Computed tomographic evaluation of comminuted middle phalangeal fractures in the horse.

Comminuted fractures of the middle phalanx have been well described in the horse. Choice of treatment, surgical planning and prognosis have traditionally been based upon evaluation of radiographs. However, the complex nature of comminuted fractures makes radiographic interpretation difficult. Computed tomography (CT) allows the production of cross-sectional images with spatial separation of structures which are superimposed on survey radiographs. This allows accurate assessment of the number and direction of fracture lines within the bone. In this paper we report the use of CT in the evaluation of 6 comminuted middle phalangeal fractures. Computed tomography is potentially useful in deciding the type of treatment, surgical planning and determining the prognosis.

Use of intraoperative ultrasonography in six horses.

Intraoperative ultrasonography was used in six horses to aid localization and removal of bone fragments (3 horses) and foreign bodies (3 horses). The ultrasound transducer was enclosed in a sterile sleeve containing sterile aqueous gel and the examination was performed after aseptic preparation of the surgical site. Using ultrasound guidance a needle was placed in contact with the bone fragment or foreign body and an incision was made along the path of the needle to expose and remove the object. This technique resulted in decreased operative time and minimal tissue dissection.

Resection and anastomosis for treatment of strangulating volvulus of the large colon of horses.

Strangulating volvulus of the large colon was treated by resection and anastomosis of the colon in 9 horses. Tissue specimens were obtained at the site of the resection for histologic evaluation. An attempt was made to correlate the appearance of the colon at the time of surgery to the histologic evaluation and the eventual outcome. Six of the 9 horses (66%) survived. This is in contrast to a reported survival of 34.7 to 36% after decompression and reduction of colonic volvulus. Survival after surgery could not be predicted on the basis of visual assessment or histologic examination.

Thermal modeling of polymerizing polymethylmethacrylate, considering temperature-dependent heat generation.

A methodology for the modeling of unsteady heat conduction in polymethylmethacrylate (PMMA) during its exothermic polymerization is presented. The emphasis is on the formulation of a model for the volumetric rate of heat generation, including its temperature-dependent characteristics. Three parameters appear in the proposed model. The empirical determination of these parameters using Differential Scanning Calorimetry is demonstrated. The incorporation of the proposed model into finite volume methods is also demonstrated, in the context of unsteady, one-dimensional, radial heat conduction in cylindrical coordinates. In addition, the application of the proposed model to two test problems is presented and discussed. The results are encouraging, and the proposed methodology appears to be applicable to the thermal modeling of exothermic polymerization processes in general.

Surgical correction of strictures of the large colon in three horses.

An extensive stricture of the left dorsal colon in a Thoroughbred colt was resected and the colon was anastomosed. In two horses, circumferential strictures at the pelvic flexure 2.5 to 3 cm long were corrected with a modified Heineke-Mikulicz pyloroplasty technique. The horses were reported to be doing well at 6, 8, and 45 months, respectively.

Effect of beta-tricalcium phosphate in surgically created subchondral bone defects in male horses.

beta-Tricalcium phosphate (TCP) was evaluated as a synthetic bone grafting material in horses. Sixteen horses were randomly assigned to 4 groups of 4 horses. In each horse, an 11-mm by 10-mm circular defect with a smooth margin was created surgically in the weight-bearing surface of both third metacarpal bones (McIII) and the left third metatarsal bone. The defect in the left McIII was filled with TCP, the defect in the right McIII was filled with a mixture of 50% autogenous cancellous bone (ACB) and 50% TCP, and the defect in the left third metatarsal bone was not filled to serve as a control. Nuclear imaging and radiographic evaluation of surgical sites were performed at postsurgical week (PSW) 4 and 13 in group-I horses and at PSW 26, 39, and 52 in groups-II, -III, and -IV horses, respectively. Horses in groups I, II, III, and IV were euthanatized at PSW 13, 26, 39, and 52, respectively, and specimens were harvested for histologic evaluation. Results were compared among treatment methods, as well as among time intervals. The greatest activity at defect sites was seen in group-I horses at PSW 4. Activity counts in limbs of group-I horses at PSW 13 and counts in limbs of group-II horses at PSW 26 were not significantly (P less than or equal to 0.05) different. Activity counts in groups-III and -IV horses at PSW 39 and 52, respectively, were less than those in groups I and II. However, there was no significant difference in activity counts between limbs implanted with TCP or ACB:TCP.(ABSTRACT TRUNCATED AT 250 WORDS)

Radionuclide, radiographic, and histomorphometric evaluation of healing of surgically created subchondral defects in equine bone.

In the present study, radionuclide scintigraphy and radiography were used to evaluate the rate and degree of healing that occurred in surgically created subchondral bone defects in horses. Following radionuclide scintigraphy and radiography the horses were killed, and histomorphometric analysis was performed on the defect sites. The histomorphometric results were compared to the radionuclide scintigraphic and radiographic results to determine which noninvasive technique provided the most accurate information concerning healing of the bone defects. It was concluded that radionuclide scintigraphy and radiographic evaluation seemed equally well suited for use in serial evaluation of healing of surgically created bone defects. However, it was felt that the most accurate assessment of healing of the bone defects and effects in the adjacent bone could be provided by combining the two methods of evaluation.

Femoral fracture repair complicated by vascular injury in a foal.

A comminuted, mid-diaphyseal femoral fracture was diagnosed radiographically in a 4-month-old Quarter Horse colt. Disruption of the distal blood supply was suspected, as evidenced by coolness and diminished pulses of the distal portion of the limb. The fracture was repaired by compression plating but the foal's condition continued to deteriorate. A femoral arteriogram of the affected limb was obtained. Positive contrast agent was visible only as far as the mid-shaft of the femur. The foal was euthanatized and the postmortem examination revealed a transected popliteal artery accounting for ischemic necrosis of the distal limb.