Hip pain: differential diagnosis.

Hip Pain: Differential Diagnosis Joseph H. Feinberg, MD Kessler Institute for Rehabilitation, West Orange, NJ This review discusses the many etiologies of hip pain and how to clinically evaluate. Both primary hip disorders and conditions that refer pain to the hip are included in the differential diagnosis. The key components to a history are reviewed with clinically relevant examples. A comprehensive physical exam is described that includes disease and injury-specific tests. Imaging studies and diagnostic tests available are outlined. Conditions of bursitis, snapping hip syndromes, myofascial pain, fibromyalgia, arthropathies, fractures, neurogenic pain, metabolic diseases, and neoplastic disorders will be discussed. Keywords: Hip; pain; physical examination; diagnosis; differential; medical history taking

Injuries and diseases of the hip can be very disabling. Pain often leads to an intolerance for weight bearing, impairing one's ability to participate in a broad range offunctional activities. Many structures can refer pain to the hip and groin region, and symptoms are often both confusing to the patient and challenging to the clinician. This review is intended to enable the clinician to more effectively manage patients who present with hip pain. Management includes a proper and pertinent history and a physical exam with disease- and injury-specific provocative tests. The appropriate diagnostic studies and their indications will be discussed. A differential diagnosis will be developed and in some cases management will be discussed. Hip pain either originates within the hip and groin or is "referred" from another source. Referred pain can originate from many different areas and systems of the body. Identifying the primary source of the pain is essential if one hopes to provide long-lasting relief of the symptoms. Acute presentations usually have a clear and identifiable cause, whereas in chronic conditions the true etiology may not be as obvious. Once functional goals are established, a treatment plan can then be developed.

THE HISTORY The importance of history taking cannot be overemphasized. A chief complaint should be clearly

established. It is easy for both the clinician and patient to get sidetracked from this and lose focus of the primary problem. One should then identify the onset of symptoms. A good clinical history will sometimes reveal that onset was earlier than the patient was aware of: A patient's chief complaint can sometimes differ from the chief concern, and both should be addressed. When there is related macro- or micro trauma, the mechanism of injury should also be determined. Once a history has been taken, a differential diagnosis is developed. This will direct the depth and focus of the physical exam. Patients who present with acute macrotrauma (e.g., falls, motor vehicle accidents) and have difficulty moving the hip or bearing weight require radiographs to rule out a fracture and/or hip dislocation. This clinical presentation requires further work-up even when radiographs are negative. Pelvic fractures are uncommon and are usually the result of a motor vehicle accident, an industrial accident, or a high fall. Both the athlete and nutritionally compromised individual are at risk for pelvic rami or femoral neck stress fractures. 1 Primary myofascial hip pain commonly results from acute trauma. A lateral blow to the hip and pelvis can lead to a contusion of the iliac crest (hip pointer). This common football injury will present with localized pain and swelling at the brim of the pelvis. 2 The injury can involve the abdominal

J Back Museuloshel Rehabi11994; 4(3):154-173 Copyright © 1994 Butterworth-Heinemann

Hip Pain: Differential Diagnosis

and/or gluteal muscles at their attachment sites. Athletes may be unable to bear weight on the involved site. When the abdominal muscles are involved patients complain of pain with deep inspiration or have difficulty with trunk rotation. Posterior contusions to the gluteal maximus and sciatic nerve can occur from a direct blow to the buttock. 2 Athletes will complain of pain in the buttocks and pain, numbness, and/or tingling radiatingdown the course of the sciatic nerve. Weakness from a sciatic neuropathy is uncommon, but when it is present it indicates a more serious injury. Quadriceps contusions result from anterior blows to the thigh. 3 The femoral nerve is fairly well protected and not usually injured. Acute compartment syndrome of the thigh is uncommon but has been reported in the quadriceps following a direct blow. 4 ,5 I"atients will present with increased pain with passive extension and knee extensor weakness, and may have sensory loss. Muscle contusions can also result in myositis ossificans (MO).6,7 MO is a condition that can develop after muscle has been traumatized. The injured muscle tissue will initially calcify. This eventually matures into heterotopic bone. Patients will develop localized pain, warmth, erythema, and swelling several weeks or months after the initial injury. Acute muscle strains in the hip and thigh region are usually seen in the athletic individual. They most often occur following a short sprint, jump, fall, or collision and are extremely painful. The athlete may notice a mass from muscle retraction (muscle tear), spasm, or a hematoma. A significant decrease or loss of motor function will always necessitate X-rays to rule out an avulsion fracture. A nerve injury (radiculopathy, plexopathy, peripheral neuropathy) should be considered as well, particularly if the patient complains of radiating pain, numbness, or tingling. Quadriceps strains, usually involving the rectus femoris, occur in sprinters and kickers. 8 Hyperextension injuries of the iliopsoas can cause a traction neuropathy to the femoral nerve. 9 The most frequently strained adductors are the longus and magnus. 8 They are often injured in sports that require kicking, for example, football, hockey, and baseball. Hamstring strains usually involve the short head of the biceps femoris. They are injured in runners or

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wide receivers (football), and in gymnasts when running for a vault. 8 Referred pain to the hip is common and should be considered in the absence of acute trauma or when symptoms do not clearly originate from the hip (Table 1). The concept of referred pain is often difficult for patients to understand. An explanation of referred pain enables the patient to better understand and to answer questions about symptoms they might otherwise have thought irrelevant. The major sources of referred pain are neurogenic (peripheral and central nervous system), vasculogenic (vascular system), viscerogenic (gastrointestinal and genitourinary system), and spondylogenic (spine), as well as other musculoskeletal structures (myofascial trigger points, bursitis, fractures, sacroiliac joint). The most common source of referred pain to the hip is the low back and includes both neurogenic (nerve root compression) and spondylogenic (facet or sacroiliac joint) causes. This underscores the importance of always questioning the

Table 1.

pain.

Neurogenic vs. non-neurogenic-referred

Neurogenic-Referred Pain L 1-S 1 radiculopathies Lumbosacral plexopathies Piriformis syndrome (Sciatic nerve compression) Diabetic amyotrophy Obturator nerve entrapment Posterior femoral cutaneous nerve Saphenous nerve Meralgia paresthetica (Lateral femoral cutaneous neuropathy) Referred Pain Facet syndrome Spondylolysis Spondylolisthesis Sacroiliac joint dysfunction Trigger points (Myofascial pain syndrome) Fractures Bursitis Hip arthritis

