The standard treatment of ABC is curettage with or without bone-graft. Despite the best efforts at curettage, postoperative highly variable recurrence rates have been shown. As a result, various auxiliary methods have been evolved to reduce the recurrence including the use of cement, high-speed burr, argon beam, phenol, and cryotherapy. Most of our patients had disabilities because of the tumor and their treatment, although none of them died or required amputation. It is difficult to treat ABC in the stage of aggressive period. Lesions that occur in the proximal femur should be treated more aggressively, partly because of the high rate of local recurrence and the high risk of fracture. The most appropriate techniques for some of these tumors are curettage surgery and allograft implantation. However, the living quality of the recurred patients significantly reduced.
Up to now, the cause of ABC is still unknown. Traditionally, the current consensus believed that it is associated with the pressure increase in local blood vessels. In 1950, Lichtenstein et al . proposed that the ABC should not been defined as a bone tumor, but a reactive disease of increased intraosseous pressure caused by intraosseous vasogenic disorder (intraosseous phlebemphraxis or arteriovenous fistula). In 1995, Kransdorf et al . described the ABC foci as a formation of hemorrhage, and they proposed that continuous bleeding from intraosseous blood capillary created a cavity. Osteolytic change could be a result of rapid expansion of the sclerotin in the lesion area bone cysts formed. According to Mirra et al .the so-called aneurysmal bone cyst is not a cyst nor a neoplasm; rather, it is probably a periosteal to arteriovenous malformation in bone, not uncommonly seen in association with other well-known benign and even malignant lesions. In the last 10 years, however, many researchers proposed that the formation of ABC was correlated with gene mutation, and believed that the ABC was a bone tumor, not a disease caused by local bleeding.
Ye Y et al . believed that primary ABC has now been identified as an independent neoplasm. The oncogenes responsible for ABC is formed secondary to gain-of-function translocations of t(16;17) (q22;p13) involving a gain-of-function of TRE17/USP6 (ubiquitin-specificprotease USP6 gene). In ABC, this mutation causes the induction of matrix metallopro- teinase (MMP) activity via NF-kB. They think that ABC has no malignant potential although the USP6 gene activatied. Oliveira et al.[12−13] believed that primary ABC was a tumor originated from mesenchymal cells, and they found that there was rearrangement of one or two oncogenes in USP6 (ubiquitin-specific protease 6) and CDH11 (cadherin 11 gene) in the patients with primary ABC, and that there was chromosome translocation in T (16;17) (q22;p1). They also found that the oncogene USP6 was in a very active state under the regulation of CDH11 promoter, but there was no translocation of CDH11 or USP6 in the patients with secondary ABC.
In this study, all of the patients had primary ABC, with good health status evaluated by each system, and without manifestations of malignant tumor. All of the patients of the 2 groups achieved satisfactory efficacies after receiving different treatment protocols, but the efficacy of the study group was superior to that of the control group.
Curettage and bone grafts with high-speed burring is the main treatment of ABC. At present, there were few literatures reported the theoretical basis for the application of ESIN in primary ABC. In 2015, Erol B et al. proposed to take the curettage and bone grafts with high-speed burring assisted by the fixation with steel plate, ESIN or Kirschner wire, etc. as the treatment method of primary ABC. They found that internal fixation in specific locations can promote healing rate in most of the ABC cases. Classified postoperative NEER grading of the children into 2 classes, namely the recurrence (grade I and II) and cured (grade III and IV).Our data showed that the recurrence rate of the patients in the study group(18.75%) was significantly lower than that of the control group(60%),This result indicated that the use of ESIN could reduce the recurrence rate (P < 0.05). However, the molecular mechanism of which should be further studied in patients with primary ABC. Meanwhile, we also found that the time of postoperative plaster immobilization of the patients in the study group was significantly shorter than that of the control group. Additionally, the patients in the study group did not have pathological bone fracture after recurrence and the result of MSTS functional evaluation of recurrenced cases indicated satisfactory efficacy. According to above data, we could find that the internal fixation with ESIN can not only increase the cure rate of the patients with primary ABC, reduce their recurrence rate, but also significantly reduce the time for postoperative plaster immobilization of the patients and the risk to have another pathological bone fracture, and also significantly improve postoperative life quality of the patients. Meanwhile, we also found that the recurrence factors may be correlated to the lesion location, but statistical analysis