Arthrogryposis Multiplex Congenita (AMC)

Question 1

AMC

Answer 1

non-progressive neuromuscular syndrome present at birth

Characteristics: severe joint contractures, mm weakness, fibrosis

Long term sequelae can be disabling

Activity limitations in mobility, self-care –> can lead to participation restrictions

PT needs to maximize child’s independence

Question 2

Incidence and Etiology

Answer 2

AMC defined: contractures in 2 or more body areas

1 in ever 3-6,000 births

Cause is unknown- insult believed to occur in 1st trimester

Contractures likely to be caused by lack of fetal mvmt

Amyloplasia = most common form on AMC

Children with congenital contractures fall into the following categories:

• amyloplasia
• related to CNS- lethal
• heterogeneous group- neuromuscular syndromes, congenital and chromosomal abnormalities, contracture syndrome and skeletal dysplasia

Distal Arthrogryposis- hands feet, highly responsive to rx, genetic basis- inherited autosomal dominant trait, chromosome 9

AMC associated with neurogenic and myopathic disorders–> motor weakness leads to decreased fetal movement and causes contractures

Neurogenic– degeneration of anterior horn cell, chromosome 5

Decreased amniotic fluid = decreased fetal mvmt = possible contractures

Proposed causes: maternal fever, viral infection, vascular compromise, uterine fibroid tumors, septum in uterus

Question 3

Primary Prevention: 6 Categories of problems that can occur during pregnancy that result in lack of fetal mvmt

Answer 3

Maternal illness
fetal crowding
neurologic deficits
vascular compromise
connective tissue/skeletal defects
muscle defects

Question 4

Diagnsosis

Answer 4

No definitive lab tests prenatally; contractures must occur in 2 or more different body areas

AMC has been linked to chromosome 5, 9. 11

Most cases occur sporadically

Contractures present at birth but DX might not be given at that time

If suspicious of problems complete Level II US to identify fetal anomalies and decreased mvmt

Dx of AMC prenatally mother can perform deep breathing, light exercise, and caffeine to help stimulate baby—need to be cleared by physician

Question 5

Clinical Manifestations

Answer 5

Variable
Severe joint contractures, lack of mm development or amyoplasia

Body parts affected:
foot > hip > wrist > knee > elbow > shoulder

Two Variations of AMC:

1. Flexed and dislocated hips, extended knees, clubfeet (equinovarus), IR shoulders, flexed elbows, flexed/ulnar deviated wrists
   - –jackknifed le’s
2. Abducted/ER hips, flexed knees, clubfeet, IR shoulders, extended elbows, flexed/ulnar deviated wrist
   - –frog leg le’s, waiter’s tip ue

Other characteristics:
scoliosis, dimpling of skin over joints, hemangiomas, absent/decreased finger creases, congential heart disease, facial abnormalities, respiratory probs, abdominal hernias

Normal intelligence and speech

May also have abnormal mm tone, webbing contractures, changes in cognition, seizure, feeding issues, and limited visual skills

Question 6

Med Mgmt 
 Feet
 Hips
 Knee
 Shoulder
 Wrists
 Spine

Answer 6

Surgical intervention- times so that child can benefit optimally from procedure (i.e. club foot surgery)

Clubfoot can be recurring problem even after surgery

• • ponsetti brace or serial casting attempted before surgery
• -Ilizarov procedure- external fixator for rx of recurring club foot

Hip dislocations- surgical open reduction

• -if bilateral dislocation may not repair due to risk of obliquity
• -greatest success for hip surgery occurs in 1st year of life
• -prolonged immobilization can lead to secondary impairment of stiff or fused hips

Knee Flexion- contractures treated first conservatively

• -hamstring lengthening– inconsistent success
• -distal femoral osteotomy more successful than lengthening due to less scar tissue formation and change in arc of motion

Knee extension- associated with patellar subluxation

• • patellar realignment done before age 5 to promote
• -Later in life may need quad lengthening surgery
• -surgery completed if child is having difficulty sitting or walking

Shoulder- rarely addressed through surgical intervention

Wrists- fusion treated first with splinting, casting and stretching before surgical intervention

Scoliosis- managed conservatively with bracing

• -1/5 of AMC develop C-shaped thoracolumbar curve
• • if curve continues to progress = surgical intervention