Approach Considerations
Iliac crest biopsy can be performed via either a horizontal or a vertical approach. In the vertical approach, the specimen contains mostly trabecular bone, enabling assessment of subcortical and deep cancellous bone without size limitations. In the horizontal approach, the specimen contains trabecular bone in between two intact cortices, providing information on the outer and inner cortices; however, the sample size is restricted by the thickness of the iliac bone.
Normally, bone samples are considered adequately sized for qualitative and quantitative bone histology assessment if they are 0.4-0.5 cm in diameter, 2.5-3.5 cm in length obtained vertically, or 0.6-0.8 cm in diameter taken horizontally from the anterior iliac crest.
The biopsy can be performed using either a manual trocar or an electric drill. The electric drill is now widely used because it provides easier and shorter surgical time with a one-step drilling and extraction process. It also can be used with disposable drill bits to decrease infectious complications and avoid problems with dull drill bits.
Regardless of the instrument and technique used, the skill of the operator is a crucial part in obtaining an intact bone core that is not fractured or crushed.
Transiliac Bone Biopsy With Manual Trocar
Place the patient in the supine position, with the ilium and umbilicus exposed. Clean the anterior ilium with chlorhexidine or povidone-iodine solution, and drape. Locate the site of the biopsy (see the image below), which is 2 cm posterior to the anterior superior iliac spine (ASIS).
Biopsy site is identified 2 cm posterior to anterior iliac crest (dotted line outlines iliac crest). Image courtesy of Clin J Am Soc Nephrol 3:S164-S169, 2008.
Prepare 10-20 mL of 1% lidocaine to anesthetize the skin, subcutaneous tissue, and periosteum of the iliac crest. Infiltrate the skin and subcutaneous tissue using a 25-gauge needle, then administer lidocaine to the periosteum through a 1.5-in. (3.8-cm) 20-gauge needle while moving over the surface of the lateral ilium; cover an area of 1-2 cm (see the image below).
Lidocaine (10%) is used to anesthetize skin, subcutaneous tissue, and periosteum. Image courtesy of Clin J Am Soc Nephrol 3:S164-S169, 2008.
Make a 0.5- to 1.0-cm vertical skin incision at the previously selected biopsy site using a No. 11 blade with a scalpel. Separate the underlying muscle and fascia by blunt dissection until the lateral iliac periosteum is exposed (see the image below).
After incision is made, muscle and fascia are separated by blunt dissection until periosteum is exposed. Image courtesy of Clin J Am Soc Nephrol 3:S164-S169, 2008.
Fill the trephine biopsy needle with bone wax (using a 1- to 2-cm block of wax); this helps secure the bone specimen within the cutting trephine while it is being withdrawn.
Insert the pointed trocar through the outer guide sleeve, then introduce it through the skin incision. Advance the outer guide and pointed trocar firmly to the exposed bone, and point it toward the umbilicus. Rotate the outer guide until the teeth are resting firmly on and anchored to the lateral ilium surface to prevent slippage of the trephine biopsy needle while it is advanced through the sleeve during the biopsy (see the image below).
Pointed obturator, together with outer guide, is inserted and applied firmly to exposed bone. Guide is rotated and implanted on lateral ilium. Image courtesy of Clin J Am Soc Nephrol 3:S164-S169, 2008.
Withdraw the pointed trocar, then insert the trephine through the outer guide. An assistant should help, holding the contralateral hip down. Rotate the trephine clockwise, apply steady moderate pressure, increase pressure gradually until sensing the cutting action on the bone, and advance through the full depth of the iliac crest. Advancing the trephine with gentle and steady pressure is very important, especially in patients with fragile osteoporosis, in order to achieve an intact bone core (see the image below).
Trephine is inserted into outer guide and rotated counterclockwise with steady pressure until cutting action of trephine on bone is felt. Image courtesy of Clin J Am Soc Nephrol 3:S164-S169, 2008.
Advance the trephine until it penetrates the inner cortical bone. Rotate the trephine 360°, first clockwise and then counterclockwise. These steps should free the bone specimen from the connective tissue at the inner periosteal surface. Remove the trephine slowly by rotating counterclockwise. Remove the outer guide, and apply gauze over the incision site.
