Overview of Pathologies
A solid understanding of the differential diagnosis for hip pathology is necessary before collecting a history and performing a physical examination. This background allows the clinician to tease out important elements in the history to narrow the differential and provide a focus for the physical examination. An overview of hip pathology is presented in the following sections ( Box 80-1 ).
S oft T issue I njuries
Bursitis
Trochanteric
Ischial
Iliopsoas
Iliopectineal
Snapping hip syndrome
Contusions
Iliac crest
Quadriceps
Groin
Myositis ossificans
Strains
Adductor
Iliopsoas
External oblique
Hamstring
Quadriceps
Sacroiliac sprain
Hernias
Inguinal
Femoral
Sports (athletic pubalgia)
B one I njuries
Traumatic fractures
Dislocation
Stress fractures
Pelvic
Sacral
Femoral neck
Osteitis pubis
Osteonecrosis
D egenerative J oint D isease
N erve E ntrapment I njuries
Sciatic
Obturator
Pudendal
Ilioinguinal
Femoral
Lateral femoral cutaneous
I ntraarticular P athology
Labral tears
Femoral acetabular impingement
Loose bodies
Chondral injuries
Ruptured ligamentum teres
I nfection
P ediatric C onditions
Avulsion fracture
SCFE
Legg-Calvé-Perthes disease
SCFE, Slipped capital femoral epiphysis.
Soft Tissue Injuries
Inflammation and pain originating from the trochanteric, ischial, iliopsoas, and iliopectineal bursae are common. Movement at bone and soft tissue interfaces leads to repetitive friction and inflammation in these areas. Trochanteric bursitis is very common. Patients describe lateral thigh pain that can be reproduced with palpation on examination. Ischial bursitis typically presents with pain upon sitting and can be reproduced by palpation over the ischial tuberosity. The iliopsoas bursa lies between the iliopsoas muscle and pelvic brim. Patients typically present with inguinal pain that is reproducible with provocative maneuvers such as the Thomas test. The iliopectineal bursa is adjacent to the iliopsoas bursa but lies over the iliopectineal eminence. Symptoms are similar to those of iliopsoas bursitis, although iliopectineal bursitis can be seen in conjunction with a snapping iliopsoas muscle over the iliopectineal eminence.
Snapping hip syndrome, also referred to as coxa saltans , causes an audible or palpable “snap” with hip range of motion (ROM). The etiology of a snapping hip is classified as external, internal, or intraarticular. An external snapping hip is caused by the iliotibial band gliding over the greater trochanter. An internal snapping hip is attributed to shifting of the iliopsoas tendon from medial to lateral over the femoral head, or iliopectineal eminence, during hip flexion and extension. An intraarticular snapping hip is related to labral tears, loose bodies, or osteochondral injuries.
Contusions involving the hip, thigh, and pelvis are frequently encountered in athletes and occur after low-energy trauma. An iliac crest contusion, or “hip pointer,” results from a direct blow to the iliac crest, and an overlying hematoma often develops. Quadriceps contusions typically involve a direct blow to the anterior thigh, which can result in hematoma formation and difficulty ambulating. A direct blow to the inner thigh may result in a groin contusion. Myositis ossificans often occurs after a contusion and hematoma. The hematoma organizes and calcifies, which can lead to pain and stiffness. Myositis ossificans can also be seen in the absence of trauma.
Muscle strains and ligamentous injuries in the area of the hip can be quite debilitating. Strains typically involve tearing at the musculotendinous junction and often occur during an eccentric contraction. Strains are classified by the affected muscle groups, including adductor, iliopsoas, external oblique, hamstring, and quadriceps. With significant force during athletics, or in the setting of trauma, the strong sacroiliac ligaments can be sprained. Pain typically originates in the lower back and radiates into the buttock or groin.
Hernias involve the extrusion of abdominal contents through a defect in the abdominal wall. A delay in diagnosis is common because hernias can mimic other conditions that cause groin pain with activity. Three hernias can present as hip or pelvic pain: inguinal, femoral, and sports hernias. Inguinal hernias involve the protrusion of abdominal contents through the deep inguinal ring or medial to the deep inguinal ring. Femoral hernias occur when a hernia sac protrudes through the femoral sheath to enter the anterior thigh. The sports hernia is an increasingly recognized condition causing groin pain in athletes. The pathophysiology is incompletely understood, but it appears to involve weakness or tearing of the posterior inguinal wall. No true protrusion of abdominal contents occurs, but patients experience chronic groin pain that is often difficult to diagnose.
