Beyond the Bump: The Spectrum of Extra-articular Pathology in Hip MRI for Clinical Femoroacetabular Impingement Poster No.: C-2239 Congress: ECR 2012 Type: Authors: Keywords: DOI: Educational Exhibit K. L. Mutiso, I. Khan, J. Kumaraguru, L. M. Meacock, D. A. Elias; London/UK Trauma, Structured reporting, Education, MR, Musculoskeletal joint 10.1594/ecr2012/C-2239 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. www.myesr.org Page 1 of 23
Learning objectives 1. To review the prevalence of extra-articular pathologies encountered in MRI imaging of patients referred with clinical femoroacetabular impingement. 2. To review the MRI appearances of the spectrum of extra-articular pathologies commonly encountered in patients with groin pain. Page 2 of 23
Background Femoroacetabular Impingement (FAI) is a structural abnormality of the bony acetabulum or proximal femur which, when combined with terminal or rigorous hip motion results in repetitive collisions which damage the labrum and cartilage at the acetabular rim. It is a major cause of early osteoarthritis in the hip. Imaging features are well recognised on conventional radiographs and cross sectional imaging. 1 2 Types of FAI are described: 1. Cam Impingement - the femoral cause of FAI where there is an abnormal head-neck offset with a resulting bony bump at the anterolateral femoral neck (fig. 1 & 2) 2. Pincer impingement - the acetabular cause of FAI where there is over coverage of the acetabular cup around the femoral head (fig. 3) MRI imaging is useful in identifying labral tears and hyaline cartilage injury, which are associated with impingement (fig. 4) Studies have shown that many of the structural imaging correlates of FAI are common and may be seen in asymptomatic individuals. 2 MRI studies of patients with clinical FAI may show other potential causes of hip and groin pain. We therefore set out to review the spectrum and prevalence of extra-articular pathologies identified in a group of patients referred for MRI with a clinical diagnosis of FAI. Page 3 of 23
Images for this section: Fig. 1: Cam morphology: There is an abnormal head-neck offset with a resulting bony bump at the anterolateral femoral neck. Page 4 of 23
Fig. 2: Cam morphology: There is an abnormal head-neck offset with a resulting bony bump at the anterolateral femoral neck Page 5 of 23
Fig. 3: Pincer impingement: There is over coverage of the acetabular cup around the femoral head. Page 6 of 23
Fig. 4: Coronal T1 weighted MR arthrogram with fat suppression shows triangular labrum avulsed from acetabular attachment. A fluid cleft is identified through labral detachment. Page 7 of 23
Imaging findings OR Procedure details Methods & Materials We reviewed the non-arthrographic MR imaging findings of all patients with clinically diagnosed femoroacetabular impingement referred to our department for MRI between 2008 to 2011. Scans were included where there was a clinical diagnosis of hip impingement with no previous history of hip surgery, hip trauma, post-traumatic deformity or arthropathy. All MRIs were performed on a 1.5 Tesla Siemens Avanto. Results A total of 102 patient's MRI scans fulfilled the criteria of which 62 were of female patients and 40 were of male patients. The average age was 40.8 yrs with an age range of 14 to 66 yrs. Features supporting the clinical diagnosis of femoroactabular impingement were seen in 49% (50/102) of patients.cam morphology was the most common feature encountered in this group of patients (Tab. 1). 28 % (14/50) of patients with features of FAI also had other extra-articular findings, the most common of which was trochantaric bursitis/gluteus medius tendinopathy 12% (6/50) (Tab. 2). 43.1 % (44/102) of patients had other pathologies identified with no features of femoraacetabular impingement of which 95.5 % (42/44) were extra-articular pathologies as outlined in Table 3. 7.8 % (8/102) patients had completely normal MRIs with no features of FAI or any other abnormality seen to explain the cause of their hip pain. Feature supporting clinical diagnosis of FAI Cammorphology Pincer morphology Percentage of patients with features of FAI 76 % (38/50) 14 % (7/50) Page 8 of 23
Camand Pincer morphology 10 % (5/50) Labral Tears 12 % (6/50) Table 1. Features supporting clinical diagnosis of FAI seen in 49% (50/102) of the study population. Extra-articular pathology in addition to features supporting clinical diagnosis of FAI Percentage of patients with features of FAI Tronchanteric bursitis/glut medius tendinopathy Osteitis Pubis Common hamstring strain Ileopsoas Bursitis Obturator externus Bursitis Adductor origin Strain Sacroilitis Inguinal Hernia Femoral neck stress fracture 12 % (6/50) 6 % (3/50) 6 % (3/50) 4 % (2/50) 4 % (2/50) 2 % (1/50) 2 % (1/50) 2 % (1/50) 2 % (1/50) Table 2. The various other pathologies present in addition to features of FAI. Other pathologies with no MRI features of FAI Trochanteric bursitis/glut medius tendinopathy Osteitis pubis Hamstring origin Strain Nerve root impingement Adductor origin Sprain Sacroilitis Ischiofemoral Impingement Femoral neck stress fracture Percentage of patients with other pathologies 47.7 % (21/44) 15.9 % (7/44) 13.6% (6/44) 9.1% (4/44) 6.8 % (3/44) 6.8 % (3/44) 4.5 % (2/44) 2.3 % (1/44) Page 9 of 23
