Impact of body habitus on fluoroscopic radiation emission during minimally invasive spine surgery

OBJECT Minimally invasive spine surgeries (MISSs) have gained immense popularity in the last few years. Concern about the radiation exposure has also been raised. The purpose of this study was to demonstrate the impact of body habitus on the radiation emission during various MISS procedures. The authors also aim to evaluate the effect the surgeon's experience has on the amount of radiation exposure during MISS especially with regard to patient size. METHODS The authors conducted a retrospective analysis of 332 patients who underwent 387 MISS procedures performed at their institution from January 2010 to August 2013 by a single surgeon. The dose of radiation emission available from the fluoroscopic equipment was recorded from the electronic database. The authors analyzed mainly 3 procedure groups: microdiscectomy/decompression (MiDD, n = 211) and transforaminal lumbar interbody fusion (TLIF) either with unilateral instrumentation (UnTLIF, n = 106) or bilateral instrumentation (BiTLIF, n = 70). The patients in each procedure group were divided into 6 categories based on the WHO criteria for obesity: underweight (body mass index [BMI] < 18.50), normal (18.50-24.99), overweight (25.00-29.99), Class 1 obese (30.00-34.99), Class 2 obese (35.00-39.99), and Class 3 obese (>40.00). RESULTS Patients who underwent BiTLIF had the highest median radiation exposure (113 mGy, SD 9.44), whereas microdiscectomy required minimal exposure (12.62 mGy, SD 2.75 mGy). There was a significant correlation between radiation emission and BMI of the patients during all MISS procedures (p < 0.05). The median radiation exposure was substantially greater with larger patients (p <= 0.001). In the analyses within the procedure groups, radiation exposure was found to be significantly high in patients who were severely obese (Class 2 and Class 3 obesity). The radiation emission was lower during the surgeries performed in 2013 than during those performed in 2010 especially in obese patients; however, this observation was not statistically significant. CONCLUSIONS Body habitus of the patients has a substantial impact on radiation emission during MISS. Severe obesity (BMI >= 35) is associated with a significantly greater risk of radiation exposure compared with other weight categories. Surgical experience seems to be associated with lower radiation emission especially in cases in which patients have a higher BMI; however, further studies should be performed to examine this effect.