Bone Injuries
Trauma during sporting events can result in fractures of the pelvis and femur. Pelvic ring injuries, acetabular fractures, femoral head and neck fractures, peritrochanteric fractures, and femoral shaft fractures lead to the acute onset of pain and difficulty with mobilization. Prompt recognition and treatment of the bony injury and soft tissue trauma is critical. Hip dislocations also occur when significant force disrupts the soft tissue restraints of the hip joint. Hip dislocations are typically posterior, which leads to the patient having a shortened, internally rotated, and abducted hip. Less commonly, the dislocation will be anterior, which presents as an externally rotated and abducted hip. Expeditious recognition and reduction may be essential to prevent avascular necrosis.
Stress fractures of the pelvis and femur occur in the setting of repetitive submaximal loading of bone. Pain that is aggravated by activity and subsides with rest is the hallmark feature of a stress fracture. Pelvic rami and sacral stress fractures are seen in athletes who participate in high-impact activities such as running and jogging. The pain is typically in the groin, buttock, or thigh when the ramus is involved and in the low back when the sacrum is the source. Femoral neck stress fractures typically present with activity-related groin pain. The location of the stress fracture is critical to determining treatment. Tension-sided femoral neck stress fractures along the superior lateral neck require surgical treatment to prevent nonunion, avascular necrosis, or fracture displacement. Compression-sided femoral neck stress fractures occur along the inferior medial neck and are often amenable to nonoperative treatment.
Inflammation of the pubic symphysis is termed “osteitis pubis.” Overuse of hip adductors and the gracilis may lead to this condition. The pain is typically insidious in onset and midline over the symphysis.
Osteonecrosis, or avascular necrosis, of the femoral head is a cause of hip pain in young adults. Many conditions have been associated with osteonecrosis; however, the majority are related to corticosteroid use, trauma, alcohol abuse, and coagulopathy. No cause is identified in 10% to 20% of cases, and this type of necrosis is termed “idiopathic avascular necrosis.” Patients typically present with pain in the groin or buttock and often walk with a limp. Bilateral avascular necrosis has been found in 40% to 80% of patients. Early identification may allow treatment that can prevent femoral head collapse and the need for arthroplasty.
Degenerative Joint Disease
Degenerative joint disease (DJD) results from the loss of cartilage in the hip joint and leads to progressive pain and stiffness. Although the process may be idiopathic, we now recognize that structural abnormalities of the hip are frequently associated with DJD. The diagnosis is usually confirmed by observing joint space narrowing on plain radiographs. Patients typically present with the insidious onset of hip pain that worsens with activity.
Nerve Entrapment Injuries
Nerve entrapment surrounding the hip can involve the sciatic, obturator, pudendal, ilioinguinal, femoral, and lateral femoral cutaneous nerve. Diagnosing and treating these conditions can be difficult and frustrating for the patient and clinician. The pain often has a burning quality and is confined to a nerve root distribution. Electromyographic and nerve conduction studies are helpful in confirming the diagnosis and ruling out a lumbar radiculopathy. Sciatic nerve entrapment often presents with pain radiating down the buttock and posterior thigh. In some cases, this pain may be related to piriformis syndrome. Obturator nerve entrapment causes pain in the medial thigh that can radiate toward the knee. Prolonged compression during activities such as cycling can cause pudendal nerve entrapment. Numbness and pain in the perineum and shaft of the penis are typical. Ilioinguinal nerve entrapment is a cause of inguinal pain that often radiates into the groin. Pain over the anterior thigh can be caused by femoral nerve entrapment, and when severe, it may cause quadriceps weakness and difficulty with gait. Lateral femoral cutaneous nerve entrapment, or meralgia paresthetica , causes anterolateral thigh pain and numbness that extends toward the lateral knee.
Intraarticular Pathology
Our understanding of intraarticular pathology has significantly expanded during the past few decades. Structural abnormalities of the hip joint seen in persons with dysplasia and femoroacetabular impingement often lead to injury of the labrum and chondral surface. Hip dysplasia, or developmental dysplasia of the hip, results in a broad spectrum of disease. The underlying abnormality is inadequate coverage of the femoral head, which in severe forms can cause hip dislocations in children. Often the degree of undercoverage is mild and leads to pathology during adulthood because of the concentration of forces on a shallow acetabulum. Femoroacetabular impingement is caused by abnormalities of the femur and acetabulum that lead to abnormal contact within the hip joint. Deformity on the femoral side is termed cam impingement and is due to an out-of-round femoral head. Deformity on the acetabular side is termed pincer impingement and occurs when the acetabulum is too deep. Frequently both abnormalities exist in the same hip joint, and this condition is termed combined impingement . The iliopsoas muscle can also cause direct anterior impingement. Patients with intraarticular pathology typically present with groin or buttock pain. Scrutinizing hip radiographs will often help the clinician identify morphologic abnormalities of the hip that may lead to intraarticular pathology. Multiple other sources of intraarticular pathology have also been described, such as ruptured ligamentum teres, loose bodies, and synovial disease.
