Conservative management of femoroacetabular impingement (FAI)

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Physical Therapy in Sport 15 (2014) 82e90

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Masterclass

Conservative management of femoroacetabular impingement (FAI) in the long distance runner Janice K. Loudon*,1, Michael P. Reiman Physical Therapy Division, DUMC 100402, Duke University, Durham, NC 27709, USA

a r t i c l e i n f o

a b s t r a c t

Article history: Received 1 August 2013 Received in revised form 15 January 2014 Accepted 13 February 2014

Femoroacetabular impingement (FAI) is one cause of anterior hip pain that may occur in a long distance runner. By definition FAI is due to bony abutment of the femoral neck and the acetabulum. This occurs primarily with end-ranges of hip flexion and adduction. An understanding of running mechanics and performing a thorough examination will help the clinician provide an appropriate intervention for these athletes. A course of conservative treatment that includes patient education, manual therapy and strengthening should be tried prior to surgical management. Ó 2014 Elsevier Ltd. All rights reserved.

Keywords: Hip Lower extremity kinematics Joint mobilization

1. Introduction Running is a popular exercise modality for many individuals of all ages. Unfortunately, running athletes, especially long distance runners, are commonly afflicted with various lower extremity injuries. On average, hip or pelvic injury rate is 3.3%e11.5% of total lower extremity injuries in long distance runners (van Gent, Siem, van Middelkoop, van Os, Bierma-Zeinstra, & Koes, 2007). Although not the most common area for injury complaint, hip pain can range from severe problems, such as stress fractures or arthritis, to mild problems, such as muscle strains or bursitis. Recently, femoroacetabular impingement (FAI) has been increasingly recognized as a cause of anterior hip pain. Femoroacetabular impingement occurs when there is limited joint clearance between the femoral headeneck junction and the acetabular rim. Given the number of disorders capable of causing hip pain, the fact that hip pathology can refer pain to other areas, and pathology elsewhere can refer pain to the hip, a careful and comprehensive examination of this joint must be completed. An accurate diagnosis of FAI will help guide the clinical decision making process whether to refer for surgery or to begin conservative management. Various mechanical scenarios may occur setting the runner up for FAI. A slight change in muscle length or limited joint play will alter the normal joint motion pathway. For example, if the tensor

* Corresponding author. E-mail addresses: [email protected], [email protected] (J. K. Loudon). 1 Permanent address: 10121 Delmar, Overland Park, KS 66207, USA. Tel.: þ1 913 579 6303. http://dx.doi.org/10.1016/j.ptsp.2014.02.004 1466-853X/Ó 2014 Elsevier Ltd. All rights reserved.

fascia latae (TFL) dominates hip flexion movement instead of the iliopsoas, normal arthrokinematics are compromised since the TFL inserts at a relative greater distance from the joint axis creating an internal rotation bias with hip flexion (Sahrmann, 2002). Another example is a decrease in posterior joint play. Lack of posterior femoral glide will create an impingement during hip flexion as the femoral neck hits the acetabulum. The impingement may be further exacerbated with femoral internal rotation. Limiting hip adduction and internal rotation during functional activities has been shown to decrease hip pain in a runner with FAI and labral tear (Austin, Souza, Meyer, & Powers, 2008). Beyond muscle balance and arthrokinematics, FAI may occur due to a bony abutment of the femoral neck against the acetabular rim, which may occur by two mechanisms known as ‘cam’ or ‘pincer’ impingement, although most commonly by a mixture of both (Beck, Kalhor, Leunig, & Ganz, 2005; Philippon, Maxwell, Johnston, Schenker, & Briggs, 2007). Cam impingement, where the femoral head has an abnormally large radius, causes shear forces on the acetabular rim. Pincer impingement occurs where an abnormality of the acetabulum results in impingement against an often normal femoral neck. Cam and pincer impingement rarely occur in isolation, and the combination has been termed mixed camepincer impingement (Beck et al., 2005; Philippon et al., 2007). Both types can result in damage to the acetabular cartilage and labrum and predispose the hip to osteoarthritis (Beck et al., 2005). Early detection and correction is helpful in preventing labral injuries. The aim of this Masterclass article is to discuss the conservative management of FAI in runners. Anatomy, hip biomechanics, hip examination, differential diagnosis and conservative management of the hip will be discussed.

