Joint contractures can be due to a variety of conditions. These include inherited disease (syndromes such as arthrogryposis with contractures present from birth) through to conditions where contractures develop with time (such as genetic conditions including some forms of mucopolysaccharidoses [MPS], skeletal dysplasias or inherited myopathies such as Duchenne Muscular Dystrophy) or cerebral palsy (with changes being symmetrical or more commonly asymmetrical with other features of increased tone). There may be other features such as abnormality of growth (short stature or short limbs), bone deformity or malalignment (eg bow legs), developmental delay or a significant family history.
Inflammatory disease can also result in joint contractures - these include Juvenile Idiopathic Arthritis, Juvenile Dermatomyositis (JDM) and some forms of Scleroderma (morphoea).
Careful clinical assessment (history and examination including birth history, family history) are important.
The pattern of joint contracture is important in the differential diagnosis and pGALS is helpful to identify the extent and pattern of joint involvement, such as in some forms of MPS.
The images below demonstrate contractures at the shoulders, fingers, wrists, knees, hips and increased lumbar lordosis - this patient has Hurler-Scheie form of MPS 1 (a form of MPS that can be indolent and progressive - treatment is available [enzyme replacement therapy] so if suspected, specialist referral is required depending on local availability and referral pathways (e.g metabolic medicine, / paediatric neurology or neurodisability / paediatric rheumatology)
A video demonstration of joint examination in this young boy is available. The demonstration uses pGALS and pREMS to assess his joints.
The algorithm below is helpful to consider MPS in the context of multisystem problems and to differentiate between the causes of joint contractures and when to suspect MPS.
Investigations in the context of joint contractures will be determined by the clinical assessment and suspected diagnoses. It is important to consider specialist referral as often a diagnosis is determined by a combination of investigations. Tests may include:
- Blood tests including full (complete) blood count, inflammatory markers (ESR, CRP)
- Muscle enzymes for muscle disease (inflammatory or inherited)
- Urine for glycosaminoglycans (GAGs) to help exclude MPS (Urine GAGS can be normal in MPS so if concerned, further specialist advice is needed)
- Imaging of joints, bone skeleton or muscle (such as ultrasound or MRI)
- Biopsy of skin, joint or muscle
- Genetic tests (for muscle tests or MPS disorders or other syndromes)
- Thermography and capillaroscopy (investigation for morphoea or JDM)