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Clinical Orthopedic Examination Findings in the Lower Extremity: Correlation with Imaging Studies and Diagnostic Efficacy1 Aubrey J. Slaughter, MD Kirk A. Reynolds, MD, MS Kedar Jambhekar, MD Ryan M. David, DO S. Ashfaq Hasan, MD Tarun Pandey, MD, FRCR Abbreviations: ACL = anterior cruciate ligament, FAI = femoroacetabular impingement, LCL = lateral collateral ligament complex, MCL = medial collateral ligament, PCL = posterior cruciate ligament, PLC = posterolateral corner RadioGraphics 2014; 34:E41–E55 Published online 10.1148/rg.342125066 Content Codes: From the Department of Radiology, University of Arkansas for Medical Sciences, 4301 W Markham St, Little Rock, AR 72205 (A.J.S., K.J., R.M.D., T.P.); Department of Orthopaedic Surgery, University of Colorado, Boulder, Colo (K.A.R.); and Department of Orthopaedics, University of Maryland Medical Center, Baltimore, Md (S.A.H.). Presented as an education exhibit at the 2011 RSNA Annual Meeting. Received April 13, 2012; revision requested June 1; final revision received May 31, 2013; accepted June 5. All authors have no financial relationships to disclose. Address correspondence to A.J.S. (e-mail: [email protected]). 1

The lower-extremity anatomy is complex and normal function is dependent on intact osteochondral, musculotendinous, and ligamentous structures. Injury may result in pain and functional limitation. Specific clinical tests are used to help isolate and define the pathoanatomy; however, their terminology may be confusing to the radiologist and the diagnostic value of these tests may not be well understood. This article presents an algorithmic approach to evaluation of the hip, knee, and ankle to improve the radiologist’s understanding of lower-extremity physical examination. Knowledge of test terminology, clinical utility, and diagnostic accuracy will improve clinical and radiologic correlation. The article reviews the common clinical tests used to evaluate the lower extremity and provides an algorithm to establish a clinical examination road map and rapidly review the clinical utility and study hierarchy of a particular test. The sensitivity and specificity of the clinical tests and magnetic resonance (MR) imaging are reviewed because these parameters vary, and an understanding of the diagnostic utility of both the clinical and imaging tests is important in accurately formulating a definitive diagnosis. The structured algorithmic approach to lowerextremity examination described here, knowledge of test jargon, and familiarity with the diagnostic accuracy of the clinical and MR imaging examinations may help the radiologist focus image search patterns and provide detailed and clinically relevant reports. Online supplemental material is available for this article. ©

RSNA, 2014 • radiographics.rsna.org

Introduction

It is important for the musculoskeletal radiologist to recognize the clinical significance of the many orthopedic maneuvers used to evaluate internal derangements of the hip, knee, and ankle joints. Valuable information is gained from understanding the normal and abnormal test results, and this knowledge improves the radiologist’s ability to clinically correlate the radiologic findings, particularly those found at magnetic resonance (MR) imaging. This improves communication between the radiologist and orthopedist; helps avoid diagnostic errors; and, more important, focuses the report toward answering the clinical question. An understanding of the diagnostic accuracy and differential diagnoses of the orthopedic tests and the diagnostic utility of MR imaging provides insight into the usefulness of the tests. This article reviews the important periarticular structures of the hip, knee, and ankle. An algorithmic approach to clinical assessment of the major joints of the lower extremity begins with demonstration of the normal range of motion through the use of video clips. Next, the joint orientation tests are reviewed, wherever applicable. Finally, for

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Figure 1.  Assessment of hip pain. Evaluation of the hip begins with range-of-motion testing, followed by special tests that are used to evaluate the clinical entities and further pinpoint the abnormality.

each joint, the specialized tests that allow differentiation of various joint diseases are demonstrated and the differential diagnostic considerations are discussed. In addition, the diagnostic utility of the clinical and imaging examinations is reviewed.

Assessment of Hip Pain

When assessing the hip, it is important to remember that there is a large soft-tissue envelope surrounding the hip, and this may obscure disease, rendering findings at inspection of the joint misleading (1). A significant hip joint effusion may not be apparent due to this reason. Imaging therefore plays an important role in confirming the presence of a joint effusion or collections in or around the hip joint. Before a detailed evaluation of the hip joint is begun in a patient presenting with hip pain, a few important clinical observations should be noted, which include the site of pain, posture, and gait. Subjective evaluation of the site of pain helps in localization of the disease. Groin pain is commonly caused by hip joint disease, whereas buttock pain is more frequently related to spinal disease. However, it should be noted that not infrequently hip disorders result in pain being referred to the thigh and even to the knee (2). Other potential causes of “hip” pain include sacroiliac joint disease, meralgia paresthetica (a painful neuropathy of the lateral femoral cutaneous nerve of the thigh), inguinal hernia, or intrapelvic disease unrelated to orthopedics (2).

