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Clinical and Radiographic Analysis of Perthes Deformity in the Adolescent and Young Adult

Podeszwa, David A. MD; DeLaRocha, Adriana MS

Journal of Pediatric Orthopaedics: July/August 2013 - Volume 33 - Issue - p S56–S61
doi: 10.1097/BPO.0b013e31828111f6
Hip Disorders Supplement

The residual deformity of Perthes disease can present with a wide variety of proximal femoral pathomorphology with associated intra- and extra-articular sources of pain. A systematic clinical and radiographic analysis is critical to understanding the deformity and identifying the source of pain. Groin pain and lateral hip pain are the most common complaints but patients can present with buttock, thigh, knee or even low back pain. Each location can suggest a different source of pain. Understanding the potential associated deformities can also help one identify the source of the clinical complaints as intra- or extra-articular. A thorough physical examination of the hip and lower extremities is critical and should include evaluation of the patient standing, supine, prone and in the lateral position. Each examination element can help link the clinical complaint to the underlying proximal femoral deformity. Radiographic evaluation should utilize a standard technique and the initial imaging should include an anteroposterior pelvis, lateral of the proximal femur and false-profile of the hip. Advanced imaging, including computed tomographic scans and gadolinium enhanced arthro-magnetic resonance imaging, can be helpful in delineating the three dimensional deformity and labral and articular cartilage injury. A thorough understanding of all three elements (clinical complaints, physical examination, radiographs) is critical to tailoring a treatment plan for the symptomatic patient with residual Perthes disease.

Department of Orthopaedic Surgery, Texas Scottish Rite Hospital for Children, Dallas, TX

None of the authors received financial support for this study.

The authors declare no conflict of interest.

Reprints: David A. Podeszwa, MD, Department of Orthopaedic Surgery, Texas Scottish Rite Hospital for Children, 2222 Welborn St., Dallas, TX 75219. E-mail:

The residual deformity of Legg-Calvé-Perthes disease (LCPD) in the skeletally mature patient has been recognized as a source of hip pain resulting from intra-articular and extra-articular impingement.1,2 Various treatments have been described to address the pain and deformity in the adolescent and young adult patient population, including femoral head/neck osteochondroplasty, labral repair or debridement, trochanteric advancement, relative femoral neck lengthening, and proximal femoral or acetabular osteotomies.3–11 The use and a thorough understanding of the diagnostic triad (the clinical history, physical examination, and radiographic evaluation) of this patient group, however, are necessary before any surgical treatment is planned. This paper describes the common clinical presentation of mature patients with LCPD and the important components of the physical examination of the hip that should be included in a standard assessment of the LCPD patient. In addition, imaging techniques and frequently used radiographic parameters used in the radiographic evaluation of the LCPD hip are reviewed.

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The clinical presentation of patients with LCPD varies but is commonly similar to that of patients with femoroacetabular impingement (FAI). Patients will commonly complain of the insidious onset of moderate to marked groin pain resulting in substantial activity limitation.12,13 Additional complaints of ipsilateral anterior or posterior thigh, buttock, or knee pain may also be present. Low back pain, not as common in the adolescent population as in the adult population with residual Perthes disease, may be a consequence of gait dysfunction resulting from hip weakness, pain, or decreased range of motion (ROM).

Complaints of functional limitations may also be similar to those with FAI.13 Start-up pain and stiffness, limp, limited walking or running distance, increased symptoms ascending stairs, decreased sitting tolerance, and difficulty donning shoes and/or socks are complaints that may not be readily offered by the patient but will commonly be present when specifically asked.

