Radiographic and clinical changes of the tibial tuberosity after tibial plateau leveling osteotomy.

Objective: To investigate radiographic changes of the tibial tuberosity after tibial plateau leveling osteotomy (TPLO) surgery and identify clinical findings and risk factors associated with such changes.

Study Design: Retrospective study.

Sample Population: Hundred and eighty-six client-owned dogs (219 stifles) that had TPLO surgery.

Methods: Patient data retrieved included radiographic changes of the tibial tuberosity during re-examination, age, body weight, whether unilateral or single-session bilateral surgery had been performed, location of the anti-rotational pin, approximate tibial tuberosity area, and approximate average tibial tuberosity width.

Results: Fracture with resulting caudal displacement of the proximal tibial tuberosity (1.4%; 3 of 219) occurred less frequently than non-displaced tibial tuberosity fractures (7.3%; 16 of 219). Age, weight, average tibial tuberosity width, location of the anti-rotational pin, and single session bilateral surgery were identified as risks factors for non-displaced fracture. Weight divided by the square of the average tibial tuberosity width may be a stronger risk factor than either weight or average tibial tuberosity width alone.

Conclusions: Dogs undergoing single session bilateral TPLO surgery are at greater risk for developing non-displaced tibial tuberosity fractures. The non-displaced tibial tuberosity fracture does not appear to adversely affect outcome or lead to tibial tuberosity avulsion. Significant risk factors for fracture of the proximal tibial tuberosity with caudal displacement were not identified.

Clinical Relevance: Factors including age, weight, tibial tuberosity thickness, and conditions that may enhance strain on the tibial tuberosity, such as single-session bilateral procedures, may increase risk of fracture.