Use of Radiofrequency Ablation in the Treatment of Bone · PDF file · 2015-07-23Use of Radiofrequency Ablation in the Treatment of Bone Tumors ... tion zone enabling a higher rate

Use of Radiofrequency Ablation in the Treatment of Bone Tumors

Matthew R. DiCaprio, M.D., Joseph M. Bellapianta, M.D.

Summary: Radiofrequency ablation is a well-established treatment tool utilized inmusculoskeletal oncology. It is a safe, minimally invasive, and cost-effective treatmentfor many lesions. Most frequently utilized for treating osteoid osteomas, the techniqueis also helpful for controlling selected lesions from metastatic bone disease and otherbenign bone disorders, such as, chondroblastomas and osteoblastomas. The procedurerequires considerable preoperative planning and organization to assure a smooth,efficient experience. Our intent is to review the indications for radiofrequency ablationas a treatment option for musculoskeletal tumors and to give a detailed description ofthe planning, set-up and technique of the procedure. Key Words: Radiofrequencyablation—RFA—Osteoid osteoma—Metastatic bone disease—Minimally invasive.

Radiofrequency ablation (RFA) is a relatively newtechnique for the treatment of bone tumors that offersreduced morbidity with excellent success. In RFA, alter-nating current (100–500 kHz) is delivered to pathologictissue by the probe tip. This causes ionic agitation andfrictional heat that causes local tissue coagulation in asmall area around the tip of the probe.

Many companies are currently distributing RFA de-vices for clinical use including: Boston Scientific, RITAMedical System, Radionics, Tyco Healthcare, and Ber-chtold Medical Electronics. Although the RITA andRadionics devices are most well known to these authors,a similar tissue response and safety profile can be ex-pected from all approved devices (Figs. 1 and 2). TheRITA device consists of a 50 to 150 W alternatingcurrent generator and a 15-gauge electrode. The probehas a movable hub and eight retracting curved electrodesthat are deployed from the tip after its positioning intothe tumor. An array electrode can increase the coagula-tion zone enabling a higher rate of complete necrosis.The probe tips can be seen on computed tomography(CT) scan and can be adjusted based on the area intendedto treat. Each needle tip can also register the temperaturein the heated area. Radionics distributes a probe that

consists of a straight needle with an internal channel.Inside this channel, saline solution circulates for cooling.Holes are present to permit the leakage of saline solutionto increase tissue conductivity.

Radiofrequency ablation is most often used for treatingosteoid osteomas, but its indications are expanding to in-clude other benign and malignant lesions such as chondro-blastoma and metastatic bone disease. Osteoid osteoma is abenign, bone-forming tumor that most commonly occurs inchildren and young adults. It classically produces pain thatis worse at night and relieved by anti-inflammatory medi-cation. The nidus in the center of the tumor rarely exceeds1.5 cm in diameter.2 Classically, they arise in diaphysealbone, however, they have also been reported in the epiph-yseal and metaphyseal bone of the axial and appendicularskeleton.11 Although there is evidence that many of theselesions will regress spontaneously, patients are usually un-willing or cannot tolerate prolonged NSAID use and theunpredictable duration of the disease.

Historically, these lesions were widely excised withopen surgical procedures.18,19 The development of lessinvasive techniques have been explored by many authorsto avoid the complications of wide open excision such asinfection, soft tissue damage, creation of a stress riser,increased postoperative pain, and difficulty finding thelesion.16 It is also more cost effective.3 Radiofrequencyablation provides an attractive alternative to open exci-sion of the nidus and is a superior alternative for mostuncomplicated cases of osteoid osteoma. In addition,

From the Department of Orthopedic Surgery, Albany Medical Center,Albany, New York.

Address correspondence and reprint requests to Matthew R. DiCaprio,MD, 530 Liberty Street, Schenectady, NY 12303. E-mail: [email protected]

Techniques in Orthopaedics®

22(2):99–109 © 2007 Lippincott Williams & Wilkins, Inc.