An understanding of the anatomic abnormalities commonly found in the skeletally mature patient with LCPD is critical to deducing the origin of a patient’s complaints. LCPD may lead to both femoral and acetabular pathology. Femoral pathology may be either intra-articular or extra-articular. Patients with intra-articular pathology may complain of catching or locking of the hip and/or groin pain with activities involving flexion and internal rotation, prolonged sitting/standing, squatting, ascending stairs, and bending down to put on shoes. Patients with extra-articular pathology may have lateral or posterior pain with external rotation (suggests trochanteric-pelvic impingement), a snapping hip (secondary to trochanteric overgrowth) or symptoms consistent with trochanteric bursitis (iliotibial band contracture with or without trochanteric overgrowth), and secondary abductor insufficiency. Acetabular pathology may involve dysplasia, incongruency, or acetabular retroversion. Dysplasia and incongruency can lead to instability that may cause groin pain after upright activities, and acetabular retroversion may lead to FAI with groin pain after activities involving flexion and internal rotation, prolonged sitting/standing, squatting, ascending stairs, or flexing the hip to don shoes and socks.

The chronicity of symptoms may influence the type of complaints. Patients with more recent onset symptoms may complain of stiffness and limited ROM, whereas patients presenting with chronic symptoms typically complain of progressive pain and dysfunction, suggesting a higher likelihood of intra-articular injury.

Localizing the pain is equally as important to determine its etiology. Lateral pain may be indicative of abductor insufficiency, trochanteric impingement, bursitis, or a snapping hip, whereas posterior thigh/buttock pain is more indicative of trochanteric impingement. Groin pain is typically associated with FAI, intra-articular disease, and/or instability.

The evaluation of the organic etiology of the pain described in the clinical history should not be performed without an evaluation of potential psychosocial issues that may result in the exacerbation of a patient’s pain response or the creation of nonorganic pain. Many patients deal with chronic pain, commonly a year or more, that may cause them to miss school, discontinue extra-curricular activities, and become isolated from their peer group. This may result in low self-esteem, anxiety, and/or depression and may have an impact on their pain perception. The effect of other familial stressors (divorce, drug use, financial stress) should not be underestimated. The treating physician should have a high index of suspicion for underlying psychosocial issues and consider a preoperative psychology evaluation as part of a comprehensive plan of care.

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The physical examination provides a basis for the association of clinical complaints to anatomic abnormalities and will help determine the source of pain (intra-articular vs. extra-articular pathology). A thorough and reproducible physical examination is critical at the initial evaluation and each subsequent visit.

The physical examination consists of several components including a standing, supine and prone assessment14 (Table 1). A standing examination should include the determination of a limb length discrepancy (ie, the iliac crests level when standing) and the Trendelenburg test for abductor insufficiency.14 The Trendelenburg test simulates a loaded single-leg stance and test the strength of the abductors to hold the pelvis level. The patient stands with feet shoulder width apart with 1 hip and the ipsilateral knee flexed 45 degree. The patient should hold the position for 30 seconds and the observer looks for pelvic obliquity and the patient leaning over the hip. Observing a patient’s gait from in front and behind (best performed in a hallway 20 to 30 m long) will suggest whether a limp is antalgic (pain causing shortened stride, decreased time in stance phase) or secondary to abductor insufficiency (Trendelenburg gait). Observation of lower extremity rotation and foot progression may be important in planning for lower extremity osteotomies.



The supine examination should include palpation of the greater trochanter, sacroiliac joint, anterior superior iliac spine, ischial tuberosity, and any other site of pain to determine whether pain can be localized to a bony or musculotendonous source. Hip ROM (external/internal rotation, abduction, adduction) and associated pain should be recorded with the hip in full extension and external/internal rotation recorded with the hip flexed 90 degree. The impingement test (hip flexion, adduction, and internal rotation)15 should be routinely performed. Pain associated with this maneuver suggests intra-articular (most commonly labral) pathology. However, it is critical to determine whether the pain associated with the maneuver reproduces the location and quality of the pain felt with daily activities. If it does not, the etiology of the primary pain may not be intra-articular. Flexion, abduction, and external rotation (FABER or Patrick test)14 is used to differentiate between sacroiliac and posterior hip or trochanteric pathology. The hip should be flexed to 45 degree while externally rotating the hip; so, the ipsilateral ankle is placed proximal to the contralateral knee. Attention should be paid to the difference in ROM between hips and the location of pain, particularly posterior to the greater trochanter (extra-articular impingement).