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patient about back-related symptoms during the history. Referred pain is often related to posture and positioning. Trigger points (TP) in patients with myofascial pain syndrome can cause both localized and referred symptoms that often closely resemble the referral patterns of a radiculopathy.l0.ll Patients may identify and describe the trigger point as a knot or lump. Referred pain can be "triggered" with palpation of the TP and is also often postural and position related. Fibromyalgia syndrome, often confused with myofascial pain syndrome, will present clinically with multiple muscle tender points. 12-16 Unlike the trigger points in myofascial pain syndrome, deep palpation produces muscle pain that is localized and does not radiate. Patients will identifY multiple sites as the cause of their pain. Pain with bursitis is frequently referred along the course of the muscle it underlies and nearby neurologic structures. 17 Obturator internus bursitis can refer pain to the back and buttock or along the course of the sciatic nerve. 18 Subtrochanteric bursitis commonly refers pain to the low back, lateral thigh, knee, and hip.17.19-22 Iliopectineal bursitis can refer pain along the course of the femoral nerve and anterior thigh. 23 Ischiogluteal bursitis can refer pain along the posterior femoral cutaneous or sciatic nerve. 24.25 Osteoarthritis (OA) commonly causes referred pain. Pain from OA of the hip will often radiate medially into the knee. 26 Some patients complain of knee pain only, making it difficult to convince them that their problem is coming from the hip. Arthritis of the sacroiliac joint, facet joint, and other bony structures of the spine (spinal stenosis) can all refer pain to the hip and groin regions. 10.27 Examples of viscerogenic referred pain include renal calculi (pain radiates into groin), ovarian cysts or an ectopic pregnancy (pain radiating into back or hip, or along course of sciatic nerve when there is direct compression), and diverticulitis or inguinal hernias (pain radiating across abdomen or back or into the groin). Referred pain to the buttocks can ·be a form of vasculogenic referred pain.28 It occurs in patients who have vascular claudication from stenosis of the distal aorta or common iliac vessels.

The relationship of physical activity, posture, and positioning to a patient's symptoms can be very revealing. Chronic overuse injuries and degenerative conditions are often secondary to biomechanical or anatomic alignment abnormalities. Identifying the onset and etiology may be difficult. Questions about work environment, athletic participation, and other daily and recreational activities help the clinician identifY risk factors for cumulative trauma that might not be apparent to the patient. Activities and positions that aggravate and alleviate symptoms (e.g., sitting, standing, walking, steps, lying) should be identified. Patients with ischiogluteal bursitis have pain that is usually worse with sitting on hard surfaces, cycling, and prolonged standing. 26 Because of the proximity of the sciatic and posterior femoral cutaneous nerves, patients may experience radicular-like symptoms or numbness in the posterior thigh. 24 They often have difficulty sleeping at night, unable to find a comfortable position. Subtrochanteric bursitis is often seen in runners. Their pain is on the "downside leg" because the drainage pitch of the road causes increased tension in the iliotibial band. 29 When severe, patients often walk with a limp.22 Symptoms are usually worse with squatting, lying on the involved side, climbing stairs, and walking.30 Patients with snapping hip syndrome usually only complain of the snapping sound. Pain is present when there is an associated bursitis. 30 The popping sound, which occurs during running and dancing activities, is caused by passage of the tensor fascia lata or gluteus maximus over the greater trochanter, or by the psoas catching the lesser trochanter or iliopectineal eminence.29.31-35 The radicular pain to the hip, thigh, buttock, or groin from a herniated disc is usually worse with prolonged sitting or standing. Symptoms are often reproduced with lumbar flexion or lateral extension, depending on the type of herniation. Unlike patients with ischiogluteal bursitis, symptoms are often relieved with the back supported or when lying on their side. A similar pattern of referred pain can be seen when the sciatic nerve is compressed by the piriformis muscle. 36- 41 The etiology of this is unclear, but patients often find relief with the knee flexed and the hip externally rotated. Compression of the lateral femoral cutaneous


nerve (meralgia paresthetica) from the ilioinguinal ligament, or from tight-fitting garments and heavy belts, will lead to a burning pain in the lateral thigh. 42- 44 Patients with spinal stenosis, spondylolisthesis, or facet syndrome will reproduce their low back and referred pain with activities that require back extension. 10.27 Pain secondary to spondylolysis is also worse with both low back and hip extension. lO Patients usually find comfort when sitting supported or with a small amount of low back flexion. Pain caused by malignancies is usually worse with rest, whereas vascular claudication of the buttocks can be precipitated with walking or sexual activity and is usually relieved with cessation of the activities. 28.45 The relationship of the time of day and environmental conditions to a patient's symptoms is valuable information in many conditions. The joint stiffness associated with OA conditions such as hip arthritis and facet syndrome is worse in the morning but short lasting (5-20 minutes), improves during the day, and then returns at the end of the day.26.46 The morning stiffness seen in patients with rheumatoid arthritis and the spondylarthropathies (ankylosing spondylitis, psoriatic arthritis) is usually longer lasting.4'-50 Patients with fibromyalgia syndrome have difficulty sleeping at night, causing them to be more aware of their symptoms at this time. 13-16.51 Pain associated with malignancies is usually worse at rest. 45 Osteoid osteoma is a benign bone tumor that causes pain that is worse at night. 45 Pain from infectious conditions tends to be constant and is not usually affected by the time of day. Weather conditions affect a number of hip disorders. Patients with arthritic conditions and fibromyalgia syndrome will note a worsening of symptoms with a sudden change in the weather. Osteoarthritic conditions are also worse in cold and humid conditions. The surface an athlete exercises on is an environmental factor that can precipitate a hip injury. Running on hard surfaces such as concrete sidewalks and, to a lesser extent, paved roads contributes to the development of stress fractures of the hip or pelvis. The course of the patient's symptoms is another important part of the patient's history. Most injuries

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secondary to macrotrauma (fractures, muscle tears, contusions) are usually self-evident when evaluated acutely and improve with time when there is early and appropriate management. Repetitive microtrauma and overuse conditions (bursitis, tendinitis, strains, stress fractures) will slowly progress and then may plateau until the faulty mechanics or causative factors are corrected. Progressive neurologic symptoms, particularly the loss of or change in motor, bowel, bladder, or sexual function, should be fully explored. They may indicate a myelopathy, conus medullaris syndrome, or cauda equina syndrome which can develop suddenly from a disc herniation, epidural abscess, or traumatic or pathologic spine fracture. Symptoms may appear in a more insidious manner from a spine tumor, degenerative spondylolisthesis, or spondylosis of the spine. If not addressed in an appropriate time frame, a patient can be left with permanent deficits. Osteoarthritis is the most common form of the many intraarticular hip disorders. It is a slowly progressive disease. 26.52 Patients with rheumatoid arthritis (RA) and the spondylarthropathies usually have a slow onset (weeks or months) followed by intermittent flare-ups. 47-50 A review of the patient's medical history should be thorough. It could identify an underlying condition that either was missed initially or was not considered by the patient to be contributory. This should include pertinent family history (rheumatologic diseases, osteoarthritis, cancer, diabetes, Paget's disease), a history of cancer or cancer risk factors, diabetes (peripheral neuropathy, infections), medications such as steroids (avascular necrosis), alcohol use (peripheral neuropathies), dietary habits (osteoporosis), and vascular disease (vascular claudication). Associated symptoms like fatigue and malaise (fibromyalgia syndrome, RA, and the spondylarthropathies), fevers (infections, spondylarthropathies, RA), and weight changes (malignancies, anorexia, bulemia) should be considered when appropriate.