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RFA is well established as having a high success ratewith a low incidence of complications.4,15 This is true forboth primary lesions and recurrences after attemptedopen surgical procedures.13

It is our intent to share with the orthopaedic commu-nity our preoperative thought process, a detailed step-bystep account of our room set-up and procedure, and whatto expect postoperatively.

INDICATIONS FOR RFA FOR BONE LESIONS

In addition to using RFA for osteoid osteoma, reportsof using computed tomography (CT) guided-RFA for thetreatment of other bone lesions are increasing. Bonemetastasis measuring as large as 7 cm in size have beentreated successfully with this technique.6 Radiation ther-apy is the current standard of care for local treatment oftumors, however, it may be contraindicated or not effec-tive for pain relief. Many physicians are consideringRFA an option for pain relief in metastatic diseasebecause of the reasonable early results and reducedmorbidity for the patient12,20 Kojima et al. have alsoshowed good pain relief using RFA for the treatment ofmetastatic bone lesions.14 Good outcomes with painrelief have also been reported with radiofrequency abla-tion of spine metastases.7,8

In 2004 Goetz et al. reported on 31 patients who wheretreated with RFA of metastatic disease for pain relief. Amulti-tip needle probe was inserted into the lesion andheated to 100°C for 5 minutes. Pain scores decreased froman average of 7.9/10 before the procedure to 3.0/10 and1.4/10 at 12 and 24 weeks, respectively, after the procedure.Opioid usage was also significantly decreased. Three com-plications were noted including a skin burn from the ground

pad, transient bowel and bladder incontinence from treat-ment of a sacral lesion, and an acetabular fracture aftertreatment of an acetabular lesion.1

The minimally invasive technique used with CT-guided RFA has increased the armamentarium for treat-ing difficult to access lesions. A primary example wouldbe chondroblastoma of the femoral head. Although com-plication rates may be significant because of the closeproximity of the probe tip to the joint surface, thistechnique may be an attractive option compared with anopen procedure.17 Open treatment of chondroblastoma ofthe femoral head poses a significant risk to the vascular-ity of the femoral head, the articular cartilage, the growthplate, and also increase the risk for postoperative frac-ture. Osteoblastoma may also be treated with RFA in thefuture with multiple sites of treatments or a larger probeto target the larger lesion. There is limited data in theliterature to truly know the efficacy for lesions other thanosteoid osteomas and metastatic bone disease. One mustbe careful in applying this technique without carefulpreoperative diagnostic imaging since tissue cannot reli-ably be obtained for definitive histologic diagnosis.

PREOPERATIVE EVALUATION

Diagnosis of bone lesions is beyond the scope of thisreview, but it cannot be overstated the importance of theinitial patient evaluation at arriving at an accurate clini-cal and radiographic diagnosis. Patients with osteoidosteomas will frequently present with a classic history ofpain relieved by NSAIDs, but this will not be true in allcases. Radiographic assessment with thin cut CT withcoronal and sagital reconstructions will usually identifythe nidus of an osteoid osteoma better than magnetic

FIG. 1. RITA equipment. (A) Bone introducer, (B) probe, (C) probe tip electrode configuration, (D) despersion pads, (E) RITA radiofrequencygenerator.

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Techniques in Orthopaedics®, Vol. 22, No. 2, 2007

resonance imaging (MRI). Bone scans are useful fortargeting the lesions when plain radiographs do notdemonstrate the lesion. It is not uncommon in the pedi-atric population to have varied lower extremity paincomplaints secondary to referred pain that can lead tomany unnecessary imaging modalities on incorrect re-gions of the patient. A dynamic contract CT can also beused when trying to distinguish between a nidus ofosteoid osteoma and a Brodie’s abscess.

PREOPERATIVE PLANNING

Once a lesion amenable to RFA is found and thediagnosis is confirmed radiographically, the patient can

be scheduled for outpatient radiofrequency ablation. Theprocedure usually takes approximately 1 to 1.5 hours andrequires the collaborative efforts of the radiology, anesthe-sia, and operating room staff. All anesthesia equipment andthe sterile equipment needed for the procedure are broughtinto the room with the CT scanner. It is useful to have achecklist to be assured that all personnel, rooms, and equip-ment necessary for the procedure will be available (Table1). This will increase the efficiency of the procedure andhelp avoid frustration. For larger patients make sure theweight limit of the CT table can safely support the patient.

