Anterior and medial hip disorders affecting athletes’ hip include dysfunction and/or pain affecting the anteromedial structures of the hip. These problems may be approached with “The Layer Concept,” a classification system that best determines the primary pain generator.1 The 4 layers include osseous (bone), inert (capsule/labrum), contractile (muscles/tendons), and neuromechanical (referred pain from peripheral neurovascular structures and spine).
Etiologies of anteromedial hip disorders may range from intraarticular to extraarticular disorders. These include direct injury to the labrum, capsule or tendon, or problems secondary to bony abnormalities such as femoroacetabular impingement (FAI), which can affect the labrum, cartilage, and capsule. FAI is an anatomical abnormality at the femoral head neck junction or acetabular rim, where range of motion of the joint leads to impact at these two regions. Extra-articular impingement seen in this region includes sub-spine (anterior inferior iliac spine (AIIS) impingement. Acute and chronic musculotendinous overuse injuries of the anterior and medial regions, especially affecting the hip flexors and adductors are other common disorders affecting this unique patient population. Stress reactions and fractures of the femoral neck and pelvis are another group of repetitive overuse disorders in the setting of altered bone turnover may be the cause of anteromedial pain in athletes.31,32 Compression neuropathies, such as ilioinguinal, genitofemoral, or obturator neuropathies and referred pain from disorders of the spine or pelvic floor, are other potential etiologies.2,3
Epidemiology including risk factors and primary prevention
Although there is no known published data on the overall incidence and prevalence of all anteromedial hip disorders in the general population, there is, however, data regarding athletes and sports related hip pain. Studies have shown that groin related injuries in sports with rapid directional changes, kicking, and twisting, such as in ice hockey, soccer, and rugby, account for 5-18 % of injuries.4,5,62,65 Position played also plays a role in the type of injury that may occur. For example, ice hockey goaltenders may be more prone to intraarticular hip injuries than other positions. 66e specifically, labral injuries have been reported in these aforementioned sports and also in golfers, rowers, dancers, karate practitioners, basketball, and baseball players.4-8 According to Epstein et al’s 2012 retrospective study of NHL players, the “cumulative incidence rate of [both hip and groin injuries was] 19.87 injuries per 100 players per year.9,10 In Feeley et al’s 2008 study of the NFL from 1997 to 2006, muscle strains (most common hip flexor), hip contusions, and intra-articular injuries (labral tears, fractures, and dislocations/subluxations) made up 59, 33, and 5% of all NFL injuries, respectively. Although representing only 5% of all injuries, intra-articular hip injuries accounted for the most time lost.4 All of these sports are prone to these type of injuries given the high mechanical stresses and loads placed on the joint, combined with motions such as cutting and extremes of hip flexion and internal rotation.2-4,11
In regards to Cam impingement, there is data to suggest that cutting sports (soccer, basketball, hockey), particularly during the growth years, may lead to increased Cam type deformities and impingment.5,12-14 With studies showing up to 68% of Cam type deformity in young male athletes.68Thus, it is important that younger pre-adolescent athletes participating in sports such as soccer or basketball be educated on avoiding extreme flexion, deep squats, and lunges to prevent the development of such femoroacetabular abnormalities at the time of skeletal maturity. 5,12-14 For young athletes participating in sports such as baseball, other recommendations to prevent these abnormalities include rotating playing positions on the field.