Ileopsoas bursitis Inguinal hernia Developmental Dysplasia of the Hip Avascular necrosis 2.3 % (1/44) 2.3 % (1/44) 2.3% (1/44) 2.3 % (1/44) Table 3. The other pathologies identified in the absence of features of FAI seen in 43.1% (44/102) of the study population. Discussion: Our study has demonstrated a wide range of extra-articular pathologies prevalent in the evaluation of MRI's performed on patients with a clinical diagnosis of femoroacetabular impingement. Gluteus medius tendinopathy and trochanteric bursitis were considered to be the same entity for the purpose of this study and this was the most common extra - articular finding. The diagnosis of femoroacetabular impingement should be made clinically and whilst MR imaging correlates of impingement may be identified they may not necessarily be a primary cause of pain. Our study has demonstrated that extra-articular pathologies are commonly identified in patients with a clinical diagnosis of impingement and relevance of these findings to groin pain in an individual patient needs to be considered. It is possible also that patients with impingement may have altered biomechanics, which in itself could predispose to other pathologies such as tendon sprains in the region of an injured hip. 3 We present a pictorial review of the MRI features of some of the extra-articular pathologies encountered in our study (Fig. 5-14) Page 10 of 23
Images for this section: Fig. 5: Trochanteric bursitis/gluteus Medius tendinopathy:coronal STIR image showing thickening and hyperintensity of the right gluteus medius at its tendon insertion and fluid in the gluteus maximus bursa. Page 11 of 23
Fig. 6: Rectus Femoris tendinopathy:axial STIR image showing fluid between the right indirect tendon and the acetabulum. Page 12 of 23
Fig. 7: Common Hamstring tendon origin tendinopathy: Axial STIR image showing high signal at the left ischial tuberosity and within the hamstring tendon at its insertion. Page 13 of 23
Fig. 8: Ileopsoas Bursitis: Axial STIR image showing high signal fluid surrounding the left ileopsoas muscle, anterior to the hip. Page 14 of 23
Fig. 9: Osteitis pubis: Axial STIR image showing juxta-articular pubic bone marrow oedema and slight irregularity of the pubic symphsis. Page 15 of 23
Fig. 10: Adductor tendon strain: Coronal STIR image showing high signal oedema at the right adductor longus insertion and associated periosteitis. Page 16 of 23
Fig. 11: Ischiofemoral Impingement: Axial STIR image showing high signal oedema in the right quadratus femoris muscle and narrowing of the ischiofemoral space. Page 17 of 23
Fig. 12: Femotral neck stress fracture: Coronal STIR image showing a low signal fracture line extending from the cortex of the left femoral neck with surrounding high marrow signal at the femoral neck. Page 18 of 23
Fig. 13: Inguinal Hernia: Coronal STIR image demonstrating a right sided indirect inguinal hernia. Small bowel loops are contained within the hernia. Page 19 of 23
Fig. 14: Nerve Root Impingement: Coronal STIR MRI demonstrating a normal right hip but with a neurofibroma of the right L4 nerve root. Page 20 of 23
Conclusion Conclusion: Clinical symptoms and signs are essential to the diagnosis of FAI and other impingement syndromes. Imaging abnormalities alone are not sufficient to make the diagnosis of FAI. A wide spectrum of extra-articular findings are frequently encountered in the MRI evaluation of patients with a clinical diagnosis of impingement. Page 21 of 23
Personal Information Dr Kavulani. L. Mutiso MB ChB MRCP FRCR RadiologyTrainee - Subspeciality training in Musculoskeletal Radiology Department of Diagnostic Imaging Kings College Hospital, London, UK Dr Imran Khan MBBS MRCS FRCR Radiology Trainee - Subspeciality training in Musculoskeletal Radiology Department of Diagnostic Imaging Kings CollegeHospital, London, UK Dr Janani Kumaraguru MB ChB Radiology Trainee Department of Diagnostic Imaging Kings College Hospital, London, UK Dr Lisa M. Meacock MB ChB MRCS FRCR Consultant Musculoskeletal Radiologist Department of Diagnostic Imaging Kings College Hospital, London, UK Dr David A. Elias MB ChB MRCP FRCR Consultant Musculoskeletal Radiologist Department of Diagnostic Imaging Kings College Hospital, London, UK Page 22 of 23
References 1. Tannast M, Siebenrock K A, Anderson S E. Femoroacetabular Impingement: Radiographic Diagnosis - What the Radiologist Should Know. AJR Am J Roentgenol 2007 ; 188 ( 6 ): 1540-1552. 2. Palmar W E. FemoroacetabularImpingement: Caution Is Warranted in Making Imaging based Assumptions and Diagnoses Radiology: Volume 257: Number 1-October 2010. 3. Standaert C J, Manner P A, Herring S A. Expert opinion andcontroversies in musculo-skeletal and sports medicine: femoroacetabular impingement.arch Phys Med Rehabil 2008;89:890-3. 4. Torriani M, Suoto S C L, Thomas B J, Quellette H, Bradella M A Ischiofemoral Impingement Syndrome: An Entity with Hip Pain and Abnormalities of the the Quadratus Femoris Muscle. AJR July 2009 vol. 193 no. 1 186-19. Page 23 of 23