The ligamentum teres is a small but highly significant structure deep within the hip joint. Advances in imaging and surgical techniques show this cord of tissue is a frequent contributor to hip pain and instability. Its function is now understood to be complex, making it an important focus for diagnosing deep groin pain and mechanical symptoms.
Structure and Location
The ligamentum teres is an intra-articular ligament situated deep within the hip joint. It connects the femoral head (the “ball”) to the acetabulum (the “socket”). Specifically, the ligament originates from the acetabular notch and the transverse acetabular ligament, attaching to a shallow depression on the femoral head called the fovea capitis.
The structure typically measures between 30 and 35 millimeters in length, though its size can vary considerably among individuals. It is often described as a flattened or pyramidal shape at its origin, transitioning into a more cord-like structure at its insertion. The ligament is encased in a synovial sheath and is composed primarily of a dense network of collagen fibers, fibrous tissue, and fat.
The ligamentum teres serves as a conduit for the foveal artery, a branch of the obturator artery. While this artery supplies blood to the femoral head in infancy, its contribution in the adult hip is considered negligible. The ligament also contains small nerve bundles that relay information about joint position and movement back to the nervous system.
Developmental Origin and Function
Historically, the ligamentum teres was considered a vestigial, non-functional remnant. However, increased use of hip arthroscopy has prompted a re-evaluation of its role. The ligament is now recognized as having both mechanical and biological functions that contribute to overall hip health.
In the adult, the ligament acts as a secondary stabilizer, limiting excessive hip movement, especially at extremes of rotation. It becomes taut when the hip is flexed, adducted, and externally rotated, stabilizing the joint in a vulnerable position. The nerve endings within the tissue suggest it plays a part in proprioception, providing feedback about the hip’s position in space.
Common Conditions Affecting the Ligament
The ligamentum teres can become a source of pain when damaged, with the most common pathology being a tear. These tears can be partial, involving only some of the fibers, or a complete rupture of the entire structure. Injuries often occur due to high-energy trauma, such as a hip dislocation, or from repetitive microtrauma over time.
Repetitive twisting motions and activities that demand extreme hip flexibility, such as dancing or gymnastics, place the ligament under stress and increase the risk of injury. Tears are also frequently found alongside other hip conditions, including femoroacetabular impingement (FAI) and hip dysplasia. Chronic instability from these underlying structural issues can cause the ligament to fray and tear.
Symptoms of damage often include persistent deep groin pain that worsens with movement or prolonged sitting. Patients may also experience mechanical symptoms such as clicking, catching, or a feeling of the hip giving way, indicating joint instability. Chronic irritation can also lead to hypertrophy (thickening of the ligament) or synovitis (inflammation of the surrounding joint lining).
Clinical Diagnosis and Treatment
Diagnosis
Diagnosing a ligamentum teres injury is challenging because its symptoms often overlap with other hip pathologies, and no single physical examination test is definitive. A clinician performs a thorough physical assessment that includes maneuvers designed to stress the ligament, checking for pain with specific rotational and flexed movements. Imaging plays a necessary role in confirming the diagnosis and ruling out other sources of pain.
Magnetic Resonance Imaging (MRI), particularly when combined with an injection of contrast dye (MR arthrogram), is the most effective non-invasive method for visualizing the soft tissue. However, hip arthroscopy, which involves inserting a small camera into the joint, remains the gold standard for definitive diagnosis and classifying the extent of the damage. This allows the surgeon to directly visualize the tear or inflammation.
Treatment
Treatment for mild cases or partial tears begins with non-operative management. This conservative approach includes rest, modification of activities, and the use of non-steroidal anti-inflammatory drugs (NSAIDs) to reduce pain and inflammation. Physical therapy is also important, focusing on strengthening the muscles around the hip to improve stability and control.
If conservative methods fail, or for complete ruptures, surgical intervention is often required and is typically performed arthroscopically. The most common procedure is debridement, where the surgeon trims the frayed, damaged tissue to eliminate mechanical irritation. In rare cases of gross hip instability, a complete reconstruction of the ligament using a tissue graft may be considered.