PHYSICAL EXAM The hip can be one of the more challengingjoints to examine. Unlike the knee or ankle, the joint is

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not palpable, and one must rely on a number of provocative tests and maneuvers to identify intraarticular or bony abnormalities. Even many of the soft tissue structures are difficult to manually identify, but can usually be isolated with proper manual clinical skills. Injection or aspiration techniques are often helpful in making the diagnosis with bursitis, myofascial pain syndromes, and entrapment neuropathies, but require caution in the anterior hip and groin region because of the proximity of neurovascular structures and intraperitoneal organs. 53 A thorough understanding of muscle and joint mechanics is important when evaluating an individual with a pathologic gait. 54.55 Anatomic models of the muscle moment arms of the lower extremities have been developed. They have been used to estimate the relative muscle forces and how they affect the ligaments of the hip and intra-articular forces. 56- 6o Pain with weight bearing often indicates a problem at the joint or bony level. The hip bears forces approximately one-third body weight when standing, 2.4 to 2.6 times body weight when standing on one limb, and 1.3 to 5.8 times body weight during walking. 61 lbis can be reduced 40% with the use of a straight cane. 62

Visual Exam 'Ibe visual exam includes an inspection for skin changes, muscle atrophy, and anatomic abnormalities. A localized soft tissue mass or swelling may indicate a bursitis, an acute muscle contusion or tear with a hematoma, an avulsion fracture, myositis ossificans, a tumor, infection, or a deep vein thrombus. Asymmetric muscle atrophy is usually an indication of a radiculopathy or peripheral neuropathy but can also be seen with a tendon rupture. An ecchymosis may be seen with contusions, muscle tears, fractures, and patients with a bleeding diathesis. Vesciular skin lesions that have a dermatomal distribution may be found in cases of herpes zoster. Cafe-au-lait spots greater than 3 cm and greater than six in number are characteristic of neurofibromatosis. Skin rashes may be secondary to psoriatic arthritis, drug reactions, or one of the collagen vascular diseases. Obvious joint or bony deformity should raise suspicion of a fracture or dislocation. A step-off in the lumbosac-

ral spine can sometimes be observed and may indicate a spondylolisthesis.

Palpatory Exam The palpatory exam is done to identify both anatomic abnormalities and painful sites. A palpable mass following acute trauma that is not well defined usually indicates a muscle tear, a muscle spasm, or a hematoma. A mass that develops two to three weeks after the initial injury and is warm and erythematous may be the first indication of myositis ossificans. A bursitis usually presents with some localized swelling, warmth, and erythema, and no history of acute trauma. When the bursa sac is filled with fluid one can often appreciate a fluctuance. Soft tissue masses that are discreetly palpated usually indicate the presence of a cyst, tumor, or trigger point. Trigger points are usually identified as discreet nodules or bands within muscle tissue. There is no associated swelling and no warmth or erythema. The lumbar paraspinals, PSIS region, gluteus maxim us, and piriformis are common sites. II When palpated, one can often reproduce radiating pain and/or numbness that mimics a classic dermatome or nerve distribution. Patients with fibromyalgia syndrome will have multiple muscle tender points that will appear hypersensitive to even gentle palpation. These are not usually discreet masses and when deeply palpated produce localized' muscle pain without radiation. 12.15 During the manual exam of the spine, palpation of a step-off may indicate a spondylolisthesis. 1O Discomfort produced with pressure over or across the spinous process is relatively nonspecific for pain with a spondylogenic etiology.

Alignment Exam Malalignment can increase the risk of both acute traumatic and overuse injuries.17.63.64 The anatomic relationships of the joints of the lower extremities should be compared, looking for valgus and varus deformities, pes cavus or planus, spine mobility, hip anteversion, pelvic asymmetry, and leg length discrepancies. The normal lordotic curve of the lumbar spine should be accentuated with extension and reverse with forward flexion. Segmental motion should be


symmetrical with lateral side bending. The posterior-superior iliac spines (PSISs) and the anterior-superior iliac spines (ASISs) should be identified and line up evenly. They should rotate symmetrically while flexion and extension are done with the patient standing. This is repeated with the patient seated and the pelvis stabilized. Asymmetry may indicate sacroiliac dysfunction, scoliosis, or a leg length discrepancy. 63 Leg lengths can be compared while the patient lies supine. A true leg length discrepancy is determined by measuring the distance from the ASIS to the ipsilateral medial malleolus on each side. 61 An apparent leg length discrepancy is determined by measuring the distance fi'om the umbilicus to the medial malleolus on each side. 61 A relative leg length discrepancy is determined by aligning the pelvis neutrally to the torso and comparing the positions of the medial malleoli. A leg length discrepancy equal to or greater than one-half inch is considered significant and is a risk factor for subtrochanteric bursitis (involved side shorter) 17 and sacroiliac dysfunction. 61l

Gait Evaluation To evaluate ambulation, most of the lower extremity should be visualized. The patient should be observed, preferably wearing shorts and barefooted. Because patients may alter their "normal" gait when they are gowned and being observed, one should also observe the patient walking in their street clothes either befi)re or after the exam. Increased ankle pronation increases the degree of hip internal rotation; conversely, supination causes greater external rotation. This puts greater stress on the hip rotators (piriformis, obturator internus/externus, gemelli). Hyperpronation may predispose a patient to piriformis syndrome. Increased hip rotation can be traumatic to muscles that cross bony prominences (i.e., tensor fascia lata and greater trochanter) and may help precipitate a bursitis. A patient ambulates with an antalgic gait when there is pain in one lower extremity.61 The patient remains (bears weight) on the involved side for as short a time as possible. The Trendelenburg test is positive when a patient has weakness in the gluteus medius. 61 ,65 The uninvolved hip drops while the patient attempts to bear weight

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on the side with the weak gluteus medius. To compensate, the patient may walk with a gluteus medius lurch, lurching to the involved side while it is weight bearing. It is an attempt to shift the center of gravity over the involved side, and decrease the forces the hip abductors must produce.

Flexibility Exam Restrictions in motion limit functional capacity, decrease muscle strength (muscle length-tension relationship), and have an adverse effect on muscle and joint biomechanics. Hip range of motion can be limited because of intra-articular abnormalities, soft tissue restrictions, or simply pain. Normal hip flexion is 110°-120°, extension is 10°_ 30°, abduction is 30°_50°, adduction is 20°-30°, internal rotation is 30°_40°, and external rotation is 40°_60°.61,65 A relationship has been observed between decreased hip internal rotation and ankle inversion sprains. Limits in lower extremity flexibility are associated with an increase in the incidence of lower extremity football injuries. 66 Loss of internal rotation is one of the earliest findings on physical exam in the arthritic hip.26 Patients immobilized for a prolonged time period in a bed and chair may develop flexion contractures of the hip and lose extension. Patients with low back pain often have soft tissue restrictions in the hamstrings, psoas, rectus femoris, and piriformis, causing a loss of hip flexion, extension, and internal rotation. These restrictions are frequently asymmetric. Piriformis syndrome and obturator internus bursitis can lead to a loss of internal rotation. Ischiogluteal bursitis can cause restrictions in hip flexion, and subtrochanteric bursitis can lead to limitations in adduction. Hamstring strains are recurrent in patients with loss of hip flexion, and quadriceps strains are recurrent in patients with loss of extension. Ely test. The Ely test is used to test restrictions in hip extension by the rectus femoris. The hip is extended while the patient lies prone and the knee is fully flexed. Then extending the hip with knee extended can test the iliopsoas. 61,65 Thomas test. The Thomas test determines if there is a hip flexion contracture from the psoas, hip capsule, or joint. The patient lies supine and is asked to flex the contralateral hip and knee

