Objective
To determine the influence of a purpose‐built frame on the accuracy of screw placement during computer‐assisted orthopedic surgery (CAOS) of the equine extremity.
Study design
Experimental ...cadaveric study.
Sample population
Twenty‐four paired equine cadaveric limbs obtained from seven horses.
Methods
Three 4.5‐mm cortex screws were inserted in lag technique in three different planes of orientation in the proximal phalanx (P1) by means of CAOS. In the study group (n = 12 limbs), the tracker was anchored on a purpose‐built frame designed to stabilize the extremity. In the control group (n = 12 limbs), a conventional tracker array was used that was anchored directly on P1. The stability of both tracker arrays was assessed during the procedure by using fiducial markers. After screw placement, preoperative and postoperative computed tomographic images were assessed to measure surgical accuracy aberrations (SAA) between the planned and achieved screw position. Descriptive statistics and repeated‐measures analysis of variance were performed to compare SAA measurements between the study and control group.
Results
Both tracker arrays remained consistently stable in all specimens. Mean overall SAA of screw insertion were lower in the study group (0.7 mm; median, 0.5; range 0‐3.4) than in the control group (1.2 mm; median, 0.9; range, 0‐4.2 mm).
Conclusion
The mean SAA achieved in cortex screw placement using CAOS lies within the range of approximately 1 mm. The use of a purpose‐built frame avoided additional drilling of the target bone and improved surgical accuracy compared with the conventional tracker array.
Clinical significance
The purpose‐built frame described in this report can be used to facilitate CAOS in equine orthopedics without compromising surgical accuracy.
Objective
To describe clinical applications of computer‐assisted orthopedic surgery (CAOS) in horses with a navigation system coupled with a cone beam computed tomography unit.
Study design
...Retrospective clinical case series.
Animals
Thirteen adult horses surgically treated with CAOS.
Methods
Medical records were searched for horses that underwent CAOS between 2016 and 2019. Data retrieved included signalment, diagnosis, lameness grade prior to surgery, surgical technique and complications, anesthesia and surgery time, and information pertaining to the perioperative case management and outcome.
Results
In 10 cases, surgical implants were placed in the proximal phalanx, third metatarsal bone, ulna, or medial femoral condyle. In one case, navigated transarticular drilling was performed to promote ankylosis of the distal tarsal joints. In another case, an articular fragment of the middle phalanx was removed with the help of CAOS guidance. In the final case, a focal osteolytic lesion of the calcaneal tuber was curetted with the aid of CAOS. In seven cases, a purpose‐built frame was used for the surgical procedure. All surgeries were performed successfully and according to the preoperative plan.
Conclusion
Computer‐assisted orthopedic surgery can be an integral part of the clinical case management in equine surgery. To optimize workflow and time‐efficiency, the authors recommend designating one team for operative planning and another for the execution of the surgical plan. Specialized equipment, such as the purpose‐built frame, will further improve CAOS applications in equine surgery.
Clinical significance
After they have become familiar with the operational principles, equine surgeons can readily apply CAOS for a broad spectrum of indications.
Summary
A 3‐year‐old Comptois gelding with a history of chronic fistulation at the base of the right ear was referred for the treatment of a unilateral ectopic tooth in the right temporal region. ...Cone‐beam computed tomography (CBCT) confirmed the presence of an ectopic tooth in the right mandibular fossa. The ectopic tooth was associated with a draining tract running through the zygomatic process of the right temporal bone. A total mandibular condylectomy provided a direct approach to the ectopic tooth, which was subsequently successfully removed. Long‐term follow‐up confirmed a satisfactory outcome despite the need for repeated debridement and persistence of a small draining tract 15 months postoperatively. Computer‐assisted surgery (CAS) provided precise anatomical intraoperative orientation for the condylectomy and subsequent removal of the ectopic tooth close to the calvarium. The use of CAS greatly facilitated surgery and minimised the risks of important collateral damage.
To develop a minimally invasive technique for placing a toggle construct across the coxofemoral joint of small equids using computer-assisted surgery.
Experimental cadaveric study.
Three pilot ...specimens: One donkey, one Shetland pony and one Warmblood foal. Six main study specimens: Three Shetland ponies, one American Miniature Horse, one Warmblood foal and one donkey.
Experimental surgeries were performed on both coxofemoral joints of each cadaver. Using a minimally invasive surgical approach, 5.5 mm bone canals were drilled through the femur and acetabulum, traversing the coxofemoral joint. Intraoperative guidance was provided by a cone-beam computed tomography (CBCT)-coupled surgical navigation system. A toggle construct was introduced through the bone canals. Surgical accuracy aberrations (SAA) were measured at the femoral entry and exit points and at the acetabular entry point on merged pre- and postoperative CBCT scans. The coxofemoral joint was assessed for articular cartilage damage by gross dissection.
