Patellar groove replacement in patellar luxation with severe femoro-patellar osteoarthritis.

OBJECTIVE: To report a novel method of treating femoro-patellar instability in association with severe femoro-patellar osteoarthritis, by substituting the femoral trochlear with a patellar groove replacement prosthesis. STUDY DESIGN: Retrospective case series. METHODS: Preoperative lameness was scored from 0-4, and radiographic studies including standard positions for patellar luxation were obtained for evidence of malalignment and femoro-patellar osteoarthritis. Cases with or without previous surgeries were included. The size of trochlear implant was determined by transparent templates and confirmed intra-operatively with trials. Radiographic images, together with clinical examinations, were reviewed immediately and at three months postoperatively and at longer term when available. RESULTS: Thirty-five cases of patellar luxation ranging from grades II to IV were included. Eleven of these cases had prior surgical interventions which failed to stabilize the patella. Fourteen dogs required additional surgical procedures in conjunction with patellar groove replacement. Complications occurred in six patients, of which three required revision. Complete resolution of subjectively-assessed lameness was evident in 24/35 cases by the third month and in another seven of 35 patients on the longer term re-evaluations. CLINICAL SIGNIFICANCE: Use of a patellar groove replacement prosthesis has the potential to decrease the lameness associated with severe femoro-patellar arthritis, to improve patellar stability, and to correct the alignment of the extensor mechanism.

The use of cyclosporine-A in dogs with chronic osteoarthritis: a pilot study.

OBJECTIVE: To evaluate the efficacy of cyclosporine-A in dogs with radiographic and physical evidence of chronic stifle osteoarthritis. MATERIALS AND METHODS: Ten hound-type dogs with osteoarthritis induced by surgical transection of a cranial cruciate ligament followed by immediate stabilization of the stifle four years prior to study start were randomized to two groups. Cyclosporine-A was administered orally once daily at 5 mg/kg to one group for one month while the other group served as control. After a two week wash-out period during which the animals were not treated, and the degree of lameness was allowed to return to baseline, the treatments were switched so that the second group received treatment with cyclosporine-A and the first group served as control. Ground reaction forces were measured using a force platform in all animals at day zero and then every two weeks until the end of the study. RESULTS: Cyclosporine-A did not alter the degree of lameness based on assessment of ground reaction forces. CONCLUSIONS: At a dose of 5 mg/kg/day for 28 days, cyclosporine-A was not effective in decreasing lameness of dogs with chronic osteoarthritis induced by surgical transection of the cranial cruciate ligament.

Radiographic, densitometric, and biomechanical effects of recombinant canine somatotropin in an unstable ostectomy gap model of bone healing in dogs.

OBJECTIVE: To determine the effect of recombinant canine somatotropin (STH) on radiographic, densitometric, and biomechanical aspects of bone healing using an unstable ostectomy gap model. STUDY DESIGN: After an ostectomy of the midshaft radius, bone healing was evaluated over an 8-week period in control dogs (n = 4) and dogs receiving recombinant canine STH (n = 4). ANIMALS OR SAMPLE POPULATION: Eight sexually intact female Beagle dogs, 4 to 5 years old. METHODS: Bone healing was evaluated by qualitative and quantitative evaluation of serial radiographs every 2 weeks. Terminal dual-energy x-ray absorptiometry and three-point bending biomechanical testing were also performed. RESULTS: Dogs receiving STH had more advanced radiographic healing of ostectomy sites. Bone area, bone mineral content, and bone density were two to five times greater at the ostectomy sites of treated dogs. Ultimate load at failure and stiffness were three and five times greater in dogs receiving STH. CONCLUSIONS: Using the ostectomy gap model, recombinant canine STH enhanced the radiographic, densitometric, and biomechanical aspects of bone healing in dogs. CLINICAL RELEVANCE: Dogs at risk for delayed healing of fractures may benefit from treatment with recombinant canine STH.

The effects of plate type, angle of ilial osteotomy, and degree of axial rotation on the structural anatomy of the pelvis.

