Nobuo Kanno

A Comparison of the Process of Remodeling of Hydroxyapatite/Poly-D/L-Lactide and Beta-Tricalcium Phosphate in a Loading Site

Currently, the most commonly used bioresorbable scaffold is made of beta-tricalcium phosphate (β-TCP); it is hoped that scaffolds made of a mixture of hydroxyapatite (HA) and poly-D/L-lactide (PDLLA) will be able to act as novel bioresorbable scaffolds. The aim of this study was to evaluate the utility of a HA/PDLLA scaffold compared to β-TCP, at a loading site. Dogs underwent surgery to replace a section of tibial bone with a bioresorbable scaffold. After the follow-up period, the scaffold was subjected to histological analysis. The HA/PDLLA scaffold showed similar bone formation and superior cell and tissue infiltration compared to the β-TCP scaffold, as seen after Villanueva Goldner staining. Moreover, silver staining and immunohistochemistry for Von Willebrand factor and cathepsin K demonstrated better cell infiltration in the HA/PDLLA scaffold. The fibrous tissue and cells that had infiltrated into the HA/PDLLA scaffold tested positive for collagen type I and RUNX2, respectively, indicating that the tissue and cells that had infiltrated into the HA/PDLLA scaffold had the potential to differentiate into bone. The HA/PDLLA scaffold is therefore likely to find clinical application as a new bioresorbable scaffold.

In vitro evaluation of the relationship between the semitendinosus muscle and cranial cruciate ligament in canine cadavers

OBJECTIVE To evaluate the role of the semitendinosus muscle in stabilization of the canine stifle joint. SAMPLE Left stifle joints collected from cadavers of 8 healthy Beagles. PROCEDURES Left hind limbs, including the pelvis, were collected. To mimic the tensile force of the quadriceps, gastrocnemius, and semitendinosus muscles, wires were placed under strain between the ends of each muscle. A sensor was used to measure the tensile force in each wire. Specimens were tested in the following sequence: cranial cruciate ligament (CrCL) intact, CrCL transected, released (tensile force of semitendinosus muscle was released in the CrCL-transected stifle joint), and readjusted (tensile force of semitendinosus muscle was reapplied in the CrCL-transected stifle joint). Specimens were loaded at 65.3% of body weight, and tensile force in the wires as well as the cranial tibial displacement were measured. RESULTS Tensile force for the CrCL-transected condition increased significantly, compared with that for the CrCL-intact condition. Mean ± SD cranial tibial displacement for the CrCL-transected condition was 2.1 ± 1.3 mm, which increased to 7.2 ± 2.3 mm after release of the tensile force in the semitendinosus muscle. CONCLUSIONS AND CLINICAL RELEVANCE Results supported the contention that the semitendinosus muscle is an agonist of the CrCL in the stifle joint of dogs. Moreover, the quadriceps and gastrocnemius muscles may be antagonists of the CrCL. These findings suggested that the risk of CrCL rupture may be increased by diseases (such as cauda equina syndrome) associated with a decrease in activity of the semitendinosus muscle.

A magnetic resonance imaging-based classification system for indication of trans-sphenoidal hypophysectomy in canine pituitary-dependent hypercortisolism

OBJECTIVES The objectives of this study were to establish a magnetic resonance imaging-based classification system for canine hyperadrenocorticism according to pituitary gland extension, determine indications for trans-sphenoidal hypophysectomy, and clarify the prognosis for each disease grade. METHODS A 5-point classification system (Grades 1 to 5) was developed based on tumour extension in dorsal and cranio-caudal directions. Cases were then classified as Type A: no arterial circle of Willis or cavernous sinus involvement and Type B: cases in which these blood vessels were involved. RESULTS Medical records and magnetic resonance imaging data of 37 cases with hyperadrenocorticism were reviewed. Thirty-three cases underwent surgery; 4 Grade 5 cases did not have appropriate indications for surgery, and other therapies were used. Complete resection was achieved for 3, 3, 22 and 1 Grade 1A, 2A, 3A and 3B cases, respectively. Resection was incomplete in 1, 1 and 2 Grade 3A, 3B and 4B cases, respectively. Remission was achieved in 29 cases. Recurrence occurred in 4 cases, all of which were classified as Grade 3. CLINICAL SIGNIFICANCE Dogs with Type A, Grade 1 to 3 hyperadrenocorticism had a good prognosis following trans-sphenoidal hypophysectomy. Grade 3B, 4 and 5 cases may not be suitable for this surgery.

