What are the potential causes and treatment options for a patient experiencing right hip pain, leg swelling, and groin pain, and what diagnostic tests and interventions may be necessary to determine the underlying condition?

Right Hip Pain with Leg Swelling and Groin Pain: Diagnostic and Management Approach

You must immediately exclude life-threatening conditions—particularly deep vein thrombosis (DVT) causing the leg swelling, septic arthritis, or occult fracture—before pursuing musculoskeletal diagnoses, as these directly impact mortality and morbidity.

Critical Red Flags Requiring Urgent Evaluation

The presence of leg swelling is atypical for isolated hip pathology and demands immediate attention:

• DVT must be ruled out urgently with Doppler ultrasound if there is unilateral leg swelling, as this represents a potentially fatal condition 1
• Septic arthritis requires urgent joint aspiration if fever, systemic symptoms, or acute onset are present, as delayed treatment leads to joint destruction 2
• Occult fracture (including stress fracture) must be excluded, particularly in older adults or those with trauma history 2
• Tumor or advanced osteonecrosis should be suspected if night pain is prominent 3

Initial Diagnostic Workup

First-Line Imaging

Obtain AP pelvis and lateral hip radiographs (frog-leg or Dunn view) immediately as the screening test for all chronic hip pain, regardless of suspected etiology 2, 4, 3. These evaluate for:

• Osteoarthritis and joint space narrowing 2
• FAI morphology (cam/pincer lesions, increased alpha angle) 4
• Acetabular dysplasia 4
• Fractures and tumors 3

Addressing the Leg Swelling

• Doppler ultrasound of the lower extremity is mandatory to exclude DVT before attributing swelling to musculoskeletal causes 1
• If DVT is excluded and swelling persists, consider referred lymphatic or venous insufficiency, though this would be unusual with isolated hip/groin pain 1

Differential Diagnosis Based on Pain Pattern

Intra-Articular Hip Pathology (Groin Pain Predominant)

The combination of groin pain with hip pain strongly suggests intra-articular pathology 2:

• Femoroacetabular impingement (FAI) syndrome with labral tear is the most common cause in young to middle-aged active adults, presenting with groin pain, mechanical symptoms (catching/locking), and positive FADIR test 2, 4
• Acetabular dysplasia/hip instability causes groin pain with overload symptoms 2
• Osteoarthritis in older adults presents with groin/lateral hip aching without dermatomal sensory loss 2, 3
• Labral tears, chondral lesions, or ligamentum teres pathology without distinct bony morphology 2

Extra-Articular Causes

• Greater trochanteric pain syndrome (gluteus medius tendinopathy/bursitis) causes lateral hip pain, not typically groin pain 3, 1
• Iliopsoas tendinopathy/bursitis can cause anterior groin pain and internal snapping 2, 5
• Athletic pubalgia/core muscle injury causes groin pain that mimics hip pathology 5, 6

Referred Pain (Critical to Exclude)

• L3 radiculopathy causes buttock, lateral hip, and anterior-lateral thigh pain with dermatomal sensory loss along the medial lower leg—this distinguishes it from hip pathology 7
• Negative hip-specific tests (FABER, FADIR) effectively exclude intra-articular hip pathology and point toward nerve root pathology 7
• Lumbar spine pathology should be evaluated if pain radiates down the leg or if there are neurologic symptoms 2, 3

Advanced Imaging Algorithm

When Radiographs Are Negative or Non-Diagnostic

MRI without contrast is the next appropriate test after plain radiographs for detecting soft tissue pathology, occult fractures, osteonecrosis, and intra-articular abnormalities 2, 3:

• MRI is highly sensitive and specific for labral tears, cartilage defects, and periarticular soft tissues 2, 4
• Direct MR arthrography (with diluted gadolinium 1:200) provides superior visualization of labral tears when FAI syndrome is suspected clinically 4

When to Use Ultrasound

• Ultrasound is useful for evaluating superficial structures: abductor tendons, iliopsoas tendon, trochanteric bursitis, and can guide diagnostic injections 2
• Real-time ultrasound can evaluate snapping hip (coxa saltans) during movement 4
• Ultrasound has limited sensitivity for labral tears compared to MRI/arthrography 2

Lumbar Spine Imaging

• Lumbar spine MRI without contrast is first-line if L3 radiculopathy is suspected (dermatomal sensory loss, negative hip tests) 7
• If lumbar pain is non-specific without radiculopathy or red flags, no initial spinal imaging is required 4

Diagnostic Confirmation with Injection

Image-guided intra-articular hip injection of anesthetic ± corticosteroid confirms the hip as the pain source if symptoms are completely relieved 2, 4:

• This distinguishes intra-articular from extra-articular or referred pain 2
• Can be performed at the time of arthrography 2
• Iliopsoas bursa injection can differentiate iliopsoas tendinopathy from intra-articular pathology 5

Clinical Examination Pearls

• FADIR test (flexion-adduction-internal rotation) is positive in FAI syndrome but has limited specificity 2, 4
• Negative flexion-adduction-internal rotation test helps rule out hip-related pain, though clinical utility is limited 2
• Negative FABER and FADIR tests effectively exclude intra-articular hip pathology and suggest radiculopathy 7
• Most hip clinical tests have good sensitivity but poor specificity—a comprehensive approach combining history, examination, and imaging is essential 2

Treatment Algorithm

Conservative Management (First 6-12 Weeks)

• Activity modification and physical therapy are recommended initially 7
• NSAIDs for pain control 7
• Monitor for progressive neurologic deficit or red flags 7

When Conservative Management Fails

• Epidural steroid injection (for L3 radiculopathy) under fluoroscopic/CT guidance if conservative management fails after 6-12 weeks 7
• Intra-articular corticosteroid injection for confirmed hip pathology 2

Surgical Referral Indications

• Orthopedic/hip surgery referral if radiographs show FAI morphology, FADIR is positive, and MRI/arthrography confirms labral tear—these have good surgical outcomes 4, 1
• Neurosurgical/spine surgery referral for progressive neurologic deficit or failure of conservative management after 6-12 weeks in radiculopathy 7

Common Pitfalls to Avoid

• Do not assume leg swelling is musculoskeletal—always exclude DVT first 1
• Do not rely solely on clinical examination—hip tests have poor specificity and imaging is essential 2
• Do not miss referred pain from the lumbar spine—check for dermatomal sensory loss and perform negative hip-specific tests 7
• Do not order MRI before plain radiographs—radiographs are essential screening and guide further testing 2, 3
• Do not overlook non-musculoskeletal causes of groin pain (hernias, genitourinary, gynecologic, gastrointestinal) 5, 6