Ischiofemoral Impingement

Courtesy: Leandro Alves de Oliviera, Brazil

 

Ischiofemoral Impingement: A Practical Approach to Diagnosis and Management

Overview

• Ischiofemoral impingement is an uncommon cause of posterior hip and deep gluteal pain.
• It occurs when the space between the ischial tuberosity and the lesser trochanter of the femur becomes narrowed.
• The quadratus femoris muscle lies within this space and may become compressed during hip movement.
• Repetitive compression can result in:
  • Muscle edema
  • Tendinous or muscular injury
  • Fatty infiltration
  • Atrophy
  • Occasionally, tearing
• The condition is reported more frequently in women.
• Because symptoms overlap with several other causes of deep gluteal pain, diagnosis requires correlation between:
  • Clinical history
  • Physical examination
  • Imaging findings
  • Response to targeted injection when appropriate

Why Ischiofemoral Impingement Is Important

• Deep buttock pain is frequently attributed to:
  • Piriformis syndrome
  • Sciatic nerve disorders
  • Proximal hamstring pathology
  • Lumbar spine disease
  • Sacroiliac joint pathology
• Ischiofemoral impingement should be considered when these diagnoses do not adequately explain the patient’s symptoms.
• Failure to recognize the condition may result in prolonged ineffective treatment or unnecessary procedures.
• It is particularly important to distinguish true ischiofemoral impingement from an incidental reduction in the ischiofemoral space on imaging.

Anatomy and Pathoanatomy

Ischiofemoral Space

• The ischiofemoral space is the interval between:
  • The lateral aspect of the ischial tuberosity
  • The medial aspect of the lesser trochanter
• The quadratus femoris muscle occupies this region.
• Narrowing of this space can result in mechanical compression of the quadratus femoris.

Quadratus Femoris

• The quadratus femoris is a short, quadrilateral external rotator of the hip.
• It extends from the lateral border of the ischial tuberosity to the quadrate tubercle on the intertrochanteric crest of the femur.
• Compression of the muscle can produce characteristic magnetic resonance imaging abnormalities.

Causes and Predisposing Factors

Ischiofemoral impingement can be primary or secondary.

Structural Causes

• Coxa valga
• Abnormal proximal femoral morphology
• Reduced femoral offset
• Femoral version abnormalities
• Abnormal pelvic morphology
• Changes in the relationship between the ischium and proximal femur

Acquired or Iatrogenic Causes

• Previous proximal femoral osteotomy
• Total hip arthroplasty
• Previous hip surgery
• Trauma
• Heterotopic or other abnormal bone formation
• Mass lesions
• Osteochondroma or other space-occupying lesions

Functional Factors

• Hip abductor or adductor imbalance
• Pelvic instability
• Spinal or pelvic movement abnormalities
• Abnormal hip kinematics
• Repetitive activities involving excessive hip extension, adduction or external rotation

The condition is increasingly understood as a multifactorial syndrome, rather than simply a fixed reduction in bony space.

Clinical Presentation

Pain

• The typical symptom is deep buttock or posterior hip pain.
• Pain may be:
  • Insidious in onset
  • Initially mild
  • Progressive over time
  • Chronic in established cases
• Pain may occasionally radiate into the posterior thigh and mimic sciatic pain.
• Some patients report:
  • Snapping
  • Clicking
  • Clunking
  • A catching sensation around the posterior hip

Aggravating Activities

Pain may increase with:

• Long-stride walking
• Running
• Hip extension
• Hip adduction
• External rotation
• Activities requiring repetitive hip movement

Differential Diagnosis of Deep Gluteal Pain

Important alternatives include:

• Lumbar radiculopathy
• Sciatic nerve entrapment
• Piriformis syndrome
• Proximal hamstring tendinopathy or tear
• Sacroiliac joint pathology
• Ischiogluteal bursitis
• Greater trochanteric pain syndrome
• Hip osteoarthritis
• Femoroacetabular impingement
• Acetabular labral pathology
• Stress fracture
• Deep gluteal syndrome
• Myofascial pain
• Tumour or infection in appropriate clinical settings

Clinical diagnosis should therefore not be based on magnetic resonance imaging findings alone.

