Medial malleolar osteotomy for intralesional curettage and bone grafting of primary aneurysmal bone cyst of the talus

Abstract

Access to the cystic lesion of the talar body without damage to the articular surface is difficult. This case report is about a 23-year-old man who had a symptomatic huge cystic lesion in the left-sided talus bone. Radiograph and CT scan showed an expansile lytic lesion within the talar body. The MRI revealed a well-defined lesion with fluid-fluid levels. The needle biopsy aspirate was haemorrhagic, and hence a diagnosis of the aneurysmal bone cyst was made. As the lesion was beneath the talar dome with an intact neck and head, a medial approach with medial malleolar osteotomy was performed. The lesion was curetted out, and the cavity was filled up with a morselised bone graft. The limb was splinted for 6 weeks, and complete weight bearing was started after 3 months. At 1-year follow-up, the lesion was found to be healed up, and the patient was pain-free with no recurrence.

Background

Cystic lesions in the talus are rare.^1–6 However, symptomatic large talar cysts can weaken the bone, and if remain untreated, they can lead to the collapse of the dome.⁷ The most common cystic lesions are intraosseous ganglion, simple bone cyst, aneurysmal bone cyst (ABC) and giant cell tumour of bone. The standard treatment of such lesion is curettage and bone grafting to provide mechanical stability until graft consolidation.⁸ However, access to the lesion in the talus is difficult.⁹ The available case reports or small series have adopted an anterior or posterior approach.2 6 7 10 As most of the surfaces of the talus are covered by articular cartilage, it is challenging to access the lesion without articular damage. In order to avoid articular cartilage damage, few surgeons have debrided the lesion with arthroscopy.^{9 11 12} However, arthroscopy has several limitations; it is a very useful tool for intralesional debridement but filling up the defect with bone graft through a small hole is inadequate. To the best of our knowledge, there is no report on medial malleolar osteotomy for intralesional curettage and bone grafting in the ABC of the talus. We present a case of ABC of talar body in a 23-year-old man who was treated with curettage and bone grafting through the medial malleolar osteotomy.

Case presentation

A 23-year-old male patient presented to the orthopaedic department with complaints of left ankle pain for 1 year. The pain was insidious in onset, dull-aching in character, and there was no radiation. The pain was aggravated on weight bearing, and it was relieved with analgesics and rest. He had no history of fall. There was no history of fever, chills, weight loss, loss of appetite, systemic illness or any previous surgery. The personal history and family history were not contributory. On physical examination, there was a visible diffuse swelling on the dorsal aspect of the foot, with no local rise in temperature but tender to deep pressure. The ankle range of motion was painful and restricted (dorsiflexion 0° and plantar flexion 15°), and there was no distal neurovascular deficit.

Investigations

The blood investigations (complete blood count, erythrocyte sedimentation rate, C-reactive protein, alkaline phosphatase, serum calcium) were within normal limits. The X-ray of the ankle showed a well-defined expansile lytic lesion with a thin surrounding cortical bone in the body of the talus. Fine thin septations were visible in the lesion with no matrix calcification or soft tissue swelling (figure 1). The CT scan revealed a lytic expansile lesion with multiple cortical breaches in the posterior and inferior talar aspect with no collapse of talar height (figure 2). The MRI showed a well-defined lesion within the talar body with fluid-fluid levels; it was hyperintense on T2 weighetd (T2W) and isointense on T1 weighted (T1W) images. The cortical breach was seen in the posterior aspect of the talus (figure 3). Needle biopsy revealed a haemorrhagic aspirate.

Figure 1.

Anteroposterior and lateral radiograph of left ankle shows an eccentric osteolytic lesion in the talar body.

Figure 2.

CT scan delineates the lesion inside the talar body.

Figure 3.

MRI shows hyperintense T2W signal inside talar body, but there is no involvement of surrounding soft tissue.

Differential diagnosis

Based on the clinical and radiological findings, a diagnosis of the ABC was made with differential diagnoses of giant cell tumour of bone and simple bone cyst.

