Tag Archives: bone tumor

Expansive unicameral bone cyst occupying the distal tibia: A case report

by Andrew Robitaille, DPM1*; Lawrence M. Fallat, DPM, FACFAS 2

The Foot and Ankle Online Journal 13 (3): 11

Unicameral bone cysts (UBC) of the distal tibia are usually incidental findings. We present a case of a 50-year-old female who initially presented with chronic bilateral heel pain. Initial radiographs revealed plantar heel spurs, but also a large intraosseous cyst in the distal right tibia. Computed tomography was obtained which showed a large, multiseptated, lucent, expansile bone lesion in the central medullary canal the distal metaphyseal-diaphyseal junction of the distal tibia. To prevent fracture of the thin cortex and stop expansion of the cyst, surgical intervention was chosen. This case report serves to show how standard x-ray revealed a large UBC that could result in fracture of the distal tibia.

Keywords: bone tumor, cyst, unicameral, tibia, benign

ISSN 1941-6806
doi: 10.3827/faoj.2020.1303.0011

1 – Resident, Submitted during Postgraduate Year 1, Beaumont Hospital, Wayne, MI, Podiatric Foot and Ankle Surgical Residency
2 – Director, Beaumont Health Wayne Podiatric Foot and Ankle Surgical Residency, Beaumont Hospital, Wayne, MI
* – Corresponding author: andrew.robitaille@beaumont.org


Unicameral bone cysts (UBC) are relatively uncommon benign bone tumors found mostly in the metaphysis of long bones, such as the humerus or femur with a male to female ratio of 3:1 [1]. UBC represents about 3% of primary tumors seen within the first two decades of life. In a meta-analysis by Kadhim, et al., in 2014, the distal tibia was only affected by UBC in 0.07% of reported cases [1]. Most of these lesions go unnoticed as they are usually asymptomatic in the absence of pathologic fracture [2]. In 1876, Virchow first described these lesions as cystic structures caused by abnormalities in local circulation [3].

Treatment goals for UBC include reestablishing bone strength, cortical thickness and elimination of the cyst [1,2]. There are various treatment modalities for UBC, which include conservative and surgical treatment [4]. Before surgical intervention, a thorough examination and clinical history must be obtained. Plain film radiography is usually sufficient for visualization and diagnosis of bone tumor [1]. Computed tomography (CT) or magnetic resonance imaging (MRI) should be obtained to evaluate the extent, size, and character of the tumor for treatment planning [2].

In this report, we present an unusual case of an adult female patient who was diagnosed on standard radiographs with an incidental finding of a large cystic lesion occupying the metaphyseal-diaphyseal region of the distal tibia. With the aid of CT, the lesion was further evaluated and then surgically treated with curettage and filled with allogenic bone chips and demineralized bone matrix (DBM).

Case Report

A 50-year-old female presented to the clinic with the chief complaint of bilateral plantar heel pain. Plain films were obtained and a large cystic lesion was noted to the patient’s right distal tibia (Figure 1). The patient denied any inciting event. Upon physical exam, there was mild dull pain at the end range of dorsiflexion to the right ankle, but was otherwise unremarkable. Computed tomography (CT) of her right ankle was obtained to further evaluate the cystic lesion.

Figure 1 Lateral and anteroposterior radiographs showing initial clinical presentation of a large expansive cystic lesion of the distal tibia.

Figure 2 Computed tomography imaging revealing a large multiseptated cyst in the metaphyseal-diaphyseal junction of the tibia with noted thinning of the medial cortex.

CT results showed a large, multiseptated, lucent, expansile bone lesion with thin medial cortex in the central medullary canal in the metaphyseal-diaphyseal junction of the distal tibia. The lesion measured 3.9 x 4.1 x 6.8 cm (Figure 2). The patient was booked for surgical excision and curettage of the right distal tibia bone cyst with insertion of allogenic bone graft, DBM, and included a biopsy.

The patient was brought into the operating room and placed on the operating room table in the supine position. General anesthesia was administered. The right lower extremity was prepped, marked and draped in the usual aseptic manner and a pneumatic thigh tourniquet was then inflated to 325mmHg.

Figure 3 A) Cortical window on the anterior distal tibia B) Cystic contents which included fatty tissue with hard and soft bone.

Figure 4 Intraoperative anteroposterior and lateral views after filling of cyst cavity with allograft and demineralized bone matrix. Also shown is the fixation of the bone window with one third tubular plate with two 3.5mm nonlocking cortical screws placed proximally and one distally.

An anterior incision 8 cm in length, just medial to the tibialis anterior tendon, was made overlying the anterior ankle which allowed direct visualization of the distal tibia. Four drill holes were made in the anterior tibia outlining the planned cortical window which measured 4 cm x 2cm. The window was cut and removed in one piece revealing the contents of the cyst which contained multiple osseous septa with both hard and soft bone (Figure 3). The entire area of the bone cyst was curetted and excised. Complete cyst excision was confirmed with fluoroscopy and direct visualization. It was noted that there was a large posterior portion of the cyst tunneling 2 cm proximally and inferiorly from the cortical window. Following intramedullary debridement, the cortex remained intact on all sides with no evidence of fracture.  All the material was removed from the cyst and was sent to pathology. The cavity of the cyst was irrigated and 89% phenol was applied to the entire bone cyst area.

Figure 5 Histological slides displaying fragments of sclerotic trabecular bone, consistent with unicameral bone cyst (original magnification 10x and 40x, hematoxylin and eosin).

Due to the large defect post-curettage, the cavity was filled with a combination of crushed allogenic bone chips and DBM. The cystic cavity was completely packed and the bone window was replaced and tamped into position. To prevent displacement of the cortical window, a 7-hole 1/3 tubular plate was placed anteriorly with a distal bend to fit the contour of the tibia. Alignment of the plate was confirmed both visually and with fluoroscopy. Following this, two 3.5 non-locking cortical screws were placed proximal, and one 3.5 non-locking cortical screw was placed distally (Figure 4). The surgical site was flushed with copious amounts of antibiotic solution and closure was completed. Following the procedure, the patient was placed in a well-padded, bivalved, below-the-knee cast and instructed to remain non-weightbearing with the use of crutches. She was prescribed hydrocodone for pain and aspirin 325 mg twice daily to be taken for deep vein thrombosis prophylaxis. The pathology specimen revealed fragments of sclerotic trabecular bone with spindle cells, most consistent with unicameral bone cyst (Figure 5).

Figure 6 Anteroposterior and lateral foot view of patient at twelve months postoperatively highlighting complete consolidation of cortical window.

