What are the possible causes of low back pain radiating around the hips into the groin in a patient with no reported injury?

Low Back Pain Radiating Bilaterally Around Hips Into Groin Without Injury

The most likely causes are lumbar disc degeneration with referred pain, hip-related pathology (femoroacetabular impingement syndrome, acetabular dysplasia, or labral/chondral pathology), or lumbar spinal stenosis, and you must immediately exclude cauda equina syndrome before proceeding with diagnostic workup. 1, 2

Immediate Red Flag Exclusion

Before considering common causes, you must rule out cauda equina syndrome, which presents with bilateral symptoms and represents a surgical emergency 2, 3:

• Ask specifically about urinary retention, fecal incontinence, and saddle anesthesia 2, 3
• Assess for motor deficits at multiple levels and bilateral sciatica 2, 3
• If any of these features are present, obtain urgent MRI of the lumbosacral spine within hours 2

Additional red flags requiring immediate attention include fever/recent infection (spinal infection), history of cancer/unexplained weight loss (malignancy), or significant trauma in older patients (fracture) 3.

Most Common Causes in Order of Likelihood

1. Lumbar Disc Degeneration with Referred Groin Pain

Lumbar disc disease at L4-L5 or L5-S1 can cause isolated groin pain without low back pain, as the lower lumbar discs are innervated by L2 dorsal root ganglion neurons, producing referred pain in the L2 dermatome (groin region). 4

• This is often overlooked because patients lack typical low back pain 4
• The bilateral distribution around hips into groin fits this pattern 4
• Pain may be accompanied by neurogenic claudication if spinal stenosis is present 5, 3

2. Hip-Related Pathology

The three most common hip conditions causing groin pain radiating from the low back/hip region are: femoroacetabular impingement (FAI) syndrome, acetabular dysplasia/hip instability, and labral/chondral/ligamentum teres pathology. 1

• FAI syndrome presents as motion-related hip pain with groin pain as the primary symptom, though pain may also be felt in the back, buttock, or thigh 1
• Acetabular dysplasia causes instability and acetabular rim overload during normal activities 1
• Hip pathology frequently coexists with other causes of groin pain, making diagnosis challenging 1

3. Lumbar Spinal Stenosis

Spinal stenosis affects approximately 3% of primary care patients with back pain and causes neurogenic claudication—leg pain and weakness with walking or standing that is relieved by sitting or spinal flexion. 2, 5

• The bilateral nature of your patient's symptoms fits stenosis more than unilateral radiculopathy 5
• Severe stenosis can compromise bowel function in advanced cases 2

4. Soft Tissue Pathology

Extra-articular soft tissue abnormalities including iliopsoas bursitis, trochanteric bursitis, abductor tendinosis, and athletic pubalgia can cause hip and groin pain. 1

• These are less likely to cause bilateral symptoms radiating from the low back 1
• More commonly present as localized hip pain 1

Diagnostic Approach Algorithm

Step 1: History and Physical Examination

Obtain specific details about pain characteristics, neurological symptoms, and red flags 3:

• Pain pattern: Does pain worsen with walking/standing and improve with sitting (suggests stenosis)? Does it worsen with hip flexion/rotation (suggests hip pathology)? 1, 5
• Neurological screening: Assess for saddle anesthesia, urinary/bowel symptoms, bilateral leg weakness 2, 3
• Hip examination: Perform flexion-adduction-internal rotation test (negative test helps rule out hip-related pain, though clinical utility is limited) 1
• Rectal examination: Assess sphincter tone if any concern for cauda equina 2

Step 2: Initial Imaging Strategy

Start with plain radiographs of the pelvis and lumbar spine 1:

• Obtain AP pelvis and lateral lumbar spine radiographs first in nearly all cases 1
• Radiographs screen for osteoarthritis, dysplasia, FAI morphology, fractures, and tumors 1
• A pelvic view is superior to isolated hip radiographs for evaluating bilateral symptoms 1

Step 3: Advanced Imaging Based on Initial Findings

If radiographs are negative, equivocal, or nondiagnostic:

For suspected hip pathology 1:

• MRI without contrast is the first-line advanced imaging 1
• MRI evaluates labral tears, cartilage damage, bursitis, tendinosis, and soft tissue abnormalities 1
• Ultrasound can evaluate iliopsoas bursitis, trochanteric bursitis, and abductor tendinosis 1

For suspected spinal pathology 1, 2:

• MRI of the lumbosacral spine evaluates disc degeneration, stenosis, and nerve root compression 1, 2
• Consider spine imaging for referred pain even when hip symptoms predominate 1

Step 4: Confirmatory Testing for Discogenic Pain

If lumbar disc degeneration is identified on MRI but hip pathology is not excluded 4:

• Hip joint injection with lidocaine can rule out hip joint as pain source (negative test supports discogenic origin) 4
• Provocative discography can confirm disc as pain generator 4
• Anesthetic discoblock provides pain relief if disc is the source 4

Critical Pitfalls to Avoid

Do not assume groin pain always originates from the hip—lumbar disc disease commonly causes isolated groin pain without back pain, and this diagnosis is frequently missed 4.

Do not delay imaging when red flags are present—immediate MRI is indicated rather than waiting the usual 4-6 weeks recommended for nonspecific back pain 3.

Do not rely solely on clinical examination—hip examination tests have good sensitivity but poor specificity, and a comprehensive approach combining history, examination, and imaging is essential 1.

Do not order MRI for nonspecific low back pain without red flags in the first 4-6 weeks—this does not improve outcomes and wastes resources 3.

Remember that multiple pathologies often coexist—hip-related pain frequently occurs alongside other causes of groin pain, requiring evaluation of both spine and hip 1.