The posture of the spine and the legs can provide valuable information about the hip joints. For example, hyperlordosis of the spine could be secondary to a flexion contracture of the hip and resultant increased pelvic tilt (1). Contracture of the abductor or adductor muscle groups may lead to rotational scoliosis and accelerated intervertebral disk or facet joint degenerative disease, and the patient may present with back pain or sciatica (3). The converse is also true, and primary scoliosis may predispose to accelerated degenerative disease of the hips. Similarly, apparent leg lengthening or shortening can be due to an abduction or adduction contracture of the hip with secondary osteoarthritis (1). Evaluation of gait is a unique component of a hip examination. It may help localize the disease as extra-articular versus intra-articular (2). Antalgic gait results in a truncated gait and suggests that the cause of pain originates from an extra-articular cause (2). The patient shifts the weight of the upper body over the affected joint during the stance phase, which decreases the tension on the gluteal musculature and resultant stress on the joint. As a result, the stance phase of gait, as well as the duration of stress on the joint, is shortened (4). Trendelenburg gait (5) indicates an intra-articular cause of pain and results when the gluteal musculature is weak, which causes the pelvis to dip toward the affected side during the stance phase of gait. The upper body is shifted over the affected side to re-

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Table 1: Hip Pain Assessment Tests, Differential Diagnoses, and Diagnostic Value Clinical Entity and Special Tests Contractures   Hip extension test   Thomas test   Trendelenburg sign   Fingertip test   Test for rectus femoris  contracture   Piriformis test   Iliotibial tract test Degenerative hip disease   Anvil test

Differential Diagnoses Hip flexion contracture, spasticity Flexion contracture, hip deformities, osteoarthritis, inflammation Gluteus medius and minimus weakness Hamstring contracture, hip osteoarthritis, spinal disorder Rectus femoris contracture, hip disorder, lumbar spine disorder, psoas muscle inflammation, altered pelvic inclination Piriformis syndrome Iliotibial tract friction syndrome, bursitis, lateral meniscus tear

Diagnostic Value Not reported Not reported 72% sensitivity and 76% specificity for gluteus medius tendon tears (11) Not reported Not reported 88% sensitivity, 83% specificity (14) Not reported

Hip disease Groin/thigh pain: osteoarthritis, inflammation, femoral fracture, implant loosening Lumbar spine pain: intervertebral disk disease, rheumatoid spine disease Hip disorder, slipped capital femoral epiphysis, infection, osteoarthritis, tumor

Not reported

Impingement   Anterior FAI test

FAI, acetabular labral tear

  Posterior margin test

Posterior capsule or labral lesion

75% sensitivity, 43% specificity (22) Not reported

  Drehmann sign

Not reported

Note.—Numbers in parentheses are references. FAI = femoroacetabular impingement.

lieve the stress on the weak gluteal musculature, but the stance phase is not shortened as much as in antalgic gait. Therefore, Trendelenburg gait is more uniform than antalgic gait. When the gluteal muscles are weakened bilaterally, the patient appears to waddle (4,5). The preliminary evaluation of the hip is followed by assessment of hip range of motion, which will further direct the physical examination. Range-of-motion assessment is done by using the neutral-zero method (Movie 1) (6). This method uses a defined zero starting position for each joint, and all motions of a joint are measured according to this starting point. The normally accepted anatomic position of the joint, or another position, may be designated as the zero position. For the hip, the zero position is designated as the anatomic position, with the hip fully extended. Starting from this position, the degrees of motion are additive in the direction of movement. For example, abduction (movement away or lateral from midline) of the hip is quantified from 0° (neutral) up to 45°. Adduction of the hip (movement medially) is quantified from 0° to 30°.

A combination of subjective complaints and findings at inspection and range-of-motion testing will further direct the physical examination and direct the examining clinician toward specific orthopedic tests to determine specific diseases. Further evaluation is performed with function tests to evaluate the gluteal musculature, iliotibial band, and hip impingement. A summary of the evaluation of hip pain is shown in Figure 1. The clinical entities discussed, along with their differential diagnoses and sensitivity and specificity, are summarized in Table 1. On the basis of these findings, further evaluation with radiologic studies, frequently MR imaging, can be performed to aid in diagnosis and treatment of hip disease.

Hip Contractures Multiple tests exist to evaluate the hip musculature. Contractures result in shortening of the affected muscle and may be due to ischemia, neuropathy, muscle atrophy, or muscle infiltration. The hip extension test (7) evaluates for a flexion contracture of the hip, and the Thomas

