Subchondral lucencies of the proximal tibia in 17 horses.

Objective: To describe subchondral lucencies (SCL) in the equine proximal tibia, several treatment options, and clinical outcomes.

Study Design: Retrospective study.

Animals: Seventeen horses with proximal tibial SCL.

Methods: Medical record and radiograph review. Follow-up was obtained via examination and radiography when possible and by telephone and race records when required. The median duration of follow-up was 20 months (range, 0-48).

Results: Proximal tibial SCL were associated with lameness in 14 of 17 horses. Subchondral lucencies were primary in 11 horses and secondary to an ipsilateral medial femoral condyle SCL in six horses. One foal with a primary SCL was euthanized because of osteomyelitis. Six horses ≤1 year old with primary SCL were managed with exercise restrictions only; SCL in three horses without lameness decreased in size, whereas three horses with lameness did not improve. One young horse treated with surgical debridement failed to improve and was euthanized. Lameness resolved in three horses with primary tibial SCL treated with screw fixation. Screw fixation of secondary SCL in five horses led to a reduction in SCL size and degree of lameness.

Conclusion: Primary tibial SCL healed with rest in 3 non-lame young horses with small SCL, but was not successful in lame horses with larger SC. Radiographic size and associated lameness improved or resolved with screw fixation in primary and secondary proximal tibial SCL.

Clinical Significance: Primary tibial SCL that did not cause lameness healed with conservative management, but persistent primary and secondary tibial SCL required screw fixation to reduce lameness.