Snapping hip syndrome and pelvic injuries: causes and anatomy

Q: What intra-articular pathologies can cause snapping hip syndrome?

The cause of snapping hip syndrome of intra-articular etiology can be an acetabular labral tear. Unlike extra-articular causes, this form of pathology is more often symptomatic and pain is more frequent. The sound during hip joint movements in such cases resembles a "click" more than a snap. Magnetic resonance imaging (MRI) is used to detect intra-articular pathology. However, when interpreting the results, one should consider the risk of discovering incidental intra-articular findings, while the tendon may remain the true cause of the snapping.

Q: Which ligaments of the pelvic ring are ruptured in an "open-book" fracture depending on the degree of diastasis?

In "open book" pelvic fractures (resulting from anteroposterior compression), the extent of ligamentous injury depends on the magnitude of the pubic symphysis diastasis. - Type I — with a small diastasis (up to 2.5 cm), there is a rupture of the anterior portion of the sacroiliac joint, while the posterior ligaments remain intact. - Type III — with a diastasis greater than 2.5 cm, both the anterior and posterior ligaments of the sacroiliac joint rupture, which is accompanied by dislocation.

Q: Contraction of which muscles leads to avulsion fractures of the ischial tuberosity and anterior iliac spines?

Avulsion fractures at tendon attachment sites result from a sudden contraction of biarticular muscles. - Rectus femoris muscle (m. rectus femoris) — its contraction leads to the avulsion of the anterior inferior iliac spine. - Hamstring muscles — their contraction causes an avulsion of the ischial tuberosity apophysis, which can occur during the "splits" or long jumps.

Q: What clinical signs indicate a urethral injury in a pelvic fracture?

Urethral injury in pelvic fractures is indicated by the following signs: - Bleeding — passage of blood from the external urethral meatus. - Hematoma — formation of hemorrhage in the perineal and/or scrotal region. - Voiding dysfunction — absence of spontaneous urination against the background of constant urine leakage. - Deformation of bladder contours — determined in the presence of a concomitant pelvic extraperitoneal hematoma. - Presence of unstable pelvic injuries.

Snapping hip syndrome (Coxa saltans)

The patient feels or hears a mechanical click or snap during hip flexion and extension.

Extra-articular causes: Most commonly painless, but can be complicated by local bursitis.
Lateral snapping: Occurs when the tensor fasciae latae (m. tensor fasciae latae) or the tendon of the gluteus medius rolls over the greater trochanter.
Medial snapping: Associated with friction of the iliopsoas tendon (m. iliopsoas) against the lesser trochanter or pelvic bones.
Intra-articular causes: Accompanied by pain, and the sound resembles a "click". A typical example is a labral tear.

Diagnosis of medial snapping includes a provocative test: passive extension and internal rotation of the hip. Treatment for painless forms is conservative observation; for bursitis, rest and stretching are prescribed, and in refractory cases, surgical release.

Iliotibial band syndrome

This is a classic overuse injury commonly seen in runners. The iliotibial band (tractus iliotibialis) rubs against the lateral epicondyle of the femur during knee flexion and extension.

When the knee is flexed, the band acts as a flexor.
When nearly straightened, it acts as an extensor.

The main complaint is progressive pain in the lateral aspect of the knee during exertion. For diagnosis, a test is performed: passive knee flexion while lying on the unaffected side (with slight hip flexion) elicits pain due to band compression. Treatment consists of load reduction and stretching exercises.

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Anatomy and injuries of the pelvic ring

The pelvic ring connects the axial skeleton to the lower extremities and protects the pelvic organs. It consists of the fused ilium, ischium, and pubis forming the acetabulum, as well as the sacrum.

