Increased concentrations of nitrate and nitrite in the cyst fluid suggesting increased nitric oxide synthesis in solitary bone cysts

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.

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.

[Benign tumours and tumour-like lesions of the bone : General treatment principles]

BACKGROUND

Benign bone lesions are much more common than malignant lesions. Some benign bone tumors have a characteristic and typical radiographic appearance, while others are more challenging. Therapy of benign bone tumors differs greatly. While the majority of benign bone tumors do not require surgical therapy, other specific lesions, e. g. aneurysmal bone cysts or giant cell tumors (GCT) of the bone require surgery due to their locally aggressive behavior.

DIAGNOSTICS

The major challenge for the radiologist and/or pathologist is the differentiation between a benign and low-grade malignant lesion (e. g. enchondroma versus low-grade chondrosarcoma) for which all available clinical and radiographic information is mandatory. Therefore, surgical therapy is rather more often performed than necessary due to uncertainty in many cases.

THERAPY

Novel systemic therapies are available for fibrous dysplasia and GCT of the bone: Fibrous dysplasia can be treated with bisphosphonates, and GCT responds to denosumab. In fact, denosumab has been approved for the treatment of irresectable GCT. Osteoid osteoma is fairly easy to recognize and also to treat given the characteristic clinical presentation and rapid and effective response to local therapy (possible as percutaneous thermo-/laser ablation). In summary, several therapeutic options exist for benign bone tumors, and the choice depends upon the tendency/risk of local recurrence, the rate of surgical complications, options for defect reconstruction, postoperative functional deficits, and specific patient characteristics.

Pronounced femur malunion after pathological bone fracture due to a simple bone cyst in the shaft of the femur, treated using Ilizarov fixation: a case report

Background

Although a simple bone cyst carries the risk of pathological fractures, it rarely causes severe deformity. Here we report a case of severe femoral deformity after multiple pathological fractures due to simple bone cysts, and consider the reason for the progression of malunion despite multiple previous treatments. Finally, we propose a treatment option for malunion correction.

Case presentation

A 9-year, 7-month-old Japanese girl was referred to our facility with obvious deformity of her right femur, caused by multiple simple bone cyst-related pathological fractures. The deformity included bowing of approximately 90° and an internal rotation of 60° in the middle third of the femoral shaft. To correct this deformity, we excised the lesion, thus shortening the femur, then corrected the alignment and applied an Ilizarov fixator to extend the bone. At present, 3 years after surgery, the deformity has not recurred and our patient is living without any limitations in daily activities or regular exercise.

Conclusions

When a long bone is in a prolonged state of deformation, the deformity not only progresses as the bone grows, but the soft tissues remain unbalanced and treatment becomes increasingly difficult. To prevent increasing bone deformity and fragility, the deformity should be corrected as quickly as possible using intramedullary nailing or other fixation techniques. We believe that our shortening-distraction method is effective for the treatment of severe deformity with unbalanced soft tissues.

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.

Predictive characteristic of simple bone cyst treated with curettage and bone grafting

BACKGROUND

The efficiency of treating simple bone cyst (SBC) is low. Depending on the choice of treatment, a positive response occurs in 20 to 80 % of cases. These rates are unacceptable, particularly considering they concern the treatment of benign lesions affecting children. Although cyst curettage is one of the first known ways of treating SBC, no precise qualification criteria exists for this procedure. The aim of our study is to identify which type of cyst may be most effectively treated using curettage with grafting.

METHODS

A retrospective analysis was performed on 24 patients referred to our clinic for SBC treatment. To identify predictive factors, the group of patients who positively responded to treatment (Neer stages I and II, n = 14) were compared with the group in which recurrences occurred (Neer stages III and IV, n = 10).

