Skeletal Health Center

Skeletal dysplasias are a group of disorders characterized by abnormalities in the growth and development of bone and cartilage. These conditions typically result in disproportionate short stature, where different parts of the body may grow at varying rates or in abnormal patterns. Skeletal dysplasias encompass a wide range of disorders and often have genetic origins. Each affects the skeletal system in different ways.

Common features of skeletal dysplasias can include:

• Short stature: Individuals may have a significant reduction in height compared to average expectations for age and sex.
• Bone malformations: These can include curvatures, abnormal shapes, or other irregularities in the bones.
• Joint issues: There may be limitations in joint mobility or development of osteoarthritis at an early age.
• Facial and cranial differences: Features such as a prominent forehead or specific cranial shapes may be present.

There are more than 350 types of skeletal dysplasias. Common dysplasias include:

• Osteogenesis imperfecta: Also known as brittle bone disease, this is a rare condition in which genetic mutations in collagen lead to fragile and easily fractured bones.
• Achondroplasia: The most common form of dwarfism, achondroplasia is caused by mutations affecting bone growth and resulting in short stature, especially in the limbs.
• Type II collagenopathies: This is a group of disorders that affect type II collagen (such as spondyloepiphyseal dysplasia congenita), leading to short stature and spinal and eye abnormalities.
• Thanatophoric dysplasia: This severe skeletal disorder often results in the baby not surviving long after birth and is characterized by extremely short limbs and a narrow thorax.
• Diastrophic dysplasia: This condition is characterized by limb shortening, joint contractures, and distinctive ear abnormalities, often with normal-sized trunk stature.
• Metatopic dysplasia: This rare condition is marked by craniosynostosis, midface hypoplasia, and shortening of the limbs and trunk.
• Metaphyseal dysplasia: This features abnormalities in the metaphysis of bones, leading to short stature and limb deformities.
• Cartilage-hair hypoplasia: This condition is characterized by short stature, fine sparse hair, and immune system deficiencies.
• Acromesomelic dysplasias: This group of disorders involves shortening of the middle and distal segments of the arms and legs.
• Campomelic dysplasia: This severe condition involves bowing of the long bones and distinct facial features, often with other systemic abnormalities.
• Pseudoachondroplasia: This condition is similar in appearance to achondroplasia but with normal head size and distinct joint problems and disproportionate short limbs.

Management of skeletal dysplasias involves a multidisciplinary approach that focuses on addressing symptoms, improving quality of life, and providing supportive care where necessary. We develop personalized treatment plans to address each child’s unique needs, incorporating surgical interventions and therapies to improve mobility and daily functioning. The Skeletal Health Center ensures coordinated care through seamless communication between providers, while also offering family education, long-term monitoring, and psychosocial support to enhance the quality of life. Research initiatives within the center continually advance understanding and treatment options to improve patient outcomes.

These are a group of disorders caused by genetic mutations affecting the development, structure, and function of bones. These conditions result from alterations in the DNA sequence, which can impact various aspects of bone growth, mineralization, and maintenance. Genetic bone diseases can manifest in different ways, ranging from abnormalities in bone shape and size to issues with bone density, strength, and overall skeletal integrity. Many types of skeletal dysplasias have a genetic component.

Other genetic bone diseases include:

• Fibrous dysplasia: This disorder involves abnormal growth of fibrous tissue in place of normal bone, leading to weak and misshapen bones.
• Multiple hereditary exostoses: A condition characterized by the growth of multiple benign bone tumors (exostoses) on the surface of bones, leading to skeletal deformities and potential functional limitations.
• Osteopetrosis: Also known as marble bone disease, this condition is caused by impaired resorption, leading to excessive bone density and increased susceptibility to fractures.

Genetic bone diseases can be caused by mutations in specific genes that play crucial roles in bone formation, growth, and maintenance. The severity and clinical features of these conditions can vary widely, and they often require specialized medical management, including symptom relief, fracture prevention, and supportive care. In some cases, ongoing research and advances in genetics may lead to improved understanding and treatment options for genetic bone diseases.

