Thoracolumbar Spinal Stabilization with Three Dimensional-Printed Drill Guides and Pre-Contoured Polyaxial Bone Plates.

OBJECTIVE: The aim of this study was to report new preoperative and intraoperative techniques performed for canine thoracic or lumbar spine kyphosis stabilization using three-dimensional-printed patient-specific drill guides, polyaxial titanium bone plates and drill stops, and to determine the accuracy of screw placement using these techniques. STUDY DESIGN: Retrospective study, five client-owned dogs. RESULTS: Three-dimensional-printed patient-specific drill guides and drill stops allowed safe drilling and screw placement in all of the cases, with (i) 84% of the screws graded as I (ideal placement) and 16% as IIa, IIIa or IIIb according to the modified Zdichavsky classification (partial penetration of medial pedicle wall, partial penetration of lateral pedicle wall and full penetration of lateral pedicle wall respectively), (ii) mean mediolateral deviation of ± 4.06 degrees (standard deviation: 8.21 degrees) compared to planned trajectories and (iii) variation in screw depth of ± 2.29mm (standard deviation: 3.07mm) compared to planned depth. CONCLUSION: We believe that the techniques presented here for thoracic spinal stabilization in dogs show promise; they allowed safe placement of screws along planned trajectories and depth; they also removed the need to use polymethylmethacrylate, while the use of titanium offers the possibility to repeat magnetic resonance imaging in these cases with chronic spinal conditions.

A 3-Dimensional Printed Patient-Specific Surgical Guide to Facilitate Transsphenoidal Hypophysectomy in Dogs.

Objective: Hypophysectomy in dogs is a difficult surgery that requires specific learning and training. We aimed to evaluate the accuracy of a 3-dimensional printed patient-specific surgical guide to facilitate choosing the entry point in the basisphenoid bone before approaching the sella turcica during transsphenoidal hypophysectomy in dogs. Methods: Two canine cadavers and 8 dogs undergoing transsphenoidal hypophysectomy for Cushing's disease treatment, involving design and fabrication of a 3-dimensional printed guide. The ideal entry point in the basisphenoid bone outer cortical layer was determined in each dog pre-operatively; its anatomical location was described with a set of measurements then compared to post-operative computed tomography measures describing the location of the outer cortical window created in the basisphenoid bone. Results: Several guide designs were proposed, and a consensus reached based on surgeons' experience performing hypophysectomy. The device chosen could be applied to the size and shape of skulls encountered in this case series. The pre-planned measurements were comparable to post-operative measurement (there was also no statistical difference), with median of differences <0.1 mm, which we judged as clinically acceptable. Clinical Significance: Hypophysectomy in dogs is a challenging procedure that has a learning curve and needs to be performed by specialist neurosurgeons. We propose that a low-profile 3-dimensional printed surgical guide can aid the specialist neurosurgeon to locate the burring site of the outer cortical layer of the basisphenoid bone at a pre-defined location and with good accuracy. It does not alleviate the need to understand the anatomy of the region and to know how to create a slot within the basisphenoid bone, which remains essential to enter the sella turcica. This device could help specialist veterinary neurosurgeons wishing to be trained to perform hypophysectomy.

Development of a Novel Medial Synoviocentesis Approach to the Bicipital Bursa in an Equine Cadaver Model.

OBJECTIVE: To describe the volume and dimensions of the bicipital bursa and its position in relation to bony and soft tissue structures, in order to develop a novel medial synoviocentesis approach to the bicipital bursa. STUDY DESIGN: Cadaveric study. ANIMALS: Adult equine cadaver limbs (n=19). METHODS: Bicipital bursa dimensions, volume, and relationship to bony structures were obtained from positive contrast computed tomography images after distension of the bursa (n=7). Following an intra-bursal injection of polyurethane resin, the bicipital bursa (n=4) was dissected and its relationship to soft tissue structures described. After computed tomography and dissection, a novel medial bicipital bursocentesis approach was investigated on intact cadavers (n=8). RESULTS: Median (range) of measurements were: length 9.02 cm (8.48-9.45 cm); width 7.06 cm (6.71-8.01 cm); and volume 51 mL (45-58 mL). The medial aspect of the bicipital bursa was located at the junction of the subclavius and biceps muscles, which corresponds with the externally visible lateral pectoral sulcus. Needle insertion 5-10 mm craniolateral to the center of the lateral pectoral sulcus midway between the palpable distal aspect of the deltoid tuberosity and the cranial part of the greater tubercle was found to be a reliable landmark for the novel medial bursocentesis approach. This approach was successful in all cadavers. CONCLUSION: The novel approach to the bicipital bursa provided access to the medial aspect of the bursa and is an alternative to the lateral approaches. Further validation in live horses is warranted to establish the safety and efficacy of this technique.