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test (8) assesses hip extension and allows assessment of a fixed flexion contracture of the hip. The Trendelenburg sign (5), fingertip test (1), and test for rectus femoris contracture (1) evaluate for contractures involving the gluteal muscles, hamstrings, and rectus femoris, respectively. Specific tests, as described later, evaluate the piriformis muscle and the iliotibial band (Table 1). Flexion contractures of the hip are evaluated with the hip extension test (Movie 2a). With the patient prone, the pelvis is immobilized by one of the clinician’s hands, while the clinician’s other hand extends the leg of concern. The end point of hip extension occurs when there is pelvic motion or the lumbar spine goes into lordosis. Note is made of the angle between the examination table and the axis of the thigh to estimate the contracture. This is useful in evaluation of spasticity, in which there may be bilateral contractures (7). The hip is capable of 0°–15° of extension (9). The loss of extension and any flexion contracture is tested with the Thomas test (8) (Movie 2b). The patient is assessed in the supine position, and the hip and knee of the unaffected side are maximally flexed toward the chest. The affected extremity is extended. If a flexion contracture is present, particularly of the iliopsoas, the affected hip moves with the increasing flexion at the contralateral hip instead of remaining flat on the examination table. The angle formed by the flexed leg with the examination table allows estimation of the amount of fixed flexion contracture at the hip (9,10). Differential diagnostic considerations include osteoarthritis, articular deformities, and inflammation (1). The Trendelenburg sign (Movie 3a) is positive if, when standing on one leg (single-stance), the contralateral pelvis drops. This indicates weakness of the hip abductor muscles, specifically the gluteus medius and minimus, on the side of the stance leg (5). This sign has been shown to be 72% sensitive and 76% specific in diagnosis of gluteus medius tears (11). MR imaging has demonstrated 33%–100% sensitivity and 92%–100% specificity for diagnosis of gluteal tendon tears (12). During the fingertip test (Movie 3b), a positive result occurs when the patient notes a “pulling” pain in the posterior thigh and is able to bring the fingertips only into the general region of the foot. A difference is noted in comparison with the contralateral normal side and indicates a hamstring contracture. Decreased motion could also be due to hip osteoarthritis or a spinal disorder (1). A positive test for rectus femoris contracture (1) (Movie 3c) occurs when flexion of the thigh and extension of the knee is observed in one leg

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when the other leg is pulled close to the chest. The observed passive extension of the knee occurs secondary to the tightness of the rectus femoris. The rectus femoris crosses both the hip joint and knee joint and acts as a flexor and extensor of those joints, respectively. Positive results are also seen in flexion contractures of the hip secondary to a generalized hip disorder, but this is better assessed with the Thomas test discussed earlier. The test may also be positive in lumbar spine disorders, change in pelvic inclination, or psoas muscle inflammation (1). A tight piriformis causes pain in the piriformis muscle during the piriformis test (also known as the FAIR [flexion, adduction, internal rotation] test) (9) (Movie 3d). Pain in the buttock and sciatica may occur if the sciatic nerve is impinged by the piriformis (13). This test has demonstrated 88% sensitivity and 83% specificity in evaluation of piriformis syndrome (14). Piriformis syndrome is rare but may occur in people in whom the course of the sciatic nerve is altered from its normal location anterior to the muscle. The nerve may pass through the piriformis muscle or the nerve itself may be split, where a component of the nerve passes through the muscle, predisposing it to impingement (15). MR neurography has shown 64% sensitivity and 93% specificity in diagnosis of piriformis syndrome in patients with piriformis muscle asymmetry and hyperintensity of the sciatic nerve at the sciatic notch (16). The iliotibial tract test (Movie 3e) is positive when there is pain at 30°–60° of flexion or increased tone as the knee nears extension, which is reduced with flexion. Fluctuations may be palpated near the iliotibial band insertion (1). Pain will also be present at the insertion of the iliotibial band. This indicates iliotibial band friction syndrome, but it may also be seen with bursitis and lateral meniscus tears (1,15). An alternate test for iliotibial tract contracture is the Ober test (not shown) (3). In addition to showing flexion contracture of the tensor fascia lata, it can also demonstrate greater trochanteric bursitis if pain and tenderness are elicited in the region of the greater trochanteric bursa (1). Although the sensitivity and specificity of the iliotibial tract test and MR imaging have not been reported in evaluation of iliotibial band friction syndrome, to our knowledge, MR imaging is useful in demonstrating fluid and edema deep and superficial to the iliotibial band and corroborating the clinical suspicion. With respect to greater trochanteric bursitis, MR imaging is generally not routinely indicated because asymptomatic synovitis or signal abnormality is not infrequently seen at MR imaging (15).

