Long-term effects of tibial plateau leveling osteotomy and tibial tuberosity advancement on tibial plateau subchondral bone density in dogs.

OBJECTIVE: To evaluate long-term loading patterns using subchondral bone density (SBD) distribution of the tibial plateau after tibial plateau leveling osteotomy (TPLO) and tibial tuberosity advancement (TTA).

STUDY DESIGN: Cross-sectional study.

ANIMALS: Adult (> 2 years), medium to large breed dogs (>20 kg) that had been treated with TPLO or TTA at least 1 year prior to the study were recruited. A normal cohort of similar age and weight dogs with normal physical and orthopedic examinations served as control.

METHODS: Dogs were sedated for computed tomography (CT) of the stifle, and DICOM (digital imaging and communications in medicine) files were processed for CT osteoabsorptiometry (CTOAM). Tibial plateaus were sampled at 6 zones, and CTOAM was used to determine regional and maximal areas of SBD as a marker of joint loading.

RESULTS: Data were collected on 48 stifles in 31 dogs (15 TPLO, 11 TTA, 22 control). Lower Hounsfield unit (HU) values were measured in the caudal and mid-region of the lateral tibial plateau after TPLO and compared to normal. HU values did not differ between joints treated with TTA and those in the control group.

CONCLUSION: TPLO may alter stifle load distribution relative to the normal control group. There were no differences between TTA and the control group.

CLINICAL SIGNIFICANCE/IMPACT: Despite ongoing osteoarthritis (OA) in dogs after surgical intervention for cranial cruciate disease, changes in tibial SBD are minor and may not correlate with clinical function.