Hypermobility in Children
Hypermobility is a common condition in children, characterised by an excessive range of motion in their joints. While it’s often a benign and normal variant of musculoskeletal development, it can also be a sign of an underlying connective tissue disorder, which requires a careful clinical assessment to differentiate.
Aetiology and Differential Diagnoses
Benign Hypermobility: The most common cause, this is a normal developmental variation that often improves with age. It’s diagnosed when hypermobility is the only finding and there are no associated symptoms or underlying conditions.
Ehlers-Danlos Syndrome (EDS): A group of inherited connective tissue disorders. Hypermobility is a key feature, along with skin hyperextensibility, tissue fragility, and other systemic issues.
Marfan Syndrome: An autosomal dominant connective tissue disorder. Hypermobility is common, along with other features such as tall stature, arachnodactyly (long, slender fingers), and, most importantly, cardiovascular abnormalities like aortic dilation.
Other conditions: Hypermobility can also be a feature of a number of other conditions, including osteogenesis imperfecta, Down’s syndrome, and rheumatological conditions like juvenile idiopathic arthritis.
Clinical Assessment
Red Flags
The presence of any of these red flags should prompt a more thorough investigation and specialist referral:
Cardiovascular: A new or existing heart murmur, or a family history of sudden death.
Neurological: Muscle weakness, hypotonia, abnormal neurology, or ataxia.
Musculoskeletal: Scoliosis, recurrent joint dislocations, or a history of easy bruising.
Dysmorphism: Any notable dysmorphic features.
History
A thorough history is crucial. Ask about the joints involved, the onset and duration of symptoms, and what triggers or relieves the pain. Enquire about systemic symptoms such as easy bruising or dizzy spells, which can be signs of a connective tissue disorder.
Examination
General: Plot the child’s height, weight, and head circumference on a growth chart. Check for marfanoid features, such as a tall, thin body habitus and an increased arm span-to-height ratio.
Joints: Perform a full joint examination, assessing for any signs of swelling, warmth, or redness.
Beighton Hypermobility Score: This is the most common tool used to quantify hypermobility. A score of 4 or more is considered positive.
Brighton Diagnostic Criteria: The Brighton criteria are a more formal diagnostic tool for Joint Hypermobility Syndrome and include both the Beighton score and a number of other systemic features.
Investigations and Management
Investigations: For benign hypermobility, no investigations are generally required. If an underlying condition is suspected, investigations may include blood tests for inflammatory markers or autoimmune antibodies, a genetic opinion, or a cardiac workup with an ECG and echocardiogram.
Management:
Education and Reassurance: For benign hypermobility, the key is to reassure the family that it is not a disease and will likely improve.
Physiotherapy: This is the cornerstone of management. A physiotherapist can teach the child strengthening exercises to improve joint stability.
Pain Management: Analgesics do not usually help with hypermobility-related pain. Rest, distraction, and massage can be helpful.