Evaluation of crural release and ischial osteotomy for relief of tension in the repair of large segmental urethral defects in male cats.

OBJECTIVE: To examine if the tension at the site of a urethral anastomosis can be relieved by performing either a crural release technique or an ischial osteotomy technique. STUDY DESIGN: Cadaveric study and 2 case reports. ANIMALS: Adult male cat cadavers (n = 18). METHODS: Cats were divided into 2 groups; crural release (n = 9) and ischial osteotomy (n = 9). In each group, 20%, 25%, and 30% of the pelvic urethra was excised in 3 cats. The length of the urethral defect was measured after excision of the urethral segment, and after approximation, before and subsequent to the tension relieving technique performed. Two clinical cases are described. RESULTS: Both crural release and ischial osteotomy were effective in relieving the tension encountered at the urethral anastomosis after removal of 20% of the urethral length. In the ischial osteotomy group, apposition without tension after removing up to 30% of the intrapelvic urethral length was easily achieved. A similar technique was successfully used in 2 clinical cases. CONCLUSION: Crural release and ischial osteotomy techniques allow approximation and tension free anastomosis of large segmental defects of the pelvic urethra in cats.

Normograde and retrograde pinning of the distal fragment in humeral fractures of the dog.

OBJECTIVE: To determine if normograde and retrograde pinning of the distal humeral fragment, to maximize pin purchase in this fragment, would damage vital structures in and around the elbow and shoulder joints in dogs. STUDY DESIGN: Anatomic study. SAMPLE POPULATION: Cadaveric dogs (n = 12; 12 thoracic limb pairs). METHODS: Twelve thoracic limb pairs were harvested from cross-breed dogs and 1 thoracic limb from each pair was allocated to 1 of 3 groups. A transverse osteotomy was created at the junction of the middle and distal thirds in the diaphyseal fracture group (n = 8) and proximal to the supracondylar foramen in the metaphyseal fracture group (n = 8). The humeri in the normograde group (n = 8) were left intact. In all specimens in the distal and supracondylar fracture groups, retrograde pinning of the distal fragment was performed with the elbow flexed. The pins were driven into the medial epicondyle until they exited the skin caudal to the elbow. Dissection of the soft tissues around the exit tract of the pin was performed. The fracture was then reduced and the pin was advanced until it exited the proximal humeral fragment. In the specimens in the normograde group, pinning was initiated on the distal aspect of the medial epicondyle. The pin was directed parallel to the caudal aspect of the medial epicondyle and driven proximally into the humerus until it exited the proximal humerus. RESULTS: Pins exiting the distal aspect of the medial epicondyle passed through muscle origins in 7 specimens in the diaphyseal osteotomy group and in all 8 specimens in the metaphyseal group. The ulnar nerve was entrapped in 1 specimen in the metaphyseal osteotomy group; however, it was not entrapped in any of the specimens in the diaphyseal osteotomy group. The articular cartilage of the trochlea was damaged in 2 specimens in each of the retrograde pinned groups. There was no damage to articular or periarticular structures by pins exiting the proximal humerus. CONCLUSION: Retrograde pinning of the distal fragment in humeral fractures in the dog may damage the articular cartilage and cannot be recommended.

Normograde and retrograde pinning of the distal fragment in feline humeral fractures.

