Beyond the femoroacetabular impingement: other atypical causes of hip impingement

Transcription

1 Beyond the femoroacetabular impingement: other atypical causes of hip impingement Poster No.: C-0229 Congress: ECR 2015 Type: Educational Exhibit Authors: N. Arevalo, E. Diez, J. Gredilla Molinero, A. Munoz Hernandez, M. Grande Barez, E. Roa; Madrid/ES Keywords: Athletic injuries, Diagnostic procedure, Education, MR, CT, Conventional radiography, Musculoskeletal soft tissue, Musculoskeletal joint DOI: /ecr2015/C-0229 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 44

2 Learning objectives To give an overview of non-femoroacetabular forms of hip impingement (including ischiofemoral, anterior inferior iliac spine/subspine and iliopsoas impingement) doing a review of recent literature. To discuss the role of imaging in the evaluation of atypical forms of hip impingement and illustrate the main radiologic features which will enable us to suggest a more accurate diagnosis. Page 2 of 44

3 Background Femoroacetabular impingement (FAI) is a well known cause of hip pain, labral tears and early osteoarthritis, and has been extensively reported in the literature over the past decade. The morphological characteristics most commonly associated with FAI include decreased head-neck offset and retroversion of the acetabulum. However, in the last few years, other different forms of hip impingement have been increasingly recognized as a potential cause of hip pain and limited function in young patients. These non-femoroacetabular impingement syndromes include ischiofemoral impingement, anterior inferior iliac spine/subspine impingement and iliopsoas impingement. It is important to diagnose these conditions in order to prevent improper and unnecessary treatments. [1,2,3] Ischiofemoral impingement is due to narrowing of the space between the ischial tuberosity medially and femoral lesser trochanter laterally, with abnormal morphology and/or magnetic resonance imaging signal intensity of quadratus femoris mucle (QFM). [4] Anterior inferior iliac spine or subspine impingement is attributed to abnormal contact between the distal femoral neck and a prominent anterior inferior iliac spine (AIIS) with straight hip flexion. [1,2] Iliopsoas impingement represents a distinct etiology for acetabular labral tears at the atypical anterior location (3 o'clock position), where the iliopsoas tendon crosses the acetabular rim. [5] The etiology, clinical presentation, diagnostic criteria and treatment options for these atypical forms of extra-articular hip impingement are sparsely reported and further validation of clinical and radiologic diagnostic criteria are needed. [1,2,3] The current clinical concepts and the most common imaging findings are summarized in this presentation. Page 3 of 44

4 Findings and procedure details ISCHIOFEMORAL IMPINGEMENT Ischiofemoral impingement is defined by hip pain related to narrowing of the space between the ischial tuberosity-hamstring tendon unit medially and lesser trochanter laterally, with intermittent compression of the quadratus femoris muscle (QFM) and associated edema, tears or fatty replacement. [3,4] Fig. 1 on page 23 Page 4 of 44

5 Fig. 1: Axial proton density-weighted MR image of left hip shows the anatomic relationship of QFM (dotted red line) in the ischiofemoral space. The QFM is a flat and quadrilateral shaped muscle located between the ischial tuberosity medially and femoral lesser trochanter laterally (crossed lines). It arises from the upper part of the lateral border of the ischial tuberosity, just anterior to the hamstring tendon origin (bordered by the yellow line), and inserts at the intertrochanteric crest on the posterior aspect of the proximal femur. Anteriorly, the QFM is bordered by the obturator externus muscle (star) and posteriorly it is bordered by fat and the sciatic nerve (blue arrow). References: References: Radiology, Unidad Central de Radiodiagnóstico, Hospital Infanta Leonor - Madrid/ES Page 5 of 44

