Search

Objective— To compare shear stability of simulated humeral lateral condylar fractures reduced with either a self-compressing pin or cortical bone screw. Study Design— In vitro biomechanical tests. Sample Population— Bilateral cadaveric canine humeri (n=18) without evidence of elbow disease. Methods— Lateral condylar fracture was simulated by standardized osteotomy. Bone fragments were stabilized with a self-compressing pin or a cortical bone screw (2.7 or 3.5 mm) inserted in lag fashion. Specimens were mounted in a materials testing system and the condylar fragment displaced in a proximal direction until failure. Mechanical testing variables derived from load–deformation curves were compared between stabilization methods using a Student's paired t-test. Results— There were no statistically significant differences for mechanical testing variables between pin and screw stabilized specimens at expected walk and trot loads. Three yield points subjectively coincided with yield of the interfragmentary interface (Y1), bone at the implant interface (Y2), and implant deformation (Y3). Displacements at Y1 were 48–156% greater for pin than screw stabilized specimens. Y2 and Y3 loads were higher for screw than pin stabilized specimens, but likely supraphysiologic for dogs convalescing after surgical repair. Conclusions— A self-compressing pin or a cortical bone screw inserted in lag fashion both provided adequate strength in applied shear to sustain expected physiologic loads through the repaired canine elbow during postoperative convalescence. Clinical Relevance— Because self-compressing pins were easy to implant and mechanical properties were not significantly different than cortical screws at expected physiologic loads, pins should be considered for the repair of traumatic humeral condylar fractures.

SummaryThe objective of this study was to determine whether the non-steroidal anti-inflammatory drug (NSAID) carprofen causes adverse histological changes to cartilage after prolonged administration for treatment of naturally acquired osteoarthritis.Dogs diagnosed with cranial cruciate ligament rupture and secondary osteoarthritis of their stifle joints were divided into two groups: those who had received a standard dose of carprofen for a minimum of four weeks and those who had not received a NSAID for a minimum of one month. Cartilage from the intercondylar notch was obtained when the patients underwent surgical procedures to stabilize the stifle joint. The samples were processed and evaluated for histological differences using haematoxylin and eosin and safranin-O-fast green-iron haematoxylin stains and were graded according to a Mankin scale (graded 0-14) for osteoarthritis.The histopathological findings were variable and included loss of matrix staining, irregularities to the cartilage surface, matrix fragmentation, chondrocyte clustering, matrix degeneration and vascular and synovial invasion (pannus) and were not specific to either group. There was not any significant difference between study groups (p = 0.2721) according to the Wilcoxan rank sum test.

Objective—To determine whether histopathologic changes are detectable in grossly normal medial menisci from dogs with rupture of the cranial cruciate ligament (CCL).Design—Case series.Sample Population—40 medial menisci from dogs with rupture of the CCL and 20 medial menisci from control dogs without stifle joint disease.Procedure—Data evaluated included age, duration of clinical signs, and whether rupture of the CCL was complete or incomplete. Three groups (n = 20/group) were also compared on the basis of 5 histologic criteria; group-1 menisci appeared grossly normal and were obtained from dogs with naturally occurring rupture of the CCL, group-2 menisci were grossly abnormal and were also obtained from dogs with naturally occurring CCL ruptures, and group-3 menisci were collected at postmortem from dogs without stifle joint disease that were of similar age and weight as dogs in groups 1 and 2.Results—Group-2 menisci were significantly different from group-1 and -3 menisci in all histologic criteria. Group-1 menisci were significantly different from control menisci in only 1 of the 5 histologic criteria (cartilage differentiation). Dogs that were ≥ 3 years old had significantly more surface cellularity than did dogs that were < 3 years old. A significant difference was not detected between groups 1 and 2 with regard to completeness of rupture.Conclusions and Clinical Relevance—Histologic changes in meniscal cartilage correlate with gross appearance of the cartilage at time of surgery for rupture of the CCL. On the basis of minimal histologic changes, routine removal of grossly normal menisci does not appear to be warranted. (J Am Vet Med Assoc2001;218:1281–1284)

SummaryA method of closed implantation of a toggle pin bone anchor and prosthetic ligament was developed for the treatment of traumatic canine coxofemoral luxation. Radiographic and anatomical evaluation of the canine femur and acetabulum were performed in order to develop an imaging and instrumentation technique that would allow closed placement of a toggle pin bone anchor under fluoroscopic guidance, while at the same time minimizing, or eliminating, damage to the articular cartilage. The surgical technique was then performed in 14 canine cadaver coxofemoral joints, followed by gross evaluation of implant placement, and potential cartilage or soft tissue damage. The cervical canal radiographic view of the proximal femur allowed placement of the drill hole through the fovea capitis of the femoral head without damaging the articular cartilage. The acetabular fossa was readily distinguishable from the acetabular articular cartilage on both of the lateral and ventrodorsal radiographic views of the pelvis. The toggle pin apparatus was inserted without damage to the articular cartilage in nine out of the fourteen hips and the bone tunnels were situated within the cancellous bone of the femoral neck in each of the nine specimens evaluated. Complications encountered during the procedure included bending and/or breakage of the guide wire in three hips and damage to the articular cartilage in two hips. The success of technique modifications designed to diminish the incidence of these complications awaits investigation in a clinical trial. Closed toggle pinning for canine traumatic coxofemoral luxation has the potential advantage of achieving rapid stabilization of the coxofemoral joint without damage to the articular cartilage and the need for an open approach to the joint. The clinical application of the technique is reported in one patient.The equipment and methodology for closed implantation of a toggle pin bone anchor and prosthetic ligament was developed for the treatment of traumatic coxofemoral luxation. A cadaver study was performed to assess the viability of the technique. Clinical application in one case is described.

