Background Viscosupplementation by intra-articular injections (IAI) of hyaluronic acid in the knee is widely used for symptom relief in patients with osteoarthritis of this joint. Previous studies have demonstrated that blind IAI are not always accurate in placing the needle in the knee joint space.
Objectives The aim of our study was to establish by ultrasonography the rate of correct, intra-articular delivery of the drug in patients with knee joint osteoarthritis, undergoing IAI of hyaluronic acid, and to individuate the main factors that could influence the IAI outcome
Methods All patients with knee osteoarthritis referred to our outpatient clinic for IAI were enrolled in the study. Demographic data of patients, Body Mass Index (BMI) and radiological grade of osteoarthritis were recorded. Injections were performed by two medical doctors, one with many years experience in IAI and the other with only a few months experience, in a random way (alternating one patient to each during the sessions). The access used for IAI was decided by the operator at the time of injection. A small air bubble was intentionally left in the syringe so that ultrasound could precisely identify the drug. Within 15 min of injection, patients were examined by ultrasound to define drug position (intra- or extra-articular). SPSS software was used for statistical analysis.
Results 42 patients (42 knees) were enrolled in the study (38 females). Air bubbles were easily recognized in all patients and exact drug position was readily identified. 24 IAI were performed by the expert operator. In 12 cases, lateral midpatellar access was used, while in the other cases anterolateral access was preferred. The drug was correctly positioned in 28 cases (67%). Logistic regression analysis demonstrated that the only variable influencing IAI outcome (among age, BMI, grade of osteoarthritis, operator experience, presence of intra-articular effusion) was operator experience.
Conclusions Two out of three IAI were correctly placed in the knee joint. Operator experience was the most important factor for correct intra-articular injection. BMI, effusion and the grade of osteoarthritis did not seem to influence the outcome of IAI. Correct training in IAI is therefore very important.
Jackson DW, Evans NA, Thomas BM. Accuracy of needle placement into the intra-articular space of the knee. J Bone Joint Surg Am. 2002 Sep;84-A(9):1522-7
Qvistgaard E, Kristoffersen H, Terslev L, Danneskiold-Samsøe B, Torp-Pedersen S, Bliddal H. Guidance by ultrasound of intra-articular injections in the knee and hip joints. Osteoarthritis Cartilage. 2001 Aug;9(6):512-7.
Disclosure of Interest None Declared