The lateral physical examination, key to identifying extra-articular sources of pain, consists of the tensor fascia lata, gluteus medius, and gluteus maximus contracture tests. The patient is positioned on the unaffected hip with the shoulders at 90 degree to the table. The tensor fascia lata contracture test (Ober test) is performed with the hip and knee in extension, thus placing tension on the tensor fascia lata when the hip is adducted.14 Normally, the patient’s hip should easily adduct past the midline. The gluteus medius contracture test is performed with the hip in neutral flexion-extension and 45 to 90 degree of knee flexion, thus releasing the iliotibial band and placing tension on the gluteus medius with hip adduction. The gluteus maximus contracture test is performed with the shoulders rotated back toward the table with hip flexion and knee extension, thus placing tension on the gluteus maximus with hip adduction.14 Restriction of motion and comparison with the contralateral side should be noted. Abductor strength should be recorded in the lateral position for both hips.

The prone physical examination consists of the femoral anteversion test. Both hips are internally rotated with the knees flexed 90 degree, and the angle between the long axis of the tibia and an imaginary vertical line is recorded. Significant differences in internal rotation are often noted between the supine flexed rotation and prone rotation and may be caused by osseous and/or ligamentous abnormalities.

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Abnormal radiographic findings are not an indication for operative intervention in the asymptomatic or symptomatic patient. All radiographic findings should be correlated with the clinical complaints and physical examination findings. FAI (intra-articular and extra-articular) regardless of the underlying cause is a diagnosis based on history and physical examination supported by radiographic findings.

Plain radiographs are the initial imaging tool for the evaluation of LCPD and should consist of an anteroposterior (AP) pelvic radiograph, false profile of the acetabulum, and a proximal femoral lateral radiograph (Table 2). The use of a standardized technique for the AP pelvic radiograph (standing or supine) is critical. The patient’s lower extremities should be internally rotated 15 degree to correct for femoral anteversion and display the full length of the femoral neck. The tube-to-film distance should be 120 cm, and the beam should be centered on a point midway between the superior border of the pubic symphysis and a line connecting the anterior superior iliac spines.24 Every pelvic radiograph should be scrutinized for tilt and rotation, as it significantly effects the measurement of the various radiographic parameters, especially acetabular retroversion. The coccyx should be directly in line with the pubic symphysis, and the iliac wings, obturator foramina, and radiographic teardrops should be symmetrical in appearance.24 A distance of 1 to 3 cm separating the pubic symphysis and the tip of the coccyx delineates appropriate pelvic inclination. The distance between the pubic symphysis and the sacrococcygeal junction (average 32.3 mm in men, 47.3 mm in women) has also been described as an indicator for accurate pelvic inclination, but the visualization of the sacrococcygeal junction can be difficult to identify.25



The AP radiograph is used to measure the following radiographic parameters: lateral center edge angle (LCEA),16 acetabular index,17 Shenton line, cross-over sign,18–20 ischial spine sign,21 femoral head extrusion index,22 and articulo-trochanteric distance26 (Fig. 1). The normal LCEA is considered >25 degree, whereas <20 degree is considered an indicator of a dysplastic hip, although the center of the aspherical head may be difficult to assess. A hip with an acetabular index <10 degree is considered normal, >10 degree is considered dysplastic, and <0 degree is considered overcovered. Sharp angle, the angle of the acetabular inlet and another measurement of the lateral acetabular coverage, could also be measured but its utility has not been studied in the hip preservation literature. Evaluation of Shenton line in LCPD is also an important radiographic parameter, with <5-mm disruption considered normal and a >5-mm disruption considered abnormal. A disruption in Shenton line suggests instability and/or subluxation. The cross-over sign is a measure of acetabular version, with the anterior and posterior acetabular walls crossing at the lateral margin of the acetabulum in a normal hip.20 Hip flexion contracture causing increased lumbar lordosis and pelvic rotation will lead to misrepresentation of the true acetabular version. Similarly, the ischial spine sign (visualization of the ischial spine medial to the ilioischial line) is a marker of acetabular retroversion20 but may be less affected by pelvic tilt or rotation.27



