Abstract
The insertion of Schanz screws into the bone during external-fixation procedures in trauma and elective orthopaedic surgery is usually done under röentgenologic control. In order to minimize irradiation exposure for the patients, as well as surgeons, we describe a simple method of Schanz screw placement. The röentgenologic control of the position of the half-pins is only necessary at the beginning and the end of the procedure. This technique is simple, shortens the operating time and reduces the amount of radiation exposure to both the patient and surgeon. It is a valuable technique in many resource-poor environments who do not have the facilities for an image intensifier fluoroscopy or C-arm as well as in austere situations such as during military operations.
Introduction
Current external fixators, as well as unilateral configurations and circular frames, normally use Steimann pins or Schanz screws, which are inserted through the bone by a closed method. The process of the insertion of the half-pins includes drilling, the determination of the correct depth and the insertion of properly measured Schanz screws. 1 These procedures require a certain amount of time and röentgenological control for the measurement of the optimal placement of the Schanz screws into the bone. An incomplete insertion to the far cortex may considerably reduce both the mechanical stability of the screw in the bone and the general rigidity of the external fixator. On the other hand, inserting the screw too deeply may result in serious consequences caused by the trauma to the soft tissues and possible damage to the neuro-vascular structures. 1,2 The extensive röentgenologic control increases the radiation load, for both patient and the operating team, and also increases the operating time. 3 In many resource-poor environments there is no facility for the fluoroscopic control of the insertion of half pins during external fixation procedures. Therefore, it was necessary to devise a simple, yet accurate, method for the placement of the screws.
Methods
We describe an easy method for the insertion of Schanz screws into a bone. The method decreases the need for prolonged röentgenological control and avoids unnecessary radiation exposure during the surgical procedure.
The limb is prepared and draped in the usual manner. The safe corridor is selected and a stab incision is made and deepened to the bone with a haemostat. The bone is then drilled and the passage of the drill through the far cortex of the bone is usually distinctly felt by the surgeon's hand. At this point, the drilling is stopped and a rubber cork is inserted onto the drill at skin level (as a marker). After the drill has been withdrawn from the bone, another rubber cork is placed on the prepared Schanz screw at the same level (Figure 1). The Schanz screw is then manually inserted into the bone until the cork reaches the skin.
The placement of a rubber cork on a Schanz screw in order to measure the required depth of insertion
Using this simple technique, instead of repeated fluoroscopic searches for each half-pin only one comprehensive röntgenological survey is necessary for the detection of any required minimal correction, which may then be performed after the insertion of all the half-pins.
Discussion
This technique has been successfully used for the treatment of dozens of trauma and orthopaedic patients at our centre with no complications to date. While it does not replace the usual roengenographic confirmation of the accurate placement of the screws at the end of the procedure, it considerably minimizes the exposure of theatre personnel and patients to radiation and shortens the operating time. It is also very useful in resource-poor environments and in austere conditions, such as during military operations or mass casualty situations, where there are no facilities for image intensifier fluoroscopy. 4