Sacral, SI Joint, or Psoas Pain? Understanding Three Common Sources of Hip and Low-Back Discomfort

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By Dr. Stephen Ford

Pain around the sacrum, sacroiliac joint, and iliopsoas can feel very similar, but these structures are not the same. Sacral pain is usually felt in the central or paramedian low back and buttock, SI joint-related pain is often one-sided below the back of the pelvis, and iliopsoas-related pain is more commonly felt in the front of the hip or groin. Symptoms alone cannot confirm the source, so a useful evaluation combines pain mapping, movement testing, hip and lumbar screening, and, when appropriate, medical imaging.

Key takeaways

  • The sacrum is the triangular bone at the base of the spine; the SI joint connects the sacrum to each side of the pelvis.
  • Sacral stress injuries in runners are distinct from routine SI joint-related pain and may require imaging.
  • SI joint pain is often one-sided below the PSIS and may refer toward the groin, but no single test is definitive.
  • Iliopsoas-related symptoms are usually anterior hip or groin symptoms aggravated by hip flexion, hills, sitting, or hip extension.
  • Lumbar spine, hip joint, sacral, SI joint, and iliopsoas symptoms can overlap or occur together.
  • Conservative care may include graded activity, strength training, movement retraining, and manual therapy as an adjunct when appropriate.
  • Saddle numbness, bladder or bowel changes, progressive weakness, fever, significant trauma, unexplained weight loss, or suspected stress fracture require prompt medical evaluation.

Why sacral, SI joint, and psoas pain are easily confused

The sacrum sits at the bottom of the lumbar spine and forms the back portion of the pelvic ring. The sacroiliac joints are the interfaces between the sacrum and the two pelvic bones. The iliopsoas is a deep hip-flexor muscle group that connects the lumbar spine and pelvis to the upper femur.

These structures work together during walking, running, lifting, squatting, and transitions from sitting to standing. When one area becomes sensitive, nearby tissues may change how they share load. That can create overlapping symptoms in the low back, buttock, groin, or hip.

The lumbar spine and hip joint can also refer pain into the same regions. For additional context, see our guide to sciatica versus SI joint-related pain and our comparison of a groin pull versus hip-related pain.

Sacral pain and sacral stress injuries

The sacrum is a broad, triangular bone that connects the lumbar spine to the pelvis. Pain from the sacral region may be felt centrally or slightly to one side in the low back, deep in the buttock, or near the upper pelvic area.

People with mechanically sensitive sacral-region pain may notice symptoms with:

  • Prolonged sitting
  • Rising from a chair or bed
  • Rolling in bed
  • Transitional movements
  • Bending or lifting
  • Repeated impact or single-leg loading

The label “sacral dysfunction” can describe a clinical pattern, but it does not automatically identify a specific injury or structural problem. A clinician should consider the lumbar spine, SI joint, hip, surrounding muscles, and bone before assigning a cause.

Sacral stress injury is a separate concern

A sacral stress reaction or stress fracture is different from routine mechanical SI joint pain. Sacral stress injuries can occur in runners and other athletes when repetitive impact exceeds the bone’s ability to adapt. They may develop after a rapid increase in mileage, hill work, speed training, or impact volume.

A stress injury may produce:

  • Deep central or slightly off-center sacral pain
  • Pain that increases with running, hopping, or prolonged standing
  • Focal tenderness over the sacrum
  • Symptoms that persist or worsen despite ordinary activity modification
  • Pain at rest or at night in more advanced cases

There is no simple home test that reliably confirms a sacral stress injury. When the history and examination raise concern, a medical evaluation and imaging, often MRI, may be appropriate. Continuing to run through suspected bone stress injury may increase the risk of progression.

Runner performing a controlled bridge with marching knees while a clinician coaches pelvic control

SI joint-related pain

The sacroiliac joint connects the sacrum to the ilium, the large pelvic bone on each side. It helps transfer force between the trunk and legs during walking, running, lifting, and single-leg movements.

