Unicameral Bone Cysts: Review of Etiopathogenesis and Current Concepts in Diagnosis and Management

Doxycycline Sclerotherapy of Aneurysmal and Unicameral Bone Cysts in the Appendicular Skeleton and Pelvis: Single-Center 14-Year Experience

PURPOSE

To evaluate the safety, effectiveness, and patient satisfaction of doxycycline sclerotherapy for aneurysmal bone cysts (ABCs) and unicameral bone cysts (UBCs).

MATERIALS AND METHODS

This was an institutional review board (IRB)-approved single-center retrospective review of all ABCs and UBCs of the appendicular skeleton and pelvis completing doxycycline sclerotherapy and having at least 2 years of follow-up from 2007 to 2021. Radiographic outcomes in a patient cohort were assessed with a modified Neer score. Patient-reported outcome (PRO) surveys were completed by a subgroup of the cohort assessing pain after treatment (Likert scale), functional outcomes (Patient-Reported Outcomes Measurement Information System), and overall patient satisfaction (adapted from the Musculoskeletal Tumor Society).

RESULTS

Seventy-seven lesions met the inclusion criteria, with 55 (71%) receiving bone void filler in addition to doxycycline. Of the 77 lesions, 76 (99%) were successfully treated. Twelve lesions (16%) recurred but resolved with additional doxycycline treatment. One lesion failed sclerotherapy, requiring surgical excision. Of the 383 total treatments performed, 17 resulted in Society of Interventional Radiology (SIR)-classified adverse events (9 with Grade 1, 7 with Grade 2, and 1 with Grade 3). Twenty-five (32%) of the 77 cases completed PRO surveys, with 20 (80%) having little to no pain and 15 (60%) having no functional impairment after completing treatment. The PRO surveys documented high levels of satisfaction, with all patients agreeing that they would undergo doxycycline sclerotherapy again if given the option.

CONCLUSIONS

Doxycycline sclerotherapy (with or without bone void filler) is a safe, effective, and well-tolerated stand-alone treatment for ABCs and UBCs.

Surgical Treatment of Proximal Humerus Unicameral Bone Cyst: A Case Report

Unicameral bone cysts (UBCs) are noncancerous, fluid-containing sacs commonly seen in the metaphysis of long bones among young individuals, mainly affecting the proximal humerus and femur. Since they are painless, 80% of patients do not experience any symptoms from UBCs unless it is complicated by a pathological or stress fracture. These patients usually present with no history of trauma, with mild pain, local tenderness, and occasionally swelling. The diagnosis of UBCS can either be an incidental finding or can be made with the help of clinical features, radiographs, and differential diagnoses of UBCs like aneurysmal bone cyst, fibrous dysplasia, enchondroma, eosinophilic granuloma, and intraosseous ganglia can be ruled out. While identifying these cysts is often straightforward, there is ongoing debate regarding the optimal management approach. We report a case of a 16-year-old female with proximal humerus UBC who presented with a pathological fracture of the right proximal humerus. The patient was initially managed conservatively. However, she sustained a refracture at the same site twice over four years. Due to fracture recurrence and residual deformity, it was treated surgically with curettage, bone grafting, and internal fixation. The normal alignment and function of the right upper limb were restored postoperatively.

Pathological fracture increases the risk of unsatisfactory functional results and avascular necrosis in children with proximal femur simple bone cysts

INTRODUCTION

Proximal femur simple bone cysts (SBCs) are rare in children, but with a risk of pathological fractures and the associated poor outcomes. This study aimed to evaluate the functional and radiographic outcomes of children with proximal femur SBCs.

PATIENTS AND METHODS

38 children with proximal femur SBCs treated surgically at our department, West China hospital, were enrolled in the study. Patients were divided into two groups according to whether pathological fractures presented before treatment. The non-fracture group received treatment of open curettage, cavity electrocauterization, bone grafting, and fixation (proximal femoral plate, intramedullary nail or Kirschner wire). The pathological fracture group received the same procedures of curettage, electrocauterization, grafting, and fixation. Autogenous iliac bone grafting was done in all cases, and the artificial bone was used as a supplementary based on the size of the cavity. Postoperatively, all patients underwent hip spica or similar orthosis immobilization for six weeks and received the same rehabilitation program after the removal of hip spica. Patients were evaluated by two independent observers, including the functional results based on the Ratliff's criteria, avascular necrosis, healing rate based on the Neer scoring system, coxa vara, and premature physeal arrest. We described the good outcome in Ratliff's criteria as "Satisfactory results", and fair and poor outcomes as "Unsatisfactory results." Grade 1 and grade 2 Neer results were termed as failures in treatment, and grades 3 and 4 were considered successes and healing.

