An acetabular labrum tear or hip labrum tear is a common injury of the

acetabular labrum The acetabular labrum (glenoidal labrum of the hip joint or cotyloid ligament in older texts) is a fibrocartilaginous ring which surrounds the circumference of the acetabulum of the hip, deepening the acetabulum. The labrum is attached onto the bo ...

resulting from a number of causes including

running Running is a method of terrestrial locomotion by which humans and other animals move quickly on foot. Running is a gait with an aerial phase in which all feet are above the ground (though there are exceptions). This is in contrast to walkin ...

hip dislocation A hip dislocation is when the thighbone (femur) separates from the hip bone (pelvis). Specifically it is when the ball–shaped head of the femur (femoral head) separates from its cup–shaped socket in the hip bone, known as the acetabulum. Th ...

, and deterioration with

ageing Ageing (or aging in American English) is the process of becoming older until death. The term refers mainly to humans, many other animals, and fungi; whereas for example, bacteria, perennial plants and some simple animals are potentially biol ...

. Most are thought to result from a gradual tear due to repetitive

microtrauma Microtrauma is any of many possible small Injury, injuries to the body. Microtrauma can include the microtearing of muscle fibres, the sheath around the muscle and the connective tissue. It can also include stress to the tendons, and to the ...

. Acetabular labrum tears present with anterior hip or groin pain, and less commonly buttock pain. Frequently, there are also mechanical symptoms including clicking, locking, and giving way. Due to the limitations of the physical examination, further diagnosis still needs to be assessed by medical imaging. Studies have shown that there are some differences in the tear area of the acetabular labrum in different regions, which may be related to the differences in people's living habits. At present, there is not enough evidence to show that physical therapy is beneficial for the acetabular labrum. Conservative treatment is usually recommended initially, including relative rest, the use of anti-inflammatory and pain medications. Patients may also be considered for labral reconstruction surgery to help recover their athletic ability. In addition, since the cause of the acetabular labrum tear has not been proven to be directly related to any specific action, this condition is difficult to prevent.

Causes

It is estimated that 75% of acetabular labrum tears have an unknown cause. Tears of the labrum have been credited to a variety of causes such as excessive force,

, capsular hip hypermobility,

hip dysplasia Hip dysplasia is an abnormality of the hip joint where the socket portion does not fully cover the ball portion, resulting in an increased risk for joint dislocation. Hip dysplasia may occur at birth or develop in early life. Regardless, it doe ...

, and hip degeneration. A tight

iliopsoas The iliopsoas muscle (; ) refers to the joined psoas major and the iliacus muscles. The two muscles are separate in the abdomen, but usually merge in the thigh. They are usually given the common name ''iliopsoas''. The iliopsoas muscle joins t ...

tendon has also been attributed to labrum tears by causing compression or traction injuries that eventually lead to a labrum tear. Most labrum tears are thought to be from gradual tear due to repetitive

. Incidents of labrum tears increase with age, suggesting that they may also be caused by deterioration through the aging process. Labrum tears in athletes can occur from a single event or recurring trauma. Running can cause labrum tears due to the labrum being used more for weight bearing and taking excessive force while at the end-range motion of the leg: hyperabduction, hyperextension,

hyperflexion Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relativ ...

, excessive

external rotation Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relative ...

. Sporting activities are likely causes, specifically those that require frequent lateral rotation or pivoting on a loaded femur as in

hockey ''Hockey'' is a family of List of stick sports, stick sports where two opposing teams use hockey sticks to propel a ball or disk into a goal. There are many types of hockey, and the individual sports vary in rules, numbers of players, apparel, ...

ballet Ballet () is a type of performance dance that originated during the Italian Renaissance in the fifteenth century and later developed into a concert dance form in France and Russia. It has since become a widespread and highly technical form of ...

. Constant hip rotation places increased stress on the capsular tissue and damage to the

iliofemoral ligament The iliofemoral ligament is a thick and very tough triangular capsular ligament of the hip joint situated anterior to this joint. It attaches superiorly at the inferior portion of the anterior inferior iliac spine and adjacent portion of the marg ...

. This in turn causes hip rotational instability putting increased pressure on the labrum. Traumatic injuries are most commonly seen in athletes who participate in contact or high-impact sports like football, soccer, or golf. The prevalence rate for traumatic hip injuries that causes a tear of the labrum is very low. Less than 25% of all patients can relate a specific incident to their torn labrum; however, they are often a result of a dislocation or fracture. Falling on one's side causes a blunt trauma to the greater trochanter of the femur. Since there is very little soft tissue to diminish the force between the impact and the

greater trochanter The greater trochanter of the femur is a large, irregular, quadrilateral eminence and a part of the skeletal system. It is directed lateral and medially and slightly posterior. In the adult it is about 2–4 cm lower than the femoral head.Sta ...

