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Addressing An Aneurysmal Bone Cyst Occupying The Majority of the Talus
In a provocative case study, the authors discuss the diagnosis of an aneurysmal bone cyst in a 21-year-old female and subsequent treatment with bone grafting and platelet-rich plasma.
An aneurysmal bone cyst is a benign tumor commonly affecting the metaphysis of long bones but it can occur in any bone. These bone cysts typically cause localized pain and swelling that leads to limitation of physical activity. In time, this neoplasm can lead to pathologic fractures and biomechanical strain. A high index of suspicion for aneurysmal bone cyst is warranted when patients present with chronic ankle pain.Surgical intervention is necessary before this benign tumor expands to articular surfaces, which will limit the rearfoot complex.1,2
Aneurysmal bone cyst of the lower extremity, particularly the talus, is not widely reported in the literature due to its rare occurrence. With this in mind, we present a case of a young female who was diagnosed with an aneurysmal bone cyst occupying the majority of the talus bone. We subsequently performed intralesional curettage and utilizing bone graft infused with platelet-rich plasma to achieve excellent results and complete resolution of symptoms.
A 21-year-old female was referred to our practice by another podiatric physician in November 2017 with chronic foot and ankle pain for four years. She stated the pain had significantly worsened over the last six months, and pointed to the entire ankle and rearfoot as the source of her pain. The patient had discomfort with palpation, manipulation and range of motion within the rearfoot complex. Prior to presenting to our practice,the patient already had multiple sets of X-rays and multiple MRIs. Her X-rays revealed a large osseous void encompassing the majority of the talar head and neck, and half of the talar body. The MRI revealed a hemorrhagic cyst, which occupied the majority of the talus. The cyst alsoextended to the subchondral region anteriorly at the articulation with the navicular and with the sustentaculum tali at the medial subtalar joint (see Figure 1).
She had been utilizing a CAM walker boot for stability and symptom relief. The patient related anxiety associated with her condition along with limitation of quality of life and activity leveldue to pain. We discussed conservative and surgical treatments with the patient, who chose to proceed with surgical intervention. The proposed surgical plan was for excision and curettage of the bony cyst, and subsequent packing of the area with platelet-rich plasma (PRP)-infused bone graft.
Pertinent Steps To Achieving ‘Complete Resolution Of The Aneurysmal Bone Cyst’
After ensuring general anesthesia and supine positioning for the patient, we performed an ankle arthrotomy to expose the dorsal talar head and neck. The bone had a dark, abnormal color and was fragile. We created a window was in the talusdorsally at the talar neck and found the bone was filled with mostly sanguinous fluid (see Figure 2). The entire head, neck and most of the body of the talus was void of bony trabeculae. We suctioned the bloody fluid, curetted the bony cavity thoroughly and sent the sample to pathology for evaluation.
The pathology report revealed that the lesion consisted of lamellar bone as well as multiple cystic membranes with areas of fibrosis and giant cells, findings that were consistent with an aneurysmal bone cyst (see Figure 3). After completing the curettage, we obtained platelet-rich plasma from the patient, prepared and mixed it with corticocancellousbone graft. We subsequently packed the talar void with the bone graft/PRP mixture. After completing the procedure, we had the patient utilize a posterior splint non-weightbearing.
Computed tomography (CT) nine weeks after the procedure showed maintenance of the talar dome contour along with bone graft incorporation (see Figure 4). At this point, we allowed weightbearing in a protected boot. At seven months postoperatively, we gave the patient clearance to resume full activities and exercise. Radiographs revealed excellent incorporation of the talar bone graft with complete resolution of the aneurysmal bone cyst (see Figure 5). At 14 months, the patient denies any limitations or pain.
Current Insights On The Etiology, Diagnosis and Treatment Of Aneurysmal Bone Cysts
Clinicians have described aneurysmal bone cysts as benign, osteolytic, locally expansive and aggressive lesions. However, their nature and histogenesis are still unclear. Some authors believe an aneurysmal bone cyst is due to local vascular disturbances that consist of blood-filled channels that leads to increased pressure.1,2 Others propose that they could result from a traumatic injury trigger but the mechanism is unknown.3 Oliveira and colleagues have proposed a chromosomal component for the basis of aneurysmal bone cyst development as well.4
Aneurysmal bone cyst favors the metaphysis of long bones and can occur in patients of all ages. However, 75 to 90 percent of cases occur before patients reach their third decade of life.5 The majority of the tumors that appear in the foot are in the metatarsals and calcaneus. Lesions such as aneurysmal bone cysts of the talus are extremely rare.6,7
Pain is the most common reason patients seek medical treatment for these lesions. Many will have ankle swelling and pain arising from an increase in intraosseous pressure.8 Podiatrists should suspect an aneurysmal bone cyst if they see an expansive, lytic metaphyseal lesion with an “eggshell” sclerotic rim and a “soap bubble” appearance on plain radiographs.2 While the cortex is usually intact, it may be thin. The osteolytic core may exhibit a honeycomb pattern.9 A bone biopsy, which usually reveals osteolucent bonewith multiloculated giant cells and inflammatory cells among red blood cells, is essential for diagnosing an aneurysmal bone cyst.
Regardless of the etiology, treatment of an aneurysmal bone cysts consists of debridement of the lytic area with subsequent use of an adjunctive bone graft. Bone grafting is recommended to provide mechanical support as well as to eliminate the dead space and reduce aneurysmal bone cyst recurrence.10,11
What Other Case Reports Have Revealed About Treatment And Recurrence
Sharma and colleagues reported on an aneurysmal bone cyst located at the talar head and neck, which they managed with intralesional curettageand bone graft.6 They allowed the patient to bear weight at 12 weeks and the authors report no evidence of recurrence at the two year follow-up.6 Shazly and colleagues discussed the use of arthroscopic curettage and bone grafting in two patients with aneurysmal bone cysts.12 These patients returned to activity at 11 weeks and no recurrence was evident at their one-year follow-up.12
Vosoughi and colleagues present a case, which involved recurrence of an aneurysmal bone cyst eight months after primary curettage and autologous bone grafting.13 The patient had a second curettage, bone grafting and tibiotalocalcaneal arthrodesis.13 The study authors noted an arthrodesis was necessary to maintain the integrity of the lower extremity.
In our aforementioned patient, we augmented a bone graft with platelet-rich plasma (PRP) in order help facilitate bone graft incorporation and healing. PRP is a source of critical bone healing factors, which transduce intracellular signals for chemotaxis, cell proliferation and osteoblast differentiation.14
In Conclusion
While our aforementioned patient’s intraosseous lesion occupied the majority of the talus bone and extended to the articular surfaces, the lesion existed more anteriorly within the talus, sparing the tibiotalar and subtalar joints. Our patient responded very well to bone grafting and PRP incorporation. She was able to resume activity without pain or limitations. The talonavicular joint does show early signs of degenerative arthritis but the patient remains asymptomatic and did not require a primary arthrodesis.
Aneurysmal bone cysts are rare pathologic findings in the talus bone. Surgeons can effectively treat these cysts with curettage and bone grafting with PRP, an approach which has excellent results as evidenced by our case study.
Dr. Miller is an Attending Physician at the St. Joseph Medical Center Podiatric Surgical Residency Program in Houston.
Dr. Gebresenbet is an Attending Physician at the St. Joseph Medical Center Podiatric Surgical Residency Program in Houston.
Dr. Singh is a second-year resident at the St. Joseph Medical Center Podiatric Surgical Residency Program in Houston.
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