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SUMMARY

The breaking strength (stress at failure) of equine third metacarpal bones, with and without clustered drill holes, was determined in vitro. Paired ossa metacarpalia II-IV of 39 horses (n = 39) between 2 and 7 years old were tested in palmarodorsal 3-point bending. Four treatments were compared. Clustered 2.7- or 3.5-mm drill holes, in a 4- or 7-hole pattern, were made in the dorsal cortex of the distal diaphysis of the left third metacarpal bone. Undrilled right third metacarpi were used as controls. Bones with clustered drill holes failed by an oblique fracture through 1 or more drill holes, whereas undrilled bones failed with a middiaphyseal transverse fracture. Clustered drill holes acted as a stress concentrator and significantly (P < 0.05) decreased the stress required for failure. However, differences in breaking strength between treatment groups were not significant (P > 0.05).

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in American Journal of Veterinary Research

the standard drill hole group, whereas the contralateral bone was assigned to the oversize hole group. All bones were continuously irrigated with physiologic saline solution during sawing, drilling, tapping, and screw insertion procedures. A bone saw

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in American Journal of Veterinary Research

lead, and point angles; flank; chisel edge and point; cutting face; flute geometry; web; land; and body, influence the mechanics of a drill hole through bone. 11 , 12 Drill bit sharpness and heat generation can also affect the efficiency of the drill

Open access
in American Journal of Veterinary Research

Abstract

Objective

To examine the amount of heat generated in equine cortical bone by a 6.2-mm drill, using low- and high-speed and controlled feed rate drilling.

Sample Population

10 metacarpal bones harvested from five 2-year-old draft-type horses.

Procedure

Drilling on metacarpal bones was done using a machine shop mill with which the feed rate and drill speed could be precisely controlled. Bones were drilled, using 6 combinations of feed rate (1, 2, and 3 mm advance/s) and drill speed (317 and 1,242 revolutions/min [rpm], with maximal temperatures recorded by thermocouples placed 1, 1.5, and 2 mm from the drill. Maximal temperatures were evaluated for the effect of feed rate, drill speed, cortical thickness, and distance from the drill, using linear regression analysis.

Results

Increasing feed rate from 1 to 2 and from 2 to 3 mm/s significantly decreased mean maximal temperature. Increasing drill speed from 317 to 1242 rpm significantly increased mean maximal temperature. Increasing cortical thickness significantly increased mean maximal temperature, and increasing the distance from the drill hole significantly decreased mean maximal temperatures.

Conclusions

On the basis of our results, we recommend using low drill speeds while applying sufficient axial force to advance the drill as rapidly as possible through the bone.

Clinical Relevance

Results of using this in vitro model suggest that temperatures at the drill-bone interface may be sufficiently high to result in significant thermal necrosis when drilling equine cortical bone. (Am J Vet Res 1999;60:942–944)

Free access
in American Journal of Veterinary Research

thermocouples placed 0.5 mm from the drill hole indicated mean peak temperatures of 40°, 56°, and 89°C in rabbit, canine, and human femoral cortical bone, respectively. 8 Higher temperatures in canine and human femora were attributed to greater cortical

Full access
in American Journal of Veterinary Research

self-tapping screws were inserted at the same angle as for the drilled holes. Data analysis —Descriptive analysis was performed by use of statistical software. g Minimum and maximum angles measured on preoperative images were recorded as mean ± SD

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in American Journal of Veterinary Research

distance between the ventral edge of the sacral wing and the median of the sacrum ( Figure 1 ). Figure 3— Photograph of the lateral aspect of the sacroiliac joint surface of the sacrum of a cat. The implant has been removed, and the exit drill hole (X

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in American Journal of Veterinary Research

sacroiliac luxation stabilization. The objective of this study was to evaluate the ease and accuracy of drilling holes through the ilium and into the sacral body using a generic 3-DP drill guide to facilitate fluoroscopic-assisted Kirschner wire placement

Open access
in American Journal of Veterinary Research

. Autogenous fascia lata was harvested and split longitudinally then the medial aspect of the graft was fed through a drill hole in the proximal tibia and fixed to the medial parapatellar fascia. The lateral aspect of the graft was fixed to the lateral

Full access
in Journal of the American Veterinary Medical Association

were created with a custom tap f designed for this purpose. The allogeneic bone screw was then inserted and tightened by hand. After removal of the metal screw used for temporary fixation, the second drill hole was then enlarged to a uniform diameter

Full access
in American Journal of Veterinary Research