The objective of this study was to examine the accuracy of ultrasound-guided intra-articular (IA) injections on three different sites of the knee using midmedial, midlateral, and superolateral portals.
Ultrasound-guided IA injection and a radiographic evaluation were performed on 120 knees with osteoarthritis. Five milliliters of a mixed material consisting of 1% lidocaine (1 ml), 20 mg of triamcinolone (1 ml), and nonionic contrast (3 ml) was injected into the IA space of the knee through three different portals. After each injection, a radiographic evaluation was performed to determine whether the injected material had reached the IA space or infiltrated into the soft tissue.
Of 40 injections administered through the midmedial portal, 38 were confirmed as having been placed in the IA space on the first attempt (95% accuracy rate). Thirty-nine of 40 injections administered through the midlateral portal were IA on the first attempt (98.5% accuracy rate), as were 40 of 40 injections administered through a superolateral portal (100% accuracy rate). No significant differences (P > 0.05) were observed in the accuracy rate obtained with placement through the midmedial, midlateral, and superolateral portals.
All three ultrasound-guided IA injections may be used to access the knee joint, with a high rate of accuracy.