Objective: The aim of this study was to determine whether the medial or the lateral mid-patellar approach is the most reliable for intra-articular knee injections.
Methods: The study included 76 knees of 76 patients divided into 2 groups. The first group consisted of 38 patients with a knee injury and resultant knee effusion. The second group included 38 patients without any known knee pathology. Patients were matched according to age and gender. The medial joint opening (medial patellofemoral angle) was calculated on a T1-weighted transverse image by measuring the anatomic angle between the femur and the patella. The lateral joint opening (lateral patellofemoral angle) was calculated in a similar way.
Results: The medial patellofemoral angle was significantly higher than the lateral patellofemoral angle in both groups (p<0.001).
Conclusion: The medial patellofemoral angle is significantly higher than the lateral patellofemoral angle in both healthy knees and knees with effusion. Therefore, the medial approach appears to be more accurate for intra-articular knee injection due to the medial joint's larger opening.