Risk factors for the most common anteromedial hip disorders are listed below:
- Intra-articular hip osteoarthritis: include FAI, obesity, and advancing age15,16
- Stress reaction or stress fractures: include tobacco or alcohol use, osteopenia/osteoporosis, female athlete triad, female military recruits, endurance sports such as track and field, skaters 31,32
- Labral tears: female sex, history of Legg-Calve-Perthe’s disease; developmental hip dysplasia, instability, decreased femoral or acetabular version, decreased head-neck offset2,17
- FAI: labral tear, developmental hip dysplasia, age, cutting sports (basketball, soccer, football); young, active males-cam lesions, middle age females-pincer lesions17-20
- Athletic pubalgia or Core muscle injury: increased among football, hockey, soccer, and tennis players2,21,22
- Iliopsoas impingement and coxa saltans (also known as internal snapping syndrome): increased among ballet dancers and patients with rheumatoid arthritis2,7,23
- Sub-spine (AIIS) impingement: prior AIIS avulsion injury, acetabular overcoverage and femoral retroversion2,17
Different mechanisms will be outlined for the most common diagnoses seen:
- Osteoarthritis (osteochondral layer): occurs due to abnormal joint mechanics and loading, which leads to decreased joint space narrowing, bony sclerosis, and articular cartilage loss. FAI, labral tears, hip dysplasia, and acetabular retroversion are proposed to be precursors to this non-inflammatory process, especially in younger patients before the age of 55. 15,16,24,25
- FAI (osteochondral layer): anatomical abnormality at the femoral head neck junction or acetabular rim with range of motion of the hip leads to impingement.
–Cam type impingement is caused by an abnormal shaped femoral head or neck contacting the acetabular rim during flexion and internal rotation activities. The anterosuperior acetabular cartilage is most affected. 18,19,24-26
–Pincer type impingement is caused by overcoverage of the acetabulum over the femoral head. Repeated contact leads to circumferential cartilage damage, but also posteroinferior labral degeneration (from contra-coup mechanism) and acetabular deepening.18,19,24-26
- Labral tears (inert layer): According to one model from McCarthy et al., labral damage results from repeated impingement due to FAI and/or stress on the joint from developmental hip dysplasia at extreme ranges of motion. Articular cartilage damage is part of and contributes to this process if delamination of the articular cartilage occurs.27-30
- Rectus femoris or iliopsoas tendinopathy (contractile layer): results from improper training, repetitive loading, or trauma.2,3,23
- Iliopsoas impingement (contractile layer): Psoas tendon snaps over the iliacus as the hip moves from flexion, abduction, and external rotation to extension and internal rotation. Dynamic ultrasound studies have demonstrated that the psoas tendon glides over the medial part of the iliacus and the superior pubic ramus during the return of the hip into a neutral position.3,23
- Athletic pubalgia or core muscle injury (contractile layer): no actual hernia exists, but shearing forces placed across the pubic symphysis from the adductors, rectus abdominae, and stresses of the inguinal wall musculature may predispose athletes to unilateral groin pain.2,21,22
- L1 or L2 radiculopathies or obturator neuropathy (neuromechanical): compression of spinal nerve root and peripheral nerve secondary to commonly, a disc herniation or local trauma, respectively.2,17,30
- Ischiofemoral impingement: narrowing of space between the lesser trochanter and ischial tuberosity that leads to the compression of the quadratus femoris muscle. This may lead to pain in groin area that increases with weight bearing.68,69
Disease progression including natural history, disease phases or stages, disease trajectory (clinical features and presentation over time)
Acute muscle strains tend to resolve with basic conservative care (relative rest, ice, compression, and elevation), whereas tendinopathies may continue to progress to chronic phases without proper eccentric strengthening programs. With hip osteoarthritis, progression is seen with further decreases in joint space, increased osteophyte formation, and bony sclerosis (severity may be graded with the Tonnis grading scale), though this may not always correlate clinically with increased pain or decreased function.15,16 Injuries resulting from untreated stress fractures tend to be more symptomatic at initial onset, but may resolve quickly and only be reproduced with specific activities. However, in the case of femoral neck stress fractures, compression sided fractures should be worked up and monitored with limited weight bearing to start, whereas tension sided stress fractures should be immediately evaluated by an orthopedic surgeon due to an increased risk of fracture and displacement.31,32
Specific secondary or associated conditions and complications
FAI and labral tears may increase the risk for the development of early hip osteoarthritis.2,15,18,19 Associated conditions may include hip abductor dysfunction, chronic lower back pain, and poor flexibility in the quadriceps, hamstring, and tensor fasciae latae and iliotibial band tendons.2,17,21 Biomechanical changes in the hip may lead to the development of lumbar pathology, otherwise known as a secondary hip-spine syndrome.79
2. ESSENTIALS OF ASSESSMENT
A comprehensive history should include onset and duration of symptoms, quality and character of pain or dysfunction, location, radiating symptoms, exacerbating and alleviating factors, whether the disorder is affecting the athlete’s sport participation or performance, education (if in school), and functional activities. A past history of similar injuries, nutrition, and menses history (for females) are also relevant details.
