Bone Biopsy

Bone biopsy has been used as an invasive diagnostic procedure and a significant research method in the field of osteoporosis and other metabolic bone disease.[1] Several data can be obtained from bone histology, such as rate of bone resorption and remodeling, degree of bone mineralization, and bone structure.[2]

The iliac crest has been the preferred site for bone biopsy because it is easily accessible, is associated with fewer complications, and does not require extensive surgery.[3]

Transiliac bone biopsy is indicated for selected patients with metabolic bone disease who have an unusual clinical presentation when less invasive investigations have yielded inconclusive results.[4] Bone biopsy is rarely performed to diagnose patients with osteoporosis, for the following reasons[5] :

• Invasiveness of the procedure
• Lack of technical training among clinicians
• Pain
• Cost
• Requirement for specialized centers to interpret bone specimens
• Limited understanding of histologic results
• Availability of noninvasive diagnostic procedures that help establish the diagnosis

However, current biochemical markers are poor predictors of bone turnover, volume, and mineralization. Bone mineral density (BMD) measurement can only provide information about bone mineral content, which can be affected by a change in bone mass (osteoporosis or osteosclerosis), a decrease in bone mineral content (osteomalacia), or a combination of these abnormalities. It can provide no information about bone cell activity and bone turnover rate without bone biopsy.[2]

In current practice, no clear indication for bone biopsy exists in patients with osteoporosis. Most diagnostic procedures are restricted to atypical, unclear, and complicated cases, such as unexplained primary osteoporosis and failure to response to antiosteoporotic treatments.[2, 6]

On the other hand, bone biopsy remains the most accurate diagnostic tool to define alterations in bone morphology in patients with chronic kidney disease (CKD), known as renal osteodystrophy,[3, 7, 8, 9]  though it may not be practical in all such patients.[10] Clinical indications for performing the procedure are summarized below.

Renal osteodystrophy

Clinical indications for bone biopsy in patients with CKD stages 3-5, based on guidelines from Kidney Disease Improving Global Outcomes (KDIGO)[7, 11] and the Kidney Disease Outcomes Quality Initiative (KDOQI),[12]  are as follows:

• Unexplained fractures
• Unexplained hypercalcemia
• Unexplained hypophosphatemia
• Persistent bone pain
• Suspected aluminum toxicity based upon clinical symptoms or history of aluminum exposure
• Previous therapy with bisphosphonates
• Inconsistency among biochemical parameters, thereby preventing definitive interpretation
• Severe progressive vascular calcification
• Prior to parathyroidectomy if a history of aluminum exposure exists or if the biochemical determination is inconsistent with advanced secondary or tertiary hyperparathyroidism
• Intact plasma parathyroid hormone (PTH) levels between 100 and 500 pg/mL (in CKD stage 5) in association with unexplained hypercalcemia, severe bone pain, or unexplained increase in bone alkaline phosphatase activity

The 2017 update to the KDIGO guidelines stated that it is reasonable to perform a bone biopsy if knowledge of the type of renal osteodystrophy will impact treatment decisions.[13]

Osteoporosis

Clinical indications in the setting of osteoporosis are as follows:

• To distinguish osteoporosis from suspected osteomalacia and unexplained osteosclerosis ^[4]
• To evaluate diagnosis and treatment in atypical, unclear, and complicated cases, including unexplained primary osteoporosis, failure to respond to antiosteoporotic treatments, osteoporotic male or premenopausal osteoporotic female without endocrine abnormality, or suspected systemic or malignant disease (eg, mastocytosis, osteogenesis imperfecta, ^[14] nonsecreting plasmocytoma, and metastatic infiltration) ^{[2, 6]}

Bone tumors

Bone biopsy may also be indicated to diagnose either primary or metastatic bone tumors.[15, 16, 17]

Bone infections

Bone biopsy has been recommended for diagnosis of osteomyelitis.[18, 19]

Transiliac bone biopsy is contraindicated in the following patients:

• Those who have a coagulopathy or are on anticoagulant therapy
• Those who are grossly obese

Best practices

Transiliac bone biopsy should be performed by a skilled operator in an institute with a laboratory that can process undecalcified bone specimens, as well as experienced pathologists to analyze specimen data. The operator’s experience is an important factor in reducing morbidity and ensuring specimen adequacy.

Tetracycline double-labeling

If dynamic data on the new bone formation (eg, bone turnover, bone formation rates, and mineralization defects) are to be analyzed by using histomorphometry, then administration of time-spaced tetracycline markers is necessary before the bone biopsy.