RESULTS

Significantly fewer patients with lesions located in the humerus (chi(2) = 9.351; p < 0.05) and without pathological facture at the time of diagnosis (p = 0.017) were found in the group with no recurrence. The following radiological parameters were found to vary significantly between groups: cyst area (z = 3.121; p < 0.01), cyst index (z = 2.213; p < 0.05) and cyst diameter ratio (z = 2.202; p < 0.05). In the group with no recurrences, the mean values of these parameters were found to be lower than in group with poor response to treatment. No statistically significant differences regarding age, sex or type of bone graft (p > 0.05) were found. Recurrences were experienced by 10 patients (41.7 %) during the 3-year period after surgery

CONCLUSION

In the group treated with curettage, associations were identified between worse treatment results and the location in the humerus, pathological fractures at the time of diagnosis, large cyst area, large cyst index and large cyst diameter.

[Benign cystic bone lesions]

BACKGROUND

Bone cysts are benign tumor-like lesions which often present as a fluid-containing cavity in the bone. They can occur in the skeletal bone as solitary or sometimes multiple bone lesions.

OBJECTIVES

This review discusses the diagnostics, radiological appearance and therapeutic strategies of the most important benign cystic bone lesions, such as simple bone cysts, aneurysmal bone cysts, intraosseous ganglia, epidermoid cysts and subchondral cysts. The differential diagnoses with respect to cystoid formations and tumors with cystic components are discussed.

METHOD

A selective literature search was performed taking own experiences into consideration.

RESULTS

These tumor-like lesions can have the radiological appearance of bone tumors but show no autonomic, stimulus-independent growth and can resolve spontaneously. In the majority of cases open biopsy is necessary to confirm the diagnosis. In some cases no surgical intervention is necessary (e.g. do not touch and leave me alone lesions), whereas in other cases the focus of treatment is on the prevention and therapy of pathological fractures as well as prevention of recurrence.

CONCLUSION

Cystic bone formations are among the most commonly occurring non-traumatic bone lesions. To eliminate differential diagnostic unclarity, histological investigation of biopsy material is essential. In terms of surgical intervention there exists a trend towards multimodal therapy mostly based on a meticulous curretage.

Treatment of unicameral bone cyst: systematic review and meta analysis

PURPOSE

Different treatment modalities have been utilized to treat unicameral bone cyst (UBC), but evidence has not been fully described to support one treatment over another and the optimal treatment is controversial. The aim of this quantitative systematic review was to assess the effectiveness of different UBC treatment modalities.

METHODS

We utilized Pubmed to isolate retrospective studies on patients with UBC who received any kind of treatment. The included studies needed to have a minimum sample size of 15 patients, and have provided data on radiographic healing outcome.

RESULTS

Sixty-two articles were selected for the meta-analysis from a total of 463 articles. The cumulative sample size was 3,211 patients with 3,217 UBC, and male to female ratio was 2.2:1. The summary or pool estimate of methylprednisolone acetate (MPA) injection resulted in a healing rate of (77.4 %) that was comparable to bone marrow injection (77.9 %). A higher healing rate was observed with MPA injection when inner wall disruption was performed. The pool estimate of bone marrow with demineralized bone matrix injection was high (98.7 %). UBC healing rate after surgical curettage was comparable whether autograft or allograft was utilized (90 %). UBC treatment with flexible intramedullary nails without curettage provided almost 100% healing rate, while continuous decompression with cannulated screws provided 89 % healing rate. Conservative treatment indicated a healing rate of 64.2, 95 % CI (26.7-101.8).

CONCLUSIONS

Active treatment for UBC provided variable healing rates and the outcomes were favorable relative to conservative treatment. Due to the heterogeneity of the studies and reporting bias, the interpretation of these findings should be handled with caution.

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

PURPOSE

The pathogenesis of unicameral bone cysts (UBCs) remains largely unknown. Osteoclasts have been implicated, but the role of osteoblastic cells has, to date, not been explored. This study investigated the pathophysiology of UBCs by examining the interactions between the cyst fluid and human bone marrow stromal cells (hBMSCs) and the effect of the fluid on osteogenesis.

