Biomechanical Comparison of Double 2.3-mm Headless Cannulated Self-Compression Screws and Single 3.5-mm Cortical Screw in Lag Fashion in a Canine Sacroiliac Luxation Model: A Small Dog Cadaveric Study.

OBJECTIVE: The aim of this study was to evaluate the feasibility of safe positioning of double 2.3-mm headless cannulated self-compression screws (HCS) in a small dog cadaveric sacroiliac luxation model and to compare the static rotational biomechanical properties of fixation repaired using two different screw systems with a minimally invasive osteosynthesis technique: double 2.3-mm HCS and a single 3.5-mm standard cortical screw placed in a lag fashion. STUDY DESIGN: A unilateral small dog sacroiliac luxation model was stabilized using double 2.3-mm HCS (n = 11) or a single 3.5-mm cortical screw (n = 11). Radiographic and computed tomography (CT) imaging analyses and biomechanical testing of rotational force on the sacroiliac joint of both fixations were performed. The maximum load at failure and failure modes of each fixation were recorded and compared. RESULTS: Fluoroscopically guided percutaneous application of double HCS was safe in a unilateral sacroiliac luxation model in small dogs without violation of the vertebral and ventral sacral foramen. Furthermore, resistance to rotational force applied on fixation of the sacroiliac joint repaired with double 2.3-mm HCS estimated by maximum failure load was significantly higher than that of a single 3.5-mm cortical screw (p < 0.001). CONCLUSION: Although this was an experimental cadaveric study, based on our results, the use of smaller double HCS may be beneficial as an alternative to the conventional single lag screw for stabilization of sacroiliac luxation in small dogs.

Whole Blood Viscosity Reference Intervals and Its Correlation with Hematology and Serum Chemistry in Cats Using Scanning Capillary Method.

Whole blood viscosity, a hemorheological factor, is currently used for diagnosis, as it is correlated with various vascular diseases that are difficult to diagnose early with a general blood test. It was determined that it was necessary to set reference intervals for further studies and utilization of whole blood viscosity in cats, a representative companion animal, and this study was conducted. Fifty healthy cats were recruited for the study, and whole blood viscosity, complete blood count, and serum chemistry tests were performed. The reference intervals of whole blood viscosity were 15.169 to 43.684 cP at a shear rate of 1 s-1 reflecting diastole, and 3.524 to 5.544 cP at a shear rate of 300 s-1 reflecting systole. Red blood cells, hematocrit, hemoglobin, white blood cells, and neutrophils in the complete blood count, and total protein, albumin, globulin, and cholesterol in the serum chemistry were significantly correlated with whole blood viscosity. The results of this study set the reference intervals of whole blood viscosity for healthy cats in a wide shear rate range that has not yet been fully established, and its correlation with other blood indicators investigated.

Stifle Joint Arthrodesis for Treating Chronic-Osteoarthritis-Affected Dogs.

A two-year-old male Pomeranian dog was presented to a veterinary hospital due to the side effects of a surgical correction for patellar luxation. Stifle joint arthrodesis (SJA) was performed on the patient's right leg using autologous bone-grafting techniques. The right femur and tibial joint were angled 120-130°, and an SJA plate was fixed on the front of the two bones. After performing joint fusion of the right limb, medial-patellar-luxation-(MPL)-corrective surgery was performed to cut the tibial tuberosity on the left leg, and the fixing force was increased using the figure-of-eight-tension-band-wiring technique. Results were recorded regarding the dog's ability to walk and trot in the right hind limb; these results were evaluated for 27 days after surgery. It was difficult for the patient to walk because weight-bearing had not been carried out for 3 days after the surgery; short strides and partial weight bearing were possible 5 to 7 days after surgery. After 10 days, the patient was able to move while bearing weight with a slight disruption. With regard to trotting, the patient showed intermittent normal steps 5 to 7 days after surgery, but the disruption continued. After 14 days, trotting was possible, and it was observed that movement could be maintained during everyday activities.

Use of Computed Tomography and Magnetic Resonance Angiograms Combined with a 3D Surgical Guide in an Elderly Cat with an Occipital Lobe Meningioma.

