Syndesmoses

Syndesmoses are a type of fibrous joint in which two adjacent bones are joined by ligaments or an interosseous membrane, resulting in limited or restricted movement and no joint cavity. In anatomy, the plural form syndesmoses refers to these joints, which rely on dense connective tissue to bind the bones together.

Structure and examples

A syndesmosis may be formed by a sheet-like interosseous membrane or by a set of short ligaments linking the bones. Classic examples include the interosseous membranes between the radius and ulna and between the tibia and fibula, as well as the distal tibiofibular syndesmosis at the ankle, where the tibia and fibula are connected by the anterior and posterior inferior tibiofibular ligaments and an interosseous ligament. These joints lack a true articular cavity and exhibit little intrinsic motion, serving primarily a stabilizing role.

Function

Syndesmoses provide stability and help distribute load between adjacent bones, while permitting only minimal motion to accommodate growth, rotation, or stress. The interosseous membranes also serve as sites for muscle and tendon attachments and contribute to the mechanical integrity of the forearm and lower leg.

Clinical relevance

Injuries to a syndesmosis, such as a high ankle sprain involving disruption of the distal tibiofibular ligaments, can lead to diastasis or instability of the distal leg. Accurate assessment often requires imaging, and management ranges from immobilization to surgical repair, depending on severity.

Development and biomechanics

Syndesmoses arise from fibrous connective tissue and persist into adulthood, maintaining the alignment and stability of the connected bones. Their biomechanics emphasize stability over mobility, with load transfer and rotational control playing key roles in joint function.