In vitro comparison of two centrally threaded, positive-profile transfixation pin designs for use in third metacarpal bones in horses.

OBJECTIVE: To compare heat generation during insertion, pullout strength, and associated microdamage between a self-tapping positive profile transfixation pin (STTP) and nontapping positive profile transfixation pin (NTTP). SAMPLE POPULATION: 30 pairs of third metacarpal bones (MC3s) from adult equine cadavers. PROCEDURES: One MC3 of each pair was assigned to the STTP group; the other was assigned to the NTTP group. The assigned pin was inserted into the diaphysis in a lateral to medial direction. Bone temperature increase during pilot-hole drilling and pin insertion was recorded at 1 mm from the final thread position with wire thermocouples at cis and trans cortices. Resistance to axial extraction before and after cyclic loading was measured in a material testing device, and microstructural damage caused by transfixation pin insertion was assessed with scanning electron microscopy. RESULTS: The STTP group developed a significant increase in bone temperature, compared with the NTTP group. No significant difference was found between the mean maximal pullout strength of the STTP and the NTTP in both non-cyclic-loaded and cyclic-loaded groups. Microdamage to the bone-pin interface was lower when the STTP versus the NTTP was used, but more bone debris was apparent after inserting the STTP. CONCLUSION AND CLINICAL RELEVANCE: Because of the significant increase in temperature generation and debris accumulation despite similar pullout strengths and lesser microfracture formation, the STTP likely poses a higher risk of bone necrosis and potential loosening than the NTTP. This might be corrected by redesign of the tapping aspect of the STTP.

Surgical management of small intestinal incarceration through the gastrosplenic ligament: 14 cases (1994-2006).

OBJECTIVE: To determine prevalence, clinical findings, and long-term survival rate after surgery associated with incarceration of the small intestine through the gastrosplenic ligament (ISIGL) in horses. DESIGN: Retrospective case series. ANIMALS: 14 horses with ISIGL. PROCEDURES: Medical records of horses with ISIGL examined between January 1994 and December 2006 were reviewed. Signalment, initial physical examination findings, results of abdominal fluid analysis, and clinical laboratory values were recorded, along with surgical findings, including segment of incarcerated intestine and surgical procedures performed. Long-term survival data were obtained through client interviews. RESULTS: Clinical findings included small intestinal distention identified via rectal palpation (10/14 horses) or transabdominal ultrasonography (8/11), nasogastric reflux (4/14), and abnormal abdominal fluid (9/9). All horses required intestinal resection and anastomosis. Postoperative complications included adynamic ileus (5/14 horses), incisional infection (4/14), diarrhea (3/14), and laminitis (1/14). No breed or age predilection was detected, although geldings were at increased risk for ISIGL. Long-term survival rate was 79% (11/14 horses). CONCLUSIONS AND CLINICAL RELEVANCE: ISIGL was an uncommon cause of colicin this hospital population. With appropriate surgical intervention and postoperative management, the long-term prognosis for surgically treated horses was fair to good.