Calcaneal cyst: a classical simple bone cyst?

INTRODUCTION: In the calcaneus differentiation between a solitary cyst and intraosseus lipoma is difficult. Radiologists frequently diagnose an intraosseus lipoma, whereas histology shows the classical signs of a solitary bone cyst. We present 12 cases of a solitary cyst of the calcaneus. MATERIAL AND METHODS: Between 1993 and 2001 we operated on 12 patients (8 men, 4 women, median age 28 +/- 14 years) with calcaneal cysts. 9 patients received a curretage and an autologous, one patient a homologous, one patient a mixed autologous-homologous bone-grafting and one patient only a curretage (due to the small diameter of the cyst) of their cysts. RESULTS: No case revealed the histological picture of a fatty formation, which appears to be typical for an intraosseus lipoma. All of the microscopic findings resembled the characteristics seen in cysts of the long bones. A pathological fracture has not been observed. CONCLUSION: The histologically confirmed calcaneal cysts showed the radiological signs that are supposed to be typical for an intraosseous lipoma. It cannot be decided whether the histologically diagnosed calcaneal lipomas described by others can be interpreted as fatty degeneration of a calcaneal cyst, or whether fatty areas of the bone marrow have given a wrong impression. Since the literature only describes single isolated cases of a pathological fracture of the calcaneal cyst or lipoma, asymptomatic patients should be treated non-operatively.     

Spontanheilung einer juvenilen Knochenzyste der Tibia nach pathologischer Fraktur

Up to the present only few cases of spontaneous healing of juvenile bone cysts after pathological fractures were published. Most authors will not accept the possibility of a "healing fracture" in bone cysts because of missing documentation. In our clinic we could observe spontaneous healing of a juvenile bone cyst of the tibia after a pathological fracture in a ten-year old boy. Therefore healing of bone cysts after fracture is proven. On the other hand healing of bone cysts following conservative treatment after a fracture is not sure. Conservative treatment depends on the localization and type of the fracture. We recommend nonoperative treatment of first pathological fractures in small-sized bone cysts. This kind of treatment can be especially advised for young patients up to the tenth year because there are only few complications in fracture healing and a relatively high recurrence rate following operative treatment. In case of a refracture there are better conditions for fracture healing after surgery.     

Autologous bone marrow injection in the management of simple bone cysts in children

The majority of simple bone cysts (SBC's) is not symptomatic and remains undiagnosed or is discovered fortuitously. A number of simple bone cysts are only diagnosed after a pathological fracture which occurs as a presenting symptom. Fractures are managed either conservatively or surgically, based on criteria such as the age of the child and the type and localisation of the fracture. The risk for fracture can be evaluated radiographically. In the absence of a fracture risk, plain radiographic follow-up is sufficient. In case of a high fracture risk, percutaneous aspiration and injection of bone marrow may be performed. The result of this treatment in 21 simple bone cysts with a high risk for fracture is reported. Slow regression of the cyst and progressive healing were obtained in 15 cases (71.4%) whereas no response was noted in 3 cases (14.3%) and recurrence in another 3 (14.3%), after a mean follow-up of 37.1 months. Guidelines are proposed for the follow-up and management of SBC.     

异体长骨干移植修复四肢骨囊肿合并病理性骨折

目的观察移植异体长骨干、骨板及钢板内固定治疗四肢骨囊肿合并病理性骨折的疗效. 方法 1996年1月～2002年4月,临床共收治12例四肢骨囊肿合并病理性骨折患者,囊肿4 cm×6 cm～3 cm×13 cm,平均3.6 cm×8.1 cm.切除囊肿前壁,刮除囊膜,植入经脱脂、脱蛋白的异体腓骨干或尺、桡骨干,用钢板或加对侧皮质贴附骨板,将自体骨、异体骨连成一体固定;术后外固定3周. 结果 12例术后伤口无红肿及渗液发生,均Ⅰ期愈合.随访1～4年,平均2.7年.骨囊腔愈合情况根据Capanna等评定标准进行评估,愈合9例,基本愈合3例;无复发,无不良反应发生.2例肱骨上段骨囊肿术后肩关节功能轻度受限,余10例患肢功能均恢复正常. 结论异体长骨干移植是修复四肢骨囊肿合并病理性骨折的安全、有效方法.     