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Internal Hip Joint Disease

Assessment is performed with the anterior femoroacetabular impingement test (20) and posterior margin test (1) (Table 1). The anterior femoroacetabular impingement test (Movie 5) is a moderately sensitive but nonspecific test that is positive if there is painful limited internal rotation and flexion with pain in the anterolateral and anteromedial hip (20). FAI is primarily a condition of young active patients and is proposed to result in premature osteoarthritis in nondysplastic hips (19). There are two types of FAI: cam and pincer. In cam FAI, there is an abnormal offset, or formation of an “osseous bump,” at the junction of the femoral head and neck, creating what is commonly known as a “pistol grip” deformity. In pincer FAI, there is overcoverage of the femoral head by the acetabulum, resulting in increased contact between the acetabulum and proximal femur. Frequently, a component of both cam and pincer types coexists in the same patient. Both cam and pincer FAI may result in labral damage and cartilage loss secondary to abnormal impaction of the femur against the acetabulum, and the damage may progress to frank osteoarthritis at an early age (19). It is worthwhile to note that labral damage occurs more commonly in the anterosuperior and superior aspects of the hip in cam-type FAI, as opposed to the posteroinferior position in pincer FAI (21). The importance of identifying FAI and the underlying abnormalities (abnormal femoral head-neck offset or acetabular overcoverage) lies in the ability to treat the underlying lesion and prevent progression to osteoarthritis. Currently, femoral neck osteoplasty for cam FAI and excision of the bony prominence at the acetabular rim for pincer FAI are performed (19). Labral repair may also be performed at the time of surgery if a labral tear is present. The sensitivity and specificity are shown in Table 1 (22). The posterior margin test (not shown) is performed with the patient supine. The clinician forcibly flexes, abducts, and externally rotates the hip. Next, the hip is extended in adduction and internal rotation. The test is positive if pain in the posterolateral region of the hip is elicited. This indicates a lesion of the posterior capsule or posterior labrum (1). MR imaging cannot demonstrate FAI because it is not a dynamic test; however, it shows high sensitivity and specificity in demonstration of changes associated with FAI. Studies that used nonenhanced MR imaging in patients with hip pain have demonstrated labral tears with a sensitivity of 96%–97% and specificity of 33%. MR imaging has shown femoral cartilage lesions with a sensitivity and specificity of 86%–93%

Many diseases may manifest as a painful hip. While a detailed evaluation of these entities is beyond the scope of this article, a useful approach is presented here. The first step should be to evaluate whether it is a native hip or the patient has undergone hip arthroplasty. A painful native hip may be due to osteoarthritis, infection, avascular necrosis, snapping hip, femoroacetabular impingement (FAI), labral tear, or slipped capital femoral epiphysis (in pediatric patients), whereas infection, pseudotumor, and component loosening are differential diagnostic considerations in a patient with hip arthroplasty (1,2,17). Clinical testing is not extremely useful in localizing intrinsic native hip joint disease, barring a few entities, because findings are frequently nonspecific. For example, initial clinical assessment of hip pain with the anvil test (1) and Drehmann sign (18) is nonspecific, with a broad differential diagnosis (Table 1). Since no robust clinical localizing tests allow differentiation between the various entities, imaging is frequently a mainstay in the diagnostic algorithm. In non-native hips, the reliance on imaging is even greater. Hence, in most cases, further evaluation may proceed with radiologic studies, hip fluid sampling, and laboratory analysis. If there is a question as to whether the hip is the source of pain, a diagnostic local anesthetic injection with or without steroid may be performed. The results of these ancillary tests direct further clinical assessment and management. A positive anvil test (Movie 4a) is present when there is pain in the hip and groin adjacent to the hip on tapping of the heel by the examiner. It indicates hip disease, and if the pain is in the groin or thigh, then the differential diagnostic considerations are osteoarthritis, inflammation, femoral fracture, or implant loosening (in a patient with hip arthroplasty). If the pain is in the lumbar spine, then intervertebral disk disease and rheumatoid spine disorders are the possible diseases (1). In total hip arthroplasty patients, pain in the hip suggests acetabular component loosening; pain along the anterior or lateral thigh suggests femoral stem loosening (1). A positive Drehmann sign (Movie 4b) indicates a disorder of the hip. The maneuver is positive when increasing external rotation of the hip is seen during hip flexion. Pain may or may not be present. Differential diagnostic considerations include slipped capital femoral epiphysis in adolescents, infection, tumor, or osteoarthritis (18).

Anterior FAI or Labral Tears Acetabular labral disease and anterior FAI are implicated in early osteoarthritis of the hip (19).

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Figure 2.  (a) Frontal radiograph of the right hip shows abnormal contour along the superior margin of the femur at the head-neck junction (arrow). (b) Axial oblique T2-weighted MR image (repetition time msec/echo time msec = 3000/60) of the hip shows features similar to those on the radiograph, with an abnormal contour at the femoral head-neck junction (arrow), findings associated with cam-type FAI. (c) Axial CT scan through the acetabulum shows evidence of acetabular retroversion. The anterior wall of the margin of the acetabulum (black arrow) is more laterally located compared with the posterior wall (white arrow) (normal angle of acetabular anteversion = 15°–20°).

and 72%–88%, respectively, and acetabular cartilage lesions with 91%–93% sensitivity and 75%–85% specificity (23). MR arthrography in patients with hip pain has been shown to demonstrate acetabular labral tears with 71% sensitivity and 44% specificity and articular cartilage lesions with 47% sensitivity and 89% specificity (24). In patients noted to have FAI, MR arthrography demonstrates sensitivities of 20%–100% and specificities of 40%–94% in evaluation of the acetabular cartilage, depending on location (25). Morphologic changes in FAI are also well evaluated with radiography and computed tomography (CT). A pelvic radiograph may demonstrate the pistol-grip deformity and focal anterior acetabular wall overcoverage (the crossover sign), and a frog lateral view can be used to demonstrate an abnormal a angle. Acetabular retroversion has also been implicated in FAI and can be evaluated on a CT scan (Fig 2) (19,26).

