopy

Twenty-three patients with osteochondritis dissecans of the knee were examined with MR imaging and subsequently under went arthroscopy. The youngest patient was 15 years old, and the eldest 42 years with mean age of 20.2 years. MR imaging permitted direct visualization of the lesion as well as the overlying articular cartilage in all cases. Based on the MR imaging findings 4 lesions were classified as stable [14.7%], 5 loose in situ [21.7%], and 14 grossly loose [60.9%]. Arthroscopically 5 lesions were classified as stable [21.7%], 4 loose in situ [17.4%], and 14 grossly loose [60.9%]. Correlation of these findings revealed that the MR imaging was accurate in separating loose from stable lesions in 95.7% of the cases. MR imaging is the only non-invasive radiologic tool that can provide direct and conclusive evidence of loosening as well as displacement of the lesion. These informations have assisted in deciding whether surgery is likely to be needed, and how the lesion should be approached

Role of CT and MRI in diagnosing clinically obscure orthopedic cases

Seventeen patients with non-diagnostic clinical and radiographic findings were studied with CT scan. MR imaging was done in 12 cases. The preoperative diagnosis has been improved by using these imaging modalities. Accurate localization of the lesion has facilitated the surgical procedure in all cases. 7 lesions were osteoid osteoma, 6 Brodie's abscess, and 4 tuberculosis. CT scan results were found to be in agreement with the surgical and biopsy findings in 82% of the cases. MR imaging was found to be superior to CT scan in delineating the soft tissues and marrow space involvement. CT scan was superior to MR imaging in showing cortical involvement and calcifications within the lesion. These data lend strong support to use these imaging modalities when conventional methods fail to show up the lesion