Intra-articular administration of medications has been shown to be highest with the injection performed lateral to the middle to proximal patella with the knee in extension. Extension allows greater patellar mobility and increases the available space in the patellofemoral joint compared to flexion. A lateral starting point when injecting into the patellofemoral joint has less overlying soft tissue than medial, which makes it easier to palpate the bony landmarks and evert the patella.
Jackson et al. evaluated 240 consecutive injections in patients without clinical knee effusion placed anteromedial, anterolateral, or lateral midpatellar. Using fluoroscopy to confirm location, accuracy rates were highest for the midlateral portal (93%) compared to anteromedial (75%) or anterolateral (71%).
Jackson DW, Evans NA, Thomas BM. Accuracy of needle placement into the intra-articular space of the knee. J Bone Joint Surg Am 2002; 84: 1522-1527.
PMID:12208907 (Link to Abstract)
Greene WB (ed): Essentials of Musculoskeletal Care, ed 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2001, pp. 371-372.