We present a case of occipital lobe meningioma resection in an elderly cat. The surgery was performed with the goal of avoiding major bleeding. An 11-year-old castrated indoor-only male Persian Chinchilla (5.5 kg) was presented with a month-long history of progressive tetraparesis for a left occipital lobe meningioma. Magnetic resonance imaging revealed a T2-weighted heterogeneously hyperintensity and a T1-weighted well-contrast enhancing extradural mass in the left occipital lobe of the brain. Cerebral angiographic data were obtained using magnetic resonance (MRA) and computed tomography angiography (CTA). Advanced angiograms and virtual reconstruction of images revealed that the tumor was surrounded by the caudal parasagittal meningeal vein. A left caudal rostrotentorial craniotomy and en bloc resection of the tumor were performed, and histopathology revealed a meningioma. Complete neurological recovery was achieved within 10 days after surgery. To the best of our knowledge, this is the first case report describing CTA and MRA findings and favorable clinical outcomes after surgical management of a brain meningioma without severe perioperative complications.

Biomechanical Comparison between Inverted Triangle and Vertical Configurations of Three Kirschner Wires for Femoral Neck Fracture Fixation in Dogs: A Cadaveric Study.

The purpose of this study was to compare single-cycle axial load and stiffness between inverted triangle and vertical configurations of three Kirschner wires (K-wires) for femoral neck fracture fixation in small dog cadaveric models. In each of the eight cadavers, the basilar femoral neck fracture model was prepared on both sides of the femur. One side of the femur was stabilized with three 1.0 mm K-wires of an inverted triangle configuration (group T), and the other femur was stabilized with a vertical configuration (group V). Postoperatively, the placement of the K-wires was evaluated with radiographic and computed tomography (CT) images, and static vertical compressive loading tests were performed. The mean yield load and the lateral spread were significantly higher in group T compared to group V (p = 0.023 and <0.001). On the cross-section of femoral neck at the level of the fracture line, the surface area between K-wires was significantly larger (p < 0.001) and the mean number of cortical supports was significantly higher in group T (p = 0.007). In this experimental comparison, the inverted triangle configuration of three K-wires was more resistant to failure under axial loading than the vertical configuration for canine femoral neck fracture fixation.

Endoscopy-assisted resection of a sphenoid-wing meningioma using a 3D-printed patient-specific pointer in a dog: A case report.

A 9-year-old female mixed-breed dog presented for treatment of a presumed sphenoid-wing meningioma. Clinical signs included tonic-clonic seizures lasting <1 min, which had started 3 months previously. The physical examination results were unremarkable. An eccentrically located neoplastic cystic structure in the right sphenoid bone region suggestive of a meningioma and peritumoural brain oedema was observed in pre-operative magnetic resonance imaging (MRI). Prior to surgery, a three-dimensional (3D) patient-specific pointer (PSP) was designed using computed tomography (CT) images and computer-aided 3D design software. After a targeted approach and exposure of the lateral part of the right temporal lobe by a craniectomy guided by the 3D-PSP, complete macroscopic piecemeal resection of the meningioma could be performed using endoscopy-assisted brain surgery. Post-operative MRI confirmed complete excision of the tumor. Anticonvulsive therapy was discontinued after 90 days, and the dosage of anticonvulsants was tapered 2 weeks after surgery. At a follow-up examination 225 days post-operatively, recurrence of seizures was not observed, and the absence of tumor recurrence was confirmed by a repeat MRI examination. To the best of our knowledge, this is the first report in veterinary medicine describing a successful resection of a sphenoid-wing meningioma using a 3D-PSP. 3D-PSP-assisted craniectomy may be a surgical option for some canine skull-based tumors, such as sphenoid wing meningiomas.

Case report: Block recession calcaneoplasty of the calcaneal tuber for treating lateral superficial digital flexor tendon luxation in a dog.

