ISOLATED CAUTERIZATION AS AN ADJUVANT IN ThE TREATMENT Of BENIGN BONE TUMORS

Objectives: To evaluate the efficacy of cauterization as a sole adjuvant method in intralesional resection of benign bone tumors, taking into account associated factors that could influence local recurrence. Methods: 47 patients diagnosed with different benign bone tumors were included in this study, all of whom had been treated with curettage associated with cauterization as an adjuvant method. The medium follow-up was 32.7 ± 19.4 months. The recurrence rate was then evaluated in relation to age, sex, location of the tumor, histologic type, tumor grade (


INTRODUCTION
Benign bone tumors represent a heterogeneous group of bone lesions with variable histological characteristics and biological behavior.Although rarely lethal, they can result in important alterations of the bone architecture, causing not only mechanical fragility but also destruction of the adjacent joints. 1 These tumors are classified by the histological aspect or by their behavior and aggressiveness, where the staging system proposed by Enneking et al. 2 that divides tumors into latent (B1), active (B2) and aggressive (B3) is used the most often.The treatment of these lesions ranges from simple curettage to ample resection.Although simple curettage presents a greater risk of recurrence, ample resection increases morbidity and usually presents precarious functional results. 3Treatment should then be individualized, aiming to reduce recurrence and to preserve function.Initial studies showed that simple curettage presented high local recurrence, 4 especially in aggressive tumors.To reduce recurrence, various adjuvant methods were described, such as cryosurgery and intralesional application of phenol or ethanol. 3The use of these adjuvants reduces recurrence, but can increase complications such as pathological fractures and injury of adjacent soft tissues.Cauterization is a simple, low-cost method of easy access, but few studies describe its isolated use as a method adjuvant to intralesional resection of benign bone tumors.The aim of this study is to evaluate the results of isolated cauterization as a method adjuvant to the intralesional resection of benign bone tumors and the factors associated with the recurrence of these lesions, comparing its results with other methods described in literature.

PATIENTS AND METHOD
The study was approved by the ethics committee of the Orthopedics and Traumatology Service of Hospital das Clínicas da Universidade Federal de Minas Gerais (HC -UFMG) and of Santa Casa de Belo Horizonte.During the period from January 2002 to March 2008, 71 patients diagnosed with benign bone tumors were submitted to surgical treatment in the Orthopedic Oncology Service of HC -UFMG and of Santa Casa de Belo Horizonte.Forty-seven patients were included in the study, in which the treatment consisted of curettage and isolated cauterization with as an adjuvant method.Patients that were submitted to simple segmental resection (n=5), to reconstruction with conventional prostheses (n=2), reconstruction with non-conventional prostheses (n=8), reconstructions with arthrodesis (n=1) and patients with follow-up of less than six months (n=9) were excluded from the study.B1, B2 or B3), and size and type of material used to fill the tumor cavity (PMMA or autologus bone).The type and percentage of complications were also included in the analysis.Results: Global recurrence was 19.1%.There was statistic significance relating tumor grade to time to recurrence (p=0.028).No other factors were found that directly correlated with global recurrence of the tumors.Conclusion: Cauterization proved to be a simple, inexpensive and effective adjuvant method for the treatment of benign bone tumors.Level of Evidence: Level IV, case series.
The average age of the patients was 27.0±12.8years, with 32 (68.1%) males and 15 (31.9%) females.Follow-up time was 32.7±19.4(ranging from seven to 79 months).The patients were staged as proposed by Enneking et al. 2 and two (4.3%) patients were classified as B1, 27 (57.4%)as B2 and 18 (38.3%)as B3.All the cases, except for two patients (clinical diagnosis of non-ossifying fibroma) were confirmed by incisional biopsy using a trephine needle, and the histological types are listed in Table 1.The average size of the tumors was 8.4±3.8 cm (minimum of 1.5 cm and maximum of 18 cm).The femur was the most common location, affected in 14 (29.8%)patients.(Table 2)  Surgical treatment consisted of lesion opening through a wide bone window, which provided a view of the entire tumor cavity, allowing curettage with curettes in a series of sizes, until complete removal of the whole macroscopic tumor.The cavity was washed with margin expansion through abrasion boring.
Cauterization was performed all over the cavity, under direct visualization until the whole surface takes on a darkened appearance due to debris carbonized for 5 minutes.(Figure 1) After a further pulsatile washing with 0.9% saline solution, the cavity was filled by autograft, bioceramics or polymethylmethacrylate (PMMA).
The patients were monitored weekly until complete healing of the surgical site, then had monthly follow-up until the sixth postoperative month.From then on, they had clinical and radiographic follow-up every three months and follow-up through computed tomography or magnetic nuclear resonance of the surgical site.Simple chest x-rays were taken annually.In case of recurrence, the patients underwent further staging and a new local surgical procedure, including further curettage or resection with broad margins and reconstructions using prostheses or autografts.
Global recurrence was assessed and correlated with the following variables: age (above or below 20 years), gender, location (upper or lower limbs), histological type, staging (B1, B2, B3), size (larger or smaller than 10 cm), type of material used as filling (PMMA or bone graft).The rate and the type of postoperative complication were also analyzed.The data were evaluated through simple descriptive analysis and based on survival curves by the Kaplan-Meier method.
The univariate analysis was conducted through the survival curves with the log rank method and the multivariate analysis was conducted through the Cox model, considering p values <0.05 significant.The statistical study was carried out with the help of version 12.0 SPSS ® software (Chicago, USA).
In the univariate analysis, age (p=0.524),gender (p = 0. 217), location (p=0.581) and bone with tumor (p=0.928) did not present significant correlation with local recurrence.In the comparison among histological types no greater occurrence was observed in a specific type of tumor either (p=0.246).As regards lesion size, there was no significant correlation with recurrence (p=0.642).
Staging was not a variable that presented correlation with recurrence (p=0.245);however, the recurrence of B3 tumors occurred at an average 6.4±2.0 months; while the B2 tumors recurred at 23.5 ± 18.7 months, considered a statistically significant difference (p=0.028).(Figure 2) Regarding the type of surgery performed, relapses occurred in six (30%) patients submitted to filling with autograft and in three (18%) of the patients submitted to reconstruction with PMMA; however, this difference was not significant in the univariate analysis (p=0.345).
In evaluating complications, we observed four patients that presented postoperative complications with two (4.4%) cases of fracture and one (2.2%) of infection.
The multivariate analysis conducted through the Cox model did not show significance among the studied variables either.