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2. Hip anatomy The hip joint is a large spheroidal joint. Due to its architectural arrangement and ligamentous support the hip is inherently a very stable joint. It also has a moderate amount of mobility which allows for activities of daily living, walking and running. The numerous muscles that attach about the hip are important for control and balance of the lower extremity and spine. The joint capsule is a loose fibrous capsule that encompasses the outer portion of the hip joint. The fibers of the capsule spiral from the joint to the intertrochanteric line forming a fibrous collar around the femoral neck. Longitudinal fibers are found within the anterior capsule. Along the outer surface of the acetabulum is an acetabular labrum. The labrum is similar to the labrum of the shoulder. It is made of fibrocartilage and increases the articular surface area by 22% and acetabular volume by 33% and is believed to create a seal in the hip joint (Seldes, Tan, Hunt, Katz, Winiarsky, & Fitzgerald, 2001). The labrum allows the acetabulum to hold more than ½ the head of the femur and thus provides stability to the joint. The labrum contains free nerve endings and sensory end organs in its superficial layer which may participate in nociceptive and proprioceptive function (Kim & Azuma, 1995). The muscles that make-up the anterior quadrant of the hip and are primarily involved with FAI are the hip flexors. The hip flexors are found anterior to the hip joint axis and include the iliopsoas (psoas major, iliacus), sartorius, rectus femoris, tensor fasciae latae, and the pectineus. The iliopsoas is formed by the psoas major which originates on the transverse processes of all five lumbar vertebrae and the vertebral bodies and anterior discs of the 12th thoracic vertebra and all five lumbar vertebrae and inserts on the lesser trochanter. The psoas major is commonly short in athletes and will cause the hip to remain in a position of flexion and the lumbar spine to extend. The other component of the iliopsoas is the iliacus which originates from the iliac fossa and also inserts on the lesser trochanter. Fibers of the iliopsoas muscle attach to the anterior joint capsule and contraction of this muscle may help to prevent pinching of the anterior capsule (Alpert, Kozanek, Li, Kelly, & Asnis, 2009; Blankenbaker & Tuite, 2013; Blankenbaker, Tuite, Keene, & del Rio, 2012). A second hip flexor, the sartorius, is a long strap-like muscle that originates on the anterior superior iliac spine and inserts on the proximal medial tibia as a common tendon with the semitendinosus and gracilis, into the pes anserine. Besides flexing the hip, the Sartorius also abducts and externally rotates the femur. The rectus femoris is the only part of the quadriceps that crosses the hip joint and serves as a hip joint flexor. It originates on the anterior inferior iliac spine and inserts on the tibial tubercle. Another strong hip flexor is the TFL that originates on the external rim of the iliac crest and is the anterior muscle that attaches to the iliotibial band. At the hip, the TFL can be tight causing not only hip flexion, but femoral internal rotation. The final hip flexor, the pectineus is a short broad muscle that attaches from the superior ramus of the pubic bone to the pectineal line of the femur. Besides hip flexion, the pectineus also adducts the femur. Other muscles that assist with hip flexion are the adductor longus, adductor brevis, adductor magnus, gluteus minimus, and the anterior fibers of the gluteus medius. 3. Functional biomechanics of the hip 3.1. Hip kinematics during walking and running The hip joint has key motion in all three planes during the walking and running gait cycle but primarily this motion occurs in the sagittal plane (Kadaba, Ramakrishnan, Wootten, Gainey,

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Gorton, & Cochran, 1989; Perry, 1992). In the sagittal plane, flexion and extension of the hip joint averages around 40 in walking and 65e85 in running. Hip flexion helps with absorption of impact forces during initial ground contact. From mid-support to take-off the hip joint moves from flexion to extension helping to propel the athlete’s body forward. As the limb moves into the swing phase, the hip continues to extend. The hip will then move into flexion during mid- and late-swing to ready the foot for contact. During gait, synchronous motion occurs at the pelvis, posterior tilt of the pelvis occurs during hip flexion and anterior tilt corresponds to hip extension. Inadequate anterior tilt or rotation of the pelvis during late stance phase may cause the runner to excessively extend the femur; this may increase tensile stresses to the iliofemoral ligament and anterior joint capsule (Torry, Schenker, Martin, Hogoboom, & Philippon, 2006). Motion in the frontal and transverse planes is much less than what is found in the sagittal plane. In the frontal plane the hip moves in relation to the action of the pelvis. At initial contact, the hip is in a neutral position to slight adduction. The hip continues to display slight hip adduction (5 ) up until mid-stance. After mid-stance the hip begins to abduct and is in a position of about 10 of hip abduction as the foot leaves the ground. During swing the hip is relatively neutral. Motion at the hip will mirror the motion of the pelvis in this plane and this combined motion is thought to help minimize shoulder and head movement (Novacheck, 1998). Increased femoral adduction has been linked to various injuries in the knee and hip joints during running (Ferber, Hreljac, & Kendall, 2009; Ferber, Noehren, Hamill, & Davis, 2010). Hip motion in the transverse plane is similar in walking and running. The hip is in slight external rotation and then moves into internal rotation up until mid-support (Gerringer, 1995). The hip then returns to a more neutral position at take-off (Mann, 1989). A variation in hip position has been reported in swing (internally rotated versus neutral); although it would seem that a neutral hip would be more advantageous than excessive internal rotation. 3.2. Hip forces during walking and running Measurement of vertical ground reaction forces (VGRF) is one way to estimate forces on the hip during walking and running. VGRF during walking is estimated to be 1.15 bodyweight for females and 1.23 BW for males (Perry, 1992). Jogging forces are estimated to be 2.36 BW for females and 2.45 BW for males. The increase in VGRF that occurs from transitioning from walking to jogging is a function of the change in center of gravity velocity (Gerringer, 1995). It has been reported that increasing step/stride rate will decrease joint forces (Clarke, Cooper, Hamill, & Clark, 1985; Heiderscheit, Chumanov, Michalski, Wille, & Ryan, 2011). 3.3. Hip muscle activity during running Running involves a stance phase and swing phase. In running the stance phase is quick with only about 0.2e0.4 s of time spent per step. During the initial phase of stance the body is absorbing the ground reaction forces. The lower limb is primarily working eccentrically to control the forward momentum of the body. At the hip, the primary muscles working are the quadriceps, hip extensors, hip abductors, and hamstrings. The hip joint extensor, the gluteus maximus, generates power during this phase to pull the body forward by actively extending the hip after swing (Siverling, O’Sullivan, Garofalo, & Moley, 2012). In the frontal plane, the gluteus medius is working to control/slow frontal plane lateral pelvic tilt. The hamstring is active before foot strike and demonstrates continued EMG activity into the propulsion phase. Its initial activity is responsible for slowing the rapidly extending knee in preparation for contact.

