Guidance by ultrasound of intra-articular injections in the knee and hip joints.

OBJECTIVE: To develop and assess a stable method for ascertaining the placement of intraarticular injections for osteoarthritis (OA) in the hip and knee.

METHODS: Injections into the hip or knee joint with e.g. hyaluronan or cortisone were performed under the guidance of ultrasound. For this purpose an Acuson Sequoia apparatus and a 8-15 MHz transducer were used. After perforation of the capsule with a 21 G needle, 0.5-1 ml of atmospheric air and 1 ml lidocain 1% was injected with simultaneous recording of the ultrasound signals. This procedure was undertaken before the injection of the medication through the in situ needle.

RESULTS: In the hip joint the injected air could readily ascertain the placement of the injection with a sharp echoic contrast forming on the ultrasound picture respecting the joint cavity. In the knee joint the procedure gave the best results in joints which have a small amount of fluid in either the suprapatellar bursa or in a pouch regularly observed over the lateral joint margin. However, also in some so-called 'dry' knee joints the air could be traced in the bursa by ultrasound.

CONCLUSION: By the injection of air, it is possible to test the placement of intraarticular injections in both hip and knee joints. This procedure will give a supplementary documentation of the injection as compared to a mere ultrasonographic demonstration of the position of the needle in the joint. The method is proposed as a tool for both learning purposes and quality assurance in daily therapy.