Insert the blunt extractor through the top of the trephine and gently push out the bone core specimen. Place the specimen in 10% phosphate-buffered formalin.
Close the incision with 3-0 nylon sutures. Apply antiseptic ointment. Cover the site with a small adhesive pad and elastic pressure dressing. The procedure should be completed in 15-20 minutes with minimal blood loss.
Transiliac Bone Biopsy With Electric Drill
The beginning of the procedure is the same for bone biopsy with an electric drill as it would be for biopsy with a manual trocar.
After the skin incision and blunt dissection of the subcutaneous tissue are performed, apply a funnel-shaped winged positioner at the incision site, and place it over the iliac crest surface. An assistant will help, holding the wing of the funnel. Align the axis along the underlying bone to prevent the trephine from departing from the pelvic bone during drilling.
Place the precutter on the drill in the center of the funnel, and engage the electric drill by pressing the first trigger or button.
Replace the precutter with the actual trephine, and then insert through the funnel. Drill with minimal pressure, and continue until the base of the drill just reaches the bottom of the funnel without touching it. To prevent heat artifacts on bone cells, avoid using high speed in drilling.
Pull the drill slowly upward. Use an internal plunger to expel the bone core from the trephine. Eject the core sample while pressing the second button on the drill. Plug the cavity created by the trephine with sterile medical wax.
Specimen handling, skin closure, and skin care are carried out in the same manner as for biopsy with a manual trocar.
Specimen Handling and Processing
Ensure that processing of the bone samples will be performed without decalcification, and have available an experienced pathologist who is able to interpret the data.
Either place the specimen in 70% ethanol immediately after the procedure, or place it in commercially prepared 10% phosphate-buffered formalin at room temperature for 24 hours and then transfer it into 70% ethanol at room temperature and send it to the laboratory.
Fixing duration should not be more than 48 hours, because tetracycline labeling can be washed out with prolonged fixation. Avoid using concentrated formalin, because it can leach out calcium, aluminum, and tetracycline from the bone.
After the specimen is fixed, dehydrate it in alcohol, embed it in methylmethacrylate, and later cut it with a special microtome. The sections are stained with either toluidine blue or Masson-Goldner trichrome.
The specimens can be analyzed for bone histomorphometric measurements by means of commercially available computer software applications.
Complications
Transiliac bone biopsy is generally well tolerated, with minimal pain and discomfort. It is associated with very little morbidity and no mortality. Complications are rare and mild and include the following [3, 6] :
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Pain
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Hematoma
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Transient neuropathy
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Skin incision site infection
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Exostosis [21]
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Allergic reactions, gastrointestinal disturbances, and photosensitivity secondary to tetracycline intake
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Tetracycline double-labeling on bone-osteoid surface as seen in fluorescent light. Image courtesy of Clin J Am Soc Nephrol 3:S164-S169, 2008.
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Electric drill for horizontal and vertical iliac crest biopsies. Image courtesy of Clin J Am Soc Nephrol 3:S164-S169, 2008.
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Modified Bordier trephine, from top to bottom, includes pointed trocar, outer guide or sleeve, trephine, and blunt extractor. Image courtesy of Clin J Am Soc Nephrol 3:S164-S169, 2008.
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Biopsy site is identified 2 cm posterior to anterior iliac crest (dotted line outlines iliac crest). Image courtesy of Clin J Am Soc Nephrol 3:S164-S169, 2008.
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Lidocaine (10%) is used to anesthetize skin, subcutaneous tissue, and periosteum. Image courtesy of Clin J Am Soc Nephrol 3:S164-S169, 2008.
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After incision is made, muscle and fascia are separated by blunt dissection until periosteum is exposed. Image courtesy of Clin J Am Soc Nephrol 3:S164-S169, 2008.
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Pointed obturator, together with outer guide, is inserted and applied firmly to exposed bone. Guide is rotated and implanted on lateral ilium. Image courtesy of Clin J Am Soc Nephrol 3:S164-S169, 2008.
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Trephine is inserted into outer guide and rotated counterclockwise with steady pressure until cutting action of trephine on bone is felt. Image courtesy of Clin J Am Soc Nephrol 3:S164-S169, 2008.
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Trephine advancing through full length of iliac crest. Image courtesy of Clin J Am Soc Nephrol 3:S164-S169, 2008.