6 The ischiofemoral narrowing may be positional, acquired or congenital. Positional factors that may cause ischiofemoral narrowing include lower extremity internal/external rotation, adduction/abduction, and flexion/extension. Congenital ischiofemoral narrowing causes may include a lower ischiopubic ramus, prominent lesser trochanter, larger cross section of the femur at the level of the lesser trochanter, more posteromedial position of the femur, or the common configuration of the female pelvic osseous anatomy (which shows greater width and lesser anteroposterior dimensions when compared to males). Finally, acquired ischiofemoral narrowing may be seen secondary to prior fractures of the lesser trochanter, intertrochanteric valgus osteotomy, expansile bone lesions (eg, osteochondroma), QFM atrophy, enthesophytes extending laterally from the proximal hamstring origin or osteoarthritis changes leading to superomedial migration of the femur. [1,4,6,7] The ischiofemoral narrowing can be evaluated by measuring the following spaces: Ischiofemoral space (IFS): The smallest distance between the lateral cortex of the ischial tuberosity and the medial cortex of the lesser trochanter. Quadratus femoris space (QFS): The smallest space for passage of the QFM bordered by the superolateral surface of the hamstring tendons and the posteromedial surface of the iliopsoas tendon or lesser trochanter. (performing the measurements on axial MRI images through the lesser trochanter). [4,6,7] Fig. 2 on page 24 Page 6 of 44

7 Fig. 2: Axial proton density-weighted MR image of left hip shows normal ischiofemoral space (IFS-blue line) and quadratus femoris space (QFS-red line). References: References: Radiology, Unidad Central de Radiodiagnóstico, Hospital Infanta Leonor - Madrid/ES With the hip in adduction, external rotation and extension, the normal distance between lesser trochanter and ischial tuberosity (IFS) proposal by some authors is about 2.0 cm. The prevalence of a narrowed IFS and QFS in asymptomatic patients is unknown. Page 7 of 44

8 However, two studies have shown that in patients with symptomatic ischiofemoral impingement, the distances of IFS and QFS are significantly reduced compared with control individuals: Symptomatic patients Control patients IFS: 13±5 mm IFS: 23±8 mm QFS: 7±3 mm QFS: 12±4mm IFS: 12.9±3.7 mm IFS: 29.3±5.9 mm QFS: 6.71±2.7 mm QFS: 13.5±4.5 mm Hip in internal rotation [7] Hip in neutral position [6] Some caution is advised in daily practice, because the measurements depend on the degree of hip rotation, adduction and extension during image acquisition. MRI acquisition with hip in external rotation must be avoided as this may lead to overestimation of IFS and QFS narrowing. [3,7] - Clinical presentation more common in women patients affected are usually older than patients with other types of hip impingement, with a mean age of years (although it can affect all ages, ranging from 11 to 77 year) nonspecific chronic pain in the hip, groin and/or buttock without a history of traumatic injury distal radiation of pain to the posterior thigh and knee is not uncommon likely due to irritation of the adjacent sciatic nerve (sciatic radiculopathy symptoms) Fig. 4 on page 25 Fig. 5 on page 26 snapping sensation or locking in the joint there is no specific clinical test on physical examination, although pain may increase with wide range of hip positions: may be reproduced by a combination Page 8 of 44

9 of hip extension, adduction and external rotation or with flexion and internal rotation [1,2,4,6,7] - Diagnosis and imaging findings The diagnosis of ischiofemoral impingement is largely dependent on imaging studies, especially on MR images, even though radiologic findings should be interpreted with caution. It is very important correlate radiologic findings with clinical history and physical examination due to narrowing of IFS, with or without QFM edema or atrophy, may be an incidental finding in asymptomatic patients or severe clinical symptoms are not always related to narrower spaces. In fact, it is not uncommon that patients present with bilateral IFS narrowing with mild QFM edema and unilateral hip pain. On the other hand, symptomatic patients with QFM edema have been observed with normal space measures (although some of these patients may have a traumatic QFM tear rather than impingement). [3,7,8] Plain radiographs of the hip in these patients are usually normal, although chronic osseous changes such as sclerosis and cystic changes of the lesser trochanter and the ischium may be present. [1,4] Fig. 3 on page 24 Page 9 of 44

10 Fig. 3: A 45-year-old man with six month history of right groin. Right hip radiographs views show chronic osseous changes of ischiofemoral impingement, with sclerosis and subcortical cystic changes of the lesser trochanter and the ischium (blue arrow). Axial proton density-weighted fat-suppressed MR image of the same patient shows edema within QFM(curved arrow)and subcortical cystic changes with edema in the ischial tuberosity (thin blue arrow). References: References: Radiology, Unidad Central de Radiodiagnóstico, Hospital Infanta Leonor - Madrid/ES A routine hip or pelvis protocol of MR imaging is the standard method to diagnose ischiofemoral impingement (best seen on axial images). Changes suggestive of ischiofemoral impingement include a reduced IFS and/or QFS with deformity and edema (minor or moderate degree in most patients) or partial tears, centered on QFM belly at the site of maximal impingement, which may be unilateral or bilateral. With increased severity of impingement, edema becomes more severe and Page 10 of 44

