Accuracy of needle placement into the intra-articular space of the knee in osteoarthritis patients for viscosupplementation

Introduction: Knee osteoarthritis is characterized by inflammation in the intra-articular space or synovial membrane, breakdown of articular cartilage, and sclerosis of the subchondral bone. Intra-articular injections of Sodium hyaluronate which have viscoelastic and protective effect on articular cartilage and restores normal articular homeostasis.The efficacy of these injections is diminished when they are placed inadvertently outside the joint. For the maximum benefit, injection of hyaluronic acid derivatives needs to be placed accurately into the knee joint. Aim: The study was performed to know the correct placement of needle inside the knee joint prior to Viscosupplementation by fluoroscopy using a contrast material. Materials and Methods: The accurate placement of needle was evaluated in a prospective series of 94 consecutive injections in patients without clinical knee effusion. All the injections were performed by single orthopaedic surgeon using a 5 cm 21-gauge needle through anterolateral, and lateral midpatellar portals. The needle placement in the knee joint was confirmed with fluoroscopy using the contrast material. Results: The accuracy rates through Lateral midpatellar and Anterolateral portals were lower than expected rate (100%). A total of 43 out of 47 injections were intra-articular, indicating accuracy of 91.5% through lateral midpatellar portal, 41 out of 47 injections were intra-articular through anterolateral portal with accuracy of 87.4%. Conclusion: Study showed that the accuracy of needle placement was higher through Lateral midpatellar than the Anterolateral portal.