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Summary

Biomechanical strength and stiffness of 2 fixation treatments used to repair acute slipped capital femoral epiphysis were evaluated in bone specimens from immature dogs. A servohydraulic testing machine was used to create slipped capital femoral epiphysis in 7 pairs of femurs by shearing the capital femoral epiphysis along the physis in a craniocaudal direction. The slip was reduced and repaired with one 3.5-mm-diameter screw placed in lag fashion or 2 double-pointed, 1.6-mm (0.062 inch)-diameter smooth pins and retested. Strength and stiffness of each intact femur (which served as the control) and repaired femur were compared. Results of the study indicated that the failure strength of 2-pin fixation was significantly (P < 0.05) weaker than its control and the 1-screw fixation. There was no significant difference between failure strength of the 1-screw fixation and its control. The stiffness of 1-screw and 2-pin fixations was not significantly different, compared with each other, but was significantly (P < 0.05) less, compared with their respective controls.

Free access
in American Journal of Veterinary Research

Summary

The biomechanical strength and stiffness of 3 fixation techniques used to repair acute slipped capital femoral epiphysis were evaluated in bone specimens from immature dogs. A servohydraulic testing machine was used to create slipped capital femoral epiphysis in 9 pairs of femurs by shearing the capital femoral epiphysis along the physis in a craniocaudal direction. The slip was reduced and repaired with 1, 2, or 3 double-pointed, 1.6-mm (0.062-inch) smooth pin(s) and retested. The strength and stiffness of each intact femur (which served as the control) and repaired femur were compared. Results of the study indicated that differences among the failure strengths of 1- and 2-pin fixations and their respective controls were not significant; however, the 3-pin fixation was 29% stronger than its control and was 60 and 45% stronger than the 1- and 2-pin fixations, respectively. One- and 2-pin fixations were 34 and 24% less stiff than their respective controls, whereas the stiffness of the 3-pin fixation was similar to its control. The 2- and 3-pin fixations were 48 and 76% stiffer, respectfully, than the 1-pin fixation, but were not significantly different, compared with each other.

Free access
in American Journal of Veterinary Research

Abstract

Objective

To investigate the effect of recombinant canine somatotropin (STH) on the metabolic and histologic aspects of bone healing in dogs, using an unstable os-tectomy gap model.

Animals

8 mature dogs.

Procedure

A 3-mm ostectomy of the mid portion of the radius was performed in all dogs. Implants designed to release STH at a rate of 4 mg/d were placed SC in 4 dogs (treated group [STHG]), and another 4 dogs received no implants (control group ICG]). Serum concentrations of STH, insulin-like growth factor I, and osteocalcin were de-termined before surgery, and weekly for 8 weeks. Scinti-graphic evaluation of the ostectomy sites was performed before surgery, and at weeks 2, 4, 6, and 8 after surgery. Histologic evaluation of the ostectomy sites was performed at the conclusion of the study at week 8.

Results

Significant (P < 0.05) increases in serum STH, insulin-like growth factor I, and osteocalcin concentrations were observed in dogs of the STHG during the 8-week study period. Scintigraphic activity of the ostectomy sites was increased in dogs of both groups, but dogs of the STHG had significantly (P < 0.05) greater activity, compared with dogs of the CG. Coalescence of nuclear activity across the ostectomy site was observed in dogs of the STHG, whereas dogs of the CG maintained 2 distinct areas of metabolic activity. Histologically, dogs of the STHG had bridging calluses with areas of endochondral ossification and ongoing osteogenic activity, whereas dogs of the CG had nonossified fibrocartilage typical of nonunion fractures.

Conclusion

Using the ostectomy gap model, recombinant canine STH enhanced the metabolic and histologic aspects of bone healing in dogs. (Am J Vet Res 1996;57:1395–1401)

Free access
in American Journal of Veterinary Research