Urethral pressure and electromyographic profiles were recorded in 18 adult male cats about 61 months after perineal urethrostomy was done. The loss of striated sphincter function postoperatively was reversible in some cats. The increased frequency of bacterial urinary tract infection seen in cats postoperatively after perineal urethrostomy cannot be explained by compromised urethral sphincter function alone.

SummaryEight conditioned research dogs, whose body weight was between 25 and 30 kg, had unilateral implantation of a Leeds-Keio (LK) synthetic implant (Dacron polyester) immediately after severance and removal of the cranial cruciate ligament (CCL). A rectangular- shaped autograft, composed of fascia lata, was placed within the LK implant in four of the eight dogs; the other four dogs received the LK implant only. Modified Robert Jones bandages were placed on the limbs that had been operated upon; the bandages were left in place for 48 hours. After that time the limbs were not splinted. The dogs were confined to 1.5 m X 3 m kennels, with twice daily leash walks for the duration of the study. Although the joints that received the LK implants were stable immediately after the operation, they all developed progressive effusion, crepitation and instability accompanied by clinically apparent lameness. All of the dogs were euthanatized three months after the operations. Gross examination of the eight joints that had been operated upon confirmed the presence of degenerative joint disease. Three of the eight dogs had “bucket handle” type tears of their medial meniscus in the joints with the LK implant, and the medial menisci in the other five stifle joints that received LK implants had a fibrillated surface texture. Five of the eight LK implants had either ruptured completely or were stretched and frayed to the point where mechanical testing was not justified. Mean breaking strength of the 3 intact LK implants was 6.6% of the contralateral, control CCL. Ingrowth of fibrous tissue into the LK implants was minimal. The synovium from all joints with LK implants had moderate to severely increased cellularity within the synovial villi and supporting stroma consisting predominantly of lymphocytes, plasma cells and macrophages. Multinucleated giant cells formed aggregates around irregular shaped strands of particulate material which was translucent and refractive. Under polarized light, these particles were bright yellow to green consistent with Dacron particles. It was concluded that the LK implant, as implanted in this study, was not a satisfactory replacement for the CCL in dogs.The Leeds-Keio synthetic replacement for the canine cranial cruciate ligament was implanted in eight dogs. All eight dogs developed progressive instability and secondary degenerative joint disease over a period of three months after the operation. It was concluded that the Leeds-Keio ligament, as implanted in this study, is not satisfactory for use in dogs.

SummaryFixation methods for osteochondral shell grafts were studied using replace-ment of a femoral trochlear autograft in rabbits as the model. Twenty skeletally mature rabbits were divided into four groups with five rabbits in each. The articular cartilage of the femoral trochlea, including 2.0 mm of subchondral bone, was removed using a sagittal bone saw. The grafts were immediately reattached using either small Kirschner pins (K-pins), polydioxanone pins (PDP), polydioxanone suture (PDS), or polymethylmethacrylate (PMMA) cement. Six months postoperatively the rabbits were killed and the graft sites compared to the contralateral control using radiography, gross examination, Safranin-O and H & E staining, and sulphate-35 radioactive uptake. Mild degenerative joint changes were evident radio-graphically in all of the operated joints. Articular surface defects at the graft sites were common and included small craters and erosions; a few had larger areas devoid of cartilage. Defects associated with the pin entrance sites were common in the K-pin and PD P groups. The PDS group had the least number of animals with articular surface defects. Safranin-O staining was complete in the PDS group, partial or complete in the K-pin and PD P groups, and partial in all of the joints in the PMM A group. H & E preparations of the cartilage sections were graded from 1 (normal cartilage) to 5 (multiple fissures, severe degradation). The PDS group had a mean (SD) score of 1.8 (0.8), the PD P group 2.4 (1.1), the K-pin group 2.5 (1.3), and the PMM A group 4.6 (0.6). The scores for the PMM A group were significantly greater then the scores for the other groups (p 0.05). Graft fixation using PDS, PDP, or K-pins was technically easy to perform and the results were generally satisfactory. Fixation using PMM A was technically demanding and histological evidence of moderate to severe cartilage degradation was present in all treated joints.Femoral trochlear autografts in rabbits were used to study fixation methods for osteochondral graft fragments. Six months after the operations the graft sites were evaluated using radiographs, gross examination, Safranin-O and H & E staining, and sulphate-35 radioactive uptake. Grafts stabilized using polydioxanone suture had the least number of articular surface defects and the most complete Safranin-O staining.

