Ultrasound is a useful imaging modality for evaluation of the hip, knee and ankle.Allowing high-resolution imaging of anatomy while simultaneously allowing dynamic evaluation of the joint, tendons, and ligaments
Intra-articulate effusions in the anterior capsule of the hip joint can be detected as a triangular structure and observed as a dark area of fluid collection that distend the capsule.
Iliopsoas tendinopathy causes a dark, swollen tendon with poor fibre architecture, the iliopsoas bursa communicates with the hip joint, iliopsoas bursitis is sometimes associated with hip joint pathology. An abnormal iliopsoas tendon motion is the common cause of extra-articular snapping hip.
Proximal quadricep tendon tears occur less frequently than in the midsubstance of the muscle belly or at the myotendinous junction.
In the medial hip, Adductor tendinopathy most commonly affects the adductor longus and the gracilis muscles, the tendon can appear dark and thickened.
Greater trochanteric pain syndrome or lateral hip pain is caused by hip abductor tendinopathy or tears, especially in the gluteus medius tendon. Trochanteric bursitis effects one of several superficial bursa of the lateral hip.
Hamstring tendinopathy of the proximal attachment appears dark and swollen. Calcification can occasionally be detected at the tendon insertion or within the tendon.
Ischiogluteal bursitis is also known as “weaver's bottom”, which is caused by prolonged sitting. A fluid accumulation in the ischiogluteal bursa is demonstrated on the bright bony cortex of the ischial tuberosity
Patellar tendinopathy (Jumper's knee) is caused by overuse of the knee extensor mechanism during activities such as jumping or running. This is diagnosed on ultrasound with thickening and decreased brightness of the tendon.
Osgood–Schlatter disease is chronic tendinopathy of the distal patellar tendon. The distal patellar tendon is thickened and dark and may contain fragments from the tibial attachment.
Quadriceps tendon tears tend to be located at the tendon junction or at the tendon's insertion into the patella. In partial tears there is a dark defect representing hematoma. The specificity and sensitivity of ultrasound in the diagnosis of quadriceps tendon tears have been shown to be 100%.
Pre- and infra-patellar bursitis is commonly caused by occupational kneeling and inflammation of the superficial bursa, a condition described as housemaid's or clergyman's knee.
Medial collateral ligament (MCL) injury appears as a thickened structure affecting the deep fibers. The sensitivity of sonography in the detection of MCL injuries is approximately 94%.
Meniscal lesions/tear may appear as a dark cleft coursing within the meniscus. A degenerated meniscus appears swollen. The edges of the meniscus bulge outward and can change the brightness and contours.
Pes anserine bursitis is a commonly observed condition. Ultrasound demonstrates a cystic mass adjacent and deep to the pes anserine tendon. The bursa lies between the insertion of the collateral ligament and the conjoined tendon.
Lateral collateral ligament (LCL)injury presents as focal tenderness, thickened segments, adjacent to the fibular attachment.
Baker's cysts (popliteal cysts) are characteristically crescent shaped, and involve the medial border of the gastrocnemius (calf) muscle and the semimembranosus (hamstring) tendon. it is frequently associated with meniscal tears, or with degenerative and inflammatory arthropathy.
Gastrocnemius muscle injury (tennis leg) is characterized by disruption of the normal, parallel fibres of the tendon at its insertion. Fluid collection is seen within the gastrocnemius muscle.
Achilles Tendon rupture observed 2 and 6 cm from the insertion into the calcaneus (heel bone ), this is called the critical zone with a relative poor blood flow. Rupture of the Achilles tendon is seen as a focal defect between the broken ends of the tendon.
Achilles tendinopathy causes swelling of the tendon and it appears less bright.
Tendinosis is related to degenerative changes within the tendon as it appears swollen and darker due to increased fluid in the tendon.
Tenosynovitis refers to inflammation surrounding the tendon sheath and this can be visualised on ultrasound by assessing the blow flow to the tendon.
Retrocalcaneal Bursitis can become inflamed and appears as a dark triangular structure with increased blood flow.
The retrocalcaneal Bursa is interposed between the Achilles tendon and the posterior calcaneus (heel bone).
Lateral ligament injuries occur secondary to inversion sprains. The three ligaments involved in lateral ligament injuries are the anterior talar fibular ligament (ATFL), calcaneal fibular ligament (CFL), anterior tibiofibular ligament (TFL) and the posterior talar fibular ligament (PTFL).
Peroneal tenosynovitis demonstrates fluid within the tendon sheath and inflammation around the tendon. Peroneal tendon rupture cause an inability to move the foot outwards.
Tibialis Posterior Tendon Dysfunction can occur as a consequence of an acquired flat foot (pes planus), where the tendon becomes inflamed or prone to tears or split tears.