Assessment of radiographic healing after tibial plateau leveling osteotomy in young and older dogs using the modified RUST scoring system

ObjectiveTo compare radiographic osteotomy healing scores after tibial plateau leveling osteotomy (TPLO) in young (2–5 years) and old (8–12 years) dogs using the modified Radiographic Union Score for Tibial fractures (mRUST) system, and to evaluate agreement between large language model-assisted interpretation (LLM), surgeon, and surgical resident scoring.Study designClient-owned, 20–40 kg dogs treated with unilateral TPLO at ages 2–5 or 8–12 years between 2023 and 2025 were retrospectively identified. Dogs with endocrinopathy or atypical TPLO or recovery were excluded. Dogs were assigned to Group 1 (2–5 years) or Group 2 (8–12 years). 8-week postoperative radiographs were scored independently by an LLM, a surgeon, and a surgical resident using the 4-point mRUST system. Scores were compared between age groups using the Wilcoxon rank-sum test, and interrater agreement was assessed using an intraclass correlation coefficient (ICC).ResultsGroup 1 had 49 dogs; Group 2 had 51 dogs. Group 1 had a mean (SD) age of 3.82 (1.11) years, while Group 2 had a mean (SD) age of 9.24 (0.99) years. mRUST scores did not differ between age groups across LLM (p = 0.352), surgeon (p = 0.908), or resident assessments (p = 0.588). LLM, surgeon, and resident scores had only fair agreement (ICC = 0.4504, p < 0.001).ConclusionChronological age was not associated with mRUST score following TPLO at the 8-week postoperative evaluation. The mRUST system demonstrated moderate agreement between human observers. LLM scoring showed promise; further refinement is needed for clinical application.