European Journal of Cardiovascular Medicine

An aneurysmal bone cyst (ABC) is a benign, locally expansive lytic bone lesion characterized by blood-filled spaces divided by septae, which contain osteoid tissue and multinucleated osteoclast cells. This lesion most frequently occurs in the metaphysis of long bones and is commonly seen in individuals during their second decade of life [1-3]. It can also arise as a secondary phenomenon following other primary bone tumors, such as telangiectatic osteosarcomas, fibrous dysplasia, giant cell tumors, hemangiomas, osteoblastomas, chondroblastoma’s, and non-ossifying fibromas [4]. In such cases, secondary ABC represents a blowout expansion within a pre-existing lesion. Patients typically present with pain, swelling, and occasionally a pathological fracture [5]. Radiographically, ABCs appear as expansive, lytic lesions in the metaphysis, often associated with cortical thinning and subperiosteal new bone formation. MRI findings typically show multiple fluid-fluid levels and soft tissue expansion, with the presence of a solid soft tissue component suggesting a secondary ABC [6]. A biopsy remains the gold standard for diagnosis. Standard treatment involves curettage followed by bone grafting, though this method is associated with a significant risk of recurrence and morbidity [7]. The recurrence rate may be reduced, albeit with increased morbidity, through the use of adjunct techniques such as high-speed burrs and cryotherapy. Minimally invasive approaches, including sclerotherapy, radiotherapy, and embolization, are gaining popularity due to their lower associated morbidity.

This study aimed to compare the radiological and clinical outcomes of ABCs treated with polidocanol sclerotherapy, based on clinical and radiological diagnoses. Radiological outcomes will be assessed at regular intervals, evaluating bone healing using the Modified Neer’s criteria for radiological healing of bone cysts [8,9].

56 cases of ABCs were diagnosed. All of these cases were selected for polidocanol sclerotherapy (ST), with the diagnosis of primary ABC made based on clinical and radiological findings. Patients were included regardless of the size or location of the lesion. A minimum follow-up period of 24 months was ensured for all participants. Preoperative evaluations were performed using plain radiography, MRI, and CT scans. Cases of secondary ABC were excluded from the study.

Sclerotherapy Technique: The procedure was performed under local anesthesia (2% Xylocaine) with aseptic precautions and was guided by CT imaging. A core biopsy needle was used to obtain samples of lining cells in all cases [10]. In classic ABCs, blood was typically aspirated. Approximately 10 ml of aspirated blood, along with any lining tissue obtained from the biopsy, was sent for pathological examination. An 18G needle was used to break the septae by moving in various directions. After injecting the sclerosant, the area was sealed for 10 minutes to prevent extravasation, which is critical to avoiding soft tissue necrosis. The volume of sclerosant (1 ml of 3% polidocanol per 1 cm³ of the lesion) was determined via CT scan, with a maximum of 12 ml (360 mg) injected per lesion. The sclerosant used was 3% polidocanol (hydroxypolyethoxydodecan) available in 2 ml ampoules, with 1 ml containing 30 mg of polidocanol.

Follow-Up: Patients were followed up 10 days after the initial injection, and subsequently at 3, 6, 12, and 24 months. During follow-up visits, outpatient radiological assessments of the lesion (cortical sclerosis, volume reduction, and cavity opacification) were conducted along with clinical evaluations of the patients' symptoms Features suggestive of healing included resolution of pain and cortical thickening on radiological examination, without any increase in cyst size. A second dose of sclerosant was administered if there were no signs of healing. Radiological healing was assessed using Modified Neer’s criteria [11].

Statistical Analysis: Data were analyzed using IBM SPSS (Statistical Package for Social Sciences) Version 23.

The study identified a total of 56 cases of aneurysmal bone cysts (ABCs) distributed across various skeletal sites. The majority of cases were observed in the distal femur, accounting for 21.43% of all cases. Proximal tibia and proximal humerus followed, representing 14.29% and 8.93% of the cases, respectively. The distal tibia also constituted 8.93% of cases. Other locations with notable occurrences included the proximal femur (7.14%) and clavicle (3.57%). The distribution was relatively sparse for sites such as the femur shaft, fibula, and metatarsal, each comprising only 1.79% of the cases. This distribution highlights the variability in ABC locations, with a concentration in the long bones of the lower extremities (Table 1).

Table 1: Site wise distribution of ABCs

Among the 56 patients who underwent sclerotherapy for ABCs, the mean age was 18.87 years, with a gender distribution of 33 males and 23 females. On average, each patient received 1.07 treatments over a mean duration of 4.3 months. Notably, there were no reported recurrences, indicating a favorable outcome for the sclerotherapy treatment regimen used in this study (table 2).