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maximally while the examined hip is passively extended. The hip tested has a flexion contracture if it remains elevated from the exam table. 61,65 Popliteal angle. The popliteal angle is a reflection of hamstring flexibility. It is measured with the patient supine by initially flexing both the hip and knee to 90° and then slowly extending the knee until there is resistance. The straight leg raise, used to test for a radiculopathy, can also measure hamstring flexibility when elevation is not restricted secondary to pain. Ober test. The Ober test can be performed in two ways. The patient lies on their side with both legs lying straight parallel to the torso. The upper leg is abducted 30° to 45°, extended at the hip (originally described with hip in neutral), flexed at the knee and passively adducted. The leg should gently glide and adduct behind the lower leg. Resistance indicates a contracture or restriction in the tensor fascia lata (TFL) of the upper leg. A variation is to lay the patient prone, again with both legs straight. One leg is abducted with the hip extended and the knee flexed and then passively adducted to the midline. Any resistance in glide suggests abnormal tightness of the ipsilateral TFL.61,65 Craig test. The Craig test measures femoral anteversion. Anteversion of the hip is the angle the femoral neck makes with femoral condyles. It is the degree of forward projection of the femoral neck from the coronal plane of the shaft. Femoral anteversion is approximately 30° at birth. It decreases with maturation and lies between 8° and 15° in adults. It is measured with the patient lying prone and the knee flexed to 90°. The posterior aspect of the greater trochanter is palpated. The hip is then internally or externally rotated until the greater trochanter lies parallel to the exam table. The angle created by the lower leg and the vertical is the angle of anteversion or retroversion. Hip rotation (internal and external) can be tested in the same position. It can also be tested with the patient supine and both the hip and knee flexed to 90°.61 Sign of the buttock. A straight leg raise can be done to determine if loss of hip flexion is secondary to hamstring or gluteus maximus tightness. The patient lies supine with both legs resting on

the exam table. One leg is slowly elevated. If there is a limitation in hip flexion the knee is flexed. If the restrictions persist, they are most likely secondary to a tight gluteus maximus. 61

Provocative Tests Patrick test. The Patrick test, or FABER, is performed with the patient supine. One leg remains straight while the other hip is flexed, abducted, and externally rotated, the knee flexed, and the lateral malleolus of the ankle placed over the knee of the straight leg. FABER is derived from the triad of hip motion used to perform the test (Flexed, ABducted, Externally Rotated). Simultaneously, a posterior-directed force is applied to the knee that is flexed and the contralateral pelvis at the anterior-superior iliac spine. Pain will be elicited in either the sacroiliac joint or hip, depending on where the pathology is present. 61 ,65 Hip compression tests. Pathology in the hip joint can be identified by applying a compressive force. The patient lies supine with the knee in the resting position (10°-15° of hip and knee flexion) and a compressive force is applied through the longitudinal axis. The quadrant test is also performed with the patient supine. The hip and knee are maximally flexed and the hip is adducted so the knee faces the contralateral shoulder. While the patient applies some resistance the hip is abducted. Any pain, irregularity, or apprehension indicates a positive sign. 65 Straight leg raise. Straight leg raising is one of the oldest clinical tests performed and may indicate an L5 or Sl radiculopathy. With the patient supine, a straight leg is slowly elevated, while the contralateral leg rests on the exam table. 67 The ankle is kept neutrally positioned. The reproduction ofradicular symptoms usually before 70° constitutes a positive test and the angle of hip flexion is documented. If one then extends the hip to a point where the symptoms are alleviated, ankle dorsiflexion will often duplicate the positive straight leg raise. The radicular symptoms elicited with a positive straight leg raise should also be alleviated by relieving tension on the nerve root with simultaneous flexion of the knee. A straight leg raise performed with the patient sitting should


reproduce the same symptoms elicited with supine straight leg raising. If the straight leg raise produces radicular symptoms in the contralateral leg the test is considered to be a positive crossed straight leg raise. 68,69 Reverse straight leg raise. Reverse straight leg raising is performed by laying the patient prone and slowly elevating a straight leg. It can be used to detect a lumbar radiculopathy or femoral neuropathy. A positive test reproduces radicular symptoms down the leg being elevated (L2-L4 radiculopathy) or into the anterior thigh (femoral neuropathy).70 Piriformis stretch test. Piriformis compression of the sciatic nerve can be reproduced by maximally stretching the piriformis muscle. The patient lies supine and both legs lie flat on the exam table. One leg is raised and the hip and knee are maximally flexed. The hip is then internally rotated and fully adducted. Pain radiating down the leg constitutes a positive test for piriformis syndrome. Pelvic compression tests. The pelvic compression tests stress the sacroiliac (SI) joints. Pain reproduced in the SI joint region is evidence for SI dysfunction. With the patient lying supine a posterior-directed force is applied simultaneously at both anterior-superior iliac spines. The examiner then directs a force down and in at 45°. Then, with the patient lying on their side, downward force is applied at the lateral pelvic brim. 61

Neurologic Exam The recognition of neurologic disorders depends on a thorough understanding of the sensory and motor distribution of all the potential nerves, plexus, or roots involved as well as the potential sites of injury. Weakness may be a subjective finding; however, manual muscle testing remains one of the best and most sensitive clinical indicators of a neurologic injury. Isolation of the iliopsoas is done with patient sitting. By flexing the knee the rectus femoris is eliminated during hip flexion. The quadriceps minus the rectus femoris (vastus medialis, vastus lateralis, vastus intermedius) can be tested in the same seated position by extending the knee with the hip maintained in a flexed position. The rectus femoris is best isolated by

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straight leg raising with the patient supine. Extension of the hip with the patient prone and the knee extended tests both the hamstrings and gluteus maximus. Flexing the knee in the same position isolates the hamstrings. The gluteus maximus is best examined by extending the hip with knee flexed. The gluteus medius can be tested with simple abduction and the adductor brevis, longus, and magnus with simple adduction. Sensory abnormalities are often difficult to reproduce, but when consistent can be very informative. They can even be demonstrated when patients are unaware they exist. The absence, presence, and symmetry of reflexes is useful information as well; however, one cannot rule out neurologic injuries on the basis of intact reflexes. The reflexes of the quadriceps (L2, 3, 4), medial hamstring (L5, SI), and gastrocnemius (Sb S2) should all be tested. The causes of hip and groin pain will now be discussed in greater depth. Topics covered in other articles (heterotopic ossification, congenital and pediatric hip diseases, sports medicine injuries, and the hip in cerebral palsy) will not be reviewed.

