The Accurate Depth of Drilling the Saw Bone with K-wire, Drill Bit and Steinmann Pin

Abstract

Objectives: The purposes of this study were to determine the accuracy of free-hand technique in utilizing various instruments and whether using a protective device to prevent over-penetration of the instrument would reduce the chance of injury to the adjacent soft tissue structures.

Materials and Methods: Forty orthopaedic residents at Siriraj Hospital were enrolled in this study. A 3.2 mm. drill bit, a 2.0 mm. K-wire, and Steinmann pin no.5 were inserted into an artificial saw bone with a cordless electric driver and stopped when they felt that the instrument had penetrated through the far cortex. The distance from the tip of the instrument to the far cortex of the saw bone was measured. This procedure was repeated 3 times. Then, with the same group of orthopaedic residents, the width of the saw bone was measured radiographically. The actual width of the saw bone was reduced by 10% due to the radiographic magnification. A protective device was then used to prevent the instrument from over-penetrating into the saw bone by adjusting the length of the protective device from the tip of the instrument according to the x-ray measurement. This experiment was repeated 3 times, data were collected, and mean values were calculated. The results from the 2 groups were compared by using paired t-test.

Results: The mean distances for the 3.2 mm. drill bit, 2.0 mm. K-wire, and Steinmann pin no.5 were 8.06 mm. (2.33 mm.-17.37 mm.), 5.09 mm. (1.33 mm.- 11 mm.), and 4.9 mm. (0.67 mm.-12 mm.) respectively in the free-hand technique group, and 1.42 mm. (0.33 mm.-3.33 mm.), 1.53 mm. (0.33 mm.-2.67 mm.), and 1.44 mm. (0.33 mm.-3.0 mm.) respectively in the protective device group. The differences were statistically significant between the 2 groups (p <0.001). There were 10 times out of 360 times of drilling that the protective device touched the near cortex of the saw bone before the instrument penetrated through the far cortex.

Conclusions: Our study indicated that the over-penetrated distances were longer in the free-hand technique group than in the protective device group. We recommend the use of any kind of protective device which would reduce over-penetration to prevent injury to the surrounding soft tissue.