Unilateral triple pelvic osteotomy was performed with three variations in technique on canine cadaver pelves. The following variables were studied: the angle of the ilial osteotomy (perpendicular to the long axis of the ilium and 10 degrees, 20 degrees, and 30 degrees off perpendicular); the degree of axial rotation (20 degrees, 30 degrees, and 45 degrees); and the type of fixation (canine pelvic osteotomy plate [CPOP] or a 2.7-mm dynamic compression plate [DCP]). Structural changes measured were the pelvic inlet and acetabular area, interischiatic tuberosity distance, and degree of acetabular version. Means and standard error of the means were determined for all pelvic measurements and were analyzed by three-way analysis of variance (P < .05). As the axial rotation increased from 20 degrees to 45 degrees an ilial osteotomy angled 10 degrees, 20 degrees, or 30 degrees resulted in a significantly greater decrease in the pelvic inlet area and significantly less deviation of the interischiatic tuberosity distance and degree of acetabular version from normal than an osteotomy directed perpendicular to the long axis of the ilium. Compared with the CPOP, as the axial rotation increased from 20 degrees to 45 degrees, the DCP resulted in a significantly greater decrease in the pelvic inlet area, an increase in the interischiatic tuberosity distance and degree of acetabular version, and less of an increase in the acetabular area. The results of this study suggest that to maximize dorsal acetabular coverage, while minimizing disruption of normal pelvic architecture, a CPOP and an ilial osteotomy angled 10 degrees to 30 degrees are preferred for all degrees of axial rotation.

Biomechanics of the normal and abnormal hip joint.

Static analysis of the canine hip has given some insight to the nature and trend of the force and subsequent stress that is normally applied to the joint. Using the static model, the magnitude and direction of force and stress worsens in the hip with the anatomic and stability changes associated with CHD. More sophisticated dynamic models that take into account unbalanced forces and moments with the resultant motion are needed to better understand the mechanics of the hip joint.

Thoracic, abdominal, and vertebral actinomycosis. Diagnosis and long-term therapy in three dogs.

The clinical, laboratory, radiographic, and histologic features and the response to therapy in three dogs with actinomycosis are reported. One dog (dog 1) had a 12-cm nonresectable mass extending from the ventrolateral chest wall into the left ventricular myocardium. Another dog (dog 2) had a diffuse peritonitis with "sulfur granules" and two large masses. One of these masses was nonresectable involving adjacent abdominal structures. A third dog (dog 3) had a subvertebral mass at T1-3 producing quadraplegia. Two dogs had periosteal reactions involving adjacent sternebrae (dog 1) or ribs and vertebral bodies (dog 3) that are characteristic of Actinomyces spp infections. In dogs 1 and 2 the diagnosis was based on the morphologic and tinctorial properties of free sulfur granules and/or tissue granules. Culture results were variable. Tissue from dog 1 yielded no growth, while polymicrobial infections, which included Actinomyces spp, were identified in dogs 2 and 3. Actinomyces odontolyticus was isolated from dog 3. Although the actinomycotic granulomas were either not excised or only partially excised from dogs 1 and 2, both animals were cured by the oral administration of high doses of penicillin G for 19 and 6 months, respectively. Dog 3 responded dramatically to the same antibiotic therapy given for 5 months. However, within 4 months of discontinuing treatment an abscess and draining fistulous tracts developed in the left axillary region. Two surgical fistulectomies and additional penicillin therapy were required to cure this animal. These cases and the current veterinary and human literature on actinomycosis are used to propose a rational approach to the treatment of actinomycosis in the dog.

Growth deformities.

This article discusses principles of corrective osteotomy and describes operative plans for specific growth deformities such as premature closure of the distal ulna, asynchronous growth of the radius and ulna in achondroplastic breeds, retarded growth of the distal radius, retarded growth of the proximal radius, and synostosis of the radius and ulna.

Effects of exposure to ambient air on articular cartilage of rabbits.

