INTERVENTIONAL NEPHROLOGY AND DIALYSIS

Bone Biopsy: Indications, Techniques, and Complications

David Trueba, B. Peter Sawaya, Hanna Mawad, and Hartmut H. MallucheDepartment of Medicine, Division of Nephrology, Bone and Mineral Metabolism, University of Kentucky,Lexington, Kentucky

ABSTRACT

Bone biopsy is the gold standard for diagnosing the type andseverity of renal osteodystrophy (ROD) in end-stage renaldisease (ESRD) patients. In this article we review the indica-

tions, techniques, and complications of this minimally invasiveprocedure. The importance of careful preparation is empha-sized.

Bone biopsy is a minimally invasive procedure thatremains the gold standard for diagnosing the type andseverity of renal osteodystrophy (ROD) (1). Over the last60 years, much has been learned about the histologicpatterns of this disease. It is currently well establishedthat histologic changes are found in the bone of virtuallyall patients with end-stage renal disease (ESRD) (2).Despite advances in our understanding ofROD,wehaveyet to establish the optimal noninvasive method todetermine bone turnover, mineralization status, bonealuminum accumulation, or cellular abnormalities.Knowledge of these parameters in patients with renalfailure is important since they influence therapeuticdecisions. Bone biopsy is also useful in patients withosteoporosis, osteomalacia, osteogenesis imperfecta,Paget’s disease, and other metabolic bone diseases. Also,bone biopsy is utilized with increasing frequency inposttransplant patients (3). In addition to its clinical use,bone biopsy is done routinely for research purposes toevaluate the effects of new therapies on bone. Recentlymolecular histology such as immunohistochemistry andin situ hybridization histochemistry have emerged asvaluable tools to better understand the underlyingpathophysiology of the various metabolic bone diseases(4).

Clinical Indications

There are potentially many clinical indications forobtaining a bone biopsy in a patient with ESRD(Table 1). In patients with persistent and unexplained

hypercalcemia, a bone biopsy can assess for the presenceof aluminum, adynamic bone disease, or severe hyper-parathyroidism, particularly if the parathyroid hormone(PTH) levels are not excessively elevated or suppressed.Patients with persistent and unexplained hyperphos-phatemia (i.e., no evidence of dietary noncompliance)may have significant bone resorption despite onlymoderately elevated serum PTH levels. A bone biopsyin these patients will establish the diagnosis and confirmthe contribution of bone in the pathogenesis of hyper-phosphatemia.Symptomatic patients with unexplained bone pain or

fractures could have any formofROD. In these patients,if PTH levels are not remarkably elevated to suggestsevere hyperparathyroidism, the underlying diagnosisthat would explain the symptoms can be very difficult toestablish without a bone biopsy. Similarly, asympto-matic patients with moderately elevated PTH levels (i.e.,200–400 pg/ml) may not necessarily have underlyinghyperparathyroid bone disease that requires the use ofvitamin D (5).Whenever aluminum-related bone disease is suspec-

ted, a bone biopsy is particularly helpful in making thediagnosis and guiding the therapy by evaluating theextent of aluminum accumulation. Finally, prior toparathyroidectomy, a bone biopsy represents the onlyunequivocal tool to rule out aluminum accumulationand to confirm excessive PTH activity.

Techniques

Preparation

Thorough preparation for a bone biopsy is essential.As with any invasive procedure, a history and physicalmust be completed. Particular emphasis shouldbeplacedonmedications, allergies, and comorbid conditions, suchas cardiopulmonary diseases, thatmayneed stabilizationprior to the biopsy. Routine preoperative examinationwithin 2–3 weeks of the procedure should include

Address correspondence to: Hartmut H. Malluche, MD,University of Kentucky Medical Center, MN S64, 800 Rose St.,Lexington, KY 40536-0298, or e-mail: hhmall@pop.uky.edu.

