Arthroscopic Treatment of Osteochondral Lesions of the Talus
Introduction
Definition—An osteochondral lesion of the talus (OLT) is a defect in the articular hyaline cartilage predominantly within the weight-bearing area of the talar dome that has underlying bone involvement
Etiology—Unclear; history of ankle trauma is implicated in most cases, but some occur without any traumatic events
Distribution of OLTs
Medial, deeper, and likely from impact on tibia: 62%
Lateral, thinner, and smaller from shear on fibula: 34%
In the central area: 80%
Symptoms—Ankle pain, instability, swelling, and catching
Imaging
Figure 1Coronal (A) and sagittal (B) CT scans demonstrate a stage III medial osteochondral lesion of the talus.
Radiographs of the ankle may show some chronic OLT lesions with bony changes and may miss small nondisplaced lesions
AP
Lateral
Mortise weight-bearing
MRI
Sensitive and specific for OLT lesions
Localizes lesion and depth
Excessive edema can obscure the bony extent of the lesion
CT is obtained when bone involvement cannot be delineated on MRI (Figure 1)
Classification
Figure 2Illustrations show the senior author’s (S.M.R.’s) grading system for osteochondral lesions of the talus (shown as medial lesions). See text for descriptions.
The senior author (S.M.R.) has proposed a grading system that combines various modality-specific classification systems (Figure 2)
Stage I OLT lesions involve an isolated cartilage flap without subchondral bone involvement
MRI demonstrates bone edema but no fracture
Radiographs and CT are usually negative
Ankle symptoms are mechanical and include painful catching and giving way
Stage II—Incomplete or completely nondisplaced fracture of underlying bone
MRI and CT show clear signs of fracture
Not visible on radiographs
Stable, may be best managed nonsurgically
Stage III—Unstable and displaced fragment of bone and cartilage
Radiographs, MRI, and CT all show lesion
Stage IV—Defect with no fragment remaining; frequently has fibrocartilage in the fragment
Stage V—Subchondral cysts with intact cartilage cap
Treat with retrograde drilling and bone grafting
Need to confirm healthy cartilage cap
Stage VI—Large area of chondral damage or cyst with communication to the joint; likely to need some form of osteochondral allograft
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