Tetracycline compounds chelate calcium on bone surfaces and are deposited at the sites of active mineralization or new bone formation. Double-labeling of the bone with tetracycline should be completed before the bone biopsy is performed. The second dose of tetracycline is administered 10-14 days after the first dose. The amount of bone formed during that period can be calculated from the distance between the double bands of tetracycline fluorescence labels during histomorphometric evaluation.[3, 4]

Tetracycline markers viewed under fluorescent light reveal luminescent yellow-green bands within the bone. The separate dual bands indicate active mineralization of the new bone.

A number of different types of tetracycline compounds can be used, and each will fluoresce a different color. Tetracycline and demeclocycline are the most commonly used agents. The intensity of the label depends on the medication dosage. Tetracycline dosage for adults is 500 mg orally (PO) twice daily or 250 mg PO three times daily. Demeclocycline can be given 300 mg PO twice daily.[3, 4]

Several protocols for double tetracycline labeling exist, but the principle is to allow a certain amount of time between the two courses of the medications. A typical labeling schedule requires two 2-day or 3-day periods of tetracycline labeling, separated by a gap of 10-14 days between the two courses of tetracycline. Preferably, two different types of tetracycline compounds should be used. The second labeling should be completed 2-5 days before the biopsy.

The following is an example of a possible labeling schedule:

• Days 1-3 - First label, with tetracycline 250 mg PO three times daily (or 500 mg PO twice daily) for 3 days
• Days 4-13: No treatment (this period may sometimes extend for up to 14 days)
• Days 14-16 - Second label, with declomeclocycline 300 mg PO twice daily for 3 days
• 2-5 days after the last dose - Bone biopsy

The medication is usually administered after meals to avoid gastrointestinal discomfort. The dairy products and aluminum-containing antacids will interfere with adequate absorption and binding of tetracycline. Patients should be instructed to avoid milk and dairy products, as well as calcium-containing binders, for 2 hours before and after medication. Avoiding sun exposure while taking tetracycline prevents skin photosensitivity.

The patient should adhere strictly to the medication dosing and schedule to prevent problems in interpretation of the dynamic histomorphometry.

Complication prevention

The biopsy should be performed in a procedural room that is prompted to monitor a sedated patient during the procedure as well as in the recovery period. If moderate-to-deep sedation is required, medications should be administered by trained and credentialed personnel.[3, 20]

In hemodialysis patients, bone biopsy should not be performed on the dialysis day in order to avoid hematoma and bleeding from heparin exposure.

Peritoneal dialysis patients should be advised not to have a day dwell of dialysis fluid on the day of the biopsy. They should also be instructed to decrease the dialysate dextrose concentration the night before the biopsy; this helps prevent hypotensive episodes in the relatively dehydrated postdialysis patients.

Careful hemostasis during the procedure is required, particularly in patients with suspected bone tumors, because many tumors are hypervascular and can bleed profusely.

Most education initially includes indications for bone biopsy in the case, potential complications, and benefits from the result that will guide appropriate treatment.

Explain the nature of the procedure. The patient should be instructed to fast before the procedure because moderate-to-deep intravenous (IV) sedation might be required as well as local anesthesia at the side of biopsy.

Instruct the patient to take tetracycline and avoid certain diets, in case dynamic histomorphometry is planned after tetracycline double-labeling.

Advise the patient undergoing peritoneal dialysis (PD) not to have a day dwell of PD fluid on the day of the biopsy. Suggest to the relatively dehydrated postdialysis patient that the dialysate dextrose concentrate should be decreased on the night before the biopsy to prevent hypotension.

Most patients can go home on the same day of the biopsy except for selected cases, such as elderly or sick patients who might require an overnight stay.

Determine platelet counts and coagulation function. Thrombocytopenia and coagulopathy can potentiate bleeding after the procedure. Determine blood urea nitrogen (BUN) and serum creatinine. Renal failure can cause platelet dysfunction and increase the risk of bleeding.

Iliac crest biopsies can be obtained from either the right or left iliac crest in a horizontal and vertical direction. In either approach, equipment includes the following (see the image below)[3] :

• A pointed trocar with core diameter of 5-7 mm
• A guide sleeve with sharp, serrated edges
• A trephine biopsy needle
• A blunt extractor

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.