A 4-year-old, intact, female, Collie was presented with 5 month history of right hindlimb lameness. Lateral luxation of the superficial digital flexor tendon (SDFT) was diagnosed on the basis of the clinical, radiographic and ultrasonographic finding. Intraoperatively, shallow right calcaneal tuber was observed. Block recession calcaneoplasty with retinaculum repair using anchor screw were performed to manage SDFT luxation. Additionally, temporary restraining pin was placed on lateral aspect of the calcaneal tuber. The patient demonstrated mild lameness at 2 weeks postoperatively and improved to normal limb function at 12 weeks postoperatively. As the gold standard of surgical techniques for SDFT luxation has not yet been reported, block recession calcaneooplasty may be an alternative surgical option for patients with calcaneal morphologic abnormalities causing SDFT luxation.

Case report: Three-dimensionally printed patient-specific acetabular cage for revision surgery of aseptic loosening in a dog with micro total hip replacement.

A 2-year-old castrated male Pomeranian dog was presented for regular follow-up after micro total hip replacement (mTHR) 16 months prior to presentation. Clinically, the dog did not show any noticeable lameness of the left hindlimb, except for external rotation during walking. However, radiographic findings, namely rotation and medialization of the acetabular cup with a periprosthetic lucent line and bone formation medial to the acetabulum, were interpreted as aseptic loosening of the acetabular component. Because the dog was incompatible with the conventional THR revision method owing to severe bone defects in the acetabulum, a patient-specific titanium acetabular cage prosthesis with biflanges and four cranial and one caudal screw hole was designed for revision surgery. A custom-made acetabular cage was prepared, and it had a 12-mm polyethylene cup fixed with polymethylmethacrylate bone cement and positioned in the acetabulum. After the custom-made acetabular cage was anchored to the pelvic bone with the five cortical screws, reduction of the prostheses was achieved smoothly. The dog showed almost normal limb function without external rotation of the left hindlimb 2 weeks postoperatively. Bone remodeling and stable implant position were noted on radiographic images 3 years after revision surgery, with no evidence of loosening. Based on the clinical outcomes, the use of a custom-made acetabular prosthesis can be an effective treatment option for revision arthroplasty in acetabula with severe bone loss and structural changes in small-breed dogs.

Multiple Meningioma Resection by Bilateral Extended Rostrotentorial Craniotomy with a 3D-Print Guide in a Cat.

A 13-year-old castrated male domestic shorthair cat was referred for the surgical removal of multiple meningiomas. The cat experienced generalized tonic-clonic seizures, altered mentation, mild proprioceptive ataxia, and circling. Magnetic resonance imaging (MRI) revealed two round, solitary, well-delineated, space-occupying lesions suggestive of multiple meningiomas in the right frontal and occipital lobes. Before surgery, patient-specific three-dimensional (3D) printed models and guides were produced using a 3D program based on MRI and computed tomography (CT), and a rehearsal surgery was performed. With a 3D guide to find the location of the craniotomy lines, bilateral extended rostrotentorial craniotomy allowed en bloc resection of multiple meningiomas. The bone fragment was replaced and secured to the skull with a craniofacial plate and screws with an artificial dura. All of the surgical steps were performed without complications. The preoperative presenting signs were resolved by the time of follow-up examinations 2 weeks after surgery. Twelve months after the removal of the multiple meningiomas, the cat survived without further neurological progression. For the resection of multiple meningiomas, surgery can result in large bone defects and risk of massive hemorrhage. For this challenging surgery, patient-specific 3D models and guides can be effective for accurate and safe craniotomies.

Novel transforaminal approach allows surgical decompression of an atlantoaxial band in dogs: a cadaveric study and clinical cases.

OBJECTIVES: To describe a novel transforaminal approach for surgical excision of the atlantoaxial (AA) band and examine its feasibility, safety, and mechanical advantages in an ex vivo study and clinical cases. SAMPLES: 26 canine cadavers and 2 canine patients with AA bands. PROCEDURES: The transforaminal approach via the first intervertebral foramen was designed to avoid damaging the dorsal AA ligament (DAAL) and dorsal laminas to maintain joint stability. The cadaveric study started on December 2020 and lasted 3 months. The ligamentum flavum (LF) was removed using a novel approach; then, gross examination was conducted to verify the potential damage to the spinal cord and associated structures and the adequacy of LF removal. Subsequently, the ex vivo tension test of the DAAL was conducted to establish whether the approach induced mechanical damage to the ligaments. Finally, 2 dogs diagnosed with an AA band were surgically treated with the transforaminal approach. RESULTS: In the cadaveric study, postsurgical evaluation verified the subtotal removal of LF without damage to the dura mater. There were no significant differences in the mechanical properties of the DAAL, including the ultimate strength (P = .645) and displacement (P = .855), between the surgical and intact groups during the ex vivo tension test. In clinical cases, clinical signs and neurologic grades improved until the final follow-up. CLINICAL RELEVANCE: The described surgical procedure using a transforaminal approach appears to sufficiently permit the removal of an AA band while reducing damage to the DAAL and spinal cord. Our study highlights the feasibility of the transforaminal approach.