Flexible intramedullary nailing for unicameral cysts in children’s long bones

Purpose  The purpose of this study was to evaluate the outcome of flexible intramedullary nailing for unicameral bone cysts in terms of function and osseous consolidation. Methods  Twenty-two unicameral bone cysts in children’s long bones were treated by flexible intramedullary nailing. In 13 cases the bone cyst was diagnosed in a traumatic event leading to a pathologic fracture. Fifteen patients were referred to our clinic after failed conservative treatment. In 16 patients the cyst was located in the humerus, and in 6 patients in the femur. Mean duration of follow-up after surgery was 24 months. Results  According to Capanna’s criteria healing was obtained in 20 cases with a mean time of 16 months. Sixteen cysts healed completely. Four lesions were classified as grade 2, meaning that residual radiolucencies were radiographically visible at the latest follow-up. Two recurrences of humeral cysts were seen at 16 and 18 months postoperatively. The complication rate was minimal. Conclusion  Due to the immediate stabilization of the lesion aftercare becomes facile. This method allows prompt mobilization and early weight bearing without the necessity of a plaster cast. Further it prevents effectively the most common complication, a re-fracture or a pathologic fracture. Therefore we propose this surgical procedure as the treatment of choice for unicameral bone cysts in children’s long bones. No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. No funds were received in support of this study. M. C. Glanzmann is AO Intl. Fellow     

Fracture pathologique du scaphoïde carpien (kyste synovial intraosseux). Aspect clinique et thérapeutique. À propos d’un cas

The authors report a case of fracture of the carpal scaphoid through an intraosseous synovial cyst. Synovial cysts are not uncommon in the carpal region, and are usually discovered as an incidental radiological finding: they rarely present with wrist pain and only exceptionally as a fracture. In our knowledge, only one other case of intraosseous synovial cyst of the carpal scaphoid presenting as a fracture has been published. Surgical treatment of these benign tumors, in cases of fracture or painful symptoms, consists of curettage of the lesion followed by impaction grafting of cancellous bone combined with stabilization in the case of a fracture. The use of a vascularized bone graft pedicled on the volar carpal artery enables simultaneous treatment of both the cyst and the fracture. The prognosis is good and relapse is exceptional.     

Diagnosing aneurysmal and unicameral bone cysts with magnetic resonance imaging

The differential between aneurysmal bone cysts and unicameral bone cysts usually is clear clinically and radiographically. Occasionally there are cases in which the diagnosis is not clear. Because natural history and treatment are different, the ability to distinguish between these two entities before surgery is important. The authors reviewed, in a blinded fashion, the preoperative magnetic resonance images to investigate criteria that could be used to differentiate between the two lesions. All patients had operative or pathologic confirmation of an aneurysmal bone cyst or unicameral bone cyst. The authors analyzed the preoperative magnetic resonance images of 14 patients with diagnostically difficult bone cysts (eight children with unicameral bone cysts and six children with aneurysmal bone cysts) and correlated these findings with diagnosis after biopsy or cyst aspiration and contrast injection. The presence of a double density fluid level within the lesion strongly indicated that the lesion was an aneurysmal bone cyst, rather than a unicameral bone cyst. Other criteria that suggested the lesion was an aneurysmal bone cyst were the presence of septations within the lesion and signal characteristics of low intensity on T1 images and high intensity on T2 images. The authors identified a way of helping to differentiate between aneurysmal bone cysts and unicameral bone cysts on magnetic resonance images. Double density fluid level, septation, and low signal on T1 images and high signal on T2 images strongly suggest the bone cyst in question is an aneurysmal bone cyst, rather than a unicameral bone cyst. This may be helpful before surgery for the child who has a cystic lesion for which radiographic features do not allow a clear differentiation of unicameral bone cyst from aneurysmal bone cyst.     

