Distal arthrogryposis is a group of conditions characterized by joint deformities, known as contractures, that are present at birth. The term “arthrogryposis” originates from Greek words meaning “joint” and “crooked” or “hooked.” These contractures primarily affect the hands and feet, limiting the range of motion. While congenital, the condition typically does not worsen over time in terms of stiffness.
Recognizing Distal Arthrogryposis
Babies born with distal arthrogryposis often exhibit specific physical signs in their hands and feet. These can include permanently bent fingers and toes, known as camptodactyly. Overlapping fingers and a hand deformity where all fingers angle outward toward the fifth finger, called ulnar deviation, are also common.
Another frequent manifestation is clubfoot, which presents as an inward and upward turning of the foot. The combination and severity of these hand and foot abnormalities can vary significantly. While joint movement is affected, intellect and the function of other body systems are typically not impacted.
Understanding the Causes
Distal arthrogryposis stems from genetic factors, with mutations in specific genes as the underlying cause. Genes such as MYH3, TPM2, TNNI2, and TNNT3 are frequently implicated. These genes play a role in the formation and function of muscle cells, particularly those involved in muscle contraction.
The inheritance pattern for most forms of distal arthrogryposis is autosomal dominant, meaning one copy of an altered gene is sufficient to cause the disorder. The condition can be passed down from a parent who carries the altered gene, or it can arise as a new genetic mutation. Distal arthrogryposis is not caused by anything a parent did or did not do during pregnancy.
Diagnosis and Treatment Approaches
Diagnosis typically begins with a clinical examination at birth, observing characteristic joint contractures in the hands and feet. Genetic testing confirms the diagnosis and identifies the specific type, pinpointing mutations in genes such as MYH3, TPM2, TNNI2, and TNNT3.
Treatment focuses on improving joint mobility and maximizing functional independence. Therapeutic interventions include physical therapy and occupational therapy, involving stretching exercises to increase range of motion and strengthen muscles. Serial casting, where casts are periodically changed to gradually stretch and reposition joints, is often used, particularly for clubfoot.
Bracing may also maintain corrected joint positions after stretching or casting. In some instances, surgery may be considered to release tight tissues or to improve the alignment and function of affected joints. This comprehensive approach aims to help individuals achieve the best possible physical abilities, including walking and performing daily self-care activities.