The surgeon should preoperatively plan the startingposition and angles anticipated to safely and accuratelyenter the lesion using X-rays or CT scans if available.

FIG. 2. Radionics equipment (A) Binopty biopsy/drill set insert, (B) radionics probe through binopty cannulated system, (C) radionicsradiofrequency generator.

101RADIOFREQUENCY ABLATION


Areas with important neurovascular structures should beavoided if possible because working around these struc-tures can lead to inadvertent injury. Open surgical re-moval of the nidus should be considered if it is within 1or 1.5 cm of important neurovascular structures.5,18 Theskin should also be respected as severe burns have beenreported.10 When planning a point of entry for the boneintroducer or drill bit it is helpful to choose a flat bonesurface that is perpendicular to the lesion. To avoid neuro-vascular structures and to assist with patient positioning it isnot uncommon to drill through the anterior cortex of a boneto get to the lesion on the posterior cortex.

PROCEDURE ROOM SET-UP

It is preferable to have a large CT room to house allof the equipment, and personnel needed to safelyperform the procedure (Fig. 3). A sterile table will beneeded for the surgical equipment and space will also beneeded for the anesthesia and RF ablation machines. Theanesthesiologist and anesthesia machine are preferablyon the opposite side of the patient from the surgeon toallow for maximum access to the patient and to reducethe chance for sterile table contamination. A radiologytechnician, circulation nurse, anesthesiologist, and sur-geon are usually the only people needed, however, aradiologist and surgical assistant may also be an asset.

The sterile surgical equipment that should be availableis: skin prep solution, draping supplies, local anesthetic,number 11 blade, gauze, drill with multi-size drill bits,bone introducer, RF probe and cord, saline, suture, anddressings (Fig. 4A). Confirm that all equipment ispresent and working properly before any anesthesia isadministered. Two dispersion (grounding) pads shouldbe placed on the patient with good skin contact. The padsshould be placed approximately equidistant and in oppo-site directions from the operative site. Correct placementof these pads is a critical step in the procedure and shouldnot be delegated to other members of the team. This stepshould follow strict product manufacturing recommen-dations (see Appendix at end of article).

ANESTHESIA

General anesthesia or a spinal block is generally pre-ferred to conscious sedation and local anesthesia for boththe comfort of the patient and facilitation of ablating thelesion. Younger patients can often remain anxious withsedation even if they are pain free because of the unfa-miliar environment and emotional stress of the proce-dure. In addition, patients will often uncontrollably movethe effected limp during the ablation or imaging stagesthat can result in movement of the probe or additionalradiation exposure needed.

PATIENT POSITIONING ANDLESION TARGETING

Once the patient is under anesthesia, the next task isto determine the correct starting point. The anticipated

TABLE 1. CT-Guided Radiofrequency AblationProcedural Checklist

Patient Name: ____________________________________Scheduling:Reserve CT unit� Date ____________________� Time ____________________Anesthesiologist available for procedure� Put on OR schedule to assure staffing� RITA generator available� RITA representative present� Probes availableSterile Equipment Other Equipment� RITA Starburst XL probe � Marking pen� RITA Bone Introducer � Duraprep or betadine� 2% lidocaine � Razor� NS 0.9% 10 ml � Bandaids� 10 ml syringes � Grounding pads (RITA)� 18 g needles� 4 � 4s� 11 blade� Packet of blue towels� Fenestrated large sterile drape� Surgical gowns� Specimen container� Surgical gloves� Steri-strips� Battery powered drill� 2.5 mm and 3.5 mm drill bit� 4-0 Nylon suture

FIG. 3. CT-suite set-up. (A) CT gantry with patient, (B) anesthesiaequipment, (C) procedure equipment table, (D) ablation machine.



path that the probe will follow should be plannedpreoperatively. A grid can be placed on the patient’sskin over the working area before the first CT scan tohelp with localization of a starting point (Fig. 4B).Markings on the grid can be seen on the CT scan andcan be used to estimate distance across the skin (Fig.5A). For example, the starting point may be betweenthe 3rd and 4th line on the grid in the medial to lateraldirection. Proximal to distal movements can be esti-mated by using the CT slice thickness and countinghow many images the lesion is from a point ofreference.