The patient continued to present to the clinic on a regular basis for postoperative evaluation and serial radiographs. On the first two postoperative appointments (week 1 and 3), the patient’s visual analog pain score (VAS) was 2 out of 10. Radiographs showed incorporation of bone graft material and the patient was allowed to partial weight bear as tolerated. By the patient’s third postoperative appointment (8 weeks), the patient’s VAS score was 0 out of 10. Radiographs were taken, revealing consolidation of the cortical window in the right tibia with no recurrence of bone cyst. At this time, the patient was transitioned into normal shoe gear and sent to physical therapy with goals of decreasing edema, increasing range of motion, and increasing strength. At the patient’s one-year follow-up, radiographs were taken revealing no recurrence of bone cyst and the patient remained asymptomatic and had no limitations on full activity (Figure 6).

Discussion

Multiple theories have been postulated for the pathogenesis of unicameral bone cysts. Blockage in the venous drainage is the most favored mechanism which occurs in rapidly growing and remodeling cancellous bone [2, 3, 4]. This increased pressure may lead to the resorption of bone. Others have postulated that there could be a disturbance in bone growth, intramedullary hemorrhages secondary to trauma that do not completely resolve, degenerative phase of benign tumor, and osteomyelitis [2,10]. Cyst fluid analysis has shown increased levels of prostaglandin e2, IL1 beta, and proteolytic enzymes which could lead to bone resorption and cyst formation [5].

Treatment for UBCs is either observation or surgical intervention [2]. Reported surgical treatment includes medullary decompression with cannulated screws or intramedullary nails, steroid injections, or curettage with autograft or allograft [1, 2, 5-8]. Scaglietti, et al., were first to describe percutaneous injection of methylprednisolone acetate for UBC treatment in 1974 with only 24% healing rate after one injection [8]. Several authors have found satisfactory results with healing rates between 50-90% with steroid injections, but most reported that several procedures were necessary for cyst consolidation [1,6]. It has been reported that steroid injection may prevent the pro-inflammatory cytokine activity that leads to cyst formation as well as to relieve cyst pressure due to trepanation [1, 8].

Other injectable materials including bone graft and demineralized bone matrix (DBM) have been evaluated. Lokiec, et al., in 1996 was the first to report the use of autologous bone marrow injections for UBC treatment in children with 100% success rate [9]. Other studies have used bone marrow graft in combination with DBM [7, 11]. These studies attribute the high success rate due to bone marrow’s osteoprogenitor cells in combination with the osteoinduction and osteoconduction properties of DBM [7, 11]. Multiple authors have evaluated the effectiveness of DMB alone as an injection with high success rates [6,7]. Cho, et al., in 2012 evaluated twenty-five patients with a unicameral bone cyst who were treated with intramedullary decompression followed by grafting of demineralized bone matrix [2]. They used a small incision to create a cortical window to allow for curettage and decompression of the cyst and subsequently injection a mixture of allograft bone and DMB. Their success rate was 100% with a mean healing time of 6.6 months. Two patients required a second procedure, which they determined the initial amount of bone void filler was not enough to fill the entire space. The authors concluded that mixture of bone graft material, DBM, and completely filling the cyst was successful with satisfactory results [2].

Due to the size of our patient’s cyst, we used a longer incision and created a cortical window over the anterior distal tibia. This approach made it possible for visualization and use of curettes to completely remove all cyst material and to obtain a biopsy. This approach may appear more aggressive than other reported procedures, but because of the large size of the cyst and age of the patient, it was necessary for visualization and complete curettage, biopsy, and filling of the cyst with allograft and DBM. Similar techniques have been reported from multiple authors with healing rates greater than 90% [1, 6, 7]. The surgical curettage is necessary to resolve the cyst, but also allows for biopsy, which is necessary to rule out malignancy such as Ewing’s sarcoma and osteosarcoma because they also present as cystic lesions radiographically [5].

Unicameral bone cysts are usually incidental finding with many factors that could contribute to their formation. Although there is no standardized treatment for UBC, the goal of treatment is to prevent pathological fracture and, in children and adolescents, to prevent skeletal deformities during growth. Surgical procedures such as curettage with allogenic bone graft have been shown to be successful treatment with low rates of recurrence [1, 6, 7]. The surgical curettage is necessary to obtain tissue for biopsy to determine pathology including Ewing’s sarcoma and osteosarcoma [5]. In this report, we present a patient who was treated successfully with surgical curettage and allogenic bone graft for a distal tibia UBC with no cyst recurrence after one year. Long-term clinical follow-up is necessary for observation of potential cyst recurrence.

References

  1. Kadhim, M, Thacker, M, Kadhim, A, & Holmes, L Treatment of unicameral bone cyst: systematic review and meta-analysis. Journal of Childrens Orthopaedics 2014;8(2):171–191.
  2. Cho, HS, Seo, SH, Park, SH, Park, JH, Shin, DS, & Park, IH. Minimal invasive surgery for unicameral bone cyst using demineralized bone matrix: a case series. BMC Musculoskelet Disord 2012;13:124.
  3. Virchow R. On the formation of bony cysts, in Uber die Bildung von Knochencysten. In SB Akad Wiss, 1876; pp 369–381, Berlin.
  4. Noordin, S, Allana, S, Umer, M, Jamil, M, Hilal, K, & Uddin, N. Unicameral bone cysts: Current concepts. Annals of Medicine and Surgery, 2018;34: 43–49.
  5. Cohen J. Unicameral bone cysts. A current synthesis of reported cases. Orthop Clin North Am 1977;8:715–736.
  6. Kanellopoulos AD, Mavrogenis AF, Papagelopoulos PJ, Soucacos PN. Elastic intramedullary nailing and DBM-bone marrow injection for the treatment of simple bone cysts. World Journal of Surgical Oncology 2007;5, 1:111.
  7. Rougraff BT, Kling TJ. Treatment of active unicameral bone cysts with percutaneous injection of demineralized bone matrix and autogenous bone marrow. J Bone Jt Surg Am 2002;84-A 6:921–929.
  8. Scaglietti O, Marchetti PG, Bartolozzi P. Final results obtained in the treatment of bone cysts with methylprednisolone acetate (depo-medrol) and a discussion of results achieved in other bone lesions. Clin Orthop Relat 1982;165:33‐42.
  9. Lokiec F, Ezra E, Khermosh O, Wientroub S: Simple bone cysts treated by percutaneous autologous marrow grafting. A preliminary report. J Bone Joint Surg 1996;78: 934-937.
  10. Rosario, MS, Yamamoto, N, Hayashi, K, Takeuchi, A, Kimura, H, Miwa, S, Tsuchiya, H. An unusual case of proximal humeral simple bone cyst in an adult from secondary cystic change. World Journal of Surgical Oncology 2017;15:102.
  11. Di Bella C, Dozza B, Frisoni T, Cevolani L, Donati D. Injection of demineralized bone matrix with bone marrow concentrate improves healing in unicameral bone cyst. Clin Orthop Relat 2010;468: 3047-3055.

