Ligamentum teres injury

Ligamentum teres injuries or ligamentum capitis femoris injuries are a cause of hip pain and comprise complete, partial, degenerative tears as well as bony avulsions of the ligamentum teres of the hip.

Epidemiology

Ligamentum teres injuries are considered a more common cause of hip pain and are discovered on hip arthroscopy with a wide frequency up to 50% ^1,2. Partial tears are more frequent than complete tears ².

Risk factors

Activities considered as predisposing factors for ligament teres injuries include sports with high impact or twisting movements such as ^1,3:

• American football or rugby
• ice hockey
• skiing
• dancing, martial arts
• hip surgery

Associations

A ligament teres injuries might be associated with the following clinical conditions ¹:

• anterior capsular tears
• hip instability
• hip dislocation

Diagnosis

The diagnosis is challenging due to a lack of specific symptoms poor visualization on imaging. MR arthrography is considered the best imaging method ^2,3. The findings can be then confirmed on arthroscopy ².

Clinical presentation

Signs and symptoms are non-specific and include hip pain or groin pain possibly associated with a snapping sensation. A careful history of the injury mechanism might raise suspicion for a ligamentum teres injury ¹. A painfully reduced range of motion, joint locking or painful straight leg raise test might be found on clinical examination ².

Complications

If untreated ligamentum teres injuries might lead to persistent pain and instability.

Pathology

Bony avulsions, complete and partial tears as well as degenerative tears or ligament strain are considered ligament teres injuries ^1,3. Traumatic complete and partial tears are most commonly found close to the fovea capitis ¹.

Etiology

An important cause of ligamentum teres injury is a traumatic hip dislocation, other mechanisms comprise flexion adduction injuries e.g. a fall on the ipsilateral knee or hyperabduction mechanisms especially if combined with excessive external or internal rotation e.g. within the scope of a sudden twisting injury ¹.

Radiographic features

MRI

The ligamentum teres of the hip can be depicted in axial, coronal and oblique axial images. MRI with leg traction can further improve the delineation of the ligament and allow for better visualization of the articular surfaces ¹. Complete tears might reveal themselves as discontinuity, displacement or redundancy in the setting of an acute injury or as an absence of the ligament in case of a chronic complete tear ^1-4.

Partial tears a harder to detect and diagnose. Ligament thickening, irregularities, intrasubstance fluid signal intensity and loss of the smooth contours can indicate the diagnosis ^1-4.

Mucinous degeneration might include hyperintense signal changes of the ligament on T1 and T2 weighted images. Acute bony avulsions should show associated bone marrow edema ¹.

MR/CT arthrography

MR or CT arthrography better show contour alterations and fluid-filled defects and are more accurate than conventional MRI ^1-3.

Radiology report

The radiological include a description of the following:

• type and extent of the injury
• bony avulsions and/or fractures
• labral tear or chondral injury
• synovitis

Treatment and prognosis

Ligamentum teres injuries are mostly managed arthroscopically with debridement, radiofrequency ablation and depending on the type and any associated injuries capsular plication, suture or reconstruction ^1,5.

Differential diagnosis

Conditions that might mimic the imaging appearance of a ligamentum teres injury include:

• congenital absence of the ligamentum teres
• hip microinstability
• carpet lesion