If an electric drill is to be used instead of the manual instruments listed above, equipment includes the following:

• Electric drill (see the image below)
• Funnel-shaped positioner
• Trephine that consists of a precutter drill bit and a core drill or actual trephine
• Scalpel with a No. 11 blade
• Keyhole surgical drape
• Blunt dissector
• Antiseptic solution
• Syringe (20 mL) and a selection of needles
• Skin suture with needle
• Stitch holder, scissors, and forceps
• Sterile gauze swabs and cotton wool balls
• Sterile universal container filled with 10% formalin
• Occlusive skin dressing

Electric drill for horizontal and vertical iliac crest biopsies. Image courtesy of Clin J Am Soc Nephrol 3:S164-S169, 2008.

Anesthesia

A combination of analgesia (fentanyl) with either sedation (propofol infusion) or a benzodiazepine (midazolam) has resulted in excellent biopsy conditions and rapid recovery. Local anesthesia should be used to decrease procedural stimulation and provide some postprocedure pain relief.

Positioning

In current practice, transiliac bone biopsy can be performed with the patient in either of the following two positions:

• Supine
• Lateral decubitus (left lateral decubitus for a right iliac crest biopsy, right lateral decubitus for a left iliac crest biopsy)

Vital signs should be monitored. Pulse oximetry and continuous cardiac monitoring are warranted in moderately sedated or deeply sedated patients.

After the procedure, the patient should be advised to maintain bed rest for 3-6 hours, mainly to allow the effects of the sedation to wear off. The patient can then get out of bed and go home the same day, except in selected cases where overnight monitoring is required.

At 24 hours after the biopsy, the patient should be instructed to remove the pressure dressing and replace it with a small adhesive pad. After 48 hours, the patient can shower, clean the incision site with soap and water, and then cover the site with a small adhesive pad.

At 7-10 days after the procedure, the sutures can be removed. The patient should be advised to watch for potential complications (eg, bleeding, hematoma, or skin infection).

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.

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.

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.

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.

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] :

• Pain
• Hematoma
• Wound infection
• Transient neuropathy
• Skin incision site infection
• Osteomyelitis
• Hip fracture
• Exostosis ^[21]
• Allergic reactions, gastrointestinal disturbances, and photosensitivity secondary to tetracycline intake

Class Summary

These agents inhibit growth of gram-positive and gram-negative bacteria.

Chlorhexidine gluconate (PerioGard, Peridex, Hibiclens, Avagard)

Chlorhexidine binds to negatively charged bacterial cell walls and extramicrobial complexes. It has bacteriostatic and bactericidal effects.

Povidone-iodine ophthalmic solution 5% (Betadine)

Povidone-iodine is an antibacterial agent with broad antibacterial and antiviral activity. No bacteria are known to be resistant to it.

Class Summary

Administration of intravenous midazolam in the operating room can reduce anxiety, tachycardia, and hypertension.

Midazolam

Midazolam is a short-acting benzodiazepine with a rapid onset of action. It depresses all levels of the CNS (eg, limbic and reticular formation), possibly by increasing activity of GABA.

Temazepam (Restoril)

Temazepam depresses all levels of the CNS (eg, limbic and reticular formation), possibly by increasing activity of GABA.

Class Summary

Induction of anesthesia is accomplished by using high doses of opioid (usually fentanyl or alfentanil) to maximize cardiovascular stability.

Fentanyl citrate (Duragesic, Abstral, Actiq, Fentora, Onsolis)

Fentanyl citrate is a synthetic opioid that has 75-200 times more potency and a much shorter half-life than morphine sulfate. It has fewer hypotensive effects than morphine and is safer in patients with hyperactive airway disease because of minimal or no associated histamine release. By itself, fentanyl citrate causes little cardiovascular compromise, although the addition of benzodiazepines or other sedatives may result in decreased cardiac output and blood pressure.

Fentanyl citrate is highly lipophilic and protein-bound. Prolonged exposure to it leads to accumulation of the drug in fat and delays the weaning process. Consider continuous infusion because of the medication's short half-life.

Class Summary

After standard monitoring equipment is attached and peripheral venous access achieved but before the arterial line is inserted, the midazolam or lorazepam dose is administered.

Propofol (Diprivan)

Propofol is a phenolic compound unrelated to other types of anticonvulsants. It has general anesthetic properties when administered intravenously. Propofol IV produces rapid hypnosis, usually within 40 seconds. The effects are reversed within 30 minutes, following the discontinuation of infusion. Propofol has also been shown to have anticonvulsant properties.