Desmoplastic fibroma of bone: Case report and review of the literature

by Zachary M. Thomas, DPM, AACFAS,CWSP1,  Matthew J. Sabo, DPM, FACFAS2pdflrg

The Foot and Ankle Online Journal 8 (2): 3

This is a case report on an unusual presentation of desmoplastic fibroma of bone. We feel that this presentation should be documented and reviewed in comparison to the available literature, as this tumor is seldom documented in the foot. We review the differential diagnosis, pertinent imagine findings, and surgical management of this pathology.

Key words: desmoplastic fibroma, benign tumor, bone tumor

ISSN 1941-6806
doi: 10.3827/faoj.2015.0802.0003

Corresponding author: Zachary Thomas, DPM
zachthomasdpm@gmail.com

1 Academy of Podiatry, Pittsburgh, PA
2 Foot and Ankle Wellness Center of Western Pennsylvania, Ford City, PA


Desmoplastic fibroma of bone is a benign, locally aggressive tumor with varied recurrence rates found in the literature. Desmoplastic fibroma of bone, when found in the foot, is an exceedingly rare occurrence [1]. Jaffe first described it as a benign tumor characterized by the formation of abundant collagen fibers by the tumor cells. The tissue is described as being poorly cellular with nuclei that are ovoid or elongated. The incidence of whole-body desmoplastic fibroma is less than 0.1% [1,2]. The most common presenting symptom is pain and/or swelling, although pathologic fracture has been described previously as a common reason for seeking treatment. This tumor has also presented as an incidental finding [2]. The most common differential diagnosis radiographically is fibrosarcoma, however a wide variety of entities can masquerade as a desmoplastic fibroma including fibrous dysplasia, giant cell tumor, unicameral bone cyst, chondromyxoid fibroma, nonossifying fibroma, periosteal desmoids, eosinophilic granuloma, low-grade intraosseous osteosarcoma, adamantinoma, as well as distant metastasis [1-4].

This tumor has been described in patients ranging from 15 months to 75 years of age, and it is most commonly seen in the mandible, femur, pelvis, radius, and tibia [4].

Roentgenograms typically reveal an oval, long axis oriented lytic, expansile lesion with a lucent matrix. The cortex of the involved bone appears thinned and may be violated in more advanced cases [2-4] (Figures 1,2). MRI features include inhomogeneous low signal intensity on T1 weighted images and mixed signal intensity on T2 weighted images. Post-contrast T1 images show irregular, non-enhancing areas incased within an enhanced mass. The areas of low signal intensity on T2 and post-contrast T1 correlate with abundant collagen fibers. The high signal intensity areas on T2 and post-contrast T1 were correlated with fibroblasts and loose collagen fibers [5,6].

Case Report

A 75-year-old male patient presents with the complaint of pain in the first metatarsal region. He states he had been having pain, which has been getting progressively worse for the past several months. On physical exam, there was edema in the right first ray region extending to the proximal foot and into the right leg.  There was exquisite pain to palpation dorsally along the entire course of the first metatarsal.

fig1

Figure 1 Lateral Pre-op x-ray of desmoplastic fibroma.

fig2

Figure 2 AP/MO standard radiographic views pre-operatively.

fig3

Figure 3 Intraoperative view of resected tumor through cortical window.

A visible deformity and limited, painful range of motion of the 1st MTPJ was noted. Clinical examination was consistent with hallux abductovalgus with associated dorsal exostosis. Radiographs displayed an expansile, lytic lesion at the distal diaphysis extending in to the metaphysis/epiphysis. MRI showed a small cortical break in the distal segment of the lesion. Our main concern at the time of discovery was aggressiveness of this lesion. Bone scan and chest x-ray revealed no other lesions in the body. At this point, biopsy was elected to determine the nature and aggressiveness of the lesion.

Intraoperatively, a linear incision was made along the first metatarsal and deepened to the deep fascial layer where a capsular-periosteal incision was made. There was gross deformity of the first metatarsal head as well as deformity extending to the midshaft of the aforementioned bone. The specimen measured 1.5 cm X 1.2 cm X 0.3 cm. The most proximal aspect of the first metatarsal base was the only unaffected portion of the bone. The mass was removed by excising a rectangular window with the tumor housed inside. The tumor was very soft and, upon removal, it was made certain to excise normal margins on all sides of the tumor (Figure 3).  The mass was sent to the pathologist intraoperatively where it was confirmed a benign mass. At this point, the remaining void was curetted to ensure adequate removal of tumor, flushed, and finally packed with a mixture of putty and cancellous bone chips. The dorsal cortical window was replaced and the wound was closed in layers. The pathology report returned with the diagnosis of desmoplastic fibroma. The characteristics of this particular tumor were a bland spindle cell appearance and lack of woven bone formation. The lesion was, however, negative for beta-catenin.

At 14 days post-operatively, the patient’s incision site was well coapted and sutures were removed. At 4 months post-operatively, the patient’s graft site was fully consolidated, and at 10 months post-operatively the patient was walking with no pain. Radiographs did not display any signs of recurrence (Figures 4,5,6).  At 22 months, the patient has not experienced any recurrent symptoms and radiographs have not shown any recurrence.

fig4

Figure 4 Radiographs at 2 weeks post-operatively.

fig5

Figure 5 Radiographs 10 months post-operative showing consolidation.

fig6

Figure 6 Radiographs 10 months post-operative showing consolidation.

Discussion

Desmoplastic fibroma of bone, although considered benign, can be a debilitating condition leading to loss of limb [1-7]. Pathologic elements of this tumor include fibroblasts, collagen fibers, and elongated nuclei. These tumors begin inside the medullary canal and expand outward at which time it is possible to breach the cortex and invade adjacent tissues [3]. There have been isolated reports of associated osseous sarcomas arising in the areas of these tumors [4-8]. Bohm et al found a 50% recurrence rate with 25% of those leading to amputation in the extremities. The treatment of choice when confronted with this clinical and x-ray picture is bone biopsy, wide excision, and bone grafting [3,7].  Recurrent lesions can lead to selective amputation. Considering this bone tumor’s relative infrequency, we hope this case report provides guidance in treatment for the foot and ankle surgeon who may be confronted with this entity.