The physical exam should be carried out in 4 different positions (standing, sitting, supine, and prone). The standing exam assesses for “general body habitus, gait, lumbopelvic alignment, ligamentous laxity, and Trendelenberg testing for functional hip abductor weakness. The seated exam checks for any abnormalities in skin, vasculature, and lymph, while hip internal and external range of motion can be examined in this position.”33 In addition, this is a good position for the neurologic examination. Here, both lower extremity sensory testing with light touch and pinprick, reflexes, and dural tension testing in the form of the Seated Slump test are assessed.
The supine position is the most important, where complete passive range of motion, manual muscle strength, and provocative testing may be performed. Provocative maneuvers such as FADIR (hip flexion, adduction, internal rotation), FABER (flexion, abduction, external rotation), sub-spine impingement (straight hip flexion), Thomas test (to assess for iliopsoas tightness), and both passive and resisted straight leg tests may be used additionally to help narrow the differential diagnosis and determine what structures would need targeted therapy.17,33,34 In the side-lying position, passive adduction maneuvers can be performed to assess for contractures of the tensor fascia latae, gluteus medius, and gluteus maximus. Hip abductor strength should be tested in slight extension and internal rotation of the femur to prevent iliotibial band and tensor fasciae latae compensation. Lastly, the prone exam is used to assess the posterior hip structures such as the hamstrings and to assess for femoral version. At each position, the examiner should palpate the anteromedial structures of interest (ie: pubic symphysis, ASIS, AIIS, rectus femoris, adductors) , as well as lower lumbar paraspinals and posterolateral hip structures such as the greater trochanter, tensor fasciae latae, and posterior superior iliac spine (PSIS) to rule out referred pain sources.33
Functional testing can be performed to dynamically evaluate range of motion, strength, and proprioception. Importantly, this assessment includes evaluation in all three planes of motion (ie: frontal, sagittal, and transverse). Two of the most common forms of functional testing include the single leg squat (SLS) and step-down tests (SDT). In the SLS test, the patient is standing with the contralateral knee flexed. The patient then attempts to perform a squat on the ipsilateral lower extremity. In the SDT, the patient stands on a stool with the contralateral hip slightly flexed and the knee in extension. The patient then attempts to lower the contralateral foot to the floor in a controlled fashion. This form of assessment may reveal kinematic and biomechanical deficiencies not otherwise evident in traditional, static evaluations.70
Clinical functional assessment: mobility, self care cognition/behavior/affective state
Although this varies from disorder to disorder, activities such as transitional movements, walking, stair climbing, and deep squats are the most commonly reported to be aggravated with most anteromedial hip disorders. Alternative modes of exercise such as a stationary bike or switching to a cross-training program may be necessary while an injured athlete undergoes a specific lower extremity rehabilitation program.
No laboratory studies are routinely required unless an infectious or rheumatologic etiology is suspected. In such cases, a basic cell blood count may show leukocytosis with elevated inflammatory markers (eg: erythrocyte sedimentation and C-reactive protein levels). Inflammatory or infectious disorders of the pelvis may need to be ruled out in unusual cases. A full rheumatologic panel may be ordered if necessary.
