Epidemiology and Characteristics
- Most occur from an injury – may be minor
- Some may be secondary to localized AVN or metabolic problems
Location
- 70% medial and 30% lateral
- Usually are posteromedial and anterolateral
- Lateral are almost always traumatic
- Lateral tend to be unstable
- Medial more cystic and more stable
- 10% have a corresponding kissing lesion on the tibial plafond
Classification
Berndt & Hardy
- Stage 1 – Subchondral fracture
- Stage 2 – Partially detached fragment
- Stage 3 – Detached but stable fragment
- Stage 4 – Detached and unstable fragment – free floating
- This system is based on XR and 50% of OCDs are not seen on XR
- Newer MRI classifications (e.g., Bristol) use MRI
- Incorporate bone oedema into their classification
Clinical Features
- Usually a history of injury, even if minor and some time ago
- Pain is the main feature
- Does not settle with non-operative modalities
- Synovitis can cause secondary impingement
Investigation
- Visible in 50% on plain X-rays
MRI
- Gold standard for quantifying lesion, degree of oedema, and other pathology
Management
Non-Operative
- May help – injection, physio, and activity modification
- Natural history of OCD is not yet known
- No current correlation with symptomatic OA
- RCT in 2000 (Tol et al.)
- Showed improvement in 50% with non-operative and 80% with debridement
- Therefore, have a low threshold for arthroscopic debridement
Surgical Treatment
- Treatment of choice is arthroscopic debridement
- Chondral flaps and loose bodies
- Microfracture or curettage to bleeding bone for chondral defects
- Cartilage grafting (ACI, MACI, Plugs, Mosaicplasty, etc.)
- Not proven in the ankle
- Can be considered for larger areas of cartilage loss
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