Is ultrasound-guided hip aspiration more successful than fluoroscopic-guided aspiration in diagnosing prosthetic joint infection?

Abstract

Introduction: aspiration of total hip arthroplasty (THA) is commonly performed to assist in the diagnosis of prosthetic joint infection (PJI). This study aimed to determine whether fluoroscopic- or ultrasound- guided hip aspiration differs in the ability to acquire synovial fluid and in the accuracy of diagnosing infection. Methods: all THA aspirations performed between 2014 and 2021 at our institution were retrospectively identified. Aspirations were classified as successful or dry. If successful, the volume of fluid obtained was recorded. The sensitivity and specificity of hip aspiration in identifying PJI were calculated with four methods: (1) culture results excluding saline lavage, (2) culture results including saline lavage, (3) 2018 Musculoskeletal Infection Society (MSIS) International Consensus Meeting (ICM) criteria, and (4) 2021 European Bone and Joint Infection Society (EBJIS) criteria. Analyses were performed using Student's $t$ test or Wilcoxon rank sum for continuous variables and chi-squared or Fisher's exact test for categorical variables. Results: 290 aspirations were included (155 fluoroscopic-guided and 135 ultrasound-guided). Success of aspiration ($>0.5$ mL) was more common in the ultrasound cohort (69 %) than fluoroscopy (53 %) ($p<0.0055$). When successful, more volume was obtained in the ultrasound cohort (mean 13.1 mL vs. 10.0 mL; $p=0.0002$). Ultrasound-guided aspiration was more sensitive than fluoroscopy in diagnosing PJI using culture results excluding saline lavage (85 % vs. 73 %; $p=0.03$), culture results including saline lavage (85 % vs. 69 %; $p=0.001$), 2018 MSIS-ICM criteria (77 % vs. 52 %; $p=0.02$), and 2021 EBJIS criteria (87 % vs. 65 %; $p=0.02$). Ultrasound-guided aspiration was more specific than fluoroscopy in diagnosing PJI using 2021 EBJIS criteria (100 % vs. 96 %; $p=0.001$). Conclusions: ultrasound-guided aspiration is more frequently successful and yields more fluid than fluoroscopic-guided aspiration of THA. Ultrasound-guided aspiration is more sensitive in diagnosing PJI than fluoroscopy using culture data, 2018 MSIS-ICM criteria, and 2021 EBJIS criteria.

Figure 1

Flowchart of aspirations included in this study.

Figure 2

Histogram of fluid distributions of each cohort.