11 diffuse and may involve the surrounding soft tissues. [3,4,7] Fig. 3 on page 24 Fig. 4 on page 25 Fig. 5 on page 26 Fig. 6 on page 27 Fig. 4: A 42-years-old woman with a one year history of left hip pain and distal radiation of pain to the posterior knee. Axial CT and MR images (coronal proton density-weighted fat-suppressed, axial T2-weighted fat suppressed and axial T1weighted) demostrate ischiofemoral impingement in left hip with narrowed IFS(blue line in CT), diffuse edema with moderate fatty infiltration of QFM (curved arrow) and mass effect of QFM on sciatic nerve(blue arrow). References: References: Radiology, Unidad Central de Radiodiagnóstico, Hospital Infanta Leonor - Madrid/ES Additional imaging findings present in ischiofemoral impingement that we can find are: edema surrounding the iliopsoas tendon insertion Page 11 of 44

12 edema and tears affecting the hamstring tendons Fig. 5 on page 26 bone marrow edema, sclerosis or cystic change of the ischium/lesser trochanter Fig. 3 on page 24 bursa-like formation Fig. 6 on page 27 or muscle atrophy with fatty infiltration (in patients with long-standing ischiofemoral impingement) Fig. 7 on page 28 [1,3,4,6,7] Differential diagnoses, such as a strain or tear of the quadratus femoris muscle without ischiofemoral impingement must be ruled out by performing a precise clinical history. One morphologic feature that might help in differentiating these entities at MRI is the fact that edema from a tear or strain most commonly occurs at the musculotendinous junction, whereas the muscle edema in ischiofemoral impingement is diffuse or at the site of maximal impingement. The clinical history of acute onset of pain associated with activity or the absence of IFS narrowing lead away from a diagnosis of ischiofemoral impingement. [3,9] -Treatment Nowadays, no definitive treatment strategy for ischiofemoral impingement has been established. The first option is a conservative treatment that includes activity restriction, antiinflammatory medications and rehabilitation exercises. The second option is a ultrasound o CT-guided steroid and/or local anesthetic injection within the ischiofemoral space. Finally, in those patients in whom pain is refractory to conservative treatment, surgical intervention may be considered, with open decompression of the ischiofemoral space by excision of the lesser trochanter. [1,6] ANTERIOR INFERIOR ILIAC SPINE/SUBSPINE IMPINGEMENT Page 12 of 44

13 Anterior inferior iliac spine or subspine impingement is a recent emergent diagnosis caused when the anterior aspect of the femoral head and neck impacts the anterior inferior iliac spine (AIIS) as a result of AIIS hypertrophy, prior avulsion injuries or pelvic osteotomies. The AIIS apophysis arise just above the level of the anterosuperior acetabular rim and is the origin of the direct head of the rectus femoris. [1,2,3,10] Fig. 8 on page 29 Fig. 8: An anteroposterior and frog-leg lateral radiographs showing the localization of AIIS (blue arrow), just above the anterosuperior acetabular rim (red line) with normal appearance. References: References: Radiology, Unidad Central de Radiodiagnóstico, Hospital Infanta Leonor - Madrid/ES It has a variable morphology. Page 13 of 44

14 Hetsroni et al. described a method to classify the AIIS into three morphological types based on the relationship between the distal extension of the AIIS and the anterosuperior acetabular rim: type I, in which there is a smooth ilium wall between the most caudad level of the AIIS and the anterosuperior acetabular rim, without bone prominence Fig. 9 on page 30; type II, in which the AIIS prominence extended to the level of the acetabular rim Fig. 10 on page 31; and type III, in which a prominent AIIS extended distally to the acetabular rim Fig. 11 on page 32. Type II and Type III variants are associated with a decrease in hip flexion and internal rotation and could be involved in the subspine impingement. [11] Prominence of the AIIS with excessive distal and/or anterior extension can be: developmental and seen in association with acetabular retroversion; traumatic, due to prior apophyseal or rectus femoris tendon avulsions, or over-correction after periacetabular osteotomy. Although most patients with an avulsion injury of the AIIS have a good response to conservative treatment, in some patients the inferior displacement of the apophysis can lead to malunion which results in an enlarged AIIS. Repeated contact between this abnormally hypertrophic AIIS and the distal femoral neck, mainly with hip flexion movement, is supposed to be the cause of this form of extraarticular hip impingement secondary to a mechanical conflict. [1,3,12] - Clinical presentation patients are typically years-old with strong male predominance actively involved in sports anterior hip or groin pain that occurs with straight hip flexion or with prolonged hip flexion anterior hip pain aggravated by activities such as sprinting and kicking (eg. soccer) limitation in range of passive hip straight flexion on physical examination tenderness over the AIIS only partial pain relief after intra-articular anesthetic injections [1,2,3,10] - Diagnosis and imaging findings Page 14 of 44