OBJECTIVE: To determine if normograde and retrograde pinning of the distal humeral fragment, performed to maximize pin purchase in this fragment, would damage vital structures in and around the elbow and shoulder joints in cats. STUDY DESIGN: Anatomic study. SAMPLE POPULATION: Cadaveric cats (n = 12; 24 thoracic limbs). METHODS: Twelve thoracic limb pairs were harvested from domestic short-haired cats and 1 limb from each pair was allocated to 1 of 3 groups. A transverse osteotomy was created at the junction of the middle and distal thirds in the diaphyseal osteotomy group (n = 8) and proximal to the supracondylar foramen in the metaphyseal osteotomy group (n = 8). Humeri in the normograde group (n = 8) were left intact. Retrograde pinning of the distal fragment in both osteotomy groups was performed with the elbow flexed. Pins were driven into the medial epicondyle until they exited the skin caudal to the elbow and dissection of the soft tissues around the exit tract of the pin was performed. The fracture was reduced and the pin was advanced until it exited the proximal humeral fragment. In the specimens in normograde group, pinning was initiated on the distal aspect of the medial epicondyle. A 1.0 mm guide hole was drilled from the medial epicondyle to the center of the medullary cavity of the distal humeral metaphysis. A bevelled 1.5 mm IM pin was driven proximally through the guide hole until it exited the proximal humerus. RESULTS: Pins exiting the distal aspect of the medial epicondyle passed through muscle origins in 5 specimens in the diaphyseal osteotomy group and in all 8 specimens in the metaphyseal group. The ulnar nerve was entrapped in 1 specimen in both the metaphyseal osteotomy and diaphyseal osteotomy groups. The articular cartilage of the trochlea was damaged in 5 specimens in the diaphyseal osteotomy group and in 1 specimen in the metaphyseal osteotomy group. There was no damage to articular or periarticular structures by pins exiting the proximal humerus. CONCLUSION: Retrograde pinning of the distal fragment in humeral fractures in the cat may damage the articular cartilage and cannot be recommended. Normograde pinning is safe and maximizes pin purchase in the distal fragment.

Axial pattern flap based on a cutaneous branch of the facial artery in cats.

OBJECTIVE: To describe the cutaneous portion of the facial artery in cats and an axial pattern flap based on a branch of this artery. STUDY DESIGN: Ex vivo study. SAMPLE POPULATION: Cat cadavers (n=12). METHODS: The common carotid artery was identified, cannulated, and infused with methylene blue to assist in the identification of the facial artery, which was subsequently cannulated and selectively infused with methylene blue. The main trunk of the artery and its branches were dissected. The extent of blue coloration of the skin was evaluated on the contralateral side of the same specimen after infusing methylene blue into the facial artery. In 4 specimens, the flap was raised along previously defined borders and adequacy of perfusion was evaluated. RESULTS: The area of skin perfused by the facial artery extended from the lower eyelid dorsally, to the angularis oris cranially, and the wing of the atlas caudally. Borders of the skin flap were defined on the basis of the anatomic dissection and skin coloration after selective infusion of the facial artery with methylene blue. A skin flap of 6 cm × 3.4 cm, based on the first caudally directed cutaneous branch of the facial artery was shown to be well perfused. The viability of this flap was confirmed in a clinical case. CONCLUSION: The facial artery flap is useful for repair of skin defects of the head in cats.

Lateral thoracic artery axial pattern flap in cats.

OBJECTIVE: To describe the location of the lateral thoracic artery (LTA), determine dimensions of an axial pattern flap based on this artery, and report use of this flap in 2 cats. STUDY DESIGN: Ex vivo study and case reports. ANIMALS: Cat cadavers (n=8); cats (n=2) with thoracic limb skin defects. METHODS: Dissection of the LTA was carried out on 1 side of each cadaver and the contralateral side was used for injection studies. In 4 specimens, the LTA was cannulated and injected with positive contrast material and the flap was raised and radiographed. In 4 specimens, the flap was injected with methylene blue. Adequacy of flap injection was subjectively evaluated and leakage of methylene blue from the cut edge was noted. RESULTS: The cutaneous location of the LTA caudal to the triceps muscle was confirmed. Mean flap size was 8.7 cm x 15.5 cm for a mature, average-sized cat. Perfusion of the entire flap was demonstrated and viability of the flap was confirmed in 2 clinical cases. CONCLUSION: The LTA flap is useful for repair of skin defects of the brachium and antebrachium in cats. CLINICAL RELEVANCE: The LTA flap is an alternative technique for repair of skin defects involving the thoracic limb of cats.