BURSITIS Subtrochanteric bursitis can lead to pain radiating into the low back, lateral thigh and knee (pseudoradiculopathy), and hip.17-21,71 Those between the ages of 40 and 60 are more commonly affected. Two major bursae, the subgluteus medius bursa and subgluteus maximus bursa, and a minor bursa, the gluteus minimus bursa, are associated with the greater trochanter of the femur. 72 All three can be sources of inflammation. 20-22 Predisposing factors are low back pain, a herniated lumbar disc, leg length discrepancy, hip disease, rheumatologic conditions, hip trauma, and previous surgery and hemiparesis. These can lead to an alteration in normal hip mechanics and loss of hip internal rotation. 18,21,71,73 In many cases the bursitis can be strictly an overuse phenomenon. Patients will have a positive Ober and/or Patrick test. 21 Pain can be localized to the proximal

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lateral thigh and superficial to the greater trochanter. Patients will often walk with an antalgic gait. Palpation of the lower edge of the greater trochanter with the knee and hip moderately flexed may elicit a 'Jump sign."17 Pain is often present with hip motion; at the same time mobility may be unaffected. 73 Warmth and erythema are present, and when there is palpable swelling, fluid can often be aspirated. When purulent, the bursa must be incised and drained and followed with a course of appropriate antibiotics. Rarely, a tuberculous infection can involve this bursa. Local infiltration of xylocaine should provide instantaneous relief of symptoms, and, when not contraindicated, adding a long-acting steroid is effective. Leg length discrepancies should be corrected when identified. The iliopectineal bursa lies between the iliopsoas muscle anteriorly and the iliopectineal eminence posteriorly. Because of its proximity to the femoral nerve it can lead to referred pain along the anterior thigh when inflamed, in addition to localized symptoms. Tensing the iliopsoas or resistive hip flexion will reproduce the symptoms and pain. 23 Obturator internus bursitis has been described as a cause of buttock and low back pain. 18 Just beneath the piriformis, and functioning as a hip external rotator, symptoms can be reproduced by supine straight leg raising with the leg maximally adducted and internally rotated. When identified, this bursitis usually responds to conservative management of physical therapy and/or a steroid injection. Ischiogluteal bursitis can develop from prolonged sitting on hard surfaces, with chronic hamstring strains, or from prolonged standing. 25 Pain may be referred along the sciatic and/or posterior femoral cutaneous nerves. Patients will often have difficulty sleeping at night, unable to find a comfortable position. They will stand with a list toward the affected side and will have a shortened length of stride. Standing on their toes will be difficult, and they may ambulate with circumduction on the involved side. Both straight leg raising and Patrick's test will reproduce symptoms. Physical therapy for bursitis should include stretching exercises to increase flexibility of the muscles involved. It is also important to assess the

antagonist muscles and functional strengthening and address biomechanical abnormalities. Infiltration of a mixture of lidocaine and cortisone will provide pain relief and reduce inflammation but should always be followed by an appropriate program of physical therapy. 21 Ultrasound is routinely prescribed in treating bursitis; however, indications for its usage are controversial. In chronic conditions where scar tissue restricts motion, ultrasound as a deep-heating modality can enhance mobility and increase blood flow. Deep-heating modalities are contraindicated in acute inflammatory conditions, and the reported mechanical properties of ultrasound have not been well demonstrated in in vivo studies. 74.. 77 The diagnosis of bursitis is usually a clinical one, and, although radiographs might demonstrate calcifications, additional diagnostic studies are seldom needed. Those cases refractory t.o conservative management may require surgical intervention. 29

SNAPPING HIP SYNDROME The snapping hip syndrome has been described as an audible snap heard associated with pain as a thickened posterior border of the tensor fascia lata passed over the greater trochanter. 31-33 Passing of the anterior border of the gluteus maximus or of a band of fibrous tissue across the greater trochanter has also been reported. 34 Other extraarticular etiologies causing hip pain and associated with a snapping sound include the psoas tendon slipping over the iliopectineal eminence on the pubis,35 tenosynovitis of the iliopsoas tendon,78 passage of the iliofemoral ligaments over the anterior hip capsule,23,35,78 and the tendinous origin of the long head of the biceps femoris muscle crossing over the ischial tuberosity. 79 When snapping occurs in the region of the greater trochanter, the symptoms are usually reproduced by flexing the hip with the knee extended and the hip adducted. In a recent case report, symptoms were also reproduced with the knee flexed. 34 When snapping occurs in the region of the iliopectineal eminence, symptoms can be reproduced by extending the flexed, abducted, and externally rotated hip. X-rays are usually normal; however,


fluoroscopic bursography may demonstrate the subluxation of the tendon. 35 Computerized axial tomography (CT) scanning may demonstrate a bony prominence. 23 Those not responding to rest and nonsteroidal anti-inflammatory drugs or steroid injections usually require surgical intervention. A snapping sound associated with hip motion may also originate from an intra-articular source. Intra-articular causes include loose bodies, synovial chondromatosis, or hip subluxation. 35,78,80 CT scanning can demonstrate the presence of loose bodies or synovial chondromatosis.

MYOFASCIALjFIBROMYALGIA PAIN SYNDROME Localized pain within the muscles of the pelvic/hip region not related to an acute traumatic event (i.e., muscle contusion or strain) is commonly present in two clinical conditions, myofascial pain syndrome and fibromyalgia pain syndrome. Patients with myofascial-type pain will have focal, tender regions usually within muscle tissue that can be well defined from the surrounding soft tissue structures and when palpated appear nodular or fibrotic. When palpated these tender nodules, called trigger points, may cause radiation of pain, numbness, or tingling. These referral patterns have been well described. II Any persistent inflammatory process or biomechanical dysfunction may lead to the development of trigger points, which then can become a secondary source of pain. Trigger points within the pelvic, gluteal, and piriformis muscles may cause pain that is both localized and referred to the low back. 81 Pain in the buttock or pelvic region can result from trigger points in the paraspinals, quadrarus lumborum, and soleus muscles. 81 Chemical i~ections, dry needling, spray and stretch, acupressure, ultrasound therapy, and soft tissue mobilization have all been found to be effective. II ,82 When addressing pain that is secondary to a trigger point the primary etiology must be identified and treated as well to prevent recurrence. Fibromyalgia syndrome/fibrositis is a condition where patients complain of musculoskeletal pain,

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stiffness, and easy tatiguability.12,13 The only abnormal finding on clinical exam is the presence of numerous tender points which have been well described. 12 ,14,15 Two of these are present in the upper gluteal area and 2 cm posterior to the greater trochanter and can lead to pain in the hip and groin regions. Unlike trigger points, palpation of these tender points produces localized pain only and no radiation of symptoms. Although patients may complain of swelling, joint pain, weakness, numbness, or tingling, objective studies (electrodiagnostic studies, muscle biopsies, blood work) are usually normal. Difficulty sleeping is common and restoration of a normal sleep cycle with amitriptyline (10-25 mg) and cyclobenzaprine (10-20 mg) is often very effective. 16,51 Aerobic conditioning and attempts to minimize stress are also usually beneficial. 83

ARTHROPATHIES One of the most common forms of hip pain seen in a general practice is osteoarthritis of the hip. Age, family history, occupation, trauma, congenital hip dysplasia, slipped capital femoral epiphysis, and a number of neurogenic and metabolic disorders are predisposing factors. 52 ,84 Coxa vara, anteversion of the hip, and restrictions within the joint capsule, ligaments, or other soft tissue structures crossing the hip will alter normal alignment. This changes the distribution of forces within the joint and may eventually lead to joint degeneration. 26 OA of the hip is usually bilateral, but unilateral involvement is not uncommon, and 10% of these will eventually develop symptoms on the other side. 46 When the arthritic changes are very advanced in an asymmetrical pattern the clinician should look for a predisposing condition (e.g., avascular necrosis, slipped capital epiphysis) or a correctable biomechanical or anatomic abnormality. Patients will complain of pain in the hip, groin, and/or medial knee (along the distribution of the obturator nerve), have an antalgic gait, and initially lose internal rotation. Patients who become less active may develop a flexion contracture of the symptomatic hip. This can be demonstrated by a Thomas test. Stiffness when present lasts only

