Objective: To assess the accuracy rates of needle placements into the intra-articular space of knee OA.

Material and Method: This was a prospective study. Twenty-two patients with knee OA at Rajavithi Hospital received needle placement into intra-articular spaces using the three approaches, anteromedial (AM), anterolateral (AL), and lying lateral mid patella (LMP). The accuracy rates were confirmed by arthroscopy. Before and after injection of intra-articular hyaluronic acid at week 2, the visual analogue scale (VAS) was used to assess pain and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score was used in the evaluation of knee OA. The quality of life (QoL) was measured using the generic instrument Short Form-36 (SF-36).

Results: The majority of the participants were female. Their mean age was 58.41±5.82 years old, and their mean (±SD) BMI was 25.07±2.47 kg/m2. Their VAS and WOMAC scores improved significantly after injection compared to the baseline (p<0.001), but no significant differences in their QoL (SF-36) were observed after injection. The accuracy rate of intra-articular needle placement was highest (77.3%) using the LMP, followed by AL (63.6%) and lowest in the AM portal (31.8%). No significant difference was found between the accuracy rates of any of the needle placement groups based on KeL grade II. As for KeL stage III, the only significant difference between the accuracy rates was between those of the AM and the LMP approaches (23.1 vs. 76.9 accuracy rates, p = 0.006).

Conclusion: The LMP approach had the highest accuracy rate and is recommended for the treatment of patients with mild to moderate knee OA.

Keywords: Intra-articular, Knee osteoarthritis, Anteromedial, Anterolateral, Lying lateral mid patella