Physical Examination

Ischiofemoral Impingement Test

• The hip is passively positioned into:
  • Extension
  • Adduction
  • External rotation
• Reproduction of the patient’s characteristic posterior buttock pain supports the diagnosis.

The combination of extension, adduction and external rotation is particularly relevant because it can reduce the available space around the quadratus femoris.

Long-Stride Walking Test

• The patient is asked to walk using a longer-than-usual stride.
• Reproduction of the patient’s familiar buttock pain is considered a positive test.
• This manoeuvre increases hip extension and may reproduce the mechanical conflict.

Additional Examination

A complete examination should also assess:

• Lumbar spine
• Sacroiliac joint
• Hip range of motion
• Hip abductor and rotator strength
• Hamstring function
• Neurological status
• Sciatic nerve-related symptoms
• Gait abnormalities

Imaging

Plain Radiographs

Radiographs may demonstrate:

• Narrowing of the ischiofemoral space
• Proximal femoral morphology
• Coxa valga
• Previous osteotomy
• Arthroplasty-related changes
• Osteochondroma or other bony abnormalities
• Osteoarthritis
• Other causes of posterior hip pain

Appropriate views may include:

• Anteroposterior pelvis
• Lateral hip
• Additional specialised views when required

Magnetic Resonance Imaging

Magnetic resonance imaging is the most useful imaging modality for evaluating suspected ischiofemoral impingement.

Important findings include:

• Reduced ischiofemoral space
• Reduced quadratus femoris space
• Increased signal intensity and edema within the quadratus femoris
• Muscle enlargement or distortion
• Fatty infiltration
• Muscle atrophy
• Muscle or tendon injury
• Associated hamstring or iliopsoas abnormalities
• Associated intra-articular hip pathology

Important Imaging Principle

• Numerical measurements of the ischiofemoral and quadratus femoris spaces can support the diagnosis.
• However, there is no single measurement that should be used in isolation to diagnose symptomatic disease.
• Measurements are affected by hip position and other anatomical variables.
• Imaging findings must therefore be interpreted together with symptoms and examination findings.

Ultrasound

Ultrasound can be useful for:

• Assessing the quadratus femoris
• Dynamic assessment of the region
• Identifying adjacent soft-tissue abnormalities
• Performing image-guided diagnostic injections
• Performing therapeutic injections

It is particularly useful when an image-guided injection is being considered.

Diagnostic Injection

• A targeted injection into the ischiofemoral space can have both:
  • Diagnostic value
  • Therapeutic value
• Temporary substantial improvement in the patient’s characteristic pain following accurately targeted injection supports the diagnosis.
• Ultrasound or computed tomography guidance may be used.

However, response to injection should be interpreted in the context of the complete clinical picture rather than being regarded as an isolated diagnostic test.

Management

Treatment Algorithm

Clinical suspicion

Exclude competing causes of posterior hip and buttock pain

Radiographic and magnetic resonance imaging assessment

Conservative treatment

Reassessment of symptoms and function

Targeted image-guided injection when appropriate

Persistent disabling symptoms despite adequate nonoperative treatment

Consider surgical decompression in carefully selected patients

Conservative Management

Conservative treatment is the first-line approach.

Components

• Patient education
• Activity modification
• Avoidance of provocative hip positions
• Physiotherapy
• Progressive strengthening
• Correction of abnormal movement patterns
• Improvement of hip and pelvic muscle control
• Flexibility and mobility exercises where appropriate
• Analgesic or anti-inflammatory medication when clinically appropriate

The rehabilitation strategy should address the patient’s individual biomechanical and functional contributors rather than focusing exclusively on the measured bony space.

Current literature continues to support conservative management as the initial treatment strategy.

Image-Guided Injection

• Injection may be considered when symptoms persist despite rehabilitation.
• Ultrasound or computed tomography g