A comparative study of clinicopathological features between simple bone cysts of the calcaneus and the long bone

Allogenic Cancellous Bone versus Injectable Bone Substitute for Endoscopic Treatment of Simple Bone Cyst and Intraosseous Lipoma of the Calcaneus and Is Intraosseous Lipoma a Developmental Stage of a Simple Bone Cyst?

Simple bone cysts (SBCs) and intraosseous lipoma (IOL) of the calcaneus are rare tumor entities that are primarily diagnosed due to unspecific heel pain, incidental findings, or rarely due to pathological fractures. Compared to traditional open tumor resections, endoscopic resection of these benign tumors aims to minimize surgical morbidity and maximize surgical efficiency without compromising safety. Grafting is regularly performed to reduce the risk of recurrence and stimulate osseous consolidation of the lytic lesion. As the incidence is low and treatment strategies are heterogeneous, there is no clear consensus for the treatment of simple cysts or intraosseous lipomas of the calcaneus. The objectives of this study are (a) to present medium to long-term results after endoscopic resection and grafting with allogenic cancellous bone or bioresorbable hydroxyapatite and calcium sulfate cement, and (b) to add further evidence to the discussion of whether calcaneal SBC and IOL are the same entity at different developmental stages. Between 2012 and 2019, a total of 25 benign bone tumors consisting of 17 SBCs and 8 IOLs were treated by A.T. with endoscopic resection and grafting, comprising the largest cohort to date. For grafting, 12 patients received allogenic cancellous bone (group A) and 13 patients received injectable bone substitute (group B). Pre- and postoperative imaging using plain X-rays and MRI was retrospectively analyzed with a mean follow-up time of 24.5 months to assess tumor size, osseous consolidation (modified Neer classification), and tumor recurrence. A retrospective chart analysis focusing on adverse intra- and perioperative events and other complications associated with the surgical procedure was performed using the modified Clavien-Dindo classification (CD1-3). A total of 12/13 cases with allogenic bone grafting showed a Neer Type 1 osseous healing of the tumorous lesion after endoscopic resection, whereas only 5/11 cases with injectable bone substitute showed sufficient healing (types 1 and 2). There were three recurrent cysts (Neer 4) and two persistent cysts (Neer 3) after using injectable bone substitute. Two CD1 complications were observed in group A (prolonged wound drainage, sural neuritis) and eight complications were observed in group B (6× CD1, 2× CD3). At least two IOLs diagnosed preoperatively using MRI were ultimately identified as SBCs upon histopathologic examination. Allogenic cancellous bone grafting after endoscopic resection of calcaneal SBC or IOL showed a very low rate of complications and no tumor recurrence in our series. On the other hand, depending on the material used, injectable bone substitute showed a high rate of "white-out" (excessive drainage), resulting in multiple complications such as prolonged wound healing, insufficient permanent defect filling, recurrence, and revision surgery. Over time, calcaneal SBC may transform into IOL, exhibiting distinct features of both entities simultaneously during ossoscopy and histopathological analysis.

Open Curettage With Bone Augmentation for Symptomatic Tumors and Tumor-like Lesions of Calcaneus: A Comparison of Bioactive Glass Versus Allogeneic Bone

Few studies have characterized the clinical outcomes of 45S5 Bioglass® applied as a bone graft to that of allogeneic bone applied in calcaneal open curettage. Therefore, the purpose of the present investigation was to compare the outcomes of patients with calcaneal tumors and tumor-like lesions treated by open curettage with 45S5 Bioglass® or allogeneic bone. Of the 31 patients who underwent open curettage (18 cases of unicameral bone cysts, 7 cases of aneurysmal bone cysts, and 6 cases of intraosseous lipoma), 16 (52%) received grafts with 45S5 Bioglass® and 15 (48%) with allogeneic bone. All the feet achieved bone fusion according to the modified Neer radiographic classification system at the last follow-up examination. The mean bone ingrowth time for the grafts with 45S5 Bioglass® versus allogeneic bone was 3.71 ± 0.86 versus 4.46 ± 1.04 months (p = .038), the mean bone healing time was 4.86 ± 0.93 versus 5.73 ± 1.07 months (p = .021), and the mean incision drying time was 7.2 ± 1.8 versus 8.2 ± 1.5 days (p = .047), respectively. No differences were found in the postoperative American Orthopaedic Foot and Ankle Society ankle-hindfoot scale scores between the 2 groups (p = .213). These results show that 45S5 Bioglass® can better facilitate the formation of new bone with a faster drying time of the incision than allogeneic bone. Although both materials can benefit the clinical outcomes of calcaneal tumors and tumor-like lesions, further studies are needed to observe the long-term complications and lesion recurrence rates.

