Clinical presentation, magnetic resonance imaging features, and outcome in 6 cats with lumbar degenerative intervertebral disc extrusion treated with hemilaminectomy.

OBJECTIVE: To describe the clinical presentation, magnetic resonance imaging features, and outcome of cats treated with hemilaminectomy for intervertebral disc extrusion (IVDE). STUDY DESIGN: Short case series. ANIMALS: Six cats. METHODS: Medical records were reviewed for signalment, onset, duration, and severity of clinical signs, magnetic resonance imaging features, surgical findings, and clinical outcome with a minimum postoperative follow-up of 4 weeks. RESULTS: Our population included 6 cats with a median age of 8.6 years, consisting predominantly of males (n = 5) and purebred cats (n = 4). An acute onset and short duration of progressive clinical signs of myelopathy was the most common presentation; spinal hyperesthesia was present in 3 cats. A large volume of extradural material was identified by MRI within the lumbar vertebral column of each cat, causing marked spinal cord compression. The most common sites affected were L2-L3 (n = 2) and L6-L7 (n = 2). Follow-up after hemilaminectomy was available in 5 cats: 4 had normal voluntary motor function, and 1 had recurrence of acute paraplegia, compromised nociception, and an extensive T2w hyperintense intramedullary lesion according to MRI. All 4 cats with preoperative urinary incontinence remained incontinent for at least 1 week despite good voluntary motor function of pelvic limbs. CONCLUSION: Intervertebral disc extrusion was diagnosed by MRI in all 6 cats, most commonly at L2-3 and L6-7. Hemilaminectomy resulted in a good to excellent outcome in 4 of 5 cats. CLINICAL SIGNIFICANCE: Feline IVDE can be diagnosed by MRI and carry a good prognosis after surgical decompression, although urinary continence may be delayed despite good pelvic limb voluntary motor function.

Accuracy of a patient-specific 3D printed drill guide for placement of cervical transpedicular screws.

OBJECTIVE: To develop a patient-specific 3-dimensional (3D) printed drill guide for placement of cervical transpedicular screws and to assess its accuracy. STUDY DESIGN: Prospective case-series. SAMPLE POPULATION: Thirty-two cervical pedicle screws (CPS) placed in 3 large breed dogs. METHODS: Computed tomographic (CT) data of the cervical vertebrae were exported to a medical image processing software and 3D virtual vertebral models were created for each vertebra. These models were processed in a computer aided design (CAD) software to determine the optimal trajectory and size of the CPS. Virtual drill guides were created for each patient, 3D-printed, and used intraoperatively. Locking titanium screw heads were bonded with polymethylmethacrylate cement to stabilize affected vertebral segments. Postoperative CT was used to assess the radiological accuracy of CPS placement in each dog. For each screw, CAD files were analyzed to determine a screw-diameter-to-pedicle-width-ratio (SDPWR) at the narrowest point of the pedicle. RESULTS: A total of 32 CPS were placed, measuring 3.5 mm (n = 20), 2.7 mm (n = 11), and 2.4 mm (n = 1) in diameter. The majority (29/32) of these screws were placed without evidence of vertebral canal breach (grade 0), whereas a vertebral canal breach <2 mm (grade 1) was detected in 3/32 screws. This outcome was achieved despite a mean SDPWR of 0.75 (range 0.58-0.93). CONCLUSION: The use of a 3D-printed patient-specific drill guide permitted accurate placement of 32 bicortical pedicle screws in the caudal cervical vertebrae of 3 dogs. This technique may improve clinical outcome through superior biomechanical properties of screws, reduced surgical time, and reduced morbidity. These results warrant evaluation of patient outcome in a larger population.