While FAI is a clinical diagnosis, provocative clinical testing in itself is not entirely sensitive or specific. Hence, in the setting of hip pain, imaging is frequently performed to show acetabular labral damage, cartilage changes associated with impingement, and morphologic changes to diagnose FAI. Ischiofemoral impingement is another less common but now well-known form of impingement that can result in hip pain. While no special test has been described, to our knowledge, the presence of ischiofemoral impingement may be indicated by pain caused by a combination of hip extension, adduction, and external rotation. MR imaging demonstrates inflammation and edema in the ischiofemoral space and quadratus femoris, an appearance distinct from an acute tear (Fig 3) (27). The MR imaging findings, when present, can support the clinical suspicion of ischiofemoral impingement. This entity is a known complication after total hip replacement

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Meniscus Injury

Figure 3.  Axial fat-suppressed proton-density– weighted MR image (2500/20) shows subtle edema within the quadratus femoris muscle (arrow), a finding seen with ischiofemoral impingement. (Courtesy of Phillip Tirman, MD.)

and recently has also been recognized in the orthopedic literature as a problem in the unreplaced joint (28). The sensitivities and specificities of the clinical tests are listed in Table 1 (11,14,22).

Assessment of Knee Pain

Evaluation of the patient with knee pain also begins with the history of the injury. Twisting injuries with delayed effusion are more consistent with meniscal disease, whereas immediate effusion after a valgus load and twisting injury is more consistent with an anterior cruciate ligament (ACL) injury. Individuals with an ACL injury will often report hearing or feeling a “pop” at the time of injury. Palpation for the point of maximal tenderness followed by assessment of range of motion is the first portion of the orthopedic physical examination (29). These findings will further guide the examination toward special tests, with specific focus on the presumed area of disease (eg, meniscus, cruciate ligaments, collateral ligaments). Orthopedic special tests provide significant clinical information that guides treatment and further evaluation with advanced imaging. Knee pain assessment begins with range-ofmotion testing with the neutral-zero method (6) (Movie 6). The neutral position is designated as the anatomic position, with the knee extended. Further evaluation proceeds with function tests evaluating for meniscal injury, ligament instability, and patellar abnormalities (Table 2). The algorithm for the assessment of knee pain is shown in Figure 4. Table 2 summarizes the clinical entities, differential diagnoses, and significance of the tests discussed.

The McMurray test (30) (Movie 7) is the most commonly used test to evaluate for meniscal disease (Table 2). Pain with a palpable or audible pop in abduction and external rotation indicates a medial meniscal lesion. Pain with a palpable or audible pop in internal rotation indicates a lateral meniscal lesion (30). False-positive cases include cartilage lesions, synovial abnormalities, and ligamentous lesions. Sensitivity and specificity are shown in Table 2 (31). With regard to the medial meniscus, MR imaging demonstrates 47%–76% sensitivity, 52%–95% specificity, and 63%–73% accuracy, depending on the study (31,32). Values for evaluation of the lateral meniscus are 61%–100%, 75%–92%, and 78%–85% for sensitivity, specificity, and accuracy, respectively (31,32).

Ligamentous Instability Assessment of the ligaments begins with the ACL, and common tests include the pivot shift test (33), Lachman test (34), and anterior drawer test (10) (Table 2). Valgus stress causes anterior subluxation of the tibia with the knee in extension and a positive pivot shift test (Movie 8a) in cases of ACL tear (33). Causes of a false-negative pivot shift test include a high-grade medial collateral ligament (MCL) tear, a bucket-handle tear of the medial or lateral meniscus, or extensive osteophytes in the lateral compartment (29). The Lachman test (Movie 8b) demonstrates mobility of the tibia with respect to the femur without a hard stop in cases of an ACL tear (34). If there is a hard anterior end point within 3 mm, then the ACL is intact; however, if the end point exceeds 5 mm, then the ACL is lax or there is evidence of remote trauma. An ACL tear is diagnosed if there is a soft end point or no end point. A false-negative examination may occur in improper stabilization of the femur, meniscal lesion, intracondylar osteophytes, or medially rotated tibia (29,34). The anterior drawer test (Movie 8c) is also used in assessment of the ACL and is positive when there is anterior displacement of the tibia with a soft end point, indicative of chronic ACL insufficiency (10). The anterior drawer test may be negative in acute injuries due to coexisting injuries and pain. A false-negative result may also occur if the knee is rotated while the test is being performed, secondary to twisting of the peripheral ligaments and capsular structures. It is important to note that to interpret an apparent anterior drawer test as truly positive, the posterior drawer test (discussed later) must be negative (29).