Treatment

Treatment was planned in the direction of ABC. The talus was exposed by a medial approach through a medial malleolus osteotomy. An oval window of 2×3 cms was made on the medial wall of the talus, and a serosanguinous blood-filled slimy tissue was obtained from the talus body by curettage (figure 4). All the walls of the talar body were curetted till grating sensation was obtained. Subsequently, thermal (cautery) and chemical cauterisations (with hydrogen peroxide) were performed. The cavity was filled up with a morselised bone graft obtained from the preserved femoral head allograft; it was mixed with autologous bone marrow aspirate to increase its osteogenic potential (figure 4). Medial malleolus osteotomy was fixed with two partially threaded cannulated cancellous screws (4 mm, figure 5). The biopsy of the lesion confirmed the diagnosis as ABC. The ankle was immobilised with a below-knee plaster cast for 6 weeks. Then, he was allowed for partial weight bearing. Full weight bearing was started once radiological evidence of complete healing was evident (3 months).

Figure 4.

(A) Medial malleolar osteotomy was performed, and the medial cortical window was created in the non-articular part of the talar body. (B, C) The morselised bone graft harvested from the femoral head allograft was mixed with autologous bone marrow aspirate.

Figure 5.

The defect was packed with the morselised bone graft, and the osteotomised medial malleolus was fixed to the tibia with 4 mm cannulated screws.

Outcome and follow-up

He was followed up at 6 and 12 months. At the latest follow-up, he was completely pain-free, and there was no radiological evidence of recurrence (figure 6). The ankle dorsiflexion was 10°, and the plantar flexion was 30°.

Figure 6.

Postoperative radiograph at the end of 1 year shows consolidation of the graft without recurrence and talar dome collapse.

Discussion

ABC is a locally aggressive benign bone tumour that can arise primarily or secondarily along with giant cell tumour, fibrous dysplasia, non-ossifying fibroma, osteoblastoma, chondroblastoma, osteosarcoma and chondrosarcoma.^{3 4} The metaphyseal areas of the long bones are the common site for ABC, and it is rarely seen in the talus. The most common cystic lesion of the talus is an intraosseous ganglion cyst. Literature to date has a few case reports on talar ABC.2 6 7 9–12

Management of talar ABC is challenging because of the difficulty in access (sandwiched between tibia and calcaneum) and risk of pathological fracture secondary to the destruction of the bone by the tumour and because of its articulation to a major weight-bearing joint.^{9 11 12} The diagnosis of cystic lesion in the talus is equally challenging. The clinical and radiological findings may indicate the benign or malignant nature of the lesion only. The needle biopsy may be inconclusive as it can aspirate the blood or fluid within the lesion and often fail to obtain the tissue. The ultimate decision for surgery is based on the combined findings and most probable diagnosis.1 3 4 8 The presence of multiple blood-filled cavities lined by multinucleated giant cell osteoclasts and fibroblasts differentiate ABC from unicameral bone cyst.^{1 3}

The classical radiographical appearance of ABC is an eccentric radiolucent cystic lesion in the metaphyseal region that is surrounded by a thin layer of cortical bone. The trabeculations and cysts inside the lesion impart a multilobulated appearance, but it is not pathognomonic for ABC.³ It can also be visualised in the simple bone cyst, osteoblastoma and giant cell tumour. MRI is also used with X-rays to identify the extent and nature of the lesion completely. The specificity and sensitivity of diagnosing ABC are increased by the combined use of X-ray and MRI compared with their use in isolation. MRI can delineate fluid-filled levels, multiple internal septations, perilesional extension and surrounding oedema.³ CT is helpful in determining the osseous border and diagnosing any pathological fracture. Other than the nature of the lesion, the radiological findings help in the treatment decision. We decided to go for curettage and bone grafting as the talar dome was intact, and there was no collapse. Many authors reported excellent outcomes with intralesional curettage and bone grafting for lytic lesions that were well localised within the talus.2 6 9–12 However, partial or total talectomy and tibiotalocalcaneal arthrodesis have also been described for lesions that show extensive destruction of the talus and soft tissue or subtalar extension.⁷

The treatment goals for ABC are pain relief, preventing the progression to pathological fracture and recurrences.¹³ However, a safe and reproducible surgical approach must be adopted to reduce surgical site morbidity. The approach should allow adequate access for curettage and packing with bone graft. Previous reports describe the anterior or posterior approach to the talus, arthroscopic debridement and access through the articular cartilage.2 6 7 9–12 A report has mentioned the medial approach to the talus where the deltoid ligament was detached.⁷ Uysal et al recommended curettage and bone grafting through the osteochondral lesion; however, this can cause iatrogenic cartilage injury.¹⁴ Zhu et al described the anterior arthroscopic access to talar lesion for debridement and reported it as a safe approach as it precludes damage to the articular cartilage.⁹ However, the adequacy of filling up the defect with bone graft is difficult to assess through the arthroscope, and it can be technically challenging. The medial malleolar osteotomy provides adequate access to the talar body lesions and fractures.¹⁵ It is used mainly for the talar dome osteochondral lesion and fixation of complex talar body fractures. Kadam and Dhamangaonkar accessed the giant cell tumour of the talar body through the medial malleolus osteotomy.¹⁶ This approach has minimal morbidity as the bony healing is more consistent. It permits the medial window on the talar body that is non-articular. It provides excellent exposure to the talar body lesion, including direct visualisation of the articular part.

