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During minimally invasive spinal surgery, correct identification of the affected intervertebral disc space is critical. Percutaneous palpation is commonly used, but results may be unreliable. Fluoroscopy is the gold standard but can be cumbersome and exposes operators to ionizing radiation. Spinal ultrasound has been described in veterinary medicine and could be a feasible alternative. This prospective, methods comparison study mimicked a minimally invasive spinal surgery in 10 canine cadavers and compared the accuracy of ultrasound and percutaneous palpation for thoracolumbar intervertebral disc space identification, using fluoroscopy as the reference standard. For each experiment, a disc space was randomly chosen. Identification was then attempted using both percutaneous palpation and ultrasound. For ultrasound, a linear probe was used to guide the operator to the correct location. The time necessary to perform each method was recorded. Accuracies for each method were calculated and statistically compared. Effects of body condition score, location of the targeted thoracolumbar intervertebral disc space and learning curve for each method were also evaluated. Ultrasonographic identification was more accurate (96.7% vs. 76.7%; P < 0.03) but took longer (147 s vs. 29 s; P < 0.0001) than percutaneous palpation. Findings from this cadaver study indicated that percutaneous palpation alone had low accuracy for correctly identifying a targeted thoracolumbar intervertebral disc space and supported the use of ultrasound as a method for improving the accuracy. Future studies are needed to assess the method in clinical cases, especially in obese dogs and/or those in which the targeted site is distant from palpable anatomical landmarks. [ABSTRACT FROM AUTHOR]

ABSTRACT Tissue-engineered constructs (TECs) combining resorbable calcium-based scaffolds and mesenchymal stem cells (MSCs) have the capability to regenerate large bone defects. Inconsistent results have, however, been observed, with a lack of osteoinductivity as a possible cause of failure. This study aimed to evaluate the impact of the addition of low-dose bone morphogenetic protein-2 (BMP-2) to MSC-coral-TECs on the healing of clinically relevant segmental bone defects in sheep. Coral granules were either seeded with autologous MSCs (bone marrow-derived) or loaded with BMP-2. A 25-mm-long metatarsal bone defect was created and stabilized with a plate in 18 sheep. Defects were filled with one of the following TECs: (i) BMP ( n = 5); (ii) MSC ( n = 7); or (iii) MSC-BMP ( n = 6). Radiographic follow-up was performed until animal sacrifice at 4 months. Bone formation and scaffold resorption were assessed by micro-CT and histological analysis. Bone union with nearly complete scaffold resorption was observed in 1/5, 2/7, and 3/6 animals, when BMP-, MSC-, and MSC-BMP-TECs were implanted, respectively. The amount of newly formed bone was not statistically different between groups: 1074 mm3 [970-2478 mm3], 1155 mm3 [970-2595 mm3], and 2343 mm3 [931-3276 mm3] for BMP-, MSC-, and MSC-BMP-TECs, respectively. Increased scaffold resorption rate using BMP-TECs was the only potential side effect observed. In conclusion, although the dual delivery of MSCs and BMP-2 onto a coral scaffold further increased bone formation and bone union when compared to single treatment, results were non-significant. Only 50% of the defects healed, demonstrating the need for further refinement of this strategy before clinical use. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2637-2645, 2017. [ABSTRACT FROM AUTHOR]