The false-profile radiograph23 is used to measured the ventral center edge angle of the acetabulum (normal >25 and <20 degree may indicate instability; Fig. 2). The radiograph is obtained with the patient standing and the affected hip against the cassette stand and the pelvis rotated 65 degree relative to the stand. The ipsilateral foot to affected hip is positioned parallel to the cassette stand and the beam centered on the affected hip at a tube-to-film distance of approximately 40 inches (107 cm).24 As with the LCEA, an aspherical femoral head may make the ventral center edge angle difficult to measure.



The choice of lateral radiograph of the proximal femur includes the single frog-leg lateral view,28 Dunn view, or the cross-table lateral29 (Fig. 3), all of which allow for quantification of the head-neck offset ratio, the α-angle, and the sphericity of the femoral head.24,30 The single frog-leg lateral view is obtained with the patient supine and the affected hip abducted 45 degree with the ipsilateral knee flexed 30 to 40 degree and resting against the medial aspect of the contralateral knee. If the hip does not sufficiently abduct or externally rotate secondary to the underlying hip deformity, a bilateral frog-lateral AP pelvic radiograph would result in an inadequate image of the proximal femur. When obtaining a single frog lateral, the patient’s pelvis can be tilted to the effected side to increase the relative abduction and rotation of the hip, thus minimizing the risk of an inadequate image. The Dunn view (45- or 90-degree view) is performed with the patient supine with the hip flexed 45 or 90 degree with the hip abducted 20 degree with neutral rotation.15 The cross-table lateral radiograph is obtained with the patient supine on the x-ray table with the unaffected hip and knee flexed at least 80 degree and the affected hip internally rotated 15 degree to place the femoral neck in profile. The beam is parallel to the table and angled 45 degree to the affected hip.15 Obesity can significantly influence the quality of the radiograph, and the patient may be exposed to higher radiation dose relative to the other lateral images.



Advanced imaging for LCPD includes computed tomography scans,31 magnetic resonance arthrography,32,33 and dGEMRIC (delayed Gadolinium-enhanced magnetic resonance imaging of cartilage) scans.34 Computed tomography scans allow for delineation of the head-neck deformity, sources of extra-articular impingement (i.e. greater and lesser trochanters), and 3-dimensional reconstruction of the affected hip. The added risk associated with the increased radiation exposure31 should be weighed against the benefit of a better understanding of the complex hip deformity. Magnetic resonance arthrography has been proven to be effective in identifying the proximal femoral anatomy, acetabular labral injury, femoral head and/or acetabular cartilage injury, and the 3-dimensional deformity of the hip.35 Radial sequencing (cuts rotating around the femoral neck axis resulting in images perpendicular to the acetabular rim) is critically important in completely assessing the head-neck junction and the labrum in its entire circumference.32,33 dGEMRIC allows direct, qualitative assessment of cartilage matrix biochemistry and may depict the complex damage pattern of hip joint cartilage after LCPD better than other radiographic methods.34

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Adolescent and young adult patients with residual deformity of LCPD are a heterogenous cohort with varying degrees of deformity of the acetabulum and proximal femur. Clearly understanding the patient’s complaints of pain and functional impairment can be the first clue to the anatomic abnormality driving the symptoms. A thorough and systematic physical examination will aid in correlating the patients pain complaints and functional limitations with the underlying anatomic abnormalities. Finally, standardized plain radiographs, with or without advanced imaging, will complete the diagnostic triad that should offer enough information to create a thoughtful and detailed plan to address the patient’s symptoms and hip pathology.

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Perthes disease; clinical presentation; physical examination; radiographic analysis

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