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Once the runner’s body moves anterior to the stance leg, the propulsion phase begins until the foot leaves the ground. The concentric contraction of the lower limb muscles along with stored potential energy in the tendons help to propel the body forward. During propulsion the ankle, knee and hip combine in a triple extension movement to provide propulsion upwards and forwards. The calf, quadriceps, hamstring and gluteal activity during the propulsion phase is less than during the braking phase, because the propulsion energy comes mainly from the recoil of elastic energy stored during the first half of stance. The gastrocnemius generates the primary propulsion during the propulsive phase (Winter, 1983). In addition, the hip flexors are dominant in the propulsion phase and this activity continues through the first half of swing. This muscle group initially is decelerating hip extension, but then becomes the primary force generation for forward swing. The gluteus medius contracts concentrically to abduct the hip and provide hip lift (Novacheck, 1998). During the swing phase of running the hip flexors work concentrically to bring the swing limb forward to ready it for impact. The gluteus maximus works eccentrically to control this motion (Marzke, Longhill, & Rasmussen, 1988; Stern, Pare, & Schwartz, 1980). The hip abductors and external rotators are working eccentrically to control motion in the frontal and transverse planes. 4. Examination for FAI 4.1. Differential diagnosis Examination of the hip region can be quite complex due to coexistent pathology, secondary dysfunction, or coincidental findings (Byrd, 2005; Domb, Brooks, & Byrd, 2009; Reiman, Weisbach, & Glynn, 2009). According to Byrd, the clinical assessment can be 98% reliable at detecting the presence of a hip joint problem; although the exam may be poor at defining the exact nature of the intraarticular disorder (Byrd, 2007). Often times, patients with FAI get misdiagnosed early on and are treated for a variety of diagnoses such as back pain, hip pain, groin pain, bursitis, piriformis syndrome, tendonitis of iliopsoas, groin strain, apophysitis, and “growing pains” (Byrd, 2007). Differential diagnosis of FAI from other forms of anterior hip pain may include hip flexor strain, iliopsoas bursitis, snapping hip syndrome, femoral acetabular impingement, labral tear and femoral neck stress fracture. Ruling out the potential for stress fractures and fractures of the femur can be assisted with the fulcrum test (SN 0.88e0.93) (Johnson, Weiss, & Wheeler, 1994; Kang, Belcher, & Hulstyn, 2005) and patellar-pubic percussion test (SN 0.95) (Reiman, Goode, Hegedus, Cook, & Wright, 2012) respectively. The diagnostic accuracy of the patellar-pubic percussion test is much stronger than the fulcrum stress fracture test. Labral tear pathology is often similar in presentation to FAI. The subjective and objective findings, radiographic measurements, and special testing in particular are similar for these pathologies. In fact, one of the primary mechanisms for hip labral tear is FAI (Beaule, O’Neill, & Rakhra, 2009; Groh & Herrera, 2009; Kelly, Weiland, Schenker, & Philippon, 2005). 4.2. Subjective report A comprehensive examination and development of a precise, individualized physical therapy program can assist the runner attempt to avoid surgical intervention and return to running at normal levels. The exam should begin with a thorough subjective exam. The following components should be included: patient profile, pain

