Inverted C-arm Orientation During Simulated Hip Arthroscopic Surgery.

Background: Fluoroscopic guidance is routinely utilized during hip arthroscopic surgery. Previous studies have shown that the C-arm orientation can significantly affect radiation exposure for both the surgeon and the patient during orthopaedic procedures. However, this has not been previously assessed for hip arthroscopic surgery.

Hypothesis: Using an inverted C-arm during hip arthroscopic surgery will reduce radiation exposure to the patient and surgeon.

Study Design: Descriptive laboratory study.

Methods: A simulation study measured scatter radiation during hip arthroscopic surgery performed in the supine position under fluoroscopic guidance with an anthropomorphic pelvic phantom on a radiolucent operating table. Radiation exposure tested 2 different C-arm orientations: standard and inverted. Testing was performed at 6 locations corresponding to the patient, surgeon's neck, surgeon's waist, surgical technician, anesthesiologist, and radiology technician. Statistical analysis was performed using univariate and multivariate analyses assessing radiation exposure between the C-arm orientations. A risk calculation for carcinogenesis was performed based on reported radiation dosages.

Results: Radiation exposure (in mGy/min) was more than 100-fold higher for the patient compared with the surgeon in both C-arm orientations. The inverted C-arm orientation resulted in a 2.48-fold decrease in patient radiation exposure when compared with the standard orientation (10.8 mGy/min vs 26.8 mGy/min, respectively). There was a small but significant increase in surgeon radiation exposure in the inverted orientation compared with the standard orientation (0.072 vs 0.067 mGy/min, respectively). The patient's carcinogenesis risk was decreased 2.64-fold with the inverted orientation compared with the standard orientation (1.4 × 10-5 vs 3.7 × 10-5 , respectively).

Conclusion: The inverted C-arm orientation resulted in a 2.48-fold decrease in patient radiation exposure with a 2.64-fold decrease in the carcinogenesis risk compared with the standard orientation. Inadvertently, the inverted orientation provided a 9-cm increase in the surgeon's working area. Our data supported the clinical utilization of the inverted C-arm orientation during hip arthroscopic surgery to minimize patient radiation exposure. Although there was a minimal but significant increase in surgeon radiation exposure with the inverted orientation, we believe that this is negligible when incorporated with standard leaded protective equipment as contrasted with the significant dose reduction for the patient as well as the decreased risk of carcinogenesis and hereditary disorders.

Clinical Relevance: Patients undergoing hip arthroscopic surgery routinely acquire radiation exposure during the use of the C-arm. Measures to minimize radiation via the inverted C-arm orientation will decrease the unnecessary risk to the patient while continuing to allow for optimal treatment.