, the entire blow is transferred to the surface of the hip joint. And since bone density does not reach its peak until the age of 30, hip traumas could result in a fracture. Tears of the hip labrum can be classified in a variety of ways, including

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines *Morphology (archaeology), study of the shapes or forms of artifacts *Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...

etiology Etiology (; alternatively spelled aetiology or ætiology) is the study of causation or origination. The word is derived from the Greek word ''()'', meaning "giving a reason for" (). More completely, etiology is the study of the causes, origins ...

, location, or severity. Anatomical modifications of the femur and or hip socket cause a slow buildup of damage to the cartilage. Femur or acetabular dysplasia can lead to femoral acetabular impingement (FAI). Impingement occurs when the femoral head rubs abnormally or lacks a full range of motion in the acetabular socket. There are three different forms of FAI. The first form is caused by a cam-deformity where extra bone is present on the

femoral head The femoral head (femur head or head of the femur) is the highest part of the thigh bone (femur The femur (; : femurs or femora ), or thigh bone is the only long bone, bone in the thigh — the region of the lower limb between the hip and the ...

, which leads to the head being non-spherical. The second deformity is referred to as a pincer deformity and it is due to an excess growth of the acetabular socket. The third type of FAI is a combination of the first two deformities. When either abnormality is present, it changes the position of the femoral head in the hip socket. The increased stresses that the femur and or acetabulum experience may lead to a fracture of the acetabular rim or a detachment of the overstressed labrum. External Rotation at the pelvic girdle

Diagnosis

An acetabular labrum tear is assessed by

physical examination In a physical examination, medical examination, clinical examination, or medical checkup, a medical practitioner examines a patient for any possible medical signs or symptoms of a Disease, medical condition. It generally consists of a series of ...

followed by

medical imaging Medical imaging is the technique and process of imaging the interior of a body for clinical analysis and medical intervention, as well as visual representation of the function of some organs or tissues (physiology). Medical imaging seeks to revea ...

. An MR

arthrogram An arthrogram is a series of images of a joint after injection of a contrast medium, usually done by fluoroscopy or MRI. The injection is normally done under a local anesthetic such as Novocain or lidocaine. The radiologist or radiographer perform ...

is more reliable than

magnetic resonance imaging Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to generate pictures of the anatomy and the physiological processes inside the body. MRI scanners use strong magnetic fields, magnetic field gradients, and ...

. A full confirmation can be made using

arthroscopy Arthroscopy (also called arthroscopic or keyhole surgery) is a minimally invasive surgical procedure on a joint in which an examination and sometimes treatment of damage is performed using an arthroscope, an endoscope that is inserted into the j ...

Epidemiology

In the United States acetabular labrum tears usually occur in the anterior or anterior-superior area, possibly due to a sudden change from labrum to acetabular cartilage. The most common labrum tears in Japan are in the posterior region, likely due to the customary practice of sitting on the floor. Posterior labrum tears in the Western world usually occur when a force drives the

posteriorly which transfers shear and compressive forces to the posterior labrum.

Rehabilitation

There is little evidence for the benefit of physical therapy for the acetabular labrum. Some studies though report that physical therapy could be of benefit in restoring "sports-ready" capabilities. Following surgery, such as labral reconstruction which has shown promising results in helping people by using an iliotibial band graft. Patients will use crutches for up to six weeks and physical exercise such as running, curtailed for at six months. There are usually four phases in the rehabilitation process: "Phase I: initial exercises (weeks 1–4), Phase II: intermediate exercises (weeks 5–7), Phase III: advanced exercises (weeks 8–12), and Phase IV: return to sports (weeks 12+)". Therapy programs need to be personalised. In phase I the first objective is to minimize pain and

inflammation Inflammation (from ) is part of the biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. The five cardinal signs are heat, pain, redness, swelling, and loss of function (Latin ''calor'', '' ...