15 Pelvic x-rays and CT scans with 3D reconstruction images play a capital role in the diagnosis of this atypical form of extra-articular hip impingement and are invaluable to the orthopedic surgeon in the preoperative assessment. MR imaging may also demonstrate abnormalities of the AIIS or subspine region, but its role is secondary in this condition Fig. 12 on page 33. Fig. 12: A 28-years-old man with right groin pain during hip flexion and decreased range of motion after sport injury five years ago (soccer player). Anteroposterior pelvis radiographs, 3D CT reconstruction and coronal T1-weighted MR images demonstrate prior avulsion injury of the AIIS with secondary deformity and bony hypertrophy (blue arrow), extending caudad to the level of the anteriorsuperior acetabular rim (type III variant). He was diagnosed with subspine impingement in the right hip. Note that on left side, AIIS is slightly enlarged after prior similar injury (red arrow), but osseous protrusion is smaller (type II variant). Page 15 of 44

16 References: References: Radiology, Unidad Central de Radiodiagnóstico, Hospital Infanta Leonor - Madrid/ES Pelvis or hip radiographs and CT images may demonstrate: AIIS deformity with bony hypertrophy (as a result of prior displaced avulsion fracture) Fig. 12 on page 33 Fig. 14 on page 35 calcified deposits within the proximal portion of the straight head of the rectus femoris tendon (secondary to rectus femoris tendon pathology) Fig. 15 on page 36 extension of AIIS to the level or below the level of the anteriorsuperior acetabular rim Fig. 12 on page 33 Fig. 14 on page 35 [1,3,12] Fig. 12 on page 33 Occasionally cyst in the femoral neck can be found but more distal than those found in FAI. [1,10,12] A case series has shown that concomitant cam type of FAI was present in eight of ten patients with surgically proven subspine impingement [10] and asymptomatic heterotrophic ossification has been described. [2] Consequently, it is essential to assess our radiologic findings within the clinical context of each patients in order to reach a final diagnosis and therefore a more accurate management. -Treatment Surgical management of subspine impingement consists of an arthroscopic decompression of a symptomatic prominent AIIS deformity that results in improved hip motion and hip function. [10] Fig. 12 on page 33 Fig. 13 on page 34 Page 16 of 44

17 Fig. 13: Same patient as in Fig.12 Anteroposterior and frog-leg lateral radiographs views following arthroscopic decompression of the hypertrophic AIIS (blue arrow). Patients was able to return to training and competition at 6 months after the surgery. References: References: Radiology, Unidad Central de Radiodiagnóstico, Hospital Infanta Leonor - Madrid/ES ILIOPSOAS IMPINGEMENT Iliopsoas impingement is a new arthroscopic diagnosis refers to an acetabular labral tears at the anterior location (3-o'clock position) thought to be caused by the iliopsoas tendon. Fig. 16 on page 37 Page 17 of 44

18 Fig. 16: Sagittal T1 fat saturated MR arthrographic image. Schematic drawing on the right hip used to localization of labral tears (clock-face localization). The transverse acetabular ligament (red arrow) is define as 6 o clock (inferior). References: References: Radiology, Unidad Central de Radiodiagnóstico, Hospital Infanta Leonor - Madrid/ES In FAI and other pathological conditions such as trauma, dysplasia, degeneration and hypermobility, labral tears occur mostly in the typical anterosuperior position (1- through 2 o'clock position). [2,13,14] Fig. 16 on page 37 Page 18 of 44