description, location and behavior, aggravating factors, mechanism and history of current complaint and past medical history. Once the clinician completes the subjective exam a decision should be made to refer for further testing, treat and refer, or treat. 4.2.1. Patient profile The majority of patients with FAI are involved in sports (Nogier et al., 2010). Related to the bony deformities at the joint, a cam impingement is more common in young males whereas a pincertype impingement is more common in middle-aged females (Lavigne, Parvizi, Beck, Siebenrock, Ganz, & Leunig, 2004). If the runner also works at a desk job and sits all day, this posturing tends to create tightness in the hip flexors which can add to impingement symptoms. 4.2.2. Pain description, location, and behavior Runners who present with symptoms of FAI often complain of pain in the groin and/or deep hip. The pain can be described as a dull ache or a sharp sensation. In fact, the lack of groin pain can help rule out the possibility of FAI with a reported SN between 0.96 and 1.00 (Keeney, Peelle, Jackson, Rubin, Maloney, & Clohisy, 2004; McCarthy & Busconi, 1995). A report by the runner of a dull ache or a sharp pain with mechanical clicking and giving way can be diagnostic of an FAI with a reported SN of 1.00 and specificity (SP) of 0.85 (Burnett, Della Rocca, Prather, Curry, Maloney, & Clohisy, 2006; Narvani, Tsiridis, Kendall, Chaudhuri, & Thomas, 2003). The pain can progress from localized pain in the anterior thigh and in the region of inguinal ligament to a deep aching pain in the posterior aspect of the hip joint (Sahrmann, 2002). Pain is usually transient and occurs primarily during motion. When asked to pinpoint their pain, they will often demonstrate a “C” sign, described by Byrd (2005). To gain a more objective measure of pain and function, outcome measures such as the Lower Extremity Functional Scale (LEFS) can be used. For determining improvement with selected interventions, the Global Rating of Change (GROC) score can be used, or more specific to the hip, the Hip Outcome Score (HOS) and the International Hip Outcome Tool (iHOT) have been suggested (Griffin, Parsons, Mohtadi, & Safran, 2012; Lodhia, Slobogean, Noonan, & Gilbart, 2011; Mohtadi et al., 2012). 4.2.3. Aggravating factors Runners with FAI will commonly experience pain during excessive hip flexion with/out medial femoral rotation and activities such as squatting (Lamontagne, Kennedy, & Beaule, 2009). Straight plane activities such as straight ahead walking or even running are often well tolerated, while twisting maneuvers such as simply turning to change direction may produce sharp pain, especially turning toward the symptomatic side which places the hip in internal rotation. Sitting may be uncomfortable, especially if the hip is placed in excessive flexion or if sitting is prolonged. Running an incline causing more hip flexion may bring on the pain. During cross-training activities, riding a recumbent cycle may impinge the hip due to the increased hip flexion. 4.3. Objective exam 4.3.1. Posture Individuals with FAI commonly present with a swayback posture (Sahrmann, 2002). As described by Kendall, McCreary, Provance, Rodgers, and Romani (2005) swayback posture consists of loss of normal lumbar curve with the upper back sway backed and pelvis swayed forward. The pelvis is tilted posteriorly and the hip joint is extended. In this type of posture, the external oblique muscles and iliopsoas are excessively long. Other hip flexors such as the rectus femoris and tensor fasciae latae are short. The line of

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gravity moves posteriorly to the hip joint with this type of posture, resulting in disuse atrophy of the gluteal muscles.

Text Box: Objective Examination for FAI Standing  Posture  Lumbar spine Range of Motion (with repeated motion)  Single leg stance (right and left)  Single leg step down (right and left)  Squatting  Walking Gait  Running Gait Supine  Hip flexion range of motion (ROM); active and passive  Hip internal/external rotation ROM (active/passive)  Hip adduction/abduction ROM (active/passive)  Joint play (anterior/posterior glide)  Thigh thrust to rule out SI joint  Straight leg raise (monitor trochanter and hamstring length)  Thomas test (hip flexor length)  Muscle tests (iliopsoas, TFL)  Flexion IR test  Palpation Prone  Active hip extension (palpating for hams vs. glut activity)  Hip internal/external rotation ROM (active/passive)  Muscle tests (hamstrings, gluteus maximus)  Palpation Quadruped  Static selected position  Rock back Sidelying  Modified Ober’s test  Muscle test (gluteus medius) Sitting  Hip internal/external rotation ROM (active/passive)  Muscle test (Iliopsoas) 4.3.2. Hip joint mobility Range of motion (ROM) testing for the hip is an imperative component of FAI differential diagnosis. Motion testing includes active and passive ROM for hip flexion, internal and external rotation, adduction and abduction. Objectively, there will be a loss of ROM, particularly hip flexion, IR and/or adduction (Burnett et al., 2006; Clohisy, Knaus, Hunt, Lesher, Harris-Hayes, & Prather, 2009; Philippon et al., 2007; Prather, Hunt, Fournie, & Clohisy, 2009; Song, Ito, Kourtis, Safran, Carter, & Giori, 2012). Functional evaluation of hip ROM has been described as a useful tool in the differential diagnosis of FAI (Audenaert, Van Houcke, Maes, Vanden Bossche, Victor, & Pattyn, 2012). Movements such as squatting can be used for this purpose. In addition to range of motion, joint play should also be assessed. The most important directions to check are anterior and posterior glides. Particular attention should be given to insufficient posterior glide joint play of the femur during hip flexion. The stiffness of the hip extensors and posterior joint structures, as well as the excessive flexibility of anterior hip joint structures results in a path of least resistance to anterior glide (Lewis, Sahrmann, & Moran, 2007). 4.3.3. Muscle length/strength assessment An important component of the exam is to perform an assessment of the muscles’ length and strength about the hip. Commonly