DISCUSSION
The treatment of benign bone tumors is based on histological type, location, size and the biological behavior of these lesions.The main challenge in the treatment of these tumors is to balance low surgical morbidity with acceptable rates of local recurrence.Initial reports of simple curettage, especially of giant cell tumors, showed recurrence rates of up to 60%, suggesting more aggressive methods for local control of these lesions. 5Capanna et al. 6 obtained recurrence of 45% in 280 patients treated with curettage compared to 18% in 387 in which some adjuvant method was added.][5][6][7][8][9][10][11][12][13][14][15][16][17][18] (Table 3) The most frequently used include application of phenol, cryotherapy and cavity filling with PMMA.Phenol is used extensively as an adjuvant.After curettage, the phenol is sprayed inside the lesion or applied with the help of a swab, causing tissue necrosis at a depth of around 1 to 2mm. 19As it is extremely caustic, it must be handled with care, protecting the adjacent soft tissues.Moreover, it can be absorbed and result in undesirable effects in other organs such as the heart, lungs and liver.
Recurrence time GCT-giant cell tumor; ABC -aneurysmal bone cyst; PMMA -polymethylmetacrylate recurrence was 18%, while those filled with autograft had recurrence of 30%, suggesting that the use of cement can help in the local control of benign bone tumors, which is consistent with the findings of Camargo et al. 22 , who suggests adjuvant action of the bone cement.PMMA also presents the advantages of immediate mechanical stabilization and ease in recurrence identification. 2ur study also observed that tumors considered aggressive (B3) recur earlier than active tumors (B2), suggesting that less aggressive benign tumors should also be monitored for longer periods of time.We also observed a low incidence of complications that occurred in 6.7% of the cases.The risk of pathological fracture was also lower than other methods, especially in the treatment with cryotherapy that presents an incidence of complications above 10%. 11

CONCLUSION
Cauterization proved efficacious as an adjuvant in the treatment of bone tumors, with results similar to the other methods described in literature and with low incidence of complications.
Another method is cryotherapy, performed through the application of liquid nitrogen in the cavity with protection of the adjacent tissues using heated saline solution.The nitrogen acts by creating intracellular ice crystals, which will injure the cell membrane and cause necrosis of the exposed tissue, reaching a depth of about eight to 10mm. 20It has a higher cost and its main complication is fracture resulting from persistent bone lesion. 17n our study, we used cauterization on its own as an adjuvant method.Some studies report its use, but in association with other methods such as phenol application. 15][7][8][9][10][11][12][13][14][15][16][17] We also observed that the rate of complications is low, with little repercussion in the adjacent tissues and with a low cost of use.
A controversial point is the use of PMMA as an adjuvant.Some studies suggest that PMMA would increase the tumor resection margin due to thermal and cytotoxic effects; however, other studies showed similar rates of recurrence with or without filling with PMMA after GCT curettage 21 .In this study, we observed that, although not significant, in tumors completed with PMMA

Figure 1 .
Figure 1.Preoperative aspect after performance of curettage and cauterization.

Figure 2 .
Figure 2. Local recurrence time according to the staging of Enneking et al. 2 (months).
All the authors declare that there is no potential conflict of interest referring to this article.

Table 1 .
Histological types of benign tumors.

Table 2 .
Distribution of tumors by anatomical location.

Table 3 .
Local recurrence according to different adjuvant methods.