identifying inguinal hernias, adductor and hamstring pathology, and for diagnosing labral tears. Although radiographs are initially performed, the major imaging modalities are ultrasound and MRI. n Ultrasound: Ultrasound is especially useful in diagnosing hernias. Inguinal and spigelian hernias can be accurately diagnosed this way. The hernia is visualised highly accurately when the patient performs the Valsalva manoeuvre (24). Ultrasound can identify effusions within the hip but has limited use in further assessment. Tendon and muscle pathology around the hip can be seen to a variable degree and further evaluation by MRI may be needed. Trochanteric bursitis is a common indication for ultrasound. Ultrasound-guided injections are also performed in the hip and bursa (15). n Magnetic resonance imaging: MRI provides an overview of the hip and thigh, and muscle tears and haematomas are easily identified. Athletic pubalgia is a common indication for MRI imaging in athletes. It is caused by a combination of factors that result in musculotendinous injuries, leading to pubic symphysis instability. A large-field of view combined with high-resolution imaging of the pubic symphysis is an excellent way to assess this condition. The MRI localises the injury and provides information on its severity (25). Fig. 5 shows a typical scan obtained by MRI. n MR arthrography: MR arthrography of the hip identifies labral tears with a high degree of accuracy. The site of the tear can be localised and any predisposing aetiology can be identified (26–28).

Imaging the knee joint Imaging of the knee in sports-related injuries is common. n Plain radiographs: Standard radiographs of the knee include the frontal and lateral views. Weight- bearing and so-called “sky-line” views to assess the patellofemoral joint are commonly requested. Fractures patterns often hint at associated soft tissue injuries. For example, capsular avulsion fractures, eponymously named Segond fractures, are associated with anterior cruciate ligament ruptures. n Computerised tomography: CT of the knee is mainly undertaken for surgical planning, although in the past CT arthrography was used to look at

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the menisci. n Ultrasound: This is a focused investigation to assess superficial soft tissues such as the collaterals, the quadriceps muscles and tendons and bursitis around the knee (14,15). It is the diagnostic imaging mode of choice for patellar tendonopathy and soft tissue mass lesions. It is also of value in guiding therapy. n Magnetic resonance imaging: MRI is the main modality for imaging injuries of the knee. It can assess the bones and menisci, cruciates and collaterals, and the muscles around the knee and articular cartilage. Specific patterns of bone bruising, meniscal injuries and cruciate and collateral tears can be seen and relate to various injuries (29,30). MRI also allows the severity of the injury to be determined and provides good pre-operative planning. Although arthroscopy has been held as the gold standard for assessing the knee joint, MRI has comparable sensitivities and specificities, plus there is no need for an invasive procedure (4). See Fig. 6 for an MRI image of the meniscus. n MR arthrography: MRI has low accuracy in post-meniscectomy knees so MR arthrography is now being performed to fulfil this role (17,31,32).

Imaging the ankle and foot The ankle and hind-foot joints are under immense forces in athletes. It is not surprising that these joints are often injured. The main problems seen are tendinous and ligamentous trauma, osteochondral defects, chronic ankle pain syndromes, and ankle instability. n Plain radiographs: Although initial imaging is with plain radiographs, the majority of abnormalities require modalities that can assess soft tissues. These are ultrasound and MRI. n Ultrasound: Ultrasound is performed to look at the tendons and ligament – the Achilles tendon, the peroneal tendons, the posterior tibial tendon and the lateral ligament complex. As ultrasound is a dynamic investigation, some of the clinical examinations, such as the calf squeeze test in Achilles tendon ruptures, are repeated on ultrasound (15). n Magnetic resonance imaging: This provides an accurate overview of the ankle joint. The common indications are chronic ankle and hind-foot pain, ankle instability and diagnosis of osteochondral defects. Different

BE DETRIMENTAL TO AN ATHLETE’S HEALTH AND TO HIS OR HER CAREER

patterns of bony and soft tissue oedema are associated with specific ankle and foot pathology (33,34).

IMAGE-GUIDED THERAPIES Image-guided therapies are used extensively in musculoskeletal interventions (Box 3).

Fluoroscopy

The first applications involved joint injections under fluoroscopy; they are still used commonly today. Fluoroscopic guidance is also used to perform: n Arthrograms of the hip, shoulder and wrist n Steroid injection into joints and synchondroses.

Computerised tomography CT-guided injections have become very popular, because CT gives more information about both depth and direction. CT is used in spinal injections such as: n Facet joint injections n Nerve root blocks. Its main limitations are the time

taken to perform the injection and the exposure of patients to a dose of radiation.

Ultrasound Ultrasound-guided injections have a large role in musculoskeletal interventions. The relative ease of access combined with real-time observations means that this has become the modality of choice for image-guided therapy. Subacromial bursal injections and aspirations of effusions and abscesses are the commonest indications. Ultrasound-

BOX 3: MODALITIES FOR DELIVERING IMAGE- GUIDED THERAPIES

n Fluoroscopy n Computerised tomography n Ultrasound n MRI

sportEX medicine 2010;44(Apr):18-23

TREATMENT ON IMAGING FINDINGS ALONE CAN