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the iliopsoas is long and weak, the TFL is short and dominant, and the gluteus maximus is short and weak. The Thomas test (hip flexor length) is used to assess the length of the single joint (iliopsoas) and two joint hip flexors (TFL, rectus femoris) (Fig. 1). Detection of a deep click when lowering the leg to be assessed may be indicative of a labral tear (SN 0.89, SP 0.92) (McCarthy & Busconi, 1995). Hip abductor length is assessed with the modified Ober’s test. The modified Ober test is performed with the knee in only slight knee flexion to prevent confounding of a tight rectus femoris which may limit hip abduction with the knee flexed to 90 . Commonly the TFL will be tight and in addition to limited hip adduction the femur may tend to rotate internally. Hamstring length is assessed using the straight leg raise test. The athlete should achieve 80 according to Kendall et al. (2005). The clinician may bias internal or external rotation and see if range is gained by the change in rotation. Strength tests should be performed on the following muscles: iliopsoas, gluteus medius, gluteus maximus, hamstrings and TFL. Commonly the gluteus medius and gluteus maximus and iliopsoas are weak, especially when correlated with a hip labral tear (Lewis et al., 2007). 4.3.4. Movement analysis The next component of the exam is a movement analysis. The runners is examined performing various movements: forward bending, single leg stance, single leg step down, straight leg raise, quadruped with rocking back, and walking and running gait. As the athlete performs forward bending, check for the quality of movement, commonly the motion occurs primarily through the lumbar spine in the athlete with FAI as they attempt to avoid painful hip flexion. Next, the runner will perform single leg stance, first on the uninvolved side and then on the involved side. Have the individual hold the stance for up to 30 s to check for balance and/or reproduction of symptoms. Check for the quality of the movement, if the TFL dominates, then commonly internal rotation will occur. Next the athlete will perform a single leg step down on a standard 7e8 inch step. The clinician should monitor the knee for medial drift that indicates increased hip adduction and internal rotation. Additionally, the athlete should be questioned for concordant symptoms during the maneuver. Further movement analysis includes monitoring the greater trochanter as the runner performs a straight leg raise (Harris-

Fig. 1. Thomas test.

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Hayes, Sahrmann, & Van Dillen, 2009; Van Dillen et al., 2001). This can be performed following the SLR for hamstring length as mentioned above. The femur should stay relatively stable; take note if it moves anteriorly with hip flexion and if this maneuver brings on the concordant pain. The clinician then can add hip abduction and external rotation to see if this decreases pain. These findings would indicate poor joint play and perhaps a dominant movement pattern of the TFL. In the prone position, the clinician palpates the hamstrings and gluteal muscles as the runner performs hip extension with the knee straight. If the hamstrings fire before the gluteal muscles then the hamstrings are the dominant hip extensors. This patterning creates an anterior glide of femoral head. Have the runner next move to a quadruped position and note the position of the hip. Check to see if it is less than 90 of hip flexion which may indicate an avoidance of hip flexion or tightness of the posterior chain muscles. From this position have the athlete rock back toward his/her heels. In runners with hip impingement the motion primarily comes from lumbar spine, similar to what was found in standing forward bending. Walking and running gait should be examined, preferably with some type of video system in order to play it back and to slow it and freeze frame it for precise analysis. Observe the runner in three planes and take note of deviations from the normal gait that was previously described. It has been shown that individuals with FAI display less hip ROM during walking gait than those with normal hips. Kennedy et al. studied 18 individuals with cam FAI and reported that those with FAI exhibited lower peak abduction angles and smaller frontal and sagittal plane excursions compared to the control group (Hunt, Gunether, & Gilbart, 2013; Kennedy, Lamontagne, & Beaule, 2009). Hunt et al. found that 30 individuals with FAI exhibited significantly less maximum hip extension, adduction, and internal rotation during stance compared to normal (Hunt et al., 2013). These authors proposed that the pain associated with increases in adduction and internal rotation may provoke a learned inhibition response during movement that increase with time. This is probable since these deficient gait kinematics resolve following hip surgery (Rylander, Shu, Andriacchi, & Safran, 2011). During running, the clinician should observe for good pelvic control. Increased lumbar flexion and posterior tilt of the pelvis may result in compensation of isolated hip extension which may cause strain to the anterior hip. 4.3.5. R/O spine/sacroiliac joint Repeated motion that centralizes/peripheralizes the patient’s extremity pain has been shown to help rule out (SN 0.92) discogenic related pathology of the lumbar spine. The motions employed were repeated trunk flexion, extension and side-bending (Donelson, Aprill, Medcalf, & Grant, 1997). The sacroiliac (SI) joint is often considered a diagnosis of exclusion due to the complexity of SI joint related pathological diagnosis. Cluster testing has been previously suggested, with the individual thigh thrust test demonstrating the strongest ability to rule out SI joint related pathology (SN 0.88) (Laslett, Aprill, McDonald, & Young, 2005). 4.3.6. Special tests A recent systematic review shed light on the fact that hip special testing for FAI (and many other pathologies) has significant limitations with respect to diagnostic accuracy (Reiman, Goode, Hegedus, Cook, & Wright, 2013). As previously mentioned, the Thomas test is both SN and SP for labral tear pathology. The pooled diagnostic SN of the flexioneadductioneinternal rotation (FADDIR) test (Fig. 2) was 0.94 with a reference standard of MRA and 0.99 with a reference standard of arthroscopy (Reiman et al., 2013).

Fig. 2. Flexioneadductioneinternal rotation test.

