Keywords
Alcohol - ethanol - neoplasm - tumor - unicameral bone cyst
Introduction
Unicameral bone cyst (UBC), also known as simple or solitary bone cyst, is a primary
benign bone lesion. Radiographically, it appears as a centric single cavity in the
metaphysis of long bones such as in the proximal humerus and femur. Furthermore, it
could be developed in flat bones (e.g., calcaneus). UBCs are almost exclusively seen
in the first and second decades of life with male predominance. Often, UBCs are asymptomatic
and may resolve spontaneously with skeletal maturity.[1],[2],[3] Radiographically, the UBC could be classified as active or latent based on its distance
to the growth plate. When UBC is placed within 0.5 cm from the physis, it is termed
as active, and if the distance is more than 0.5 cm, it is labeled as latent.[4],[5] Although the exact etiology of UBC is unknown, several theories such as trauma,
elevated levels of prostaglandins, and venous congestion have been proposed.[6],[7],[8]
These ambiguities regarding the pathogenesis of UBC cause different methods of treatment
and many controversies about the choice of the best treatment.[6],[9] Management options include observation, injection, decompression, and surgical techniques
such as curettage and bone grafting in combination with different adjuvants. The aim
of this study was to evaluate the usefulness of ethanol as an adjuvant in a combined
four-step procedure including curettage, high-speed burring, ethanol 96%, and electrocauterization
followed by grafting to reduce local recurrence of UBCs.
Materials and Methods
Study design
In this retrospective cross-sectional study, medical records of all the patients with
UBC lesion treated from 2003 to 2013 were reviewed, retrospectively. Eligibility criteria
were patients with histological diagnosis of UBC lesion and full documented medical,
surgical, and follow-up records. The protocol of this study was conformed to the tenets
of the Helsinki Declaration of 1975, as revised in 1983, and was approved by the Local
Ethics Committee at our university.
Based on the patients' medical records, demographic data (age at the time of the surgery
and gender), the primary symptom of the patient, exact location of UBC lesion, pathologic
reports, and further surgeries were reviewed. Furthermore, the most recent available
images were studied to determine any possible recurrences.
Surgical technique
Suspicious lesions were treated with biopsy and curettage to determine the exact pathology.
Definite treatment of UBC lesions was conducted using our approach, called the combined
four-step alcohol-using approach, consisted of extended curettage, high-speed burring,
ethanol 96%, and electrocauterization of the lesion, consecutively.[10] Extended curettage was performed to remove all abnormal tissues. After using high-speed
burr on the walls of the lesion, the defect was irrigated by normal saline. In the
third step, ethanol 96% was carefully poured in the lesion with a syringe to fill
it completely. Any possible spill of ethanol in the surrounding tissues was suctioned
immediately. After 1 min, ethanol was evacuated by suction tube followed by irrigation
with normal saline. This cycle was repeated three times. Following irrigation to eliminate
the risk of explosion, electrocauterization of the lesion with monopolar coagulation
diathermy set to 50 W was performed on the whole wall of the lesion. The protocol
of combined four-step alcohol-using approach was carried out in lesions of any bone
of the body irrespective of the size or location except in the spinal region. Finally,
the void would be filled by autograft or allograft. We routinely used autograft from
the iliac crest to fill the defect, but allograft should be used for larger defects
in the children. Treating of pathological fractures was a little different; after
extended curettage, the fracture was reduced and fixed. After covering the periphery
of the fracture by multiple gauzes and using a suction tube to reduce the risk of
ethanol leakage, ethanol was spilled in the lesion. After electrocauterization, a
bone graft was impacted in the defect.
Statistical analysis
Data were entered into the Statistical Package for the Social Sciences software version
15.0 (SPSS Inc., Chicago, IL, USA). Demographic data and characteristics of lesions
were presented using descriptive statistics.
Results
During the study period, 21 patients with histological diagnosis of UBC were involved.
The follow-up period was 1–10 years. The mean age of the patients at the time of surgery
was 14 (range: 2–30 years). As demonstrated in [Table 1], nearly half of the cases were between 10 and 20 years of age, and most of them
were male (62%). About 62% of lesions were inactive and mostly seen on the left-sided
limbs of the body (57%). Humerus was the most common location of UBC lesions (62%),
followed by femur (28%). The most common presentation of lesions was a pathologic
fracture (43%).