References

  1. Min H, Kang H, Lee J, Lee G, Ro J. Desmoplastic Fibroma with malignant transformation.Annals of Diagnostic Pathology 2010 Feb;14(1): 50-55. Pubmed
  2. Inwards C, Unni K, Beabout J, Sim F. Desmoplastic Fibroma of Bone.Cancer 1991 Nov;68(9):1978-1983. Pubmed
  3. Beskin J, Haddad R. Desmoplastic Fibroma of the First Metatarsal A Case Report.Clinical Orthopaedics and Related Research 1985 May;195:299-303. Pubmed
  4. Bohm P, Krober S , Greschnoik A, Laniado M, Kaiserling E. Demoplastic Fibroma of the Bone.Cancer 1996 Sep;78(5):1011-1023. Pubmed
  5. Shuto R, Kiyosue H, Yuko H, Miyake H, Kawano K, Mori H. CT and MR imaging of desmoplastic fibroblastoma.European Radiology 2002 Oct;12(10):2474-2476. Pubmed
  6. Evans, H. Demoplastic Fibroblastoma A report of Seven Cases.American Journal of Surgical Pathology 1995 Sep;19(9):1077-1081. Pubmed
  7. Takazawa K, Tsuchiya H, Yamamoto N, Nonomura A, Suzuki M, Taki J, Tomita K. Osteosarcoma arising from desmoplastic fibroma treated 16 years earlier: a case report. J Orthop Sci 2003;8(6):864-8. Pubmed
  8. Kim OH, Kim SJ, Kim JY, Ryu JH, Choo HJ, Lee SJ, Lee IS, Suh KJ.  Desmoplastic fibroma of bone in a toe: radiographic and MRI findings. Korean J Radiol. 2013 Nov-Dec;14(6):963-7. Pubmed

Calcaneal Intraosseous Lipoma treated with External Fixation: A case report and review of the literature

by James Losito, DPM1, Victor L. Herrera, DPM2, Riquel Gonzalez, DPM3, Thomas Merrill, DPM4

The Foot and Ankle Online Journal 5 (8): 1

A case report is presented of an intraosseous lipoma. Diagnosis was made with the help of Magnetic Resonance Imaging and histopathologic analysis, after which the patient was treated by means of curettage and packing with bone graft substitute. Surgical, histologic features and a staging classification for intraosseous lipoma are presented in this case report. This article also discusses the use of external fixation in a patient with high risk of calcaneal fracture and to promote early weight bearing and early recovery. Although calcaneal intraosseous lipoma accounts for a small portion of cases in the huge differential diagnosis chart for foot pain such as plantar fasciitis, retrocalcaneal bursitis, gout and stress fracture, it should be kept in mind as a possible diagnosis in cases of unresolved pain to the heel.

Key Words: Intraosseous lipoma, external fixation, heel pain, bone tumor.

Accepted: July, 2012

Published: August, 2012

ISSN 1941-6806
doi: 10.3827/faoj.2012.0508.0001


Intraosseous lipomas are rare benign bone tumors. This benign neoplasm has been reported to occur in the calcaneus as well as the proximal femur [1,6,7]. In the past, the relative absence of symptoms and radiographic similarity to a bone cyst has accounted for under diagnosis of intraosseous lipoma [2,3]. Intraosseous lipomas are derived from mature lipocytes mostly seen at the metaphysis of the long bones in men [5,6]. Foot and heel pain are the common symptoms of calcaneal intraosseous lipoma [5].

Non-surgical options such as NSAIDs, cold compression, use of non-weight bearing devices such as cane, use of silicone sole plate and preventive measures for pathological fractures are the most commonly used treatment modalities for this condition. Surgery is indicated in the presence of pain resistant to conservative treatment methods, impending or pathological fractures and when a histopathological differential diagnosis is required for aneurismal bone cyst, giant cell tumor, pseudo cyst formation or unicameral bone cyst. Although surgical treatment with curettage and autogenous bone grafting has been reported as a treatment choice, only small case series have been reported thus far [10]. In this study, we present one calcaneal intraosseous lipoma in a patient treated with curettage, autogenous bone grafting and Ilizarov external fixator.

Case Report

A 23 year-old male presents with the complaint of a dull, aching pain in his right heel of 2 years of duration. The pain was noted to increase after strenuous walking, long time of standing or other rigorous activities involving the right foot. The pain has been increasing steadily over the 3-4 months period. Patient stated the pain is persistent and worse at the end of the day. The pain is ranked (7 out of 10) on pain scale with 0 no pain, and 10 severe pain. There is associated swelling observed of the right foot.

 

Figures 1A and 1B Lateral plain x-rays (A) and antero-posterior views (B) with well-circumscribed bone lesion.

On gross examination, the patient walked with an antalgic gait. There is a small soft tissue palpable fluent mass on the right medial arch below the medial malleolus compatible with a possible superficial soft tissue lipoma. No scars, sinuses or venous prominences overlying the affected area, and the right ankle and subtalar joint motions were normal.

There is pain on palpation to the right heel and ankle. There is no past medical history that would increase the likelihood of bone infarction, such as corticosteroid use, infection, previous irradiation, lipid storage disease, collagen-vascular disease, or lympho-proliferative disorder.

Diagnosis

Plain radiographs revealed the presence of a well-circumscribed radio-mixed lesion with a thin sclerotic rim, interspersed with trabeculations in the antero-inferior portion of the left calcaneus underlying the subtalar joint. (Figs.1A and 1B) A preoperative magnetic resonance imaging (MRI) scan of the Right foot reveals the presence of a 2.3 x 2.0 cm circumscribed mass to the neck and body of the calcaneus. Predominant fat signal is seen on all pulse sequences. There is an eccentric component of fluid signal within the lateral aspect of the mass (Figs. 2A, 2B, 2C and 2D). The appearance of the mass is compatible with an intraosseous lipoma. There is prominent fatty tissue seen in the plantar, medial aspect of the right hindfoot most likely represents a prominent lobule of subcutaneous fat. It is at this point that the surgical option was discuses with the patient and he agreed to undergo surgical approach of his condition.