Another less commonly reported special test is the flexion IR test. This test has a similar movement as the FADDIR test without the adduction. A pooled SN of 0.96 was reported for this test (Reiman et al., 2013). While several other tests have been reported for FAI, including the FABER and Scour tests, their diagnostic accuracy is currently limited (Reiman et al., 2013). Clinical special tests are a small component of a comprehensive clinical examination. 4.3.7. Palpation Finally, palpate over specific structures, such as the hip flexor muscles, greater trochanter, iliotibial band, and gluteus medius muscle, to further localize the source of pain. For instance, tenderness may be present over the anterior soft tissues in a hip flexor muscle strain or iliopsoas bursitis and over the greater trochanter in trochanteric bursitis. Studies implicating the psoas major as a potential contributor to labral tears in the hip (Blankenbaker et al., 2012; Domb, Shindle, McArthur, Voos, Magennis, & Kelly, 2011; Tey, Alvarez, & Rios, 2012) would seem to suggest palpation of this muscle as a necessary component of examination for FAI. 4.4. Imaging There are currently several methods of assessing the degree of FAI by use of radiographs, computed tomography (CT) and magnetic resonance imaging (MRI) scans, which can be used in conjunction with arthroscopy to assess the damage caused to the underlying structures of the hip. As with all components of a comprehensive examination, reliance on imaging alone for diagnosis of FAI is not suggested. Pathological changes suggestive of FAI and labral tear in the hip have been shown in asymptomatic individuals (Gerhardt, Romero, Silvers, Harris, Watanabe, & Mandelbaum, 2012; Hartofilakidis, Bardakos, Babis, & Georgiades, 2011; Jung, Restrepo, Hellman, AbdelSalam, Morrison, & Parvizi, 2011; Schmitz, Campbell, Fajardo, & Kadrmas, 2012; Silvis et al., 2011). Radiographs are helpful to not only assess for the presence or absence of abnormal morphology of FAI, but also for the assessment of alternative causes of hip pain, including, but not limited to: osteoarthritis, femoral head avascular necrosis (AVN), fracture, tumors, and osseous lesions. Magnetic resonance imaging is more SN in the detection of AVN, non-displaced fracture (including stress fracture), and osseous lesions. While there are several views on radiographs to observe for FAI, lateral projection(s) can be utilized to observe for an insufficient

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headeneck offset (cam FAI). The most commonly described assessment for this view is the alpha angle (Fig. 3). This angle is defined as the angle between a line through the center of the femoral head that parallels the femoral neck and a line from the center of the femoral head to the point where there is a deviation of a best-fit circle of the head and the adjacent proximal femur. The alpha angle can be measured from the anterioreposterior (AP) and cross-table lateral radiographs. An abnormal alpha angle has traditionally been considered one that is greater than 50e55 (Kassarjian, 2006; Notzli, Wyss, Stoecklin, Schmid, Treiber, & Hodler, 2002); although more recent findings suggest larger angles above these standard to discriminate those individuals with and those without pathological FAI (Kumar & Aggarwal, 2011; Sutter, Dietrich, Zingg, & Pfirrmann, 2012). The AP pelvis radiograph view can be used to examine for pincer FAI. If the anterior wall extends lateral to the posterior wall superiorly there is cranial acetabular retroversion, predisposing to pincer FAI. This is a so-called crossover or figure-of-eight sign (Fig. 4) (Anderson, Peters, Park, Stoddard, Erickson, & Crim, 2009; Jamali et al., 2007; Reynolds, Lucas, & Klaue, 1999; Tonnis & Heinecke, 1999). Additionally, acetabular overcoverage can be variable (e.g. acetabular protrusion and coxa profunda) Global acetabular retroversion exists when the entire anterior wall is lateral to the posterior wall. All of these pathomorphologies from the acetabular component of the hip can contribute to pincer FAI. The pathomorphological changes of insufficient femoral heade neck offset (alpha angle) and acetabular overcoverage or retroversion can also be measured with MRI, MRI with arthrogram (MRA) and CT. Comparison to surgical reference standard suggests the diagnostic accuracy of radiographs (SN 91, SP 98) (Kalberer, Sierra, Madan, Ganz, & Leunig, 2008) are favorable to CT scan (SN 92e97, SP 87e100) (Nishii, Tanaka, Sugano, Miki, Takao, & Yoshikawa, 2007; Yamamoto, Tonotsuka, Ueda, & Hamada, 2007) and are superior to MRA measuring alpha angle (SN 39%, SP 70%) (Lohan, Seeger, Motamedi, Hame, & Sayre, 2009).

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Fig. 4. Crossover sign of right hip. Anterior acetabular rim (solid line) crosses over and is more lateral than posterior acetabular rim (dashed line).

Initially, the patient is educated on avoidance of compromising positions such as extremes of hip flexion and internal rotation. Prolonged sitting should be minimized, but if it is necessary the athlete should practice leaning back every 5e7 min while sitting to decrease hip flexion (Emara, Samir, Motasem el, & Ghafar, 2011).

