The iliopsoas tendon can be evaluated with ultrasound or magnetic resonance.
The major advantages of ultrasound include dynamic evaluation of structures,
low cost and wide availability while MR imaging provides higher soft tissue resolution and is particularly useful for showing other structures like bones and joints.
US EVALUATION:
To examine this tendons with ultrasound,
one trick is first look for the rectus femoris in the axial plane,
which is very easy to identify due to its characteristic central septum,
and continue it proximally until its proximal insertion in the anteroinferior iliac spine.
Once there we move the probe medially and we will find a plane depicting both muscular bellies of the iliac muscle and an hyperechogenic tendon lying on the pectinate eminence (Fig.4).
If we want to study the distal insertion of the tendon we better ask the patient to flex the knee and externally rotate the hip positioning the ankle over the contralateral knee (6) (Fig.5 and 6).
MRI EVALUATION:
Psoas iliacus tendon-muscle unit is very well evaluated in the axial plane in magnetic resonance.
We show a sequence in which both the muscle and the tendon are followed until their distal insertion (Fig.7).
PATHOLOGY:
Injuries to the iliopsoas tendon unit are relatively uncommon and may manifest as anterior hip or groin pain,
weakness of hip flexion or inability to bear weight.
Iliopsoas tendon pathology include a wide variety of abnormailities such as traumatic,
inflammatory and infectious disease.
Major causes of iliopsoas tendinosis are acute trauma and overuse resulting from repetitive hip flexion.
Activities that may predispose to iliopsoas tendinosis include dancing,
ballet,
cycling,
rowing,
running and gymnastics.
Imaging manifestations of iliopsoas tendinopathy can be categorized as tendinosis,
intramuscular strains,
partial and complete tears and iliopsoas bursitis.
We discuss the different findings of each pathology using US and MR.
- MYOTENDINOUS RUPTURE:
It is a very uncommon pathology and it is better demonstrated on MR.
T2 weighted images will show a feathery pattern of the muscle accompanied with edema along the fascia.
- TENDINOSIS:
The iliopsoas tendinosis is usually a consequence of either a traumatic event or chronic overuse.
MR images depict signal hyperintensity of the tendon or the surrounding soft tissue (Fig.8) without interruption of the fibers
- TENDON TEARS:
Tendon tears may be partial or complete (Fig.10) and often occur at the distal insertion.
If they are complete,
tendon appears retracted and soft tissue hematoma is usually associated.
- ILIOPSOAS BURSITIS:
The iliopsoas bursa is the largest bursa in the body.
It lies between the muscle-tendon of the psoas,
the superior pelvic brim and the hip joint capsule.
It helps to reduce friction of the tendon withe te surrounding structures.
Bursitis may be secondary to iliopsoas trauma or overuse (Fig.9),
or to arthropathy (especially rheumatoid arthritis)(Fig.10).
INTERNAL SNAPPING HIP
Snapping hip syndrome is an audible or palpable snap in a hip during movement which may be accompanied by pain,
locking,
or a sharp stabbing sensation.
It is thought to affect up to 5-10% of the population,
with a higher prevalence in individuals between the ages of 15 and 40.
The nature of this condition is typically an overuse injury,
with a higher occurrence in activities that involve repetitive hip flexion and extension,
such as dance,
soccer,
gymnastics and running.
There are various causes for snapping hip syndrome,
which can be further classified as external,
internal,
or intra-articular in origin.
According to iliopsoas pathology,
internal snapping hip is due to
subluxation of the iliopsoas tendon over the iliopectineal eminence.
Due to its dynamic nature,
this pathology is best evaluated with ultrasound,
asking the patient to perform certain movements so that the click is manifested.
The most accepted mechanism is the entrapment of the tendon with the iliac muscle (Fig.11).
TREATMENT
In general,
iliopsoas tendon pathology is treated conservatively with anti-inflammatory drugs,
ice and rest.
In cases of bursitis, ultrasound-guided corticoid infiltration can be performed.
With respect to snapping hip if it causes discomfort or the sensation is unpleasant the patient improves by reducing physical activities or modifying sports activities,
adjusting the level of exercises to avoid repetitive movements of the hip.
In very rare cases in which conservatory treatment is not sufficient,
surgical treatment may be recommended.
Certain stretching exercises of the hip and in particular of the iliopsoas muscle can help to avoid tendon injuries and contractures.