Initial work-up should include plain films of the hip (AP, elongated femoral neck), as well as the lumbar spine to rule out an overlapping spine disorder.17,35 MRI of the hip may be ordered if there is suspicion for a symptomatic labral tear or to assess for a specific tendon or muscle tear (eg: rectus femoris), or fracture.36,37 MR arthrography (MRA) is considered the best imaging modality to assess for labral tears, but this is debated.36-38 The costs vs benefits of such a study may also need to be determined.64
Musculoskeletal ultrasound has proved to be useful for both diagnostic and interventional purposes.39 Sonopalpation may help diagnose and reveal the location of an injury if pressure at a specific location reproduces the patient’s pain.62 This may be useful for planning injection procedures. Ultrasound can help correlate findings in real time and attain dynamic images in various positions, including valsalva in the evaluation of athletic pubalgia. This also gives the physician increased patient interaction.63 Iliopsoas impingement, bursitis, tendinopathies, and intra-articular hip effusions may be visualized using this dynamic, real-time imaging modality.39,40 It should be noted, however, that ultrasound alone does not adequately image the hip joint itself or the cartilaginous labrum, compared to MRI.
Supplemental assessment tools
Existing hip research tools have primarily focused on patients with hip fractures or arthritis such as the Harris Hip Scores. The most common measure used is the Modified Harris Hip Score. The Multicenter Arthroscopy of the Hip Outcomes Research Network (MAHORN) group developed a 33 question survey tool that was applicable to a number of common bony or labral hip pathologies.41 However, it is not applicable to muscular or referred pain from spine or knee sources. The Hip Outcome Score (HOS) has been validated for hip labral injuries.42 Other outcome measures include the Western Ontario and McMaster University Osteoarthritis Index (WOMAC), Short Form-36, Hip Disability and Osteoarthritis Outcome Score (HOOS), Non-Arthritic Hip Score (NAHS), and the Copenhagen Hip and Groin Outcome Score (HAGOS).41-45
Early prediction of outcomes
There are factors which may help predict a positive outcome in patients with anteromedial hip sports-related injury. For example, patients with an acetabular labral tear without hip OA are more likely to have a positive outcome.29 As with the management of other musculoskeletal conditions, the principles of close follow-up, compliance with prescribed treatment, and a solid, physical therapy program will generally alleviate and improve patient’s symptoms stemming from anteromedial hip pain.
For patients who require operative management, younger age, female sex, hip dysplasia, instability, and residual intra-and extra-articular impingement were identified as risk factors for revision arthroscopic or open hip preservation surgery in a cross sectional study of 147 patients.61
Environmental factors include whether the sport is played indoor or outdoor, the type of surface or terrain, and any related clothing, equipment, or gear that is used. Hip motion, especially, extremes of flexion and internal rotation, can affect the condition of the hip. Athletes should be counseled on modifying these environmental factors in the management of their hip conditions. Reducing training during growth years, cross training, or adding orthotics to patients with pes planus may be considered.
Social role and social support system
When athletes or patients are not actively engaging in their preferred sport or exercise, depressive or anxious symptoms may arise. Thus, it is important to educate and counsel athletes, families, and personal trainers/coaches regarding alternative sports and exercises they may safely participate in, while they are being treated.
Education and open communication with the athlete’s family, friends, athletic trainers, and coaches is necessary to prevent recurrent injury and to maintain effective physician-team rapport. Special precautions must be taken with college or professional athletes, as there may be a financial incentive or institutional pressure to have the athlete return to play before he or she is ready to. In such cases, emphasis must be placed on the athlete’s health and safety before team commitments.
