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Exploring Hip Pain: Femoroacetabular Impingement

Hip pain. Clients of all shapes, sizes and ages complain about it. Hip issues can be as simple or as complex as each individual, and a good personal trainer knows how to assess for mobility and function and when to refer out to a physician or physical therapist. Recently there has been a lot of buzz in physical therapy and sports medicine circles about a “new” dysfunction of the hip called femoroacetabular impingement (FAI).

FAI is a pathomechanical process in which abnormal contact stresses between the ball and socket cause joint damage around the hip, predisposing the client to osteoarthritis and labral degeneration (Leunig, Beaulé & Ganz 2009). FAI-related pain may be felt in the groin, in the lower back, around the hip and sometimes in the thigh. How do personal trainers properly assess this dysfunction in clients and know when to take certain measures? What type of programming is recommended when a doctor prescribes conservative treatment? This article answers these questions and more and includes a review of FAI, its clinical presentation and its pathology, as well as information about medical and physical therapy treatment approaches.

What Is FemoroAcetabular Impingement?

FAI is a culprit for early “primary” osteoarthritis of the hip, especially in young and active clients (Tannast, Siebenrock & Anderson 2007). Characterized by “an early pathologic contact” between acetabulum prominences and the femur during hip movement, FAI limits the hip’s range of motion (ROM). This is seen mainly in flexion and internal rotation (Emara et al. 2011; Crawford & Villar 2005). FAI is frequently aggravated by athletic activities and movements that require excessive hip flexion, by prolonged walking, by pivoting on the affected side or by prolonged sitting or driving. Common symptoms include a localized, deep ache in the groin and in the front of the hip. Occasionally, pain refers to the outside of the hip, buttocks and thigh area. If there is a labral tear, mechanical symptoms such as painful locking or “giving way” are common (Hossain & Andrew 2008).

There are many theories as to how and why an individual develops FAI. One theory is that during development, structural abnormalities of the hip—such as hip dysplasia (femur dislocation)—occur (Pollard 2011). Other causes include physical stresses or trauma such as a femoral neck fracture. This type of fracture is commonly seen in active, middle-aged adults—specifically males who play hockey, tennis or soccer (Byrd & Jones 2011). Genetics is another potential factor (Leunig, Beaulé & Ganz 2009). In all cases, one thing is certain: FAI occurs when there is an abnormality of the femoral head and its congruency to the acetabulum.

FAI can develop over time. Repeated and excessive hip flexion and internal rotation place maximal contact between the anterosuperior femoral head–neck junction and the acetabular labrum, especially when there is not enough clearance to avoid friction. The repetitive movement and compressive load create a torsion effect on the internal structures inside the hip socket (Emara et al. 2011). A person who has FAI that has progressed will develop an abnormal, asymmetrical and accommodative movement pattern. Keen observation will paint a full, functional picture of the client’s gait and movement. This information can be used to program from a deeper level than assessment alone.

Other common contributing factors to FAI include muscle imbalances, structural abnormalities of the femoral head, depravation of oxygen/nutrients to the femoral head and repetitive stressors/loads (e.g., dancing). Evidence also supports the hypothesis that osteoarthritis of the hip is a major etiologic factor in FAI (Clohisy, St. John & Schutz 2010). Additionally, people with excessive ROM at the hip can suffer from impingement, potentially predisposing them to FAI from biomechanical stressors.

Review of Hip Pathomechanics

The hip joint is a ball and socket joint, and its main function is to bear weight (Banerjee & Mclean 2011). The femoral ball slides against the acetabular socket and allows the body to perform movements freely. The joint is supported by bones, cartilage, muscles, ligaments and tendons and has two main components: the acetabulum and the femur. The femoral head fits into and moves against the acetabular surface. The hip joint is capable of wide ranges of motion, including flexion, extension, abduction, adduction and rotation (American Medical Association 2011).

Anatomically, the iliopsoas, gluteus medius, gluteus minimus and gluteus maximus all provide anterolateral stability, as seen in Figures 1 and 2. As mentioned earlier, muscle imbalances can lead to hip dysfunction. For example, clients frequently have tight hip flexors and quadriceps with weaker hamstrings and a weaker gluteus medius and gluteus minimus. This imbalance alters load transfer throughout the kinematic chain, and places excessive load on the hip joint, thus altering the individual’s movement patterns. This is one reason why proper assessment and gait analysis are so important when training a new client.