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Table 2: Knee Pain Assessment Tests, Differential Diagnoses, and Diagnostic Value Clinical Entity and Special Tests Meniscus injury   McMurray test

Ligament instability   Pivot shift test   Lachman test   Anterior drawer test   Posterior drawer test   Dial test   Varus stress test   Valgus stress test

Patellar abnormalities   Subluxation suppression test   Patella grind test

Differential Diagnoses

Diagnostic Value

Meniscal tear, articular cartilage injury, synovial disorders, ligamentous injury

Medial: 86% sensitivity, 73% specificity, 79% accuracy Lateral: 56% sensitivity, 95% specificity, 85% accuracy (31)

ACL tear, patellar dislocation, osteochondral injury, peripheral meniscal tear ACL tear, patellar dislocation, osteochondral injury, peripheral meniscal tear ACL tear, patellar dislocation, osteochondral injury, peripheral meniscal tear PCL tear, knee ligamentous in­ jury, knee dislocation, posterolateral corner injury PCL tear, concurrent PCL injury LCL injury; ACL, PCL, PLC ligamentous injuries; knee dislocation MCL injury, distal femoral physeal fracture, ACL tear, meniscal tears, chondral injuries, patellar subluxation, pes tendinitis

98% sensitivity, 24% specificity (35)

Lateral or medial patella subluxation Patellofemoral pain syndrome

Not reported

76%–98% sensitivity, 89%–96% specificity (36) 92% sensitivity, 91% specificity (35) 90% sensitivity, 99% specificity (39) Not reported Not reported Not reported

Not reported

Note.—Numbers in parentheses are references. ACL = anterior cruciate ligament, LCL = lateral collateral ligament complex, MCL = medial collateral ligament, PCL = posterior cruciate ligament, PLC = posterolateral corner.

The differential diagnostic considerations for these three tests include patellar dislocation, osteochondral injury, and peripheral meniscus tears (10). Table 2 lists the sensitivities and specificities of these three tests (35,36). MR imaging is highly sensitive and specific in evaluation of ACL injury, with reported sensitivity of 77%–96%, specificity of 93%–100%, and accuracy of 93%–98%, but does not affect management in cases with obvious physical findings of ACL tear (10,31,32,36,37). The posterior cruciate ligament (PCL) is assessed with the posterior drawer sign (38) and dial test (38) (Table 2). Posterior translation of the knee is assessed in neutral, internal, and external rotation, similar to the anterior drawer test, and posterior translation of the tibial plateau on the femur indicates a positive posterior drawer test (38) (Movie 8d). Knee ligamentous injury, dislocation, and posterolat-

eral corner (PLC) injury make up the differential diagnosis (10,38). Table 2 lists the sensitivity and specificity (39). During the dial test (38) (Movie 8e), initial testing is performed at 30° of knee flexion, and any external rotation of the tibia is noted. Next, external rotation at 90° of flexion is tested. It is useful to track the position of the tibial tubercle to determine the degree of external rotation. The test is performed on both knees, and the results are compared. Increased external rotation compared with that of the contralateral, uninjured knee at 30° of flexion indicates an injury to the PLC. Persistent or further increase of external rotation at 90° of knee flexion indicates a concomitant tear of the PCL. An isolated PLC injury will not result in increased external rotation at 90° of flexion because in that amount of flexion, an intact PCL acts as a restraint against varus and external rotation force (40,41).

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Figure 4.  Assessment of knee pain. Evaluation of the knee begins with range-of-motion testing, followed by special tests that are used to evaluate the clinical entities and further pinpoint the disease.

For a truly positive dial test, the external rotation of the affected knee has to be increased when compared with that of the contralateral knee. A side-to-side increase of external rotation of 10°–15°, with the knee flexed to 30°, suggests a severe PLC injury. MR imaging is highly sensitive and specific in evaluation of PCL injury, with reported sensitivity of 94%, specificity of 92%–99%, and accuracy of 99% (10,37,42). The varus and valgus stress tests (43) allow assessment of the lateral collateral ligament complex (LCL) and MCL, respectively. The varus stress test is performed both with the knee in full extension and at 30° of flexion. Increased opening of the lateral joint with or without pain on application of varus stress indicates a positive test. The differential diagnosis includes injury to the ACL, PCL, or PLC or knee dislocation (10,43). MR imaging is 93% and 100% accurate in detection of biceps femoris and LCL injury, respectively (44). Application of valgus stress with resultant opening of the medial joint line with or without pain is suggestive of injury to the MCL (43). As with the varus stress test, the valgus stress test (Movie 9) is performed with the knee in full extension and with the knee in 30° of flexion. The degree of opening allows differentiation between grade I–III injuries. Distal femoral physeal fracture, ACL tear, meniscal tear, chondral injuries, patellar subluxation or dislocation, and pes tendinosis are included in the differential diagnosis.

MR imaging is useful in demonstrating the extent of MCL injury that is suspected clinically and is 86% sensitive and accurate (Fig 5) (45).

