Which approach do you think is best? I've seen (and done) knees injected with the patient in different positions, with all different approaches.
To me it seems like having them sit down, and then using an inferior approach is most likely to land the solution in the right spot, because you are almost certain that you are in the joint space. But whenever I look at a knee model or an atlas, it looks like the important internal ligaments are right there also. How do you know you're not hitting them? Because I see people putting the needle quite deep into the knee. It's also easier to hit the cartilage.
Having them lie down and using a superior approach definitely seems a lot safer. The big quadriceps tendon is there, but not many other structures. OTOH, it seems less likely that you end up in the right space with this approach because the space is much smaller and the technique much less intuitive overall.
The best approach would obviously be with the use of Ultrasound guidance, however not many would do a knee injections using US.
If you would like an evidence-based answer take a look at the article below:
Jackson et al. Accuracy of Needle Placement into the Intra-Articular Space of the Knee. THE JOURNAL OF BONE & JOINT SURGERY. VOLUME 84-A. NUMBER 9. SEPTEMBER 2002
The cliff notes: The accuracy obtained with use of the lateral midpatellar
portal was significantly greater than that obtained with use
of either the anteromedial (p < 0.01) or anterolateral (p <
0.001) portal.
This article didn't really look at safety but only accuracy. Its a good read.
Accuracy of ultrasound-guided and palpation-guided knee injections by an experienced and less-experienced injector using a superolateral approach: a cadaveric study.
Heather M Curtiss, Jonathan T Finnoff, Evan Peck, John Hollman, Jeff Muir and Jay Smith PM R 3(6):507-15 (2011) PMID 21665162
During fellowship I learned the superolateral approach. You know you'r in the right place because you aspirate before injecting. You will appreciate synovial fluid in the syringe which is consistent w ia joint injection.
Re-read the US article above. All experienced providers were 100% in the joint. US might be good when you are learning, but useless once you are learned. I prefer fluoro with air contrast when I need to know I am in the joint. Some research protocols require fluoro with air contrast to prove the injection was IA. And once they bundle US in with all these injections......then guess what- poof.