The athlete will not be allowed to run until pain-free hip motion returns. Other cross-training modes such as walking or swimming are suggested. Cycling should be avoided since it involves simultaneous hip flexion and internal rotation. Although the success of conservative management for FAI is reported to be inconclusive, (Bedi & Kelly, 2013) success with conservative care has been reported in three recent publications (Austin et al., 2008; Emara et al., 2011; Wright & Hegedus, 2012). A recent systematic review demonstrates favorable findings for conservative intervention in these patients, but does suggest caution with interpretation of the findings due to limited investigation (Wall, Fernandez, Griffin, & Foster, 2013). The primary goals of conservative management are to improve posterior glide of femur; strengthen hip musculature in open and closed chain and correct faulty movement patterns. Given the importance of three-dimensional control of the hip with running, treatment should attempt to restore function in all three planes of movement. Improvement of femoral posterior glide is achieved using joint mobilization. The leg to be mobilized is flexed and adducted (as well as internally rotated with the foot fixed on the table) to just short of symptoms and/or restriction. The clinician then provides a posterior-laterally directed force longitudinally through the distal

Fig. 3. Dunn lateral radiograph demonstrating alpha angle (marked with dashed white line).

Fig. 5. Supine hip posterior-lateral hip mobilization.

5. Conservative management

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femur if tolerated (Fig. 5). It is important that the patient feel the stretch in the posterior-lateral hip and not anterior joint pinching pain as this may irritate the patient’s symptoms. Joint mobilization should be followed with self-mobilization (Fig. 6) and active exercise to maintain mobility. Quadruped rock backs (Fig. 7) are used to promote the posterior glide of the femoral head and to stretch the hip extensors. Passive hip flexion is also performed to facilitate this motion. Passive motion is preferred over active motion as to alleviate the influence of the hip flexors. Gluteus medius and maximus strengthening should begin in non-weight-bearing positions, focusing on form and endurance of the muscle. The runner should be able to elicit contraction of the deep lumbopelvic stabilizers when performing open-chain hip exercises. Examples of these exercises are prone hip extension with knee flexion, prone hip lateral rotation, and sidelying hip abduction with lateral rotation. Closed chain exercises are clinically appropriate for the running athlete. If tolerated, a lunge exercise provides high level gluteus medius (42  21% EMG) and gluteus maximus (44  23% EMG) muscle activation (Distefano, Blackburn, Marshall, & Padua, 2009). Other high level activation exercises appropriate for gluteal strengthening in the running athlete include standing hip hikes, single-leg squats, and the forward step-up (Ayotte, Stetts, Keenan, & Greenway, 2007; Bolgla & Uhl, 2005; Distefano et al., 2009). Plyometric exercises may be indicated, if tolerated, to improve propulsion power and speed. Neuromuscular re-education of the lumbar and pelvic stabilizers is a foundation of treatment for most runners. Form and the ability to maintain a neutral spine is begun in non-weight-bearing positions and gradually progressed to seated, standing, squatting and lunging positions. Gluteal contraction during standing and at heel strike during walking and running is also important to initiate. This type of training is necessary before the runner is allowed to return to a full running program. Taping or a strapping device (S.E.R.F. Strap, Don Joy Orthopaedics, Inc., Vista, CA) may provide feedback to help maintain hip position. The S.E.R.F. strap has been shown to help minimize hip add and IR during a single leg step down and running in a single case design (Austin et al. 2008). 5.1. Return to running Recently, the effect of increasing step rate on joint forces has been reported in the literature (Heiderscheit et al., 2011). The

Fig. 6. Standing posterior-lateral hip self-mobilization.

Fig. 7. Quadruped rock back with belt lateral distraction.

runner with FAI may benefit from increasing step rate to decrease forces on the hip. Additionally, decreasing the amount of hip extension during terminal stance will help with tensile stresses on the anterior hip (Lewis et al., 2007). When satisfactory muscular control is regained and running form is believed to be correct, they may attempt to return to running. Once the athlete is ready to return to running a specific graded program is required. This program considers the amount of time laid-off from running and starts at 60% of pre-injury state (intensity and duration). First, the runner should begin on softer surfacesdsuch as grass or track. A treadmill or narrow straight trail should be avoided to prevent hip adduction and internal rotation. Form must be maintained, with no emphasis on speed. As form and confidence improves, and pain is not present, speed may be increased gradually. Other recommendations include: 1) include a dynamic warm-up, 2) do not run consecutive days for the first month and 3) cross-train. Increasing mileage too quickly or making a sudden change in the training program, such as adding hills or sprints can result in the return of pain and dysfunction.

5.2. Need for surgical treatment The extent to which conservative intervention is successful in the runner with FAI has not been fully elucidated. In fact, conservative intervention for any type of individual with FAI is still undetermined. As previously mentioned, a recent review of the literature suggests initial non-operative treatment as a potential capable means for patients with FAI (Wall et al., 2013). Confounding the decision-making for surgical intervention is the fact that asymptomatic individuals have demonstrated abnormal morphologic radiographic findings suggestive of FAI and labral tear (Gerhardt et al., 2012; Hartofilakidis et al., 2011; Jung et al., 2011; Schmitz et al., 2012; Silvis et al., 2011). Therefore, the need for surgical intervention should not be determined by imaging alone. Dependent on multiple factors such as the runner’s opinion, clinical presentation, presence/absence of co-morbid conditions, and time in the season (e.g. are they competing in the season’s elite event) it suggested that at least 4e6 weeks of conservative intervention be employed prior to surgical treatment. This is a very general recommendation that must be individualized to the patient.