CT TECHNIQUEBefore beginning the procedure, a dose of intrave-

nous prophylactic antibiotic is given to the patient. Afirst generation cephalosporin or equivalent is appro-priate. Once the patient is anesthetized and on the CTtable, a preliminary study is done with wide cuts (3.0mm cuts) to localize the lesion. Next, the imaging areais narrowed and the slice width is decreased to 1 mmsections to assist with targeting the center of thelesion. The small area to be ablated can be repeatedlyscanned when drilling to confirm that the angles anddepth of drilling is correct.

FIG. 5. Step-by-step RFA procedure. (A) Initial scout with skin grid for targeting lesion, (B) mark skin using lights from scanner, (C) drill intocortical bone, (D) place bone introducer through cortical hole made with drill bit, (E) CT image with bone introducer, (F) place ablation probe throughintroducer, (G) CT image with probe in center of lesion, (H) add saline to the system to lower impendence, (I) start ablation 90°C for 4 to 6 minutes.

FIG. 4. (A) Equipment table, (B) skin markinggrid for localization with CT.



Lead is usually not required for the procedural team asthe surgeon can safely and sterilely enter the CT controlroom during scanning. Retreat into the control room alsoallows the surgeon to read the images in real time tomake any adjustments of the probe. A lead apron usuallycan be placed on the patient except in certain pelvic orsacral lesions.

BONE INTRODUCER PLACEMENT

After the skin is marked the region can be prepped anddraped for the procedure (Fig. 5B). An 11 blade is usedto puncture the skin and the bone introducer can beplaced. If thick cortical bone needs to be penetrated toaccess the lesion, a drill bit will be necessary to facilitateplacement of the introducer. A drill guide should beinserted to protect soft tissue and pressed firmly againstthe bone. A 3.5 mm drill hole should be made in the nearcortex (Fig. 5C). The bone introducer can then be in-serted into the hole and advanced at the presumed anglenecessary to enter the center of the lesion (Fig. 5D). Onceresistance is encountered, a repeat CT should be done toconfirm that the needle is pointing toward the lesion (Fig.5E). A goniometer can be used on the CT monitor toestimate any adjustments to precisely adjust the angle ofadvancement into the lesion.

Once the tip of the introducer is confirmed in thecenter of the lesion, the center portion can be removedand a core biopsy of bone can be removed and sent forpathology evaluation. This is often not done, however,because it usually does not change management and thecore biopsy frequently does not yield adequate tissue tomake a diagnosis.18

PROBE PLACEMENT AND RFA

The tip of the RF probe can then be inserted into theintroducer and advanced to the lesion (Fig. 5F). This tipposition should also be confirmed with another CTimage to assure the final position is correct (Fig. 5G).Several tips are available including a single tip probe toprecisely deliver heat from one point and a multi-tip thathas an umbrella type array of electrodes at the end for alarger area of treatment. The divergence of the probes onthe multi-tip can be adjusted to broaden or narrow thearea of treatment and the individual probes can usuallybe seen on CT. This is one of the key differences amongmanufactures. Rita medical systems only use umbrella-type multi-tip probes and Radionics only has single-tipprobes. For treatment of an osteoid osteoma, a singleprobe with approximately 5 mm of exposed tip is all thatis required since the nidus is �1.5 cm. When treating

metastatic bone disease the lesions vary substantially insize and having a multi-tip probe becomes handy andallows for a broader area of tissue necrosis with eachRFA cycle. With the tip of the probe in position, thecorrect end of the cord can be passed off and pluggedinto the RF machine. The cord should be secured to thepatient with one or two clamps to avoid any tractionwhile the CT table moves in and out of the scanner. Allequipment should be inspected before each CT scan isperformed to assure it will not be incidentally displacedwhen the table moves into the scanner. It is important toadd saline to the system to help decrease impedance andfacilitate ablation without over “cooking” the lesionalarea (Fig. 5H).

