What is arthrogryposis? Definition
The term arthrogryposis does not identify a specific syndrome, but a clinical characteristic, namely congenital multiple joint contracture (from the Greek “ Arthron ”, joint, and “ Grypos ”, rigid), which involves two or more anatomical districts , and which can be found in different pathological conditions, with different etiologies.
Unfortunately, this term, as well as the terms “Arthrogryposis Multiplex Congenita” and amyoplasia, have often been used with different meanings by different authors, thus generating some confusion.
Arthrogryposis: classification and causes
The attempt to classify (from an etiological, pathogenetic and molecular point of view) the different conditions is not easy, and is constantly evolving, in light of the ongoing research carried out in the molecular and genetic fields.
The causes that can cause it are largely unknown, but are presumed to be multifactorial .
Potential causes may be:
- neuropathic (Central Nervous System, spinal cord, peripheral nerve)
- myopathic (muscular dystrophies, mitochondrial abnormalities)
- connective tissue abnormalities (dystrophic dysplasia, etc.)
- intrauterine problems (space limitations, maternal factors, etc.)
- alterations in intrauterine or fetal circulation
- other
The common thread among these different hypothesized etiologies appears to be the absence of fetal movement, which would lead to collagen proliferation and muscle replacement with fibrous tissue. For this reason, conditions with different ethologies can lead to very similar clinical presentations, which may also require similar treatments (rehabilitative, orthotic, and surgical).
For this reason, it is necessary from the very beginning to ensure that the diagnostic tests and treatment (physiatric/orthopedic) proceed in parallel.
The analysis of the various tests required for a diagnostic assessment (clinical examination, CK, EMG, muscle biopsy, genetic tests, etc.) is carried out in collaboration with experienced neuropediatricians and clinical geneticists, and is beyond the scope of this document.
However, for clinical purposes, it may be useful to distinguish between:
A- forms of arthrogryposis with abnormal neurological function:
- CNS pathologies (malformations, genetic anomalies, etc.)
- neuromuscular diseases (SMA with arthrogryposis, congenital peripheral neuropathies, congenital myopathies, congenital muscular dystrophies, etc.) which will imply specific diagnostic approaches and different functional prognosis, and
B- forms of arthrogryposis with normal neurological function : amyoplasia, distal arthrogryposis, connective tissue disorders, fetal compression pathologies
Amyoplasia or “classic” Arthrogryposis
The term amyoplasia (others use the term “Classic Arthrogryposis”) refers to the most common, sporadic form characterized by symmetrical involvement of the limbs, normal intelligence, a typical clinical picture (adducted and internally rotated shoulders, extended elbows, flexed and ulnarized wrists, stiff fingers, thumbs in the palm, stiff and often dislocated hips, often hyperextended knees, clubfeet), often a facial angioma.
Distal Arthrogryposis
They represent a group of arthrogryposis characterized by autosomal dominant genetic transmission and predominant involvement of the distal limbs (hands and feet), with variable expressivity. There are several forms (e.g., type 2A, Freman-Sheldon syndrome).
