Comparison of knee arthrocentesis first-attempt success between Ultrasound-Guided, Ultrasound-Localised and Landmark-Guided techniques in the novice: A crossover study with random order of events

Introduction/Purpose

To compare knee arthrocentesis first-attempt success using landmark-guided, ultrasound-localised and ultrasound-guided techniques when performed by third-year medical students.

Methods

In this prospective, crossover study with randomised order of events, medical students performed three different arthrocentesis techniques on knee models: landmark-guided, ultrasound-localised and ultrasound-guided. Each subject attempted the techniques in a randomly assigned permutation at both high- and low-volume simulated knee effusions. The data were analysed with general estimating equations, which produced odds ratios comparing first-attempt success between different techniques at all effusion volumes.

Results

Ninety four of 111 third-year medical students were enrolled. Proportions of first-attempt success for the landmark-guided, US-localised and US-guided were 72%, 86% and 75%, respectively. For all effusion volumes, US-localised demonstrated a statistically significant increase in first-attempt success over the landmark-guided technique, OR = 2.38 (95% CI: 1.52–3.70). There was a greater increase in first-attempt success at low-volume effusions, OR = 2.86 (95% CI: 1.47–5.56), but no significant increase at high-volume effusions: OR = 1.85 (95% CI: 1.00–3.45). For all effusion volumes, US-guided demonstrated no difference to first-attempt success compared with landmark, OR = 1.15 (95% CI: 0.71–1.85). At low-volume effusions, US-guided demonstrated a statistically significant increase in first-attempt success over landmark-guided, OR = 2.17 (95% CI: 1.10–4.35), with no significant difference at high volumes, OR: 0.55 (95% CI: 0.28–1.06).

Discussion

The data presented here suggest that in this simulated knee model of arthrocentesis, ultrasound-guided approaches tend to have best efficacy at lower volume effusions, while ultrasound localized tends to do best at higher volume effusions, and both tended to perform better than the landmark technique. This study specifically looked at novices to both arthrocentesis and ultrasound, so extrapolating these results to other groups would require more study, but suggests that ultrasound incorporation into arthrocentesis benefits may offer some benefits for success rates and first attempt success.

Conclusion

In simulated knee arthrocentesis, ultrasound-guided techniques increased first-attempt success over landmark-guided techniques among medical students. This increase was most evident for arthrocentesis of smaller volume effusions.