Radiographic changes and clinical results of osteochondral defects of the talus with and without subchondral cysts

Background: Subchndral cysts are a type of osteochondral defect of the talus and can be a source of chronic ankle pain. The treatment modality of this cystic lesion is similar to that of other osteochondral defects, but results from previous reports are controversial. Therefore, we compared the clinical results and radiographic changes in small subchondral talar cystic lesions (less than 1.5 cm²) to other noncystic defects after arthroscopic operations without bone grafting. Methods: The review covered about 2 years (January, 2001 to April, 2003) and included 38 patients with an average age of 36.9 years. Followup ranged from 24 to 36 months. Arthroscopic microfracture or abrasion arthroplasty was performed on 20 defects with subchondral cysts and 18 defects without cysts. Clinical results were assessed by the ankle-hindfoot scale of the American Orthopaedic Foot and Ankle Society (AOFAS); radiographic changes were assessed by the transverse long diameter and the area (mm ²) of the cyst on digital radiographs using a PACS (Picture Archiving Communication System). Results: At the last followup, AOFAS clinical scores improved similarly in cystic and noncystic defects. The average diameter of the cysts decreased from 8 ± 2 mm to 6 ± 2 mm (p < 0.01). The area attributed to the cyst also decreased, from 49 ± 17 mm² (24 to 84 mm²) to 23 ± 8 mm² (4 to 34 mm²) (p < 0.01). There were no differences in the clinical results between the cystic and noncystic defects. Conclusions: Good clinical and radiographic results were obtained after arthroscopic treatment of osteochondral defects with a small subchondral cyst. Our results suggest that a small cystic lesion can be treated by arthroscopic microfracture or abrasion arthroplasty and that the existence of a small cyst in an osteochondral defect lesion may not affect the postoperative prognosis.