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a few minutes and improves with exercises. Cold and humid weather will intensify the discomfort. Radiographs alone are usually adequate and will show joint space narrowing, sclerosis, osteophytes, and subchondral cysts. 26,85 The hip joint is one of the joints less frequently involved in rheumatologic conditions (RA, Reiter's syndrome, ankylosing spondylitis (AS), psoriatic arthritis).47-50 Early morning stiffness is much worse than experienced with OA and discomfort is often experienced in the groin. 47 Radiographs of the hip will show uniform narrowing of the joint space, small subchondral erosions, and secondary sclerosis. 85 Osteophytes are absent in this condition, unlike in OA Erosions and periosteal changes at the ischial tuberosities and greater trochanter related to enthesopathy is a radiologic feature characteristic of Reiter's syndrome. Patients with Reiter's syndrome or AS can experience referred pain to the hip or the gluteal or groin region from either mechanical dysfunction or isolated involvement of the SI joint. Radiographs of the SI joints will demonstrate blurring of the subchondral margins accompanied by an adjacent reactive sclerosis. These findings are symmetrical in AS and usually asymmetrical in Reiter's syndrome. 86,87 When there is clinical evidence of hip involvement, ultrasonography is very sensitive in identifying an inflammatory process of the synovium when an effusion exists. 88 Because of the association of chronic steroid use in many of the rheumatologic disorders and collagen vascular diseases, avascular necrosis of the femoral head is a common complication and should be considered when hip or groin pain is present, particularly when radiographs appear normal. Rehabilitation of hip arthropathies should address anatomic changes (restrictions in motion), alignment abnormalities (leg length discrepancy), and biomechanical factors (gait, work, sports). Heating modalities are contraindicated during acute rheumatologic flare-ups but should be used in cases of osteoarthritis in conjunction with soft tissue mobilization techniques (manual oscillations, deep tissue massage, stretching) to help overcome capsular and other soft tissue restrictions. Strengthening programs must be individualized and are important for joint protection. The

muscles supporting an arthritic joint will often become deconditioned from disuse atrophy. Exercise programs that include motion while minimizing weight bearing and loading to the hip, such as stationary cycling and aquatic activities, should be encouraged. The use of a cane (held in contralateral hand) has been shown to reduce the hip weight-bearing forces by 40%.62

NEUROGENIC PAIN Neurogenic pain arises from either the central or peripheral nervous system. This review will be limited to the peripheral nervous system. The presence of objective neurologic abnormalities on physical exam are often an indication of a neurogenic source of referred symptoms. Motor deficits, however, can be secondary to muscle trauma (strains, complete tears, avulsion fractures) or just pain. Sensory deficits and abnormal reflexes are usually more direct indicators of neurologic injury. Radiculopathies are a common source of neurogenic and referred pain. Nerve root levels from Lr to S3 can all lead to pain in the hip and groin region when inflamed. 89 A patient may experience pain along a dermatomal (LJ-L3) and/or myotomal (L4-S3) pattern in the hip region. It is this author's opinion that at least 10% of radiculopathies will present with radicular symptoms only, with an absence of low back pain. Further complicating the picture may be the absence of significant abnormalities on magnetic resonance imaging (MRI), CT scans, and electromyography/ nerve conduction studies (EMG/NCS). Making a proper diagnosis and prescribing effective treatment often depends on one's clinical skills and judgment. Plain X-rays (with oblique views) are useful when pathology in the lumbar spine or SI joint is suspected. They provide information on alignment (spondylolisthesis), fractures (spondylolysis), rheumatologic disorders (sacroileitis), degenerative disc or bony disease (spondylosis), and other pathology (e.g., metabolic disorders, tumors, infections), all potentially a source of referred pain. JO ,27,8J Because the majority of lumbar radiculopathies (greater than 90%) respond to nonoperative treatments the diagnosis should


usually be made on clinical exam and does not routinely require an MRI, CT scan, or electrodiagnostic studies. 90-92 Straight leg raising is a sensitive but nonspecific test for an L5 and/or S 1 radiculopathy.67 The reproduction of radicular symptoms down the elevated leg is considered positive. Reproducing only low back pain with this maneuver is nonspecific for low back pain. Seated straight leg raising should also reproduce radicular symptoms. Simultaneous knee flexion should alleviate the referred pain if it is radicular in origin. Crossed straight leg raising is more specific for a radiculopathy but not as sensitive. 93 ,94 Reverse straight leg raising may reproduce radicular symptoms with involvement of nerve roots L2, L3, or L4, or may indicate a femoral neuropathy. 70 Imaging studies such as MRIs, CT scans, and bone scans are usually not needed in most cases where symptoms stem from the low back. These studies are appropriately ordered when management depends on them or when the clinical diagnosis is unclear. MRls will demonstrate nerve root compression from a herniated disc, cyst, tumor, or infection, whereas CT scans are more effective for identifYing bony anatomy (neuroforaminal or spinal stenosis). When a stress fracture is suspected from plain radiographs or on the basis of one's clinical exam, additional studies are indicated. Either a bone scan or an MRI is very sensitive and can be used to confirm this. An MRI study takes less time (45 minutes) and provides additional information on the soft tissue structures (e.g., disc, nerve root) being imaged, but costs between $700 and $900. Some patients are unable to tolerate lying in the narrow enclosed tunnel, and open MRI scanners now exist. A bone scan takes about half a day and costs about $300-$400. A single photon emission computed tomography (SPECT) scan increases the sensitivity of nuclear scanning but adds another $300-$400 to the cost. CT scans range between $400 and $500. These factors along with the overall clinical picture will dictate which study is most appropriate. Electromyography/nerve conduction studies (a routine EMG/NCS costs between $400 and $800) can help distinguish between nerve root injury

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and a more distal lesion in the lumbosacral plexus or peripheral nerve. 95 ,96 They are useful when there are significant neurologic deficits on physical exam, and when it is unclear if weakness is secondary to pain, disuse, or neurologic damage. They also help clarify the clinical picture when the patient has another underlying condition that could lead to similar findings, such as a diabetic peripheral neuropathy. EMG studies usually take at least one week before they demonstrate abnormal spontaneous activity (positive sharp waves and fibrillation potentials).97-99 This delay can sometimes be used to help determine whether there was a preexisting condition. Polyphasic potentials provide information on the timing and degree of recovery.98,100 Somatosensory evoked potentials may be positive acutely, and are noninvasive, but are less sensitive. 95,101,102 Nerve conduction studies are useful to rule out a peripheral nerve injury or disorder. Long latency evoked responses (H reflexes, F waves) may help localize a more proximal condition (nerve root, plexus). 103,104 Sciatic nerve entrapment can also give rise to referred pain in the hip, thigh, and leg. Piriformis compression of the sciatic nerve can cause pain localized to the piriformis, referred to the sacroiliac region, buttock, hip joint, or posterior thigh, or referred along the distribution of the sciatic nerve or its peroneal division. 36- 38 The piriformis will be tender to palpation, but this tenderness is common in many other conditions (e.g., radiculopathy, hip arthritis) and is not specific for piriformis syndrome. Patients may appear to have a shortened leg on the affected side from increased piriformis tension, or the leg might be externally rotated when the supine patient is at rest. 40,41 Straight leg raising may reproduce pain radiating down the sciatic nerve. The piriformis stretch test will also reproduce this radiating pain,39 but relieve radicular symptoms caused by a compressed nerve root. EMG/NCS can also be used to help distinguish between the two. 105 The common peroneal nerve has been shown to pass separately through the piriformis in approximately 10% of cadaveric legs, whereas the tibial component of the sciatic nerve takes its usual course beneath the musc1e. 106,107 The entire sciatic nerve was found