Before training anyone with FAI, it’s advisable to be thoroughly educated on what happens biomechanically with hip movement. It is vital to understand what happens to a bone when movement occurs as it relates to concentric and eccentric muscle contraction.

Two Types of FAI: Pincer and Cam

Hip impingement can occur with extremes of movement, lack of movement or a combination of both. There are two types of impingement: pincer and cam. Pincer impingement occurs when a bony prominence at the front of the acetabulum places excessive pressure against the neck of the femur (Yuan, Sierra & Trousdale 2008). This impacts ROM and contributes to pain. Pincer lesions are more common in middle-aged active women (Crawford & Villar 2005). Repeated contact between the normal femoral neck junction and the acetabular rim results in labral degeneration, ossification of the acetabular rim and deepening of the acetabulum (Banerjee & Mclean 2011; Crawford & Villar 2005). The causes of pincer impingement include developmental changes, structural changes (such as a retroverted acetabulum), trauma and posttraumatic deformity (Banerjee & Mclean 2011).

In contrast, cam impingement is more common in young, active men (Crawford & Villar 2005) and is attributed to a nonspherical portion of the femoral head placing excessive pressure against the acetabular rim. This is most noticeable with active hip flexion and external rotation in which the position of the femoral head is too large to pass in the acetabulum. Consequently, when the hip is flexed, the rim of the labrum is stressed (Laude, Boyer & Nogier 2007). This is shown in Figure 3.

The causes of cam impingement include developmental issues such as a nonspherical femoral head and Perthes disease, and trauma such as femoral neck fractures and chondral lesions, especially in the acetabulum (Banerjee & Mclean 2011).

Medical and Physical Therapy Treatment Approach

FAI can not only predispose a client to osteoarthritis but may also lead to degenerative labral tears from repetitive compression and sheer forces placed on the hip. It doesn’t matter when the impingement occurs; if the client stresses the joint through overuse, internal structures such as the capsules, supporting ligaments and connective tissues will be negatively affected. This repetitive stress activates pain fibers within the joint and, depending on the client’s physical conditioning, body type and other muscular imbalances, the pain can be acute or insidious.

Excessive hip flexion with external rotation or excessive hip flexion with internal rotation places excessive compression and torsional forces on the hip, particularly the labrum. Muscle imbalances and areas of tightness, particularly in the hip flexors, adductors, piriformis, quadriceps and iliotibial band (IT), all contribute to compressive loading of the hip joint, predisposing it to further mechanical stress. Once the pain reaches a point where it affects daily activities and the ability to play sports, a person has two choices: conservative treatment or surgery. The choice is up to the client and his or her physician.

For many individuals, doctors initially recommend the conservative approach. This approach may include modifying activities, avoiding excessive hip movement and taking nonsteroidal anti-inflammatory medicine, all of which may provide some relief (Keogh & Batt 2008). The role of physical therapy is to improve passive ROM and soft-tissue/joint mobility. A savvy professional will help clients strengthen lateral and posterior musculature, improve core stability and encourage cross-training, such as carefully selected yoga poses and swimming. However, if symptoms continue and do not improve, then the client may be a candidate for surgery.

If surgery is required, the most common procedure is hip arthroscopy (Ng et al. 2010; Crawford & Villar 2005). The underlying hip joint is debrided (damaged or deformed tissue is removed), and the head of the femur is reshaped. After the bone has been reshaped, the normal concave relationship at the junction of the articular surface is recreated, eliminating the cam or pincer lesion. Postoperatively, the patient is allowed to bear weight but must use crutches during the first 4 weeks. Full bony remodeling takes 3 months, and some precautions are necessary to avoid high-impact or torsional forces (Byrd & Jones 2011).

During this time, gentle ROM is emphasized to stimulate the healing process. After 3 months, specific precautions are lifted and functional progression is allowed. The speed with which the individual advances is variable, and full recovery may require another 1–3 months. Thus, people are generally advised that, after surgical correction, they can return to sports in approximately 4–6 months (Byrd & Jones 2011). Another surgical option is the open procedure, which corrects deformities with either an osteoplasty (surgical repair using bone from another part of the body) or acetabular-rim trimming (Clohisy, St. John & Schutz 2010).