Seminars in Dialysis—Vol 16, No 4 (July–August) 2003pp. 341–345

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complete blood count with differential, comprehensivemetabolic panel, prothrombin time, activated partialprothrombin time, electrocardiogram, and chest radio-graph. Hemodialysis (HD) patients should be dialyzedthe day before the biopsy with very minimal or noheparin. They should not be dialyzed the day of theprocedure and, if possible, the day after the procedure.Heparin use should be minimized for one to two dialysissessions thereafter. Peritoneal dialysis (PD) patients canperform an exchange the morning of the procedure, butmust have the biopsy done with an empty abdominalcavity. Coumadin, aspirin, and clopidogrel should bestopped 1 week prior to the biopsy and restarted 1 weekafter. Patients with potential bleeding disorders such asliver failure may require fresh-frozen plasma andplatelets prior to the procedure, depending on theircoagulation studies.A very important step in bone biopsy preparation is

in vivo labeling of bone. Strict compliance with theinstructions of this step must be stressed to patients toensure that the specimen is of excellent quality. Currentlylabeling is done with antibiotics from the tetracyclinefamily because they are nontoxic, bind to activelyforming bone surfaces, and have spontaneous fluores-cence. As part of the history, patients should be askedabout previous use of tetracycline. Recent use oftetracycline to treat an infection may hinder the pathol-ogist in evaluating the specimen. Histologic inter-pretation can also be difficult if the medication isinadequately absorbed during the labeling regimen.For example, insufficient labeling can occur if the patienthas amalabsorption syndrome or is taking the antibioticwithmeals, dairy products, iron-containingmedications,calcium supplements, or an antacid. In the case of amalabsorption syndrome, increasing the dose of themedication is warranted.A double-labeling technique, inwhich a period of time

elapses between two courses of antibiotics, is optimal.This technique provides the best information on miner-alization rate and bone formation. In our center we use atetracycline regimen of on for 2 days, off for 8–15 days,on for 4 days, followed by the biopsy within 4–6 days ofthe last dose. The dose of tetracycline hydrochloride is500 mg by mouth three times a day in patients withnormal kidney function and 500 mg by mouth twice aday in those with renal failure. A shorter regimen can beused if the bone biopsy is urgently needed. This regimenconsists of a tetracycline dose of 1.0–1.5 g/day bymouth,on for 1 day, off for 6 days, on for 1 day, with the biopsy24–48 hours after the last dose.

Common side effects of tetracycline include photosen-sitivity, vomiting, diarrhea, and allergic reactions amongothers; the higher dose may also result in increasedgastrointestinal side effects. Another regimen for thedouble-labeling technique involves using tetracycline forthe first label and demeclocycline for the second,with thetime intervals remaining the same. Tetracycline fluores-ces light yellow, demeclocycline a yellow-orange. Thistwo-drug technique may allow for better assessment ofthe mineralization rate. The dose for demeclocycline is300 mg by mouth three times a day or 300 mg by mouthtwice a day for patients with normal or impaired kidneyfunction, respectively.

The Procedure

The best and most commonly used site for the bonebiopsy is the anterior iliac crest. This site is associatedwith the fewest postoperative complications, is easilyaccessible, and is not as invasive as other procedures,such as obtaining a rib biopsy. In addition, rib biopsies inpatientswithmetabolic bonediseases havean inadequateamount of cancellous bone tissue. Some debate existsover the best approach to use in obtaining a bone biopsyfrom the iliac crest, the vertical versus the horizontal or‘‘through-and-through’’ technique (Fig. 1).We advocate the use of the vertical approach for

various reasons. First, an electric drill is used with thevertical approach, as opposed to the manual trocar usedwith the horizontal method, resulting in less physicalpressure being applied to the bone and patient. Thispressure differential potentially results in less damagedbone and less trauma. Second, hemostasis is easilyaccomplished with the vertical approach, as it onlyresults in one hole in the patient’s iliac bone, which isreadily accessible and compressible. The horizontaltechnique leaves two holes in the patient’s pelvis. Theinternal hole is inaccessible for compression shouldbleeding occur. Third, with the horizontal method, thesample size is limited by the thickness of the iliac bone. Incontrast, the vertical method yields a longer sample,typically 2.5–3.5 cm long. This length allows forassessment of not only the cortical bone and subcorticalcancellous bone, but also the deep cancellous bone thatthe horizontal specimen is unable to provide. Finally, the

Fig. 1. Bone biopsy techniques. Cross-section of the anterior iliac

crest: (A) vertical approach; (B) horizontal approach (through-and-

through).

TABLE 1. Potential clinical indications of bone biopsy in ESRD

patientsa

Persistent and unexplained hypercalcemiaPersistent and unexplained hyperphosphatemiaUnexplained bone pain and fracturesModerate hyperparathyroidismSuspected aluminum-related bone diseaseSuspected osteomalaciaPrior to parathyroidectomy

aSee text for a discussion.

