Osteopetrosis: radiological & radionuclide imaging

Spontaneous Anterior Arch Fracture of the Atlas Following C1 Laminectomy in a Patient With Osteopetrosis: A Case With Five Years of Follow-Up

Osteopetrosis is a rare group of genetic disorders characterized by excessive bone density due to impaired osteoclast function and can lead to various complications, including fractures and immune dysfunction. We describe the case of a 63-year-old man with osteopetrosis who presented with cervical discomfort and was diagnosed with an anterior arch fracture of the atlas, a rare spontaneous fracture following C1 laminectomy. Initially, no neurological abnormalities were observed, and imaging confirmed the continuity of the transverse ligament. Thus, the decision was made to follow the natural course in the absence of instability. Conservative treatment with a cervical collar was initiated, and the fracture gap began to fill by three years postoperatively, though nonunion persisted at five years. The patient remained asymptomatic and did not require further surgical intervention. This case highlights that stress concentrated on the anterior arch of the atlas due to the unique bone quality in osteopetrosis, and the subsequent natural course of the fracture did not require additional surgical treatment. Careful follow-up is essential to monitor for any pathological changes.

Multiple oral sinus tract and trismus leading to a surprising diagnosis of osteopetrosis: Case report

AIMS

We report a rare case of late diagnosis of malignant osteopetrosis in a 36-year-old male patient due to multiple intraoral sinus tracts and trismus.

CASE REPORT

The patient reported a history of facial scars that could not be attributed to the older external fistulas that were present and various complicated dental extractions since infancy. In addition, the patient had not been previously diagnosed with any other significant diseases other than blindness since infancy. Computed tomography revealed a marble-like sclerotic pattern of all cranial bones, a thickened parietal bone, and a narrowing of the encephalic space and the optic canal. Further laboratory and imaging studies revealed complete sclerosed bone of the chest and pelvis, anemia, reticulocitosis, extramedular hematopoiesis, altered dehydrogenasis lactate, and acid phosphatasis. An interdisciplinary treatment was initiated with medical and dental care monitoring. The patient is still receiving attention after 4 years of follow-up.

CONCLUSIONS

The outcome of this case represents the daily challenges faced by interdisciplinary care providers and reveals pearls and pitfalls that can serve as a reference for professional practice in such cases.

Spectrum of Skeletal Imaging Features in Osteopetrosis: Inheritance Pattern and Radiological Associations

Osteopetrosis (from the Greek "osteo": bone; "petrosis": stone) is a clinically and genetically heterogeneous group of rare diseases of the skeleton, sharing the same main characteristic of an abnormally increased bone density. Dense bones in radiological studies are considered the hallmark of these diseases, and the reason for the common term used: "Marble bone disease". Interestingly, a radiologist, Dr. Albers-Schonberg, described this disease for the first time in Germany in 1904. Indeed, radiology has a key role in the clinical diagnosis of osteopetrosis and is fundamental in assessing the disease severity and complications, as well as in follow-up controls and the evaluation of the response to treatment. Osteopetrosis includes a broad spectrum of genetic mutations with very different clinical symptoms, age onset, and prognosis (from mild to severe). This diversity translates into different imaging patterns related to specific mutations, and different disease severity. The main recognized types of osteopetrosis are the infantile malignant forms with autosomal recessive transmission (ARO-including the rarer X-linked recessive form); the intermediate autosomal recessive form (IAO); and the autosomal dominant ones ADO, type I, and type II, the latter being called 'Albers-Schonberg' disease. Imaging features may change among those distinct types with different patterns, severities, skeletal segment involvement, and speeds of progression. There are several classical and well-recognized radiological features related to osteopetrosis: increased bone density (all types with different degrees of severity assuming a 'Marble Bone Appearance' especially in the ARO type), different metaphyseal alterations/enlargement including the so-called 'Erlenmeyer flask deformity' (particularly of femoral bones, more frequent in ADO type 2, and less frequent in ARO and IAO), 'bone in bone' appearance (more frequent in ADO type 2, less frequent in ARO and IAO), and 'rugger-jersey spine' appearance (typical of ADO type 2). After conducting an overview of the epidemiological and clinical characteristic of the disease, this review article aims at summarizing the main radiological features found in different forms of osteopetrosis together with their inheritance pattern.

