Ana Canga

Anatomy, Biomechanics, Imaging, and Management of Ligamentum Teres Injuries

The ligamentum teres has traditionally been viewed as an embryonic remnant with no role in the biomechanics or vascularity of adult hips. However, the ligamentum teres is a strong intraarticular ligament that is anatomically and biochemically similar to the anterior cruciate ligament of the knee. It is composed of two bands that originate from the acetabular transverse ligament and the pubic and ischial margins of the acetabular notch. Among other functions, the ligamentum teres is an important stabilizer of the hip, particularly in adduction, flexion, and external rotation. Abnormalities of the ligamentum teres account for 4%-15% of sports-related injuries and should be considered in the differential diagnosis of patients with hip pain. Lesions of the ligamentum teres include partial or complete traumatic tears, degenerative tears, avulsion fractures of the ligament at its insertion into the fovea capitis femoris, and a congenital absence of the ligament. Magnetic resonance arthrography and computed tomographic arthrography are the preferred modalities for precise preoperative diagnosis of ligamentum teres injuries and may be used to rule out other associated intraarticular injuries. Treatment of these lesions is still evolving; at present, treatment of most injuries is limited to arthroscopic débridement.

Emerging topics on the hip: Ligamentum teres and hip microinstability

Microinstability and ligament teres lesions are emergent topics on the hip pathology. These entities are an increasingly recognized cause of persistent hip pain and should be considered in the differential diagnosis of the patient with hip pain. Conventional (non-arthrographic) CT and MR have a very limited role in the evaluation of these entities. CTa and MRa have emerged as the modalities of choice for pre-operative imaging of ligamentum teres injuries and microinstability. To date, pre-operative imaging detection of these pathologies is not widespread but with appropriate imaging and a high index of suspicion, preoperative detection should improve. This article discusses current concepts regarding anatomy, biomechanics, clinical findings, diagnosis and treatment of ligament teres lesions and microinstability.

Deep gluteal syndrome: anatomy, imaging, and management of sciatic nerve entrapments in the subgluteal space

Deep gluteal syndrome (DGS) is an underdiagnosed entity characterized by pain and/or dysesthesias in the buttock area, hip or posterior thigh and/or radicular pain due to a non-discogenic sciatic nerve entrapment in the subgluteal space. Multiple pathologies have been incorporated in this all-included “piriformis syndrome,” a term that has nothing to do with the presence of fibrous bands, obturator internus/gemellus syndrome, quadratus femoris/ischiofemoral pathology, hamstring conditions, gluteal disorders and orthopedic causes. The concept of fibrous bands playing a role in causing symptoms related to sciatic nerve mobility and entrapment represents a radical change in the current diagnosis of and therapeutic approach to DGS. The development of periarticular hip endoscopy has led to an understanding of the pathophysiological mechanisms underlying piriformis syndrome, which has supported its further classification. A broad spectrum of known pathologies may be located nonspecifically in the subgluteal space and can therefore also trigger DGS. These can be classified as traumatic, iatrogenic, inflammatory/infectious, vascular, gynecologic and tumors/pseudo-tumors. Because of the ever-increasing use of advanced magnetic resonance neurography (MRN) techniques and the excellent outcomes of the new endoscopic treatment, radiologists must be aware of the anatomy and pathologic conditions of this space. MR imaging is the diagnostic procedure of choice for assessing DGS and may substantially influence the management of these patients. The infiltration test not only has a high diagnostic but also a therapeutic value. This article describes the subgluteal space anatomy, reviews known and new etiologies of DGS, and assesses the role of the radiologist in the diagnosis, treatment and postoperative evaluation of sciatic nerve entrapments, with emphasis on MR imaging and endoscopic correlation.

MR and CT Arthrography of the Wrist

The study of the wrist represents a major diagnostic challenge because of its complex anatomy and the small size of individual structures. Recent advances in imaging techniques have increased our diagnostic capabilities. However, 3T magnets, multichannel specific wrist coils, and new MRI sequences have not restricted the indications of arthrographic imaging techniques (CT arthrography and MR arthrography). Distension of the different wrist compartments at CT arthrography and MR arthrography significantly improves the diagnostic accuracy for triangular fibrocartilage (TFC) complex injuries and carpal instability. Dedicated multichannel wrist coils are essential for an adequate study of the wrist, but the placement of these coils and the positioning of the wrist are also important for proper diagnosis. The development of dynamic multislice CT studies allows a diagnostic approach that combines dynamic information and the accurate assessment of ligaments and the TFC complex. New advances in arthroscopy have changed the anatomical description of the TFC with a functional division in the proximal and distal TFC complex, and they have allowed a better characterization of lesions of the TFC complex with subclassification of Palmer 1B and 1D lesions and description of new lesions not included in the Palmer classification, such as capsular injuries.