Patellar Abnormalities Evaluation of the patella is performed with the subluxation suppression test (29) and patella grind test (46) (Table 2). Subluxation of the patella is assessed with the subluxation suppression test (Movie 10a). A positive test is indicated by abnormal lateral (or medial) patellar subluxation (or reduction by the clinician’s fingers) during active flexion of the knee (29). The patella grind test (Movie 10b) indicates patellofemoral pain syndrome when positive, which is indicated by pain during the superior movement of the patella during quadriceps contraction (46). MR imaging is useful in evaluation of patellar tracking abnormalities and may demonstrate impingement of the quadriceps or Hoffa fat pads (Fig 6), thickening of the lateral patellar retinaculum, or marrow edema. Sensitivities ranging from 0% (grade I) to 83%–89% (grade IV) and specificities of 96%–100% (depending on grade) are reported for MR imaging evaluation of lateral patellar dislocations (47). In evaluation of recurrent lateral patellar dislocations, MR imaging demonstrates sensitivities of 14%–70% and specificities of 91%–98%, depending on grade (47). In evaluation of chondromalacia patellae, MR imaging shows increased cartilage signal, cartilage loss, and underlying marrow changes with 60% sensitivity, 84% specificity, and 73% accuracy (48).

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Figure 5.  Coronal fat-suppressed T2weighted MR images (3000/60) show the normal appearance of the MCL (arrow in a); fluid or edema superficial to an intact MCL (arrow in b), a finding consistent with a grade I MCL sprain; and a complete tear (grade III) of the proximal femoral attachment of the MCL (arrow in c).

Table 2 lists the sensitivities and specificities of the clinical tests (31,35,36,39).

Assessment of Ankle Pain

Evaluation of a patient with an ankle injury can be slightly more complex than evaluation of a patient with hip or knee joint injury. This is partly related to the proximity of the smaller articulations of the foot and patterns of referred pain. Initial assessment, like with other joints, is directed by the patient history. Assessment of range of motion, followed by specific orthopedic special tests, not only helps formulate treatment options but also guides further evaluation with advanced imaging techniques. Evaluation of the ankle begins with testing of ankle range of motion, and as with the other joints, is assessed with the neutral-zero method

(6) (Movie 11). The neutral position is the anatomic position of the ankle. Further evaluation with function tests is subsequently performed. The workup of ankle pain is shown in Figure 7. Table 3 summarizes the clinical entities, differential diagnoses, and significance of the maneuvers.

Instability: Syndesmosis The ankle syndesmosis is evaluated with the external rotation stress test (Kleiger test) (49) and squeeze test (50) (Table 3). The external rotation stress test (Movie 12a) is positive if there is pain at the anterolateral aspect of the distal tibiofibular syndesmosis and indicates syndesmotic injury. Pain at the medial aspect of the ankle in plantar flexion indicates a deltoid ligament injury (49).

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Figure 6.  (a, b) Sagittal (a) and coronal (b) T2-weighted MR images (3700/90) through the knee show abnormal high signal intensity along the superolateral Hoffa fat pad (arrow), suggestive of fat pad impingement and commonly seen with patellar tracking abnormalities. (c) Sagittal fat-suppressed T2-weighted MR image (3500/70) shows increased signal intensity within the quadriceps fat pad (arrows), consistent with quadriceps fat pad impingement.

Pain at the distal tibiofibular syndesmosis during the squeeze test (Movie 12b) indicates disruption of the distal syndesmosis (50). The differential diagnostic considerations for both tests include peroneal tendon tears, subluxations, or dislocations; fractures of the anterior process of the calcaneus, lateral process of the talus, or base of the fifth metatarsal; or an os trigonum (10).

Instability: Ligaments Instability of the collateral ligaments is tested with the talar tilt test 1 (43,51) and talar tilt test 2 (51,52) and the anterior drawer test (10) (Table 3). The talar tilt test 1 (varus stress test) (Movie 13a) is positive if there is lateral gapping or pain with application of an inversion force to the

talocrural and subtalar joint (43,51). It indicates calcaneofibular ligament and anterior talofibular ligament injuries (51,52). The affected side should always be compared with the contralateral normal side to exclude physiologic laxity, and dorsiflexion of the ankle locks the subtalar joint and increases sensitivity. The talar tilt test 2 (valgus stress test) (Movie 13b) is positive if there is pain or excessive tilting of the talus on the medial side of the ankle mortise with application of an eversion force to the calcaneus. A positive test indicates injury to the deltoid ligament, particularly the tibiocalcaneal ligament (51,52). Increased forward motion of the talus compared with the contralateral side during the anterior

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Table 3: Ankle Pain Assessment Tests, Differential Diagnoses, and Diagnostic Value Clinical Entity and Special Tests Instability   External rotation stress test