Progressive skeletal defects caused by Kindlin3 deficiency, a model of autosomal recessive osteopetrosis in humans

The cellular and molecular mechanisms of bone development and homeostasis are clinically important, but not fully understood. Mutations in integrins and Kindlin3 in humans known as Leukocyte adhesion deficiencies (LAD) cause a wide spectrum of complications, including osteopetrosis. Yet, the rarity, frequent misdiagnosis, and lethality of LAD preclude mechanistic analysis of skeletal abnormalities in these patients. Here, using inducible and constitutive tissue-specific Kindlin3 knockout (K3KO) mice, we show that the constitutive lack of embryonic-Kindlin3 in myeloid lineage cells causes growth retardation, edentulism, and skull deformity indicative of hydrocephaly. Micro-CT analysis revealed craniosynostosis, choanal stenosis, and micrognathia along with other skeletal abnormalities characteristic of osteopetrosis. A marked progression of osteosclerosis occurs in mature to middle-aged adults, resulting in the narrowing of cranial nerve foramina and bone marrow cavities of long bones. However, postnatal-Kindlin3 is less critical for bone remodeling and architecture. Thus, myeloid Kindlin3 is essential for skeletal development and its deficiency leads to autosomal recessive osteopetrosis (ARO). The study will aid in the diagnosis, management, and treatment choices for patients with LAD-III and ARO.

An Extremely Rare, Atypical and Genetically-undetermined Form of Osteopetrosis

INTRODUCTION

Osteopetrosis is an uncommon skeletal disorder characterized by generalized sclerosis of bones due to defective osteoclast function. A wide variation in clinical severity of the disease has been observed. Radiographic features and genetic testing are commonly used to diagnose the condition.

CASE PRESENTATION

In the present study, we present a case of an extremely rare, atypical and genetically- undetermined form of Osteopetrosis.

CONCLUSION

This patient had some clinical and radiological features of craniometaphyseal dysplasia along with atypical radiological signs of osteopetrosis.

Pelvic radiograph in skeletal dysplasias: An approach

The bony pelvis is constituted by the ilium, ischium, pubis, and sacrum. The pelvic radiograph is an important component of the skeletal survey performed in suspected skeletal dysplasia. Most of the common skeletal dysplasias have either minor or major radiological abnormalities; hence, knowledge of the normal radiological appearance of bony pelvis is vital for recognizing the early signs of various skeletal dysplasias. This article discusses many common and some uncommon radiological findings on pelvic radiographs along with the specific dysplasia in which they are seen; common differential diagnostic considerations are also discussed.

Radiographic imaging, densitometry and disease severity in Autosomal dominant osteopetrosis type 2

OBJECTIVE

To characterize relationships between quantitative computed tomography bone mineral density measurements and other qualitative and quantitative imaging measures, as well as clinical metrics, in patients with autosomal dominant osteopetrosis type 2 (ADO2).

MATERIALS AND METHODS

Clinical and radiologic parameters of 9 adults and 3 children with autosomal dominant osteopetrosis type 2 were assessed including lumbar spine quantitative computed tomography (QCT), radiographic skeletal survey (skull base thickening; Erlenmeyer flask deformity; endobone pattern; and spine density pattern (endplate sclerosis, "anvil" appearance, or diffuse sclerosis)), dual-energy x-ray absorptiometry (DXA), tibial peripheral quantitative computed tomography (pQCT) volumetric bone mineral density (vBMD), bone turnover markers, and bone marrow failure or visual impairment.