The most common indications for the use of ESF in femoral fractures are closed transverse, short oblique, and minimally comminuted fractures in the central one third of the bone. External skeletal fixation is usually used in combination with IM pins and wiring techniques. During the process of open reduction and internal fixation, the surgeon should strive for accurate anatomic alignment and stability at the fracture site. The fixator is applied after the internal fixation is in place and the surgical wound is closed. The number of fixation pins placed in each fracture fragment depends on the type of fracture and the stability gained by internal fixation. Partially threaded fixation pins are recommended. They are inserted through skin stab incisions with low-speed power equipment. Recent modifications of the Type Ia fixator may increase fixator rigidity. Important postoperative concerns include exercise restriction, pin tract care, and protection of the fixator from the environment. Complications associated with ESF can be minimized by realizing its indications and limitations.

In dogs surgically treated for biceps tenosynovitis, the most common histopathological findings were fibrosis and collagen degeneration (n=13), synovial villous or vascular hyperplasia (n=10), lymphocytic-plasmacytic infiltrates (n=10), cartilaginous metaplasia (n=8), and ischemic necrosis (n=5). Degree of histopathological changes was associated with degree (p equals 0.000), but not duration (p equals 0.543), of lameness. Furthermore, there was no association between histopathological changes and age or radiographic and arthrographic findings. Cartilage metaplasia was the only histopathological finding in both affected tendons (8/18) and normal control dogs (13/13). Age and size of the control dogs were not determined; however, since all these dogs were clinically normal, fibrocartilaginous metaplasia can be present as an incidental finding in the biceps tendon of origin in dogs.

To determine the effect of surgical technique and use of a rigid centralizing device on stem positioning and geometric reconstruction in the sagittal plane during total hip replacement in dogs.Bilateral femurs from 8 adult mixed-breed canine cadavers.Femurs were prepared for femoral stem implantation, using 4 variations in technique. Proximal femoral reconstruction and femoral stem positioning were evaluated on radiographs.Implants evaluated in this study accurately reconstructed displacement of the femoral head of the intact canine femur in the sagittal plane. Centralization of the distal aspect of the stem was optimized by use of an undersized femoral stem. Ostectomy at the level of the lesser trochanter resulted in the smallest diaphysis-to-implant angle. Anteversion and retroversion of implants significantly decreased the distance between the distal tip of the implant and the adjacent cortex, compared with normoversion. The centralizing device significantly increased the minimum distance between the distal tip of the implant and adjacent cortex but did not improve the odds of actually centralizing the tip of the implant.Malpositioning of implants in the sagittal plane may be minimized through ostectomy at the lesser trochanter and use of an undersized implant positioned in normoversion. Use of a polymethylmethacrylate centralizing device will help eliminate contact between the implant tip and adjacent cortex. Implantation of an undersized femoral component, avoidance of substantial anteversion or retroversion, and use of a rigid centralizing device are recommended when using the prosthesis described-for total hip replacement of dogs.

To test whether femoral ostectomy level, subtrochanteric bone mass removal, and stemsize selection significantly affect stem positioning in canine total hip replacement, and to determine ability of the femoral stem component to restore geometry of the normal femoral head and neck.Femurs from 8 adult mixed-breed canine cadavers.Femurs were systematically prepared, using 8 combinations of 3 surgical preparation techniques that included level of ostectomy (cervical isthmus vs lesser trochanter), subtrochanteric bone block removal, and femoral stem size (recommended, undersized). Computer-aided analysis of specimen photographs was used to evaluate femoral head offset and position and variability of femoral stem positioning for each of the preparation combinations.Original femoral head offset and position were reconstructed to within a mean of 0.052 and 0.031 cm, respectively, using an undersized femoral stem after ostectomy at the level of the lesser trochanter. Implantation of an undersized femoral stem after subtrochanteric bone block removal improved ability to centralize the distal tip of the implant and reduce the angle between the femoral diaphyseal and implant axes. Ostectomy at the level of the cervical isthmus tended to force femoral implants into a varus position, and ostectomy at the level of the lesser trochanter tended to force implants into a valgus position.Geometry of normal canine femurs was most closely reconstructed by implantation of an undersized femoral component after ostectomy at the level of the lesser trochanter. Implantation of an undersized femoral component after subtrochanteric bone block removal resulted in the best alignment and centralization of the stem.

To document gross and microscopic anatomic features of the collateral ligaments of the canine cubital joint and to determine their structural and material properties.37 canine cadavers.After measurement of ligament dimensions, the bone-collateral ligament-bone specimens were loaded in tension until failure, using a materials testing machine. Data from the load-displacement curves were used to determine the structural and material properties of the ligaments. Gross anatomic features were studied during dissection of the specimens from the medial collateral ligament (MCL) and lateral collateral ligament (LCL), which then were saved for microscopic examination.Failure load and stiffness values for the LCL were significantly (P0.05) greater than those for the MCL. The LCL had obvious cranial and caudal components that attached to the radius and ulna, respectively. The MCL also had cranial and caudal components; however, the cranial component was indistinct, appearing only as a slight thickening of the joint capsule. The caudal component was more prominent; as it extended distad, it had minor attachments to the interosseous and annular ligaments and attached principally on the caudolateral surface of the proximal portion of the radius. The caudal component did not have substantial attachment to the ulna in any of the specimens studied. Both ligaments were composed of closely packed, parallel fascicles of dense collagen, with scant amounts of fibrocartilage and no detectable elastin.Gross anatomic features of the collateral ligaments of the canine cubital joint indicate that they provide principal structural support to the joint; microscopic anatomic features are typical of other ligaments. The LCL is stronger and stiffer than the MCL; however, their material properties are similar.Knowledge of the sites of attachment of collateral ligament components is essential for surgeons undertaking repair or reconstruction of these structures.

