Novel Passive Two-Stage Magnetic Targeting Devices for Distal Locking of Interlocking Nails.

Tze-Hong Wong,Wensyang Hsu,Yuh-Shyong Yang,Meng-Shiue Lee,Sung-Yueh Wu,Chia-Pei Wu,Tien-Kan Chung,Pei-Jung Hsu

doi:10.1155/2017/3619403

Abstract

Interlocking nailing is a common surgical operation to stabilize fractures in long bones. One of the difficult parts of the surgery is how to locate the position and direction of a screw hole on the interlocking nail, which is invisible to the naked eye after insertion of the nail into the medullary canal. Here, we propose a novel two-stage targeting process using two passive magnetic devices to locate the position and direction of the screw hole without radiation for the locking screw procedure. This involves a ring-shape positioning magnet inside the nail to generate a magnetic field for targeting. From the accuracy test results of these two-stage targeting devices, the search region can be identified in less than 20 seconds by the 1st-stage targeting device, while the total targeting time to locate the drilling position and direction takes less than 4 minutes, with 100% successful rate in 50 attempts. The drilling test further combines the two-stage targeting process and drilling process on the swine tibia, and it is shown that a 100% successful rate is achieved in all 10 attempts, where the total time needed is less than 5 minutes.

Highlights

Interlocking nailing, known as intramedullary nailing, is a common surgical operation to stabilize fractures in long bones [1,2,3,4,5] and is one of the best methods for treating fractures of the lower extremities [6, 7]
The procedure involves the insertion of a hollow nail in the bone medullary canal, which is secured by screws at the proximal and distal ends to prevent the rotation or displacement of the bone after adequate reduction
By moving the guiding device around the positioning area identified by the 1st-stage targeting device, once three magnetic pins reach to symmetrical positions without contacting the conductive ring on the upper transparent baseboard, as shown in Figure 4(c), the green light-emitting diodes (LEDs) instead of red will be switched on

Summary

Introduction

Interlocking nailing, known as intramedullary nailing, is a common surgical operation to stabilize fractures in long bones [1,2,3,4,5] and is one of the best methods for treating fractures of the lower extremities [6, 7]. To avoid using X-rays, which are harmful to humans, transilluminating [13], sound-guided [10], ultrasonic [14], and magnetic [15, 16] methods were proposed to find the drilling position. These methods were unable to locate the exact drilling direction. A novel two-stage magnetic targeting process with two passive targeting devices is proposed to provide a rapid and accurate method for the distal locking of interlocking nailing without radiation. A light-based indicator is integrated with the 2nd-stage targeting device to indicate the alignment state during the targeting process in a more intuitive way

Concept Design

Detail Design

Fabrication

Testing Results and Discussion

Conclusions

Conflicts of Interest