Assessing and managing acetabular labral tears

England’s Ruben Loftus-Cheek holds his hip, 2017

Mechanical disruption of the hip joint is often related to an acetabular labral tear (ALT) and can be associated with intraarticular snapping hip syndrome in up to 80% of cases^(1). Labral tears affecting the hip joint are prevalent in 22-55% of patients with hip or groin pain and evidence suggests that an untreated ALT may predispose an individual to early degenerative hip arthritis, which has created a widespread interest within clinical practice and the literature^(2,3).

The examination and imaging techniques with suspected ALT’s have increased greatly in the past decade, but an assessment of a labral tear still remains complex. The purpose of this article therefore is to review the anatomy and biomechanics of the acetabular labrum, the examination techniques and the treatment and management options available.

Anatomy and biomechanics

The labrum increases the surface area of the acetabulum by 22% and the volume by 33% and it functions by forming a seal for the head of femur to rotate in (see figure 1). From a cross-sectional view, the labrum is triangular in its appearance with the extra articular zone being dense connective tissue that has a rich blood supply and the intra articular zone largely having no blood supply⁽³⁾.

At the extreme end ranges of hip motion, the labrum is stressed by compressive forces -a tear at this point can affect joint stability and load distribution⁽²⁾. Furthermore, pain receptors have been located in the superior and anterior areas, and the labrum is therefore considered to be a pain-generating structure⁽⁴). It is at the anterior surface where an ALT is most at risk due to the compressive forces at the end point of hip flexion (see figure 1)⁽⁵⁾. Also of note is that structural abnormalities such as retroverted acetabulum and coxa valga have been observed concurrently in patients (87%) with labral tears⁽⁶⁾.

Figure 1: illustration of an acetabular labral tear at the anterior surface

Examination and assessment

An ALT is complex to diagnose and despite recent advances in medical imaging and assessment techniques, one report identified that on average, patients visited three healthcare providers and also waited for 21 months before an ALT was correctly diagnosed⁽³⁾. When examining a patient with a suspected ALT, clinicians should also consider femoro-acetabular impingement (FAI) and acetabular cartilage damage, and MRI imaging should be used to support the clinical findings⁽³⁾.

Acetabular labral tears are often the result of cutting, pivoting, twisting as well as repetitive movements into end range hip flexion commonly found in tennis players, footballers and runners. This might help explain why researchers from the New England Baptist hospital in Boston, USA found that from 436 arthroscopies of labral tears in athletes, 273 (62%) also had articular cartilage damage⁽⁶⁾. However the exact mechanism of an ALT injury may not always be apparent to the patient, as it may be degenerative, congenital or traumatic in its occurrence⁽²⁾.

During a physical assessment of a hip related injury it is essential to be vigilant for a non-musculoskeletal related pathology. Hip related pain may be associated to an ALT but may also be the result of lumbar spine or pelvic girdle dysfunction, abdominal viscera and the peripheral nervous system⁽²⁾. Pain at rest, night pain, fever, night sweats, and generally feeling unwell and unexplained weight loss are indicators of a non musculoskeletal pathology and require referral for further examination by a healthcare provider⁽²⁾. Reiman and colleagues also indicated that hip pain may be related to the abdominal and pelvic organs and a musculoskeletal injury must not be assumed⁽²⁾.

A patient with an undiagnosed ALT may also present with synovitis and joint inflammation and may adopt positions of hip flexion, external rotation and slight abduction, which place the capsule at its largest potential volume to reduce the stress on the labrum. Positions which include flexion and or adduction have been found to increase the overall load on the labrum and this are consciously avoided.

The combined impingement position of flexion, adduction and internal rotation, known as ‘FADDIRs test’ increases stress to the labrum, but is also a contributor to intra-articular hip pathology⁽⁷⁾. Patients with an ALT may also complain of pain on squatting, stepping up with the involved limb, or sitting in a chair with the hips positioned lower than the knees. In addition a patient with an ALT is unlikely to extend fully at the hip during gait as this places the greatest load to the anterior joint capsule and consequently stress to the anterior labrum (see table 1).

