|Year : 2019 | Volume
| Issue : 4 | Page : 350-353
Osteoid osteoma of the calcaneus misdiagnosed as subtalar sprain
Sandeep Vijayan, Chirag Jain, Monappa Aroor Naik, Sharath Kumar Rao
Department of Orthopaedics, Kasturba Medical College, Manipal Academy of Higher Education, Manipal, Karnataka, India
|Date of Web Publication||11-Oct-2019|
Department of Orthopaedics, Kasturba Medical College, Manipal Academy of Higher Education, Manipal, Karnataka
Source of Support: None, Conflict of Interest: None
Osteoid osteoma of foot and ankle account for ten percent of benign bone tumors and commonly involve the talus and metatarsals. Its occurrence in calcaneus is extremely rare and can mimic ankle instability, subtalar arthritis, osteochondritis or plantar fasciitis leading to delay in diagnosis. We present the case of a 17 year old boy with periarticular osteoid osteoma in the calcaneum, who presented following an ankle sprain. He was successfully treated with CT guided percutaneous radiofrequency ablation and we feel that it is a safe, precise and effective treatment option for even periarticular osteoid osteoma in the foot and ankle region.
Keywords: Calcaneum, osteoid osteoma, periarticular, radiofrequency ablation, subtalar sprain
|How to cite this article:|
Vijayan S, Jain C, Naik MA, Rao SK. Osteoid osteoma of the calcaneus misdiagnosed as subtalar sprain. Indian J Cancer 2019;56:350-3
| » Introduction|| |
Osteoid osteoma is a primary benign osteoblastic tumor with affinity for appendicular skeleton. Its occurrence in the foot is rare and mainly involves the talus and metatarsals. It can mimic various other pathologies in the foot and can lead to diagnostic dilemma. Radiofrequency ablation of the tumor is currently accepted as a treatment option for osteoid osteoma in long bones. Due to the possibility of damage to the articular cartilage and adjacent neurovascular bundle, its use in subchondral lesions in flat bone is generally not preferred. We describe here a case of osteoid osteoma involving the subchondral region of the calcaneum that was successfully treated with radiofrequency ablation and further try to understand the etiopathogenesis and treatment options of this tumor.
| » Case Report|| |
A 17 year old boy presented with vague pain around the left ankle of 9 months duration after twisting his ankle. Initial plain radiographs of the ankle taken elsewhere were normal. He initially improved with analgesics, but later his pain got aggravated. Pain was more in the morning and after walking, and was relieved with non-steroidal anti-inflammatory drugs (NSAIDs). It was not associated with swelling, ankle instability, or constitutional symptoms. In view of the twisting injury, an ankle brace was given. However, he remained symptomatic and came to us with a magnetic resonance imaging (MRI). On examination, there was no swelling, deformity, or skin changes over the left ankle. Mild tenderness was noted on the posteromedial aspect of the ankle and adjacent retrocalcaneal area. Subtalar eversion was painful, but ankle movements were normal. Fresh radiographs showed a suspicious lucent area with adjoining calcification in the calcaneum posterior to the subtalar joint [Figure 1]. MRI showed a hyperintense lesion in the posterior calcaneum on T2-weighted images with surrounding marrow edema and normal signal intensity of ligaments. Computed tomography (CT) scan of the hind foot clearly demonstrated a small sclerotic focus suspicious of osteoid osteoma in the superior aspect of calcaneum along the talo-calcaneal joint, without cortical thickening or periosteal reaction [Figure 2]. He underwent percutaneous CT-guided radiofrequency ablation (RFA) of the periarticular lesion under general anesthesia. Under image guidance a 2.5-mm drill hole was made till the nidus, after which a radiofrequency probe (Celon AG with 1.5 cm ablation length) was introduced till the distal edge of the lesion and ablation with 1 KJ energy at a voltage of 5–9 KV was applied for 12 minutes [Figure 3] and [Figure 4]. He was permitted full weight bearing with an elbow crutch for 3 weeks. Within 3 days of the procedure he had complete relief of pain and continues to remain pain-free after 2 years without radiological evidence of subtalar arthritis or osteonecrosis [Figure 5].
