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Ultrasound & snapping hip; how can it help?



Can ultrasound help in the assessment of snapping hip syndrome?


A snapping hip syndrome is a specific condition characterised by a snap or click sensation at the front or side of the hip when performing certain movements. This is usually associated with pain or discomfort in the area. The article discusses the causes of snapping hip syndrome, how the diagnosis is established, and answers the frequently asked questions about the condition.


What is snapping hip syndrome?

The syndrome describes a group of conditions that result in a sharp snap or click sensation (which may be audible) around the hip joint when performing certain movements. The snap can happen during simple daily activities like walking, standing up from a sitting position or crossing your legs. It can also happen when doing sports activities like running.


What are the types of hip snapping?

There are two types of hip snapping:

1. External snapping - This is the most common type and usually happens when a tendon moves abruptly over an area of bony prominence. It is usually harmless but can be annoying. Repeated snapping can irritate the tendon causing local pain and discomfort.

2. Internal snapping. This is less common and refers to a sensation of deep click inside the hip joint. It is usually related to injury to the cartilage or labrum and will be discussed further below.


What are the causes of snapping hip syndrome?


External hip snapping is usually due to tendon problems. Two tendons around the hip joint can particularly predispose to snapping.


If the snapping is felt at the front of the hip, this usually comes from the movement of the iliopsoas tendon as it passes at the front of the hip. The iliopsoas tendon is a major hip flexor muscle (flexion is the movement you do when you bring your knee towards your chest, like in the picture).

The iliopsoas tendon consists of two components (one for the iliacus and the other for the psoas muscles). The two tendons should move smoothly together during hip flexion and extension. However, in some people, the two tendons can flip abruptly over each other when the hip and knee are moved from the flexed position (as shown in the picture above) to the extended position (when the knee and hip are straightened), resulting in a snap. This can be felt at the front of the hip during simple movements like walking and getting out of the car. It can be associated with inflammation or irritation of the iliopsoas tendon/bursa, a condition referred to as iliopsoas tendonitis/bursitis


If the snap is felt at the side of the hip, this is usually due to movement of a large tendinous structure “called the iliotibial (IT) band” as it passes over a bony prominence at the outer and upper aspect of the leg/thigh bone (called the greater trochanter). This is the most common type of hip-snapping we see in our practice. Normally, the IT band lies behind the greater trochanter when the hip is straight (extended) and moves to the front of the bone on hip flexion. However, if the IT band is tight, the movement can be abrupt, and a snap can be felt. This can happen during normal daily activities like walking and going upstairs. Repeated clicking here can irritate the IT band and cause pain at the outer aspect of the hip. This should not be mistaken for greater trochanteric pain syndrome. The presence of clicking history helps differentiate the two conditions. Ultrasound is very useful in confirming the diagnosis and performing a dynamic assessment. This will directly visualise the cause of clicking and assess the gluteal tendons and the IT band for any inflammation.




Internal hip snapping- This usually results from an intra-articular cause (a problem inside the joint). This can be due to an injury or tear to the articular cartilage or the labrum. The hip joint is a ball and socket type joint formed by the articulation between the femoral head (the head of the long thigh bone) and the acetabulum (a cup-shaped bone that is part of the pelvis). It forms the socket that accommodates the ball (the femoral head). The femoral head and the acetabular surfaces are covered by "articular cartilage". This special tissue covers the bone surfaces within our joints to ensure smooth and frictionless movement. The labrum is another essential structure within the hip joint. It is a special type of cartilage that forms a ring along the acetabular margin. This increases the hip joint stability by deepening the socket and simultaneously allows for reasonable joint movement.


Injury to the cartilage or the labrum (labral tear) can predispose to internal hip snapping. There could be a history of previous trauma, particularly during sports like running, football and tennis. Internal snapping is also seen in people who repeatedly perform extreme hip movements (like dancing).


How to diagnose snapping hip syndrome?

Usually, the diagnosis is suspected clinically and confirmed on imaging. You need to be assessed by a specialist to establish the probable site and cause of hip snapping. A hip X-ray would be useful to assess the bones and the hip joint space. A hip ultrasound would be the most useful test, as it can perform a dynamic assessment to directly demonstrate the abrupt movement of the tendons in real time, confirming the type of hip snapping. MRI can also be useful, especially in suspected internal snapping syndrome, to assess the labrum and the articular cartilage.


What is the treatment for snapping hip syndrome?

Treatment usually involves physiotherapy, particularly stretching exercises, to reduce muscle tightness. Strengthening exercises are also helpful in improving hip joint stability. Soft tissue therapy can also be useful in reducing muscle tightness. Other treatment options include patient education and avoidance of movement that can cause the snap, using ice and anti-inflammatory tablets.


Can cortisone injections help in snapping hip syndrome?

Ultrasound-guided injections play a minor role in managing hip snapping and are usually reserved for resistant cases when the condition is associated with pain interfering with the physiotherapy program. The cortisone is injected into the iliopsoas tendon sheath/bursa or between the IT band and the greater trochanteric in external hip snapping. These injections should be performed under ultrasound guidance to ensure a safe, effective and accurate procedure.


Can surgery help with snapping hip syndrome?

Surgical treatment can be an option, especially in internal snapping syndrome secondary to a labral tear. A keyhole surgery (arthroscopy) can be done to repair the tear. Other treatment options include iliopsoas tendon release and Iliotibial band lengthening. A specialist hip surgeon would be the best person to advise you about the surgical treatment options.



Hip conditions and treatments

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