34th Annual Scientific Meeting proceedings

The correction of spinal deformities is a challenging endeavor—not only due to the complexity of the surgical procedures involved but also because postoperative outcomes are often unpredictable.

Dorsal Techniques
Early techniques for correcting spinal deformities primarily involved decompression, followed by stabilization of the affected segments using threaded pins or Kirschner wires embedded in polymethyl methacrylate (PMMA). These methods achieved relatively favorable outcomes in limited case series, with 8 out of 12 dogs regaining normal neurological function in the long term (Aikawa 2007; Jeffery 2007). In a more recent study, neurological deterioration occurred in 5 of 6 dogs, with only one regaining normal neurological function postoperatively (Picon 2025). However, notable drawbacks include postoperative neurological deterioration following dorsal decompression and the blind trajectory of implant insertion into the vertebral bodies.

Similarly, dorsal laminectomy alone has been used to decompress the spinal cord, with disappointing results—9 of 11 dogs experienced postoperative deterioration, and only 1 regained normal neurological function (Picon 2025).

A segmental stabilization approach, with or without decompression, was applied in a case series of 9 dogs. Long-term improvement was observed in 8 dogs, 4 of which achieved a normal gait. Postoperative complications occurred in 3 dogs, and one dog deteriorated to non-ambulatory paraparesis 3.5 years post-surgery (Charalambous 2014).

Recent advancements include the use of patient-specific drill guides created from 3D computer reconstructions of the malformed vertebrae. These biocompatible resin guides are molded to the dorsal vertebral surface and enable safe, bilaterally directed drilling through the pedicles, minimizing the risk of iatrogenic damage and avoiding canal violation or contralateral corridor interference. These corridors allow placement of cortical screws, which can then be embedded in PMMA (Violini 2024), affixed with a precontoured polyaxial bone plate (Gilman 2023), or anchored using a 3D-printed titanium plate (Guirguis 2024). Of 20 dogs treated with the PMMA technique, 4 showed immediate postoperative deterioration. In a long-term follow-up using owner questionnaires, 7 of 10 dogs exhibited an abnormal gait, with 3 improving, 6 remaining static, and 1 deteriorating. In 5 dogs treated with the contoured plate, 4 experienced no postoperative ataxia, and the single case of deterioration was due to recurrence of a subarachnoid diverticulum, which was addressed with durotomy and marsupialization at the time of stabilization. The primary advantage of 3D-printed drill guides is improved bone purchase through safe, preplanned pedicle drilling, compared to freehand techniques (Mullins 2023).

A single case report described the use of a complex assembly of rods and 3D-printed titanium "spinal covers" applied bilaterally to anchor the dorsal lamina and rib heads from T6–T7 following dorsal laminectomy. Traction applied during surgery reduced the Cobb angle from 76.5º to 62.7º (Kimura 2021). Although the dog initially deteriorated postoperatively, it regained normal neurological function within 12 months, despite a subsequent Cobb angle of 68.1º.

All these techniques address myelopathy through direct decompression or stabilization of suspected instability leading to progressive deterioration. However, only the use of spinal covers aimed to correct the vertebral malformation itself, attempting to realign the spinal column as done in human medicine.

Ventral Techniques
A case series involving 6 pugs used 3D reconstructions of the malformed segments to precontour two String-of-Pearls (SOP) plates, which were applied via a bilateral transthoracic approach. Postoperatively, 5 dogs had mild and inconsistent ataxia, while 1 showed persistent, consistent ataxia in the long term (Mathiesen 2018).

In another case, a 3.5-month-old Labrador Retriever underwent a left T3–T4 intercostal approach for decompression and stabilization of severe T2–T5 kyphosis. Partial corpectomies of T3–T4 were performed using a high-speed drill for ventral decompression, and 1.5 mm pins were placed in T2 and T5 vertebral bodies for stabilization. Although the dog deteriorated initially, it recovered the ability to walk and led a normal life by 10 months of age, with residual Horner’s syndrome.

More recently, a ventral realignment technique has been reported. Originally developed by Dr. Baroni, this method employs a left intercostal approach between the affected vertebrae to distract, partially realign, and stabilize the segment using cortical screws and PMMA, without requiring direct decompression (Farre 2021; Picon 2024). Advanced imaging allows precise planning of angles, lengths, and implant trajectories. The approach offers direct visualization of the vertebral bodies, aorta, and lungs, reducing the risk of iatrogenic injury. Using a Caspar retractor, traction is applied to achieve partial realignment, which indirectly decompresses the spinal cord (Moissonier 2011). Cortical screws are placed into the vertebral bodies, with their heads and proximal threads embedded in bone cement. No immediate postoperative neurological deterioration was observed. All dogs, except one that died the day after surgery, showed neurological improvement. Long-term follow-up of 44 combined cases reported normal neurological function in 34 dogs (77%), with one postoperative death, one euthanasia despite improvement, two lost to follow-up, and six dogs remaining at a Modified Frankel Score (MFS) of 4.

Among all surgical approaches for spinal deformity correction, ventral realignment appears superior in achieving long-term neurological improvement, despite being technically demanding. Correcting the malformation and restoring spinal alignment resulted in more frequent return to normal function in the largest reported series, with fewer instances of immediate postoperative decline. The integration of 3D technology further enhances surgical safety and precision, suggesting that the combination of spinal realignment and stabilization using printed materials warrants continued investigation.