Table 1
Demographic data of patients and characteristics of unicameral bone cyst lesions
|
Variables
|
n (%)
|
|
Age (years)
|
|
≤10
|
6 (28)
|
|
10-20
|
10 (48)
|
|
≥20
|
5 (24)
|
|
Gender
|
|
Male
|
13(62)
|
|
Female
|
8 (38)
|
|
Anatomic site of lesions
|
|
Femur
|
6 (28)
|
|
Humerus
|
13(62)
|
|
Fibula
|
1 (5)
|
|
Calcaneus
|
1 (5)
|
|
Side of lesions
|
|
Left limbs
|
12 (57)
|
|
Right limbs
|
9 (43)
|
|
First presentation of lesions
|
|
Pathologic fracture
|
10 (43)
|
|
Pain
|
6 (31)
|
|
Incidental
|
4 (21)
|
|
Mass
|
1 (5)
|
Totally recurrence has been observed in one patient among cases treated using combined
four-step alcohol-using approach [Table 2]. This case was a 5-year-old boy with UBC of the left calcaneus treated using extended
curettage with allograft insertion. He developed local recurrence of lesion 4 years
after surgery. The recurrent lesion was treated again as the same as the first procedure.
There is no evidence of recurrence in 5 years following the second operation.
Table 2
Treatment methods and recurrence rate
|
Treatments
|
Subject, n (%)
|
Recurrence, n (%)
|
|
Biopsy and curettage
|
3 (14)
|
0
|
|
Extended curettage + autograft
|
13(62)
|
1 (7.7)
|
|
Extended curettage + allograft
|
5 (24)
|
0
|
Discussion
The main goals in the treatment of UBC lesions are complete healing without any recurrence,
resolving pain, and decreasing the risk of pathologic fracture.[11] Although there is no any consensus on the best therapeutic modalities of UBC lesions,
invasive interventions and surgical treatments are preferred instead of medical therapies
such as diphosphonates and botulinum toxins.[6],[12] Intralesional injection of steroid or autologous bone marrow with or without demineralized
bone marrow may be a useful technique to treat UBC lesions.[1],[13],[14] Decompression and drainage of cyst fluid using cannulated screws are another choice
to treat UBCs.[15]
The classic management of UBC lesions is open curettage and bone grafting using autograft,
allograft, or bone substitute. Instrumentation after curettage and bone grafting could
be used to increase the stability.[9],[12],[16] Recurrence rate following open curettage and bone grafting or its substitute is
about 25%–37%.[15],[17] Hence, using an adjuvant can reduce the risk of recurrence.
Hou et al. used ethanol cauterization as an adjuvant in a minimally invasive curettage approach
in addition to synthetic calcium sulfate bone–graft substitute. They described shorter
time to solid union in UBC lesions treated by ethanol as an adjuvant in comparison
to the patients treated by open curettage and grafting. Moreover, no recurrence was
seen in cases for which ethanol was used.[17]
Nowadays, intracystic injection of alcohol is the best choice of UBC treatment with
low complication in some centers.[18] Moreover, the efficacy of ethanol to reduce recurrence rate after treatment of giant
cell tumor, aneurysmal bone cyst, osteoid osteoma, skeletal metastasis, and other
bone lesions has been described in the literature.[10],[19],[20],[21],[22] To the best of our knowledge, the efficacy of ethanol as an adjuvant therapy in
UBC lesions has not been described yet. In our study, we evaluated healing and recurrence
rate of UBC lesions after ethanol usage as an adjuvant with curettage and bone grafting.
We had only one recurrence among 18 cases (5.5%) received combined four-step alcohol-using
approach followed by grafting, either autograft or allograft.
The main limitation of our study was the number of patients. Hence, we could not assess
the effect of other variable factors such as the patients' demographic data and tumor
characteristics on healing or recurrence rate.
Discussion
The four-step alcohol-using approach may be a good choice of treatment with low recurrence
in patients with UBC lesions. However, certainly, studies with better design and more
sample size as well as extended follow-up are necessary.
Acknowledgment
This article has been obtained from a thesis submitted to the Shiraz University of
Medical Sciences in partial fulfillment of the requirement for the degree of specialty
in orthopedic surgery of Dr. Yaghoob Keikha. The project is sponsored by Bone and
Joint Diseases Research Center, Shiraz University of Medical Sciences.
