Distraction-fusion for caudal cervical spondylomyelopathy using an intervertebral cage and locking plates in 14 dogs.

OBJECTIVE: To evaluate clinical and radiographic outcome in dogs with caudal cervical spondylomyelopathy (CCSM) treated with an intervertebral fusion cage and locking plates. STUDY DESIGN: Prospective clinical study. ANIMALS: Large breed dogs (n=14) with CCSM. METHODS: Dogs had single level cervical spine distraction/fusion performed using an intervertebral cage with a hollow center filled with cancellous autograft and 2 ventrally applied locking plates. Outcome was measured using neurologic scores and radiographic interpretation 6 weeks, 6 months, and 12 months postoperatively. RESULTS: The surgical procedure was well tolerated in all dogs. Final outcome at 12 months was available in 9 dogs. Five dogs were judged excellent, 1 dog was good, 2 dogs were satisfactory, and 2 dogs were poor because of adjacent segment disease. Four dogs died for reasons unrelated to the procedure. Radiographically, implants remained stable over the entire follow-up period. The disc space continued to fill with an immature pattern of new bone, which showed progressive increase in opacity and quantity. Subsidence of the cage (median 2 m) was detected in 9 dogs at 6 weeks and remained unchanged in those that could be followed further. CONCLUSION: Distraction-fusion of single level CCSM in dogs with a combination of intervertebral cage and ventral locking plates is clinically effective and results in successful bony fusion.

Comparison of healing of the osteotomy gap after tibial tuberosity advancement with and without use of an autogenous cancellous bone graft.

OBJECTIVE: To evaluate and compare healing, with and without the use of bone graft, of the gap created during tibial tuberosity advancement (TTA). STUDY DESIGN: Prospective study and case series. ANIMALS: Dogs treated with TTA (n=67). METHODS: Prospective study: Mediolateral radiographic projections (6 weeks and 4 months) after TTA without use of bone graft (group I, n=14) were compared with radiographs of consecutive TTA in which the gap was filled with autologous cancellous bone graft (group II, n=14). Two scoring techniques (A, B) were used. Score A was used to grade the overall osteotomy healing (0=no healing, 4=healed osteotomy). Score B evaluated, independently of each other, healing in 3 sites: proximal to the cage (B1), between cage and plate (B2), and distal to the plate (B3). CASE SERIES: nongrafted TTA (4-25 weeks, n=39) were evaluated for healing (Score A). Data was analyzed using t-tests and ANOVA. Significance was set at P≤.05. RESULTS: Prospective study: Score A, B2, and B3 showed no difference in healing between groups at 6.8 weeks and 4.2 months. Score B1 revealed, in both rechecks, a significantly higher density in group II. case series: Radiographs at 11.59±5.99 weeks scored 3.3 (2-4). No healing related complications were observed. CONCLUSION: The osteotomy gap created during TTA healed within expected time regardless of bone graft use.

Correlation of radiographic changes after tibial tuberosity advancement in dogs with cranial cruciate-deficient stifles with functional outcome.

OBJECTIVE: To (1) evaluate radiographic changes associated with osteoarthrosis (OA) before and after tibial tuberosity advancement (TTA) and (2) determine if these changes are indicative of limb function as determined by kinetic gait analysis. STUDY DESIGN: Prospective clinical study. ANIMALS: Dogs (n=35) with cranial cruciate ligament (CCL) deficient stifles (38). METHODS: Variables recorded were: complete or partial CCL rupture, meniscal lesions, arthroscopically graded cartilage lesions, complications, and revision surgeries. Radiographic evaluation and kinetic gait analysis (vertical ground reaction forces [GRFs]) were conducted pre- and 4-16 months postoperatively (mean, 5.9 months). Radiographs were evaluated without knowledge of operative findings and functional outcome. A score (0-3) based on new bone production at 11 specific sites was used to grade OA. Soft tissue changes were classified separately as normal or excessive. Preoperative scores were correlated with clinical variables. Postoperative scores and progression of OA scores were correlated with clinical variables and GRFs. RESULTS: OA remained unchanged in 17 joints and progressed in 21 (55%). Dogs with meniscal lesions had higher OA scores preoperatively, but not at follow-up. Dogs with severe cartilage lesions at surgery had more progression of OA. GRFs improved after surgery and were not correlated with any of the radiographic OA scores. CONCLUSION: Progression of OA was greater in the presence of severe cartilage lesions at surgery. OA scores were not correlated with GRFs. CLINICAL RELEVANCE: Progression of OA is generally expected to occur after TTA despite improvement of limb function.

Asymmetrical, transitional, lumbosacral vertebral segments in six dogs: a characteristic spinal syndrome.