Infection
Septic arthritis of the hip should always be considered in a patient who presents with the acute onset of pain. The patient is often febrile and lacks a history of trauma. Physical examination reveals pain with attempted passive ROM. Inflammatory markers are typically elevated. Prompt recognition and treatment are necessary to prevent long-term complications.
Pediatric Hip Conditions
Skeletally immature patients often present with hip conditions that differ from the hip conditions of adults. Open physes and apophyses are areas of weakness and are frequently injured. When muscles are overloaded in children, failure can occur at the origin of the muscle, particularly when an apophysis is present. This scenario causes an avulsion fracture at the muscle origin, which differs from the pathology seen in adults, who most frequently experience a fracture at the musculotendinous junction. Avulsion fractures occur at the anterior superior iliac spine, anterior inferior iliac spine, ischial tuberosity, and lesser trochanter when the sartorius, rectus femoris, hamstrings, and iliopsoas muscles, respectively, are overloaded.
Slipped capital femoral epiphysis (SCFE) is a disorder of the proximal femoral physis. The proximal femoral physis fails, leading to anterior superior displacement of the femur relative to the epiphysis. This condition typically involves patients 11 to 14 years of age and often affects obese children. Displacement at the physis can frequently be identified with a frog-leg lateral radiograph. When SCFE is identified, surgical treatment is typically indicated.
Legg-Calvé-Perthes disease is a childhood disorder that leads to ischemic necrosis of the growing femoral head. The process typically affects patients 5 to 8 years of age and predominantly involves boys. Parents notice that the child is limping, and the patient often has mild pain. Radiographs often identify abnormalities in the femoral epiphysis.
History
Evaluation of the hip should begin with a thorough history, including several standard components. The goal of the history should be to (1) rule out any alarming sources of hip pathology, including cancer, infection, or systemic disease; (2) begin to differentiate true hip pain from back pain, which can often be confused ; and (3) narrow the differential diagnosis to perform a focused physical examination. The clinician should ascertain the patient’s age and profession, the chief complaint, the presence or absence of trauma, and any treatment modalities the patient may already have attempted to use. These modalities often include nonsteroidal antiinflammatory medications, assistive devices, interaction with other physicians, or physical therapy. If the patient has experienced a recent trauma, a detailed history of that trauma should be elicited. A history of acute onset or trauma is a better prognostic indicator than an insidious onset of symptoms. A detailed pain history includes the location, intensity, quality, onset, duration, alleviating factors, aggravating factors, and associated factors ( Fig. 80-1 ). The clinician also should inquire about the presence of mechanical symptoms such as popping, locking, clicking, subjective instability, pain that is worse with activity, or pain that is worse with twisting maneuvers. Pain or catching during flexion and axial loading activities (e.g., rising from a seated position, walking up or down stairs, or entering and exiting a vehicle) also implies mechanical hip pain. Patients also report pain with sexual intercourse or difficulty putting on shoes or socks because of rotational force and complex hip movements.
The remainder of the standard history should not be overlooked. A medical and surgical history may uncover recent or remote illness including malignancy, an immune-compromised state, tuberculosis or other infection, trauma, previous hip dislocation, deep venous thrombosis, or hernia. A family history of cancer, systemic inflammatory arthritis, hip instability, or DJD is also useful. A social history detailing abuse of tobacco, alcohol, or illicit drugs is also important and may increase the index of suspicion for osteonecrosis of the femoral head or malignancy. Obtaining a sexual history as part of the social history can help evaluate the patient’s risk of a sexually transmitted infection, which can cause septic arthritis. Pain with menses also should be noted. The social history should include a review of the patient’s activities of daily living, work activities, hobbies, athletic activities, and impairments to these activities that are a result of the chief complaint. Participation in running, soccer, ballet, hockey, golf, tennis, martial arts, or rugby is specifically associated with hip pathology. A review of systems including recent fever, chills, malaise, night sweats, or unintended weight loss may raise red flags as well. The clinician should remember that genitourinary, gastrointestinal, neurologic, or vascular pathology can also masquerade as hip pain.
