Etiology and classification
The disease remains not fully understood. Currently, medicine considers three main theories regarding its origin:
- Mechanical: fetal development is disrupted due to external physical factors, such as oligohydramnios, polyhydramnios, or abnormal intrauterine positioning.
- Infectious: the pathogen (amniotic infection) invades the embryo's central nervous system in early stages — approximately at the 4th–5th week of development.
- Hereditary: supported by documented cases of familial inheritance.
Depending on the extent of tissue involvement, arthrogryposis is divided into several forms. The most severe is generalized arthrogryposis, affecting the muscles and joints of the entire body, including the jaw, neck, and trunk. Other forms include involvement of all four limbs, isolated involvement (upper or lower limbs only), or involvement of a single segment.
Symptoms and clinical paradoxes
The appearance of a child with the typical form of the pathology is highly specific. Lesions commonly affect the distal parts of the limbs (hands and feet), resulting in radial or ulnar clubhand and atypical clubfoot.
In upper limb involvement, the arms appear slender due to muscle atrophy, with the shoulders pressed against the body and internally rotated. The elbows are typically fixed in extension, and the hands are flexed toward the forearms. The fingers are straight, thin, gathered together, and deviated, with the thumb often tucked beneath the others. Some patients develop a "claw hand" deformity (hyperextension at the metacarpophalangeal joints and flexion at the interphalangeal joints).
A crucial feature of the disease is the clinical paradox. The patient's functional capabilities are determined not by the angle of joint deformity, but by the state of the muscle tissue:
- If contractures are massive but muscles are preserved, the patient will be able to move actively within the available range of motion.
- If muscles are severely hypoplastic, the patient remains completely helpless even with minimal contractures.
Features of lower limb involvement
The lower limbs are affected no less severely. Complex flexion-abduction-external rotation contractures develop in the hip joints, frequently accompanied by hip dislocations. Unlike typical dysplasia, these dislocations are of embryonic origin and are fully formed by birth. Pronounced spinal hyperlordosis is also observed.
Flexion contractures predominate in the knee joints, though extension contractures also occur, up to and including subluxation of the tibia with hyperextension. The feet are almost always affected: a rigid, treatment-resistant clubfoot develops.
Principles of Diagnosis and Treatment
Diagnosis is established based on the striking clinical presentation immediately after birth. Radiography confirms joint incongruity and dysplasia, deformities, bone tissue atrophy, and osteoporosis.
Treatment of arthrogryposis is extremely challenging because the deformities are highly resistant and rigid. Physicians aim to cover all affected areas with therapy as comprehensively as possible.
A multidisciplinary approach includes:
- The use of serial plaster casts to correct the wrist joints.
- Special orthopedic positioning devices (e.g., for shoulder abduction).
- Redressive gymnastics and general massage.
It is impossible to completely eliminate the consequences of the disease; the prognosis only allows for partial restoration of function. The main goal of orthopedic surgeons is to restore the weight-bearing and statics function of the lower limbs so the patient can stand and walk.
Briefly: answers to topical questions
What pathomorphological changes at the tissue level occur in muscles in arthrogryposis?
In arthrogryposis, hypoplasia of the muscle tissue and pronounced muscle atrophy are observed.
What types of surgical interventions are used to correct contractures in arthrogryposis?
Various surgical interventions on the upper and lower limbs are used for the surgical correction of contractures and deformities in arthrogryposis. The list of main surgical methods includes:
- Shoulder arthrodesis — intervention on the shoulder joint.
- Elbow arthrolysis — operations on the elbow joint.
- Wrist arthrodesis — stabilization of the wrist joint.
- Derotational osteotomy — correction of the forearm bones.
- Soft tissue procedures — surgical interventions on the hand.
- Open reduction of the femoral head — operations on the hip joint.
- Corrective femoral osteotomies — interventions in the subtrochanteric and supracondylar regions.
- Knee arthrolysis — operations on the knee joint.
- Myotenoligamentotomies — interventions in the popliteal region.
- Corrective procedures — interventions on the feet.
To remember the typical arm posture in arthrogryposis, imagine a "doll with rusted joints": shoulders pressed to the sides, elbows non-bendable (straight), hands tucked in, and thin fingers deviated to one side.
Class and exam questions
What is more important for the prognosis of motor activity: the severity of joint involvement or the condition of the muscles?
The condition of the muscular system plays a decisive role. When muscles are preserved, active movements are possible even in the presence of severe joint contractures.
How does hip dislocation in arthrogryposis differ from typical congenital dislocation?
In arthrogryposis, dislocations occur in the early stages of intrauterine development (embryonic) and are fully formed by the time of birth.
Can arthrogryposis be completely cured?
Unfortunately, deformities are extremely rigid due to profound changes in all tissues. Treatment allows only partial restoration of limb function, focusing on the ability to independently bear weight on the legs.
What else to study on this topic
- Features and differences of atypical clubfoot in arthrogryposis versus idiopathic clubfoot
- Radiological signs of joint dysplasia and incongruity
- Technique of serial casting for contractures
- Surgical treatment of embryonic hip dislocations
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