SI joint-related pain is often felt:

  • On one side below the posterior superior iliac spine, or PSIS
  • In the buttock or lower pelvic region
  • Along the back of the hip
  • Occasionally in the groin or upper thigh

Symptoms may follow a fall onto the buttock, a twisting event, a lifting incident, pregnancy-related pelvic changes, or a substantial change in walking or training demands. Some people notice more pain with prolonged sitting, stairs, bending, turning in bed, or moving from sitting to standing.

A clinician may use a cluster of provocation tests, including:

  • Thigh thrust
  • Compression
  • Distraction
  • Gaenslen’s test
  • FABER testing

Research suggests that several familiar-pain responses across a provocation cluster may increase confidence that the SI region is contributing. However, no single test is definitive. A positive maneuver can stress more than one structure, including the hip, lumbar spine, and surrounding ligaments.

It is also important to distinguish SI joint-related pain from inflammatory sacroiliitis, fracture, infection, and referred lumbar pain. Those conditions require different evaluation and management.

Iliopsoas-related pain

The iliopsoas is a deep hip-flexor group made up primarily of the psoas major and iliacus. It contributes to hip flexion and helps coordinate movement between the lumbar spine, pelvis, and thigh.

Iliopsoas-related symptoms are more commonly felt in the:

  • Front of the hip
  • Deep groin
  • Lower abdomen or upper thigh
  • Anterior pelvis

Symptoms may increase with:

  • Resisted hip flexion
  • High-knee movements
  • Deep squatting
  • Running uphill
  • Stair climbing
  • Prolonged sitting
  • Stretching the hip into extension
  • Rising from a low chair

Psoas symptoms are often described as a “tight muscle,” but tightness is not a complete diagnosis. Pain may involve the muscle, tendon, bursa, hip joint, lumbar spine, or a combination of structures. A person may also guard the hip because of pain elsewhere, making the iliopsoas feel tense without it being the primary source.

For this reason, treatment should not focus only on aggressively stretching the psoas. The more useful question is how the hip flexor responds to loading, hip extension, trunk position, running mechanics, and progressive strengthening.

Runner performing a controlled standing resisted hip-flexion exercise while a clinician observes hip and pelvic alignment

How a clinician differentiates these pain sources

A thorough evaluation starts with the history. Important questions include:

  • Where did the pain begin?
  • Can you point to the most painful area with one finger?
  • Did symptoms follow a fall, twist, collision, or training increase?
  • Is pain central, one-sided, posterior, anterior, or deep in the groin?
  • Is running or impact more provocative than sitting?
  • Does resisted hip flexion reproduce familiar pain?
  • Are there numbness, tingling, weakness, or changes in reflexes?
  • Do coughing, sneezing, or spinal movements change the symptoms?
  • Is pain present at rest or during the night?

The physical examination may include:

  1. Pain-location mapping: Central sacral pain, inferomedial PSIS pain, and anterior groin pain suggest different starting points for the assessment.
  2. Lumbar screening: Repeated spinal movements, neurologic testing, strength, sensation, reflexes, and nerve-tension testing may help identify lumbar or nerve-root involvement.
  3. Hip screening: Hip range of motion, FABER and other hip maneuvers, gait, squatting, and single-leg control can help assess hip-joint and surrounding-tissue contributions.
  4. SI provocation testing: A cluster of tests may be more informative than one maneuver.
  5. Load testing: Resisted hip flexion, step-downs, bridges, running drills, or controlled transitions may reveal which tasks reproduce familiar symptoms.

Why imaging may not settle the question

Imaging can be important when a fracture, stress injury, infection, inflammatory condition, tumor, or significant nerve compression is suspected. It is not always definitive for routine mechanical low-back or SI joint-related pain.

Structural findings are common in people without symptoms. Degenerative changes, disc findings, and SI joint irregularities may be present without being the primary pain source. The 2023 diagnostic-accuracy review of disc, SI joint, and facet-related low-back pain supports interpreting imaging alongside the history and examination rather than treating an image as a diagnosis by itself.

Conservative care for sacral, SI joint, and iliopsoas symptoms

When serious conditions have been excluded and conservative care is appropriate, the goal is to rebuild movement tolerance and capacity rather than chase a label.