METHODS

Fluid was aspirated from two UBCs and analysed for protein, electrolyte and cytokine levels. Graded concentrations of the fluid were used as culture media for hBMSCs to determine the effects of the fluid on hBMSC proliferation and osteogenic differentiation. The fibrocellular lining was analysed histologically and by electron microscopy.

RESULTS

Alkaline phosphatase (ALP) staining of hBMSCs that were cultured in cyst fluid demonstrated increased cell proliferation and osteogenic differentiation compared to basal media controls. Biochemical analysis of these hBMSCs compared to basal controls confirmed a marked increase in DNA content (as a marker of proliferation) and ALP activity (as a marker of osteogenic differentiation) which was highly significant (p < 0.001). Osteoclasts were demonstrated in abundance in the cyst lining. The cyst fluid cytokine profile revealed levels of the pro-osteoclast cytokines IL-6, MIP-1α and MCP-1 that were 19×, 31× and 35× greater than those in reference serum.

CONCLUSIONS

Cyst fluid promoted osteoblastic growth and differentiation. Despite appearing paradoxical that the cyst fluid promoted osteogenesis, osteoblastic cells are required for osteoclastogenesis through RANKL signalling. Three key cytokines in this pathway (IL-6, MIP-1α, MCP-1) were highly elevated in cyst fluid. These findings may hold the key to the pathogenesis of UBCs, with implications for treatment methods.

Vascularized the greater trochanter grafting treatment cysts of the femoral neck

Bone cyst is a common benign bone tumor lesion, it is characterized by a clear boundary appearing round or oval osteolytic area, cortical bone thinning, and sometimes it can be visible sclerotic margin. Limb long bone cysts occur more common shares, the current jaw bone cysts are also relatively common, and most patients are asymptomatic. Femoral neck bone cyst can lead to pain and pathologic fractures, which is one of the main reasons why patients are in treatment. Due to the lesion site and patients age specificity of femoral proximal bone cysts especially femoral neck bone cysts in young adults, treatment is necessary to completely remove the lesion to prevent cyst recurrence, but also as far as possible to restore function in patients with hip joint.

Mid- and long-term clinical results of surgical therapy in unicameral bone cysts

Background

Unicameral (or simple) bone cysts (UBC) are benign tumours most often located in long bones of children and adolescents. Pathological fractures are common, and due to high recurrence rates, these lesions remain a challenge to treat. Numerous surgical procedures have been proposed, but there is no general consensus of the ideal treatment. The aim of this investigation therefore was to study the long-term outcome after surgical treatment in UBC.

Methods

A retrospective analysis of 46 patients surgically treated for UBC was performed for short and mid-term outcome. Clinical and radiological outcome parameters were studied according to a modified Neer classification system. Long-term clinical information was retrieved via a questionnaire at a minimum follow-up of 10 years after surgery.

Results

Forty-six patients (17 female, 29 male) with a mean age of 10.0 ± 4.8 years and with histopathologically confirmed diagnosis of UBC were included. Pathological fractures were observed in 21 cases (46%). All patients underwent surgery for UBC (35 patients underwent curettage and bone grafting as a primary therapy, 4 curettage alone, 3 received corticoid instillation and 4 decompression by cannulated screws). Overall recurrence rate after the first surgical treatment was 39% (18/46), second (17.4% of all patients) and third recurrence (4.3%) were frequently observed and were addressed by revision surgery. Recurrence was significantly higher in young and in male patients as well as in active cysts. After a mean of 52 months, 40 out of 46 cysts were considered healed. Prognosis was significantly better when recurrence was observed later than 30 months after therapy. After a mean follow-up of 15.5 ± 6.2 years, 40 patients acknowledged clinically excellent results, while five reported mild and casual pain. Only one patient reported a mild limitation of range of motion.

Conclusions

Our results suggest satisfactory overall long-term outcome for the surgical treatment of UBC, although short-and mid-term observation show a considerable rate of recurrence independent of the surgical technique.