19 In a recent arthroscopic study, Domb and colleagues [13] reported a distinct pattern of labral abnormality, with localized labral damage anteriorly that did not extend to the anterosuperior portion of the acetabulum and that was directly adjacent to the iliopsoas tendon. Several theoretical explanations for this atypical 3-o'clock position labral injury have been proposed: a tight or inflamed iliopsoas tendon causing impingement of the anterior labrum during hip extension, an iliopsoas tendon that has become scarred or adherent to the anterior capsule-labral complex and leads to repetitive traction injury, or a hyperactive iliocapsularis muscle causing a traction injury of the capsularlabral complex. [3,13] This entity is a novel diagnostic entity that differs from: internal coxa saltans, a hip pathology secondary to extra-articular iliopsoas tendon snapping with a painful anterior hip clicking sensation that is reproducible on physical examination iliopsoas impingement after total hip arthroplasty, a hip disorder involving the iliopsoas tendon due to friction against a misaligned or oversized prosthetic acetabular component. - Clinical presentation average age of patients with iliopsoas impingement is years (range, years) with strong female predominance anterior hip or groin pain that gets worse with hip flexion and prolonged sitting a positive impingement test (pain with passive flexion, adduction, and internal rotation) nonspecific focal tenderness over the anterior hip area and iliopsoas tendon at the level of the anterior portion of the joint. [13,14] - Diagnosis and imaging findings Page 19 of 44

20 Iliopsoas impingement may not be clinically suspected because there are no specific clinical or imaging findings to reach this diagnosis, so very often the diagnosis is made at the time of arthroscopic hip surgery. Iliopsoas impingement at hip arthroscopy is diagnosed when there is inflammation, deformation, tearing, or mucoid degeneration of the labrum at the 3-o'clock position, located directly beneath the iliopsoas tendon, with no evidence of any other known cause of labral injury (femoroacetabular impingement, trauma, dysplasia, capsular laxity, or osteoarthritis). There can also be associated focal synovitis. [1,13,14] Although specific imaging criteria are still being refined, a recent study by Blankenbaker and colleagues [14] concludes that, without radiologic evidence of dysplasia or FAI, an isolated anterior acetabular labral tear found at MR arthrography at the 3 o'clock position should suggest the diagnosis of iliopsoas impingement, especially if the tear does not extend above the 2 o'clock position. Other parameters evaluated in this study did not show substantial statistical differences. In a recent study, Aly and colleagues [16] support this affirmation. Fig. 17 on page 38 Fig. 18 on page 39 Page 20 of 44

21 Fig. 18: A 35-years-old woman with left groin pain, especially with the supine and sitting position, nonspecific focal tenderness over the iliopsoas tendon area and a positive impingement test. No radiographic hallmarks of femoroacetabular impingement were presents (not shown). Sagittal and axial oblique T1 fat saturated MR arthrographic images of left hip show a small anterior labral tear (blue arrow) directly beneath the iliopsoas tendón (curved white arrow). This combination of clinical and radiological findings is suggestive of iliopsoas impingement. References: References: Radiology, Unidad Central de Radiodiagnóstico, Hospital Infanta Leonor - Madrid/ES In any case, further research is needed to examine pathologic mechanisms, to establish a causal relationship between abnormalities of the iliopsoas tendon and labral damage and to validate possible radiologic criteria. [1,3] -Treatment Page 21 of 44

22 Surgical management of iliopsoas impingement includes labral debridement or repair combined with tenotomy of the iliopsoas tendon at the level of the acetabulum. [14,15] Suggesting this diagnosis preoperatively can be very helpful because this condition may go unrecognized at time of hip arthroscopy if it is not suspected. Page 22 of 44

23 Images for this section: Fig. 1: Axial proton density-weighted MR image of left hip shows the anatomic relationship of QFM (dotted red line) in the ischiofemoral space. The QFM is a flat and quadrilateral shaped muscle located between the ischial tuberosity medially and femoral lesser trochanter laterally (crossed lines). It arises from the upper part of the lateral border of the ischial tuberosity, just anterior to the hamstring tendon origin (bordered by the yellow line), and inserts at the intertrochanteric crest on the posterior aspect of the proximal femur. Anteriorly, the QFM is bordered by the obturator externus muscle (star) and posteriorly it is bordered by fat and the sciatic nerve (blue arrow). Page 23 of 44

24 References: Radiology, Unidad Central de Radiodiagnóstico, Hospital Infanta Leonor - Madrid/ES Fig. 2: Axial proton density-weighted MR image of left hip shows normal ischiofemoral space (IFS-blue line) and quadratus femoris space (QFS-red line). References: Radiology, Unidad Central de Radiodiagnóstico, Hospital Infanta Leonor - Madrid/ES Page 24 of 44

