Arthrogryposis Multiplex Congenita (AMC): Serial Splinting, Contracture Management, and Mobility Protocols
In short
Arthrogryposis Multiplex Congenita involves non-progressive congenital joint contractures; aggressive early serial splinting and gentle passive stretching maximize independence.
In this guide (4 sections)
Pathophysiology and Fetal Akinesia in Arthrogryposis
Arthrogryposis Multiplex Congenita (AMC) is a descriptive clinical diagnosis defined by congenital, non-progressive joint contractures involving two or more distinct body areas present at birth. While over 400 specific underlying conditions can cause AMC, the most common classical form is Amyoplasia ('lack of muscle development', accounting for roughly 30% of cases), characterized by symmetrical limb involvement with fibrous and fatty replacement of skeletal muscle.
The shared pathogenic mechanism underlying all AMC forms is Fetal Akinesia (decreased or absent intrauterine movement). Normal fetal movement is mandatory for joint cavity development and periarticular connective tissue elongation. When fetal movement is compromised (due to maternal illness, oligohydramnios, anterior horn cell loss, or primary myopathy), joint capsules, ligaments, and tendons fail to lengthen, condensing into dense, rigid collagenous contractures.
Clinical Presentation Matrix by Classical Amyoplasia Types
| Anatomical Joint Segment | Classical Congenital Deformity Posture | Contracture Characteristics | Functional Impairment Challenge | |
|---|---|---|---|---|
| Shoulders | Adducted and internally rotated | Rigid anterior capsule contracture | Severe restriction in hand-to-mouth reach | |
| Elbows | Fixed extension (60%) or fixed flexion (40%) | Triceps / biceps fibrous bands replace muscle | Extended elbows cannot reach mouth; flexed elbows cannot push up | |
| Wrists & Hands | Flexed and ulnarly deviated wrists; flexed fingers | Athetoid-like appearance with webbed skin folds | Grip and pinch grasp severely impaired | |
| Hips | Flexed, abducted, externally rotated; dislocation risk | Teratologic hip dislocation in 30% to 40% | Blocks upright standing alignment and weight-bearing | |
| Knees | Fixed flexion contracture or fixed hyperextension | Pterygium (popliteal skin webbing) in severe types | Flexion contracture > 20 deg blocks functional walking | |
| Feet | Severe rigid bilateral clubfeet (equinovarus) | Resistant to standard casting; vertical talus common | Precludes flat shoe-wearing and ground weight-bearing |
Standardized Clinical Physiotherapy and Serial Splinting Protocols
- Low-Load Prolonged Passive Stretching Protocols: Execute gentle, slow, low-load prolonged passive stretching across all contracted joints for 3 to 5 repetitions per joint, holding each stretch for at least 30 to 60 seconds; never use aggressive, jerky, high-velocity forces that risk tearing fragile tendons or fracturing osteopenic bone.
- Serial Remoldable Thermoplastic Night Splints: Fabricate custom low-temperature thermoplastic splints for wrists, elbows, and knees; remold splints every 2 to 3 weeks to capture progressive angular gains achieved during daily stretching sessions; mandate nighttime and naptime wear.
- The Strategic Functional Elbow Goal: In children with fixed extended elbows, prioritize surgical release or passive stretching to achieve at least one flexed elbow (for self-feeding and grooming) while leaving the opposite elbow in extension (for pushing up from chairs and perineal hygiene).
Frequently Asked Questions
What is Arthrogryposis (AMC) in newborns?
Arthrogryposis means a baby is born with stiff, curved joints that cannot bend or straighten normally. It happens when the baby was unable to kick and move around freely inside the womb, causing the joints to lock in stiff positions before birth.
Does arthrogryposis get worse as a child gets older?
No! Arthrogryposis is non-progressive, meaning it does not spread or get worse over time. In fact, with daily stretching, gentle splinting, and physiotherapy, children consistently gain more flexibility, learn to walk, and become remarkably independent.
Why do therapists want one arm to bend and one arm to stay straight?
This is a clever functional strategy! If both arms are stiff, having one elbow that bends allows the child to bring a spoon to their mouth and brush their teeth, while keeping the other elbow straight allows them to push up out of a chair.
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