Research Review by Dr. Shawn Thistle©

Date:

Aug. 2006

Study Title:

Acetabular labral tears of the hip: Examination and diagnostic challenges

Authors:

Martin RL et al.

Publication Information:

Journal of Orthopaedic & Sports Physical Therapy 2006; 36(7): 503-515.

Summary:

Interest in intra-articular hip pathology has grown with the evolution of arthroscopic surgery. In the hip, the relation of anatomical pathology to functional limitation is still not well understood. As such, it is critical for those practicing manual medicine to possess a comprehensive and current understanding of the anatomical structures in the hip, and their relation to clinical symptoms, differential diagnosis, and management of hip and groin pain.

The hip is a complex anatomical region with intricate relations to the lower kinetic chain and core. As new research emerges, our understanding of acetabular labral tears, capsular laxity, femoral acetabular impingement (FAI), chondral lesions and acetabular dysplasia has increased.

In this paper, Martin and colleagues review anatomical and clinical considerations for the above mentioned conditions, which will be summarized in this review (NOTE: treatment issues were not reviewed in this paper). Extra-articular causes of hip pain will not be discussed here, but will be a topic for a future Research Review.

Anatomical Considerations:
  • the labrum of the hip is analogous to the meniscus of the knee or glenoid labrum of the shoulder - it assists in deepening the hip socket (thus providing stability) and maintaining negative intra-articular pressure
  • neurologically, the labrum is a rich source of proprioceptive feedback, but can also be a pain generator
  • the hip joint capsule is supported by three extra-articular ligaments - the pubofemoral (tightens during external rotation and abduction), ischiofemoral (tightens during internal rotation and abduction), and iliofemoral (tightens during external rotation and adduction) ligaments
  • in general, the hip ligaments are taut in extension and relaxed in flexion
  • articular cartilage in the hip is thicker anterosuperiorly (where most weight-bearing occurs)
Acetabular Labral Tears:
  • more common than once thought
  • can be due to repetitive microtrauma, or overt trauma - most common mechanism of injury is external rotation with forced hyperextension
  • may occur in conjunction with FAI, chondral defects, or capsular laxity (see below)
  • classified into 4 types:
    • radial
    • radial fibrillated
    • longitudinal peripheral
    • abnormally mobile
  • symptoms can include: hip or anterior groin pain, clicking, locking, catching, instability, "giving way", general stiffness
  • pain may also be referred to the buttock, greater trochanter, or medial knee
  • clinical tests can include: FABER test, scour test, and resisted straight leg raise test - overall, there is a lack of data regarding sensitivity, specificity, or likelihood ratios associated with a single test or cluster of tests for diagnosing labral tears
    • FABER test - combines hip flexion, abduction, and external rotation - positive test for intra-articular pathology is not pain production alone, location must be considered - anterior pain is more likely to be intra-articular, while posterior pain may indicate sacroiliac joint involvement (again, not much data to support this)
    • Scour test - move the femur passively through an arc of motion with hip flexion/adduction and extension/abduction while applying a compressive force to the hip joint (move clockwise and counterclockwise) - positive test is joint clicking or locking or hip pain
    • Resisted Straight Leg Raise - raise leg to 30° of hip flexion with the knee in full extension - patient resists a downward force on the leg - positive test is hip/groin pain and/or clicking or lockingc
  • if a labral tear is suspected based on history and examination findings, the practitioner should further investigate for FAI and capsular laxity (see below), or refer for imaging to investigate for chondral lesions or dysplasia (see below)
Femoral Acetabular Impingement (FAI):
  • occurs when there is decreased joint clearance between the acetabulum and the femur
  • two types have been identified:
    • cam - occurs when the femoral head has an abnormally large radius, causing a loss of normal spherical joint shape, resulting in abnormal contact (this type has been implemented in anterosuperior labral and chondral lesions)
    • pincer - an abnormal acetabulum provides "overcoverage" of the femoral head resulting in abutment of the femoral head on the acetabulum - can be general (coxa profunda) or local anterior (acetabular retriversion)
  • pincer type is thought to be more common in active middle aged women while cam type is thought to be more common in younger male athletes
  • clinical presentation often includes a "pinching" type of pain, particularly with sitting or prolonged hip flexion
  • the best available clinical test is simply called the impingement test - combining hip flexion, adduction, and internal rotation with the patient supine - positive test is pain or pinching sensation
Capsular Laxity:
  • can be traumatic or atraumatic (similar to the shoulder)
  • atraumatic instability is classified as:
    • global - occurs in individuals with connective tissue disorders (ex. Marfan's, Ehlers-Danlos, BJHS, etc.)
    • focal rotational - typically results from excessive external rotation in activities such as golf, ballet, gymnastics, martial arts, hockey, and baseball
  • labral tears can also contribute to capsular laxity and the two conditions often coexist
  • clinical tests can include: the log roll test and long-axis femoral distraction:
    • log roll test - with the patient supine and the hip in neutral position, passively roll the leg into full internal and external rotation - positive test a noticeable side-to-side difference in motion or clicking (the authors suggest that excessive external rotation is indicative of iliofemoral ligament insufficiency, while a click with internal rotation is suggestive of a labral tear)
    • long-axis femoral distraction - with the patient supine and the involved hip in 30° flexion, 30° abduction, and 10-15° of external rotation the examiner leans backward while holding the leg at the malleoli - a positive test is a feeling of apprehension or increased comparative motion
While keeping these conditions in mind, one must always remember degenerative osteoarthritis as a possible cause of hip pain. Clinically, it appears that limited internal hip rotation is the most predictive finding to suggest this as a cause of pain or symptoms (in addition to morning stiffness, age etc.).

Chondral Lesions:
  • roughly 75% of patients with labral tears have chondral damage due to increased contact pressure and articular cartilage consolidation
  • anterosuperior chondral damage has been associated with cam FAI, anterior capsular laxity, and dysplasia
Dysplasia:
  • refers to a developmental problem with the shape of the acetabulum which prevents a normal articulation from forming most common form is a shallow acetabular recess, which decreases coverage of the femoral head laterally, which reduces the bony stability of the hip
Diagnostic Testing:
  • advanced imaging - MRI and particularly MRA (magnetic resonance angiography) are the choice methods for investigating labral tears
  • other tests could include plain film radiographs, bone scan, CT scan, or ultrasound - plain films would be the least useful for detecting labral tears in this group but are useful for evaluating joint degeneration

Conclusions & Practical Application:

Emerging evidence suggests that information from the patient history and physical examination can help differentiate a variety of intra-articular hip conditions. Because there is substantial overlap among these conditions, further research is warranted to determine specificity and sensitivity of our clinical examination techniques. Preliminary evidence does indicate that these tests can be useful.

In cases where intra-articular hip pathology is suspected, the hip examination should always be accompanied by a screen of the lumbar spine, knee, and also the extra-articular structures of the hip and surrounding area.

By incorporating the tests reviewed above, manual medicine practitioners will have a better chance of correctly identifying these conditions, which will lead to more appropriate management.

Emerging evidence suggests that information from the patient history and physical examination can help differentiate a variety of intra-articular hip conditions.

Because there is substantial overlap among these conditions, further research is warranted to determine specificity and sensitivity of our clinical examination techniques. Preliminary evidence does indicate that these tests can be useful.