   

Figures 2A, 2B, 2C and 2D T1/T2 sagittal images shows fluid signal within the lateral aspect of the mass. (A and B) T1/T2 coronal images with well demarcated mass in the calcaneus. (C and D)

Surgical Approach

Based on the clinical and diagnostic image findings, intraosseous lipoma is diagnosed and operative decompression of the cyst is subsequently undertaken. Prior to the operation, the lesion is localized fluoroscopically and its localization is marked on the skin. Under tourniquet control, a straight lateral skin incision is performed over the lesion and the periosteum is incised longitudinally. The lesion and a portion of the adjacent normal tissue were exposed at one end of the lesion using a 1cm×1 cm rectangular cortical window. The cortex overlying the cyst is exposed on the inferior and lateral aspects. Using an oscillating saw and osteotome the cortex is opened and the lesion is totally curetted out with angled curettes through the cortical window.

As the cyst is decorticated, a greasy-yellow intraosseous lipoma is identified and evacuated from the osseous cavity. The soft tissue contents of the intraosseous cyst were removed along with the greasy fluid and the entire specimen is sent for histopathologic diagnosis. The cavity of the calcaneus is lavaged with normal saline before cancellous allograft bone is used to pack the cavity. After filling the cavity, the wound is closed in anatomic layers and a sterile dressing applied, followed by application of an Ilizarov ring external fixator for the initial postoperative period to allow for weight-bearing ambulation (Figs. 3A and 3B). Postoperative radiographs show the orientation of the external fixator to allow for early amputation after surgery (Figs. 4A and 4B).

 

Figures 3A and 3B Ring External Fixation system applied after the excised the bone tumor.

 

Figures 4A and 4B Lateral and A-P views of Post-Op X-Rays evaluation.

Subsequent histopathologic analysis reveals fragments of bone which include a few fragments of necrotic bone and fibroadipose tissue which shows foci of fat necrosis and necrosis of other soft tissue-types. The morphology suggests a possible fracture site or tendon avulsion. There is no evidence of neoplasm. These findings are consistent with the diagnosis of intraosseous lipoma. The patient’s heel pain subsided almost immediately after the operation, with the exception of surgical wound pain, which subsided in normal fashion.

A postoperative magnetic resonance imaging (MRI) scan of the right] foot is done 3 months after surgery once the fixator is removed. This reveals the resection of the previously described intra-osseous fatty mass in the neck and body of the calcaneus. Intermediate signal intensity tissue now fills this region of the calcaneus. There is no calcaneal fracture identified (Figs. 5A, 5B, 5C and 5D).

   

Figures 5A, 5B, 5C and 5D MRI shows T1/T2 sagittal views. (A and B) T1/T2 axial views of 12weeks MRI follow up evaluation shows bone graft uptake and reduced size of the bone cavity without fluid signal. (C and D)

Two weeks following suture removal, the patient is mobilized with instructions for partial weight bearing in the following 3 weeks, followed thereafter by weight bearing as tolerated. Clinical and radiological examinations are performed on the first postoperative day, at 6weeks, at 12weeks and every other month thereafter, until there is radiological confirmation of graft consolidation (Figs. 6A, 6B, 6C and 6D).

   

Figures 6A, 6B, 6C and 6D Clinical examinations at 12weeks post-op, without External Fixation. There is now good and adequate ankle range of motion.

Discussion

Milgram’s classification system is used for staging the lesions: In stage 1, the lesion is a solid lipoma composed of viable fat cells; in stage 2, part of the lesion is necrotized, forming focal calcification; and in stage 3, most of the tumor tissue has died, with variable degrees of cyst formation, calcification, and reactive new bone formation [19].

Histopathologic analysis of our (specimen) reveals fragments of bone which include a few fragments of necrotic bone and fibroadipose tissue showing foci of fat necrosis and necrosis of other soft tissue-types. The morphology suggests a possible fracture site or tendon avulsion. There is no evidence of neoplasm. These findings were consistent with the diagnosis of stage 2 intraosseous l intraosseous.

The need for surgical treatment is controversial. Curettage with bone grafting is the treatment of choice when surgical intervention is needed. Most lipomas, however, can be managed conservatively. Some surgeons feel that in asymptomatic cases with no signs of an impending pathologic fracture or suspicion of malignancy that a non-operative treatment with clinical and radiological follow-up is indicated. Malignant transformation is rare. While some surgeons think that biopsy is unnecessary because radiological features are characteristic, others believe that the lesion must be diagnosed histologically. However, reports stating that biopsy is required usually predate the common and efficient use of MRI, when an accurate radiological diagnosis was almost impossible.

We believe that pain alone is not an indication for surgical intervention or any other invasive treatment, including biopsy. The cause of pain in the patient with intraosseous lipomas is unclear, but it may be mechanical due to expansile remodeling of bone. It may be related to the ischemic changes that frequently accompany these lesions. It is also possible that the pain is referable from nearby joint disease and that the an intraosseous lesion is incidentally discovered. It is reported that symptoms may recur after surgical treatment or resolve spontaneously on conservative treatment, thus suggesting that many intraosseous lipomas are incidental findings and that patients may have another, unidentified cause of symptoms. Microtrabecular fracture in areas of weakened bone following episodes of minor trauma may be one cause of pain. Areas of diffuse increased signal were observed on MRI within the lipoma in some series, which may represent a stress response.

Asymptomatic intraosseous lipomas of the calcaneus should not require surgical intervention, since the tumor always occurred in the region of Ward’s triangle, which is a non weight-bearing region. In fact, in healthy individuals it is a region with bone paucity. A pathological fracture seems to be unlikely and has not been previously reported in the calcaneus.

Small cysts that are not located in the pressure-bearing trabecular area of the calcaneus are usually asymptomatic and can be treated conservatively. A “critical-size cyst” has been defined as an intraosseous lipoma extending the full breadth of the calcaneus laterally to medially in the coronal plane, and occupying at least 30% of the length of the calcaneus anteroposterior. Since the presence of a pathological fracture through a calcaneal cyst makes the operative procedure more complex and healing less predictable, the authors believe that large symptomatic calcaneal cysts should be managed surgically to reduce morbidity.

The decision to operate on a calcaneal cyst should be based on its size and location, the provisional diagnosis, associated symptoms, and the activity level and health of the patient. Although intraosseous lipoma is a benign lesion, Milgram [19] described four cases of intraosseous lipoma that underwent malignant transformation. Liposarcoma and malignant fibrous histiocytoma have also been found adjacent to benign lipomas.

Treatment of intraosseous lipomas is still controversial. Hirata, et al.[30], suggested that surgical treatment is not necessary owing to the potential for spontaneous regression and very low rate of malignant transformation. However, according to Weinfeld, et al.[21], curettage and grafting is the best choice of treatment. Schneider stated that the need for surgical treatment relies on the risk of malignant transformation [23]. Bertram reported a 33% rate of accidental diagnosis among 54 patients and surgery was only required when the patient was clinically symptomatic [24].