Cervical intervertebral disk herniation in chondrodystrophoid and nonchondrodystrophoid small-breed dogs: 187 cases (1993–2013)

OBJECTIVE To identify characteristics of chondrodystrophoid and nonchondrodystrophoid small-breed dogs with cervical intervertebral disk herniation (IVDH). DESIGN Retrospective case series. ANIMALS 187 small-breed (≤ 15 kg [33 lb]) dogs that underwent surgery because of cervical IVDH. PROCEDURES Medical records were reviewed for information on breed, sex, age, weight, location of affected intervertebral disks, duration and severity of neurologic signs, and recovery time. RESULTS 55 of the 187 (29.4%) dogs were Beagles. The most frequently affected intervertebral disk was C2-3 (81/253 [32.0%]), and this was the more frequently affected intervertebral disk in dogs of several chondrodystrophoid breeds, including Beagles (29/66 [43.9%]), Dachshunds (13/37 [35.1%]), Shih Tzus (16/41 [39.0%]), and Pekingese (3/10 [30.0%]). However, caudal disks (C5-6 or C6-7) were more frequently affected in Yorkshire Terriers (13/24 [54.2%]) and Chihuahuas (9/13 [69%]). Shih Tzus and Yorkshire Terriers were significantly older at the time of surgery (mean ± SD age, 9.6 ± 2.3 years and 9.5 ± 2.5 years, respectively) than were Pomeranians (6.2 ± 2.3 years), and Yorkshire Terriers had a significantly higher number of affected disks (2.0 ± 0.9) than did Dachshunds (1.1 ± 0.3). Mean recovery time was significantly longer in Yorkshire Terriers (36.7 ± 13.0 days) than in Beagles (16.5 ± 17.1 days), Shih Tzus (17.8 ± 14.5 days), or Chihuahuas (12.2 ± 7. 2 days). CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that there may be breed-specific differences in the characteristics of cervical IVDH in small-breed dogs.

Evaluation of the dens-to-axis length ratio and dens angle in toy-breed dogs with and without atlantoaxial instability and in healthy Beagles

OBJECTIVE To evaluate and compare morphological characteristics of the dens in atlantoaxial instability (AAI)-predisposed toy-breed dogs (TBDs) with and without AAI and non-AAI-predisposed healthy Beagles. ANIMALS 80 AAI-affected and 40 nonaffected TBDs and 40 Beagles. PROCEDURES Each dog underwent CT examination of the cervical vertebral column. On median 3-D multiplanar reconstruction images, the dens angle (DA) was measured as were the lengths of the dens and the body of the axis; the dens-to-axis length ratio (ratio of the dens length to the axis body length [DALR]) was calculated. Data were compared among dog groups. RESULTS The DALR in nonaffected TBDs and Beagles did not differ significantly. The mean DALR for AAI-affected TBDs was significantly lower than that for nonaffected TBDs. The mean DA of AAI-affected TBDs was significantly greater than that of Beagles and nonaffected TBDs. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that a low DALR might be associated with a high probability of dens abnormalities in TBDs. Additionally, dens length in AAI-affected TBDs appeared to be smaller than that in non-AAI-affected TBDs, given the low DALR in AAI-affected TBDs. Further investigations to determine reference ranges of the DA and DALR and the potential usefulness of those variables as diagnostic markers for AAI in TBDs are warranted.

Evaluation of the survival of bone marrow-derived mononuclear cells and the growth factors produced upon intramedullary transplantation in rat models of acute spinal cord injury

Intramedullary bone marrow-derived mononuclear cell (BM-MNC) transplantation has demonstrated neuroprotective effects in the chronic stage of spinal cord injury (SCI). However, no previous study has evaluated its effects in the acute stage, even though cell death occurs mainly within 1week after injury in all neuronal cells. Moreover, the mechanism underlying these effects remains unclear. We aimed to investigate the survival of intramedullary transplanted allogeneic BM-MNCs and the production of growth factors after transplantation to clarify the therapeutic potential of intramedullary transplanted BM-MNCs and their protective effects in acute SCI. Sprague-Dawley rats were subjected to traumatic SCI and received intramedullary transplantation of EGFP(+)BM-MNCs (n=6), BM-MNCs (n=10), or solvent (n=10) immediately after injury. To evaluate the transplanted BM-MNCs and their therapeutic effects, immunohistochemical evaluations were performed at 3 and 7days post-injury (DPI). BM-MNCs were observed at the injected site at both 3 (683±83 cells/mm(2)) and 7 DPI (395±64 cells/mm(2)). The expression of hepatocyte growth factor was observed in approximately 20% transplanted BM-MNCs. Some BM-MNCs also expressed monocyte chemotactic protein-1 or vascular endothelial growth factor. The demyelinated area and number of cleaved caspase-3-positive cells were significantly smaller in the BM-MNC-transplanted group at 3 DPI. Hindlimb locomotor function was significantly improved in the BM-MNC-transplanted group at 7 DPI. These results suggest that intramedullary transplantation of BM-MNCs is an efficient method for introducing a large number of growth factor-producing cells that can induce neuroprotective effects in the acute stage of SCI.