The surgeon's procedure in dystrophic bone cysts in children]

The authors set apart childhood dystrophic cyst as a separate nosological unit. The underlying factor of the development of a bone cyst is dysplasia of vessels filling the bone-marrow canal and a concomitant dystrophic process in the surrounding bone tissue. The nonneoplastic nature of the cysts led to the search for sparing methods of treatment, namely, the puncture method. The administration of demineralized bone shavings during therapeutic puncture (after osteoperforation of the wall, scraping off the fibrous membrane) produces good results. The clinical material consists of 46 cases. There were 8 cases of aneurysmal bone cyst, 23 with active and 15 with passive bone cysts. In 44 cases treatment by two or three punctures led to recovery in 2-4 months. In 2 patients with aneurysmal bone cysts three punctures proved ineffective and an operative intervention was undertaken. It is concluded that treatment by puncture is indicated in dystrophic bone cysts. Operation is indicated in poor outcomes of puncture treatment in patients with aneurysmal bone cysts.     

Old fibrin coagula and their ossification in simple bone cysts.

Old calcified fibrin coagula are frequently found in simple bone cysts. They provide a scaffold on which new bone is laid down, in a process analogous to endochondral ossification. It is suggested that these coagula are derived in substantial part from the plasma-like contents of the cyst, after the release of plasma-clotting factors as the result of injury. Major haemorrhage is not involved and in many cases there is no antecedent fracture. The phenomenon is not seen in other common cystic conditions of bone and its recognition is thus helpful in the histological diagnosis of simple bone cyst. Cystic bone infarcts and their possible confusion with simple bone cysts are also briefly discussed.     

The value of homologous spongiosa in en-bloc resection of juvenile bone cysts of the upper arm

The recurrence rate after excochleation and homogeneous bone grafting of juvenile and aneurysmal bone cysts is high. One of the reasons is the poor vascularisation of the wall of the cyst. En-bloc resection is recommended in cases of recurrence after curettage and bone grafting and in cases of prior conservative treatment after pathological fracture followed by a rapid growth of the cyst. Excellent results of en-bloc resection in 8 cases of humerus bone cyst are reported. Good vascularisation of the juvenile periosteum and the surrounding soft tissue is most important for new bone formation after homogeneous bone grafting.     

Cyst index: a nonpredictor of simple bone cyst fracture

PURPOSE: Treatment is indicated for simple bone cysts (SBC) with high risk of fracture. The cyst index was described as a method to determine if a cyst is at high risk or low risk of fracture. STUDY DESIGN: The cyst index of 32 femoral and humeral SBCs was determined by 8 reviewers. The risk group cyst index was compared with whether a fracture took place. Sensitivities, specificities, and positive and negative predictive values were calculated across varying cutoff levels. Intraobserver and interobserver reliability testing for 10 cysts was made. RESULTS: Receiver operator curves demonstrate that no cutoff value gave an acceptable level of both sensitivity and specificity. The mean value for the cyst index was significantly different for different observers (P < 0.05). CONCLUSIONS: This study does not validate the cyst index to be an accurate predictor of fracture. The test has low intraobserver and interobserver reliability. CLINICAL RELEVANCE: The cyst index cannot reliably discriminate between the patients that will fracture and those that will not.     

GROWTH DISTURBANCES ASSOCIATED WITH UNTREATED BENIGN BONE CYSTS

Background: The occurrence of benign bone cysts adjacent to an active physis may be associated with a physeal arrest. That arrest may result from physeal penetration of the cysts itself, secondary pathologic fracture or the result of surgical curettage. Methods : The pre-treatment X-rays of patients attending the Bone Tumor Clinic at the Children's Hospital and Medical Center were reviewed. Those patients presenting with a bone cyst were identified and the affected side was compared to the normal side in order to determine growth discrepancies. Results: Three cases of benign bone cysts are presented that were located adjacent to a growing physis and produced growth disturbance in the absence of surgical intervention. Conclusions: The risk of growth disturbance in itself should not be a contraindication to surgical intervention.     