Gonzalez’s conclusion was similar to Bertram and stated that the majority of calcaneal intraosseous lipomas are seen in Ward’s triangle [10]. According to Mollin, et al.[28], curettage and grafting is a good choice for permanent treatment and can be performed if the patient is symptomatic. In the present case report, we operated on a symptomatic patient. He was resistant to conservative treatment for the previous 3 to 6 months. He underwent surgery due to the pain, incapacity to perform any sport activity and a suspicion for risk of pathological fracture due to his athletic ability.

Our patient started weight bearing just after surgery with an external fixator. He recovered with full benefit after nine months, and increased his sport activities without any complaint. Since intraosseous lipoma is an uncommon bone tumor, there is a need to familiarize physicians with the radiographic and MRI features of this lesion for the correct diagnosis and treatment.

References

1.  Kapukaya A, Subasi M, Dabak N, Ozkul E. Osseous lipoma: eleven new cases and review of the literature. Acta Orthop Belg 2006 72: 603-614. [PubMed]
2.  Radl R, Leithner A, Machacek F, Cetin E, Koehler W, Koppany B, Dominkus M, Windhager R. Intraosseous lipoma: retrospective analysis of 29 patients. Int Orthop 2004 28: 374-378. [PubMed]
3.  Campbell RS, Grainger AJ, Mangham DC, Beggs I, Teh J, Davies AM. Intraosseous lipoma: report of 35 new cases and a review of the literature. Skeletal Radiol 2003 32: 209-222. [PubMed]
4.  Reig-Boix V, Guinot-Tormo J, Risent-Martinez F, Aparisi-Rodriguez F, Ferrer-Jimenez R. Computed tomography of intraosseous lipoma of os calcis. Clin Orthop Relat Res 1987 (221): 286-291. [PubMed]
5.  Yildiz HY, Altinok D, Saglik Y. Bilateral calcaneal intraosseous lipoma: a case report. Foot Ankle Int 2002 23: 60-63.  [PubMed]
6.  Buckley SL, Burkus JK. Intraosseous lipoma of the ilium. A case report. Clin Orthop Relat Res 1988 (228): 297-301. [PubMed]
7.  Arslan G, Karaali K, Cubuk M, Senol U, Lüleci E. Intraosseous lipoma of the frontal bone. A case report. Acta Radiol  2000 41: 320-321. [PubMed]
8.  Kapukaya A, Subasi M, Dabak N, Ozkul E. Osseous lipoma: eleven new cases and review of the literature. Acta Orthop Belg 2006 72: 603-614. [PubMed]
9.  Chow LT, Lee KC. Intraosseous lipoma. A clinicopathologic study of nine cases. Am J Surg Pathol 1992 16: 401-410. [PubMed]
10.  Gonzalez JV, Stuck RM, Streit N. Intraosseous lipoma of the calcaneus: a clinicopathologic study of three cases. J Foot Ankle Surg 1997 36: 306-310. [PubMed]
11.  Propeck T, Bullard MA, Lin J, Doi K, Martel W. Radiologic-pathologic correlation of intraosseous lipomas. AJR Am J Roentgenol2000 175: 673-678.  [PubMed]
12.  Kamekura S, Nakamura K, Oda H, Inokuchi K, Iijima T, Ishida T. Involuted intraosseous lipoma of the sacrum showing high signal intensity on T1-weighted magnetic resonance imaging (MRI). J Orthop Sci 2001 6:183-186. [PubMed]
13.  Levin MF, Vellet AD, Munk PL, McLean CA. Intraosseous lipoma of the distal femur: MRI appearance. Skeletal Radiol 1996 25: 82-84.  [PubMed]
14.  Blacksin MF, Ende N, Benevenia J. Magnetic resonance imaging of intraosseous lipomas: a radiologic-pathologic correlation. Skeletal Radiol1995 24: 37-41. [PubMed]
15.  Rosenblatt EM, Mollin J, Abdelwahab IF. Bilateral calcaneal intraosseous lipomas: a case report. Mt Sinai J Med 1990
57: 174-176. [PubMed]
16.  Ketyer S, Brownstein S, Cholankeril  J.  CT diagnosis of intraosseous lipoma of the calcaneus. J Comput Assist Tomogr 1983 7: 546-547. [PubMed]
17.  Kozlowski K, Welshman R. What is it? Intraosseous lipoma in a 13-year-old boy. Br J Radiol 1991 64: 855-856. [PubMed]
18.  Lagier R. Case report 128. Skeletal Radiol 1980 5: 267-269, 1980. [PubMed]
19.  Milgram JW. Intraosseous lipomas. A clinicopathologic study of 66 cases. Clin Orthop 1988 231: 277-230. [PubMed]
20.  Poussa M, Holmstrom T. Intraosseous lipoma of the calcaneus. Report of a case and a short review of the literature.  Acta Orthop Scand 1976 47: 570-574. [PubMed]
21.  Weinfeld GD, Yu GV, Good JJ. Intraosseous lipoma of the calcaneus: a review and report of four cases. J Foot Ankle Surg 2002 41: 398-411.  [PubMed]
22.  Schneider O, Mischo J, Puschel W. Intraosseous lipoma of the calcaneus. Chirurg 1994 65: 74-76. [PubMed]
23.  Bertram C, Popken F and Rutt J. Intraosseous lipoma of the calcaneus. Congen Arch Surg 2001 386: 313-317. [PubMed]
24.  Langenbecks, Tejero A, Arenas AJ and Sola R. Bilateral intraosseous lipoma of the calcaneus. A case report. Acta Orthop Belg 1999 65: 525-527.  [PubMed]
25.  Rosenblatt EM, Mollin J and Abdelwahab IF. Bilateral calcaneal intraosseous lipomas: a case report. Mt Sinai J Med 1990 57: 174-176.  [PubMed]
26.  Ramos A, Castello J, Sartoris DJ, Greenway GD, Resnick D, Haghighi P. Osseous  lipoma: CT appearance. Radiology  1985 157: 615-619. [PubMed]
27.  Bruni L. The “cockade” image: a diagnostic sign of calcaneum intraosseous lipoma. Rays 1986 11: 51-54.  [PubMed]
28.  Reig-Boix V, Guinot-Tormo J, Risent-Martinez F, Aparisi-Rodriguez F, Ferrer-Jimenez R. Computed tomography  of intraosseous lipoma of os calcis. Clin Orthop 1987 221:286-291. [PubMed]
29.  Hirata M, Kusuzaki K and Hirasawa Y. Eleven cases of intraosseous lipoma of the calcaneus. Anticancer Res 2001 21:  4099-4103. [PubMed]


Address correspondence to: Victor Herrera, DPM email: herreragioco@bellsouth.net

1Diplomate, American Board of Podiatric Surgery, American Academy Podiatric Sports Medicine.
2Senior Resident at Barry University/ Mercy Hospital, Miami, Florida
3Resident at Barry University/ Mercy Hospital, Miami, Florida
4Diplomate, American Board of Podiatric Surgery.