To determine whether the nonsteroidal anti-inflammatory drug carprofen directly influences canine chondrocyte metabolism.Cartilage from the femoral heads of 13 dogs undergoing total hip replacement.Rates of glycosaminoglycan (GAG) synthesis and degradation, protein synthesis, cell viability, and prostaglandin release were determined in canine explant cartilage or monolayer canine chondrocyte cultures in the presence of 0 to 100 micrograms of carprofen/ml. Rate of GAG synthesis was assessed as incorporation of [35S]sulfate into cartilage matrix during a 3-hour pulse label. Degradation of cartilage GAG was assessed as rate of release of [35S]sulfate from prelabeled explant cultures. Rates of total protein synthesis were assessed as incorporation of [35S]methionine into trichloracetic acid precipitable material during a 3-hour pulse label. Radiolabeled chondrocyte proteins were separated by polyacrylamide gel electrophoresis and visualized by fluorography. Rates of prostaglandin E2 release were assessed by radioimmunoassay.Carprofen stimulated a significant increase in the rate of GAG synthesis at concentrations of 1 and 10 micrograms/ml, with no change in total protein synthesis, pattern of new protein synthesis, or cell viability. At concentrationor = 20 micrograms/ml, inhibition of GAG synthesis and total protein synthesis was observed. There was no significant change in rate of release of GAG from cartilage explants, but potent inhibition of prostaglandin release was observed.Carprofen has a direct influence on chondrocyte activity, resulting in changes in rate of production of cartilage matrix.In determining the optimal therapeutic dose of carprofen for arthritic conditions in dogs, it is important to consider potential influences on cartilage, as well as anti-inflammatory actions.

Seventy dogs were included in a randomized, controlled, multicenter trial to test the efficacy of carprofen (2.2 mg/kg of body weight, PO, q 12 h) for relief of clinical signs associated with osteoarthritis. Thirty-six dogs received carprofen, and 34 received a placebo. Response of the dogs was evaluated by comparing results of force plate examination and a graded lameness examination performed before and immediately after 2 weeks of treatment, and by obtaining a subjective assessment of the dog's posttreatment condition from owners and participating veterinarians. A physical examination, CBC, serum biochemical analyses, urinalysis, and fecal occult blood test were performed before and after treatment to monitor safety. For force plate evaluation, the odds ratio was 3.3, meaning that a dog treated with carprofen was 3.3 times more likely to have a positive response than was a dog treated with the placebo. For evaluation by a veterinarian, the odds ratio was 3.5, and for owner evaluation, the odds ratio was 4.2. Institution where dogs were treated did not have a significant effect on results. A variety of reactions that may have been related to the medication (placebo or carprofen) were recorded; however, none were considered serious. Serum alanine aminotransferase activity was high in 3 dogs (2 that received placebo and 1 that received carprofen) at the conclusion of treatment; none of the 3 dogs were clinically ill. Ten dogs (5 that received placebo and 5 that received caprofen) had negative pretreatment and positive posttreatment fecal occult blood test results.

Results of total hip arthroplasty in 84 dogs (96 hips) were evaluated. Eight (9.5%) of the 84 dogs developed 1 or more complications after total hip arthroplasty. Complications resolved or were corrected in 4 of the dogs; all 4 ultimately achieved good or excellent hip function. Complications necessitated removal of the prosthesis in the other 4 dogs; 3 ultimately achieved fair hip function and 1 had only poor hip function. Therefore, after resolution of complications, 96% of the hips had good or excellent function. Force plate analysis was performed on 6 dogs with excellent hip function; peak vertical force for the limb that had been operated on was greater than or equal to peak vertical force for the contralateral limb. Radiographically, a radiolucent zone was visible around the acetabular component in 89% of the hips and around the femoral component in 26%. The radiolucent zone around the acetabular and femoral components widened in 14% (6 of 43) and 27% (3 of 11), respectively, of the hips with adequate radiographic follow-up. Aseptic loosening of the acetabular component developed in 3 (3%) of 96 hips; one was successfully revised. Aseptic loosening of the femoral component was not apparent in any of the dogs in this study. Other complications included femoral fracture (n = 3), neurapraxia (3), luxation (1), and unexplained lameness that required implant removal (1). None of the dogs had evidence of wound infection.

Middiaphyseal radial ostectomy was performed in 2 dogs that had premature closure of their distal radial physes. Complications included disuse osteoporosis, carpal hyperextension of the affected and contralateral limbs, degenerative joint disease involving the cubital and carpal joints, synostosis of the radius to the ulna, premature closure of the distal portion of the ulna, and failure to achieve normal limb length. Both dogs were lame after exercise.

