The diagnosis and treatment of hip pain in the young adult remains a challenge. Recently, understanding of a few specific hip conditions has improved; most notably femoroacetabular impingement. The differential diagnosis of hip pain has also expanded significantly, offering new challenges and opportunities. Along with the diagnostic dilemma, optimal treatment strategies for many conditions have yet to be proven and are current areas of important inquiry. This article reviews the current research on hip pain in the young adult and presents an overview of diagnostic and management strategies.
Key points
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Differential diagnosis of hip and groin pain.
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Nonoperative treatments of hip pain.
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Operative treatments of hip pain.
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Current concepts in management of femoroacetabular impingement.
Introduction
The management of hip pain in the young adult remains a challenge in some circumstances. Over the past few decades, understanding of a few specific conditions affecting the hip has advanced. Femoroacetabular impingement (FAI) is a condition that was popularized in recent decades. The optimal management of FAI and many other conditions affecting the hip is still unknown. The differential diagnosis of hip pain has also expanded, bringing with it new challenges and opportunities. The management of various causes affecting the labrum and cartilage of the hip joint are particularly problematic in the young patient, and evolution of the understanding of the young adult hip has dramatically changed management of this patient population. This article reviews the current literature on hip pain in young adults (ages 18–35 years), including physical and imaging diagnosis, the accepted treatments and controversies, and areas for further progress.
Evaluation of hip pain in the young adult
Clinical Presentation
A careful history and physical examination should be performed to appropriately elucidate the cause of the patient’s symptoms. The location of the pain is important because intra-articular hip pain most commonly presents in the groin but may also present on the side of the hip, in the buttock, and may refer to the anteromedial knee via the obturator nerve. Patients with FAI or other intra-articular pathologic condition may make a c-sign when describing their pain, grasping the hip in the c-shape. Buttock pain and pain radiating down the posterior leg should alert the practitioner to the possibility of pathologic state of the lumbar spine. Pain in the lateral aspect of the hip may indicate trochanteric bursitis or iliotibial band friction syndrome. Pain that is strictly medial may indicate adductor muscle disease or hernias. Pain that presents superior to the inguinal ligament and radiates to the groin can be a presentation of a sports hernia or intra-abdominal, urologic, or gynecologic disease. The description of the pain can point the practitioner in a particular direction. Dull ache with intermittent sharp symptoms can represent any number of pathologic states. However, shooting or electric pain with numbness or tingling is often neurologic in origin.
The onset and provocation of the pain can often lead the practitioner to an appropriate diagnosis. Traumatic events should be carefully investigated in terms of the position of the leg at the time of the event and force directed against it because this will give clues to the structures and muscles involved. Frank dislocation of the native hip can also result in the late sequelae of avascular necrosis. Pain with deep flexion is characteristic of labral tears or chondrolabral junction injuries. These can also present with external rotation and extension. Participation in certain sports activities has been associated with particular injuries. Labral tears are more common in patients who participate in hockey, football, gymnastics, soccer, ballet, running, yoga, and surfing. Runners are at high risk for iliotibial band friction syndrome and iliopsoas tendinitis. Mechanical symptoms indicate labral tears and chondral lesions. Painful clicking or snapping with flexion and extension is the presenting complaint of internal and external snapping hip (coxa saltans).
Medical History
Past medical history can give particular clues that should not be ignored, even in the young patient. A birth history indicating possible developmental dysplasia of the hip (DDH) should be elicited (even if the eventual diagnosis is made radiographically). First-borns, females, breech births, and oligohydramnios are the classic risk factors for DDH. It is important to know if patients had prior interventions for congenital hip dysplasia. A history of Legg-Calvé-Perthes or slipped capital femoral epiphysis may influence the choice of treatment and need for surgical intervention. A history of childhood obesity and endocrine disorders may raise suspicion for undiagnosed or subtle slipped capital femoral epiphysis. Any history with risk factors for avascular necrosis should be carefully teased out (eg, steroid use, alcohol, diving, human immunodeficiency virus infection [HIV], AIDS, antiretroviral therapy).