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6. Conclusion This Masterclass article has presented the examination and conservative treatment for FAI in the long distance runner. In addition, running and walking kinematics and kinetics are described. Improvement of posterior glide of the femur and strengthening the hip musculature should help with signs and symptoms of FAI. Modification in running style will also help with getting the athlete back to running. Conflict of Interest There are no conflicts of interests. Funding No funding source was used for this manuscript. References Alpert, J. M., Kozanek, M., Li, G., Kelly, B. T., & Asnis, P. D. (2009). Cross-sectional analysis of the iliopsoas tendon and its relationship to the acetabular labrum: an anatomic study. American Journal of Sports Medicine, 37(8), 1594e1598. http://dx.doi.org/10.1177/0363546509332817. Anderson, L. A., Peters, C. L., Park, B. B., Stoddard, G. J., Erickson, J. A., & Crim, J. R. (2009). Acetabular cartilage delamination in femoroacetabular impingement. Risk factors and magnetic resonance imaging diagnosis. Journal of Bone and Joint Surgery, 91(2), 305e313. http://dx.doi.org/10.2106/jbjs.g.01198. Audenaert, E., Van Houcke, J., Maes, B., Vanden Bossche, L., Victor, J., & Pattyn, C. (2012). Range of motion in femoroacetabular impingement. Acta Orthopaedica Belgica, 78(3), 327e332. Austin, A. B., Souza, R. B., Meyer, J. L., & Powers, C. M. (2008). Identification of abnormal hip motion associated with acetabular labral pathology [Case Reports] Journal of Orthopaedic and Sports Physical Therapy, 38(9), 558e565. Ayotte, N. W., Stetts, D. M., Keenan, G., & Greenway, E. H. (2007). Electromyographical analysis of selected lower extremity muscles during 5 unilateral weight-bearing exercises. Journal of Orthopaedic and Sports Physical Therapy, 37(2), 48e55. Beaule, P. E., O’Neill, M., & Rakhra, K. (2009). Acetabular labral tears. Journal of Bone and Joint Surgery, 91(3), 701e710. http://dx.doi.org/10.2106/jbjs.h.00802. Beck, M., Kalhor, M., Leunig, M., & Ganz, R. (2005). Hip morphology influences the pattern of damage to the acetabular cartilage: femoroacetabular impingement as a cause of early osteoarthritis of the hip. Journal of Bone and Joint Surgery. British Volume, 87(7), 1012e1018. http://dx.doi.org/10.1302/0301620x.87b7.15203. Bedi, A., & Kelly, B. T. (2013). Femoroacetabular impingement. Journal of Bone and Joint Surgery, 95(1), 82e92. http://dx.doi.org/10.2106/jbjs.k.01219. Blankenbaker, D. G., & Tuite, M. J. (2013). Acetabular labrum. Magnetic Resonance Imaging Clinics of North America, 21(1), 21e33. http://dx.doi.org/10.1016/ j.mric.2012.09.006. Blankenbaker, D. G., Tuite, M. J., Keene, J. S., & del Rio, A. M. (2012). Labral injuries due to iliopsoas impingement: can they be diagnosed on MR arthrography? AJR. American Journal of Roentgenology, 199(4), 894e900. http://dx.doi.org/10.2214/ ajr.11.8211. Bolgla, L. A., & Uhl, T. L. (2005). Electromyographic analysis of hip rehabilitation exercises in a group of healthy subjects. Journal of Orthopaedic and Sports Physical Therapy, 35(8), 487e494. Burnett, R. S., Della Rocca, G. J., Prather, H., Curry, M., Maloney, W. J., & Clohisy, J. C. (2006). Clinical presentation of patients with tears of the acetabular labrum. Journal of Bone and Joint Surgery, 88(7), 1448e1457. http://dx.doi.org/10.2106/ jbjs.d.02806. Byrd, J. W. (2005). Physical examination. In J. W. Byrd (Ed.), Operative hip arthroscopy (2nd ed.). New York: Springer. Byrd, J. W. (2007). Evaluation of the hip: history and physical examination. North American Journal Of Sport Physical Therapy, 2(4), 231e240. Clarke, T. E., Cooper, L. B., Hamill, C. L., & Clark, D. E. (1985). The effect of varied stride rate upon shank deceleration in running. Journal of Sports Sciences, 3(1), 41e49. http://dx.doi.org/10.1080/02640418508729731. Clohisy, J. C., Knaus, E. R., Hunt, D. M., Lesher, J. M., Harris-Hayes, M., & Prather, H. (2009). Clinical presentation of patients with symptomatic anterior hip impingement [Research Support, N.I.H., Extramural] Clinical Orthopaedics and Related Research, 467(3), 638e644. Distefano, L. J., Blackburn, J. T., Marshall, S. W., & Padua, D. A. (2009). Gluteal muscle activation during common therapeutic exercises. Journal of Orthopaedic and Sports Physical Therapy, 39(7), 532e540. doi:2310 [pii] 10.2519/jospt.2009.2796. Domb, B. G., Brooks, A. G., & Byrd, J. W. (2009). Clinical examination of the hip joint in athletes. Journal of Sport Rehabilitation, 18(1), 3e23. Domb, B. G., Shindle, M. K., McArthur, B., Voos, J. E., Magennis, E. M., & Kelly, B. T. (2011). Iliopsoas impingement: a newly identified cause of labral pathology in

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