© The Foot and Ankle Online Journal, 2012

Percutaneous Radiofrequency Ablation through a Subtalar Approach in Osteoid Osteoma of the Calcaneus

by Ramos-Pascua L.R.,Ph.D , Santos-Martín G., MD , Fernández-Hernández O., MD , Sántos-Sánchez J.A., Ph.D , Sánchez-Herráez S., PhD 

The occurrence of osteoid osteomas of the foot is rare and their treatment has usually been surgical. A 13 year-old male with a subchondral osteoid osteoma in the right calcaneus was treated with percutaneous radiofrequency ablation using a simple subtalar approach. Two years later there was no evidence of recurrence and he remains free of pain with normal function.

The Foot and Ankle Online Journal 4 (5): 2

Key words: Osteoid Osteoma, calcaneus, bone tumor.

Accepted: April, 2011
Published: May, 2011

ISSN 1941-6806
doi: 10.3827/faoj.2011.0405.0002


Osteoid osteoma is a small benign osteoblastic tumor which causes localized pain. It accounts for approximately 11% of all benign bone tumors. It usually occurs in children and young adults and most commonly in the cortex of the shaft of long bones. Its treatment has been indicated to lighten the symptomatology and to avoid the possibility of disorders in the nearby growth cartilage, chronic changes of bone remodeling and osteoarthritis, according to the case.

The therapeutic methods of an osteoid osteoma currently available include medical treatment, bloody approach with intralesional or wide resection of the nidus, and percutaneous techniques. [1] These can be divided into two groups: those that try to remove the lesion physically (by curettage or milling). [2-4] and those that seek their destruction in-situ (ablation). The ablative techniques include the injection of ethanol, laser photocoagulation5 and radiofrequency. [6-8]

The percutaneous procedures eliminate selectively the pathologic tumoral tissue, reducing the pathological fractures morbidity and its prevention. They are technically simple, provide immediate analgesia [2-3] and add the advantage of a lower cost to the health system. In addition, they allow the use of the computerized tomography (CT) scan to exactly locate the nidus and can be done with local anesthesia, even on an outpatient basis, allowing immediate loading without any external support and a quick return to their occupations. [2]

All of these advantages are more evident in those cases located in poorly accessible areas, which would need wide and difficult approaches. The main disadvantage is the lack of histological confirmation in almost half of the cases. [1] Calcaneal osteoid osteoma is extremely rare and it has usually been treated by surgical excision. Percutaneous radiofrequency ablation (RF) in the calcaneus has been previously described as being exceptional. [9]

Case Report

A 13 year-old male presented with an 18-month history of pain and swelling in the right hindfoot and ankle. There was no history of trauma. Initially, the pain was intermittent in the morning. In the final six months, the pain became constant and more severe at night. It was relieved by Ibuprofen.

On examination, there was tenderness and swelling around the lateral aspect of the hindfoot. No erythema or heat was present. He showed full range of motion of the ankle joint and mild stiffness of the subtalar joint, with mild discomfort at the end of the range of motion.

The right calf muscles were atrophied compared with those of the left calf. There were no neurovascular deficits. Laboratory data were normal.

Plain radiographs of the ankle showed a sclerotic area in the calcaneus just below to the subtalar joint. (Fig. 1) Radionuclide bone scan revealed a focal uptake in this area. A magnetic resonance image (MRI) showed a well-circumscribed area of low-signal intensity in the anterolateral aspect of the right calcaneus adjacent to the posterior talocalcaneal joint with surrounding edema.(Fig. 2) CT scan confirmed the presence of a small osteolytic lesion with a sclerotic rim in the same place. (Fig. 3) An osteoid osteoma was diagnosed using these data.

Figure 1 Lateral radiograph of the right foot showing sclerosis at the subchondral area of the calcaneus.

Figure 2 Sagittal T1-weighted MRI shows the nidus as a well-circumscribed area of low-signal intensity in the calcaneus with bone sclerosis and edema in the surrounding bone medulla.

Figure 3 Coronal CT shows the nidus adjacent to the subtalar joint.

After a regional anesthetic, the patient was placed on the CT imaging table in a supine position with internal rotation of the leg. (Fig. 4) Under CT guidance, a Kirschner wire with an outer diameter of 1.5 mm was placed in the center of the lesion using a lateral subtalar approach. (Fig. 5) A cannula was placed over the wire; and the wire was replaced through the cannula by a TEW-STC straight electrode (Radionics™, Burlington, Massachusetts).

Figure 4 Appearance of the foot, with internal rotation of the leg. The entrance point for the thermoablation has been marked.

Figure 5 CT showing the radio-frequency electrode through the cannula in the center of the nidus.

The electrode, insulated throughout the length except for the terminal 5 mm, was heated to 90ºC for 6 minutes with a radiofrequency generator (Radionics RFG-3CF). Since the diameter of the nidus was estimated in 12 mm in length, and the thermoablation occurs only in a sphere of tissue approximately 1 cm in diameter, the procedure was repeated changing the electrode a few millimetres to one side. Finally, the electrode and the cannula were removed and the small skin wound was closed with a steristrip. A specimen was not obtained for histology.

Without postoperative complications, the patient showed an immediate relief of pain. He was allowed to bear weight immediately after the procedure and he was completely free of pain by the fourth day. At a two year follow-up, there was no evidence of recurrence and the patient remained free of pain with normal activity.

Discussion

Osteoid osteomas in the foot are rare: 4-8%. [10] Most of them are located in the hindfoot, with 30% to 60% occurring in the talus, and 2% to 3% in the calcaneus. Calcaneal osteoid osteoma has not been described in literature very often, usually as case reports in juxta-articular location. [9-15]

The juxta-articular subchondral location in the calcaneus could explain subtalar arthritis and mistaken or delayed diagnosis. [13,15-17] Finally, a long delay in treatment may lead to muscle atrophies, growth disturbances, persistent joint stiffness or contractures. [12-13] Thinking of the osteoid osteoma in a patient with a typical history of nocturnal pain relieved by NSAID medication, plus the imaging appearance of our case (although different from those of the more common cortical lesions) would be enough for the diagnosis. [18] Although not all authors are of the same opinion [19], we think that the biopsy is not necessary if there are no clinical or imaging doubts.