A toggle construct was placed across all 18 coxofemoral joints. The overall median SAA in the main study was 2.8 mm (range: 0.4-8.0 mm). No cartilage damage was found in the cadaveric specimens of the main study.
The described technique allowed for the placement of a toggle construct across the coxofemoral joint of small equid cadaveric specimens without prior coxofemoral luxation.
This technique may serve as an option for surgical stabilization of coxofemoral joints in small equids. Further biomechanical investigations are required to assess optimal implant positioning and toggle constructs.
A 16-year-old warmblood mare was referred with a progressive history of behavioral changes and left-sided blindness. Following neuroanatomical localization to the forebrain, magnetic resonance ...imaging of the head revealed a well-delineated, 4.5 cm in diameter, round pituitary mass causing marked compression of the midbrain and optic chiasm. Euthanasia was recommended but declined by the owners. Veterinary specialists and a human neurosurgeon collaboratively prepared for surgical case management. A novel navigated transmandibular lateral transsphenoidal approach was developed to access the region of the sella turcica and practiced on cadaver specimens. The horse was anesthetized and placed in sternal recumbency with the head above the heart line. Using a cone beam computed tomography (CBCT)-coupled navigation system, a navigated pin traversing the vertical ramus of the mandible and the lateral pterygoid muscle was placed in a direct trajectory to the predetermined osteotomy site of the basisphenoid bone. A safe corridor to the osteotomy site was established using sequential tubular dilators bypassing the guttural pouch, internal and external carotid arteries. Despite the use of microsurgical techniques, visualization of critical structures was limited by the long and narrow working channel. Whilst partial resection of the mass was achieved, iatrogenic trauma to the normal brain parenchyma was identified by intraoperative imaging. With consent of the owner the mare was euthanized under the same general anesthesia. Post-mortem magnetic resonance imaging and gross anatomical examination confirmed partial removal of a pituitary adenoma, but also iatrogenic damage to the surrounding brain parenchyma, including the thalamus.
Introduction Equine trigeminal-mediated headshaking is a painful neuropathic disorder comparable to trigeminal neuralgia in humans. The selective destruction of pain fibers within the trigeminal ...ganglion, called rhizotomy, is the surgical treatment of choice for idiopathic trigeminal neuralgia refractory to medical treatment in humans. The human trigeminal ganglion is enclosed by a dural recess called the Meckel’s or trigeminal cave, in which the ganglion is surrounded by a cerebrospinal fluid (CSF)-filled subarachnoid space. During glycerol rhizotomy, glycerol is percutaneously injected in this CSF-filled space. Until now, information about the anatomy of the dural recess and the subarachnoid space surrounding the trigeminal ganglion is lacking in horses. The aim of this study was to explore if a CSF-filled subarachnoid space around the trigeminal ganglion exists in horses. Materials and methods Six equine cadaver heads were investigated for CSF accumulation around the ganglion with a 3 Tesla MRI. After anatomical dissection to expose the trigeminal root, a polymer-based radiopaque contrast agent was injected through the porus trigeminus into the subarachnoid space (cisternography). The exact delineation and the volume of the contrast agent accumulation were determined on subsequent micro-computed tomographic scans and segmentation. Finally, the distribution of the contrast agent within the subarachnoid space was examined histologically in three specimens. Results In all 12 specimens included in this study, the trigeminal ganglion was surrounded by a subarachnoid space forming a trigeminal cistern. The mean volume of the trigeminal cave in this study was 0.31 mL (±SD: 0.11 mL). Distribution of the contrast agent along the peripheral nerves (i.e., ophthalmic, maxillary and/or mandibular nerve) was observed in 7 out of 12 specimens. Discussion/conclusion A subarachnoid space surrounding the trigeminal ganglion exists in the horse and could be targeted for glycerol rhizotomy in horses suffering from trigeminal-mediated headshaking. However, the clinical relevance of contrast agent distribution along the peripheral nerves remains to be assessed.
Recent breakthroughs in computer vision and natural language processing have spurred interest in challenging multi-modal tasks such as visual question-answering and visual dialogue. For such tasks, ...one successful approach is to condition image-based convolutional network computation on language via Feature-wise Linear Modulation (FiLM) layers, i.e., per-channel scaling and shifting. We propose to generate the parameters of FiLM layers going up the hierarchy of a convolutional network in a multi-hop fashion rather than all at once, as in prior work. By alternating between attending to the language input and generating FiLM layer parameters, this approach is better able to scale to settings with longer input sequences such as dialogue. We demonstrate that multi-hop FiLM generation achieves state-of-the-art for the short input sequence task ReferIt --- on-par with single-hop FiLM generation --- while also significantly outperforming prior state-of-the-art and single-hop FiLM generation on the GuessWhat?! visual dialogue task.
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