Syndesmosen

Syndesmosen, also known as syndesmosis, is a type of fibrous joint in which two adjacent bones are joined by a ligamentous connection or by an interosseous membrane. This arrangement binds the bones more rigidly than a typical synovial joint and allows only small, controlled amounts of motion. The joint lacks a true synovial cavity and relies on dense connective tissue for stability.

In anatomical terms, syndesmoses occur wherever two long bones are bound along their length by interosseous membranes or strong ligaments. The best-known example is the distal tibiofibular syndesmosis, where the tibia and fibula are connected by the interosseous membrane and the anterior and posterior tibiofibular ligaments. Similar interosseous connections exist between the radius and ulna in the forearm. Syndesmotic connections also occur between other paired bones where a robust ligamentous or membranous link stabilizes adjacent bones.

Functionally, syndesmoses provide stability for adjacent joints and facilitate force transmission across the limb while permitting limited adaptive movement during activities such as walking or running. They help maintain alignment of the bones under load and during rotational or dorsiflexion movements.

Clinical relevance centers on syndesmotic injuries, commonly termed high ankle sprains, which can disrupt the tibiofibular ligaments and interosseous membrane. Diagnosis uses physical examination and imaging (X-ray, MRI). Treatment depends on severity and may range from immobilization and rehabilitation to surgical fixation (e.g., screws or suture-button devices) in unstable cases. Recovery depends on injury extent and healing of the ligamentous structures.