3. REHABILITATION MANAGEMENT AND TREATMENTS
Available or current treatment guidelines
There are no available consensus statements or treatment guidelines for most of the disorders discussed above. There is, however, an abundance of literature to support the surgical management of certain conditions including FAI and labral tears. Unfortunately, there are no double blinded, randomized controlled trials comparing the efficacy of physical therapy and conservative care versus surgical intervention in the treatment of these and other anteromedial hip disorders.46 Although surgical studies do promote the use of activity modification and physical therapy as the initial treatment, there is no agreed upon “best practice” when treating athletes with anteromedial hip pain and dysfunction.4,17,46-50
Conservative treatment usually involves rest, NSAIDs, heat and/or ice. In FAI, as well as the other anteromedial hip disorders discussed above, rehabilitation efforts should focus on core muscle strengthening, and treating the imbalance between the hip and abdominal muscles. Improving range of motion of the hip external rotation and abduction in extension and flexion has shown to be beneficial.66,78
Treatment for osteitis pubis also begins with conservative management focusing on physical therapy. A recent study evaluated the use of shock wave therapy versus sham shock wave therapy directly to the pubis and reported promising results with earlier return to sport with the use of shock wave therapy.67
In ischiofemoral impingement, the reduced space between the lesser trochanter and ischial tuberosity may cause a leg length discrepancy. Conservative management with the use of insoles or shoe modifications have been proposed as.68 For the treatment and management of athletic pubalgia, a position statement was put forth by the British Hernia Society in 2014.50 They advised at least a 2 month program consisting of active, supervised physical therapy emphasizing core and lumbopelvic stabilization and strengthening (initially isometric then progressing to eccentric and concentric) exercises, cross training, and appropriate injections (not specific, but ilioinguinal nerve blocks were cited) prior to any surgical consultation.51 There is a current push in the United States to describe this condition as a core muscle injury.52
With respect to return to play, assessing the athlete’s level of pain and its effect on functional activities is important.32 General treatment includes a thorough work up of risk factors and treatment followed by relative rest, activity modification, and weight bearing precaution, with activity titrated using pain as a guide during an average period of 4 to 8 weeks depending on the severity of the stress fracture.32 While the stress fracture is allowed to heal, athletes should be encouraged to cross train such as swimming, cycling, or aqua-running, counseled on nutrition, and to be screened for low bone mineral density.32 Athletes who have pain from FAI and labral injuries may improve with a focused rehabilitation program that avoids motions that aggravate and reproduce symptoms.
At different disease stages
In the acute to subacute setting, anteromedial hip disorders may be approached with activity modification (eg: avoidance of deep hip flexion and internal rotation to prevent impingement symptoms), rest for a limited time away from the sport, modalities such as ice or heat, a short course of oral anti-inflammatory medications, and an emphasis on an appropriate physical therapy and home exercise program.4,18,19
Most patients with anteromedial hip dysfunction (especially FAI) will have weakness with hip adduction, abduction, flexion, [and/or] external rotation, as well as have disturbances with core trunk and lumbopelvic stability and control.4,17,21,46 Hence, the physical therapy prescription should address such strength deficits found on physical exam, accompanied with the goal of improving their lumbopelvic range of motion, proprioceptive training, and reducing pain during sport-specific functional tasks.17 It is very important to include both hip and spine stability exercises before the patient is progressed to sport specific training.17,21,53
If patients do not improve with non-operative management, then their diagnosis should be reconsidered and further work-up done as necessary. On the other hand, they are unable to advance their rehabilitation program because of pain, other conservative treatments are available. For intra-articular lesions (osteochondral or inert layer disorders) such as hip osteoarthritis, FAI, or labral tears, an image guided intra-articular hip injection consisting of a combination of local anesthetic with or without corticosteroid may be used both diagnostically and therapeutically to alleviate pain and help the athlete continue in physical therapy or return to play sooner. They also appear to hold a prognostic value in predicting the need for surgical interventions.2,4 Extra-articular or contractile layer disorders (eg: psoas impingement syndrome) may similarly benefit from an image-guided bursa or tendon sheath injection. Initial injections may be performed with local anesthetic and corticosteroid, but may be transitioned to more novel treatments such as platelet rich plasma (PRP) (with or without percutaneous needle tenotomy) if the underlying dysfunction is due to tendinopathy, keeping in mind that PRP is still considered experiemental.3,54-57
Chronic disorders can be managed similarly, but often require a longer recovery process. In chronic intra-articular conditions secondary to hip osteoarthritis, ultrasound guided viscosupplementation injections, although not yet approved for hip OA by the Food and Drug Administration, may be used and preferred over repeat corticosteroid injections.58-60
Coordination of care
It is crucial that a multidisciplinary team approach involving the patient’s physician(s), family, athletic trainers, coaches, and physical therapists is used to maximize healing before returning to play. It is important that communication remains consistent and that the athlete’s diagnosis(es) are always kept in mind.
