Ligamentum Teres: Anatomy, Function, Injuries, and Treatment

What is ligamentum teres?

The ligamentum teres, also known as the round ligament of the femur, is a small but significant intra-articular ligament located within the hip joint, connecting the head of the femur to the acetabulum. Despite its size, it plays a role in hip joint stability and serves as a conduit for a crucial blood supply to the femoral head, particularly during childhood.

Anatomy and Location

The ligamentum teres is a unique anatomical structure situated entirely within the joint capsule of the hip, specifically within the acetabular fossa. While intra-articular, it is extrasynovial, meaning it is surrounded by a synovial sheath but not directly bathed in synovial fluid.

• Origin and Insertion: This ligament originates from the transverse acetabular ligament and the margins of the acetabular notch, then extends to insert into the fovea capitis, a small depression on the head of the femur.
• Structure: It typically presents as a flattened, triangular, or somewhat cylindrical band of connective tissue. Its primary composition is collagen fibers, providing tensile strength, along with a small amount of elastic tissue.
• Neurovascular Content: A critical aspect of the ligamentum teres is its neurovascular bundle. It typically encases the foveal artery (also known as the artery of the ligamentum teres), which is a branch of the obturator artery, although its origin can vary. This artery provides a significant blood supply to the femoral head, especially during early development. In adults, its contribution to femoral head vascularity diminishes, but it remains a potential collateral supply. The ligament also contains sensory nerve endings, suggesting a proprioceptive role in hip joint position and movement.

Function and Role

Historically, the ligamentum teres was often considered a vestigial structure with minimal functional importance in adults. However, contemporary understanding, supported by biomechanical research and clinical observations, has revealed its multifaceted roles:

• Secondary Hip Stabilizer: While the primary stability of the hip joint is provided by the strong capsular ligaments (iliofemoral, pubofemoral, ischiofemoral), the ligamentum teres contributes to secondary stability. It becomes taut during specific movements, particularly hip adduction, flexion, and external rotation, helping to resist excessive distraction or subluxation of the femoral head from the acetabulum. Its role in stabilizing the hip, especially in positions of near dislocation, is increasingly recognized.
• Vascular Conduit: As mentioned, it houses the foveal artery. This arterial supply is vital for the developing femoral head in children. Although its contribution lessens with age as other vascular pathways mature, it can still serve as an important collateral supply in adults, particularly in cases of injury to the main arteries supplying the femoral head.
• Proprioception: The presence of nerve endings within the ligament suggests a proprioceptive function, contributing to the brain's awareness of hip joint position and movement, thereby aiding in motor control and dynamic stability.

Clinical Significance: Injuries and Conditions

Despite its protective intra-articular location, the ligamentum teres is susceptible to injury and various pathological conditions, which are increasingly diagnosed due to advancements in imaging and arthroscopic techniques.

• Traumatic Tears: Acute tears often occur due to high-energy trauma, such as hip dislocations, direct impact to the hip, or sudden, forceful twisting movements. These can be partial or complete.
• Degenerative Tears/Degeneration: Chronic, repetitive microtrauma, often seen in athletes involved in pivoting or extreme range-of-motion sports (e.g., hockey, soccer, ballet), can lead to gradual degeneration and fraying of the ligament.
• Impingement: In some cases, the ligament can become impinged between the femoral head and the acetabulum, leading to pain and inflammation, particularly in individuals with femoroacetabular impingement (FAI).
• Hypertrophy: The ligament can sometimes become enlarged (hypertrophic), which may contribute to impingement or mechanical symptoms within the joint.
• Symptoms: Patients with ligamentum teres pathology often present with deep groin pain, which may radiate to the buttock or thigh. Other common symptoms include:
  • Clicking, catching, or locking sensations in the hip.
  • Sensation of instability or giving way.
  • Pain exacerbated by specific movements, especially hip adduction, internal rotation, or prolonged sitting.
  • Symptoms often overlap with other hip pathologies, such as labral tears, making diagnosis challenging.

Diagnosis and Treatment

Diagnosing ligamentum teres pathology can be complex due to its deep location and the non-specific nature of its symptoms.

• Clinical Examination: Physical examination may reveal tenderness in the groin or pain with specific hip movements (e.g., flexion, adduction, internal rotation). However, no single test is definitive.
• Imaging Studies:
  • X-rays: Primarily used to rule out bony abnormalities.
  • MRI (Magnetic Resonance Imaging): While standard MRI can show signs of inflammation or thickening, MR arthrography (MRA – MRI with contrast injected into the joint) is often superior for visualizing the ligament and detecting tears.
  • CT Scan: Useful for assessing bony anatomy and ruling out fractures.
• Diagnostic Hip Arthroscopy: Considered the gold standard for definitive diagnosis. During this minimally invasive surgical procedure, a camera is inserted into the hip joint, allowing direct visualization of the ligamentum teres and other intra-articular structures.

Treatment approaches vary based on the severity and nature of the injury:

• Conservative Management: For mild injuries or degeneration, initial treatment typically involves:
  • Rest and activity modification: Avoiding aggravating activities.
  • Non-steroidal anti-inflammatory drugs (NSAIDs): To reduce pain and inflammation.
  • Physical Therapy: Focusing on restoring hip range of motion, strengthening surrounding musculature (glutes, core), and improving proprioception.
• Surgical Intervention: When conservative measures fail, or for significant tears causing instability or mechanical symptoms, arthroscopic surgery may be considered:
  • Debridement: Removing frayed or degenerated tissue.
  • Repair: Direct repair of the ligament is rarely feasible for complete tears due to its structure and limited healing potential.
  • Reconstruction: In cases of significant instability due to complete tears, reconstruction using a graft (e.g., hamstring autograft) may be performed to restore stability, though this is a less common and complex procedure.

Rehabilitation and Prevention

Post-operative rehabilitation is crucial for optimal recovery following surgical intervention for ligamentum teres pathology. It typically involves:

• Phased Progression: Gradual restoration of range of motion, followed by strengthening exercises for the hip and core, and finally, sport-specific or functional training.
• Proprioceptive Training: Exercises to improve balance and joint position sense are vital for preventing re-injury.
• Gradual Return to Activity: A carefully managed return to sports or high-impact activities is essential to allow for adequate healing and strength recovery.

Prevention strategies for ligamentum teres injuries are similar to those for other hip pathologies:

• Proper Warm-up: Preparing the hip joint and surrounding muscles for activity.
• Strength and Conditioning: Maintaining strong hip abductors, adductors, and core muscles to provide dynamic stability to the hip joint.
• Flexibility and Mobility: Ensuring adequate hip range of motion without excessive strain.
• Gradual Progression: Avoiding sudden increases in training intensity or volume.
• Biomechanical Analysis: Addressing any underlying biomechanical inefficiencies that may place undue stress on the hip joint.

Key Takeaways

The ligamentum teres, once considered an anatomical afterthought, is now recognized as a relevant structure within the hip joint. It contributes to hip stability, provides a vital blood supply (especially in youth), and contains nerve endings for proprioception. Injuries to this ligament, while often challenging to diagnose, can be a significant source of hip pain and dysfunction. Understanding its anatomy and function is crucial for clinicians and fitness professionals alike in diagnosing and managing hip-related issues.