For mechanically sensitive sacral-region pain

A plan may include:

  • Temporarily reducing impact or painful transitions
  • Maintaining tolerable walking and daily movement
  • Gradual trunk, hip, and lower-extremity strengthening
  • Progressive reintroduction of running or jumping when appropriate
  • Monitoring symptoms during the session and the following day

Suspected sacral stress injury should not be managed with a generic exercise program until appropriate medical evaluation has occurred.

For SI joint-related symptoms

A clinician may consider:

  • Modifying painful lifting, twisting, stairs, or single-leg loads
  • Lumbopelvic and hip strengthening
  • Gluteal and trunk endurance work
  • Gait and single-leg movement retraining
  • Gradual exposure to work, running, or sport demands
  • Manual therapy as an adjunct to exercise and movement progression

Manual therapy may help some people tolerate movement, but it should be part of a broader plan rather than the only strategy.

For iliopsoas-related symptoms

Management may include:

  • Temporarily modifying hills, deep squats, high-knee work, or prolonged sitting
  • Adjusting sitting position and taking regular movement breaks
  • Progressive hip-flexor loading rather than repeated aggressive stretching
  • Gluteal, trunk, and hip-extensor strengthening
  • Movement retraining during running, squatting, and transitions
  • Gradual return to hills, speed, and longer training sessions

Our guide to returning to exercise after an injury explains how to rebuild load without automatically starting from zero.

Runner performing a controlled step-down and landing drill while a clinician observes sacral and hip alignment

Red flags that require prompt medical evaluation

Seek urgent or prompt medical care for:

  • Numbness in the saddle region
  • New bladder or bowel changes
  • Difficulty starting or controlling urination
  • Progressive weakness in both legs
  • Rapidly worsening numbness, weakness, or coordination
  • Significant trauma or a fall with an inability to bear weight
  • Fever or feeling acutely unwell
  • Unexplained weight loss
  • A history of cancer with new back or pelvic pain
  • Severe or persistent night pain
  • Pain suggesting a sacral or pelvic stress fracture
  • Pain that is worsening despite reducing activity

These symptoms are not appropriate for a routine exercise progression or manual therapy visit without medical assessment.

Not Sure What’s Causing Your Hip or Low-Back Pain?

Pain around the low back, pelvis, SI joint, hip, and groin can have overlapping symptoms. A clinical evaluation can help determine which structures may be contributing and whether additional medical evaluation or imaging is appropriate.

Dr. Stephen Ford at Dynamic Spine and Performance Center in Katy, Texas evaluates and treats musculoskeletal conditions involving the low back, pelvis, hips, and lower extremities.

Contact DSPC to schedule an evaluation.

Research, clinical experience, and practical interpretation

Research: Studies support using a combination of history, physical examination, and selected diagnostic tests when evaluating SI joint-related pain. Imaging is valuable for assessing serious pathology and stress injury, but common structural findings do not always identify the symptomatic structure.

Clinical experience: Athletes and active adults often use one broad label (“hip pain,” “psoas tightness,” or “SI joint pain”) for symptoms arising from several overlapping regions. Location, load response, neurologic findings, and movement quality usually provide more useful information than the label alone.

Practical opinion: The best plan is the one that protects against serious conditions while progressively restoring the movements and loads that matter to you. That may involve chiropractic care, therapeutic exercise, mobility work, sports rehabilitation, or referral for imaging and medical care when indicated.

At Dynamic Spine & Performance Center, an evaluation may include movement assessment, hip and lumbar screening, strength testing, therapeutic exercise, and individualized return-to-activity planning.

Clinical disclaimer

This article is for general educational purposes and is not a diagnosis or individualized treatment plan. Sacral, SI joint, psoas, hip, and lumbar symptoms can overlap, and some pelvic or sacral conditions require medical evaluation or imaging. Seek urgent care for saddle numbness, bladder or bowel changes, progressive weakness, fever, significant trauma, suspected fracture, or other serious symptoms.

If hip, pelvic, buttock, or low-back pain is limiting your training, sleep, work, or daily movement, contact Dynamic Spine & Performance Center to discuss an individualized evaluation. The goal is to understand how your symptoms respond to movement and load, identify appropriate next steps, and build a progressive plan around your activity goals.

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