The biomechanical and clinical performance of bone-ligament-bone anterior cruciate ligament (ACL) allografts was studied in eight dogs. Allografts were collected from skeletally mature, healthy dogs using aseptic technique, and stored at -70 degrees for three to five weeks before implantation. The allografts were size-matched to the recipient dogs using ACL length and then rigidly fixed in position with interference screws and Kirschner wires. Three dogs regained a normal gait, and their grafts sustained breaking loads that were 25%, 41%, and 59% of controls. Partial or complete graft failure occurred in the other five dogs at some point in the study. Four had intraligamentous rupture and one had an avulsion fracture of the femoral attachment site. Joint-fluid cytology was normal in all eight dogs. Histologic examination showed persistent lymphoplasmacytic infiltrate. Eventually the allograft cores were incorporated in the host bed. Hyperplasia and fibrosis of the synovial membrane were diffuse and persisted as focal accumulations of mononuclear inflammatory cells.

A retrospective study involving 720 dogs and cats that underwent a variety of elective surgical procedures was done to compare the effectiveness of reusable cotton barrier materials with that of a commercially available disposable barrier system for prevention of wound infection. The overall wound infection rate, using cotton barrier materials, was 3.1% and for disposable materials, was 4.4%. The difference between groups was not significant.

Congenital luxation of the shoulder in a 7-month-old Chihuahua was corrected by use of arthrodesis. A single lag-screw fixation technique was used. Arthrodesis of the shoulder provides a favorable alternative to other salvage techniques such as glenohumeral resection or amputation.

The biomechanical and clinical performance of bone-ligament-bone anterior cruciate ligament (ACL) allografts was studied in eight dogs. Allografts were collected from skeletally mature, healthy dogs using aseptic technique, and stored at -70 degrees for three to five weeks before implantation. The allografts were size-matched to the recipient dogs using ACL length and then rigidly fixed in position with interference screws and Kirschner wires. Three dogs regained a normal gait, and their grafts sustained breaking loads that were 25%, 41%, and 59% of controls. Partial or complete graft failure occurred in the other five dogs at some point in the study. Four had intraligamentous rupture and one had an avulsion fracture of the femoral attachment site. Joint-fluid cytology was normal in all eight dogs. Histologic examination showed persistent lymphoplasmacytic infiltrate. Eventually the allograft cores were incorporated in the host bed. Hyperplasia and fibrosis of the synovial membrane were diffuse and persisted as focal accumulations of mononuclear inflammatory cells.

Two thousand sixty-three surgical procedures were performed on 1992 patients (1715 dogs and 277 cats). In a retrospective analysis, the procedures were categorized according to the expected degree of wound contamination, and corresponding wound infection rates were determined. The number of procedures in each category and the percent that became infected were as follows: clean (1100, 2.5%), clean-contaminated (554, 4.5%), contaminated (172, 5.8%), and dirty (237, 18.1%). The administration of antibiotics significantly reduced the frequency of wound infection in clean surgical procedures performed by senior veterinary students (p less than 0.05), but not in clean elective procedures performed by faculty or resident surgeons that required 90 minutes or less to complete. There was a significant correlation between elevation of rectal temperature postoperatively and increased duration of the surgical procedure. However, the rectal temperature measured the day after surgery was not an accurate predictor of wound infection.

Eighty-five dogs were diagnosed as having rupture of the cranial cruciate ligament. They were managed by restriction of activity to leash walks for 3 to 6 weeks, weight loss if indicated, and analgesic medication as needed. Twenty-four of 28 dogs that had a body weight of 15 kg or less (85.7%) were considered to be clinically normal (no lameness and normal range of motion in stifle, 21 dogs) or improved (3 dogs) after an average follow-up period of 36.6 months. Lameness in the remaining four dogs persisted or worsened over an average period of 8.2 months (minimum 6 months), and surgical replacement of the cruciate ligament was performed. Eleven of 57 dogs that had a body weight of 15 kg or greater (19.3%) were classified as normal (4 dogs) or improved (7 dogs) after an average follow-up period of 49.1 months. Lameness in the remaining 46 dogs persisted or worsened over an average period of 10.2 months (minimum 6 months), and surgical replacement of the cruciate ligament was performed.

An osteosarcoma developed in the proximal femur of a 9-year-old female Great Dane. The femur had been fractured 5 years previously and was stabilized with plate fixation with the incorporation of a frozen cortical bone allograft. The dog recovered without complications after the surgery and had normal use of the leg before the osteosarcoma developed. The tumor had metastasized to the lungs, spleen, and ipsilateral popliteal lymph node.

As our knowledge of the disease conditions affecting the airways increases, the opportunity and need to surgically invade these structures will increase accordingly. The importance of a carefully planned and excuted anesthetic protocol cannot be overemphasized; a well trained and experienced individual must monitor patients throughout the procedure and manipulate the anesthesia as required. With the use of current anesthetic equipment and techniques, the surgical correction of tracheal disorders can be accomplished safely.

Perineal urethrostomies were performed on 35 cats. All cats were asymptomatic when examined an average of 48.4 months following surgery. Eleven cats (31%) had episodes of dysuria during the postoperative period. Two of the 11 and six additional cats (23%) had positive urine cultures (> 105 organisms/ml) at the time of examination.