25 Fig. 3: A 45-year-old man with six month history of right groin. Right hip radiographs views show chronic osseous changes of ischiofemoral impingement, with sclerosis and subcortical cystic changes of the lesser trochanter and the ischium (blue arrow). Axial proton density-weighted fat-suppressed MR image of the same patient shows edema within QFM(curved arrow)and subcortical cystic changes with edema in the ischial tuberosity (thin blue arrow). References: Radiology, Unidad Central de Radiodiagnóstico, Hospital Infanta Leonor - Madrid/ES Page 25 of 44

26 Fig. 4: A 42-years-old woman with a one year history of left hip pain and distal radiation of pain to the posterior knee. Axial CT and MR images (coronal proton density-weighted fat-suppressed, axial T2-weighted fat suppressed and axial T1-weighted) demostrate ischiofemoral impingement in left hip with narrowed IFS(blue line in CT), diffuse edema with moderate fatty infiltration of QFM (curved arrow) and mass effect of QFM on sciatic nerve(blue arrow). References: Radiology, Unidad Central de Radiodiagnóstico, Hospital Infanta Leonor - Madrid/ES Page 26 of 44

27 Fig. 5: A 69-years-old woman with right buttock pain radiating distally to posterior aspect of the leg. Axial T1 and proton density-weighted fat-suppressed and coronal T2-weighted fat-suppressed MR images of right hip show ischiofemoral impingement with severe diffuse edema and partial tear of QFM (curved arrow), mass effect of QFM on sciatic nerve (white circle) and tendinopathy of hamstring tendons(red arrow). Mild edema and fatty infiltration of left QFM is also noted. References: Radiology, Unidad Central de Radiodiagnóstico, Hospital Infanta Leonor - Madrid/ES Page 27 of 44

28 Fig. 6: A 14-years-old woman flamenco-dancer, apparently without symptomatic complaints. Axial T1 and proton density-weighted fat-suppressed MR images show, as incidental findings, severe diffuse edema with enlagement and a bursalike formation within right QFM (blue arrow);qfs narrowed and mild edema of QFM in the left hip is also noted. References: Radiology, Unidad Central de Radiodiagnóstico, Hospital Infanta Leonor - Madrid/ES Page 28 of 44

29 Fig. 7: A 66-years-old woman with long history of bilateral hip pain. Axial proton density-weighted and proton density-weighted fat-suppressed MR images show chronic ischiofemoral impingement signs, with narrowed IFS (blue line) and severe fatty infiltration of QFM in both hips. Mild QFM edema (curved arrow) and mild tendinopathy of hamstring tendons (red arrow) is also noted in the right hip. References: Radiology, Unidad Central de Radiodiagnóstico, Hospital Infanta Leonor - Madrid/ES Page 29 of 44

30 Fig. 8: An anteroposterior and frog-leg lateral radiographs showing the localization of AIIS (blue arrow), just above the anterosuperior acetabular rim (red line) with normal appearance. References: Radiology, Unidad Central de Radiodiagnóstico, Hospital Infanta Leonor - Madrid/ES Page 30 of 44

31 Fig. 9: 3D CT reconstruction views of the pelvis showing a smooth ilium wall (red arrow) between the caudad level of the AIIS (blue arrow) and the anterosuperior acetabular rim in both hips. Type I AIIS variant. References: Radiology, Unidad Central de Radiodiagnóstico, Hospital Infanta Leonor - Madrid/ES Page 31 of 44

32 Fig. 10: 3D CT reconstruction views of the pelvis where both AIIS (blue arrow) sit just at the level of the acetabular rim (red arrow) and appears as a ''rooflike'' prominence over the hip. Type II AIIS variant. References: Radiology, Unidad Central de Radiodiagnóstico, Hospital Infanta Leonor - Madrid/ES Page 32 of 44

33 Fig. 11: 3D CT reconstruction views of the pelvis showing the prominent AIIS (blue arrow) in the right hip extending caudad to the level of the anteriorsuperior acetabular rim (red arrow). Type III AIIS variant. References: Radiology, Unidad Central de Radiodiagnóstico, Hospital Infanta Leonor - Madrid/ES Page 33 of 44