Clinical findings in six dogs with asymmetrical, transitional, lumbosacral vertebral segments are reported. All dogs exhibited low back pain and varying degrees of asymmetrical cauda equina dysfunction. Results of myelography, epidurography, and magnetic resonance imaging (MRI) indicated a unilateral disk protrusion in all dogs. In the dogs with MRIs, focal degenerative alterations in the vertebral end plates and adjacent body of the vertebra were detected. All dogs were treated with a dorsal laminectomy or hemilaminectomy. Results following surgery were good or excellent in all six dogs.

Lumbosacral transitional vertebrae in dogs: classification, prevalence, and association with sacroiliac morphology.

The prevalence of lumbosacral transitional vertebrae (LTV) was determined by reviewing the pelvic radiographs of 4000 medium- and large-breed dogs of 144 breeds routinely screened for canine hip dysplasia. An LTV was seen in 138 (3.5%) dogs. The prevalence was higher in German Shepherd dogs and Greater Swiss Mountain dogs than in the other breeds, suggesting a genetic predisposition. There was no gender predisposition. The transverse processes of the LTV were divided into three types based on their morphological characteristics: lumbar type or type 1; intermediate type or type 2; and sacral type or type 3. In a symmetric LTV, both transverse processes are of the same type, while in an asymmetric LTV they are not. The frequency of occurrence of symmetric and asymmetric LTV was similar. In symmetric LTV, intermediate-type transverse processes predominated. Most of the asymmetric LTV had an intermediate-type transverse process combined with a lumbar or sacral type, respectively. Highly asymmetric LTV were often angled relative to the adjacent vertebrae. We hypothesize that an LTV is not the result of transformation of a lumbar into a sacral vertebra or vice versa, but rather is an autonomous intermediate type of vertebra. It occurs when the point of contact of the pelvis with the vertebral column is slightly cranial or caudal to its normal position. The resulting formative stimulus on the vertebral ossification centers, sagittally still separated, causes the various morphologies seen in LTV including the asymmetric variations.

A lumbosacral transitional vertebra in the dog predisposes to cauda equina syndrome.

The association between the occurrence of a lumbosacral transitional vertebra (LTV) and the cauda equina syndrome (CES) in dogs was investigated. In 4000 control dogs without signs of CES, 3.5% had an LTV, while in 92 dogs with CES, 16.3% had an LTV. The lesion causing CES always occurred between the last true lumbar vertebra and the LTV. Dogs with an LTV were eight times more likely to develop CES than dogs without an LTV. German Shepherd dogs were eight times more likely to develop CES compared with other breeds. Male dogs were twice as likely to develop CES than females. Dogs with an LTV develop CES 1-2 years earlier than dogs without an LTV.

Sensitivity of radiographic evaluation of radio-ulnar incongruence in the dog in vitro.

OBJECTIVE: To determine the sensitivity and specificity of radiographic evaluation of radio-ulnar incongruence in canine elbow joints in vitro. STUDY DESIGN: Radiographic evaluation of induced radio-ulnar incongruence in canine cadaveric forelimbs by radiologists blinded to study design. SAMPLE POPULATION: Six cadaveric canine left forelimbs. METHODS: Extended lateral, 90 degrees flexed lateral, and cranio-caudal projections were taken of the elbow joint of six cadaveric canine forelimbs. A four-pin, type I external skeletal fixator (ESF) with a linear motor side bar was attached to the medial aspect of the radius, and a 2-cm segment of bone was removed from the mid-diaphysis. A 3.5-mm cortical bone screw placed from the medial to lateral styloid processes prevented relative movement between the distal radius and ulna during radial shortening. The ESF was used to progressively shorten the radius in increments of 0.5 mm to a total of 4 mm. The three radiographic projections were repeated after each incremental change of length. After the study, each elbow joint was disarticulated to confirm the presence of a step defect. The original radiographs and three copies were randomized and then evaluated by four radiologists blinded to the study design. Radiologists were asked to evaluate whether the joint was normal or abnormal and if there was evidence of radio-ulnar incongruence. The ability of each radiologist to correctly identify congruent elbows (specificity) and incongruent elbows (sensitivity) was calculated. RESULTS: The median specificity was 86% using the lateral projection and 82% using the cranio-caudal projection. The median sensitivities using the lateral and cranio-caudal radiographic projections were 78% and 79%, respectively. The degree of radial shortening required for individual radiologists to achieve a sensitivity of 90% ranged from 1.5 mm to greater than 4 mm. CLINICAL RELEVANCE: Standard radiographic evaluation for radio-ulnar incongruence in the dog may be associated with relatively poor sensitivity and specificity. Invasive surgical procedures and screening programs that rely on radiographic diagnosis of radio-ulnar incongruence should be discouraged until a more reliable method of diagnosis of this type of elbow joint incongruence is available.