Unicameral bone cysts in the humerus and femur in the same child

Although simple bone cysts in children have been described by many authors, there has been only one previous report of more than one lesion in a single patient. We describe an 11-year-old boy with symptoms caused by a cyst in the proximal femur. Following steroid injection of the cyst, a pathological fracture occurred and was treated by immobilization in a cast. A year later, a pathological fracture occurred through a cyst in the proximal humerus. This was treated in a sling. Steroid injection of both lesions was performed when the cystic areas persisted, and both cysts subsequently healed. This case demonstrates that simple bone cysts are not always solitary lesions and that patients with these cysts should be carefully monitored for recurrence following treatment.     

Clinical relevance of calcaneal bone cysts: a study of 50 cysts in 47 patients

The clinical relevance and nature of calcaneal cysts is controversial. The risk of pathologic fracture is undefined and diagnostic criteria to differentiate between cysts in patients who can be treated nonoperatively and patients who require surgical intervention are not available. To address these questions, 50 calcaneal bone cysts in 47 patients were evaluated. The majority of cysts (40 of 50) were asymptomatic and were treated nonoperatively. Cysts reaching a critical size, defined as 100% intracalcaneal cross section in the coronary plane and at least 30% in the sagittal plane, are at risk for becoming symptomatic and at risk for fracture. Fracture is a significant complication and occurred in four of 47 patients, three of whom were treated by open reduction internal fixation and bone grafting. In addition, six patients with symptomatic critical size cysts without apparent fracture were treated by curettage and subsequent autogenous bone grafting or calcium-phosphate cement filling, and there were no recurrences. We report one of the largest series of cysts in the calcaneus. The results suggest that calcaneal cysts are clinically relevant because of the potential risk of fracture and that size is a significant factor in terms of the treatment of the cyst.     

Treatment of active unicameral bone cysts with percutaneous injection of demineralized bone matrix and autogenous bone marrow

BACKGROUND: The treatment of unicameral bone cysts varies from open bone-grafting procedures to percutaneous injection of corticosteroids or bone marrow. The purpose of this study was to evaluate the feasibility and effectiveness of percutaneous injection of a mixture of demineralized bone matrix and autogenous bone marrow for the treatment of simple bone cysts. METHODS: Twenty-three patients with an active unicameral bone cyst were treated with trephination and injection of allogeneic demineralized bone matrix and autogenous bone marrow. The patients were followed for an average of fifty months (range, thirty to eighty-one months), at which time pain, function, and radiographic signs of resolution of the cyst were assessed. RESULTS: The average time until the patients had pain relief was five weeks, and the average time until the patients returned to full, unrestricted activities was six weeks. Bone-healing at the site of the injection was first seen radiographically at three to six months. No patient had a pathologic fracture during this early bone-healing stage. Cortical remodeling was seen radiographically by six to nine months, and after one year the response was usually complete, changing very little from then on. Five patients required a second injection because of recurrence of the cyst, and all five had a clinically and radiographically quiescent cyst after an average of thirty-six additional months of follow-up. Seven of the twenty-three patients had incomplete healing manifested by small, persistent radiolucent areas within the original cyst. None of these cysts increased in size or resulted in pain or fracture. CONCLUSIONS: Percutaneous injection of allogeneic demineralized bone matrix and autogenous bone marrow is an effective treatment for unicameral bone cysts.     