34 Fig. 12: A 28-years-old man with right groin pain during hip flexion and decreased range of motion after sport injury five years ago (soccer player). Anteroposterior pelvis radiographs, 3D CT reconstruction and coronal T1-weighted MR images demonstrate prior avulsion injury of the AIIS with secondary deformity and bony hypertrophy (blue arrow), extending caudad to the level of the anteriorsuperior acetabular rim (type III variant). He was diagnosed with subspine impingement in the right hip. Note that on left side, AIIS is slightly enlarged after prior similar injury (red arrow), but osseous protrusion is smaller (type II variant). References: Radiology, Unidad Central de Radiodiagnóstico, Hospital Infanta Leonor - Madrid/ES Page 34 of 44

35 Fig. 13: Same patient as in Fig.12 Anteroposterior and frog-leg lateral radiographs views following arthroscopic decompression of the hypertrophic AIIS (blue arrow). Patients was able to return to training and competition at 6 months after the surgery. References: Radiology, Unidad Central de Radiodiagnóstico, Hospital Infanta Leonor - Madrid/ES Page 35 of 44

36 Fig. 14: A 16-years-old woman soccer player with right groin pain since four month. On physical examination she had tenderness over the AIIS and limitation of passive hip straight flexion. Axial, sagittal CT and 3D TC reconstruction images demonstrate an avulsion injury of AIIS apophysis in right hip (blue arrow) with bony hypertrophy protruding inferiorly below the level of the anteriorsuperior acetabular rim (red line in sagittal view) (type III variant). She was diagnosed with subspine impingement in right hip. On left side, the AIIS is slightly enlarged after similar injury, but osseous protrusion (red arrow) is much smaller (type II variant). References: Radiology, Unidad Central de Radiodiagnóstico, Hospital Infanta Leonor - Madrid/ES Page 36 of 44

37 Fig. 15: A 43-year-old man with long-term right hip pain and progressive limitation of activity. Anteroposterior pelvis and frog-leg lateral radiographs of the right hip and 3D CT reconstruction images demonstrate a curvilinear calcification (blue arrow) very close to the AIIS, representing calcified deposits within the rectus femoris tendon as a result of old injury. References: Radiology, Unidad Central de Radiodiagnóstico, Hospital Infanta Leonor - Madrid/ES Page 37 of 44

38 Fig. 16: Sagittal T1 fat saturated MR arthrographic image. Schematic drawing on the right hip used to localization of labral tears (clock-face localization). The transverse acetabular ligament (red arrow) is define as 6 o clock (inferior). References: Radiology, Unidad Central de Radiodiagnóstico, Hospital Infanta Leonor - Madrid/ES Page 38 of 44

39 Fig. 17: A 24-years-old woman with right hip and groin pain, nonspecific tenderness over the anterior hip area and without radiographic hallmarks of femoroacetabular impingement (not shown). Axial oblique and sagittal T1 fat saturated MR arthrographic images of right hip demonstrate a small localized anterior labral tear (blue arrow)at 3 o'clock position, directly adjacent to iliopsoas tendón (curved white arrow). This combination of clinical and radiologic findings is suggestive of iliopsoas impingement. References: Radiology, Unidad Central de Radiodiagnóstico, Hospital Infanta Leonor - Madrid/ES Page 39 of 44

40 Fig. 18: A 35-years-old woman with left groin pain, especially with the supine and sitting position, nonspecific focal tenderness over the iliopsoas tendon area and a positive impingement test. No radiographic hallmarks of femoroacetabular impingement were presents (not shown). Sagittal and axial oblique T1 fat saturated MR arthrographic images of left hip show a small anterior labral tear (blue arrow) directly beneath the iliopsoas tendón (curved white arrow). This combination of clinical and radiological findings is suggestive of iliopsoas impingement. References: Radiology, Unidad Central de Radiodiagnóstico, Hospital Infanta Leonor - Madrid/ES Page 40 of 44

41 Conclusion Hip-groin pain is a day-to-day clinical problem, and it may be due to many causes. Although less common than classic femoroacetabular impingement, other atypical forms of hip impingement (including ischiofemoral, anterior inferior iliac spine/subspine and iliopsoas impingement) have been recently identified as a potential cause of hip pain, especially in young nonarthritic patients. Knowledge of their clinical features and radiological findings will enable us to suggest a more specific diagnosis and therefore a more accurate management of these conditions can be achieved. Page 41 of 44

42 Personal information Page 42 of 44

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