Comparison of Radiographic Outcomes Between TPLO + TTT and CTWO + TTT in Dogs with Concurrent Cranial Cruciate Ligament Rupture and Medial Patellar Luxation.

Cranial cruciate ligament (CrCL) rupture frequently occurs with medial patellar luxation (MPL) in small-breed dogs, and both conditions may be corrected during surgery using a proximal tibial osteotomy-tibial plateau leveling osteotomy (TPLO) or cranial tibial wedge osteotomy (CTWO)-combined with tibial tuberosity transposition (TTT). Because these osteotomies differ in patellar ligament displacement, they may interact differently with TTT. We retrospectively compared TPLO + TTT and CTWO + TTT in 20 stifles from 18 small-breed dogs. Tibial length was quantified using a normalized effective tibial length (NEL) referenced to the tibial mechanical axis, and patellar position was assessed using the Guénégo-Verwaerde index (GVI). Both outcomes were expressed as the within-limb relative changes to reduce the influence of positioning differences. NEL changed by -5.65 ± 1.29% after CTWO + TTT and -0.98 ± 0.93% after TPLO + TTT, with non-overlapping ranges in this sample. Postoperative GVI decreased in all 10 CTWO + TTT stifles (mean -14.6%) but was unchanged after TPLO + TTT (+1.7%, p = 0.73; between-group p = 0.002). Patellar descent corresponded to only about 26% of tibial shortening. Radiographic union was more advanced after TPLO + TTT at 8-10 weeks, although callus was present in every stifle and no non-union occurred. TPLO + TTT preserved tibial length and the patella-tibial plateau relationship.