RESULTS

The skeletal parameter most divergent from normal was lumbar spine QCT Z-score (+ 3.6 to + 38.7). Lumbar QCT Z-score correlated positively with pQCT tibial diaphysis vBMD (Pearson correlation r = 0.73, p = 0.02) and pQCT tibial metaphysis vBMD (r = 0.87, p < 0.01). A trend towards positive lumbar QCT Z-score correlation with serum P1NP/CTX ratio (r = 0.54, p = 0.10) and lumbar DXA Z-score (r = 0.55, p = 0.10) were observed. Bone marrow failure and vision impairment occurred in those with most severe quantitative and qualitative measures, while those with less severe radiographic features had the lowest QCT Z-scores.

CONCLUSION

Lumbar spine QCT provided the most extreme skeletal assessment in ADO2, which correlated positively with other radiologic and clinical markers of disease severity. Given the quantification of trabecular bone and greater variation from normal with wider range of values, lumbar QCT Z-scores may be useful to determine or detect impact of future treatments.

Diagnosis and management of pediatric metabolic bone diseases associated with skeletal fragility

PURPOSE OF REVIEW

The goal of this review is to give an overview of diagnosis and up-to-date management of major pediatric metabolic bone diseases that are associated with bone fragility, including nutritional rickets, hypophosphatemic rickets, osteogenesis imperfecta, Ehlers--Danlos syndrome, Marfan's syndrome, hypophosphatasia, osteopetrosis and skeletal fluorosis.

RECENT FINDINGS

During the past decade, a number of advanced treatment options have been introduced and shown to be an effective treatment in many metabolic bone disorders, such as burosumab for hypophosphatemic rickets and asfotase alfa for hypophosphatasia. On the other hand, other disorders, such as nutritional rickets and skeletal fluorosis continue to be underrecognized in many regions of the world. Genetic disorders of collagen-elastin, such as osteogenesis imperfecta, Ehlers--Danlos syndrome and Marfan's syndrome are also associated with skeletal fragility, which can be misdiagnosed as caused by non-accidental trauma/child abuse.

SUMMARY

It is essential to provide early and accurate diagnosis and treatment for pediatric patients with metabolic bone disorders in order to maintain growth and development as well as prevent fractures and metabolic complications.

Bone Scintigraphy: A Review of Technical Aspects and Applications in Orthopedic Surgery

Due to its high sensitivity, low cost, accessibility, and ease of use, bone scintigraphy is used in orthopedic surgery for the diagnosis and management of varied pathology. It is commonly used for insufficiency fractures, metastatic neoplasia, staging and surveillance of sarcoma, and nonaccidental trauma. It augments diagnoses, including stress or occult fractures, musculoskeletal neoplasia or infection, and chronic regional pain syndrome, in patients presenting with normal results on radiographs. Bone scan images are resistant to metal-based implant artifact, allowing effective evaluation of failed total joint prostheses. Bone scintigraphy remains an underused tool in the evaluation and management of orthopedic patients. [Orthopedics. 2019; 42(1):e14-e24.].

Cervical spine fractures in osteopetrosis: a case report and review of the literature

While management of appendicular fractures has been well described in the setting of osteopetrosis, there is limited information on managing fractures of the axial spine. Here we present an osteopetrotic patient with multiple traumatic multiple, comminuted, unstable cervical spinal fractures managed with non-operative stabilization, and provide a review of the pathophysiology, genetic characteristics, and special considerations that must be explored when determining operative versus non-operative management of spinal injury in osteopetrosis. A PubMed query was performed for English articles in the literature published up to June 2016, and used the following search terms alone and in combination: "osteopetrosis", "spine", "fractures", "osteoclasts", and "operative management". Within four months after initial injury, treatment with halo vest allowed for adequate healing. The patient was asymptomatic with cervical spine dynamic radiographs confirming stability at four months. On four-year follow up examination, the patient remained without neck pain, and CT scan demonstrated partially sclerotic fracture lines with appropriate anatomical alignment. In conclusion, external halo stabilization may be an effective option for treatment of multiple unstable acute traumatic cervical spine fractures in patients with osteopetrosis. Given the challenge of surgical stabilization in osteopetrosis, further research is necessary to elucidate the optimal form of treatment in this select patient population.