Case report: Primary chronic calcaneal bursitis treated with subtotal bursectomy in a cat.

A 6-year-old, female spayed Bengal cat with a bodyweight of 6.4 kg was presented with swelling of the bilateral calcaneal region and weight-bearing hindlimb lameness with a 4-month history of unsuccessful conservative therapy. On orthopedic examination, a cyst-like mass around the calcaneal tendon was palpated. Palpating the mass and flexing the tarsal joint triggered pain. Through ultrasonography and magnetic resonance imaging, an inflamed or fluid-accumulated lesion was suspected around the calcaneal tendon, but there was no evidence of calcaneal tendonitis. Swollen calcaneal bursae were removed surgically. Histopathologic examination revealed fibrosis and an edematous feature. The cat was diagnosed with bilateral chronic primary calcaneal bursitis based on history, clinical signs, and diagnostic results. Hence, subtotal bursectomy was performed. At 4 weeks postoperatively, the cat had no pain around the tarsal joints and was ambulating normally. Radiographic and ultrasonographic exams revealed no recurrence of swelling or inflammation in the calcaneal region. Thirteen-month follow-up confirmed acceptable function and no relapse of clinical signs. The inflammation of calcaneal bursa alone can be the primary cause of hindlimb lameness in cats. A cat with hindlimb lameness and swelling on the calcaneal region should be assessed with the possibility of primary calcaneal bursitis. Subtotal calcaneal bursectomy can be considered as an effective treatment for primary chronic bursitis.

Epineural Neurorrhaphy of a Large Nerve Defect Due to IatroGenic Sciatic Nerve Injury in a Maltese Dog.

Epineural neurorrhaphy is a standard nerve repair method, but it is rarely reported in veterinary literature. Epineural neurorrhaphy in canine sciatic nerve injury are described in this report. An 11-month-old, castrated male Maltese dog, presented with an one-month history of non-weight bearing lameness and knuckling of the right pelvic limb. The dog showed absence of superficial and deep pain perception on the dorsal and lateral surfaces below the stifle joint. The dog had undergone femoral head and neck osteotomy in the right pelvic limb one month prior to referral at a local hospital. Based on physical and neurological examinations, peripheral nerve injury of the right pelvic limb was suspected. Radiography showed irregular bony proliferation around the excised femoral neck. Magnetic resonance imaging revealed sciatic nerve injury with inconspicuous continuity at the greater trochanter level. A sciatic nerve neurotmesis was suspected and surgical repair was decided. During surgery, non-viable tissue of the sciatic nerve was debrided, and epineural neurorrhaphy was performed to bridge a large, 20-mm defect. The superficial and deep pain perception was progressively improved and restored at 3 weeks postoperatively, and the dog exhibited a gradual improvement in motor function. At 10 weeks postoperatively, the dog showed no neurological deficit including knuckling but the tarsal joint hyperextension did not improve due to ankylosis. The dog had undergone tarsal arthrodesis and exhibited almost normal limb function without any neurologic sequela until the last follow-up at 2.5 years postoperatively.

Pelvic Endoprosthesis after Hemipelvectomy Using a 3D-Printed Osteotomy Guide for Infiltrative Osteoma in a Cat.

