Computed tomography analysis of osteochondral defects of the talus after arthroscopic debridement and microfracture

Abstract

Purpose: The primary surgical treatment of osteochondral defects (OCD) of the talus is arthroscopic debridement and microfracture. Healing of the subchondral bone is important because it affects cartilage repair and thus plays a role in pathogenesis of osteoarthritis. The purpose of this study was to evaluate the dimensional changes and bony healing of talar OCDs after arthroscopic debridement and microfracture.

Methods: Fifty-eight patients with a talar OCD were treated with arthroscopic debridement and microfracture. Computed tomography (CT) scans were obtained at baseline, 2 weeks postoperatively, and 1 year postoperatively. Three-dimensional changes and bony healing were analysed on CT scans. Additionally, clinical outcome was measured with the American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score and numeric rating scales (NRS) for pain.

Results: Average OCD size increased significantly (p < 0.001) in all directions from 8.6 (SD 3.6) × 6.3 (SD 2.6) × 4.8 (SD 2.3) mm (anterior-posterior × medial-lateral × depth) preoperatively to 11.3 (SD 3.4) × 7.9 (SD 2.8) × 5.8 (SD 2.3) mm 2 weeks postoperatively. At 1-year follow-up, average defect size was 8.3 (SD 4.2) × 5.7 (SD 3.0) × 3.6 (SD 2.4) mm. Only average defect depth decreased significantly (p < 0.001) from preoperative to 1 year postoperative. Fourteen of the 58 OCDs were well healed. No significant differences in the AOFAS and NRS-pain were found between the well and poorly healed OCDs.

Conclusion: Arthroscopic debridement and microfracture of a talar OCD leads to an increased defect size on the direct postoperative CT scan but restores at 1-year follow-up. Only fourteen of the 58 OCDs were filled up completely, but no differences were found between the clinical outcomes and defect healing at 1-year follow-up.

Level of evidence: IV.

Keywords: Ankle; Arthroscopy; Cyst; Microfracture; Osteochondral defect; Subchondral bone.

Fig. 1

Mean defect size measured on the preoperative, two weeks postoperative, and one year postoperative CT scans. The error bars represent the standard deviation. Significant differences are indicated (asterisk)

Fig. 2

a Preoperative coronal (A1) and sagittal (A2) CT scans of a right ankle show a cystic OCD of the medial talar dome, b the two weeks postoperative coronal (B1) and sagittal (B2) CT scans show an increased defect size after technically successful debridement and microfracture, c at 1-year follow-up, the defect size decreased and the level of subchondral bone plate was almost flush [coronal CT scan (C1); sagittal CT scan (C2)]

Fig. 3

a Preoperative coronal (A1) and sagittal (A2) CT scans of a left ankle with a cystic OCD of the lateral talar dome, b the two weeks postoperative coronal (B1) and sagittal (B2) CT scans show that the cystic OCD is opened but not debrided, c at 1-year follow-up, the cyst is still visible [coronal CT scan (C1); sagittal CT scan (C2)]

Fig. 4

Follow-up of cyst formation after debridement and microfracture of OCDs of the talus. The two new cysts developed from a noncystic OCD were adequately treated during surgery

Fig. 5

a Preoperative coronal (A1) and sagittal (A2) CT scans of a left ankle with a cystic OCD of the medial talar dome, b the two weeks postoperative coronal (B1) and sagittal (B2) CT scans show that the cystic OCD is opened and a microfracture hole is visible, c at 1-year follow-up, a new cyst has developed, possibly out of a microfracture hole [coronal CT scan (C1); sagittal CT scan (C2)]