These are disorders that impact the structure and strength of bones due to abnormalities in mineralization of the skeleton. Metabolic bone diseases often involve disturbances in the balance of minerals in the bones and blood, like calcium, phosphorus, and magnesium. The diseases can lead to weakened bones, increased susceptibility to fractures, poor growth, and other skeletal problems.

During childhood, the skeleton grows and becomes stronger only if there is sufficient intake of calcium through the diet and vitamin D (a hormone that helps the intestine absorb calcium) through foods, vitamins, and sunlight. With a calcium-rich diet, cells in the bone add calcium, phosphorus, and magnesium to the skeleton in response to hormonal signals from the body. Metabolic bone disease can result from low vitamin D, low calcium, or problems with the hormonal signals to the bones.

An evaluation of metabolic bone disease involves measuring the minerals and hormones in blood and urine, imaging of the skeleton, a full dietary evaluation, and in some cases, genetic testing. Imaging of the skeleton can involve X-rays to investigate the shape of the skeleton and look for fractures. We also conduct bone density testing through dual-energy X-ray absorptiometry (DXA). DXA is a specialized low-radiation test that measures the amount of mineral in the bones to understand a child’s fracture risk.

Metabolic bone diseases include:

• Hypoparathyroidism: A disorder characterized by abnormally low levels of parathyroid hormone (PTH), leading to low blood calcium levels and potentially causing muscle cramps, weakness, and other symptoms.
• Hypophosphatasia: A genetic disorder characterized by low levels of an enzyme called alkaline phosphatase, leading to impaired bone mineralization and weak bones. It can be treated with alkaline phosphatase enzyme replacement, a medication called asfotase alfa.
• Hypophosphatemia: A condition marked by abnormally low levels of phosphate in the blood. Depending on the cause, it can be treated with a new medication, burosumab, that targets the FGF-23 hormone.
• Hypovitaminosis D: A condition characterized by insufficient levels of vitamin D in the body, which can lead to weakened bones and other health issues.
• Hyperparathyroidism: A condition where the parathyroid glands produce excessive parathyroid hormone (PTH), potentially leading to elevated blood calcium levels.
• Osteomalacia: A disorder in which bones become weak and soft due to inadequate mineralization, often caused by vitamin D deficiency.
• Pseudohypoparathyroidism: A rare genetic disorder that mimics the symptoms of hypoparathyroidism, where the body does not respond appropriately to PTH.
• Rickets: A childhood disorder characterized by weak and deformed bones, often caused by vitamin D, calcium, or phosphate deficiency.

Chronic illness in children can adversely impact bone health, growth, and development. A prolonged inflammatory state, altered hormonal balance, and potential side effects of medications can impede the body's ability to build and maintain strong bones. As a result, children with chronic illnesses may experience reduced bone density, increased susceptibility to fractures, and compromised growth potential.

Multidisciplinary care — including close collaboration between pediatricians, endocrinologists, surgeons, and specialists in chronic conditions — is crucial to monitor and address skeletal health in these young patients. Early intervention strategies, such as nutritional optimization, physical therapy, and targeted medications, aim to mitigate the impact of chronic illness on skeletal fragility and provide children with the best possible foundation for a healthy and active life.

We work closely with specialists from across Boston Children’s Hospital because low bone density may be related to secondary medical conditions such as:

• Inflammatory bowel disease
• Parenteral nutrition
• Muscular dystrophy
• Long-term steroid use
• Cerebral palsy
• Cystic fibrosis
• Spina bifida

Optimal bone health is paramount for student athletes. Good bone health can enhance performance and reduce the risk of injuries, and it lays the foundation for lifelong skeletal well-being.

Recognizing the crucial role of bone health in both performance and long-term well-being, our initiatives provide tailored solutions for female athletes and all young sports enthusiasts. Boston Children’s Female Athlete Program is dedicated to empowering young female athletes, focusing on optimizing bone health to unlock their true capabilities while safeguarding against injuries. Similarly, the staff of our Sports Medicine Division extend their expertise to all young athletes, fostering peak performance and resilience through evidence-based practices.