The stability of the canine shoulder joint was assessed with and without the restraining effects of selected supporting structures. Shoulder joints from medium-sized (15 to 30 kg) canine cadavers were dissected, and all soft tissues were removed except for the 4 cuff muscles (supraspinous, infraspinous, teres minor, subscapular), the biceps muscle (m biceps brachii) and the joint capsule with its associated glenohumeral ligaments. The humerus was fixed in position, and with the shoulder extended, the joint was stressed into abduction, adduction, internal rotation, and external rotation. The range of motion was measured from transverse pins placed above and below the joint. Measurements were made before and after severance of the cuff tendons and joint capsule. In selected joints, medial and lateral luxations were created. The biceps tendon was then transposed medially or laterally, respectively, to aid joint stability. Selected medial luxations were stabilized by transferring a portion of the insertion of the supraspinous tendon to a medial location. All joints were stressed as just described, and the range of motion was measured before and after tendon transfer. The joint capsule with its associated glenohumeral ligaments was an important restraint of joint motion. Lateral transfer of the biceps tendon partially corrected lateral joint instability by imposed marked rotational constraints on the joint. Medial transfer of the biceps tendon or the supraspinous tendon partially corrected medial joint instability, but did not resolve rotational abnormalities.

The influence of lidocaine and bupivacaine on the breaking strength and histopathologic appearance of wounds in the ventral abdominal midline (linea alba) of rabbits was studied. In control rabbits, group 1 (n = 24), skin and subcutaneous tissues were incised, permitting direct infiltration of the linea alba with normal saline solution. The linea alba was then incised, and wound margins were apposed in layers, using absorbable suture material. Group 2 rabbits (n = 24) were given 0.5% lidocaine, group 3 rabbits (n = 24) were given 2% lidocaine, and group 4 rabbits (n = 24) were given 0.5% bupivacaine, rather than saline solution. Eight rabbits from each group were killed 6, 12, and 18 days after wounding. Eight 1.0-cm wide transverse strips were removed from the abdominal wall of each rabbit. Two strips were used for histopathologic evaluation and 6 were tested for failure, using a mechanical testing device. Breaking strengths in group 1 averaged 0.66 kg, 1.35 kg, and 1.57 kg at 6, 12, and 18 days, respectively. None of the test groups had significantly different (P greater than 0.05) breaking strength results as compared with that in controls. The histopathologic appearance of tissues infiltrated with local anesthetics did not vary consistently from that of tissues infiltrated with normal saline solution. Local infiltration of lidocaine and bupivacaine does not alter substantially the healing of midline abdominal incisions in rabbits.

Ligaments of the lower cervical spine (C3 to C7) were studied in 27 canine cadavers. The gross anatomy and attachment sites were determined by dissection, and representative samples of the flaval ligament, facet capsules, and dorsal longitudinal ligament were examined by light microscopy and were stained for elastin content. Selected functional spinal units were placed in a specially constructed humidification chamber and were fixed in position, using methyl methacrylate bone cement. The specimens were stressed in flexion and extension, and vertebral displacement was measured before and after severance of the spinal ligaments. The flaval ligament had a marked elastin content and contained randomly oriented collagen bundles. The dorsal longitudinal ligament possessed a negligible elastic fiber content and demonstrated longitudinally oriented collagen bundles. The facet capsules possessed an inner synovial lining and outer fibrous layer typical of synovial joint capsules. In general, the severance of spinal ligaments resulted in small increments of displacement until failure occurred, which was often sudden and complete. The flaval ligament, facet capsules, dorsal longitudinal ligament, and intervertebral disk were the major ligamentous stabilizers of the lower cervical spine.

Surgical techniques for correcting medial or lateral instability of the scapulohumeral joint in conditioned research dogs were evaluated. Lateral instability was created by severing the lateral joint capsule and the tendon of insertion of the infraspinatus muscle. In 4 dogs, the tendon of origin of the biceps brachii muscle was then transferred to a position lateral to the greater tubercle in an effort to improve lateral stability. In 3 control dogs, lateral instability was induced, but attempt was not made to stabilize the joint. Medial instability was created by severing the tendon of insertion of the subscapularis muscle and the medial joint capsule. In 3 dogs, the tendon of origin of the biceps brachii muscle was transferred to a position under the lesser tubercle. In 2 dogs, a portion of the tendon of insertion of the supraspinatus muscle was transferred to a medial location. In 3 control dogs, attempt was not made to stabilize the joint. The control dogs (n = 6) demonstrated mild-to-moderate weight-bearing lameness for 7 to 14 days after surgical induction of joint instability and thereafter had normal limb usage. Dogs having had tendon transfer procedures recovered normal limb usage in 4 to 6 weeks and thereafter behaved normally. At necropsy, all joints appeared stable, and the surgical repairs were intact. A variety of joint surface abnormalities consistent with degenerative joint disease was observed, but no consistent pattern was assignable to any given surgical manipulation.

Acute replacement of the canine anterior cruciate ligament (ACL) with a frozen, bone-ligament-bone anterior cruciate ligament preparation was studied using biochemical, immunologic, and biomechanical testing methods. Nine dogs were used for the study, six dogs received allografts and three received autografts. No tissue antigen matching was performed. All nine dogs were killed nine months after surgery. Necropsy examination revealed that the ACL was not present in three joints (one autograft, two allografts). The two autograft and four allograft ligaments available for mechanical testing sustained mean maximum loads that were 10% and 14%, respectively, of the mean maximum loads sustained by the contralateral ACL. Autoradiography indicated that cellular activity was more pronounced in the autograft specimens. Hydroxyproline uptake was 200% and 45% of normal in the autograft and allograft ligaments, respectively. Both autograft and allograft specimens were producing Type I collagen at the time of killing. Antidonor dog leukocyte antigen (DLA) antibody was detected in the synovial fluid taken at the time of killing from six of six dogs that received allografts and in zero of three dogs that received autografts.