MR Arthrography of the Ankle: Indications and Technique

MR arthrography has become an important tool for the assessment of a variety of ankle disorders. MR arthrography permits more sensitive imaging of suspected intra-articular pathology in cases in which conventional MR imaging is either insufficient or inadequate for diagnosis or treatment planning. The main indications for MR arthrography are the evaluation of ligamentous injuries, impingement syndromes, cartilage lesions, osteochondral lesions of the talus, loose bodies, and several synovial joint disorders. Indirect MR arthrography can be a useful adjunct to conventional MR imaging and may be preferable to direct MR arthrography in those cases in which an invasive procedure is contraindicated or image guidance is not available.

MRI of the Quadratus Femoris Muscle: Anatomic Considerations and Pathologic Lesions

OBJECTIVE The purpose of this review is to describe the gross anatomic and MRI appearance of the quadratus femoris muscle and the MRI appearance of common lesions of the quadratus femoris. CONCLUSION Lesions of the quadratus femoris have been implicated as a cause of hip pain. It therefore is important to be familiar with the anatomy of the quadratus muscle and to be able to diagnose the causes of abnormal signal intensity in the quadratus femoris, which include tears and impingement.

Elbow Synovial Fold Syndrome

OBJECTIVE The purpose of this article is to review the embryologic development, anatomy, and histology of the synovial plicae of the elbow. The pathophysiologic features, clinical manifestations, imaging findings, and treatment of elbow synovial fold syndrome will also be reviewed. CONCLUSION Elbow synovial fold syndrome is an uncommon entity that is often confused with lateral epicondylitis. Knowledge of the clinical and imaging diagnosis of this entity is essential for the appropriate management of patients.

Imaging Findings of Lower Limb Apophysitis

OBJECTIVE The objective of this article is to present a comprehensive review of apophysitis of the lower limb regarding anatomy, physiopathology, clinical findings, differential diagnosis, and imaging features with special emphasis on MRI. CONCLUSION Apophysitis, which is inflammation of the traction epiphysis resulting from chronic trauma, is a common abnormality that affects the growing child. Understanding the physiopathology of apophysitis is essential for a precise diagnosis on MRI. Accurate identification of key MRI features of this entity may prevent misdiagnosis and inappropriate management of apophysitis.

Pharyngeal branchial cyst: magnetic Resonance findings

An unusual case of pharyngeal cyst in a 25-year-old man studied by Magnetic Resonance (MR) is described. Anatomic location and pathological findings indicated the second branchial pouch origin.

Evaluation and management of ischiofemoral impingement: a pathophysiologic, radiologic, and therapeutic approach to a complex diagnosis

Ischiofemoral impingement syndrome (IFI) is an underrecognized form of atypical, extra-articular hip impingement defined by hip pain related to narrowing of the space between the ischial tuberosity and the femur. The etiology of IFI is multifactorial and potential sources of ischiofemoral engagement include anatomic variants of the proximal femur or pelvis, functional disorders as hip instability, pelvic/spinal instability, or abductor/adductor imbalance, ischial tuberosity enthesopathies, trauma/overuse or extreme hip motion, iatrogenic conditions, tumors and other pathologies. Magnetic resonance imaging (MRI) is the diagnostic procedure of choice for assessing IFI and may substantially influence patient management. The injection test of the ischiofemoral space (IFS) has both a diagnostic and therapeutic function. Endoscopic decompression of the IFS appears useful in improving function and diminishing hip pain in patients with IFI but conservative treatment is always the first step in the treatment algorithm. Because of the ever-increasing use of advanced MRI techniques, the frequent response to conservative treatment, and the excellent outcomes of new endoscopic treatment, radiologists must be aware of factors that predispose or cause IFI. In addition, focused treatment in these conditions is often more important than in secondary impingement. In this article, we briefly describe the anatomy of the IFS, review the clinical examination and symptoms, assess the diagnostic imaging criteria and pathophysiological mechanisms, and develop an understandable classification of IFI, with particular focus on its etiology, predisposing factors, and associated musculoskeletal abnormalities. We also assess the role of the radiologist in the diagnosis, treatment, and preoperative evaluation of both primary and secondary IFI.