The settings on the RF machine we use are 90°C for 4to 6 minutes with a power of 100. The machine willslowly raise the temperature and start a timer when 90°Cis reached (Fig. 5I). After the 4 to 6 minutes is complete,the machine will cool down back to room temperature.The probe can usually be removed before cool downfinishes. Rosenthal et al. use these same parameters fortreatment of osteoid osteomas.2 There is more discrep-ancy in length of ablation time than ablation temperaturefrom institution to institution. Ablation times vary from2 to 8 minutes. The only basic research evaluating thezone of tumor necrosis or kill is based on one dog studythat demonstrated approximately a 1 cm necrosis zonefrom the tip of the probe when using 80°C for 4 minutes.

SPECIFIC CONSIDERATIONS BASED ONLOCATION OF TUMOR

RFA of spinal lesions put the dura and neural struc-tures at risk therefore conscious sedation and local an-esthesia is preferable in this setting to allow bettermonitoring of the patients.9 Complications can be re-duced by interrupting treatment or repositioning theprobe if local temperature rise begins to cause symptoms.Gronemeyer et al. used RFA to treat 10 spine lesionsranging from 1.5 cm to 9 cm with good pain relief and nocomplications.7

Chondroblastomas located in the femoral head is an-other possible indication for RF ablation. To address thislesion with an open procedure would pose significantrisk to the articular cartilage, the growth plate, and thevascular supply to the femoral head. CT-guidance canallow for accurate placement of an introducer and abla-tion probe to treat the lesion with significantly lessmorbidity and risk.

Osteoblastoma may also be treated with RFA. Becauseosteoblastomas can usually range from 1.5 to 2 cm insize, they may need to be treated with a multi-tip array



probe to increase the treatment area to cover the wholelesion.13

POSTOPERATIVE CARE

Compared with surgical removal of a lesion, radiofre-quency ablation offers a quicker, safer return to preop-erative function. The creation of a stress riser because ofbone removal is decreased with RF ablation thereforepatients can usually weight bear as tolerated and return tonormal activities as they feel comfortable. Hospital stayis also reduced and a majority of these patients can gohome the same day because of less anesthesia time andless insult to the procedure site. Overnight admission isuncommon after this procedure but may be necessary ina select few patients with uncontrolled pain. Pain isusually greatest in the immediate postoperative periodbecause of the local necrosis but this should becomemuch more tolerable in the first 24 hours. Most patientswill be off pain relieving medications within a week ofthe procedure. Patients are seen two weeks postopera-tively to check their incision, remove sutures if used, andfor a postoperative radiograph. Patients with superficiallesion locations should especially be assessed for skinnecrosis and should be seen at a shorter initial postoper-ative follow up interval. The majority of patients treatedfor an osteoid osteoma will be pain-free at this timeinterval and completely off medication. A short-termfollow up is useful at 3 months postprocedure and then afollow up at 1 year with a new radiograph is offered tothe patient. There are no studies that have addressed thelong-term radiographic follow up of patients with anosteoid osteoma treated with RFA. Many patients willask what will happen to the lesion on the follow-upradiographs. There is no data in the literature to helpanswer this question and is an area for future research.

PEARLS AND PITFALLS● RFA is indicated for use in treating osteoid osteomas,

metastatic bone disease, and some other bone lesions.● Planning and organization are crucial to having a

successful experience.● Placement of the dispersion (grounding) pads is im-

portant to prevent heat related complications of theprocedure.

● Larger lesions may require multiple ablation cyclesand repositioning of probe for optimum results.

● Return to preoperative activity level is rapid and it isuncommon to need any restrictions on activity level.

REFERENCES

1. Barei DP, Moreau G, Scarborough MT, et al. Percutaneous radio-frequency thermal ablation of osteoid osteoma. Clin Orthop RelatRes 2000;373:115–124.

