Acetabular Labral Tear (ALT)
Overview
Epidemiology
Up to 90% of patients with mechanical hip pain have acetabular labral tears1.
Etiology
Researchers have retrospectively attributed labral tears to a variety of causes. The most common theorized causes of acetabular labral tears are mechanical impingement and/or femoracetabular joint instability1. Other methods such as direct trauma, sports, and torsional or twisting hip movements have been attributed to acetabular labral tears1.
Although many potential mechanisms of injury have been cited, a large number of labral tears occur insidiously and are not associated with a specific event1.
Two common types of scenarios have been recognized:
- “A young person with a twisting injury to the hip, usually an external rotation force in a hyperextended position.”1
- “An older person with a history of hip and/or acetabular dysplasia, or the result of repeated pivoting and twisting.”1
There are a variety of etiologies of labral tears including degenerative, dysplastic, traumatic, or idiopathic1
- Degenerative etiologies are generally associated with inflammatory arthropathies1.
- Traumatic etiologies usually present with an immediate sharp pain along with mechanical symptoms (catching, locking, or clicking)1.
- Insidious etiologies have a dull type pain with intermittent sharp pain caused by particular movements (typically hip IR or ER)1.
Classification
Labral tears can be classified according to:
Type
Labral tears have been classified into four types:1
- Radial flap (the most common type)
- Radial fibrillated
- Longitudinal peripheral (least common)
- Abnormally mobile
Seldes’ Types
Alternatively, Seldes et al. created two classifications for acetabular labral tears based on the anatomical and histological features of the tear1.
Both type 1 and type 2 tears are “associated with chondrocyte proliferation and hyalinization of the labral fibrocartilage along the edges of the defect”1. Following a labral tear, the base of the tear adjacent to the attachment site is associated with increased microvascularity1. In addition, osteophyte formation is occassionally observed in labral tears1.
Type 1 Tears
Type 1 tears refer to an acetabular labral injury where the labrum is detached from the articular cartilage surface1. Typically, type 1 tears occur in the “transition zone” between the transition zone between the labrum and the articular hyaline cartilage1. They are perpendicular to the articular surface and, in some cases, extend to the subchondral bone1.
Type 2 Tears
Type 2 tears consist of one or more cleavage planes of variable depth within the substance of the labrum.251
Location
Acetabular labral tears have 3 main locations:
- Anterior
- Posterior
- Superior
It should be noted that anterior and anteriorsuperior acetabular tears are the most common1.
Anterior Tear
These tears are more common with degenerative hip diseases or acetabular dysplasia1. The anterior aspect of the labrum is subjected to higher forces and therefore greater stresses compared to the other aspects of the labrum, resulting in a higher prevalence of tears1. For example, the since the acetabulum and femoral head are oriented anteriorly, the femoroacetabular joint has the least bony constraint anteriorly and thus relies on the connective tissue of the joint capsule, acetabular labrum, and ligaments to maintain stability1.
History
Mechanical symptoms
A labral lesion causes a decrease in intraarticular joint pressure1 and an increase in joint laxity1. These two femoroacetabular joint changes result in a variety of mechanical symptoms:
Traumatic History
According to Dutton, acetabular labral tears may or may not include a history of trauma1. For those who have a history of trauma, the severity of the trauma to the femoroacetabular joint ranges from “very mild” to “severe”1. These femoroacetabular injuries generally involve a femoroacetabular joint stress combined with rotation1.
Pain history
Pain associated with acetabular labral tears can present in many different locations:
Pain can present in one area by itself or a combination of areas1
Pain onset can be acute and quick or gradual1.
The nature of the pain is generally “sharp” and associated with a clicking, snapping, catching or locking sensation1.
Aggravations
Movements that involve forced hip adduction with associated ER or IR generally aggravate this pain1.
Risk Factors
Prognosis
Diagnosis
Diagnosis of acetabular labral tear can generally be determined based on the the history and physical examination, regardless, the diagnosis is often delayed or is often misdiagnosed1. Delayed diagnosis or misdiagnosis if primarily due to the variable clinical presentations of labral tears1.
Physical Examination
“On examination, ROM of the hip may or may not be limited, but, in those cases where it is not limited, there may be pain at the extremes.25 There is little information regarding the sensitivity, specificity, or likelihood ratios associated with a single clinical test or a cluster of tests in diagnosing a labral tear.176 Generally speaking, the combined movement of flexion and rotation causes pain in the groin. More precisely, the specific maneuvers that may cause pain in the groin include”
Flex + ADD + IR
flexion, adduction, and internal rotation of the hip joint (impingement test/scour test) while it is held in at least 90 degrees of flexion and at least 15 degrees of abduction—positive with anterior—superior tears, anterior labral tears, and iliopsoas tendinopathy
Passive hEXT + ABD + ER
passive hyperextension, abduction, and external rotation (with posterior tears), with the patient lying supine at the edge of the table; a positive finding with this test is apprehension or exquisite pain and suggests anterior hip instability, an anterior labral tear, or posteroinferior impingement
Resisted SLR
resisted straight-leg raise test
Flex ER max ABD to Ext Abd IR
flexion of the hip with external rotation and full abduction, followed by extension, abduction, and internal rotation (anterior tears)
Ext ABD ER to Flex ADD IR
extension, abduction, and external rotation brought to a flexed, adducted, and internally rotated position (posterior tears).
Hip internal rotation with overpressure and the FABER test have been shown to demonstrate the highest sensitivity, compared to the resisted straight leg raise and scour test in identifying intra-articular hip pain.1791
Provocative tests
Signs & symptoms
- Strength deficits are not a consistent symptom of Acetabular labral tears1.
The following combination of symptoms are more reliable and increase the likelihood of a patient having an acetabular labral tear.
Diagnosis
Acetabular labreal tear diagnosis is primarily confirmed using MRA, MRI, and intra-articular anesthetic injections1.
“A diagnostic intra-articular hip injection was used as the gold standard to confirm the presence of intra-articular hip pathology (IAHP), as a positive diagnostic block has been shown to be 90% accurate in detection of hip internal derangement and a good predictor of improvement after surgical intervention”3
Management
Physical Therapy
Lewis and Sahrmann44 recommend the use of key elements of the examination to develop a plan of intervention (Table 19-18). Operative treatment has traditionally consisted of arthrotomy or arthroscopy with resection of the entire labrum or the portion of the labrum that is torn. Labral reconstruction is a newer technique that has gained popularity and has had good short-term results; however, the indications for this procedure are continuing to be refined.162
Post-operative POC
Postoperatively, the protocol can be divided into three phases174,180: Phase 1 (days 1–7): ▶ Weight bearing to tolerance with crutches. ▶ Isometric quadriceps, gluteal sets. ▶ AROM in all planes of motion. ▶ Closed-chain bridging, weight shifts, and balancing exercise. ▶ Open-chain standing abduction, adduction, flexion, and extension with no resistance. ▶ Avoidance of straight-leg raise exercises. Phase 2 (weeks 2–3): ▶ Progress off crutches and normalize gait. ▶ Progress ROM exercises to gradual end-range stretch within tolerance. ▶ Stationary bike, if tolerated. ▶ Open-chain above the knee-resistive Theraband or light pulley exercises. Phase 3 (weeks 4–6): ▶ Continue flexibility exercises. ▶ Progress resisted strengthening and closed-chain exercises. Emphasis is placed on hip and lumbopelvic stabilization, correction of hip muscular imbalance, and biomechanical control.181 ▶ Functional, and sport-specific functional, activities introduced as tolerated.1