. A symmetrical

gait Gait is the pattern of Motion (physics), movement of the limb (anatomy), limbs of animals, including Gait (human), humans, during Animal locomotion, locomotion over a solid substrate. Most animals use a variety of gaits, selecting gait based on s ...

pattern is essential so as not to create an imbalance in the muscles of the hip. Aquatic therapy enables more gravity-free movement. In phase II more flexibility in the soft tissue is promoted, with an emphasis on

strength training Strength training, also known as weight training or resistance training, is exercise designed to improve physical strength. It is often associated with the lifting of Weightlifting, weights. It can also incorporate techniques such as bodyweigh ...

basics. In phase III the focus is to begin building functional strength, using single leg exercises to build the muscle and challenge the strength of the hip. Phase IV is the final stage where further exercise is prescribed until returning to sports. Complex movements like

squatting Squatting is the action of occupying an abandoned or unoccupied area of land or a building (usually residential) that the squatter does not own, rent or otherwise have lawful permission to use. The United Nations estimated in 2003 that there wer ...

, kicking, and running, will be promoted until symmetrical pain free movements are achieved. File:Single Leg Bridge.jpg, Single leg bridge File:Side Leg Raise.jpg, Side leg raise File:Single Leg Balance.jpg, Single leg balance

Prevention

An acetabular labrum tear can occur in a variety of ways such as frequent twisting movement, direct trauma, or degeneration. But many hip labral tears are not directly related to any specific action, making it difficult to prevent such an injury. It may be possible to lower the risk by strengthening the gluteus, stretching before exercise, and discontinuing the use of repetitive twisting activities. One way to prevent a hip labrum tear is to decrease the pressure on the anterior labrum region. The labrum is about 2 to 3 mm thick but is wider and thinner in the anterior portion. Studies have found that in the United States and European countries, hip labral tears are commonly found in the anterior region. Muscular imbalance of the pelvis can develop ''lower crossed syndrome''. It is caused by tight

hip flexors In anatomy, flexor is a muscle that contracts to perform flexion (from the Latin verb ''flectere'', to bend), a movement that decreases the angle between the bones converging at a joint. For example, one's elbow joint flexes when one brings the ...

and

erector spinae The erector spinae ( ) or spinal erectors is a set of muscles that straighten and rotate the back. The spinal erectors work together with the glutes (gluteus maximus, gluteus medius and gluteus minimus) to maintain stable posture standing or si ...

with inhibited weak gluteals and

abdominals The abdomen (colloquially called the gut, belly, tummy, midriff, tucky, or stomach) is the front part of the torso between the thorax (chest) and pelvis in humans and in other vertebrates. The area occupied by the abdomen is called the abdominal ...

. Imbalance of the muscles can lead to an anterior pelvic tilt, increased hip flexion, and

lumbar hyperlordosis Lordosis is historically defined as an ''abnormal'' inward curvature of the lumbar spine. However, the terms ''lordosis'' and ''lordotic'' are also used to refer to the normal inward curvature of the lumbar and cervical regions of the human spi ...

of the lumbar spine. This increases the pressure in the anterior labrum. Weak gluteals during hip extension have also shown increased joint pressure in the anterior labrum. Muscles that help with balance need to be strengthened, or stretched to prevent a hip labrum tear. Exercises include strengthening the gluteus by abducting the hip whilst lying on the side with legs together. The top leg is raised keeping the knee and hip straight; especially effective where there is an anterior pelvic tilt. A tight hip flexor may be stretched by using a kneeling hip flexor stretch that targets the

. Stretching before exercise will affect the cartilage through "creep". It will place a constant load on the labrum, allowing fluid the leak out and deform to the applied load. This is significant for the

viscoelasticity In materials science and continuum mechanics, viscoelasticity is the property of materials that exhibit both viscous and elastic characteristics when undergoing deformation. Viscous materials, like water, resist both shear flow and strain lin ...

of the labrum. The hip labrum acts as a shock absorber, joint lubricator, stabilizer and pressure distributor. A warm-up using body weight squats can induce ''creep'' before exercise to help prevent a hip labrum tear. File:Acetabular Labrum Exercises.jpg, In A), Stretch of a right hip flexor, iliopsoas. The weight bearing knee (left) does not go past the toes. Leaning forward for a good stretch and holding it for about 15 to 20 seconds is needed. In B), The starting position for the side lying hip abduction. The top leg needs to be lifted straight up and repeated 10 times. File:Kniebeuge.jpg, A body weight squat with no added weights allows legs to be warmed up, creep may be induced in the cartilage and muscles to prepare for intense exercise. File:3StageCreep.svg, Strain vs. Time graph for the three stages of creep. Strain slowly rises up and almost becomes constant from a constant stress on a viscoelastic material. Like cartilage, it will deform or strain, from constant stress. The strain deformation is slow, but eventually too much stress will increase it.

References