The Influence of Body Mass Index on Radiation Dose and Exposure Time in Fluoroscopic Guided Hip Injections - A Comparative Analysis of Two Approaches

Intra-articular hip injections (IHI) are routinely performed for both diagnostic and therapeutic purposes. The procedure can be performed via either an anterior or a lateral approach with fluoroscopic guidance being widely practised. There is a risk of radiation exposure associated with fluoroscopy assisted IHI. This may be influenced either by the surgical approach or the patient ’s body mass index (BMI) or both. This study was undertaken to compare the relationships of the respective approaches to BMI, fluoroscopic exposure time (FET) and radiation dose (RD).  A retrospective study was conducted comprising 74 patients who underwent IHI with 37 patients in each group (anterior and lateral). Patients were assessed pre -operatively and post operatively for any complications. The intra-operative radiation dose, fluoroscopic exposure time and BMI data were collected and analyzed.  The mean age of the patients in anterior and lateral groups was 61.18 ±14.08 and 67.21±14.39 years respectively. No complications were noted in either group. However, there was a significant increase in FET (P=0.002) and RD (P<0.001) in patients with BMI ≥ 30. In the lateral group, this trend was markedly noted with increase in FET (P<0.001) and RD (P<0.001) in patients with BMI ≥ 30. On the other hand, in the anterior group there was no statistically significant increase in FET (P=0.155) and only a moderate increase in RD (P=0.020) in patients with BMI ≥ 30.  Both anterior and lateral approaches to fluoroscopic guided IHI are equally safe in terms of complications involved. There is statistically significant increase in both radiation dose and fluoroscopic exposure time in patients with BMI ≥ 30. This is more pronounced in lateral approach. The anterior approach is most effective in reducing both radiation dose and fluoroscopic exposure time, more so in patients with BMI of 30 and above. Level of evidence: III