Physical Examination
The physical examination is a crucial portion of the diagnosis. The patient should first be observed ambulating. This exercise is most commonly done by watching the patient walk to the examination room before their knowledge of observation. Antalgic gait patterns should be observed carefully to help differentiate hip and knee disease. Knee or hip flexion contractures may also masquerade as antalgic gait. The practitioner should pay attention to foot progression angle as a clue for determining abnormal acetabular version. A Trendelenburg gait should be confirmed with the Trendelenburg sign and strength testing of the abductor muscles. Subtle abductor weakness can be present in patients with DDH. Abductor muscle weakness also increases the joint reactive force and may exacerbate problems that might not otherwise cause patient discomfort. The subtleties of abnormal gait may help in specific diagnoses but may also identify deficiencies and targets for specified therapy. Studies have shown that patients with symptomatic FAI have lower voluntary motor contraction in all hip muscle groups (adduction, abduction, flexion, internal and external rotation) as well as lower electromyography (EMG) activity in certain muscles such as the tensor fasciae latae. This can lead to specific kinematic and kinetic differences during gait. A study by Hunt and colleagues compared 30 subjects with symptomatic FAI scheduled for surgery with 30 control subjects without FAI. They found that the subjects with FAI had a slower walking speed with slower cadence. Kinematically, the FAI group exhibited significantly less peak hip extension, adduction, and internal rotation during stance. Physical therapy targeting specific deficits may have a role in the treatment of patients with FAI, or comparative kinematic measurements may have a role in determining the success of the operative therapy. However, this has not been formally studied.
The patient should be examined standing as well as supine. Leg-length differences should be noted and compared with radiographs (full-length films should be obtained if there is any equivocation). Range of motion should be carefully tested and compared with the asymptomatic leg. During testing, attention must be paid during hip flexion and extension to detect flexion contractures. This can be done by having the patient flex both knees to the chest and then extend 1 knee at the time, thus removing lumbar compensation. The Stinchfield test (resisted hip flexion with the leg straight and 6 inches off the table) can help diagnose intra-articular problems because it indirectly loads the joint via muscle contraction. There are several tests for impingement, including flexion abduction external rotation (FABER) and flexion adduction internal rotation (FADIR). The extreme of flexion alone may cause impingement and symptoms may also be reproduced with hip external rotation and extension. The FABER test may also be positive with sacroiliitis. However, the location of this pain is usually over the sacroiliac joint and not in the groin, buttock, or lateral hip as with FAI. The Ober test helps determine iliotibial band tightness. Clear points of tenderness that lead to specific diagnoses include the bursa over the greater trochanter and over the iliotibial band insertion on Gerdy tubercle. Tenderness in the groin may represent iliopsoas disease, a hernia, or simply an inflamed hip capsule. A straight leg raise eliciting pain in the buttock (ipsilateral or contralateral) or reproducing radiating pain down the leg is highly suspicious for lumbar disease. Nerve tension signs, muscle strength, sensation, and reflexes should all be tested.
Differential Diagnosis
A logical and systematic approach is helpful in developing a differential diagnosis for hip pain. There are several schemas that may be useful. One is differential diagnosis by process as seen in Table 1 . Another is differential diagnosis by anatomic location, as seen in Table 2 .
| Group | Possible Diagnoses | Common Presentations |
|---|---|---|
| Hip pain in the athlete | Muscle strains or tears, avulsions injuries, chondral or labral injuries, sports hernia | Often related to specific activities and movements or a single traumatic event |
| Congenital | Dysplasia | Insidious onset pain in the 2nd to 4th decade More common in females |
| Traumatic | Dislocation or subluxation, proximal femur fractures, chondral or labral injuries | Acute onset event |
| Vascular | Avascular necrosis | History of steroid use, alcohol, HIV Legg-Calvé-Perthes, leukemia, lymphoma, Gaucher, sickle cell, viral, lupus, hypercoagulable states, dysbaric disorders, irradiation, trauma |
| Metabolic | Transient osteoporosis | Middle-age men with no significant history, pregnant women |
| Inflammatory | Transient synovitis | Fever and groin pain relieved by NSAIDs Self-limited |
| Infection | Septic arthritis | Severe groin pain not relieved by NSAIDs |
| Impingement | FAI, labral tears | Pain with extremes of flexion, mechanical symptoms |