Even though there are cases of spontaneous healing after years of medical treatment with NSAIDs, surgical removal of the nidus is preferred to achieve rapid symptom relief.

However, the nidus is difficult to identify intraoperatively [20], requiring an excessive amount of bone resection, which may result in weakening of the bony structure and an increased risk of fracture. Moreover, when osteoid osteoma is juxta-articular in location, as in our case, articular surface can be damaged by surgery. Most calcaneal osteoid osteomas reported in literature have been treated with en-bloc resection or curettage, usually packing the calcaneal defect with cancellous bone graft or hydroxyapatite. [11-16,21] A short leg cast was always applied for some weeks postoperatively.

Percutaneous radiofrequency ablation (RF) is an alternative treatment to surgical excision in osteoid osteoma. The technique was introduced by Rosenthal, et al., [7] in 1992, and it is at present recommended as the treatment of choice in most cases. [22-23] The procedure causes thermal necrosis of a spherical area approximately 1 cm in diameter. For bigger lesions or when electrode placement is such that the entire tumor is not encompassed within one treatment, a second overlapping treatment can be given in the same session. [23] It has a primary clinical success rates of between 73% to 95% with minimal complications, usually skin injuries, and reduced use of healthcare resources. [7,24-25]

To the best of our knowledge, isolated cases involving the foot have been previously reported [26-27] and there are only a few specific reports on RF in osteoid osteoma of the calcaneus. [9,25]

Percutaneous radiofrequency ablation requires a small osseous access to allow insertion of the electrode. There is no bone loss and does not cause any significant structural weakening. This is particularly useful in calcaneal lesions, where the effects of the traditional surgery with an easy lateral subtalar approach could be avoided.

Conclusion

Percutaneous radiofrequency ablation of the nidus in osteoid osteomas has recently been introduced and offers advantages as compared with traditional open resection. In the calcaneus, the procedure could be performed on an outpatient basis and the patients can immediately resume all daily activities without cast, splints or other external supports. A larger series of calcaneal osteoid osteomas treated with radiofrequency ablation would be necessary to determine safety and efficacy.

References

1. Campanacci M, Ruggieri P, Gasbarrini A, Ferraro A, Campanacci L. Osteoid osteoma. Direct visual identification and intralesional excision of the nidus with minimal removal of bone. JBJS 81B:814-820, 1999.
2. Bühler M, Binkert C, Exner GU. Osteoid osteoma: technique of computed tomography-controlled percutaneous resection using standard equipment available in most orthopaedic operating rooms. Arch Orthop Trauma Surg 121:458-461, 2001.
3. Bühler M, Exner GU, Hodler J. CT-assisted percutaneous removal of an osteoid osteoma. Orthop Traumatol 3:159-65, 2001.
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5. Cool P, Williams DH, Pullicino V. Interstitial laser photocoagulation for the treatment of osteoid osteoma. JBJS 83B: 1125-1128, 2001.
6. Tillotson CL, Rosenberg AR, Rosenthal DI. Controlled thermal injury of bone. Report of a percutaneous technique using radiofrequency electrode and generator. Invest Radiol 24: 888-892, 1989.
7. Rosenthal DI, Alexander A, Rosenberg AE, Springfield D. Ablation of osteoid osteomas with a percutaneously placed electrode: a new procedure. Radiology 183: 29-33, 1992.
8. Lindner NJ, Ozaki T, Roedl R, Gosheger G, Winkelmann W, Wörtler K. Percutaneous radiofrequency ablation in osteoid osteoma. JBJS 83B: 391-396, 2001.
9. Migues A, Velan O, Solari G, Pace G, Slullitel G, Santini E. Osteoid osteoma of the calcaneus: percutaneous radiofrequency ablation. J Foot Ankle Surg 44: 469-472, 2005.
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19. Rosenthal DI, Hornicek FJ, Torriani M, Gebhardt MC, Mankin, HJ. Osteoid osteoma: percutaneous treatment with radiofrequency energy. Radiology 229: 171-175, 2003.
20. Rossi T, Levitsky K. Osteoid osteoma of the calcaneus: an unusual cause of hindfoot pain in an adolescent athlete. J Athl Train. 31: 71-73, 1996.
21. Khurana JS, Mayo-Smith W, Kattapuram SV. Subtalar arthralgia caused by juxtaarticular osteoid osteoma. Clin Orthop 252: 205-208, 1990.
22. Ghanem I. The management of osteoid osteoma: updates and controversies. Curr Opin Pediatr 18: 36-41, 2006.
23. Rosenthal, DI. Radiofrequency treatment. Orthop Clin North Am 37: 475-484, 2006.
24. Finstein JL, Hosalkar HS, Ogilvie CM, Lackman RD. An unusual complication of radiofrequency ablation treatment of osteoid osteoma. Clin Orthop 448: 248-251, 2006.
25. Mastrantuono D, Martorano D, Verna V, Manzini A, Faletti C. L´osteoma osteoide. Nostra esperienza nel trattamento mediante radiofrequenza (RF). Radiol Med 109: 220-228, 2005.
26. Ghanem I, Collet LM, Kharrat K, Samaha E, Deramon H, Mertl P, Dagher F. Percutaneous radiofrequency coagulation of osteoid osteoma in children and adolescents. J Pediatr Orthop 12B: 244-252, 2003.
27.Lindner NJ, Ozaki T, Roedl R, Gosheger G, Winkelmann W, Wortler K. Percutaneous radiofrequency ablation in osteoid osteoma. JBJS 83B: 391-396, 2001.


Address correspondence to: Luis Rafael Ramos-Pascua. Complejo Hospitalario Universitario de León. Altos de Nava s/n, 24071, León, Spain. Email: luisramospascua@gmail.com

1   Head of Orthopedic Surgery Department, at the University Hospital of León (Spain).
2  Assistant Doctor. Department of Radiology. University Hospital of Salamanca. Spain.
3  Assistant Doctor. Department of Orthopaedic Surgery. University Hospital of León. Spain.
4  Assistant Doctor. Department of Radiology. University Hospital of Salamanca. Spain.
5  Assistant Doctor. Department of Orthopedic Surgery. University Hospital of León. Spain.

© The Foot and Ankle Online Journal, 2011