Stifle joint block sites, horse

Stifle joint block sites in a horse. Although the medial femorotibial and femoropatellar joints generally communicate, all three compartments should be blocked separately to ensure complete desensitization of the stifle. 1. Medial femorotibial joint: A 21‑gauge, 3.8‑cm (1½‑inch) needle is inserted to its hub, if possible, perpendicular to the skin surface, in the space between the medial patellar ligament and the medial collateral ligament, proximal to the tibial plateau. The space is sometimes palpable as a depression, or as a bubble if joint effusion is present. 2. Femoropatellar joint: The joint can be accessed by either of two common approaches, both using a 21‑gauge, 3.8‑cm (1½‑inch) needle. The first approach is to insert the needle in the direction of the arrow, aiming beneath the patella in the trochlear groove. The second approach is to insert the needle perpendicular to the skin, at the point marked with the number 2 inside a circle. The needle contacts the lateral surface of the femur approximately 2 cm caudal to the palpable lateral trochlear ridge. The needle should be retracted slightly from the bone to either inject anesthetic or obtain synovial fluid. 3. Lateral femorotibial joint: A 21‑gauge, 3.8‑cm (1½‑inch) needle is inserted to its hub, if possible, perpendicular to the skin surface, lateral to the lateral patellar ligament, and proximal to the tibial plateau.