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to pass through the piriformis in 0.8% of the legs. examined. 106 The etiology of piriformis syndrome is not clear. Repetitive internal rotation of the thigh and leg during the pronation phase of running or other similar activities may lead to an overuse syndrome of the piriformis and other hip-external rotators. This can lead to constriction of these muscles over the sciatic nerve. The sciatic nerve may also be injured during total hip arthroplasties, secondary to dislocations, or compressed more distally by an inflamed bursa as it passes the ischial tuberosity. 108-11 I Lumbosacral plexopathies may present acutely with pain and/or weakness (pelvic trauma, diabetes), or have a more insidious onset (tumor, ovarian cyst). Diabetic amyotrophy is one of the most common causes ofa lumbosacral plexopathy.112,113 Symptoms can be gradual or sudden. There is wasting and weakness of the proximal legs and hip girdle, III and pain is usually present in the back, hips, and thighs. The femoral nerve is more frequently involved than other parts of the plexus. 114 Invasion by malignant tumors is another common cause of lumbosacral plexopathies. These tumors may arise from pelvis, abdominal, or retroperitoneal structures,115 and metastatic disease to the spine or retroperitoneal lymph nodes can secondarily invade either plexus. 115 A retroperitoneal hemorrhage or abscess of the psoas may lead to a lumbar plexopathy. Lumbar or sacral plexopathies can occur from pelvic trauma sustained in a motor vehicle accident or from a gunshot wound. CT scanning more accurately demonstrate fractures of the pelvis and are indicated when there has been significant macro trauma (motor vehicle accidents, major falls), whereas MR imaging is more sensitive for stress fractures associated with microtrauma. MRIs are also more accurate for detecting soft tissue tumors of muscle or nerve tissue and are indicated when the tumors are clinically suspected. 116 CT scans can better visualize tumors involving visceral structures. Electrodiagnostic studies are indicated for diagnostic purposes, when there is no clear etiology for the presenc~ of unilateral lower extremity neurologic deficits. They may also be used to identify the degree of neurologic injury, progression, or

recovery and can help prognosticate outcome after an acute plexus injury. Entrapments of peripheral nerves in the hip and pelvis region are uncommon and often difficult to diagnose even with EMG/NCS or somatosensory evoked potentials. 117 The femoral nerve may be injured with excessive hip extension stretching exercises or during hip surgery.IOS,lIS The saphenous nerve when entrapped in the adductor canal can cause medial knee pain. 1I9,120 Injuries to the obturator nerve are uncommon but are seen with pelvic fractures, compression from an obturator hernia or pelvic malignancy, or injuries during hip arthroplasties. 108,121,122 The lateral femoral cutaneous nerve may become entrapped by the ilioinguinal ligament, the psoas, by tight-fitting garments, or with heavy belts. Compression can also occur during pregnancy or with obesity. Patients with this condition, meralgia paresthetica, will complain of a burning-type pain along the lateral thigh. 42 -44 Iatrogenic injuries to the superior gluteal nerve may occur during hip surgery or from a misplaced injection. 123 The posterior femoral cutaneous nerve of the thigh can be compressed from an inflamed hamstring bursa or from prolonged bicycle riding. 24 Local infiltration of lidocaine at the site of entrapment can aid in the diagnosis if there is significant relief of symptoms. Electrodiagnostic studies also aid in making the diagnosis.

FRACTURES The hip joint is well protected with muscle and subcutaneous tissue from direct blows; nevertheless, fractures in the region of the hip account for 30% of all patients hospitalized in the United States for treatment of a fracture. The pain associated with these fractures makes weight bearing difficult for even the most stoic of patients. In the elderly, osteoporosis has been shown to be the underlying etiology of most of the hip fractures that result in significant morbidity and mortality. 124 When plain radiographs are negative and the clinical suspicion is high (patient unable to bear weight or has significant hip motion), a bone scan and an MRI are sensitive and accurate ways to


identify an occult or stress fracture of the hip or pelvis (pubic ramus, sacrum, acetabulum).125-129 A CT scan can more accurately map out fractures, particularly when there is comminution or displacement. Stress fractures can be insidious in their presentation, often undetectable on plain radiographs, especially within the first few weeks. They should always be considered for athletes who run long distances or on hard surfaces, and for nutritionally compromised individuals. Stress fractures of the pelvis pubic rami should be considered as well. 1 Avulsion fractures can usually be identified on plain radiographs but may be difficult to see in the sagittal plane when in the pelvis. They are associated with localized swelling and bleeding, and because of the large muscles involved will lead to significant alterations in gait biomechanics. Common sites are the greater trochanter, lesser trochanter, iliac crest, and ischial tuberosity. Management will depend on the degree of displacement and the associated mechanical alterations and functional deficits. Once edema and inflammation are managed, early motion and appropriate exercises may be started. The hip is a common area for pathologic fractures (e.g., tumors, metabolic bone disease). Tumors, Paget's disease, osteoporosis, hyperparathyroidism, osteomalacia, Gaucher's disease, osteogenesis imperfecta, Cushing's disease, and hyperthyroidism all predispose one to a fracture. 124,130-134 These fractures are often insidious in their development. Plain radiographs usually help to identify the underlying pathology as well as the fracture. MRIs, CT scans, and bone scans might be indicated as well, depending on the overall clinical setting. Fractures involving the articular surface and subcortical bone of the femoral head may develop secondary to avascular necrosis (AVN). The "crescent sign" on plain radiographs is pathognomonic for these fractures; however, bone scans and MRIs allow for earlier detection. This allows patients to modify their activities and helps prevent fractures. 93,135 AVN involving the entire femoral head may develop secondary to subcapital fractures (approx. 20% incidence) or posterior hip dislocations (8%).94 Extracapsular fractures rarely

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develop into AVN. Long-term steroid use, alcoholism, hyperlipidemia, pancreatitis, and hemoglobinopathies all increase the risk of AVN.26,85

METABOLIC CONDITIONS Pain in the hip or groin region may be the first symptom of a more diffuse or systemic process. Metabolic disease that includes osteoporosis, Paget's disease, hyperparathyroidism, hyperthyroidism, Gaucher's disease, osteogenesis imperfecta, Cushing's disease, and osteomalacia may present with bone pain and/or pathologic fractures. Paget's disease is a disorder characterized by increased bone resorption and secondary new bone formation that is architecturally abnormal. Patients may be asymptomatic or present with pain or skeletal deformities or develop changes in skin temperature. The sacrum is involved in 56%, the spine (usually lumbar) in 50%, the femur in 46%, and the pelvis in 21 % of patients with Paget's.136 Pathologic fractures occur with an incidence between 10% and 30%.136 The femoral neck and subtrochanteric regions are two of the most commonly involved sites. Plain radiographs are usually adequate except when one is concerned about malignant transformation. The incidence of malignant transformation ranges from as low as 0.9% to 12.5%.137,138 In a group of 65 patients with osteogenic sarcomas secondary to Paget's disease, 22 cases had tumors in the pelvis, six in the proximal femur, and two in the sacrum. 139 Patients develop severe disabling pain and often pulsatile swelling. Pathologic fractures are most common in the femoral neck. Serum alkaline phosphatase levels can be used as a guide for medical management of Paget's disease with calcitonin or diphosphonates, but are not of value when there is malignant transformation. Osteoporosis is usually a silent process leading to a thinning of bone and increasing the risk of hip fractures. 140 Th~re are many underlying diseases that can lead to osteoporosis (hyperparathyroidism, osteomalacia, osteogenesis imperfecta, sickle cell anemia, multiple myeloma, disuse), but most of the cases are idiopathic. 85,124 In the elderly, osteoporosis has been shown to be the