|Figure 1: Lateral radiograph of the left ankle and foot showing a suspicious sclerotic island of bone with adjacent lucency in the posterior subtalar area of calcaneum (circled area)|
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|Figure 2: Sagittal computed tomography slices showing the sclerotic focus in the superior aspect of calcaneum along the subtalar joint line without adjacent cortical thickening or periosteal reaction (line)|
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|Figure 3: Intraoperative sagittal computed tomography images showing the radiofrequency probe at the nidus before ablation|
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|Figure 4: Intraoperative photograph with the radiofrequency probe in situ through a protective soft tissue sleeve|
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|Figure 5: Lateral radiograph of the left ankle and foot at 2 years of follow-up showing no evidence of tumor recurrence, subtalar arthritis, or osteonecrosis|
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| » Discussion|| |
Osteoid osteoma was first described by Bergstrand in 1930. Later, Jaffe in 1935 defined it as a primary benign osteoblastic tumor.,,, The tumor is characterized by a central nidus formed of osteoid tissue within a highly vascularized connective tissue matrix and constitutes about 10–12% of all benign bone tumors, is three times more common in males, affects children and young adults, and is usually located in the appendicular skeleton.,,,,, Over a period of time the nidus stimulates the production of dense bone around it. The reported incidence of osteoid osteoma in the foot and ankle is around 6–15% with predilection for talus and metatarsals;,, and in the calcaneum, the incidence is around 2–3%.,
The characteristic clinical feature is nocturnal pain relieved by NSAIDs. This is due to the presence of nerve fibers and production of prostaglandin E2 at the site of the tumor leading to local vasodilatation and its suppression by NSAIDs resulting in pain relief.,,,, Other features include local tenderness, soft tissue swelling, warmth, and disuse atrophy with muscle weakness. Periarticular location of the lesion may be associated with growth disturbances, joint contractures and synovitis., Diseases like retrocalcaneal bursitis, sinus tarsi syndrome, subtalar sprains and arthritis, tarsal tunnel syndrome, Achilles tendonitis, Sever's disease, and plantar fasciitis can present with unexplained or persistent hind foot pain and mimic osteoid osteoma of the calcaneum.,
Unlike in long bones, where on plain radiographs a mature lesion will show the characteristic radiolucent nidus with surrounding thick sclerosis, in the foot, the tumor is usually in the cancellous or intra-articular part and periosteal reaction is often absent.,,,,, For the same reason, in our patient also, the lesion in the calcaneum was missed on initial plain radiographs and misdiagnosed as subtalar sprain. Various investigative modalities are available for diagnosis [Table 1].,,,,
|Table 1: Investigative modalities for confirming the diagnosis of osteoid osteoma|
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Osteoid osteoma is a self-limiting lesion. Pain may disappear at an average of 5–6 years (probably by bone infarction)., Patients still opt for surgical treatment due to severe pain. Definitive treatment consists of open surgical resection or CT-guided percutaneous ablation of the nidus.,,,,,
Literature review shows that osteoid osteoma in the foot and ankle is mostly treated by en block resection and bone grafting due to greater risk of injury to the nearby neurovascular bundle and predisposition to osteonecrosis due to small size of the bones.,, However, open surgical resection is associated with intraoperative difficulty in localization of the lesion, fractures due to extensive resection, recurrence due to incomplete resection, damage to articular cartilage in periarticular lesions, prolonged protected weight bearing, longer convalescence period, and scarring.,,,, In view of the considerable morbidity associated with open resection, recently few authors have suggested CT-guided percutaneous ablative procedures [Table 2].,, Open resection will be needed when the lesion is within a centimeter of the neurovascular bundle, there is doubtful histology and symptomatic recurrence even after two percutaneous ablative procedures.,
Among all the percutaneous techniques, CT-guided RFA is most popular due to its safety and efficacy, minimal invasiveness, small probe diameters, and high success rate with least complications.,,,, Use of RFA for the treatment of osteoid osteoma was first published by Rosenthal.,,, High-frequency alternating current at 500,000 Hz is transmitted by radiofrequency probes. It causes local ionic agitation and frictional heat leading to coagulation necrosis of the lesion around a diameter of 1–1.5 cm., The development of cooled probes allows application of more energy and more zone of coagulative necrosis without excessive charring. Typically, osteoid osteoma lesions are smaller than 1 cm and can be completely ablated with radiofrequency., The main disadvantage of this procedure is the lack of histological confirmation of the lesion. However, using a core drill biopsy prior to RFA is helpful in confirming the tissue diagnosis. Minor complications like skin burns, skin fistula, vasomotor instability, and cellulitis have been reported following RFA.,
Usually, after the primary radioablative procedure there is no need of further radiological studies, unless there is doubt of recurrence or failure of treatment. Post-ablation, the zone of coagulated tissue is most accurately demonstrated using a contrast-enhanced MRI (T1 weighted)., Immediate excruciating pain due to tissue necrosis subsides within 24–48 hours. If pain persists beyond 1 month it is considered as failure of treatment and further therapy is warranted. A second RFA is usually successful. If symptoms recur, then surgical resection must be employed. Most recurrences occur in primary lesions which are larger than 1 cm in diameter and commonly occur during the first year after primary treatment.,
RFA for calcaneal osteoid osteoma is safe and is an effective treatment option that can be done as a daycare procedure and patients can resume their daily activities without casts or splints. There is no risk of developing arthritis or osteonecrosis even when used for periarticular lesions. A high index of suspicion for osteoid osteoma should be present to avoid misdiagnosis when young adults present with post-traumatic atypical symptoms which fail to respond to standard nonoperative treatments and warrants additional imaging studies like CT or MRI.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
The authors would like to express their sincere gratitude to Dr. Sathish Babu, Associate Professor of Radiodiagnosis and Prof. Rajgopal, Head of Department of Radiodiagnosis, Kasturba Medical College, Manipal for their expert opinion and help in doing the percutaneous ablation.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2]