The acetabular labrum (glenoidal labrum of the hip joint or cotyloid ligament in older texts) is a ring of
cartilage
Cartilage is a resilient and smooth type of connective tissue. In tetrapods, it covers and protects the ends of long bones at the joints as articular cartilage, and is a structural component of many body parts including the rib cage, the neck an ...
that surrounds the
acetabulum
The acetabulum (), also called the cotyloid cavity, is a concave surface of the pelvis. The head of the femur meets with the pelvis at the acetabulum, forming the hip joint.
Structure
There are three bones of the ''os coxae'' (hip bone) that c ...
of the hip. The anterior portion is most vulnerable when the labrum tears.
It provides an articulating surface for the
acetabulum
The acetabulum (), also called the cotyloid cavity, is a concave surface of the pelvis. The head of the femur meets with the pelvis at the acetabulum, forming the hip joint.
Structure
There are three bones of the ''os coxae'' (hip bone) that c ...
, allowing the head of the
femur
The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates with ...
to articulate with the pelvis.
Acetabular labrum tear
Mechanisms of Injury
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, ]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 ...
, 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 (; from lat, ile, lit=groin and grc, ψόᾱ, psóā, muscles of the loins) 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 usu ...
tendon has also been attributed to labrum tears by causing compression or traction injuries that eventually lead to a labrum tear.[Smith, M., Panchal, H., Ruberte, R., & Sekiya, J. (2011). Effect of acetabular labrum tears on hip stability and labral strain in a joint compression model. The American Journal of Sports Medicine, 39, 103S-110S.] Most labrum tears are thought to be from gradual tear due to repetitive microtrauma
Microtrauma is any of many possible small 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 bones (see ...
.[ 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.][Rylander, L., Froelich, J., Novicoff, W., & Saleh, K. (2010). Femoroacetabular impingement and acetabular labral tears. Orthopedics, 33(5), 342-350] Running can cause labrum tears due to the labrum being used more for weight bearing and taking excessive forces 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 relative ...
, 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 relativ ...
.[ Sporting activities are likely causes, specifically those that require frequent lateral rotation or pivoting on a loaded femur as in ]hockey
Hockey is a term used to denote a family of various types of both summer and winter team sports which originated on either an outdoor field, sheet of ice, or dry floor such as in a gymnasium. While these sports vary in specific rules, numbers o ...
or 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 ligament of the hip joint which extends from the ilium to the femur in front of the joint. It is also referred to as the Y-ligament (see below). the ligament of Bigelow, the ligament of Bertin and any combinations ...
. 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.][Groh, Megan M., and Joseph Herrera. "A Comprehensive Review of Hip Labral Tears." Curr Rev Musculoskeletal Med. 2.2 (2009): 105-117. Web. 16 Oct. 2013] 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.Stan ...
, the entire blow is transferred to the surface of the hip joint.[Byrd, J.W. Thomas. "Lateral Impact Injury." Clinics In Sports Medicine. 20.4 (2001): 801-815. Web. 16 Oct. 2013] 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 (pronounced ; alternatively: aetiology or ætiology) is the study of causation or origination. The word is derived from the Greek (''aitiología'') "giving a reason for" (, ''aitía'', "cause"); and ('' -logía''). More completely, e ...
, 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).][Rahman, Abdel, Sathish Rajasekaran, and Haron Obaid. "MRI Morphometric Hip Comparison Analysis of Anterior Acetabular Labral Tears." Skeletal Radiol. (2013): 1246-1252. Web. 17 Oct. 2013] 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). It is supported by the femoral neck.
Structure
The head is globular and forms rather more than a hemisphere, is directed upward, medialward, and a l ...
, 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 that the femoral head occupies 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.][
]
Diagnosis
A acetabular labrum tear is assessed by physical examination
In a physical examination, medical examination, or clinical examination, a medical practitioner examines a patient for any possible medical signs or symptoms of a medical condition. It generally consists of a series of questions about the patien ...
followed by medical imaging. 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 form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio wave ...
. A full confirmation can be done by 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 ...
.
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 ]femoral head
The femoral head (femur head or head of the femur) is the highest part of the thigh bone (femur). It is supported by the femoral neck.
Structure
The head is globular and forms rather more than a hemisphere, is directed upward, medialward, and a l ...
posteriorly which transfers shear and compressive forces to the posterior labrum.[
]
Rehabilitation
With physical therapy, there is only a small amount of evidence on rehabilitation techniques for the acetabular labrum.[Garrison, Craig J., Osler, Michael T., Singleton, Steven B. (2007). "Rehabilitation after Arthroscopy of an Acetabular Labral Tear". ''North American Journal of Sports Physical Therapy''. 2(4), 241–250.] It is even thought that physical therapy could be controversial due to there not being any evidence of a specific effective therapy routine.[
There are, however, some studies that report physical therapy could benefit the patient by bringing them back to “sports-ready” capabilities.][Lewis, Cara L. & Sahrmann, Shirley A. (2006). "Acetabular Labral Tears". ''Journal of the American Physical Therapy Association''. 86, 110–121.] It is advised that physical therapists keep up on the new findings and stay in close contact with the orthopaedic surgeon
Orthopedic surgery or orthopedics ( alternatively spelt orthopaedics), is the branch of surgery concerned with conditions involving the musculoskeletal system. Orthopedic surgeons use both surgical and nonsurgical means to treat musculoskeletal ...
so they have the best idea of how to approach their patient's case.[ Following surgery, crutches will be used for up to six weeks and there should be no expectation to return to activities such as running for at least a period of six months.