Patient & family education
As discussed earlier, proper education regarding an athlete’s diagnosis, available treatment options, prognosis, injury prevention, and expected return to play should be communicated to both the athlete and his or her family. In addition, at follow up visits or in the training room, gentle reminders should also be used to reinforce avoidance of specific lower extremity motions and the maintenance of a home exercise program to prevent re-injury.
Measurement of Treatment Outcomes including those that are impairment-based, activity participation-based and environmentally-based
Besides monitoring the severity and frequency of pain, efficacy of conservative treatment is based on a number of factors such as improvements in core and pelvic girdle muscle weakness, lumbopelvic range of motion, and the ability to perform sport specific tasks with minimal discomfort.
Translation into Practice: practice “pearls”/performance improvement in practice (PIPs)/changes in clinical practice behaviors and skills
Providers should keep in mind to examine both the spine and knee, as pain patterns at the anteromedial hip may be referred. Initial work-up may include imaging of such regions depending upon patient presentation.
Incorporate functional tests, such as the SLS and SDT, into your physical examination for dynamic evaluation of range of motion, strength, and proprioception.
The core encompasses the lumbar spine through the thighs. The iliopsoas is the only muscle that has its origin in the spine and crosses the hip joint. It works both as a spine stabilizer and hip flexor. All of these elements must be addressed to return athletes to sport.
Focused hip flexor concentric strengthening can exacerbate symptoms. Focus on strengthening the abductors and core stability. Eccentric and isometric exercises can be initiated as the pain subsides.
Femoral neck stress fractures can mimic hip impingement. Always keep it in mind when a patient with risk factors for a stress fracture has multiple impingement signs encountered on physical exam.
If pelvic floor dysfunction/pain is part of the differential diagnosis, a more detailed social history should be elicited including any history of physical or sexual abuse, as well as any past psychiatric illness.
4. GAPS IN THE EVIDENCE-BASED KNOWLEDGE
The current medical literature does not contain any double blinded, randomized controlled studies assessing the benefits of a structured rehabilitation program versus surgical intervention for patients or athletes with anteromedial hip disorders.46 There is also no data as to whether structured rehabilitation programs modify the natural history of degenerative joint changes found in symptomatic FAI.18
Regenerative medicine procedures, such as PRP or stem cell injections, have the potential for both pain relief and healing of damaged tissue.58-60,71-75 More high-quality research is required, including comparing these injections to other physical and pain-relieving modalities, surgery and the need for long-term follow up.
5. CUTTING EDGE/EMERGING AND UNIQUE CONCEPTS AND PRACTICE
The use of musculoskeletal ultrasound to assess for dynamic impingement, tendinosis, and for guidance of interventional procedures has shown promise as part of the spectrum of conservative management of patients and athletes who decline surgery or are not ideal surgical candidates. 39
In addition, PRP injections may be beneficial for improving pain from rectus femoris or iliopsoas tendinopathies and potentially for intra-articular conditions such as hip osteoarthritis, when combined with a supervised rehabilitation program.39,58-60
In addition to evidence for the clinical benefit of PRP in OA,58-60,71 there is also evidence that it may help in the treatment of acetabular labral tears76 and, when, combined with bone marrow- derived mesenchymal stem cells, in osteonecrosis of the hip74. Stem cell injections on their own may be clinically effective not only in OA72,73, but also in osteonecrosis of the hip.75,77
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Original Version of the Topic
Peter J. Moley, MD, Richard G. Chang MD, MPH. Sports medicine disorders of the hip: Anterior-Medial. 09/16/2015.
Timothy Tiu, MD, FAAPMR, CAQSM
Nothing to Disclose
Natalia Miranda-Cantellops, MD
Nothing to Disclose