1.1 Ethical approval
The study was approved by the ethics committee of General Hospital of Chinese PLA. Informed consents for study inclusion and treatment were obtained from all children parents.
1.2 Inclusion and Exclusion criteria
Inclusion criteria: (1) Age was under 14 years old. (2) Diagnosis was ascertained by imaging of X-ray, CT or MRI. For the suspicious ones, pathological biopsy was performed for an accurate diagnosis. (3) No other treatments before admission were carried out. (4) Guardians coordinated with treatment and follow-up according to the doctor and signed the informed consents.
Exclusion criteria: (1) Complicated with other neoplastic lesions. (2) Pathological fracture occurred in the process of treatment treated by internal and external fixation.
1.3 Criteria for diagnosis
In X-ray plains, simple cyst presents with a round or oval low-density area with mild plumping. Its long axis is mostly parallel to the shaft. bone ridge separation was visible inside the bone cyst. The boundary of the cyst was clear and sharp, and most of them had thin-wall sclerosis edge. Bone debris collapse sign could be found when pathological fracture happens1 13. The therapeutic effect of treatment was evaluated by the criteria of Capanna12 for bone cyst.
1.4 Patients data
From January 2010 to December 2016, 83 children with simple bone cysts were admitted to the department of pediatric orthopedic of PLA general hospital. Twenty-eight cases were treated with ABM, including 16 males and 12 females. The age was 7.7±2.0 years. Ten cases sited on the proximal humerus, eight cases sited on the proximal femur, six cases sited on the proximal tibia and 4 cases on the femoral shaft. Twenty-eight cases were treated with ESIN, including 18 males and 10 females, aged 7.5±3.1 years, including 11 cases of proximal humerus, seven cases of proximal femur, five cases of proximal tibia, four cases of femoral shaft and one case of distal femur. Twenty-seven cases in ABM+ESIN group were treated with ABM combined with ESIN, including 17 males and 10 females, aged 7.7±2.3 years, including 10 cases of proximal humerus, six cases of proximal femur, five cases of proximal tibia, four cases of femoral shaft and two cases of distal femur. There were no statistical significance in the data of age, gender constitution, weight and height among the three groups [Table 1]. All children received preoperative X-ray examination, CT or MRI examination and pathological examination if necessary. All patients were followed up with postoperative X-ray examination.
Table 1 General clinical data in 83 cases among three groups
The data are shown as mean±standard deviation.
1.4 Surgical procedures
ABM Injection14: After anesthesia, the child was routinely sterilized and operating toweled. Before injection, 0.4% lidocaine was used on the bone surface for local anesthesia. Under the guidance of X-ray fluoroscopy, a needle with a core inside was punctured to the bone surface. When the needle tip slowly pierced into the cortex, the needle core was withdrawn. There was light-colored liquid slowly drilled out. Then the needle sheath forwarded with the X-ray guiding to reach the central of the cyst cavity. Next, after local anesthesia of the anterior superior iliac spine, ABM was extracted and slowly injected into the bone cyst cavity. After injection, the puncture needle was removed and the puncture point was covered with sterile dressing.
ESIN Implantation14: After anesthesia, the children were routinely sterilized and sterile toweled. The operation was guided with X-ray fluoroscopy machine. A 0.5 cm incision was made at the epiphysis of the long diaphysis away from the bone cyst. Hemostatic forceps were used for blunt dissection of the subcutaneous tissue to the bone cortex. A cortex drill hole was fulfilled by the nail. The ESIN, pre-bent into a "C" shape, was slowly inserted into the medullary cavity along the drill hole of the bone cortex with the guidance of X-ray fluoroscopy. After the ESIN is properly implanted, bending and cutting the outer portion of the nail for its completely buried subcutaneously. Then the incision is sutured and wrapped with sterile gauze.
ESIN+ABM method: After one to three times of ABM injection with a three-month interval, ESIN implantation was performed.
All cases were given postoperative anti-inflammatory treatment of cefuroxime sodium for two days. The affected limbs were fixed with plaster for six to eight weeks. All cases were encouraged to exercise early after surgery. In cases of lower extremities, in order to avoid pathological fracture, they were encouraged to do weight-free exercise in bed in the early period of recovery.
1.5 Follow-up and indicators for outcome appraisal
Preoperative and Postoperative clinical follow-up and imaging evaluation were performed on all 83 cases. The imaging data, clinical data and treatment results of all 83 children were summarized. The evaluation criteria of Capanna12 for bone cyst were used for outcome appraisal. In the process of evaluation, two experienced clinicians conducted double-blind evaluation. When there was difference in the scores of the same patient, the third specialist participated. The evaluation criteria of Capanna12 for bone cyst: (1) Complete cured: The cyst cavity is completely filled with new bone. No residual lesion is observed. (2) Cured with some residual: Lesion area is mostly replaced by newly growing bone tissue. The mixture of newly growing bone with the surrounding cyst wall bone can be seen. The cyst wall of cortex scleroses and becomes thicker. Residual small transparent areas can be seen in the original cyst site. (3) Recurrence: In the early stage of the treatment, the good effect was observed. Subsequently, transparent areas in the original cyst cavity emerged again. Bone cortex around the cyst becomes thinner. (4) No response: X-ray shows no favorable change and no healing tendency.
The number for effectiveness included the cases of complete cured and cured with some residual. The effective rate was calculated by the proportion of effective cases to the total number of the cases being treated.
1.6 Statistical analysis
SPSS 20.0 statistical analysis software was used for statistical analysis. One-way ANOVA test was used in the analysis data of admission times, age, and height. Kruskal-wallis rank-sum test was used in the analysis of weight, follow-up duration and therapeutic times for cured ones. Chi-square test was used in the analysis of gender composition, effective rate, cure rate and the site of cyst. P<0.05 was considered statistical significance.