Is a Magnetic-Manual Targeting Device an Appealing Alternative for Distal Locking of Tibial Intramedullary Nails?

Lukas L Negrin,Vilmos Vécsei

doi:10.5812/atr.10638

Abstract

BackgroundIn order to enable a radiation-free, accurate and simple positioning of distal locking screws, a combined magnetic and manual targeting system has been developed by Sanatmetal®. Where a low-frequency magnetic field is initially used to detect the position of the first drill hole and three more holes can be found with a mechanical template.ObjectivesOur cadaver study was performed to evaluate the accuracy and efficiency of this device.Materials and MethodsIn two runs, 30 probands (group 1: 10 students; group 2: 10 residents; group 3: 10 attendings), none of who being familiar with the device, tested the radiation-free system using 60 intact cadaver tibias. Each proband performed the surgical procedure twice in succession.ResultsReferring to the first attempts, 9.6, 7.2 and 7.1 minutes were the time periods required to insert the four distal screws and the relevant values for the second attempts were 8.6, 6.3 and 6.2 minutes; in both cases revealing a significant difference between group 1 and 2 and group 1 and 3. Furthermore, the mean values within each group indicated a significant decrease of the test duration. Out of the 240 drillings, only one failure (group 1) occurred, representing an accuracy of 99.58 %. Of the probands, 90 % rated the targeting device better than the free-hand technique and 77 % at least attested a high user-friendliness.ConclusionsDue to our satisfactory test results, the brief training, the steep learning curve and the radiation-free technique the new device has to be considered an appealing alternative for distal locking.

Highlights

In order to enable a radiation-free, accurate and simple positioning of distal locking screws, a combined magnetic and manual targeting system has been developed by Sanatmetal®
We evaluated its accuracy and the time period that was necessary to place all of the four provided distal screws, starting with the montage of the distal targeting device onto the insertion guide. 30 probands, none of them familiar with the device at the time of investigation were subdivided into three equal groups
To our opinion, aiming devices for distal locking of intramedullary nails without the need of x-ray control have to be welcomed on principle

Summary

Introduction

In order to enable a radiation-free, accurate and simple positioning of distal locking screws, a combined magnetic and manual targeting system has been developed by Sanatmetal®. Even though a lead apron provides adequate protection to surgeon’s trunk and gonads [11], her/his hands are frequently directly exposed to the x-ray beam Per intramedullary nailing they receive a mean radiation dose of 0.330 mSv. Of interest, a value of 0.023 mSv is related to distal locking when performed by a consultant, whereas this value increases to 0.028 mSv for a middle-grade surgeon [9]. Due to the fact that distal locking is a challenging step during intramedullary nailing the free-hand technique can lead to a significant increase in radiation exposure. Krettek et al [12,13,14] analyzed implantation-induced nail deformation in unreamed tibial nails, detecting lateral translations in the range of 14.3 mm, dorsal translation in the range of 19.2 mm and rotational deformation around the longitudinal axis of the nail in the range of 2.4° Without compensation for this deformation, it is impossible to place the screws accurately. An innovative radiationindependent aiming device for distal locking of intramedullary nails was presented by Sanatmetal®(Hungary, Eger)

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Conclusion