Accuracy of ultrasound-guided knee injections confirmed by fluoroscopy.

BACKGROUND

Injection with viscosupplements is a common treatment for knee osteoarthritis. However, there is a lack of knowledge about how the injectate spreads within the knee following an injection.

OBJECTIVE

Using ultrasound and fluoroscopy, this study seeks to assess whether injectate introduced into the suprapatellar recess disperses into the tibiofemoral joint.

DESIGN

Descriptive case series and reliability test-retest study.

SETTING

Outpatient rehabilitation center at an academic teaching hospital.

PATIENTS

14 adults between 44 and 80 with knee osteoarthritis, defined as a grade 2-4 on the Kellgren and Lawrence scale, who were candidates for hyaluronic acid injections.

INTERVENTIONS

Participants received ultrasound guided knee injections into the suprapatellar recess with hyaluronic acid and contrast. Post-injection fluoroscopic images were taken. The participants then underwent a walking protocol. Post-walking fluoroscopic images were then taken.

MAIN OUTCOME MEASUREMENTS

Determining if an injectate introduced into suprapatellar recess localizes to the tibiofemoral joint following a walking test; and assessing interrater agreement with between 2 radiologists and 1 interventional physiatrist with regards to location of injectate.

RESULTS

Injectate placed in the suprapatellar recess using ultrasound-guided technique will disperse to a varying extent from the suprapatellar recess into the tibiofemoral or patellofemoral joint after a brief bout of walking. Images of US-guided knee injections identified by an experienced interventionalist to represent correct needle placement and injectate location, confirmed by reference-standard fluoroscopy, can be corroborated by a blinded radiologist and are therefore reliable.

CONCLUSIONS

Fluoroscopic imaging confirmed that ultrasound-guided injection of hyaluronic acid into the suprapatellar recess dispersed into the tibiofemoral joint after a walking test. Future studies should examine whether the amount of injectate found in the tibiofemoral joint is correlated with patient outcomes.

LEVEL OF EVIDENCE

Level IV.