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.

Brodie's abscess of the calcaneus in an adult patient

Brodie's abscess of the calcaneus is an uncommon benign lesion that has rarely been reported in the literature. This study presents a rare case of a Brodie's abscess of the calcaneus caused by Staphylococcus aureus in an adult patient. A 46-year-old immunocompetent man had undergone nonsurgical treatment since childhood owing to the diagnosis of a heel spur. Radiological evaluation revealed a benign radiolucent cystic lesion of the calcaneus surrounded by a sclerotic rim. This condition was accompanied by perilesional bone marrow edema. Thereafter, surgical treatment was planned. During surgery, the content of the lesion was observed to be purulent. Meticulous intralesional debridement was performed, and antibiotic-loaded bone cement beads were placed. Subsequent to microbiological and pathological examinations, the cystic lesion was confirmed to be a Brodie abscess; however, direct clinical evidence of an intraosseous infection was lacking. The patient was followed up for 14 months with no complications until recovery. A Brodie abscess may mimic bone tumors. The onset of a Brodie abscess is insidious, and the clinical findings of such lesions may be obscure. A Brodie abscess of the calcaneus should be considered in the differential diagnosis of patients with chronic heel pain when suspicious radiological findings are evident.

Brodie's abscess of the calcaneus in an adult patient

Brodie's abscess of the calcaneus is an uncommon benign lesion that has rarely been reported in the literature. This study presents a rare case of a Brodie's abscess of the calcaneus caused by Staphylococcus aureus in an adult patient. A 46-year-old immunocompetent man had undergone nonsurgical treatment since childhood owing to the diagnosis of a heel spur. Radiological evaluation revealed a benign radiolucent cystic lesion of the calcaneus surrounded by a sclerotic rim. This condition was accompanied by perilesional bone marrow edema. Thereafter, surgical treatment was planned. During surgery, the content of the lesion was observed to be purulent. Meticulous intralesional debridement was performed, and antibiotic-loaded bone cement beads were placed. Subsequent to microbiological and pathological examinations, the cystic lesion was confirmed to be a Brodie abscess; however, direct clinical evidence of an intraosseous infection was lacking. The patient was followed up for 14 months with no complications until recovery. A Brodie abscess may mimic bone tumors. The onset of a Brodie abscess is insidious, and the clinical findings of such lesions may be obscure. A Brodie abscess of the calcaneus should be considered in the differential diagnosis of patients with chronic heel pain when suspicious radiological findings are evident.

[Foot and ankle tumours : Part I: overview of incidence, diagnosis and staging of pedal tumours]

CLINICAL ISSUE

Foot and ankle tumours are rare. Part I of this paper provides a survey about tumour distribution regarding age and location of benign and malignant bone and soft tissue tumours.

STANDARD RADIOLOGICAL METHODS

All diagnostic radiological procedures are used for the diagnostic work-up of pedal tumours, in particular plain radiography, MRI, and ultrasonography.

METHODICAL INNOVATIONS

Dual-energy CT proves to be a valuable (differential) diagnostic tool in identifying urate dihydrate crystals.

PERFORMANCE

There are no reliable numbers available on accuracy of the aforementioned diagnostic procedures regarding tumour detection and identification. This is particularly true for soft tissue tumours which are small and well-defined, thus requiring histological clarification.

ACHIEVEMENTS

To evaluate pedal tumours correctly and reasonably, a full range of radiological diagnostics should be employed. Neither plain radiography alone nor a stand-alone MRI examination-depending on the tumour site-are sufficient to characterize such tumours including staging.

PRACTICAL RECOMMENDATIONS

Plain radiography remains the first-choice imaging modality. Ultrasonography is superior to reliably detect and identify ganglion cysts. MRI, however, continues to remain the upmost diagnostic modality of choice for evaluating foot and ankle tumours. CT possesses unchallanged diagnostic power to assess osseous changes. Bone scintigraphy (including SPECT-CT) and FDG-PET imaging are used when multifocal distribution or metastatic disease are suspected or to detect avidity of the pedal lesions, respectively.

Primary tumours of the calcaneus

The calcaneus is a rare location for the occurrence and development of primary tumour types. Clinicians are unfamiliar with calcaneal tumour types, which may result in a delay in diagnosis or a missed diagnosis, resulting in unnecessary morbidity and amputation. Heel pain and localized swelling of the ankle are the most common symptoms. X-ray is the first choice for a tentative diagnosis of a calcaneal tumour. The final diagnosis depends on a histological examination. The treatment of calcaneal tumour types varies depending on the Enneking system. The majority of patients with benign tumours heal, except for a few with a palindromia. For malignant tumours, the prognosis is comparatively poor, resulting in disability and a high rate of metastasis. This review describes the spectrum of calcaneal tumour types and specifically illustrates the epidemiology, symptomatology, imagology, histopathology and treatment options that may facilitate diagnosis and improve prognosis.

