Does Injection Site Matter? A Randomized Controlled Trial to Evaluate Different Entry Site Efficacy of Knee Intra-articular Injections.

Background: Complaints of knee pain secondary to early osteoarthritis may account for up to 30% of visits to primary care physicians. Due to the proposed inflammatory changes in early osteoarthritis, intra-articular injections of corticosteroids (IACS) have been considered as an option for disease progression modification, pain control, and improvement of function. However, some studies have suggested poor accuracy rates of IA injections depending on the entry site chosen. It is therefore the aim of this study to evaluate the efficacy of IA knee corticosteroid injection in reducing pain and improving function in patients with early osteoarthritis and whether the low accuracy rates reported with the Anterolateral joint line injection site translate to worse functional and pain outcome measures as compared to Suprapatellar lateral injections.

Materials and methods: The study was carried out as an open-label, randomized controlled trial with 60 sequential patients recruited. Simple randomization separated groups into anterolateral joint line or suprapatellar lateral injection sites. Improvements were measured with WOMAC and VAS scores after injection of Lidocaine and steroid solution.

Results: Patients receiving IACS injections had a measurable improvement in self-reported outcomes as evidenced by standard deviation change in WOMAC and VAS scores. The majority of patients had a clinically significant improvement in VAS scores as compared to their initial measures with a notable amount of patients improving significantly as well on their WOMAC scores, irrespective of the injection site chosen.

Conclusions: We have therefore continued the use of palpation-guided intra-articular knee injections in an effort to reduce costs as compared to other injection modalities with positive results in our osteoarthritis patients.