When eliciting the history, the clinician should ask the patient what he or she believes is causing the pain. The patient’s expectations of the encounter should be addressed, and he or she should be given a specific opportunity to ask questions or raise concerns. Additionally, the patient may provide or recall more pertinent history during the physical examination, and thus the clinician must listen attentively at all times ( Box 80-2 ).
Character and location of pain
Mechanism of injury (be specific if possible)
Duration of symptoms
Activity-related pain (e.g., does it subside with rest?)
Pain related to bowel or bladder activity or ingestion of food
Pain related to menses
Treatment history (injections, physical therapy, other physician evaluations)
Physical Examination
The physical examination of the hip consists of several steps, including inspection, symptom localization, measurements, ROM, and special maneuvers.
Inspection
Several important pieces of information can be obtained simply by observing the patient. Stance and gait inspection are essential components of the physical examination. The patient’s stance should be inspected for a slightly flexed position of the hip or knee, which may be indicative of hip pathology. The patient’s stance should also be inspected for gross atrophy, spinal malalignment, or pelvic obliquity. While sitting, the patient should be observed for slouching to the unaffected side to avoid excessive flexion. The gait should be observed in multiple planes and for six to eight strides in the frontal and sagittal plane.
The patient may present with one of several different gait abnormalities, including an antalgic gait, a pelvic wink, Trendelenburg’s gait, excessive pelvic internal or external rotation, or true or false leg length discrepancies. The antalgic gait involves a limp to decrease the time of stance phase on the affected side and limit weight bearing through the affected hip. An antalgic gait indicates pain in the hip, pelvis, or lower back. A pelvic wink is greater than 40 degrees of rotation in the axial plane toward the affected hip during terminal extension and signifies a hip flexion contracture in the setting of lumbar lordosis or forward-stooping posture. Trendelenburg’s gait, also known as an abductor lurch, involves a lurching of the trunk toward the side of the affected hip. Abductors normally stabilize the pelvis when the contralateral leg is raised. If the abductor muscles or the nerves supplying those muscles are injured or not functioning, the patient will lurch to the ipsilateral side to prevent pelvic sagging. A Trendelenburg sign can be elicited by having the patient raise the contralateral leg. A pelvic sag of more than 2 cm on the ipsilateral side is a positive Trendelenburg sign, indicating abductor pathology. Internal or external rotation should be noted both during gait and once again in the sitting position, which stabilizes the pelvis. Decreased internal rotation is a sign of internal hip pathology. Excessive internal rotation with decreased external rotation indicates increased femoral anteversion. A short leg limp during gait may indicate a true or false leg length discrepancy, or the limp may be secondary to iliotibial (IT) band pathology. Children with leg length discrepancy may present with a circumduction gait or a vaulting gait to clear the long leg.
Snapping or clicking noises should be noted as the patient walks. These noises can indicate iliopsoas, IT band, or intraarticular pathology. Lateral snapping is more likely with IT band pathology and generally is easily visualized. Audible snapping is more likely a result of iliopsoas tendon pathology.
Symptom Localization
Numerous techniques can help localize symptoms. A simple tool involves asking the patient to localize his or her pain by using a single finger. This technique can narrow the differential. Additionally, examination of this location can be reserved for the end of the examination, thus enhancing the patient’s trust by not causing pain at the beginning of the examination. This pain location in conjunction with Hilton’s law can help distinguish the cause of pain in the hip region. Hilton’s law states that “the same trunks of nerves whose branches supply the groups of muscles moving a joint furnish also a distribution of nerves to the skin over the insertion of the same muscles, and the interior of the joint receives its nerves from the same source.” This law helps explain why muscle spasms and superficial pain accompany hip pathology. The L3 nerve predominantly innervates the hip joint, and thus pain down the entire L3 dermatome (the anterior and medial thigh crossing laterally to the knee) can accompany hip pain. This pain can be confused with compression of the lateral femoral cutaneous nerve, also known as meralgia paresthetica, which will cause pain or neuralgia in the L2 or L3 dermatome.
Another useful observation is the C sign. The C sign occurs when a patient cups his or her hand above the greater trochanter when describing hip pain. The hand forms a “C” and is placed on the lateral hip, which may lead the clinician to mistakenly consider lateral hip pathology such as IT band or trochanteric bursitis ( Fig. 80-2 ). However, this sign is most characteristic of deep interior hip pain. When a C sign is observed, the clinician should ensure that the examination and subsequent testing include a complete evaluation for intraarticular hip pain.
