Commentary on
"Radiation Exposure with Use of the Inverted C-Arm Technique in Upper Extremity Surgery"
By Michael R. Tremains, MD et al.

Commentary by Thomas J. Graham, MD*,
The Curtis National Hand Center, Union Memorial Hospital,
Baltimore, MD

The authors have described an adaptation of an imaging technique and provided correlative data concerning radiation exposure when the technique is employed. Although intraoperative image intensification has facilitated shortened operative times, the use of radiation-emitting devices in close proximity to the surgeon and the patient introduces potential radiation exposure, which is cumulative in the surgeon's case.

The results indicated both technical and (radiation) safety benefits when the inverted c-arm technique was employed. The amount of radiation exposure was significantly less with this technique (p < 0.001). Tremains et al. describe some of the potential "disastrous results" that may occur from "drilling through the image intensifier." Additional discussion about the effects of "scatter" and "leakage" from the tube, which are taken into account, further educates the reader about radiation safety.

The authors freely admit that this is not a new technique. It has been described in the literature and is employed widely by our colleagues in pediatric orthopaedics when pinning supracondylar fractures of the distal humerus^1,2. In that application, the dorsal brachium rests on the tube and the elbow is flexed over the collector; pins are introduced essentially parallel to the face of the tube or even at a slightly divergent angle.

What was not discussed in the article is the advent and widespread use of the "mini c-arm" in fluoroscopy technology which has significantly reduced radiation and provided benefits due to maneuverability of the device by the surgeon³. The data on radiation levels can be found in the radiology literature⁴, or in ancillary materials from the manufacturers. I believe that the mini c-arm units are important adjuncts to our practice in the operating room, the emergency room, and the clinic. They provide both the needed images and the margin of safety that we require.

I would caution against the routine use of the inverted c-arm technique in the elective surgical setting, however. A hand-table is more stable and provides a greater working area than does the cylindrical tube. The image intensifier is on a mobile (although supposedly locked) arm, which in turn is connected to a wheeled unit. Just the act of applying downward pressure to the hand-forearm unit on the tube causes motion and potential stress at the locked sites of the machine.

It is perfectly acceptable to have the image intensifier with the c-arm in its "inverted" position parked adjacent to the hand-table for the quick fluoroscopy shots needed throughout a procedure. This position is probably even safer with regard to radiation exposure for both the patient and the surgeon. Equally acceptable is a "horizontal" positioning of the source and a collector that can be wheeled in when needed. This latter positioning of the mini c-arm unit is my preference in the operating room. There is no direct stress or potential impaling of the unit, yet there is no hindrance to image gathering.

I recognize that not all practices or hospitals may be able to afford the new mini c-arm units. However, as surgeons further evaluate the costs and benefits of OR efficiency, ease of operation, and reduction of radiation exposure, I believe that utilization of the larger c-arm units in surgery of the distal upper-extremity will wane. The use of these units is simply too labor-intensive, cumbersome, and potentially dangerous. We all accept the risks of radiation exposure over the course of a career, but the potential of a single "catastrophe" resulting from metallic (pin or drill) perforation of the fluoroscopy unit is unacceptable.

I commend the authors on their study design and honest reporting. They remind us of a technique that may have application in the trauma setting when resources and space are compromised. I would not recommend the technique for "everyday" elective use because positioning the unit close to the operative field and employing it on an as-needed basis would yield the same results with a lesser risk of potential problems.

*The author did not receive grants or outside funding in support of his research or preparation of this manuscript. He did not receive payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, educational institution, or other charitable or nonprofit organization with which the author is affiliated or associated.

References

1. Kasser JR. Percutaneous pinning of supracondylar fractures of the humerus. Instr Course Lect. 1992;41:385-90.
2. Otsuka NY, Kasser JR. Supracondylar fractures of the humerus in children. J Am Acad Orthop Surg. 1997;5:19-26.
3. Hanel DP, Robson DB. The image intensifier as an operating table. J Hand Surg [Am]. 1987;12:322-3.
4. Arnstein PM, Richards AM, Putney R. The risk from radiation exposure during operative X-ray screening in hand surgery. J Hand Surg [Br]. 1994;19:393-6.