With the development of 3D printing and surgical techniques, various defect reconstruction methods after tumor resection have been applied not only in humans but also in veterinary medicine. This report describes a case of reconstruction after hemipelvectomy for an osteoma in a cat using a 3D-printed pelvic endoprosthesis and micro total hip replacement (mTHR). A 5-year-old spayed female Turkish Angora cat was referred for a 1-month history of constipation and intermittent weight-bearing lameness in the left hindlimb. An osteoma in the pelvis measuring 4.5 × 3 × 5.4 cm was identified based on diagnostic examinations. A left mid-to-caudal partial and right caudal partial hemipelvectomy, and a left femoral head and neck osteotomy, were planned to remove the mass. Reconstruction of the bone defect using 3D-printed metal endoprosthesis and mTHR in the left hindlimb was intended. During right caudal partial hemipelvectomy, right femoral head and neck osteotomy was performed because there was infiltration in the medial wall of the acetabulum. Histopathological examination confirmed the diagnosis of an osteoma. Two weeks post-surgery, surgical debridement and femoral stem removal were performed because of delayed wound healing and sciatic neurapraxia, leading to femoral stem dislocation from the cup. The delayed wound healing and sciatic neurapraxia were appropriately addressed. The cat regained normal weight and defecation 4 weeks post-operatively. Two years post-surgery, the patient recovered with an almost normal gait. Hemipelvectomy with 3D-printed endoprosthesis provides a safe surgical option with favorable outcomes for neoplasms in the pelvis of cats.

Evaluation of the accuracy of three-dimensionally printed patient-specific guides for transsphenoidal hypophysectomy in small-breed dogs.

OBJECTIVE: To assess the accuracy of transsphenoidal hypophysectomy using 3-D printed patient-specific guides (3D-PSGs) in small-breed dogs. ANIMALS: Heads obtained from the cadavers of 19 small-breed dogs (ex vivo portion of study) and 3 healthy adult (3 to 4 years) purpose-bred Beagles with a median body weight of 9.2 kg. PROCEDURES: In the ex vivo study, CT images of the cadavers were collected. The position, width, and length of the pituitary fossa and the pilot hole (insertion angle and place) were measured. Using PSGs, 19 pilot holes were made for the pituitary gland fossa, and CT was performed to assess the position accuracy. In the in vivo study, 3 surgical windows from the pilot holes were made using PSGs. Repeated CT and MRI were performed to evaluate the safeness and effectiveness of PSGs, followed by necropsy. RESULTS: In the ex vivo study, the median (interquartile range) difference between the pre- and postoperative insertion angles was 2° (0° to 3.5°) and the median deviation of the pilot hole was 0.46 mm (0 to 1.58 mm). In the in vivo study, the surrounding structures were not damaged, and favorable outcomes were evident in terms of the shape, size, and position of the surgical window. CLINICAL RELEVANCE: 3D-PSGs provided a safe and effective surgical window for transsphenoidal hypophysectomy. Our findings emphasized the applicability of PSGs in brain surgery, in terms of accuracy and effectiveness.

Ischiocavernosus Muscle Release for Urethral Obstruction Treatment after Pelvic Symphyseal Distraction Osteotomy in a Cat with Pelvic Stenosis.

Symphyseal distraction osteotomy (SDO) with a polymethyl methacrylate (PMMA) spacer is an effective surgical treatment for cats with pelvic stenosis. This study reports the successful treatment of urethral obstruction due to ischiocavernosus muscle (IM) tension after SDO with a PMMA spacer. A 2-year-old castrated male Korean domestic shorthair feline had megacolon and pelvic canal stenosis. The ratio of the maximal diameter of the colon to the L5 length and the pelvic canal diameter ratio were 1.6 and 0.45, respectively. Pelvic SDO was performed with a PMMA spacer, leading to pelvic canal enlargement (pelvic canal diameter ratio: 0.73). Two days after surgery, dysuria was identified immediately after removing the preoperatively placed urinary catheter. Complete blood counts and serum biochemical profiles were within the reference intervals, and a positive contrast retrograde urethrogram confirmed urethral obstruction at the level of the membranous-pelvic urethra region. Increased tension of the IM leading to a narrowed urethra was suspected as the cause of urethral obstruction. After IM release at the level of origin on the ischium, the patient had an uneventful recovery with spontaneous urination. Muscle release resulted in excellent functional restoration, with no intraoperative or postoperative complications reported during the 12-month long-term follow-up. Therefore, SDO with IM release could be a feasible therapeutic option for severe pelvic stenosis without complications, such as urethral obstruction, in cats.