A total of 122 dogs and 7 cats were included in a prospective, randomized, blind trial to determine the frequency of wound infection after clean surgical procedures and to compare the infection rates in dogs and cats given ampicillin (group 1) with those given a placebo (group 2). The 2 groups were similar in terms of mean age, sex ratio, duration of hospital stay, and types of surgical procedures. A wound infection developed in one of the dogs given ampicillin; there were no wound infections in the animals given the placebo. The infection rates in the 2 groups were not significantly different.

Urethral pressure and electromyographic profiles were recorded in 10 healthy adult male cats before and after perineal urethrostomy. There was a significant decrease (P = 0 at 1 week after surgery, P = 0.002 at 3 weeks after surgery) in the mean maximum urethral pressure profile with associated loss of periurethral striated muscle activity.

Tissue and swab specimens for bacteriologic culture were obtained from the operative wound in 40 dogs in which plates and screws were applied and then removed from the sites of healed fractures or arthrodeses. Implants were removed after a mean (+/- SD) application period of 15.7 +/- 9.3 months. Bacteria were isolated from the plate-bone interface in 17 dogs. Of the 17 dogs, 9 had had complications associated with initial management (eg, osteomyelitis, open fractures, or multiple surgical procedures). Control specimens were obtained from 30 dogs that had clean elective orthopedic procedures that did not involve implantation of metallic prostheses. None of the dogs of the control group were given antibiotics. Bacteria were isolated from 2 of 30 specimens obtained from control dogs. The difference between the number of culture-positive specimens from dogs of the implant group and those from dogs of the control group was significant (P less than 0.01).

The anatomic features and functions of the collateral ligaments of the canine stifle joint were investigated, using cadaver specimens. The structure of the collateral ligaments was examined by dissection, with attention given to the spatial relationships existing between the collateral ligaments and their neighboring structures, such as the menisci and joint capsule. The relative tension of the ligaments was determined by identifying the points of attachment with lead markers and taking a series of radiographs of the joint throughout its range of motion. The distance between the points was measured, and the change in length was determined as a function of joint position. Measurements of internal and external rotation, varus angulation, and valgus angulation were made before and after severance of one or both ligaments. The medial collateral ligament was taut in extension, with only the caudal portion of the ligament becoming lax in flexion. The lateral collateral ligament was also taut in extension; however, its entire bulk because lax as the joint was flexed. In extension, the ligaments were primary restraints preventing varus and valgus angulation, and they functioned to limit internal and external rotation of the tibia. In flexion, the cranial portion of the medial collateral ligament remained taut and prevented external rotation of the tibia, whereas the relaxation of the lateral collateral ligament allowed the tibia to rotate internally, with further rotation limited by the cruciate ligaments.U

To compare the efficacy of allograft versus autograft replacement of the anterior cruciate ligament, 15 dogs had the ligament cut and replaced 1 month later: 11 dogs received a frozen bone-ligament-bone allograft cruciate ligament, while 4 dogs received a standard autogenous replacement with iliotibial band. Three of 11 allograft dogs developed postoperative infections and were removed from the study; and two of the remaining eight allograft ligaments were absent at autopsy. All the autograft ligaments were present. From serial clinical and radiographic examinations, there were no differences observed in the two groups. Autopsy studies at 4 months, however, showed an increased inflammatory, pannus-like reaction about the origins and insertions of the six allograft ligaments as compared with the four autografts. The ligament hydroxyproline uptake was lower in the allograft group, averaging 60 percent of the contralateral unoperated on control versus equal to the control in the autograft group. The tensile strength of the allografts reached only 17 percent of the control value versus 41 percent for the autografts. Lymphocytotoxicity testing at 1 month revealed a donor-specific antibody response in 4 of 8 allograft dogs; however, no histologic evidence of immune response was observed in the ligaments. The synovial fluid leukocyte count was elevated in the allograft group at 4 months. The increased synovial leukocyte counts and joint cartilage erosion, the decreased strength and metabolic activity of the grafts, and the evidence of an immune response in the allograft dogs do not support implantation of cadaver cruciate ligaments clinically at this time.

Osteochondritis dissecans of the medial aspect of the talus was diagnosed in 17 joints in 11 dogs. In 10 of the 11 dogs, intermittent lameness had persisted after initial diagnosis and therapy. Radiographs made during the initial examination showed a widening of the medial tarsocrural joint space, with osteophyte formation involving the medial and caudal tarsocrural joint. The follow-up radiographs showed greatest change in the increase in reactive bone formation, especially involving the medial and caudal aspects of the tarsocrural joint and the medial aspect of the talus. Arthrotomy for flap removal and curettage was performed on 11 joints; 6 joints did not receive surgery. After a mean period of 34 months following diagnosis, the dogs were examined clinically and the affected joints were radiographed. The degree of lameness, range of motion, and stability of the tarsocrural joint were graded for each limb. Radiographic determinants that were assessed included: width of the medial tarsocrural joint space, medial tarsocrural osteophyte formation, lateral tarsocrural osteophyte formation, caudal tarsocrural osteophyte formation, medial talus osteophyte formation, lateral talus osteophyte formation, intertarsal osteophyte formation, subchondral sclerosis of the distal end of the tibia, presence of joint bodies, and periarticular soft-tissue thickness. On the basis of clinical and radiographic evaluations, the surgical procedures described in this report did not modify progression of osteoarthritic changes.

