IFI Syndrome: A Pain in the Rear


Hip pain can be both distracting and debilitating, nagging at you with each step or movement. While hip pain is sometimes indicative of a structural problem within the joint (intra-articular), pain can often stem from other sources outside of the joint (extra-articular).

Some common causes of extra-articular hip joint pain include:

● Tendon injuries
● Muscle injuries
● Nerve entrapment
● Pelvic floor issues
● Hernias
● Urinary tract conditions

IFI Syndrome

One not-to layman’s terms, it is the location in your pelvic area where the femur, or thigh bone, meets up with the acetabulum surface of your pelvis, which forms the socket of your hip, a ball-and-socket joint.

Psoas subspine ischiofemoral impingement (IFI) is a syndrome that causes ongoing hip pain. It occurs when soft tissue, most notably the quadratus femoris muscle (a strong external rotator located at the posterior of the hip), becomes entrapped between the lesser tuberosity and the ischial tuberosity of your pelvis – or in layman’s terms, the sit bones.

The result is chronic pain in the posterior hip and the groin…literally a pain in the rear!

Causes of IFI

Most commonly seen in women, IFI manifests most severely when the hip is extended, rotated outward (externally rotated), or drawn inward (adducted). It may have something to do with a woman’s wider pelvis, and the angle at which the femur descends from the hip socket. Other likely causes of IFI syndrome are:

● Physical inactivity
● Excessive sitting, creating tight hip flexors and lax hip extensors
● Weak core and pelvic floor muscles
● Excess body weight
● Sedentary lifestyle

Treatment for IFI

While surgical interventions are available for IFI, physical therapy is a more effective, enduring and less invasive solution. Therapy should focus on:

● Increased overall physical activity including walking and stair climbing
● Strengthening of the hip extensor muscles
● Strengthening of the hip abductor muscles
● Strengthening of the internal rotator muscles of the hip
● Strengthening of the quadratus femoris
● Strengthening of the core and pelvic floor muscles
● Stretching of the hip external rotators
● Stretching of the hip flexor muscles

The physical therapy team at NYDNRehab in NYC is trained and equipped to full functionality in a matter of weeks?


In this instance, an athlete was originally diagnosed with minor quadriceps muscle strain and was treated for four weeks, with unsatisfactory results. When he came to our clinic, the muscle was not healing, and the patients’ muscle tissue had already begun to atrophy.

Upon examination using MSUS, we discovered that he had a full muscle thickness tear that had been overlooked by his previous provider. To mitigate damage and promote healing, surgery should have been performed immediately after the injury occurred. Because of misdiagnosis and inappropriate treatment, the patient now has permanent damage that cannot be corrected.

The most important advantage of Ultrasound over MRI imaging is its ability to zero in on the symptomatic region and obtain imaging, with active participation and feedback from the patient. Using dynamic MSUS, we can see what happens when patients contract their muscles, something that cannot be done with MRI. From a diagnostic perspective, this interaction is invaluable.

Dynamic ultrasonography examination demonstrating
the full thickness tear and already occurring muscle atrophy
due to misdiagnosis and not referring the patient
to proper diagnostic workup

Demonstration of how very small muscle defect is made and revealed
to be a complete tear with muscle contraction
under diagnostic sonography (not possible with MRI)


Complete tear of rectus femoris
with large hematoma (blood)


Separation of muscle ends due to tear elicited
on dynamic sonography examination

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