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two cortices of bone obtained with the horizontaltechniquehavenotbeen shown toprovide anyadditionalhistologic information.The day of the bone biopsy the patient should beNPO

(nothing by mouth) for at least 6 hours prior to theprocedure. Morning medications can be taken with justsips of water. An informed consent should have beenobtained as part of the preoperative process. Theprocedure is done in an outpatient operating room orin a procedure room setting, as maximum sterility andcardiovascular monitoring are important. In our centerwe utilize an outpatient operating room and providegeneral anesthesia. The anesthesiologist typically uses alaryngealmaskairwaydevice for airwayprotection, sincetheprocedure is relatively short.However, thebiopsy canbe easily done with conscious sedation in a regularprocedure room.The patient is placed in a supine position with the

biopsy leg rotated outward and a supportive pad isplaced under the hip to be biopsied. After locating theanterior iliac crest, the area is disinfected with betadinesolution and a sterile field is created. Lidocaine 1%without epinephrine is infiltrated generously (10–15 cc)to an area 2–5 cm behind the anterior iliac spine. Themedial and lateral iliac walls, as well as the surroundingsubcutaneous tissue, are also infiltrated with lidocaine.The periosteum should be adequately infiltrated. In theobese patient, the whole body can be tilted to one side soas to allow gravity to aid in exposing the biopsy site. Ifthis is not feasible, the excess tissue can be moved asidewith straps of 2-inch tape. If the anterior iliac crest is stillnot accessiblewith the abovemeasures, the posterior iliaccrest can be used, just lateral to the sacral-iliac joint.The electric drill we employ is a newer model

(Straumann, Cambridge, MA; Fig. 2) which works likethe established electric drill but has the added feature of aone-step drilling and extraction process, therefore shor-tening the surgical time and making the proceduresimpler. The drill is set up by first attaching the ejector,followed by the extractor, and finally either the precutteror trephine, depending on whether the drilling is forsubcutaneous tissue or for bone, respectively (see below).The drill bits are disposable, which decreases theinfection risk, ensures sharp tools, and eliminatespotentially weakened drill bits that may occur as a resultof frequent sharpening.

The physician holds the iliac crest between two fingersand makes a longitudinal incision of 0.5–1 cm with ascalpel right over the anterior iliac crest. This is followedby blunt dissection of the subcutaneous tissue withscissors or a hemostat until the upper surface of theanterior iliac crest is exposed. Additional lidocaine to theperiosteum with direct visualization might be helpful atthis stage. The funnel (Fig. 2) is now introduced throughthe incision and placed over the exposed iliac crestsurface in the centerbetween themedial and lateral edges.The axis of the funnel should be aligned with the axis ofthe underlying bone. This prevents the trephine fromexiting through the pelvic bone during the drillingprocess.The precutter is used first to remove the subcutaneous

tissue and some of the periosteum. It is placed in thecenter of the funnel and the electric drill is engaged bypressing the first trigger (Fig. 2, upper button). Theprecutter should not go into the bone. Next, the trephineis placed in the funnel in the same fashion. Drillingshouldbedonewithminimal pressure toavoid collapsingthe cancellous bone. Some resistance can be expectedwhile drilling. However, a considerable amount ofresistance might indicate that the trephine is drilling intothe sidewall of the cortex. If this is suspected, the trephineshould be pulled out and the axis of the funnel readjustedto ensure adequate sampling of the cancellous bone. Thedrilling continues until the base of the drill just reachesthe bottom of the funnel, without touching it. At thisstage, the sleeve of the drill is pulled slowly upward whilecontinuing to drill. This process allows the extractionforceps to move over the bone core and capture thesample. The entire trephine can now be removed slowlyupward while the drill is still rotating.As soon as the trephine has exited the body, a sterile

medical wax plug in the form of a cylinder should beplaced almost simultaneously into the cavity created bythe trephine. This should minimize bleeding andprevent hematoma formation. The wax is neatly packedwith the tip of a forceps wrapped in gauze to avoidadhesion of the wax to the metal of the forceps. Excesswax should be meticulously removed and the surface ofthe plug must be below the edges of the bone cavity toprevent contact with local tissue and avoid an inflam-matory reaction. If excessive bleeding is noted, gelfoamfollowed by the wax plug can be used, and if absolutelynecessary, liquid thrombin can be injected through thewax plug and into the gelfoam to further aid inhemostasis.Thephysician ejects thebone core sampleontoa sterile

sheetwhile pressing the secondbuttonon the drill (Fig. 2,lower button). An adequate specimen should be 2–3 cmin length and 4mm in diameter, and it should consist of alayer of upper cortical bone with subcortical and deepcancellous bone (Fig. 3). The sample should be picked upgently with forceps and placed in a 100% ethanolcontainer.Once the specimen has been secured, the surgical

area is thoroughly irrigated with a saline solution andthe incision is closed in two layers; first the subcuta-neous tissue with absorbable sutures and then the skinusing 3-0 nylon. Antibiotic ointment is applied over theFig. 2. Bone biopsy drill and funnel.

