Using the operative hip rather than the contralateral hip as a radiographic reference may reduce fluoroscopy use relative to operative duration during direct anterior approach total hip arthroplasty, although the 2 techniques had similar absolute fluoroscopy times and radiation doses.
Researchers retrospectively reviewed 159 primary cementless direct anterior approach total hip arthroplasty (DAA-THA) procedures performed by a single orthopedic surgeon at 1 institution between January 2016 and May 2023. The analysis included adult patients undergoing primary THA for osteoarthritis with available intraoperative fluoroscopic images and radiation exposure reports. The contralateral hip group served as the radiographic reference in 77 procedures, and the ipsilateral, or operative, hip group served as the reference in 82 procedures. Mean age was 63 years and 64 years for each group , respectively, and mean body mass index (BMI) was approximately 31 kg/m² in both groups.
The researchers compared fluoroscopy time, radiation dose, and operative time between the 2 radiographic overlay techniques. They also normalized fluoroscopy time and radiation exposure to operative duration, which was used as a surrogate for case complexity, and evaluated the relationship between BMI and radiation use during DAA-THA.
Absolute fluoroscopy use was similar between the techniques. Mean fluoroscopy time was 60.4 seconds with the contralateral technique and 55.9 seconds with the ipsilateral technique, while mean radiation dose was 15.4 mGy and 13.0 mGy, respectively. Neither difference was statistically significant. There was a statistically significant difference in mean operative time, which was longer with the ipsilateral technique, at 164.6 minutes compared with 154.3 minutes with the contralateral technique.
When fluoroscopy measures were normalized to operative duration, however, the ipsilateral technique was associated with lower fluoroscopy use. Mean normalized fluoroscopy time was 0.34 arbitrary units with the ipsilateral technique compared with 0.39 arbitrary units with the contralateral technique, while normalized radiation dose was 0.08 vs 0.10 arbitrary units. Both differences were statistically significant.
BMI analyses provided additional context. When the researchers stratified patients by BMI, they found statistically significant effects of BMI and reference technique on radiation dose and operative time but not fluoroscopy time. A statistically significant interaction between BMI and reference technique was also observed for radiation dose. Across the cohort, BMI was moderately positively correlated with radiation dose and operative duration, whereas the relationship between BMI and fluoroscopy time was weak.
The researchers noted that greater radiation exposure with increasing BMI may occur without substantial increases in fluoroscopy duration because image intensifiers automatically increase exposure to maintain image quality in patients with higher BMI. However, limited numbers following BMI stratification prevented reliable post hoc comparisons of the interaction between BMI and reference technique.
Several limitations temper the findings. The study was retrospective and nonrandomized, involved procedures performed by a single surgeon, and may have been affected by learning-curve bias because the ipsilateral technique was predominantly used later in the study period. Image intensifier settings were not standardized retrospectively, and operative time was an imperfect surrogate for case complexity. The researchers also did not assess final clinical or radiographic outcomes, including limb-length discrepancy and restoration of femoral offset, and the limited sample size following BMI stratification reduced statistical power for further comparisons.
Both radiographic reference techniques resulted in comparable absolute fluoroscopy use during DAA-THA, while the ipsilateral technique may require less fluoroscopy relative to operative duration. Whether this difference can be achieved while maintaining equivalent limb-length and femoral-offset restoration remains uncertain. The researchers cautioned that the absolute reductions were modest, their clinical impact remained uncertain, and the retrospective findings should be considered hypothesis-generating pending further study.
“Ultimately, ongoing critical evaluation of fluoroscopic workflows remains imperative to lowering radiation exposure to patients and surgical teams without compromising surgical safety,” wrote lead study author Shivam H. Patel, of Orthopaedic Surgery at Sanford Health in Fargo, and colleagues.
The authors reported no financial support or conflicts of interest.
Source: Cureus