Differential Diagnoses

Diagnostic Value Not reported

  Anterior drawer test

Pain at anterolateral distal tibiofibular syndesmosis: syndesmotic injury Medial pain in plantar flexion: deltoid ligament injury; peroneal tendon tears, subluxation, or dislocation; fractures; os trigonum Distal syndesmosis disruption; peroneal tendon tears, subluxation, or dislocation; fractures; os trigonum Calcaneofibular ligament and anterior talofibular ligament injuries Deltoid ligament injury, particularly tibiocalcaneal ligament Anterior talofibular ligament injury

Hindfoot   Thompson test

Achilles tendon tear, tendinosis

  Hoffa sign

Chronic Achilles tendon tear

96% sensitivity (57) Low-grade partial tears may cause false-negative result (52) Not reported

  Squeeze test   Talar tilt test 1   Talar tilt test 2

Not reported Not reported Not reported 96% sensitivity, 84% specificity (53)

Note.—Numbers in parentheses are references.

Figure 7.  Assessment of ankle pain. Evaluation of the ankle begins with range-of-motion testing, followed by special tests that are used to evaluate the clinical entities and further pinpoint syndesmotic, ligamentous, and hindfoot disease.

drawer test (Movie 13c) constitutes a positive test and suggests injury to the anterior talofibular ligament (10). The sensitivity and specificity are listed in Table 3 (53). Comparing results of the talar tilt test 1 with results of the anterior drawer test helps identify isolated abnormalities of the anterior talofibular ligament.

MR imaging evaluation of the unstable ankle is useful in identifying the location and extent of ligamentous injury and can support the clinical examination findings. It has demonstrated 100% sensitivity, 70%–93% specificity, and 84%–97% accuracy in evaluation of injury to the anteroinferior tibiofibular ligament and 100% sensitivity, 94%–100% specificity, and 95%–100% accuracy

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Figure 8.  Sagittal T1-weighted (500/15) (a) and T2-weighted (3400/100) (b) fat-suppressed MR images show an avulsion of the Achilles tendon from its insertion on the calcaneal tuberosity. A bone fragment is seen avulsed with the tendon (arrows).

in evaluation of the posteroinferior tibiofibular ligament (54).

Hindfoot Injury to the Achilles tendon, located within the hindfoot, is indicated by a positive Thompson test (55) and Hoffa sign (52) (Table 3). Decreased or absent plantar flexion of the foot constitutes a positive Thompson test (Movie 14a) (55) and indicates a tear of the Achilles tendon. The differential diagnostic consideration is tendinosis. A positive Hoffa sign (Movie 14b) is seen with decreased tone in the Achilles tendon and increased dorsiflexion and indicates a chronic Achilles tendon tear (52). MR imaging is 94% sensitive, 81% specific, and 89% accurate in detecting injury to the Achilles tendon (56). It is useful in evaluation of the Achilles tendon because low-grade partial tears may cause a false-negative Thompson test (52), and the sensitivity and specificity of the Hoffa sign have not been reported, to our knowledge (Fig 8). Table 3 summarizes the sensitivities and specificities of the clinical tests (53,57).

Conclusion

It is advantageous for radiologists to understand the meaning and clinical implications of the many orthopedic tests used in evaluation of internal derangements of the hip, knee, and ankle. Such

knowledge can be used to generate focused radiologic reports and serves to enhance communication between the radiologist and the orthopedic surgeon. Overall, this results in better patient care and clinical outcomes. Acknowledgment.—We thank Phillip Tirman, MD, for

the MR image of ischiofemoral impingement.

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Teaching Points

March-April Issue 2014

Clinical Orthopedic Examination Findings in the Lower Extremity: Correlation with Imaging Studies and Diagnostic Efficacy Aubrey J. Slaughter, MD • Kirk A. Reynolds, MD, MS • Kedar Jambhekar, MD • Ryan M. David, DO • S. Ashfaq Hasan, MD • Tarun Pandey, MD, FRCR RadioGraphics 2014; 34:E41–E55 • Published online 10.1148/rg.342125066 • Content Codes:

Page E45 In total hip arthroplasty patients, pain in the hip suggests acetabular component loosening; pain along the anterior or lateral thigh suggests femoral stem loosening. Page E46 While FAI is a clinical diagnosis, provocative clinical testing in itself is not entirely sensitive or specific. Hence, in the setting of hip pain, imaging is frequently performed to show acetabular labral damage, cartilage changes associated with impingement, and morphologic changes to diagnose FAI. Page E47 The anterior drawer test may be negative in acute injuries due to coexisting injuries and pain. A falsenegative result may also occur if the knee is rotated while the test is being performed, secondary to twisting of the peripheral ligaments and capsular structures. It is important to note that to interpret an apparent anterior drawer test as truly positive, the posterior drawer test (discussed later) must be negative. Page E48–E49 For a truly positive dial test, the external rotation of the affected knee has to be increased when compared with that of the contralateral knee. A side-to-side increase of external rotation of 10°–15°, with the knee flexed to 30°, suggests a severe PLC injury. Page E52 Comparing results of the talar tilt test 1 with results of the anterior drawer test helps identify isolated abnormalities of the anterior talofibular ligament.