Arthrogryposis Multiplex Congenita
On this page
Direct answer
Arthrogryposis multiplex congenita is a descriptive term for multiple joint contractures present at birth, with stiff, fixed joints that reflect reduced fetal movement. Amyoplasia is its commonest form, in which muscle is replaced by fibrous and fatty tissue while intelligence is usually normal. Management follows a clear sequence: early passive stretching and serial casting to correct the contractures, then surgery to restore function.
What you must remember
- Definition: a clinical description, not one disease, of multiple non-progressive joint contractures present at birth.
- Amyoplasia: the commonest form, with affected muscles replaced by fibrous and fatty tissue and usually normal intelligence.
- Typical pattern: extended, fixed elbows, flexed wrists with ulnar deviation, flexed, abducted and externally rotated hips, extended knees and clubfoot.
- Shoulder: internal rotation and adduction contractures limit reaching and hand-to-mouth activity.
- Hip dislocation: common, often bilateral, and needing early attention to protect the hip joint.
- Causes: neuropathic and myopathic disorders, intrauterine constraint and fetal akinesia, so the cause must be sought in each child.
- Management principle: stretching and casting come first, with soft tissue release, tendon transfers or osteotomies once passive correction has reached its limit.
A treatment sequence for a newborn with stiff limbs
A newborn has fixed elbows, clubbed feet and hips that will not abduct. The aim is to restore a useful range of motion early, before the joints become permanently fixed.
- Document every joint: record each contracture and its range of motion, and look for associated spinal, cardiac and facial anomalies.
- Find the cause: neurological examination, nerve conduction studies, muscle biopsy and genetic testing separate neuropathic, myopathic and fetal akinesia patterns.
- Start stretching: passive stretching by parents and therapists begins in the newborn period, moving each joint gently to its available range.
- Apply serial casts: casts are applied to the elbows, knees and feet in sequence, with each cast gaining a little more range.
- Protect the hip: abduction positioning is used, and a dislocated hip is reduced surgically when splinting fails to hold the joint.
- Operate when passive correction plateaus: soft tissue release, tendon transfers and osteotomies are planned to restore function, often in later childhood.
Where the exam tries to catch you
Viva questions focus on the definition, the commonest form and the order of treatment.
- Trap: labelling arthrogryposis as a single disease with one cause. Correct: it is a clinical sign with many causes, including neuropathic, myopathic and intrauterine constraint patterns.
- Trap: assuming intellectual disability in amyoplasia. Correct: amyoplasia usually has normal intelligence, so the child needs stimulation and education rather than a presumption of disability.
- Trap: starting surgery first in a stiff child. Correct: early stretching and serial casting come first, and surgery is reserved for contractures that stop responding to conservative care.
Frequently asked questions
What is amyoplasia, and how does it differ from other forms of arthrogryposis?
Amyoplasia is the commonest form of arthrogryposis multiplex congenita, in which the affected muscles are replaced by fibrous and fatty tissue. Unlike the neuropathic or myopathic forms, amyoplasia usually has normal intelligence and a non-progressive course.
What is the typical limb pattern in arthrogryposis multiplex congenita?
Arthrogryposis multiplex congenita typically produces extended, fixed elbows, flexed wrists with ulnar deviation, hips held flexed, abducted and externally rotated, and extended knees with clubfoot. The pattern varies in severity from one child to another.
Why are stretching and casting used before surgery in arthrogryposis?
Early stretching and serial casting correct contractures while the joints are still supple, and they can reduce the need for surgery. Soft tissue release, tendon transfer or osteotomy is reserved for contractures that do not respond to conservative care.
What causes arthrogryposis multiplex congenita?
Arthrogryposis multiplex congenita has several causes, including neuropathic and myopathic disorders, intrauterine constraint and drug or teratogenic exposure. Because it is a clinical description, the cause must be sought through neurological, muscle and genetic evaluation in each child.