Some things to note when rehabilitation occurs is that it is important to know the size and placement of the tear. There are usually four phases in the rehabilitation process noted as: "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+)".][
All physical therapy regimens should be individualized from person to person based on all adequate criteria
In phase I of the rehabilitation process the first objective is to minimize the pain and ]inflammation
Inflammation (from la, wikt:en:inflammatio#Latin, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or Irritation, irritants, and is a protective response involving im ...
. It is important to begin conducting small motion exercises that have up to 50% weight bearing capacity by the patient. A symmetrical gait pattern is imperative as not to create an imbalance in the muscles of the hip. Aquatic therapy is highly encouraged and looked upon due to its ability to help the patient move more freely without the pressure of gravity. To progress to phase II of the rehabilitation process patients should be able to complete straight leg raises while lying on their side to strengthen the sartorius and tensor fasciate latae muscles to build support in the leg.
In phase II the physical therapist should be trying to promote more flexibility in the soft tissue. There should be more emphasis on the beginning aspects of strength training
Strength training or resistance training involves the performance of physical exercises that are designed to improve strength and endurance. It is often associated with the lifting of weights. It can also incorporate a variety of training te ...
while adding some resistance over time. In order to progress to phase III, the patient should be able to demonstrate a normal gait pattern and minimal pain with exercises like the single leg bridging to help strengthen the hamstring muscles to help with leg equality.
In phase III the focus is to begin building functional strength. Movements should include single leg exercises to build the muscle and challenge the strength of the hip.
In order to progress to phase IV the flexibility of the patient should be adequate. Phase IV is the final stage in which the physical therapist would assess and prescribe any further exercise up until the patient is ready to return to the sport.[ Usually the therapist would start using 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 ...
, kicking, and running. The therapist would look for symmetrical movements on both sides of the body without pain. If the patient demonstrates the symmetrical movements without pain, the physical therapist would use their discretion for the patient's clearance. Some things to avoid from while rehabilitating are sitting with "knees lower than the hips, legs crossed where hip is rotated, and sitting on the edge of the seat and contracting the hip flexor muscles."[
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
Hip labrum tear can occur in a variety of ways such as frequent twisting movement,
direct trauma, or degeneration.[ Despite the many different possibilities, a large percentage
of hip labral tears are not directly related to any specific action,][ making it difficult to
prevent such an injury. But it may be possible to lower the risk by strengthening the ]gluteus
The gluteal muscles, often called glutes are a group of three muscles which make up the gluteal region commonly known as the buttocks: the gluteus maximus, gluteus medius and gluteus minimus. The three muscles originate from the ilium and s ...
,
stretching before exercise, and discontinued use of repetitive twisting activities.
One way to prevent a hip labrum tear is to decrease the pressure on the anterior 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
A flexor is a muscle that flexes a joint. In anatomy, flexion (from the Latin verb ''flectere'', to bend) is a joint movement that decreases the angle between the bones that converge at the joint. For example, one’s elbow joint flexes when one ...
and erector spinae with inhibited weak gluteals and
abdominals
The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the torso. ...
.[ 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 spin ...
of the lumbar spine. This increases the pressure in the anterior
labrum.[ Weak gluteals during hip extension has also shown increased joint pressure in the
anterior labrum. To prevent a hip labrum tear, you will have to strengthen muscles or
stretch tight muscles that might cause any muscular imbalance. A great exercise to strengthen
the gluteus is the side lying hip abduction. You will be lying on your side with your legs on top of each other. You will raise the top leg up while keeping the knee and hip straight. This exercise
targets the gluteus medius and is effective especially in those with an anterior pelvic tilt.][ To stretch a tight hip flexor, you can do the kneeling hip flexor stretch that targets
the iliopsoas. These exercises are a great way to strengthen and stabilize the pelvis
and hip joint to prevent a hip labrum tear.
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 shear flow and strain linearly wi ...
of the labrum.[AF, Mark."The apparent viscoelastic behavior of articular cartilage-- the
contributions from the intrinsic matrix viscoelasticity and interstitial fluid flows." J
Biomech Eng. 1986 May;108(2):123-30.] The hip labrum acts as a shock absorber, joint
lubricator, stabilizer and pressure distributor.[ With this essential warm up, it is possible for it
to be better prepared to prevent a hip labrum tear. Body weight squats are a great example of
stretching and warming up the body to induce creep before exercise.
File:Acetabular Labrum Exercises.jpg, In A), Stretch of a right hip flexor, iliopsoas. Make sure your weight bearing knee (left) does not go past your toes. You will want to lean forward for a good stretch and hold it for about 15 to 20 seconds. In B), this will be your starting position for the side lying hip abduction. You will want to be in a comfortable position. Slowly lift the top leg (right) straight up. Perform one set of 10 repetitions.
File:Kniebeuge.jpg, This man is doing a body weight squat. There are no added weights to his body, allowing him to warm up his legs properly. This is a great way to induce "creep" 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 your cartilage, it will deform or strain, from constant stress. The strain deformation is slow, but eventually too much stress will increase it.
]
See also
*Glenoid labrum
The glenoid labrum (glenoid ligament) is a fibrocartilaginous structure (not a fibrocartilage as previously thought) rim attached around the margin of the glenoid cavity in the shoulder blade. The shoulder joint is considered a ball and socket ...
References
{{DEFAULTSORT:Acetabular Labrum
Ligaments of the lower limb