Flexible intramedullary nailing for the treatment of unicameral bone cysts in long bones

BACKGROUND: Unicameral bone cyst is characterized by its tenacity and risk of recurrence. Pathological fracture is common and is often the presenting symptom. The objective of the present study was to evaluate the results of flexible intramedullary nailing for the treatment of a unicameral bone cyst with or without a pathological fracture. METHODS: Flexible intramedullary nailing for the treatment of a unicameral bone cyst was performed in thirty-two patients. Thirty of these patients presented with a pathological fracture; twenty-four were managed immediately with intramedullary nailing, and the other six had been managed conservatively at other clinics before they were referred to our department. The remaining two cysts were detected incidentally. The cyst was located in the humerus in twenty-one patients, in the femur in nine, and in the radius in two. The mean age of the patients at the time of surgery was 9.8 years, and the mean duration of follow-up was 53.7 months. Radiographic evaluation was performed according to the criteria of Capanna et al., and the cyst was classified as completely healed, healed with residual radiolucency (osteolysis), recurred, or having no response. RESULTS: The healing period ranged from three to 105 months. Fourteen cysts healed completely, and sixteen healed with residual radiolucent areas visible on radiographs. There was recurrence of two cysts that had healed with residual radiolucency. All of the cysts in the present study responded to treatment. A change of nails was necessary in nine patients, as the nails had become too short after bone growth. No major complications were observed. CONCLUSIONS: Flexible intramedullary nailing provides early stability, which allows early mobilization and thus obviates the need for a plaster cast and decreases the prevalence of the most common complication: a pathological fracture. This method of treatment also allows for an early return to normal activity.     

Early management of pathological fractures in children

The management of pathological fractures in children remains controversial. The indications for surgical treatment are unclear and the need for histological diagnosis before or after definitive treatment is not clearly defined. We reviewed retrospectively the records of all patients under the age of 16 years who presented over the past 7 years with a fracture as the first manifestation of bone pathology. There were 23 patients (16 boys and 7 girls) of an average age of 12 years and 2 months (range 4.1-15.8 years). There were nine cases of fracture through a simple bone cyst, five cases of fibrous dysplasia, two giant cell tumours, three aneurysmal bone cysts, one chondroblastoma, and three cases of Ewings sarcoma. After review of our cases we propose a simple algorithm for the safe early management and assessment of paediatric pathological fractures. We recommend that primary fixation of pathological fractures should be avoided until histological diagnosis is obtained. Most lesions should eventually be biopsied. However, if radiographic appearances are reassuringly benign, biopsy can be delayed until conservative fracture management is completed. Definitive treatment of benign lesions with protective intra medullary nailing or curettage and grafting can follow frozen section under the same anaesthetic.     

A case of multiple simple bone cysts. With special reference to their etiology and treatment

We report a case of multiple, simple bone cysts in long tubular, short tubular, and flat bones. The internal pressure of the cysts and the oxygen tension of cyst fluid were measured simultaneously. These values were similar to those of typical solitary cysts in other patients. Curettage and bone graft onto the calcaneal cyst were effective, although steroid injection therapy into the metacarpal cyst had no effect. Piercing the ulnar and radial cysts a number of times was uniformly effective. These results may suggest that venous obstruction of the lesions play an important role in the etiology of multiple simple cysts, as shown in typical bone cysts. However, we could not exclude the possibility that simple bone cysts, solitary or multiple, represent some kind of secondary forms of other disorders, or that a simple bone cyst is a heterogeneous entity.     

Selection of procedure in the management of recurrent juvenile and aneurismatic bone cysts

Aneurysmal and juvenile bone cysts are characterized by frequent recurrence and pathological fractures caused by such bone cysts also recur frequently. Curettage of the cyst and spongiosaplasty is often unsuccessful. According to our experience, excochleation must be followed by drilling the cyst wall and fraising off the compact substance. Densely packed homologous spongiosa must then be implanted. In case of recurrence or if the cyst increases in size, radical en-bloc resection is indicated and the defect must be bridged by osteoplastic and osteosynthetic methods. We have treated four difficult cases successfully with this procedure. In one case, resection with limb shortening lead to full recovery.