Hip acetabular/labral tear
Anatomy of the hip joint showing the labrum around the acetabulum where the femoral inserts in the pelvis

Definition

Acetabular or hip labral tear (labral tear) refers to the rupture of the labrum, the cartilaginous rim that covers the acetabulum at the pelvis.

Labral tear illustrated in red

Pathology

The labrum is a critical structure of the hip joint as it stabilises the femoral head within the pelvic socket or acetabulum. One side of the labrum connects with the pelvis capsule and its ligaments and the other side with the head of the femur. This intra-articular side is poorly vascularised and difficult to heal after injury or surgery. 

A tear to the hip labrum mostly occurs with repetitive injury. It consists of a gradual process facilitated by a condition named femoral acetabular impingement, involving a reduced clearance between the femoral head and neck with the acetabulum. With repetitive internal rotation of the hip, the impinged labrum is subjected to increasing pressure, which over time leads to its rupture. In extreme cases this pressure can lead to the total avulsion of the labrum from the acetabulum.

Classification

Fractures of the humerus shaft can display various patterns: transverse, oblique, spiral, and comminuted. In addition they are differentiated depending on whether the fracture is displaced or undisplaced, relative to the loss of bone alignment and closed or open fracture. The AO (Arbeitsgemeinschaft für Osteosynthesefragen) Foundation, an international organisation founded in Switzerland, focussing on research and education for the management of orthopaedic injuries), is one of most used systems available to characterise humerus shaft fractures. According to the AO humerus shaft fractures are divided into their level of comminution:

Type A - No comminution

Type B - Presence of butterfly fragment (wedge-shaped fragment of bone

Type C - Comminution

Passive internal rotation movement of the hip
A labral tear can be caused by a CAM lesion, a Princer impingement or a combination of both

Causes

The aetiology of a hip labral tear is mostly unknown. The diagnosis is occasionally achieved without evident symptoms. The main causes include trauma and sport injuries. In sports the involvement of internal rotation of the hip with sudden changes of direction and twisting seem to be the origin of a labral tear of the hip. This pathology is also the consequence structural or congenital changes of the hip that weaken the joint stability. Known causes are:

Trauma (falls, motor vehicle accidents)

Sport injuries (golf, ice hockey, soccer, football, running, sprinting, ballet)

Capsular laxity (loose ligaments)

Cam lesion (bony protrusion) on the femoral head causing impingement

Pincer impingement: presence of extra bone (spur) at the rim of the acetabulum

Combination of CAM and Pincer

Hip dysplasia

Hip osteoarthritis in the elderly

Congenital hip dysplasia can lead to a hip labral tears later in life

Risk factors

A number of risk factors have been attributed to the development of hip labral tear:

Femoro-acetabular impingement

Congenital hip dysplasia

Capsular laxity

Hip joint degeneration (osteoarthritis)

Sports

Female gender

Ageing

Pain in the hip and groin area is typical in a hip labral tear

Symptoms

Although often asymptomatic, the symptoms of a hip labral tear include the following:

Pain to the groin area, buttock and anterior side of the hip

Pain increasing with movement

Pain with prolonged standing, sitting and walking

Pain becoming evident at rest

Noise e.g. clicking, locking, or catching of the hip with movement

Stiffness of the hip

Instability of the hip

Difficulty in walking, limp

Trendelenburg test is one approach to diagnosis of a hip labral tear

Diagnosis

The diagnosis of a hip labral tear is not always straightforward as its symptoms are similar to those of other hip pathologies. The clinical examination begins with the medical history to acquire information on injuries, life style, sport activities, or previous diagnosis of hip structural deficiencies that may increase the risk of a labral tear of the hip. The examiner will assess any changes in the range of movement of the hip, its stiffness, muscle discrepancy and gait abnormalities such as a limp. 

A positive Trendelenburg test is a sign of the pathology whereby the hip with a labral tear drops when standing on the opposite leg.  Another tests is the impingement sign, consisting of flexing the hip to 90º, turning the hip inward with internal rotation and bringing the thigh towards the opposite hip (adduction). 

X-rays are taken to establish possible structural abnormalities in the hip joint and MRI scans to detect changes of the labrum itself, tendons, ligaments and capsule. A specific MRI named magnetic resonance arthrography (MRA) is more accurate as it improves the image quality following local injection of the contrast agent gadolinium. 

Treatment

Anti-inflammatory therapy reduces inflammation and pain acutely after a hip labral injury

Nonoperative treatment

Conservative treatment is considered more relevant today than before when surgical removal of the labrum was performed leaving the hip unsupported. 

The nonoperative approach is mostly based on physical therapy to reinforce the muscles around the hip and modify posture, movement and alignment assessed with precise gait analysis. Acutely, iIt is advised to minimise weight bearing with the use crutches. The movement of the hip can be corrected with the use of a SERF strap (Stability through External Rotation of the Femur) that is applied around the thigh, knee, and lower leg to support the hip during movement by keeping it into external rotation. Additional conservative treatment includes:

Rest

Pain management with analgesics

Anti-inflammatory drugs (NSAIDs)

Local steroid injection

Example of arthroscopic surgery used to repair the ruptured labrum
Drawing of a labral refixation

Surgical treatment

With more severe damage to the hip labrum or failure of conservative therapy, surgery is recommended. The surgical approach mostly relies on hip arthroscopy, which is used also as a diagnostic tool. The purpose of hip arthroscopy is multi-fold:

Labral refixation used to reattach the disconnected labrum to the edges of the acetabulum using suture and screws

Debridement of the labrum; when greater damage of the labrum occurs and cannot be salvaged, part of the cartilage is debrided (removed) to avoid that it interferes with the movement of the hip causing pain.

When severe hipbone abnormalities are present or in case of femoro-acetabular impingement, open hip surgery becomes necessary to resolve the complexity of the pathology.

Reducing weight bearing alleviates pain and speeds recovery after a hip labral injury

Rehabilitation

Physical therapy is indicated following a short period of rest and guided by a physiotherapist. With a successful conservative treatment for minor labral tears the prognosis is up to 6 weeks whereas following surgery for more severe labral tears up to 8 weeks or longer.

The intensity of physical exercise is increased in accordance with the improvement of symptoms. The aim of physiotherapy is to improve joint flexibility and strengthening the pelvis, glutei and thigh muscles to stabilise the hip. Physiotherapy management also includes:

Rest

Ice treatment

Antiinflammatory therapy (NSAIDs)

Use of crutches

Exercise in the pool to reduce stress on hips

Stretching

Walking

Climbing stairs

Activity modifying regime

Return to activity plan

Strengthening the muscles around the hips and buttocks reduces the risk of injuries to the labrum

Prevention

The most effective prevention for a labral tear of the hip involves the modification of activities during strenuous sport that increase the risk of the pathology. In such activities it is recommended to keep the entire musculature around the hip well toned and flexible. It is important to avoid loading the hip with full body weight especially when the legs are at maximal aperture from the normal range of the hip.