Fluoroscopically Guided Lateral Approach Hip Injection

Radiation Exposures

As our analysis demonstrates, mean radiation dose exposure for each group was consistent with low (≤ 3 mSv) to moderate (> 3-20 mSv) annual effective doses in the general population.⁷ Both anterior and lateral median radiation dose of 1 mGy and 3 mGy, respectively, are within the standard exposure for radiographs of the pelvis (1.31 mGy).⁹ It is therefore reasonable to consider a lateral approach for hip injection, given the benefits of direct coaxial approach and avoiding needle entry through higher bacteria-concentrated skin.

The lateral approach did have increased radiation dose and exposure time, although it was not statistically significantly greater than the anterior approach. The difference between radiation dose and time to perform either technique was not clinically significant. One potential explanation for this is that the lateral technique has increased tissue to penetrate, which can be reduced with collimation and other fluoroscopic image adjustments. Additionally, as trainees progress in competency, fewer images should need to be obtained.⁷ We hypothesize that as familiarity and comfort with this technique increase, the number of images necessary for successful injection would decrease, leading to decreased radiation dose and exposure time. We would expect that in the hands of a board-certified interventionalist, radiation dose and exposure time would be significantly decreased as compared to our current dataset, and this is an area of planned further study. With our existing dataset, the majority of procedures were performed with trainees, with inadequate information documented for comparison of dose over time and procedural experience under individual physicians.

Notable strengths of this study are the direct comparison of the anterior approach when compared to the lateral approach with regard to radiation dose and exposure time, which we have not seen described in the literature. A detailed description of the technique may result in increased utilization by other providers. Data were collected from multiple providers, as board-certified pain physicians and board-eligible interventional pain fellows performed the procedures. This variability in providers increases the generalizability of the findings, with a variety of providers, disciplines, years of experiences, and type of training represented.

Limitations

Limitations include the retrospective nature of the study and the relatively small sample size. However, even with this limitation, it is notable that no statistically significant differences were observed in mean radiation dose or fluoroscopy exposure time, making the lateral approach, at minimum, a noninferior technique. Combined with the improved safety profile, this technique is a viable alternative to the traditional anterior-oblique approach. Further study should be performed, such as a prospective, randomized control trial investigating the 2 techniques and following pain scores and functional ability after the procedure.

Conclusion

Given the decreased procedural risk related to proximity of neurovascular structures and coaxial technique for needle advancement, lateral approach for hip injection should be considered by those in any discipline performing fluoroscopically guided procedures. Lateral technique may be particularly useful in technically challenging cases and when skin entry at the anterior groin is suboptimal, as a noninferior alternative to traditional anterior method.