Ligament

a fibrous band that connects bones and cartilage. Ligaments resemble tendons histologically and biomechanically and have similar attachment sites (enthesis). Various ligaments are discussed under their specific names (e.g. ligamentum nuchae).

2. Pathology

Ligaments may be damaged in numerous musculoskeletal disorders, or they may play an etiological role in some diseases. In rheumatoid arthritis, as one example, significant abnormalities of ligaments and tendons contribute to the typical joint deformities that accompany disease of long duration. Boutonniere deformity results from an imbalance in normal tendon, and ligament and joint relationships. In the spine, anterior atlantoaxial subluxation is sometimes the result of transverse ligament laxity due to synovial inflammation and hyperaemia of the adjacent joints.

Other spinal ligaments are involved prominently in certain diseases. One characteristic disorder of the spine is ossification, which may lead to significant neurologic findings. In this condition, a linear band of ossification is observed on radiographs to extend along the posterior margin of vertebral bodies and intervertebral discs, particularly in the cervical spine. Another disorder involves bone proliferation at the cephalad and caudad attachments of the ligamentum flavum. Although this finding is common and is generally of no significance, some cases are more serious, with neurological manifestations and sometimes diffuse idiopathic skeletal hyperostosis. Calcification may also be observed in the ligamentum flavum as a result of deposition of calcium hydroxyapatite or calcium pyrophosphate dihydrate crystals. Hyperostosis at the site of attachment of the supraspinous ligament to bone and calcification in the interspinous ligament are additional abnormalities of the posterior spinal tissues.Calcification and ossification within the anterior longitudinal ligament are present in diffuse idiopathic skeletal hyperostosis.

Various ligamentous injuries in other sites may lead to mild or serious defects. Ligament tears or ruptures are widely distributed and are particularly noteworthy about the wrist, ankle, elbow and knee. In these cases, plain film radiography may require supplementation with stress radiography. In the knee, tears of the collateral ligament and anterior cruciate ligament may be assessed with arthrography. Abnormal findings are frequently subtle, however. Stress radiographs are especially helpful in the investigation of ligamentous injuries of the knee and the ankle; but MR imaging holds greatest promise for noninvasive assessment of ligaments. In the ankle, the anterior talofibular ligament, calcaneofibular ligament, distal anterior tibiofibular ligament and deltoid ligament may also be torn or otherwise injured. Any of these ankle injuries may be associated with abnormalities on plain films, including soft tissue swelling and avulsion fractures at the osseous sites of attachment of the specific ligaments. Ligament disruptions about the elbow can accompany severe physical trauma (e.g. elbow dislocation) or occur as a response to less extensive acute trauma (e.g. valgus injury) or chronic stress (e.g. pitching a baseball).

In degenerative disease of the spine, degeneration may become evident in various spinal ligaments, including the anterior longitudinal ligament, the posterior longitudinal ligament, the ligamenta flava, the interspinous, supraspinous and intertransverse ligaments, the ligamentum nuchae, and the iliolumbar ligaments. Supraspinous and interspinous ligament abnormalities frequently coexist. Kissing spines such as are seen when ligaments degenerate may develop reactive eburnation (Baastrup's disease).
In Pellegrini – Stieda syndrome, ossification of the medial collateral ligament of the knee occurs after trauma.

DR

DR