The role of osteoblast cells in the pathogenesis of unicameral bone cysts

Treatment and Outcomes of 4,973 Unicameral Bone Cysts: A Systematic Review and Meta-Analysis

» Unicameral bone cysts (UBCs) can increase the risk of pathologic fractures of both long and short bones. Although multiple treatments exist, data are conflicting regarding optimal management.

» We sought to analyze treatment strategies for UBCs and their rates of successful treatment.

» Success rates were analyzed according to treatment modality, with emphasis on filling techniques and/or decompression associated with curettage, and injection compounds.

» Curettage with bone substitute and cyst decompression was identified as a highly successful technique for UBC treatment.

» Decompressing the cyst wall after injection, regardless of the specific compound used, had a greater potential to enhance healing rates.

» The management decision should be individually guided within the patient's context.

High tartrate-resistant acid phosphatase (TRACP 5b) level in cystic fluid is a significant prognostic marker for postoperative recurrence in solitary bone cysts

PURPOSE

The pathogenesis of cystic fluid storage in solitary bone cysts remains unclear. We aimed to compare the results of the biochemical analysis of cystic fluid with clinical findings. We identified a significant marker of postoperative recurrence.

METHODS

Twenty-seven male and eight female patients were studied; the median age at diagnosis was 11 (5-23) years. The mean follow-up period was 60 months (range: 14-146 months). Clinical information including sex, age, affected site, radiological findings of phase (active or latent), surgical procedure, outcome, and biochemical analysis of serum and cystic fluid was obtained.

RESULTS

The 5-year healing rate was 64.0%. Biochemical analysis revealed that total protein and albumin values in the cystic fluid were significantly lower, compared to those in the serum. Levels of bone turnover markers, such as alkaline phosphatase, bone-specific alkaline phosphatase, and tartrate-resistant acid phosphatase 5b were remarkably elevated in the cystic fluid than in the serum. R values were 0.127, 0.076, and 0.095 for alkaline phosphatase, bone-specific alkaline phosphatase, and tartrate-resistant acid phosphatase 5b, respectively. Areas under the receiver operating characteristic curves, calculated to assess the association of alkaline phosphatase, bone-specific alkaline phosphatase, and tartrate-resistant acid phosphatase 5b levels in the cystic fluid with postoperative recurrence, were 0.57, 0.51, and 0.70, respectively.

CONCLUSIONS

No clear correlation of bone turnover marker levels between the serum and cystic fluid was observed. The high tartrate-resistant acid phosphatase 5b level in the cystic fluid was associated with postoperative recurrence. The bone resorption caused by osteoclasts is considered to affect postoperative recurrence.

LEVEL OF EVIDENCE

Level IV.

Elastic intramedullary nailing combined with methylprednisolone acetate injection for treatment of unicameral bone cysts in children: a retrospective study

PURPOSE

The aetiology of unicameral bone cysts (UBCs) is unclear. This study aims to evaluate the feasibility of elastic intramedullary nailing (EIN) combined with injections of methylprednisolone acetate (MPA) for the treatment of UBCs in children.

METHODS

We retrospectively analyzed 53 children with UBCs in our hospital between January 2010 and April 2016. A total of 24 patients (Group A) were treated by EIN and MPA, whilst 29 patients (Group B) were treated by curettage, bone grafts and EIN fixation. The radiographs of the UBCs were evaluated following the Capanna criteria. All patients were followed-up on the third, sixth, 12th, 24th and 36th months. Fixation time, hospitalization time and complications were evaluated.

RESULTS

In Group A, the mean number of MPA injections was 1.8 (1 to 3). Based on radiographic evaluation, eight patients were healed (Capanna grade I), 14 were healed with residual cysts (Capanna grade II), one showed recurrence (Capanna grade III) and one showed no response to the treatment (Capanna grade IV). In Group B, 11 patients were evaluated as Capanna grade I, 12 as Capanna grade II, three as Capanna grade III and three as Capanna grade IV. There was significant difference in the early postoperative function activity (p < 0.001), hospitalization time (p = 0.028), blood loss during surgery (p < 0.001) and surgery time (p < 0.001).

CONCLUSION

The combination of EIN and MPA for the treatment of UBCs in children is feasible, has little operative trauma, short surgery time, short hospitalization time, less blood loss and a low risk of incision infection.

LEVEL OF EVIDENCE

III.

Synthetic Bone Graft Substitute for Treatment of Unicameral Bone Cysts

BACKGROUND

Treatments for unicameral bone cysts (UBCs) have high documented failure rates (27% to 63%) because of recurrence or persistence of the cyst, similar to nonoperative management. Recent evidence suggests that filling of the defect with a synthetic bone graft substitute (SBGS) supports the weakened cortex and promotes new bone growth. A calcium sulfate, brushite, calcium phosphate, composite graft material (PRODENSE, Wright Medical, Memphis, TN) has been evaluated as a substitute for autogenous or allogenous graft in animal and human studies. The purpose of this study was to compare the rates of revision surgery in patients treated for UBCs with an SBGS compared with historical treatments with allograft or autologous bone marrow aspirate.

METHODS

The authors reviewed 27 of 33 patients (age, 6 months to 21 years) an average of 121 months (range, 32 to 228) after filling of a UBC with an injection of SBGS (n=18) versus allograft or autologous bone marrow aspirate (n=9) between June 2008 and December 2017. Six patients with no follow-up were excluded. Groups did not differ in age at surgery, sex (19/27 male), history of pathologic fracture (22/27), or previous treatments (11/27). The primary outcome was the rate of revision surgery. Secondary outcomes included revision surgery-free survival as evaluated by the log-rank test, rate of postoperative fracture, persistent cysts, continued pain, and/or growth disturbance at the final follow-up.

