Ischiofemoral Endoscopic Decompression

While rare, in recalcitrant cases when nonsurgical treatment has failed for an extended period of time, surgical treatment may be considered in the form of ischiofemoral decompression, typically with lesser trochanter osteoplasty. This comprises partial resection of the lesser trochanter while preserving the majority of the iliopsoas tendon attachment to widen the ischiofemoral space. This is often performed endoscopically via 2 or 3 small portal incisions. Despite its minimally invasive nature and elective, outpatient surgery designation, the surgery requires access of the posterior thigh adjacent to major nerves and vessels and therefore requires careful consideration of risks and benefits.

Postoperative rehabilitation typically follows for 6-8 weeks after surgery, and patients often return to all sport activities by 8-12 weeks with no restrictions.

Ischiofemoral Impingement Frequently Asked Questions

What is Ischiofemoral Impingement (IFI)?

Ischiofemoral impingement is a relatively uncommon cause of hip pain resulting from compression on the quadratus femoris muscle between the ischium and femoral lesser trochanter. This contrasts femoroacetabular impingement (FAI), a far more common form of hip impingement, which results from compression or abutment between with femoral neck and acetabular rim. These two forms of impingement represent completely separate and distinct entities.

What types of patients commonly present with IFI?

IFI can affect people of all shapes, sizes, age, and activity levels, although it may be experienced more commonly in athletes performing significant hip hyperextension, such as gymnasts and dancers.

After obtaining an MRI for hip pain, the radiologist diagnosed me with IFI. Is this true?

In a word, maybe. Ischiofemoral impingement is primarily a clinical diagnosis, although there are some findings on imaging, whether xray, CT, or MRI, that can be suggestive of reduced ischiofemoral space and may correlate with the clinical condition of ischiofemoral impingement. However, imaging alone is insufficient to make the diagnosis.

How is IFI diagnosed?

IFI is diagnosed with a combination of clinical history, examination, and imaging findings.

Clinical history often includes posterior, deep gluteal pain associated with hip hyperextension, including in the extension phase of walking or running gait, or when gymnasts and dancers perform splits. This is typically not associated with back pain, pain running down the leg, tingling or numbness, or anterior groin hip pain. The presence of these aforementioned symptoms suggests the probability of other conditions.

Physical Examination includes two classic findings: the long-stride walking (LSW) test, and the ischiofemoral impingement (IFI) test:

The LSW test is expected to provoke impingement between the lesser trochanter and ischium in terminal hip extension when the patient walks. The findings of this test are considered positive if the posterior pain is reproducible lateral to the ischium during extension with long strides whereas pain is alleviated when walking with short strides.

The IFI test is performed with the patient in a lateral position. The examiner passively takes the patient’s hip into extension. The IFI test is intended to provoke impingement in extension with a neutral or adducted hip (re-creating the posterior pain lateral to the ischium) and relieves the impingement pain in extension with an abducted hip

The final component of diagnosis is imaging, which serves to support a clinical diagnosis made with history and examination findings, but can not be used in isolation to make the diagnosis.

Using xrays performed in the office, the ischiofemoral space (IFS) is measured, which is the most narrow distance between the cortex of the lesser trochanter and the cortex of the ischial tuberosity. This space should normally be greater than 1.8 cm, and less than 1.8cm may be consistent with IFI.

Advanced imaging, specifically magnetic resonance imaging (MRI), typically reveals isolated edema-like signal in the quadratus femoris muscle. The edema is thought to be due to QFM compression occurring as the muscle passes between the lesser trochanter of the femur and the origin of the ischial tuberosity/hamstring tendons.

How is IFI treated?

The vast majority, over 90% of cases, are successfully treated with nonsurgical treatment including physical therapy, anti-inflammatory medication, and activity modification. Occasionally imaging-guided injections are performed, often to achieve both diagnostic and therapeutic purposes. Because IFI is a dynamic phenomenon typically occurring through a limited arc of motion, physical therapy may often alter hip and pelvis mechanics to avoid impingement or compression to occur during normal movements.

When is surgery required? What does surgery involve?

Postoperative rehabilitation typically follows for 6-8 weeks after surgery, and patients often return to all sport activities by 8-12 weeks with no restrictions.