Ultrasound and anatomical study of accessing the nerves in the knee by fascial planes

The fascia is an undifferentiated mesenchymaltissue related to the peripheral nerves. Both can be identifiedby ultrasound, which is useful when performing peripheralnerve blocks. However, there is no unanimity about theapproaching point of each nerve, nor is there a consensus onhow to name the appropriate infiltration zone, although theparaneural zone is frequently mentioned. The aims of thisstudy were to determine if ultrasound is accurate foridentifying the fascial planes and the paraneural space ofthe nerves in the knee, infiltrating them, and achieving acorrect anatomical diffusion, as well as for establishing accessroutes to avoid intraneural infiltration. The study wasperformed in 16 cryopreserved lower extremities of thedissection room of the Faculty of Medicine and HealthSciences, University of Barcelona. Nerves of the knee were injected with colorant guided by ultrasound after they werevisualized. Correct location of the nerves by ultrasound wasachieved in 98.75% of the cases, correct visualization of theneedle by ultrasound in 82.5%, the hypoechogenic imagearound the nerve after infiltration in 82.5%, and a correctparaneural infiltration in 76.25% of cases. With these results,we can conclude that high-definition ultrasound enableslocation of the peripheral nerves and adjacent structures aswell as the fasciae that surround them, and therefore allowsperformance of infiltrations in the paraneural spaces