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case_images: (a, b, c, d) Radiographs of both crura at the time of presentation. There is a profound deformity of the proximal tibia resulting in an excessive tibial plateau angle, which was measured to be approximately 70 . There is cranial displacement of the proximal tibia, consistent with cranial cruciate ligament insufficiency.
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case_images: fig1
case_images: Orthogonal view radiographs of both crura and distal femora were obtained which revealed bilateral proximal tibial deformity characterized by excessive proximal procurvatum, resulting in an eTPA of approximately 70 , caudoproximal displacement of the tibial tuberosity, cranial subluxation of the tibia, slight patella alta, and mild secondary degenerative changes (Figures 1(a)-1(b)).
case_images: (a, b) Schematic representation of preoperative surgical planning for CCWO of the right tibia based on the preoperative mediolateral radiograph.
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case_images: fig2
case_images: The initial plan was to perform surgery on the right tibia first and reduce the eTPA using a CCWO (Figures 2(a) and 2(b)).
case_images: (a, b) Initial postoperative radiographs of the right crus after a cranial closing wedge ostectomy was performed. Note that the femoral condyles are positioned centrally over the tibial plateau, but the postoperative TPA was 20  with some minor valgus of the proximal tibia and external torsion. (c, d) Postoperative radiographs obtained following a revision procedure in which a tibial plateau leveling osteotomy was performed. The final TPA was 4  with improvement in the valgus and torsional deformity induced by the initial surgery.
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case_images: Postoperative radiographs revealed appropriately positioned osteotomies and implants, with the femoral condyles positioned centrally over the tibial plateau (Figures 3(a) and 3(b)). Postoperative radiographs revealed appropriately positioned implants and a TPA of 4  (Figures 3(c) and 3(d)).
case_images: (a, b) Orthogonal images of the virtually corrected tibia with the hybrid TPLO/reduction guide (magenta) positioned on the medial surface of the tibia and the adjoining cranial reduction guide (green) positioned on the cranial tibia.
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case_images: This guide consisted of material that conformed to the topography of the cranial surface of the virtually corrected tibia with five drill guide towers designed to accommodate 1.6 mm Kirschner wires inserted from cranial-to-caudal at converging and diverging angles (Figures 4(a) and 4(b)). TPLO jig pin placement, with an additional converging distal pin to compress the guide onto the tibial cortex. The proximal portion of the guide was designed with a 3 mm offset to accommodate the medial buttress. The amount of offset was an estimation:if an additional buttress was noted during surgery, it would have been dissected so that the guide position was not altered by soft tissues. The proximal aspect of this guide also incorporated a cylindrical osteotomy guide designed to accommodate a 27 mm TPLO saw blade (Colibri II, DePuy Synthes, Warsaw, Indiana, USA) (Figures 4(a) and 4(b)).
case_images: (a, b) Orthogonal images of the uncorrected virtual tibia with the cranial closing wedge/segmental tibial excision osteotomy guide (blue) positioned over the medial surface of the proximal tibia.
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case_images: fig5
case_images: A medially positioned osteotomy guide was designed using the centrally located virtually corrected tibial segments to dictate the locations of the proximal and distal tibial osteotomies (Figures 5(a) and 5(b)).
case_images: Intraoperative use of the 3D-printed osteotomy guide. (a) The cranial closing wedge ostectomy guide was secured to the medial surface of the tibia using 3.2 mm threaded pins. (b) The cutting shelves were used to precisely incise the tibia with a sagittal saw. (c) After completing the osteotomies, the free central tibial segment was removed. The guide was removed, but the pins securing the guide were left in place. The TPLO/reduction guide subsequently was placed over these pins to align and reduce the tibia.
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case_images: fig6
case_images: Texas, USA) (Figure 6). The appropriate guide location was subjectively easily identified. A sagittal saw (Colibri II, DePuy Synthes, Warsaw, Indiana, USA) was used to initiate the CCWO osteotomies using the custom guide cutting shelves (Figures 6(b) and 6(c)).
case_images: Intraoperative use of the TPLO/reduction and adjoining cranial reduction guides. (a) The TPLO/reduction guide was secured over the previously implanted parallel pins, which initially secured the cranial closing wedge osteotomy guide, to reduce and align the proximal and distal tibial segments. The cranial reduction guide was placed, and the proximal portion of the TPLO/reduction guide was used to direct the TPLO saw. (b) After the rotation of the plateau segment, an interfragmentary Kirschner wire was placed through the most proximal guide tower of the cranial reduction guide to maintain the rotation. The medially positioned TPLO/reduction guide was removed. The cranial reduction guide maintained the alignment of the tibial as the CBLO plate was applied. (c) After removing the cranial reduction guide, a precontoured conical coupling plate was secured to the cranial tibia to provide supplemental fixation.
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case_images: fig7
case_images: TPLO/reduction guide, a 27 mm TPLO saw blade was used to create a radial osteotomy in the proximal tibia, and the plateau segment was rotated 8.8 mm (Figure 7). The rotation was maintained by placing a final proximal interfragmentary Kirschner wire through the cranial reduction guide. Augustine, Florida, USA) plate applied to the medial surface of the proximal tibia (Figure 7(b)). The precontoured six-hole 3.5 mm conical coupling locking plate (Fixin, Intrauma S.p.A., Rivoli, Italy) was applied to the cranial tibia (Figure 7(c)).
case_images: (a, b) Initial postoperative radiographs of the left crus. The postoperative tibial plateau angle was estimated to be 8  based on these radiographs (later confirmed to be 7  on a subsequent CT), and the femoral condyles are positioned centrally on the tibial plateau.
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case_images: fig8
case_images: The TPA was estimated to be 8  but could not be definitely measured as the plateau was partially obscured by the CBLO plate (Figures 8(a) and 8(b)).
case_images: (a, b) Long-term follow-up radiographs of the left crus were obtained 46 months after surgery. There has been no loss of tibial alignment. The tibial and fibular osteotomies have healed and remodeled. The femoral condyles are positioned centrally on the tibial plateau, and there has been nominal progression of the degenerative joint disease affecting the stifle.
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case_images: fig9
case_images: The previously noted thickening of the right patellar tendon had resolved, although there was mineralization of the distal portion of the tendon (Figures 9(a) and 9(b)).