What is the "musculoskeletal system"?

Muscles and bones in children comprise a dynamic system that physicians call the "musculoskeletal system".  Unlike adults, children's muscles and bones are growing significantly, and so these important body parts have needs that are distinct from those in adults.  For example, children must have a recurring source of calcium and vitamin D to support rapid bone growth, or they will suffer from a formerly common disease, rickets.  On the other hand, this rapid growth provides a greater degree of "reparability" when children damage their bones, unlike adults.  Thus, children's musculoskeletal health is handled differently from that in adults by specialists such as pediatric orthopedists, pediatric rheumatologists, and general pediatricians.

What are musculoskeletal diseases?

The range of muscle and bone diseases in children is immense.  A partial list of categories of disorders and some examples includes:

·         Genetic = familial conditions caused by recognized genetic defects, such as dwarfism (achondroplasia), clubfoot, rheumatoid arthritis, and metabolic disorders like rickets and the bone and muscle manifestations of hypothyroidism

·         Tumors = cancerous and non-cancerous lesions of the bones and muscles, such as bone cysts, osteosarcoma, and infantile myofibromatosis

·         Developmental = conditions related to problems with development of the bones and muscles, like scoliosis and Legg-Calvé-Perthes Disease

·         Trauma = among the most common causes of musculoskeletal problems, these disorders range from overuse injuries like Little Leaguer's Elbow to severe trauma such as after an automobile accident

·         Infections = diseases that occur when a particular bacteria, fungus, or virus causes an infection that affects the bones or muscles, like osteomyelitis or the bone and muscle effects of a polio infection of the spine

·         Neuromuscular = diseases involving the brain, spinal cord, and/or nerves may also result in childhood disability. Examples include cerebral palsy, spina bifida, and the muscular dystrophies

The spectrum of bone and muscle disorders in childhood spans many different fields, necessitating complex management scenarios that often involve a number of health care providers and substantial cost.  The diagnosis of these disorders involves many different types of health care professionals and diagnostic modalities, like x-rays, computed tomography (CT) scans, magnetic resonance imaging (MRI) scans, blood tests for genetic disorders, and sophisticated motion lab analyses.  Specialists in medicine, surgery, physical medicine and rehabilitation, physical therapy, occupational therapy, and prosthetic manufacturing all provide care for these children, often in carefully coordinated teams that optimize a child's health care experience.

Burden of care

Pediatric muscle and bone diseases exact a substantial cost on society, as well as the families of these children.  Children with these disorders often have chronic courses that require complicated therapies and specific medical equipment like wheelchairs, walkers, prostheses, and implanted surgical devices that can cost many thousands of dollars.  Additionally, children with musculoskeletal diseases may need complex and expensive medical treatments, such as the use of alendronate for children with osteogenesis imperfecta. 

Courses of therapy may be required for many years, but the results are often spectacular.  For example, the increasing use of casting techniques to correct clubfeet in children has led to improved correction of the deformity of an affected foot with less pain for the afflicted child and lower cost of care. As the underlying genetic causes of these disorders are identified, specific gene therapies will become more commonplace and reduce the burden of care, as well as the long term costs of care.  The need for research in this area has never been greater, as the knowledge base regarding the fundamental causes of these conditions is expanding rapidly, leading to newer and better treatments.

The cost of childhood musculoskeletal diseases is high, both in human terms and in direct and indirect costs to society.  Investment in research into these disorders has paid off in the past with new treatments, such as the Ponseti technique for treating clubfeet, and the expanding areas of genomics and medical treatments of diseases that were once considered incurable have made this area of health care particularly intriguing and satisfying.  Future progress depends on the resolve and dedication of health care professionals and political leaders, as well as the will of society to find ways of easing the burden of these diseases on our most vulnerable population - our children.

Research programs

Since these conditions comprise such a broad scope of diseases, research is being conducted on many fronts.  Research efforts not only focus on new/evolving strategies for diagnosis and treatment, but also on ways to decrease the burden of musculoskeletal diseases through prevention.  Research falls into three categories:

1.      Biomedical research = sometimes called basic or "bench" research, this approach focuses on the underlying causes of bone and joint disease in children, along with potential therapies directed at the underlying causes, rather than the symptoms.  Probing cellular mechanisms of disease, these therapies show great promise and include genetic conditions like osteogenesis imperfecta and other diseases like bone cancer.  By understanding the mechanisms of diseases and then redirecting the body's resources to enhance weak or disordered functions, our ability to treat debilitating musculoskeletal conditions will be greatly improved.  Some of these research efforts include the fields of genomics and proteomics, which show great promise in helping doctors understand diseases in ways that make treatments more specific to the clinical condition and the person with the affliction.  These promising therapies provide the possibility of a cure, rather than just treating symptoms, with a reduced probability of causing harm from the treatment.

2.      Translational research = taking the information gained from biomedical research and showing how it can be applied in real world situations is the task of translational research.  Currently a focus of the Agency for Healthcare Quality and Research (AHRQ), this area of scientific inquiry seeks to reduce the time between new discoveries and their application in clinical practice. Since this is such a new area and of critical importance to the health care industry, far more funding will be needed to successfully achieve the goal of bringing advanced care to the population.

3.      Clinical research = building on the foundations of biomedical and translational research, clinical research takes the knowledge gained from the other disciplines to large groups of people with a clinical condition.  Clinical researchers are usually skilled clinicians (physicians) who can also take the rigorous scientific approach required for effective analysis of the effects of a treatment across large groups of people.  Clinical research is truly "where the rubber hits the road", but these expensive research projects require substantial funding to succeed.  Without this third important component, though, new discoveries that can ease the suffering and burden of disease.

Future directions for research

The Human Genome Project (which determined the sequence of all the different genes in human DNA) produced a startling amount of information in a relatively short time, but we're only beginning to tap that resource to find innovations in medical and surgical treatments.  The health care provider of the future will have a whole new armamentarium available to tailor treatments based not just on an individual's diagnosis, but also on myriad other factors such as the genetic profiles of the individual and the aberrant systems in the body causing the disease.  New diagnostic modalities will be able to identify children at risk for certain hereditary diseases and allow their physicians to intervene early to prevent major damage from the disease.  These early diagnosis and intervention strategies are being devised in the laboratories and clinical studies today, but they require continued, sustained funding to ensure that scientists and clinicians can continue to make progress in this never-ending struggle.

Useful resources

American Academy of Pediatrics - www.aap.org  

Pediatric Orthopaedic Society of North America - www.posna.org

Shriners Hospitals for Children - www.shrinenet.org

Condition Kit on Musculoskeletal Diseases in Children

Produced by the

United States Bones and Joint Decade, NFP

July 2005

7/20/05