Effect of width of disk fenestration and a ventral slot on biomechanics of the canine C5-C6 vertebral motion unit.

OBJECTIVE: To investigate the effects of disk fenestration and ventral slot formation on vertebral motion unit (VMU) range of motion (ROM) and determine the effects of fenestration and ventral slot width on VMU ROM. SAMPLE POPULATION: C5-C6 VMUs from 10 skeletally mature canine cadavers. PROCEDURES: Specimens were assigned to 2 groups (5 specimens/group). Surgery was performed in which width of a fenestration and a ventral slot was 33% (group 1) or 50% (group 2) the width of the vertebral body. Flexion-extension, lateral bending, and axial torsion ROMs were measured during loading before surgery, after fenestration, and after ventral slot formation. Range of motion was compared within groups to determine effects of surgical procedure on stability and between groups to determine effects of width of fenestration and ventral slot on stability. RESULTS: For both groups, fenestration resulted in a significant increase in ROM during flexion-extension, compared with results for intact specimens. Ventral slot formation resulted in a significant increase in ROM during flexion-extension and lateral bending, compared with results for intact specimens. Ventral slot formation resulted in a significant increase in ROM only during flexion-extension, compared with results for fenestrated specimens. There were no significant differences in ROM of the intact, fenestrated, and ventral slot specimens between groups. CONCLUSIONS AND CLINICAL RELEVANCE: Analysis of these results suggests that fenestration and ventral slot procedures each affect the biomechanics of the C5-C6 VMU. Width of a fenestration or ventral slot up to 50% of the width of C5-C6 may be clinically acceptable.

Extraskeletal osteosarcoma associated with retained surgical sponge in a dog.

Retained surgical sponges are usually discovered in the abdominal cavity, sometimes years after the surgical procedure, and the typical reaction is formation of a foreign-body granuloma, often called gossypiboma or textiloma. In this instance, an extraskeletal osteosarcoma, associated with the granulomatous reaction to a retained surgical sponge adjacent to the stifle, was diagnosed in an 11-year-old Labrador Retriever 9 years after repair of a ruptured cranial cruciate ligament. Radiographic detection of linear foreign material in the soft tissue mass was the basis for a diagnosis of gossypiboma. The mass was surgically excised. Histologically, fibers consistent with those of cotton gauze were associated with the granulomatous inflammation and the osteosarcoma. Amputation or radiation therapy was declined; the dog was treated conservatively with doxycycline and deracoxib. Three months after surgical excision, the dog was euthanized because of local recurrence of the mass along with lameness and decreased appetite.

Clinical evaluation of caudal superficial epigastric axial pattern flap reconstruction of skin defects in 10 dogs (1989-2001).

Ten dogs with caudal superficial epigastric axial pattern flap reconstruction of extensive skin defects were reviewed. Nine dogs had complete survival of the flap. In one dog, a small area of necrosis occurred near the flap tip. Other complications included seroma formation (n=3), partial incisional dehiscence (n=3), flap edema (n=9), and bruising (n=7). Use of the caudal superficial epigastric axial pattern flap provided full-thickness skin coverage of extensive skin defects of the rear limb and inguinal region, with relatively minor complications that were amenable to conservative management.

Short-term outcome after total elbow arthroplasty in dogs with severe, naturally occurring osteoarthritis.

OBJECTIVE: To evaluate limb function in client-owned dogs before and after total elbow arthroplasty (TEA) for severe, naturally occurring osteoarthritis (OA). STUDY DESIGN: Prospective clinical evaluation comparing limb function before and after surgery. ANIMALS: Twenty adult, large breed dogs with elbow OA. METHODS: Physical, radiographic, and force platform gait examinations were performed on all dogs before surgery. TEA was performed, and examinations were repeated at 3, 6, and 12 months after surgery. Pre- and postoperative findings were compared. RESULTS: TEA led to a satisfactory outcome in 16 dogs. In dogs with a satisfactory outcome, function in the operated limb increased over time, with mean peak vertical force (PVF) and vertical impulse (VI) 1 year after surgery being nearly twice the presurgical value. Serious complications encountered included infection (n = 2), luxation (n = 1), and fracture of the humeral condyle (n = 1). CONCLUSIONS: Although TEA, as presented, has significant limitations, it can be successfully performed in dogs with naturally occurring elbow OA. Improvements in technique and implant design should lead to improved prognosis. CLINICAL RELEVANCE: Based on 1-year data, TEA can be successfully performed in dogs and should be considered as a treatment alternative for adult dogs with lameness from severe OA of the elbow joint.

Effect of bone diameter and eccentric loading on fatigue life of cortical screws used with interlocking nails.

OBJECTIVE: To test the effects of bone diameter and eccentric loading on fatigue life of 2.7-mm-diameter cortical bone screws used for locking a 6-mm-diameter interlocking nail. SAMPLE POPULATION: Eighteen 2.7-mm-diameter cortical bone screws. PROCEDURE: A simulated bone model with aluminum tubing and a 6-mm-diameter interlocking nail was used to load screws in cyclic 3-point bending. Group 1 included 6 screws that were centrally loaded within 19-mm-diameter aluminum tubing. Group 2 included 6 screws that were centrally loaded within 31.8-mm-diameter aluminum tubing. Group 3 included 6 screws that were eccentrically loaded (5.5 mm from center) within 31.8-mm-diameter aluminum tubing. The number of cycles until screw failure and the mode of failure were recorded. RESULTS: An increase in the diameter of the aluminum tubing from 19 to 31.8 mm resulted in a significant decrease in the number of cycles to failure (mean +/- SD, 761,215 +/- 239,853 to 16,941 +/- 2,829 cycles, respectively). Within 31.8-mm tubing, the number of cycles of failure of eccentrically loaded screws (43,068 +/- 14,073 cycles) was significantly greater than that of centrally loaded screws (16,941 +/- 2,829 cycles). CONCLUSIONS AND CLINICAL RELEVANCE: Within a bone, locking screws are subjected to different loading conditions depending on location (diaphyseal vs metaphyseal). The fatigue life of a locking screw centrally loaded in the metaphyseal region of bone may be shorter than in the diaphysis. Eccentric loading of the locking screw in the metaphysis may help to improve its fatigue life.