Ultrasound of lower limb sports injuries

Abstract

Musculoskeletal ultrasound utilises high-frequency linear transducers to produce high-resolution images of soft tissue structures. It is an increasingly useful tool in the assessment of both acute and chronic musculoskeletal injuries; it is relatively cheap, portable and can be used to facilitate targeted injections. In this review paper, we aim to provide a summary on the normal and abnormal appearances of skeletal tissue in the setting of acute and chronic lower limb sporting injuries.

Keywords: Ultrasound; injuries; lower limb; sports.

Figure 1

(a) Longitudinal and transverse views of normal skeletal muscle. The arrow heads show innumerable hyperechoic dots/dashes, which represent the perimysium. The epimysium (arrows) demarcates the hyperechoic fascial boundary surrounding the muscle. (b) Longitudinal and transverse views of a normal Achilles tendon. Normal tendon appears as an array of echogenic parallel lines (bundles of collagen fibres) or as multiple echogenic dots on short axis

Figure 2

(a) Longitudinal and transverse views of the left gastrocnemius muscle in a female runner showing a 5.5 cm myofascial separation tear consistent with a grade II injury. Complexity and stranding within the hypoechoic area represents blood clot. Intact muscle fibres are seen on the transverse view. (b) Longitudinal and transverse views of the hamstring muscle in a footballer demonstrating moderately extensive hyperechoic change representing haemorrhage and oedema (white arrow) suggestive of a grade II injury. Contemporaneous MRI images of the same injury show a small discrete haematoma and muscle fibre retraction. (c) A longitudinal view of the hamstrings in a water skier with a corresponding MRI image. The white arrow demonstrates the proximal end of the retracted muscle stump consistent with a grade III injury

Figure 3

(a) Longitudinal and transverse views of the vastus medialis obliquus muscle following blunt direct trauma. Diffuse hyperechoic change and loss of fibrillar architecture represents acute bleeding and oedema within the muscle with no loss of continuity. (b) Longitudinal and transverse views of a 9 cm calf haematoma following direct trauma. This may evolve into a more hypoechoic looking seroma which may be amenable to aspiration to expedite recovery. (c) Transverse view of the anterior thigh in a footballer 3 months post blunt trauma. A highly reflective curvilinear opacity within the muscle substance (white arrow) casting dense posterior acoustic shadowing. The corresponding lateral radiograph shows a smooth lobular calcified mass lying anterior to the femoral cortex, consistent with myositis ossificans. (d) An acute muscle hernia in a professional footballer following blunt trauma. Bulging of the tibialis anterior muscle through a defect in the overlying fascia (*) is shown with adjacent haemorrhage

Figure 4

A coronal fluid sensitive MRI image and a longitudinal ultrasound view, in different patients, showing a pocket of serous fluid lying at the junction of the subcutaneous fat and underlying fascia lata. Often from blunt trauma, the subcutaneous fat sheers off from the underling fascia creating a potential space

Figure 5

(a) A panoramic longitudinal view of the extensor mechanism in a middle aged man showing a complete full thickness rupture of the central fibres of the quadriceps tendon. Intact tendon fibres of vastus lateralis were seen. The partially retracted tendon ends are shown (*). Normal fibrillar structure of the patellar tendon is demonstrated (white arrow). (b) Longitudinal and transverse views of the right tibialis posterior tendon. There is complete loss of continuity (grade III) of the tendon with hypoechoic fluid seen within the tendon sheath. (c) Longitudinal and transverse views of the proximal patellar tendon showing thickening, hypoechoic change, and loss of fibrillar architecture. Focal areas of dystrophic calcification represented by three echogenic foci are also present (white arrow). Appearances are consistent with chronic patellar tendinosis with neovascularity within the proximal patellar tendon

Figure 6

(a) A longitudinal view of a normal left MCL which appears thin with preserved fibrillar architecture. In comparison, a longitudinal view of an injured right MCL which is thickened and hypoechoic but remains intact (grade II injury). The medial joint space and medial meniscus (*) are seen deep to the MCL. (b) The white arrows demonstrate grossly thickening hypoechoic change to the right anterior talofibular ligament following an inversion injury consistent with an acute grade II injury (* = fibular; + = talus)