There are two types of cartilage in the hip. One is the surface cartilage, and the other is the labral cartilage. The labral cartilage actually runs along the rim of the socket. The labrum has been known for quite some time as a piece of anatomy, but also is a source of pain when torn.
http://www.wakehealth.edu/Orthopaedic-Services/Hips/Labral-Tears-FAQ.htm
The term labrum is used in anatomy to designate a lip, edge, or brim. Plural: labra. The glenoid labrum is a ring of fibrocartilage that runs around the cavity of the scapula (wingbone) in which the head of the humerus (the bone in the upper arm) fits. The labrum deepens this cavity (the glenoid cavity) and effectively increases the surface of the shoulder joint.
http://www.medicinenet.com/script/main/art.asp?articlekey=18656
A hip (acetabular) labral tear is damage to cartilage and tissue in the hip socket. In some cases, it causes no symptoms. In others it causes pain in the groin. It can make you feel like your leg is catching or clicking in the socket as you move it. Over time, labral tears in the hip may cause permanent damage to the joint. The labrum is a band of tough cartilage and connective tissue that lines the rim of the hip socket, or acetabulum. It cushions the joint of the hip bone, preventing the bones from directly rubbing against each other. The labrum also helps keep the leg bone in place and increases stability of the joint.
http://www.webmd.com/a-to-z-guides/acetabular-labral-tear-the-basics
The acetabular labrum is a ring of fibrocartilage that runs around the acetabulum (cup) of the hip joint and increases its depth. The causes of injury to the acetabular labrum, the signs and symptoms, and treatment are like those for a glenoid labrum injury. Labrum was borrowed from the Latin for lip.
http://www.medicinenet.com/script/main/art.asp?articlekey=18656
The labrum of the hip is a thickened cartilage ring that lines the outer rim of the hip acetabulum (socket). The labrum functions to increase contact area in the hip and to maintain a fluid seal within the joint. Arthroscopic probing of an obvious labral tear of the hip. The labrum also contains nerve fibers and tears can result in pain and mechanical symptoms. Tears of the labrum can occur for many reasons. Common causes can include trauma, repetitive activities, femoroacetabular impingement, and early degenerative change.
http://www.drmichaelwind.com/hip-surgery/labral-tears-of-the-hip/
The primary goal of labral tear recovery is to safely enter the hip joint, identify what is the suspected problem, which often involves the labral cartilage tearing, and then to repair the anatomy. At the same time, in addition to restoring the anatomy, surgeons try to remove any bad mechanics of the hip.
http://www.wakehealth.edu/Orthopaedic-Services/Hips/Labral-Tears-FAQ.htm
The labrum is a deep cartilage structure, so being located around the hip joint, a labral tear can be confused with many other potential sources of pain. Common symptoms include back problems, disc problems, occasionally intra-pelvic problems – ovarian type pain symptoms.
http://www.wakehealth.edu/Orthopaedic-Services/Hips/Labral-Tears-FAQ.htm
Symptoms. Patients with tears of the hip labrum often will have pain deep within the groin or lateral aspect of the hip. The pain is usually quite deep and can not be “massaged” or “stretched”. Patients can not put their hand on the pain but there is obviously something wrong.
http://www.drmichaelwind.com/hip-surgery/labral-tears-of-the-hip/
The labrum can tear for many reasons. Some people get a torn labrum from falls or car accidents. Sports that require regular rotation of the hip -- like golf, soccer, hockey, and ballet -- increase the risk. So do running and sprinting. But almost 75% cases of torn acetabular labrum have no known direct cause.
http://www.webmd.com/a-to-z-guides/acetabular-labral-tear-the-basics
The acetabular labrum (glenoidal labrum of the hip joint or cotyloid ligament in older texts) is a ring of cartilage that surrounds the acetabulum of the hip. The anterior portion is most vulnerable when the labrum tears.
https://en.wikipedia.org/wiki/Acetabular_labrum
what is the labrum in the hip
The labrum of the hip is a thickened cartilage ring that lines the outer rim of the hip acetabulum or socket. The labrum of the hip is a thickened cartilage ring that lines the outer rim of the hip acetabulum  or socket.