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BACK AND MUSCUWSKELETAL REHABILITATION / JULY 1994

underlying etiology of most hip fractures that result in significant morbidity and mortality. Rarely, patients will complain of bone pain, but most first present with a fracture. Women of northwestern European ethnic origin, post-menopausal, particularly when it is secondary to an oophorectomy, are at greatest risk. 140 Increased age and immobilization are additional risk factors. Osteoporosis can be identified on plain X-rays but not until there is usually 40% loss of bone mass. 141 A number of radiographic techniques can be used to estimate bone mass. 142 A transiliac bone biopsy is a reliable procedure for indicating osteoporosis and general skeletal disease. 143 Treatment consists of calcium supplementation, sodium fluoride, hormonal therapy (estrogens), vitamin D, and increased weight-bearing activities. 124,144-146 Transient osteoporesis ofthe hip is a condition, seen primarily in women in the third trimester of their pregnancy and in middle-aged men, that causes groin pain and limited hip motion. Treatment consists ofjoint protection, progressive ambulation, and analgesics. Spontaneous recovery usually happens within two to nine months. 147

NEOPLASTIC DISORDERS Malignant bone tumors of the hip or pelvis will usually present with localized pain either at rest or with activities that load the joint. They may also present as a pathologic fracture, particularly in weight-bearing structures such as the hip. Multiple myeloma is the most common neoplasm in adults (about 50% of all malignant bone tumors) and commonly involves the lumbar vertebral bodies and pelvis. 45 Osteogenic sarcoma is the most common in the pediatric and adolescent age groups, second overall for all ages (constitutes about 20% of all primary malignant tumors of bone), followed by chondrosarcoma, Ewing's sarcoma, and then malignant fibrous histiocytoma ofbone. 45,85 Metastatic disease to the femur can occur from prostate, breast, lung, kidney, and colon cancer and can also lead to localized pain or predispose one to a pathologic fracture. The femur is one of the most common sites of radiation-induced sar-

comas of the bone. 148 Malignant transformation in Paget's disease has already been discussed. CT scans and MRIs are valuable tools when looking for a malignancy. CT scanning better assesses calcifications, ossification, and periosteal reaction in neoplastic disorders. MR imaging represents the most accurate imaging for evaluating intramedullarily, for evaluating the extent of soft tissue involvement in tumors, and for identifYing involvement of neurovascular bundles. MRI can be used to monitor response to chemotherapy. 116 Benign bone lesions such as aneurysmal bone cyst, fibrous dysplasia, and nonossifYing fibromas are often asymptomatic until presenting as a pathologic fracture, or may be an incidental finding on X-rays. Aneurysmal bone cysts are most commonly seen in the second and third decade and may cause swelling, pain, or tenderness. Surgical curettage is usually effective but recurrence is common. 85 Osteoid osteomas and osteoblastomas are benign osteoblastic lesions that usually present with pain. Osteoid osteomas are small (less than 1 cm) and cause nocturnal pain, which is usually relieved with aspirin. Osteoblastomas may present with similar symptoms but are larger in size (greater than 1 cm). They may lead to more localized symptoms, such as swelling and tenderness, and when involving the spine can cause cord compression. 85 The lumbar spine, pelvis, and proximal femur are common sites of involvement. 45 When plain radiographs are negative these lesions are easily identified on a bone scan. Pigmented villonodular synovitis is a benign xanthomatous tumor of the synovium. When involving the hip, patients have an increasing dull, aching pain, limitation of motion, and may walk with a limp. 149 Radiographs will demonstrate irregular joint surface changes and cystic areas in the acetabulum and the femoral head and neck region. Treatment is usually a complete synovectomy.26

VASCULAR-RELATED PAIN Vascular-related hip pain is uncommon but buttock claudication may develop secondary to stenosis of the distal aorta or common iliac vessels. Pain is secondary to ischemia of local muscle tissue.


Involvement of the hypogastric artery has also been reported. 28 Patients often describe an aching pain associated with weakness, brought on by walking, sexual intercourse, or other forms of activity. There is relief with cessation of the activity. There may also be pain with sitting, secondary to vascular compression. When conservative management is unsuccessful, bypass surgery or transluminal angioplasty may be indicated.

CONCLUSION This review has discussed how a clinician can logistically approach a patient with hip pain by relying primarily on clinical expertise. Hip pain can be primary or it can be referred. The variability and complexity ofthe symptoms described should not be intimidating but should serve as a diagnostic challenge and help broaden the scope with which one practices. Despite its many possible

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causes, a skilled clinician should be able to diagnose hip pain on the basis of a history and physical exam. The history should always maintain focus on the chief complaint, yet include all detailed information that might be relevant. The physical exam should include visual inspection, observation, alignment and gait assessment, manual palpation, a neurologic evaluation, the appropriate tests for flexibility, and indicated provocative maneuvers. Imaging studies and electrodiagnostic tests should not be a knee-jerk reaction to diagnosis, but ordered when necessary and when they will have an impact on management.

ACKNOWLEDGMENT The author would like to thank Richard Brand, MD, and Steven Kirshblum, MD for their critical comments regarding this article.

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[Differential diagnosis of pediatric hip pain in MR tomography].

Synovial Chondromatosis: A Rare Differential Diagnosis of Hip Pain in a Child.

[Differential diagnosis of otorhinolaryngologic pain syndromes].

[Unusual differential diagnosis of posttraumatic back pain].

[Epiphyseal dysplasia of the hip joint, its diagnosis and differential diagnosis with MRT].

Headache and facial pain: differential diagnosis and treatment.

[Wilkie syndrome: A differential diagnosis of abdominal pain].

[Postinfectious myopathy. An important differential diagnosis in muscle pain].

Loin to groin pain: The importance of a differential diagnosis.

[Functional colonic pain. An important clinical and sonographic differential diagnosis].

Problems in the differential diagnosis of chronic pain.

Greater trochanteric hip pain.

Iliopsoas tendon rupture: a new differential for atraumatic groin pain post-total hip arthroplasty.

Ochronosis of the hip joint: differential diagnosis of inflammatory arthropathy with lytic lesion.

Intra-articular hip injections for lateral hip pain.

Differential Diagnosis: Child Abuse.

[Differential diagnosis of hoarseness].

[Diagnosis of periprosthetic hip infections].

[Differential diagnosis of hirsutism].

Differential diagnosis of hypercalcemia.

[Differential diagnosis of headaches].

Differential diagnosis of hyperthyroidism.

[Diagnosis and differential diagnosis of panceatic lesions].

[Angioedema: differential diagnosis].