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incision, followed by an eye patch and Tegaderm. Ice isleft on the area for 1–2 hours to ensure hemostasis andto keep any swelling to a minimum. If the patient hasan increased risk of bleeding, an abdominal circularbinder can be used to put pressure on the biopsy site.The total time of the procedure from the first incision tothe last suture generally takes approximately 15–20minutes.

Postprocedure

Postoperative instructions to the patient includekeeping the wound dry for at least 48 hours. The patientshould not drive a car immediately after the procedureand should not do any heavy lifting, severe straining, orstair climbing for at least 4 days. Any sign of infection orbleeding shouldbe reported immediately to the physicianwho performed the biopsy. The patient, as well as thepatient’s primary carephysician, shouldbe informed thatfuture radiographs of the pelvic bone may show anartifact in the area of the bone biopsy and this is of noconcern.The bone biopsy specimen must pass through five

steps in the bone histology laboratory: fixation, dehy-dration, embedding, sectioning, and staining. A 100%ethanol solution is the best fixative currently used forroutinemineralized bone histology given that it preservesthe tissue well and does not leach out the calcium. Thedehydration step starts after the sample has beenimmersed in 100% ethanol for 24–48 hours, dependingon the size of the sample. This dehydration step isrequired since the embedding media is not miscible withwater. Embedding is done with methyl methacrylatebecause it penetrates the specimen quickly, is nontoxic,does not cause artifacts such as bubbles, and has thenecessarydissolving solvents.Thenext step, sectioning, isaccomplished with special microtomes implanted withdiamond knives or carbide edges. Staining is the last partof the preparation. Various stains and techniques areavailable depending on what is being investigated, buttheir descriptions are beyond the scope of this article. Onaverage it takes at least 10–14 days before the biopsyslides are ready for interpretation.

Complications

Potential complications include bleeding, hematoma,infection, superficial nerve injury, and pain. The overallfrequency of complications is 0.52%, as reported by

Duncan et al. (6), based on a questionnaire sent to 18different hospitals accounting for 14,810 biopsies. Thehorizontal approach had a complication rate of 0.63%,while the vertical approach was 0.36%. Bleeding andhematoma are reduced to a minimum with the verticaltechnique and when all necessary precautions have beenundertaken. Likewise, infection risk is not greater than1% if sterile precautions are followed. If infections dooccur, they are usually related to inappropriate postop-erative wound care. More specific to bone biopsyprocedure is the potential formation of a granuloma asa result of wax debris that migrated from the bone cavityor was not adequately removed. Superficial nerve injuryresults when a superficial nerve, such as the nervuscutaneus femoralis, is accidentally lacerated. Becausenerves of the peripheral nervous system can regrow,resolution of the symptoms created by the laceration canbe expected. Lastly, the pain associatedwith bone biopsyvaries, depending on the patient. Most patients willreport ‘‘soreness’’ over the area lasting 4–5 days.

Training Process

At the University of Kentucky Division of Nephrol-ogy, Bone and Mineral Metabolism, more than 30practicing nephrologists from throughout the UnitedStates have been trained in the past 2 years to confidentlyand independently perform bone biopsies. The trainingprocess involves spending at least 1 full day in theoutpatient operating room with one of our experiencednephrologists.After observingoneprocedure, the traineeis observed and coached through as many biopsies asnecessary to become proficient in the process. Usuallytwo or three biopsies are sufficient for adequate training.Once proficiency in the procedure has been demonstra-ted, the physician receives a certificate attesting to his/hercompetence. To obtain temporary clinical privileges, thephysician must hold a license to practice medicine in anystate and must have a valid U.S. Drug EnforcementAgency (DEA) registration and malpractice insurance.

Conclusion

Bone biopsy remains the gold standard for theevaluation of ROD. Its role in the management ofpatients with ESRD is valuable and sometimes indis-pensable. The procedure is minimally invasive and isperformed on an outpatient basis. It is well tolerated andsafe if carried out by an experienced and properly trainedphysician.

