WHAT IS THE HIP LABRUM?
- The hip is a ball-and-socket joint, and the hip labrum is a fibrocartilaginous structure that lines the hip joint.
- The labrum functions as a shock absorber, joint lubricator and distributes pressure across the joint (Groh and Herrera, 2009).
- The labrum deepens the joint and decreases contact stress on the hip joint.
- The labrum also creates a seal to pressurize the joint and the synovial fluid prevents direct contact between the two bones (femoral head and acetabular cartilage).
- Without the labrum, the articular cartilage is subject to increased pressure and can lead to early joint deterioration. In studies, contact stress increased by 92% without the labrum (Hunt et al, 2007; Ferguson et al, 2000).
- A tear in the labrum would could destabilize the hip joint and acetabular labral tears may lead to early onset hip osteoarthritis (Groh and Herrera, 2009). Learn more about hip osteoarthritis here.
WHAT IS A HIP LABRAL TEAR?
- Labral tears can occur from an acute injury or "wear-and-tear." In some cases, labral tears may simply represent the natural history of the joint with age. In cadaveric studies, labral tears and abnormalities were found in 93–96% of hips (Groh and Herrera, 2009).
- Anatomical variations, including joint capsule laxity or hypermobility of the hip joint, hip dysplasia and femoral acetabular impingement can cause damage of the labrum.
- Chondral injuries are the most common injury associated with labral tears, including thinning of the cartilage, delamination of the cartilage, chondral flap tears and full-thickness chondral injuries with exposed bone (Bharam, 2006).
WHAT IS HIP IMPINGEMENT OR FAI?
- Femoral-acetabular impingement is cause by extra bone around the hip joint that can cause pinching of the labrum between the femur and acetabulum of the hip joint. With time the labrum can become damaged, most often effecting the anterosuperior acetabular cartilage separating the labrum from the cartilage.
HOW DO YOU KNOW IF YOU HAVE A HIP LABRAL TEAR?
- Labral tears typically cause pain, with more than 90% of patients diagnosed with acetabular labral tears complaining of anterior hip and groin pain (Groh and Herrera, 2009). In some cases, pain can refer to the thigh or the lateral and posterior hip region (Hunt et al, 2007; Burnett et al, 2006). This may be due to the location of the tear, with anterior hip or groin pain more consistent with an anterior labral tear and buttock pain more consistent with a posterior labral tear (Hase & Ueo, 1999).
This pain is generally a constant dull ache with occasional sharp pains with certain positions. In some cases patients may also experience clicking, catching, or locking in their hip or a sensation of the leg giving way (Groh and Herrera, 2009).
In many cases the pain starts insidiously without a specific injury or cause (Groh and Herrera, 2009). Symptoms are often aggravated by walking, pivoting, prolonged sitting, and with impact activities, such as running.
In over 70% of cases, the pain worsens at night (Hunt et al, 2007).
HOW IS A HIP LABRAL TEAR DIAGNOSED?
Diagnosis is based on detailed history, physical examination, and imaging, but unfortunately, the diagnosis is often delayed and on average patients wait greater than 2 years before a diagnosis and often have to see multiple health care providers (Groh and Herrera, 2009).
The patient will be put through various repetitive movements testing the hip, looking for symptom exacerbation. Certain physical tests may be utilized to reproduce symptoms at time of exam.
Diagnostic imaging usually begins with x-rays to look for structural abnormalities in the hip and pelvis, including findings of femoral-acetabular impingement and associated arthritis.
Magnetic resonance imaging (MRI) and magnetic resonance arthrography (MRA) are often utilized to diagnose labral pathology. MRA historically have had a higher sensitivity and accuracy due to the contrast dye injected into the joint, as the dye distends the joint capsule and outlines the labrum with contrast filling any tears (Su et al, 2019), but perilabral sulci or recesses can result in false positives. Newer 3.0 T conventional MRIs appear to be superior to MRAs in detecting acetabular labral tears (Zhang et al, 2022).
HOW ARE HIP LABRAL TEARS TREATED?
Conservative Management
- Initial treatment often consists of rest, NSAIDs, activity modification and physical therapy. The hip labrum is mostly avascular with the blood supply only penetrating the outer 1/2, complicating the labrum's ability to heal on its own, and in many cases the pain recurs when returning to the prior level of activities (Lewis and Sahrmann, 2006).
Intra-articular Injections
- Anesthetic injections can be diagnostic and help determine whether the pain is coming from inside the hip joint or other extra-articular pathology outside the joint.
- Corticosteroid injections may also be utilized for diagnostic reasons to help determine whether the pain is coming from inside the hip joint or other extra-articular pathology. In younger patients, there is some concern that intra-articular steroids may damage the cartilage (Hunt et al, 2007).
- Platelet rich plasma (PRP) has been studied in a case series of patients with evidence of a labral tear on MRI/MRA. In this pilot study by De Luigi et al. eight patients had a statistically significant functional improvements and decreased pain at 2, 6, and 8 weeks post-injection, suggesting that PRP may provided short-term pain relief and functional improvement up to 8-week after the procedure (De Luigi et al, 2019).