RESULTS

38 patients with 38 hips (18 on the left side and 20 on the right side) were evaluated, including 9 females and 29 males, with a mean age of 9.0±2.6 years old (range, 5 to 14 years). There was no significant difference between these two groups in the baseline data of gender, age, side, grafting, staging, and fixation methods. The rate of unsatisfactory functional results in the pathological fractures group was 56.3% (9/16), significantly higher than that in patients without fracture (22.7%, 5/22. p= 0.047). There was also a significant difference in avascular necrosis of the femoral head between the pathological fractures group (7/16) and the group without fracture (2/22, p=0.021). Thirty cases presented with healing, including 13 in the fractures group and 17 in the non-fracture group (p=1.000), and eight cases were graded as failures (2 cases of grade 1 and 6 cases of grade 2). There were also no significant differences between these two groups in premature physeal arrest (2 in fracture group and 1 in non-fracture group, P=0.562), and Coxa vara (3 in the fracture group and 0 in non-fracture group, P=0.066).

CONCLUSIONS

Pathological fracture significantly increases the risk of unsatisfactory functional results and avascular necrosis of the femoral head in patients with femoral neck SBCs. Prophylactic treatment and fixation of SBCs in weight bearing proximal femur region is better to manage without complications than managing with pathological fractures.

Percutaneous calcium sulfate injection versus localized scrape bone grafting: clinical effect comparison in titanium elastic nail treatment of pathological fracture of proximal humerus caused by unicameral bone cysts in children

Objective

A retrospective study was conducted to compare the mid-term clinical efficacy between percutaneous calcium sulfate injection (PCSI) and localized scrape bone grafting (LSBG) in using titanium elastic nails treat humerus pathologic fractures caused by unicameral bone cysts in children.

Methods

Humerus pathologic fracture patients with unicameral bone cysts in our pediatric orthopedic department from January 2015 to January 2020 were retrospectively analyzed. Patients were divided into two groups, namely the PCSI group and the LSBG group, based on the type of bone grafting material they received. Preoperative assessments were made in both groups using the Cyst Index and Cyst activity. During the perioperative phase, assessments were made regarding operative time, bleeding, postoperative VAS scores, and the frequency of reoperation within 2 years. Clinical outcomes were evaluated using the Capanna scale at the last follow-up, and the occurrence of re-fractures during the follow-up period.

Results

A total of 22 patients were included, with a mean follow-up duration of 33.5 ± 5.8 months. No significant differences were found between the two groups in terms of Cyst Index and Cyst activity before the operation. The operative time, bleeding, and postoperative VAS scores in the PCSI group were found to be lower than those in the LSBG group (P < 0.05). The PCSI group also showed a higher frequency of reoperation within 2 years compared to the LSBG group (P < 0.05). However, no significant differences were observed between the two groups in terms of Capanna scale scores at the last follow-up and the incidence of re-fractures during follow-up.

Conclusions

Both titanium elastic nails (TEN) combined with PCSI or LSBG were found to be safe and effective treatments for humerus pathologic fractures caused by unicameral bone cysts in children. PCSI is considered as a less invasive option with shorter operative times, less bleeding, and reduced postoperative pain, although it comes with the risk of multiple injections. On the other hand, LSBG is considered as a more invasive option for the treatment of active bone cysts but is associated with a lower recurrence rate.

Long-Term Outcomes of Decompression and Grafting in Acute Pathological Proximal Femur Fractures in Children with Unicameral Bone Cysts: A Retrospective Study Utilizing a 120° Fixed-Angle Low-Contact Locking Pediatric Hip Plate

BACKGROUND Unicameral bone cysts (UBCs) are benign tumor-like lesions that are the most common cause of pathological proximal femur fracture in children. This study aimed to present the outcomes of acute, unstable, pathological proximal femur fractures secondary to UBCs in children. MATERIAL AND METHODS We retrospectively reviewed data on 12 patients with a mean age of 9.3 years (7-12 years) who were initially treated with decompression and grafting, followed by stabilization using a 120° fixed-angle low-contact locking pediatric plate (LCLPP). The Musculoskeletal Tumor Society (MSTS) scores, Capanna classification of cyst repair, time to union, collodiaphyseal angle (CDA), and limb length discrepancy (LLD) were evaluated. RESULTS The mean follow-up was 33.1 months (range, 13-96 months). The mean union time was 9.5 weeks (8-14 weeks). The mean time for reparation of the cyst was 6.9 months (range 3-9 months). Four patients had Dormans type IB, while the remaining had type IIB fractures. According to the Capanna classification, repairs in 10 cases were grade I and in 2 cases grade II. At the last follow-up, the mean 120.8° of preoperative CDA was corrected to 140.9° (P<0.001) and there was no difference compared to the healthy side (P=0.214). The mean postoperative MSTS score was 97.1% (29.1 points). Two patients experienced LLD at the affected extremities, while the other 10 patients healed without any complications. CONCLUSIONS Fixation of acute unstable fractures secondary to UBCs with a 120° fixed-angle LCLPP is a reliable and successful option after decompression and grafting of the lesion.