Table 1: Specific tests for acetabular labral tear

Surgical versus non-surgical treatment

Hip arthroscopy is a widely used treatment adjunct in patients presenting with an ALT symptomatic of longer than four weeks and confirmed by MRI (magnetic resonance imaging) or MRA (magnetic resonance arthrogram)⁽⁴⁾. Hip athroscopy for an ALT may include either labral debridement or labral repair. In contrast to surgical repair there is limited support for conservative treatments for an ALT. However researchers from Sao Paulo, Brazil have provided a case series of four patients that underwent a rehabilitation programme for an ALT without surgery⁽⁸⁾.

The four patients were diagnosed by an MRI scan and underwent a 3-phase programme with the first being pain control, trunk and hip stabilisation, re-education and correction of abnormal joint movement. Phase two focused on restoring normal range of motion, muscular strength and commencing sensory motor training. The final phase of their rehabilitation programme focused on preparing the athlete for a return to sport. The four patients involved in the case series were in their mid twenties and were from both sedentary and athlet ic backgrounds⁽⁸⁾. The results of the conservative rehabilitation programme yielded a decrease in pain levels, functional improvement and correction of muscle imbalances. Increased muscle strength was noted with the hip flexors increasing from 1% to 39%, hip abductors increasing from 18% to 56% and the hip extensors increasing from 68% to 139%. The strength of this research is limited, with the case series being just four patients but nevertheless could provide a very good proactive approach whilst a patient is awaiting an arthroscopy.

Table 2: Suggested exercises to include during weeks 1-4 post surgical intervention

Rehabilitation

Rehabilitation following surgical repair of an ALT is limited in terms of its evidence, both within the surgeons own rehabilitation protocol and the therapist’s expertise. 

Phase 1 (weeks 1–4)

• Following labral debridement, weight bearing should be limited to 50% partial weight bearing for 7-10 days, with flexion limited to 90° for 14 days. A labral debridement also has no limits postoperatively into abduction, internal or external rotation or extension. In contrast a labral repair should maintain non-weight bearing or toe-touch weight bearing for three to six weeks post operatively.
• The ranges of movement should be far more conservative in labral repair, while internal and external rotation should be conservatively moved into for 3 weeks. Do note that if other procedures are carried out such as microfracture repair then the post-op protocol may well be different.
• During the immediate post-operative period, it is essential to manage pain, reduce swelling and initiate early movement at the affected limb, but it is also essential to focus on other factors such as core activation and abductor control (see table 2). A strong association exists between decreased activity of the hip abductor muscles and lower kinetic chain injuries, including anterior knee pain⁽⁹⁾. Therefore, once the hip ranges are accessible, it is essential to encourage a patient to activate the deep hip and trunk stability muscles to prevent secondary injuries from occurring.

Phase 2 (weeks 5–7)

• During this stage of rehabilitation it is essential to restore normal range of movement with an emphasis on increasing strength and developing flexibility of the muscles crossing the hip joint.

Exercises to include during weeks 5-7

• Cycling with increased resistance
  
  

• Crosstrainer

Phase 3 (weeks 8-12)

• This phase is a great opportunity to develop cardiovascular fitness and functional control of the hip. Functional stability exercises should be carried out in a standing position with an emphasis on maintaining and improving stability ready for sporting participation. Exercises to include in this phase are walking lunges, lunges with trunk rotation over the front leg and a Swiss ball programme appropriate for challenging the core muscles. Garrison and colleagues have provided criteria (see table 3) to follow ready for progression to phase four which is preparation for return to sport⁽¹⁰⁾.

Phase 4 (weeks 12+)

• This phase of the rehabilitation programme is the time to be preparing the athlete for their return to sport, and particularly their position it has specific tasks. If the athlete is a defender in football, they should be replicating tasks specific to their position. Prior to the patient resuming full training, they must be able to demonstrate the same neuromuscular control as the uninvolved side.

Table 3: Training for fitness and functional control of hip

Summary

A suspected ALT using the history and clinical texts should be confirmed using an MRI or MRA to confirm the presence of an ALT but also to exclude any referred pain masquerading as a musculoskeletal injury. An appropriate rehabilitation programme should be started immediately to improve hip and trunk control and to manage pain. This will allow the patient to proceed through the surgery with greater ease having already commenced a rehabilitation programme.