Hemicircular Tibial Plateau Leveling Osteotomy (hTPLO) for Dogs with Excessive Tibial Plateau Angles: A Comparative Study Using 3D Bone Models

A comparative study on hemicircular tibial plateau leveling osteotomy (hTPLO) and TPLO for correcting cranial cruciate ligament (CCL) ruptures at excessive tibial plateau angles (eTPAs) was performed with a specially fabricated hTPLO saw blade (hemicircular) and TPLO saw blade (quartercircular), respectively. Ten 3D-printed bone models with eTPAs (TPA > 40°), were resized to accommodate the respective saw blade shape for each method. Cranial closing wedge osteotomy (CCWO) combined with TPLO was also performed. Distances of segment rotation below the patellar tendon insertion (PTI) and differences between anatomical and mechanical axes after correction were measured. The TPAs of the bone models were 46.06 ± 4.40° (40.0–50.7°). Postoperative TPAs of hTPLO, TPLO, and TPLO combined with CCWO were 4.93 ± 1.025°, 4.52 ± 0.085°, and 4.17 ± 1.128°, respectively. Rotation distances from the PTI were 0.46 ± 2.153 mm, 8.67 ± 2.318 mm, and 1.13 ± 1.796 mm, respectively. hTPLO showed significantly less movement of the segment below the PTI than TPLO with or without CCWO (p < 0.01). Differences between anatomical and mechanical axes after hTPLO and TPLO with or without CCWO were 5.74 ± 2.231°, 6.43 ± 2.105°, and 5.16 ± 2.465°, respectively. Within the limitations of this model-based study, hTPLO demonstrated geometric feasibility for correction of excessive tibial plateau angles and was associated with less rotational displacement of the proximal tibial segment relative to the patellar tendon insertion than conventional TPLO and TPLO combined with CCWO. Further cadaveric, biomechanical, and clinical studies are required to evaluate its safety and clinical applicability.