Definition
AMC characterised by non progressive congenital rigidity of 2 or more joints
Types
1. Amyoplasia
- involves all 4 limbs
2. Distal arthrogryposis
- autosomal dominant
- type 1 98% hand / 87% feet
- type 2 involve other systems
Epidemiology
1 in 3000 live births
Etiology
Fibrosis of periarticular soft tissues during joint development
Incomplete fibrous ankylosis
Unknown cause / numerous theories
Pathology
Muscles replaced by fibrous tissue
Spinal cord decreases in size, especially at the limb enlargements
- decreased number of anterior horn cells
Clinical
Usually involves all 4 limbs (AMC)
Marked limitation of joint ROM
No skin creases
Upper limb
- shoulders adducted and internally rotated
- elbows extended
- wrists flexed, pronated & ulna deviation
Lower limb
- hips flexed, externally rotated & abducted / dislocated
- knees flexed
- patella dislocation
- equinovarus
Scoliosis
Management
Principles
Lower limbs by age of 2 to allow walking
- plantigrade feet
- knee extension
- hip reduction
Upper limbs
- delay to allow bimanual function
- ability to bring hand to mouth / elbow flexion
- ability to toilet & push off when rising with other hand
Lower limb
Equinovarus
Posteromedial release + AFO's
Triple arthrodesis
Knee flexion contracture
Splinting
Surgical release - capsule + hamstring lengthening
Supracondylar osteotomy
Hip Dislocation
Open reduction ± femoral shortening & derotation osteotomy age 1
Old children may be best to leave
Upper limb
Hand
Little to offer for severe deformity
Wrist flexion
Hand stiffness
Non operative
Pronated flexed wrist enables forearm radial borders to appose each other to produce pincer grip
Wrist flexion
Dorsal closing wedge capitate / FCU transfer
Carpectomy
Wrist fusion
Shoulder Internal rotation
External rotation osteotomy in proximal shaft
Elbow Extension
Need one elbow bent & one straight
Unilateral posterior capsulotomy + triceps transfer + steindler flexorplasty
Scoliosis
Brace
Fusion