| Neoplastic | Synovial chondromatosis, PVNS | Groin pain and characteristic MRI appearance |
| Neurologic | Compression neuropathies and lumbar disease | Electric, shooting pain Pain in the buttock Numbness and tingling |
| Medications | As specific causes of AVN | Steroids, protease inhibitors |
| Intra-articular | Extra-articular Around the Hip | Pathologic Conditions Outside the Hip Joint |
|---|---|---|
| Labral tears | Trochanteric bursitis, Greater trochanteric pain syndrome | Lumbar radiculopathy |
| Chondral defects | Femoroischial impingement | Genitourinary (adnexa torsion, ectopic pregnancy, nephrolithiasis, orchitis, ovarian cysts, pelvic inflammatory disease, round ligament pain, round ligament torsion, urinary tract infection, endometriosis, prostatitis, testicular cancer) |
| FAI | Muscle injury (gluteal muscles, adductors, external rotators) | Intra-abdominal (abdominal aortic aneurysm, appendicitis, diverticulitis, lymphadenitis, diverticulosis, inflammatory bowel disease, inguinal or femoral hernia, tumors) |
| Capsular laxity | Piriformis syndrome | Sports hernia or athletic pubalgia |
| Ligamentum teres ruptures | Iliotibial band friction syndrome | Compression neuropathies (genitofemoral [L1, L2, L3], iliohypogastric [T12, L1], ilioinguinal [T12, L1], lateral femoral cutaneous [meralgia paresthetica], obturator, or pudendal) |
| Osteoarthritis | Iliopsoas tendinitis | |
| Inflammatory arthritis | Femoral stress fractures | |
| Osteonecrosis | Transient osteoporosis | |
| Loose bodies | Snapping hip (coxa saltans) | |
| Legg-Calvé-Perthes | Adductor strain | |
| Septic arthritis | Avulsion fractures | |
| SCFE | Iliofemoral ligament strain | |
| Synovitis | Sacroiliac injuries | |
| Instability | Pelvic stress fractures | |
| Synovial chondromatosis | Athletic pubalgia | |
| PVNS | Osteitis pubis | |
| Dysplasia | Psoas abscess |
Imaging
Imaging is of particular importance in reaching the correct diagnosis but certain pitfalls must be avoided. The correct interpretation of plain radiographs relies first and foremost on obtaining adequate films. Initial films include an anteroposterior (AP) pelvis with neutral rotation. When performed and interpreted adequately, this single view contains a wealth of information. The film should include the lower lumbar vertebrae as well as the proximal femora below the lesser trochanters. The practitioner should ensure that the film is neither an inlet nor an outlet view with the tip of the coccyx 3 to 4 cm from the pubic symphysis. On this view, the standard pelvic lines may be traced. A center-edge angle (CEA) and Tönnis angle can be calculated and crossover, posterior wall, and ischial spine signs observed for relative retroversion. The CEA of Wiberg ( Fig. 1 ) is the angle formed between the 2 lines passing through the center of the femoral head, 1 of which extends to the lateral edge of sourcil and a line perpendicular to a horizontal line joining the centers of the 2 femoral heads (of the 2 hips). The normal Wiberg angle in an adult is greater than 25°. The CEA greater than 40° is usually considered abnormal and may indicate pincer impingement. A CEA less than 25° indicates DDH. The Tönnis angle ( Fig. 2 ) is formed by the intersection of a horizontal line connecting the femoral head centers and the line that passes through medial edge of the sourcil to its lateral edge. An angle of less than 0° may indicate impingement and an angle of greater than 10° may indicate dysplasia or instability. The crossover sign indicates acetabular retroversion and is determined when the shadow of the anterior wall crosses the shadow of the posterior wall. A hip with a normal pelvic inclination should have the anterior and posterior rims join at the edge of the acetabulum. A positive crossover sign is often accompanied by an ischial spine sign in which the ischial spine protrudes beyond the ilioischial line into the pelvis and is prominent. The posterior wall sign is positive when the posterior wall is medial to the center of the femoral head and also indicates retroversion. Superior migration and extrusion of the femoral head are also notable signs of dysplasia and subtle changes can be detected by a break in Shenton line. The practitioner should look for signs of coxa profunda (fossa acetabuli touches or is medial to the ilioischial line) and protrusion acetabula (medial aspect of femoral head is medial to ilioischial line). A cross-table lateral is unreliable in determining acetabular version and the reader may also miss head-neck offset abnormalities. A frog-leg lateral may be useful in elucidating proximal femoral disease. A Dunn lateral view (flexion-abduction) is often used to better appreciate a cam lesion. The faux profile view can aid in evaluation of anterior coverage of the femoral head. On this view one can measure the anterior CEA in a similar fashion to measuring the lateral CEA on the AP radiograph. An anterior CEA less than 20° indicates a deficient anterior wall.