indicated no statistical significance. We believe that the use of ESIN in the treatment of primary ABC has following advantages: (1) With its good elasticity, each ESIN is able to form 3 supporting points in the medullary space; 2 nails are distributed in the medullary space to form double arches, which is a central -type internal splint fixation; the mechanical conduction after fixation is a stress sharing mode, which brings less interference to normal biomechanics of the limbs. The nails provide at least 4 kinds of stability of biomechanics, namely counter-bending stability of axial stability, lateral stability and counter-rotation stability, which can effectively prevent displacement, angulation and rotation after fixation, therefore, the nails can significantly reduce the time of postoperative plaster immobilization of the patients and improve postoperative life quality of the children. (2) Based on the pathogenesis of the ABC, Biesecker et al. supported the hypothesis that ABC was a secondary reactive lesion of bone occurring owing to hemodynamic disturbances based on the results of manometric pressure studies showing increased intracysticpressure. Marcove RCet al. suggested that arresting this hemodynamic disturbance could induce healing and prevent recurrence. Healing therefore may occur either spontaneously or after biopsy or fracture. Therefore, we hypothesis that fixation ESIN can achieve the effect of continuous intracapsular drainage, and thus reduce intracapsular pressure, promote healing and reduce recurrence. Furthermore, compared with Kirschner wire, ESIN is located in the marrow cavity, and it brings less foreign body reaction to surrounding tissues and could reside in body for a long term. (3) After long-term follow-up for the patients of both groups, it was found that all of the recurrenced cases in the study group had no pathological bone fracture, and we believe that when the recurrenced area is located in the stress bone (femur or tibia), the internal fixation with ESIN can provide protection and significantly reduce the risk of refracture.
In this study, most of the ABC located at the neck of the femur which is near the metaphysis and is a stress bone in both of the 2 groups. Some researches recommended to curettage and bone grafts with high-speed burring, assisted by internal fixation with steel plate, but local bone cortex of ABC was injured in an osteolytic manner, so it needs to be further discussed whether the internal fixation with steel plate can play a role on the prevention of pathological bone fracture and stabilization once there was a recurrence or expansion of the lesion (Fig. 5). Due to its poor stability, the kirschner wire can hardly play the role of secure internal fixation. Hutchinson PH, Wang x et al[17−18] believed that in the treatment of the fracture of the neck of humerus, the penetration of ESIN head through the epiphyseal plate of proximal humerus and placement of ESIN in the epiphysis would not cause epiphyseal premature closure and affect the growth. For example, we used ESIN less than 3 mm to penetrate the epiphyseal plate of proximal humerus in some cases, and no epiphyseal premature closure was found in the 3 years follow-up. Due to the mechanism of 4 biological stabilities, the ESIN can exert the effect of stability; the cross stress produced by the nails in the medullary space can attain the goal of supporting the longitudinal axis of the long bone, and avoid the risk of another pathological bone fracture due to weak sclerotin and lesions following focus recurrence (Fig. 6).
Furthermore, we found one of the patients had the lesion in proximal humerus, which was a active ABC. The patient received curettage and bone grafts with high-speed burring and ESIN. According to our 3 years imaging follow-up. we found that there was a focal recurrence, but the focal recurrence migrated away from the epiphysis as time goes on, and the patient had no obstacles in physical exercise so far, whose score of MSTS was 28. In 2008, Patrick et al. retrospectively analyzed 53 patients with ABC, and found that the patients around 12 years old had a relatively high recurrence rate. 8 out of 19 patients with lesion near the epiphysis had recurrence after the surgery and the recurrence rate significantly higher than the patients with ABC in other locations. This study speculated that this might be correlated with insufficient curettage due to surgeon’s concern of postoperative growth deformity during surgery. Therefore, we made a hypothesis that in case of postoperative recurrence, the ESIN in the medullary reduced the risk of pathological fracture, and the patient’s postoperative functional score and life quality were significantly improved to an extent that he/she could even do physical exercise, and when the patient was older and the focus furtherly migrated away from the epiphysis, another surgical treatment was provided, which, according to our speculation, was able to reduce the recurrence rate and surgical difficulty. Furthermore, the patient’s life quality in the recurrence period was greatly improved. This speculation, however, should be further proved by a large amount of clinical cases in the future study (Fig. 7).