The small defect of the talar body can be left as such, whereas the large defect needs to be filled up with either bone cement or bone graft. The need for the voluminous graft to fill up the defect may incur numerous donor site morbidities. It can be minimised with the use of allograft; however, the osteogenic potential of the allograft is almost negligible. In order to augment the osteogenic potential of the allograft, it can be mixed up with autologous bone marrow or autologous bone graft. The adjuvant electrocauterisation and chemical treatment help in minimising the risk of recurrence.^{8 13}

This case report is unique as it describes a rare pathology in the talus, and the surgical approach for the talar lesion through the medial malleolus osteotomy is also uncommonly described. To conclude, curettage and bone grafting of ABC of the talar body can be safely performed through the medial malleolar osteotomy without violating the neck and head or the articular surface. The use of allograft reduces donor site morbidity and can be used for filling up a massive defect.

Patient’s perspective.

I got scared when I saw a swelling in my left ankle. It was not painful initially, and hence I neglected it for almost 1 year. I found the swelling growing in size, and it became painful enough to make me unable to bear weight. I visited my local doctor, and he advised me for an X-ray. He suspected it to be a tumour and referred me to the higher centre. That was the worst day of my life when I heard a tumour growing inside my body. I had never visited any doctor for any medical treatment before, and my first experience was something beyond my imagination. My parents and wife consoled me, and the next day I visited the hospital.

I was aware that doctors often refer to this apex hospital when something is challenging to treat, so I was pretty nervous. Even though I had to wait for 4 hours in the OPD, I waited for my turn patiently. The doctor asked me about the swelling in detail and advised for further investigations. Before leaving his station, I voluntarily asked the doctor about the tumour; he consoled me and told me that my condition is probably something called a ‘benign tumour’ that can be cured with surgery. I thanked the doctor and immediately rushed to the x-ray department for MRI and CT.

After examining the MRI, CT and x-ray, the doctor advised a needle biopsy examination. When I heard that a needle would be punctured into my bone, I requested him for complete sedation and full-body paralysed anaesthesia. He could understand my concern and told me that it would be painless. He injected some local anaesthesia into the skin of my ankle joint and inserted a needle under some X-ray like machine where he could see everything about my bone tumour site. He could aspirate only blood.

Then he told me that my condition is most probably a cyst inside the bone, which has a definite cure with surgery. He consented me for the procedure and told me that I would be operated on by a team of doctors. I could understand that the doctors were concerned about the access to the tumour as it was close to the ankle joint and covered by bones everywhere. They explained to me that they are going to break the inner side of my hindfoot bone to get access to the tumour. They will make a hole in the bone and will curette out the material inside it. They will fill up the defect with a bone graft from some other person that has already been preserved in their bone bank. They mentioned to me in details about preserved bone and their utility for such huge defect cases. I was happy that they had maintained the protocol of bone banking.

I was operated on under spinal anaesthesia, where the anaesthesia doctor injected some drug into my backbone. The orthopaedic doctors performed the surgery as explained. After removing the materials from the bone, they took the preserved bone from their bone bank and crushed it into small chips. The bone chips were packed into the cavity. I was in plaster for 2 months and off-weight. The doctors advised me for serial x-rays and started complete weight-bearing after 3 months. I recovered pretty well. I am back to my normal life. Thanks to the team of doctors who took care so nicely and showed their professionalism in treating me efficiently. I could understand that the surgical procedure was unique and it was a bit challenging, but after all, I was in safe hands.

Learning points.

• Curettage and bone grafting is the standard treatment for the symptomatic aneurysmal bone cyst. Although rarely seen, management of such benign tumours in the talus is challenging.

• Surgical access to the talar lesion incurs morbidity to the patient as most of its surfaces are covered with articular cartilage.

• The talar body lesion can be best accessed through the medial malleolar osteotomy and medial cortical window for curettage and bone grafting.

• Allograft mixed with autologous bone marrow aspirate is a good filler for the massive defect in the bone.