Effects of exposure to ambient air (20 to 22 C) on articular cartilage from rabbits were evaluated. Bilateral arthrotomies were performed on the stifles of 18 New Zealand White rabbits. The cranial surface of the left distal femur, including the articular cartilage of the trochlea, was exposed to air for 2 hours. The right stifle was opened and closed immediately. Six rabbits were killed at the end of the surgical operation (group 1), 6 after 2 weeks (group 2), and 6 after 4 weeks (group 3), and femurs were harvested. A distinct color change was seen in the exposed cartilage in group 1; however, minimal change was detected in group 2, and no change was seen in group 3. Proteoglycan content did not differ between the exposed and control cartilage in any group. The number of viable cells and empty lacunae in articular cartilage did not differ between the exposed and control femurs. Total cell counts and degenerative cell counts were similar, comparing the left and right trochlea in groups 1 and 3. A significant increase in cellularity was noticed in the radial zone of the exposed cartilage in group 2 (P less than 0.01). In the same group, a significantly increased number of degenerative cells were seen in the tangential zone of the exposed cartilage (P less than 0.05). Changes in cellularity were consistent with cartilage damage. Seemingly, exposing articular cartilage to air for 2 hours causes reversible cartilage damage.

Effects of tenotomy of the tensor tympani muscle on the acoustic reflex in dogs.

The acoustic reflex (AR) was recorded from 12 healthy mixed-breed dogs. Latency and amplitude were measured from ipsilateral and contralateral AR at stimulus frequencies of 1 and 2 kHz and intensities of 70 to 110 dB sound pressure level for ipsilateral AR and 70 to 120 dB hearing level for contralateral AR. Mean latencies for ipsilateral and contralateral AR were between 33.46 and 206.10 ms and between 45.26 and 180.89 ms, respectively, and amplitudes were between 0.14 and 1.79 cm3 and between 0.31 and 1.86 cm3 of air, respectively. Stimulus frequencies and intensities had significant effects (P less than 0.05) on ipsilateral and contralateral AR latencies and amplitudes. Ipsilateral and contralateral AR decays were determined by measuring compliance change during a 10-s pure-tone stimulation at frequencies of 1 and 2 kHz at an intensity of 10 dB above AR threshold. Reflex decays for 1 kHz and 2 kHz frequencies averaged 5.74% and 9.71%, respectively, for ipsilateral AR and 5.08% and 5.40%, respectively, for contralateral AR. Bilateral tympanograms and brain stem auditory-evoked responses were performed on each dog. Mean normal static compliance of the middle ear, as determined by tympanometry, was 0.15 cm3. Unilateral tenotomy of the tensor tympani muscle was done on 6 of the 12 dogs, and each of the preceding procedures were repeated within 1 week after surgical operation. Transection of the tensor tympani tendon did not alter (P greater than 0.05) the latencies or amplitudes of 1 kHz- or 2 kHz-evoked contralateral AR, the latency or amplitude of 1 kHz-evoked ipsilateral AR, or the amplitude of 2 kHz-evoked ipsilateral AR. However, the latency of 2 kHz-evoked ipsilateral AR was significantly (P less than 0.05) increased. Reflex decay increased significantly (P less than or equal to 0.001) for the contralateral reflex elicited by the 2 kHz stimulus. Neither compliance of the middle ear system nor amplitude and latency of the brain stem auditory-evoked response were affected (P greater than 0.05) by tenotomy. Since tenotomy eliminates participation of the tensor tympani in the AR, these data indicate that contraction of this muscle is not primarily responsible for the compliance changes recorded during an acoustic reflex in dogs.

Preliminary study on the use of ultrasonic transmission imaging to evaluate the hip joint in the immature dog.

Real-time ultrasonic transmission imaging presents an orthographic image of anatomy similar to that obtained with X-ray fluoroscopy. Transmission imaging allows visualization of the dynamic interaction of muscle, cartilage, bone, tendon and joints during selective palpation and movement. The hip joints of deceased dogs, 7-8 weeks of age, were sonographically evaluated at various levels of dissection and correlated with anatomic features. Wherever possible correlation was made qualitatively with radiographs of the pelvis and coxofemoral joints. Although some features of the hip could be imaged, ultrasonic transmission imaging will require additional research and development before it is proven to be a useful diagnostic adjunct in clinical veterinary medicine.