Table 2: Details of Sclerotherapy among study population

The preoperative Enneking staging (Table 3) revealed that a majority of the study population had active disease, constituting 55.36% of cases. Latent cases accounted for 16.07%, while aggressive cases were observed in 28.57% of the patients. This staging underscores a predominance of active and aggressive forms of ABCs within the cohort, which may influence treatment approaches and outcomes.

Table 3: Preoperative Enneking Staging of study population

The postoperative Neer scores (Table 4) at different time intervals (3, 6, 12, and 24 months) show a progression in patient outcomes. At 3 months, 22 patients were rated as 3, indicating a good outcome, while 2 patients were rated as 1. By 6 months, the majority of patients had a score of 2 (42 patients), reflecting continued improvement. At 12 months, there was a significant shift towards better outcomes, with 34 patients scoring 1. However, by 24 months, the majority of patients scored 1 (34 patients), with a slight decrease in scores of 2 (22 patients). Statistical analysis using Fisher's Exact test revealed no significant changes in scores across different time points, with p-values ranging from 0.25 to 0.92. This suggests stability in the treatment outcomes over time without significant variability.

Table 4: Post-Op Neer Score among study participants

Various treatment options are available for ABCs, ranging from extended curettage to minimally invasive sclerotherapy. Sclerotherapy has become widely practiced due to its advantages. Each treatment modality has its benefits and drawbacks. Currently, intralesional curettage, with or without bone grafting, is the accepted standard; however, lesions near the epiphyseal plate are associated with a higher recurrence rate and potential growth disturbances. To mitigate recurrence, techniques such as high-speed burring and cryotherapy are employed [12]. Common complications include bleeding, damage to the growth plate, and incomplete tumor removal [13]. Other treatment options include intralesional cryotherapy, sclerotherapy, radiation therapy, selective embolization, and extralesional en bloc excision with or without reconstruction.

Sclerotherapy, particularly with polidocanol, has shown promising results by leveraging Virchow's triad. Various sclerosants are available, including hypertonic saline, hypertonic dextrose, glycerin-based sclerosants, and alcohol [14]. Absolute alcohol is reported to be very effective for technically challenging and high-risk cases [15,16]. Recently, polidocanol has been used successfully as a sclerosant for conditions such as varicose veins, telangiectasis, and venous malformations [17]. It typically results in immediate thrombosis and complete ossification of lesions within two years. In our study, secondary ABC cases, such as those associated with giant cell tumors (GCT), were excluded. MRI findings of multiple fluid-filled cystic lesions separated by thin septa, indicative of blood collections, were used to differentiate benign lesions; a fluid level greater than two-thirds of the lesion volume generally suggests benignity [18]. The presence of solid areas within the lesion raises suspicion of secondary ABC, which was confirmed through biopsy.

In our study, 31 patients were treated with polidocanol, with a follow-up period of two years, showing a 100% healing rate even in aggressive cases. Most patients experienced symptomatic relief within six weeks and demonstrated cortical thickening on radiography by four months. These outcomes are comparable to those reported by Batisse et al. [18]. The mean residual lesion size was less than 25% of the initial lesion, with an average of 1.10 injections required; this is lower than the 3 injections reported by Rastogi et al. and Brosjo et al. [19,20].

No recurrences or malignant transformations were observed in patients treated with sclerotherapy. The procedure proved to be cost-effective, reducing the need for biopsy attempts, minimizing fluoroscopy usage, providing better cosmetic outcomes, and allowing for a day-care procedure. However, complications associated with sclerotherapy include hyperpigmentation, injection site necrosis, and hypopigmentation, which generally subside spontaneously. Local complications can be managed by preventing sclerosant extravasation.

Polidocanol sclerotherapy is a safe and effective treatment modality for aneurysmal bone cysts (ABCs). This approach offers several advantages, including its cost-effectiveness, favorable cosmetic outcomes, and reduced overall morbidity. The procedure can be conducted as a day-care intervention, which enhances patient convenience and reduces the need for extended hospital stays. Although local complications related to extravasation of the sclerosant can occur, these are generally self-limiting and resolve spontaneously. The prevention of extravasation, through meticulous technique and monitoring, is crucial in minimizing these complications. Overall, polidocanol sclerotherapy represents a promising option for managing ABCs, combining efficacy with a reduced risk profile and improved patient outcomes.

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