Twenty-six dogs had lateral ear resection performed for the treatment of chronic otitis externa. After a mean follow-up period of 4.5 years, 17 of the 26 dogs were available for physical examination. The remaining 9 dogs died prior to this review; their owners were surveyed by questionnaire. In the examined group, the resolution of clinical signs was good in 41% of the dogs, improved in 12%, and poor in 47%. A good result was defined as the elimination of clinical signs, with minimal or no care required from the owner. An improved status was assigned to dogs that experienced occasional recurrence of signs requiring professional attention. A poor result was defined as no improvement.

A test mating between two Manchester Terriers affected by Perthes' disease (PD) resulted in the birth of three affected males and two unaffected females. In the three puppies with PD, roentgenographically detectable changes in the affected femurs were observed two to three weeks before the onset of lameness and muscle atrophy in the corresponding limb. Analysis of the related pedigrees and of the results of the test mating indicated that PD is an inherited condition with high heritability.

The effectiveness of various fixation techniques in preventing rotation of fracture segments in transverse fractures of the canine femoral diaphysis was evaluated under laboratory conditions. Single intramedullary Steinmann pins, single Küntscher nails, multiple intramedullary Steinmann pins, and an intramedullary Steinmann pin with a 1/2 Kirschner splint fixation sustained mean torque moments of 0.31, 0.61, 1.26, and 1.63 Newton meters, respectively, before rotation of the fracture segments occurred. Four-pin (full Kirschner) splints were more effective, sustaining a mean torque moment of 5.35 Newton meters before rotation occurred. The canine femoral medullary canal had an average isthmus length of 2.0 to 2.5 cm. The restricted area of implant-cortex contact limited the effectiveness of the intramedullary fixation devices in preventing fracture segment rotation.

Thirty-four dogs that had surgical correction of medial patellar luxation (MPL) in 52 stifle joints were examined after a minimum follow-up period of 1 year (median, 3.6 years). The dogs were divided into the following three groups depending on their age at the time of surgery: group 1, 3 to 6 months; group 2, 8 to 20 months; and group 3, 2.2 to 12 years. Two of the dogs in group 3 had ruptured their cranial cruciate ligament in addition to having MPL. The results were based on a clinical assessment of the animal's gait, and physical and radiographic examination of the stifle joints. Six of seven stifle joints evaluated in group 1 had radiographic evidence of moderate to severe degenerative joint disease of the patellofemoral joint, and in two of the joints recurrence of MPL was observed. Failure to maintain reduction of the patellofemoral joint was also observed in 11 of 22 (50%) and 12 of 23 (52%) of the stifle joints in groups 2 and 3, respectively. In the latter groups, mild degenerative joint disease was evident radiographically in stifle joint that had not maintained reduction. Four of the 34 dogs were consistently (n = 2) or intermittently (n = 2) lame; the two dogs that were consistently lame had cranial instability of the stifle consistent with rupture of the cranial cruciate ligament. In the latter two dogs, the cranial cruciate ligament had been intact at the time of surgery for correction of MPL.

Limb salvage was accomplished by using a frozen allograft bone and arthrodesis of the stifle joint in a 5-year-old male German Shepherd Dog with a chondrosarcoma in the proximal tibia. At 17 months after surgery, limb function was satisfactory, and thoracic radiography did not reveal evidence of pulmonary metastases.

The mechanical properties of the cranial cruciate ligament were determined, using unilateral bone-ligament-bone preparations from 65 dogs of various ages and body sizes. Tensile loading of the cranial cruciate ligament from 1 of each pair of stifle joints demonstrated a decrease in material properties (modulus, maximum stress, strain energy) with aging. The decreases in maximum stress and strain energy with age were significantly less (P less than 0.05 and P less than 0.05, respectively) in the cranial cruciate ligament from dogs weighing less than 15 kg, compared with those weighing 15 kg or more. The cranial cruciate ligament and remaining femorotibial ligaments were collected from the opposite stifle joints and examined microscopically. By 5 years of age, the cranial cruciate ligaments of dogs weighing greater than 15 kg consistently had microscopic evidence of degenerative disease (loss of ligamentocytes, metaplasia of surviving ligamentocytes to chondrocytes, and failure to maintain collagen fibers and primary collagen bundles) which progressed in severity with age. The caudal cruciate ligaments were similarly affected, although the degenerative changes were rarely as severe as in the cranial cruciate ligament. The collateral ligaments underwent minimal degeneration. Sex differences had no bearing on degeneration. The cranial cruciate ligaments in dogs weighing less than 15 kg generally had less severe alterations than those in heavier dogs, and the onset of the degenerative process was delayed by several years. Cranial cruciate ligaments removed from dogs after ligament failure not only had degenerative disease, but also had undergone unsuccessful attempts at repair. In contrast, fibrous repair was rarely present in intact ligaments of asymptomatic dogs with degenerative disease of the cranial cruciate ligament.