Imbibe - Surgical Technique - PSIS

BMA Surgical Technique
Posterior Iliac Crest Approach

Palpate the posterior superior iliac spine (PSIS) and the prominence of the posterior iliac crest. The entry point for the BMA needle into the posterior iliac crest must be no more than 8cm from the PSIS to avoid injury to the cluneal nerves. (Fig 6)

With a #11 or #15 scalpel, make a stab incision at the desired location over the iliac crest and place the sharp tip BMA needle (Fig 7) through the stab incision down to bone. Use the needle tip to "palpate" the iliac crest and, once the center of the crest is located, seat the needle tip into the cortical bone with one or two brisk taps with a small, lightweight mallet. Using a mallet to advance the needle through bone is the preferred technique as it affords the surgeon greater control of the needle. Advancing the needle by hand often requires excessive downward force and, should the needle suddenly lose contact with bone, may result in perforation of the sacrum or gluteal muscle.

Initially angle the BMA needle roughly 40 degrees lateral from the para-sagittal plane and 35-40 degrees caudad. Advance the needle approximately 0.5 to 1.0cm through the cortical bone by tapping with the small mallet. (Fig 8)

Exchange the sharp-tip trocar with the bullet-tip stylet (Fig 9). The bullet-tip stylet is designed to navigate between cortical bone boundaries as the rounded tip will deflect the needle back into cancellous bone and minimize risk of cortical perforation. (Fig 10)

Advance the needle to a depth of 2.0 to 2.5cm so that the aspiration holes are within bone. Remove the stylet and aspirate 2 to 4cc of marrow using a 10cc or 20cc syringe (a 20cc syringe provides greater vacuum for marrow aspiration). Detach the syringe from the needle and replace the bullet-tip stylet.

Advance the needle an additional 2.0 to 2.5cm along the same trajectory and again aspirate 2 to 4cc of marrow. Additional marrow may be obtained using a "fan" technique. Withdraw the needle enough so that it can be redirected 25° caphalad or caudad, then advance the needle to a minimum depth of 2.0 to 2.5cm before aspirating again. (Fig 11)