Treatment outcomes of the simple bone cyst: A comparative study of 2 surgical techniques using artificial bone substitutes

Simple bone cysts (SBCs) are benign lesions of unknown etiology. Because of its high relapse rate, they occasionally need a long period of treatment and restriction of activities in children and adolescent. Although various treatment modalities with variable differing outcomes have been described in the literature, no consensus has been reached regarding the standard treatment. The purpose of this study was to evaluate the outcome of a minimally invasive technique that uses a ceramic hydroxyapatite cannulated pin (HA pin) for the treatment of SBCs.Between 1998 and 2015, we have treated 75 patients with SBCs either with continuous decompression by inserting HA pins after curettage and multiple drilling (group 1, n = 39 patients) or with calcium phosphate cement (CPC) filling after curettage (group 2, n = 36 patients). These patients were retrospectively analyzed for recurrence-free survival (RFS) and factors implicated in SBC recurrence.Seventy-five patients (50 man and 25 females) with a mean age of 17.5 ± 11.6 years and a histopathologically confirmed diagnosis of SBCs were included. The mean follow-up period was 33 ± 25.3 months. RFS were 88% at 1 year and 81% at 5 years. Residual or progressing cysts were observed in 12 patients after the surgery and 10 of them underwent additional surgery. Recurrence rate was significantly higher in patients under the age of 10 years (P = .01), in long bone cysts (P = .01), and in active phase cysts (P = .003) (log-rank test). Multivariate analysis results revealed that age less than 10 years was an independent risk factor of recurrence (P = .04). No significant difference in recurrence rate was observed between groups 1 and 2. However, the mean operating time was significantly shorter in group 1. (62.4 ± 25.6 vs 110.5 ± 48.4 minutes in group 2).Continuous decompression using HA pin is a less invasive surgical technique for the treatment of SBCs compared with CPC filling and has a high healing rate. The relapse rate was still high when the cysts were caused in children aged less than 10 years, located in the long bone, or remained adjacent to the epiphysis.

LEVEL OF EVIDENCE

Level 3, Retrospective comparative study.

Calcaneal cysts and lipomas: a common pathogenesis?

Calcaneal cysts and lipomas are relatively rare, benign bone lesions. They are similar in many ways, including in their location and radiological appearance, but their content differs. Cysts contain fluid whereas lipomas contain fat, although some lesions may exhibit a mixed content. The pathogenesis of the two entities is the subject of controversy. The theory that calcaneal cysts may result from lipomatous necrosis has been widely suggested in the literature, but no such progression has ever been shown. The contrary hypothesis has also been considered, i.e., that the content of regressing cysts may be replaced by fatty marrow, leading to a lipoma-like appearance. This second theory is based on indirect arguments, notably that lipomas have a similar location to intraosseous calcaneal ganglion cysts that arise from the subtalar joint and that patients are older in cases of calcaneus lipomas than in cases of calcaneus cysts. We offer an additional argument in favor of this hypothesis. We present an original observation of a calcaneal cyst incidentally discovered in a 15-year-old male whose spontaneous evolution 3 and 7 years later revealed progressive replacement of its fluid content by fat.

Unicameral Bone Cyst of the Medial Cuneiform

A unicameral bone cyst is a relatively uncommon, benign bone tumor found in the metaphysis of long bones, such as the humerus and the femur, in skeletally immature persons. In the foot, these benign, fluid-filled cavities are most commonly found within the os calcis. We present a case report of a 10-year-old female with a unicameral bone cyst of the medial cuneiform.

Calcaneal Ossoscopy

Both unicameral bone cysts and intraosseous lipoma of the calcaneus are rare entities that are mostly diagnosed because of unspecific heel pain, pathologic fracture, or as incidental finding. Minimally invasive ossoscopy with endoscopic resection of the tumor followed by grafting can potentially minimize risks of open surgery and speed up convalescence. We present our modifications to previously described techniques of endoscopic curettage with a particular focus on intraosseous lipoma and allogenic grafting. The key point for grafting is the use of a funnel-shaped ear speculum facilitating the plombage with allogenic cancellous bone chips. Compared with its alternatives, grafting with allogenic cancellous bone might prove favorable in this localization for several reasons: osteointegration, handling, availability, and costs. The objective of this technical note is to present a simple, safe, and cost-effective surgical technique for endoscopic surgical treatment of benign osteolytic lesions of the calcaneus.

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.