2. Callstrom MR, Charboneau JW, Goetz MP, et al. Image guidedablation of painful metastatic bone tumors: a new and effectiveapproach to a difficult problem. Skeletal Radiol 2006;35:1–15.

3. Cantwell C, Obyrne J, Eustace S, et al. Current trends in treatmentof osteoid osteoma with an emphasis on radiofrequency ablation.Eur Radiol 2004;14:607–617.

4. Finstein JL, Hosalkar HS, Ogilvie CM, et al. Case reports: anunusual complication of radiofrequency ablation treatment of os-teoid osteoma. Clin Orthop Relat Res 2006;448:248–251.

5. Goetz M, Callstrom J, Charboneau JW, et al. Percutaneous image-guided radiofrequency ablation of painful metastases involvingbone: a multicenter study. Journal of Clinical Oncology 2004;22:300–306.

6. Goldberg VM, Jacobs B. Osteoid osteoma of the hip in children.Clin Orthop 1975;106:41–47.

7. Gronemeyer DH, Schirp S, Gevargez A, et al. Image guidedradiofrequency ablation of spinal tumors; preliminary experiencewith an expandable array electrode. Cancer J 2002;8:33–39.

8. Jackson RP, Reckling FW, Mantz FA. Osteoid osteoma andosteoblastoma: similar histologic lesions with different naturalhistories. Clin Orthop 1977;128:303–313.

9. Kojima H, Tanigawa N, Kariya S, et al. Clinical assessment ofpercutaneous radiofrequency ablation for painful metastatic bonetumors. Cardiovasc Intervent Radiol 2006;29:1022–1026.

10. Lindner N, Scarborough MT, Ciccarelli JM, et al. CT-guidedradiofrequency ablation for treatment of osteoid osteoma in com-parison to traditional techniques. Z Orthop Ihre Grenzgeb 1997;135:522–527.

11. Marchal F, Brunaud L. Radiofrequency ablation in palliative sup-portive care: early clinical experience. Oncol Rep 2006;15:495–499.

12. Osti OL, Sebben R. High-frequency radio wave ablation of osteoidosteoma in the lumbar spine. Eur Spine J 1998;7:422–425.

13. Posteraro AF, Dupuy DE, Mayo-Smith WW. Radiofrequencyablation of bony metastatic disease. Clin Radiol 2004;59:803–811.

14. Rosenthal D, Hornicek F, Torriani M, et al. Osteoid osteoma:percutaneous treatment with radiofrequency energy. Radiology2003;229:171–175.

15. Rosenthal D, Springfield D, Gebhardt MC, et al. Osteoid osteoma:percutaneous radio-frequency ablation. Radiology 1995;197:451–454.

16. Rosenthal DI, Hornicek FJ, Wolfe MW, et al. Percutaneous radio-frequency coagulation of osteoid osteoma compared with operativetreatment. J Bone Joint Surg 1998;80:815–821.

17. Tins B, Cassar-Pullicino V, McCall I, et al. Radiofrequency abla-tion of chondroblastoma using a multi-tined expandable electrodesystem: initial results. Eur Radiol 2005;16:804–810.

18. Ward W, Eckardt J, Sheyestehfar S, et al. Osteiod osteoma diag-nosis and management with low morbidity. Clin Orthop Relat Res1993;291:229–235.

19. Weber K, Gebhardt M. Specialty update what’s new in musculo-skeletal oncology. J Bone Joint Surg 2003;84:761–767.

20. Woertler K, Vestring T, Boettner F, et al. Osteoid osteoma: CTguided percutaneous radiofrequency ablation and follow up in 47patients. JVIR 2001;12:717–722.



APPENDIX. Rita Medical Systems RFA protocol for treatment of osteoid osteomas.



APPENDIX. Continued.









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Use of Radiofrequency Ablation in the Treatment of Bone · PDF file · 2015-07-23Use of Radiofrequency Ablation in the Treatment of Bone Tumors ... tion zone enabling a higher rate