Follow-up study of MRI for osteochondral lesion of the talus

Characteristic MRI findings of osteochondral lesions of the talus have been reported. We examined how they change before and after treatment and discu ssed their significance. Twenty two ankles in 21 patients had MRI examinati on before and after treatment of the talar lesion. We evaluated the changes in the low intensity areas in T1-weighted image and the signal rims behind osteochondral fragment in TS-weighted image which have been reported as ch aracteristic findings. Clinical symptoms were improved postoperatively in a ll subjects. The low intensity areas in T1-weighted image seen before the s urgical treatment tended to decrease in sire postoperatively, The low inten sity area in T1-weighted image was reduced in 15 of the 22 ankles (68.2%). Low signal rim in TS-weighted image was seen in three cases before the trea tment. All disappeared completely after arthroscopic drilling. Similarly, h igh signal rim in T2-weighted image seen in 13 cases before the treatment d isappeared in 10 postoperatively. These findings were considered indicative that surgical treatments reduced abnormal stress of the underlying bone el ement due to unstable osteochondral fragment, leading to reduction of the l ow intensity area. The disappearance of signal rims in TS-weighted images w as considered to indicate obliteration of the interface between the osteoch ondral fragment and the talar bed with bone union. We believe that MRI of t he osteochondral lesion of the talus will be useful for postoperative evalu ation allowing assessment of the need for further treatment. The decreasing size of low intensity areas in T1-weighted images and disappearance of sig nal rims behind the osteochondral fragment in TP-weighted images suggested healing of the osteochondral lesions.