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  • Author or Editor: Masakazu Shimada x
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Abstract

OBJECTIVE

To verify the validity of finite element analysis (FEA) predictions obtained from a canine lumbar segment model in comparison with experimental biomechanical testing results from the same subjects.

ANIMALS

6 healthy beagle dogs were euthanized for other purposes.

METHODS

The L1–2 and L5–6 segments were harvested from euthanized animals and subjected to rotation tests and compression tests, respectively, using both ex vivo mechanical testing and FEA. For each method, we recorded the maximum torque value and angle of vertebral body rotation at rupture observed in rotation tests, as well as the maximum stress value and displacement of the vertebral body endplate at rupture measured from compression tests. We then calculated Pearson’s correlation coefficient to determine correlations between the angle of gyration and displacement at rupture determined by mechanical testing and FEA. The study started on March 26, 2021, and ended on March 18, 2023.

RESULTS

For the rotation test, correlation coefficients for the maximum torque and rotation angle of the vertebral body at rupture were r = 0.92 and 0.96, respectively. For the compression test, correlation coefficients for the maximum stress and displacement of the vertebral body endplate at rupture were r = 0.73 and 0.94, respectively. All results showed strong correlations between the FEA predictions and ex vivo mechanical test results.

CLINICAL RELEVANCE

These findings suggest that FEA predictions are sufficiently reliable for ex vivo mechanical test results for biomechanical studies of canine lumbar segment models.

Open access
in American Journal of Veterinary Research

Abstract

OBJECTIVE

To investigate the effect of an excessive tibial plateau angle (TPA) and change in compressive load on tensile forces experienced by the cranial cruciate, medial collateral, and lateral collateral ligaments (CCL, MCL, and LCL, respectively) of canine stifle joints.

SAMPLE

16 cadaveric stifle joints from 16 orthopedically normal Beagles.

PROCEDURES

Stifle joints were categorized into unchanged (mean TPA, 30.4°) and excessive (mean TPA before and after modification, 31.2° and 41.1°, respectively) TPA groups. The excessive TPA group underwent a TPA-increasing procedure (curvilinear osteotomy of the proximal aspect of the tibia) to achieve the desired TPA. A robotic system was used to apply a 30- and 60-N compressive load to specimens. The craniomedial band of the CCL, caudolateral band of the CCL, MCL, and LCL were sequentially transected; load application was repeated after each transection. Orthogonal force components were measured in situ. Forces on ligaments were calculated after repeated output force measurements as the contribution of each component was eliminated.

RESULTS

Increasing the compressive load increased tensile forces on the craniomedial and caudolateral bands of the CCL, but not on the MCL or LCL, in specimens of both groups. At the 60-N load, tensile force on the craniomedial band, but not other ligaments, was greater for the excessive TPA group than for the unchanged TPA group.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that stress on the CCL may increase when the compressive load increases. The TPA-increasing procedure resulted in increased tensile force on the CCL at a 60-N compressive load without affecting forces on the MCL or LCL.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE

To determine the signalment and musculoskeletal morphology of small-breed dogs affected by medial patellar luxation (MPL) grade IV based on the age of the CT scan.

ANIMALS

40 small-breed dogs (54 limbs) with MPL grade IV.

PROCEDURES

Dogs that had undergone corrective surgery for MPL grade IV and had performed CT of the hind limb before surgery were included. Signalment (age, body weight, sex, laterality, and breed) and concomitant cranial cruciate ligament rupture (CrCLR) were recorded. Femoral inclination angle, anatomical lateral distal femoral angle (aLDFA), femoral torsion angle, quadriceps muscle length to femoral length ratio (QML/FL), and patellar ligament length to patellar length were obtained by CT images. The dogs were categorized into 2 groups based on their age at the time of the CT scan, the skeletally immature group and the skeletally matured group. Signalment and group were included in the multiple regression analysis to determine the factors associated with each measurement parameter. A logistic regression analysis was conducted to determine the risk of CrCL concomitant with age.

RESULTS

The multiple regression model demonstrated that the group was associated with the value of aLDFA and QML/FL. aLDFA was higher, and QML/FL was lower in group SI than in group SM. CrCLR was present in 5/54 limbs (9.2%), with a mean age of 70.8 months and it was associated with increasing age.

CLINICAL RELEVANCE

In Singleton’s classification, dogs classified as grade IV can be categorized into 2 groups based on musculoskeletal morphology and pathophysiology: the skeletally immature and skeletally matured types.

Open access
in American Journal of Veterinary Research

Abstract

OBJECTIVE

To retrospectively review the efficacy of combined surgery comprising dorsal laminectomy and dorsal fixation using screws and polymethylmethacrylate as treatment for dogs with degenerative lumbosacral stenosis (DLSS).

ANIMALS

21 client owned dogs diagnosed with DLSS and treated surgically.

PROCEDURES

Based on clinical records, signalments, clinical signs, findings from orthopedic and neurological examinations, imaging findings, and postoperative complications were evaluated at the following time points: preoperatively, postoperatively, and 3, 6, 12, 24, and 36 months after surgery.

RESULTS

In all 21 cases, clinical signs were alleviated, proprioceptive deficits were improved from 3 months after surgery, and no recurrence of clinical signs was observed during the observation period. Minor complications were observed in 6 cases (28.6%), including implant failure in 2 (9.5%), delayed healing of surgical wounds in 2 (9.5%), seroma in 1 (4.8%), and swelling of the affected area in 1 (4.8%). There was no case with major complications.

CLINICAL RELEVANCE

Combined surgery comprising dorsal laminectomy and dorsal fixation using screws and polymethylmethacrylate is a useful treatment that can improve long-term clinical signs in dogs with DLSS.

Full access
in Journal of the American Veterinary Medical Association

Abstract

OBJECTIVE

To compare the prognosis of small dogs with cervical intervertebral disc herniation (C-IVDH) when treated with ventral slot decompression (VSD) alone or with concomitant vertebral fixation (VF).

ANIMALS

Small dogs (n = 303) weighing < 15 kg diagnosed with C-IVDH and treated with VSD.

PROCEDURES

We recorded signalment, cervical myelopathy grade, surgical site, use of VF, degree of adjacent disc degeneration, recovery, recurrence, recurrence site, and postoperative course, including the time elapsed from recovery to recurrence. We examined factors associated with recovery and recurrence during the 30-month postoperative period using multivariate logistic regression analysis.

RESULTS

VF did not affect recovery (P = .79). However, nonchondrodystrophic breeds had poorer recovery (OR, 5.89; P = .023) than chondrodystrophic breeds, and a higher preoperative cervical myelopathy grade (grade 3 or 4) was associated with poorer recovery (OR, 7.09 or 3.46, respectively; P = .019 or .042, respectively), compared with grade 1. VF did not affect recurrence (P = .79); however, increasing age was associated with recurrence (OR, 1.79; P = .001).

CLINICAL RELEVANCE

In small dogs weighing < 15 kg, there was no difference in postoperative recovery and recurrence rates after VSD with or without concomitant VF. Therefore, in small dogs with C-IVDH, even if the slot volume is increased to remove sufficient disc material during VSD, a good prognosis can be achieved with or without VF.

Open access
in Journal of the American Veterinary Medical Association