Fractures are classified by mechanism:

High-energy: Occur in motor vehicle accidents, often accompanied by massive internal hemorrhage and shock. Treatment priority follows the "life before limb" principle (ATLS protocol). Severe injuries can occur without fractures (ruptures of the pubic symphysis ligaments or the sacroiliac joint).
Low-energy: Typical for elderly osteoporotic patients following falls. These are usually stable pubic rami fractures requiring early mobilization.
Avulsion: Encountered in athletes during sudden muscle contraction. An apophysis fragment is torn off (e.g., the ischial tuberosity or iliac spines).

Classification of high-energy fractures

Injury patterns (by direction of force):

Lateral compression: Ipsilateral fractures of the pubic rami and the sacrum or iliac wing.
Anteroposterior compression: Diastasis of the pubic symphysis ("open-book" configuration). The wider the diastasis, the more ligaments (anterior and posterior) are ruptured.
Vertical shear: The most severe type with displacement of one hemipelvis and a high risk of visceral injuries.

On examination, it is important to rule out a urethral injury (blood at the meatus) — in this case, urinary bladder catheterization is contraindicated.

Briefly: answers to topical questions

What intra-articular pathologies can cause snapping hip syndrome?

A labral tear (labral tear) can be the cause of snapping hip syndrome of intra-articular etiology. Unlike extra-articular causes, this form of pathology is more frequently symptomatic, and pain is more common. The sound during hip movements in such cases resembles a "click" rather than a snap. Magnetic resonance imaging (MRI) is used to detect intra-articular pathology. However, when interpreting results, one must consider the risk of incidental intra-articular findings, whereas the tendon may remain the true source of the snapping.

Which ligaments of the pelvic ring are ruptured in an "open-book" fracture depending on the degree of diastasis?

In pelvic ring fractures of the "open-book" type (from anteroposterior compression), the extent of ligamentous injury depends on the magnitude of pubic symphysis diastasis.

Type I — with a small diastasis (up to 2.5 cm), rupture of the anterior portion of the sacroiliac joint occurs, while the posterior ligaments remain intact.
Type III — with a diastasis greater than 2.5 cm, both the anterior and posterior ligaments of the sacroiliac joint rupture, which is accompanied by dislocation.

Contraction of which muscles leads to avulsion fractures of the ischial tuberosity and anterior iliac spines?

Avulsion fractures at tendon attachment sites result from the sudden contraction of biarticular muscles (muscles crossing two joints).

Rectus femoris (m. rectus femoris) — its contraction leads to avulsion of the anterior inferior iliac spine.
Hamstrings (hamstrings) — their contraction causes avulsion of the ischial tuberosity apophysis, which can occur during splits or long jumps.

What clinical signs indicate a urethral injury in a pelvic fracture?

Signs indicating urethral injury in pelvic fractures include:

Bleeding — discharge of blood from the external urinary meatus.
Hematoma — formation of a bruise in the perineal and/or scrotal region.
Urinary dysfunction — absence of spontaneous urination accompanied by continuous urine leakage.
Deformation of bladder contours — determined in the presence of an associated intrapelvic hematoma.
Presence of unstable pelvic injuries.

Class and exam questions

What is coxa saltans?

This is the Latin name for snapping hip syndrome. It translates as "dancing" or "jumping" hip, as the condition frequently occurs in dancers.

How to differentiate iliotibial band syndrome from a meniscus tear?

In iliotibial band syndrome, pain is localized at the contact point of the band with the lateral femoral epicondyle, whereas in a meniscus tear, tenderness is palpated along the lateral joint line (distally).

Why is hypothermia dangerous in severe pelvic trauma?

Patient cooling leads to coagulopathy, which exacerbates bleeding from injured pelvic vessels. Therefore, prevention of hypothermia is critically important.

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What else to study on this topic

Anatomical structure of the acetabulum (columns and walls).
Mechanisms of acetabular fractures from a dashboard injury (flexed knee impact).
Ligamentous apparatus of the pelvis: anterior and posterior complexes.
ATLS protocol principles in severe polytrauma with pelvic injury.
Differential diagnosis of intra- and extra-articular causes of hip snapping.

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