Biomechanical evaluation of three ventral fixation methods for canine atlantoaxial instability: a cadaveric study

We evaluated comparatively the mechanical strength in three kinds of surgical fixation techniques for canine atlantoaxial joint. Atlantoaxial plate fixation (APF), polymethylmethacrylate (PMMA) fixation (PMF) and transarticular fixation (TAF) were applied to the atlas and axis harvested from healthy beagle dogs, and then, the specimens were tested. The PMF group had significantly higher resistance to flexion than the APF group (P=0.030) and the TAF group (P=0.004). There were no significant differences in resistance to torsion between the APF group and the PMF group, while the APF group had significantly higher resistance to torsion than the TAF group (P=0.037). Considering the possible drawbacks of using PMMA, the APF method is proposed as an alternative to the PMF method.

Clinical Efficacy of Bone Reconstruction Surgery with Frozen Cortical Bone Allografts for Nonunion of Radial and Ulnar Fractures in Toy Breed Dogs

OBJECTIVE  To evaluate the effectiveness of frozen cortical bone allografts (FCBA) in the treatment of severe radial and ulnar atrophic nonunion fractures. ANIMALS  Toy breed dogs with nonunion of radial and ulnar fractures (n = 15). METHODS  Severe atrophic nonunion fractures were treated with FCBA (eight infected and seven non-infected fractures). Radiographs obtained immediately after surgery, and 1, 2, 3, 6 and 12 months later were evaluated and scored for the periosteal reaction at the bone regeneration sites, the healing process in the bone connection areas at both the proximal and distal sites, and the bone remodelling process within the allografts. RESULTS  Improvements in the fracture-healing process and weight-bearing function were observed in all cases. Radiographic scores at the bone connection areas and within the allograft improved significantly over time (p < 0.05). There were not any significant differences in radiographic scores between the infected and non-infected groups. CLINICAL SIGNIFICANCE  Bone reconstruction with FCBA is effective in the treatment of radial and ulnar nonunion fractures associated with large bone defects, regardless of the infection status of the surgical site.

Atlantooccipital overlapping and its effect on outcomes after ventral fixation in dogs with atlantoaxial instability

We compared clinical outcomes after ventral fixation in dogs with atlantoaxial instability (AAI) on the basis of the presence or absence of atlantooccipital overlapping (AOO). Of 41 dogs diagnosed with AAI and treated ventral fixation, 12 exhibited AOO (AOO group), whereas 29 did not (non-AOO group). The AOO group had significantly higher neurological scores before (P=0.024) and 1 month after (P=0.033) surgery compared with the non-AOO group; however, no significant differences were observed between the groups 2 months after surgery. The presence of complicating AOO affected the clinical signs for dogs with AAI, but did not directly affect the outcome of surgical stabilization of AAI.

Epidemiological and morphological characteristics of incomplete ossification of the dorsal neural arch of the atlas in dogs with atlantoaxial instability

OBJECTIVE To retrospectively evaluate the epidemiological and morphological features and outcome of surgical treatment of incomplete ossification of the dorsal neural arch of the atlas (IODA) in dogs with atlantoaxial instability (AAI). ANIMALS 106 AAI-affected dogs that underwent ventral fixation of the atlantoaxial joint. PROCEDURES Medical records and CT images for each dog were reviewed. Dogs were allocated to 1 of 2 groups on the basis of the presence or absence of IODA or of dens abnormalities (DAs) in CT images. RESULTS Of the 106 dogs with AAI, 75 had and 31 did not have IODA; 70 had and 36 did not have DAs. Incomplete ossification was present in the cranialmost, central, or caudalmost portion of the dorsal neural arch of the atlas in 59, 39, and 28 dogs, respectively; 2 or 3 portions were affected in 29 and 11 dogs, respectively. The mean CT value (in Hounsfield units) for the midline of the dorsal neural arch of the atlas in dogs with IODA was significantly lower than that for the same site in the dogs without IODA. The mean age at surgery for dogs with central IODA was significantly higher than that of the non-IODA group. The severity of spinal cord injury before or after atlantoaxial ventral fixation did not differ between the IODA and non-IODA groups. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that concomitant DAs or IODA is common in dogs with AAI. In dogs with incomplete ossification in the central part of the dorsal neural arch of the atlas, surgical treatment of AAI generally occurs at a middle to advanced age.