References

1. MallucheHH, LangubMC,Monier-FaugereMC: The role of bone biopsy inclinical practice and research. Kidney Int 56(suppl 73):20–25, 1999

2. Malluche HH, Ritz E, Lange HP, Kutschera K, Hodgson M, Seiffert U,Schoeppe W: Bone histology in incipient and advanced renal failure. KidneyInt 9:355–362, 1976

3. Monier-Faugere M-C, Mawad H, Qi Q, Friedler R, Malluche HH: Highprevalence of low bone turnover and occurrence of osteomalacia after kidneytransplantation. J Am Soc Nephrol 11:1093–1099, 2000

Fig. 3. Example of an adequate sample of extracted bone tissue.

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4. Langub MC, Faugere MC, Malluche HH: Molecular bone morphometry.Pediatr Nephrol 14:629–635, 2000

5. Qi Q, Faugere MC, Geng Z, Malluche HH: Predictive value of serum para-thyroid levels for bone turnover in patients on chronic maintenance dialysis.Am J Kidney Dis 26:622–631, 1995

6. Duncan H, Rao SD, Parfitt AM: Complication of bone biopsy. In: Jee W,Parfitt A (eds). Bone Histomorphometry. Paris: Societe Nouvelle de Publica-tions Medicales et Dentaires, 1981:247

Whose Can Was It Anyway?

In 1954, young Bruno Watschinger of Linz was sent by his boss, Professor Fellinger, to America tolearn about medicine. At that time, Austria was still divided among the Allied armies anddevastated by the war. A World Health Organization (WHO) fellowship allowed a visit of just 3months, which began in January 1955. Watschinger went to Cleveland to study generalmedicine and hypertension with Irvine Page, but in the end spent all his time with Willem Kolff,who had been in Cleveland for 5 years. His work with the rotating drum artificial kidney did notseem to be of much use at first to Watschinger, as there was no dialysis in Austria and themachine was far too complex and expensive for Austria. Clearly something much simpler wasneeded, but it also had to be powerful, unlike the flat-plate dialyzers available at that time.Watschinger put the problem to Kolff, the supreme inventor: In only 2 months, Watschinger, withKolff’s help—who was preoccupied with developing an artificial heart—built a simple androbust, single-use disposable twin-coil dialyzer.

The design was based on the work of surgeons William Inouye and Philip Engelberg, whomKolff had met in Philadelphia, where they had built a coil kidney using a domestic pressurecooker as a rigid outer jacket, thus permitting controlled ultrafiltration. This idea of a coil insteadof a spiral dialyzer was new, although on a visit to Sweden in 1948, Kolff met Bodo von Garrelts,who had built a coil kidney wound with a rigid backing.

The new coil dialyzer was quickly cobbled together from available domestic materials, usingfly screen from a stable porch to give stability and rigidity, as well as permitting dialysate to flowand mix. The wide cellophane tubing came from a sausage manufacturer. There wereproblems with assembly, so Kolff built a machine to wind and stitch the coils in his garage. Butsomething was needed on which to wind the coil, to make the priming volume small: used canswere the answer—but which? Watschinger says that Dole pineapple cans were used becauseof their large diameter; Kolff says that orange juice cans and beer cans were also used. Thepicture in Watschinger’s article (1) (Fig. 4) of several prototypes shows that the can nearest thesize of the commercially manufactured dialyzer is labeled ‘‘Monarch.’’

The resulting dialyzer was presented to the first meeting of the American Society of ArtificialInternal Organs (ASAIO) in September 1955 by a nervous Watschinger, who had never given atalk in English before. With characteristic generosity, Kolff offered his and Bruno’s coil kidney tocommercial laboratories for manufacture, but was turned down. Finally, he approached theTravenol Corporation, who agreed to put it into production, and by the end of the 1950s, therewere nearly 200 Travenol ‘‘twin-coil’’ units in the United States alone. It permitted dialysis to beeasily set up in any hospital—at a price: each disposable coil cost nearly $1000 (in today’sdollars), and the machine cost nearly $20,000! Needless to say, Bruno used the kidney—againstconsiderable opposition—when he returned to Vienna, and then to Linz. The nuns in charge ofhis hospital allowed large debts to accumulate, as he dialyzed more and more patients.

Acknowledgments

I thank Bruno Watschinger for additional information. Use was also made of the ISN VideoLegacy archive interview with him in 1999.

Reference1. Watschinger B: From the rotating drum to the pineapple-can coil kidney: the unpublished history of the twin-coil.

Int J Artif Organs 9:870–876, 1995

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