RESULTS

Seven of 9 patients treated with allograft or autograft underwent revision surgery for postoperative pathologic fracture (n=2) or resorption of the graft (n=5) compared with 2 of 18 patients injected with the SBGS, both treated for graft resorption. The use of SBGS was associated with a decreased need for revision surgery over all time periods (hazard ratio, 0.14; 95% confidence interval, 0.03-0.05). There was no significant difference between postoperative fracture (2/18 vs. 2/9), persistent cyst (7/18 vs. 5/9), pain (0/18 vs. 2/9), or growth disturbance (1/18 vs. 3/9).

CONCLUSIONS

Treatment of UBCs with SBGS may decrease reoperation rates. Initial radiographic appearance after SBGS treatment shows solid structural support, followed by new bone formation. This appearance may lead to a less aggressive approach in considering revision surgery.

LEVEL OF EVIDENCE

Level III-retrospective comparative study investigating the results of treatment.

Possible pathogenesis of calcaneal bone cysts

INTRODUCTION

Recent literature indicates that calcaneal bone cysts have different clinical features compared to long bone cysts. Yet, previous studies have mainly focused on pathogenesis of long bone cysts. In this study, the pathogenesis of calcaneal bone cysts was investigated from radiological and pathological findings.

MATERIALS AND METHODS

Patients comprised 18 males and 6 females diagnosed with calcaneal bone cysts at a median age ± standard deviation of 13.0 ± 3.6 years. Plain radiographs, computed tomography, magnetic resonance imaging, cystography, bone scintigraphy, and pathology were reviewed.

RESULTS

All cysts occupied the central triangular area of the bone, with six extending posteriorly and two developing anteriorly. Fifteen of 20 cases (75%) showed the expanded foramen structures at the anterior margin of the posterior facet. According to cystography, four cysts showed absence of leakage to subtalar joint. Cystic fluid caused chronic haemorrhaging in 18 cases and pathologically detected cholesterol clefts were noted in 14 cases.

DISCUSSION

The location of the expanded foramen structures was consistent with the nutrient foramens of the sinus tarsi artery in the unaffected population. Hence, initial cysts may originate from the collapse of the sinus tarsi artery. Subsequent haemorrhage may extend into the central triangle area, which is biomechanically free of stress. Because of poor bone remodelling, degenerative change of the haemorrhage is prolonged. The results of this study showed that circulation collapse of the sinus tarsi artery and mechanical factors are important in the formation of calcaneal bone cysts.

An unusual case of proximal humeral simple bone cyst in an adult from secondary cystic change

Background

Simple bone cysts (SBC) have been documented to occur in adults with closed physeal plates, most commonly affecting the calcaneus in this patient subset. Although most authors theorize an association to trauma, etiology of simple bone cysts remains an enigma up to now.

Case presentation

A 26-year-old kickboxing coach sought consult for a painful right shoulder which on radiographs and magnetic resonance (MR) imaging showed a proximal humeral lesion with signs of ossification. The patient was lost to follow-up but again sought consult after 3 years for the recurring complaint. On repeat radiographs, computed tomography (CT) scan, and MR images, tumor enlargement with cystic findings typical of simple bone cyst were documented. Diagnostic aspiration of the lesion was firstly done, revealing straw-colored fluid. The patient then underwent intralesional curettage with alpha-tricalcium phosphate cement reconstruction of the lytic defect. No perioperative complications were incurred, and on latest follow-up at 3 years postoperatively, Musculoskeletal Tumor Society (MSTS) and visual analog scale (VAS) pain scores were 30/30 and 0/10, respectively.

Conclusions

The authors believe their report provides support to a possible association to trauma of simple bone cysts occurring in the adult population with closed physes and suggest this subset of patients may require a different treatment approach from that for juvenile simple bone cysts.

Investigating a potential biological treatment to prevent pathological fractures caused by unicameral bone cysts in children under 8 years

INTRODUCTION

There is no consensus on when and how to treat unicameral bone cysts (UBCs), partly because of a lack of knowledge of the aetiology.

PURPOSE

To review the different treatment techniques for UBCs and to describe our results with a single injection of autogenous bone marrow (BM) mixed with demineralised bone matrix (DBM) in very young children.

PATIENTS AND METHODS

We reviewed five patients under the age of 8 years with UBCs treated by percutaneous aspiration and a single injection of BM associated with DBM. The cyst was located in the proximal humerus in four patients and in the proximal femur in one patient. Assessment of the need for surgery was based on the clinical and radiographic suspicion of new pathological fractures. The administration of a second injection, when necessary, was based on the surgeon's judgement regarding the risk of fracture. The mean follow-up after first injection was 41 months.

RESULTS

There were no complications related to the procedure, except a non-displaced fracture, which healed without problems. All patients were pain free and progressively resumed their activities without restriction until a new fracture occurred in two cases. According to Capanna's classification, only one case healed completely (grade 1), one lesion was classified as grade 2, and there were three recurrences at 11, 12 and 27 months after initial treatment (grade 3). The final outcome was treatment failure for three out of the five patients. Two patients were treated with a second injection and one patient is waiting for surgery.

CONCLUSION

A single injection of aspirated autogenous BM mixed with DBM in very young children with active UBCs at risk of fracture is very simple, comfortable and safe. Nevertheless, the results seem to be unpredictable and are probably more dependent on the natural evolution of the cyst than on the treatment. Further comparative studies with larger sample numbers are needed.