Programming Guidelines for FAI

As with programming for any client, it’s vital to take an individualized approach when working with a client who has FAI. To avoid “irritating” the client and to help her achieve her goals, emphasize quality, not quantity. The first step is to understand what type of FAI the client has (cam or pincer). It is crucial that you understand the pathology and communicate with the physical therapist and rehabilitation team, especially postoperatively if that is the case. For optimal outcomes, always consult the client’s physician and/or physical therapist.

Here are some points to consider when designing a training program for a client with FAI:

  • What are the results of the fitness/movement assessment? Use the data to create a safe baseline.
  • Factor in the client’s age, lifestyle, prior/present exercise habits and medical history.
  • Explore how the data affect anatomical, biomechanical, physiological and neurophysiogical demands on the body.

General programming. Focus on lengthening tight musculature and then stabilizing weaker phasic musculature (glutes, hamstring and core). Combine this approach with aquatic therapy and cardiovascular exercise to train the client holistically.

Initially, teach single-plane exercises such as horizontal leg press. You may progress to inverted leg press (avoiding end range), leg curls and hip extension (for example). This will create a foundation for more advanced exercises. When ready, progress the client to biplanar axis exercises, such as diagonal reverse lunge and diagonal forward lunge, to challenge the nervous system. This dynamic movement also recruits muscle stability while targeting the weaker sagittal stabilizers (gluteus medius and minimus) needed in everyday movement. Progress further to compound exercises, such as minisquat with mid row, reverse lunge with overhead medicine ball chop, and forward lunge with trunk rotation holding a medicine ball.

There are several exercises that should be avoided when training a client with FAI:

  • deep squats
  • exercises that involve excessive hip flexion with internal rotation or hip flexion with external rotation
  • plyometrics, particularly box jumps
  • any exercises that cause the client pain

Cardiovascular conditioning. A comfortable cardiovascular component is another essential piece of the programming puzzle. Have the client use machines such as the elliptical trainer, which will provide physiological benefits to the cardiovascular system but also increase circulation.

Strength training. Focus strength training on weaker phasic muscles such as the gluteus maximus/medius/minimus and hamstrings over the quadriceps. Exercise choice and type of equipment will depend on the client’s exercise experience, body type and goals and whether or not the client has had surgery.

Flexibility. Concentrate the stretching protocol on tight hip flexors, quadriceps and the IT band. Introduce stretches in a controlled manner, and offer home practice options, such as a modified lunge.

Core training. Core stabilization is an important aspect of the overall program. Focus on the external obliques, quadratus lumborum and multifidi. Ideal exercises include bridging with a stability ball and standing diagonal trunk rotation with a cable or medicine ball held at chest level. Progress the latter move to a partial lunge with trunk rotation.

As the client improves, integrate more challenging exercises, such as wood chop with reverse lunge. Yoga and Pilates can be good cross-training options, not only for their flexibility and breathing benefits but also for the core strengthening that occurs from moving in multiple directions. Of special note, swimming complements training, owing to the buoyancy principle and the relaxation effect. Most important, when working with any client, if there is uncertainty as to whether or not an exercise will cause pain or damage, ask a physical therapist or physician or do not perform the exercise.

Helping Clients Manage Hip Pain

Hip pain can be experienced by older adults, younger adults and athletes, sometimes with debilitating effects. Remember: As a personal trainer, before working with a client who has FAI you must understand the dynamic anatomy and muscles around the hip complex and their synergistic role. Effective programming that utilizes careful periodization training principles can make a positive difference. However, training can do serious damage if you don’t have a clear mental picture of the movement pathology and muscles involved, among other pertinent biomechanical factors. While working with a client who has FAI may initially be challenging, a professional and well-thought-out plan of action that includes the client’s allied health professional team will garner results and appreciation.

FIGURE 1. Anterior Hip Complex

FIGURE 2. Posterior Hip Complex

FIGURE 3. Cam and Pincer Impingement

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