Decompressive Cranioplasty in a Patient with Osteopetrosis

BACKGROUND

Osteopetrosis is a heterogeneous group of uncommon congenital disorders that causes bony sclerosis and remodeling. Patients who are symptomatic can show significant neurologic consequences with the involvement of cranial nerves and symptoms of increased intracranial pressure (ICP).

CASE DESCRIPTION

We report an unusual case of a 26-year-old woman with an autosomal-dominant type of osteopetrosis who presented with headache and severe visual deterioration, both attributed to increased ICP. A hemicranioplasty was preformed, resulting in the resolution of her symptoms of ICP and stabilization of her vision. Postoperative imaging showed expansion of the ventricles and the subarachnoid spaces with an improvement of the associated cerebellar herniation.

CONCLUSIONS

In conclusion, in patients with symptomatic osteopetrosis, cranioplasty can be considered as an option to treat high ICP-related symptoms.

Autosomal recessive osteopetrosis with a unique imaging finding: multiple encephaloceles

Osteopetrosis is a hereditary form of sclerosing bone dysplasia with various radiological and clinical presentations. The autosomal recessive type, also known as malignant osteopetrosis, is the most severe type, with the early onset of manifestations. A 5-month-old infant was admitted to our hospital with recurrent respiratory tract infections. Chest X-ray and skeletal survey revealed the classic findings of osteopetrosis, including diffuse osteosclerosis and bone within a bone appearance. At follow-up, the patient presented with, thickened calvarium, multiple prominent encephaloceles, and dural calcifications leading to the intracranial clinical manifestations with bilateral hearing and sight loss. Autosomal recessive osteopetrosis is one of the causes of encephaloceles and this finding may become dramatic if untreated.

Sclerosing bone dysplasias: genetic, clinical and radiology update of hereditary and non-hereditary disorders

There is a wide variety of hereditary and non-hereditary bone dysplasias, many with unique radiographic findings. Hereditary bony dysplasias include osteopoikilosis, osteopathia striata, osteopetrosis, progressive diaphyseal dysplasia, hereditary multiple diaphyseal sclerosis and pyknodysostosis. Non-hereditary dysplasias include melorheostosis, intramedullary osteosclerosis and overlap syndromes. Although many of these dysplasias are uncommon, radiologists should be familiar with their genetic, clinical and imaging findings to allow for differentiation from acquired causes of bony sclerosis. We present an overview of hereditary and non-hereditary bony dysplasias with focus on the pathogenesis, clinical and radiographic findings of each disorder.

A case of infantile osteopetrosis: The radioclinical features with literature update

BACKGROUND

Osteopetrosis is a rare hereditary metabolic bone disorder characterized by generalized skeletal sclerosis caused by a defect in bone resorption and remodelling. Infantile autosomal recessive osteopetrosis is one of three subtypes of osteopetrosis and the most severe form. The correct and early diagnosis of infantile osteopetrosis is important for management of complications and for future genetic counselling. Diagnosis is largely based on clinical and radiographic evaluation, confirmed by gene testing where applicable.

METHODS

Therefore, in this case study the classical clinical and radiological signs of a boy with infantile osteopetrosis will be presented with a comprehensive literature update. The differentiating signs from other causes of hereditary osteosclerosing dysplasias are discussed.

RESULTS

This case study and review of available literature show that there tends to be a highly unique clinical and skeletal radiographic pattern of affection in infantile osteopetrosis.

CONCLUSION

Although tremendous advances have been made in the elucidation of the genetic defect of osteopetrosis over the past years, the role of accurate clinical and radiological assessment remains an important contributor to the diagnosis of infantile osteopetrosis.