Is It Lower Back Pain Or SIJ Pain?

Why Some One-Sided Back Pain May Actually Be SIJ Related

Many people experiencing pain around the lower back or buttock wonder whether the symptoms are coming from the spine itself or the sacroiliac joint, often shortened to the SIJ.

At Sydney Physio Clinic in Sydney CBD, this is a common discussion during assessments, particularly in people experiencing one-sided lower back pain, pain turning in bed, or discomfort during walking and standing.

The challenge is that SIJ pain and lower back pain can behave very similarly. In fact, research suggests it can sometimes be difficult to confidently isolate one exact structure as the sole source of symptoms.

However, certain symptom patterns and aggravating movements may help guide assessment and rehabilitation.

What Is The Sacroiliac Joint?

The sacroiliac joints connect the sacrum at the base of the spine to the pelvic bones on either side.

These joints help transfer load between the upper body and legs during activities such as walking, standing, lifting, and turning.

Although the SIJs only move a small amount, they still experience significant forces throughout the day.

Sacroiliac Joint related pain is usually felt around:

• The dimples near the lower back
• One side of the pelvis
• The buttock region
• The back of the hip

Sometimes symptoms may also refer into the groin or upper thigh.

What Does Typical Lower Back Pain Feel Like?

Lower back pain is a broad term that may involve discs, joints, muscles, connective tissues, or nerves around the lumbar spine.

Symptoms often vary depending on the movements and positions involved.

Common lower back pain patterns may include:

• Pain after sitting
• Bending-related pain
• Morning stiffness
• Pain getting out of a chair or car
• Pain during lifting
• Stiffness after inactivity

Some people may also experience pain spreading into the leg if nearby nerves become irritated.

Common Signs That May Suggest Sacroiliac Joint Irritation

SIJ-related symptoms are often more one-sided.

People commonly describe:

• Pain on one side of the back
• Pain around the buttock
• Discomfort turning in bed
• Pain standing on one leg
• Pain climbing stairs
• Discomfort during transitional movements

Many people with SIJ irritation also report discomfort when:

• Rolling in bed
• Getting in or out of the car
• Walking for longer periods
• Standing unevenly
• Taking large steps

Pregnancy and postpartum changes can also temporarily increase sensitivity around the SIJs because of hormonal and load distribution changes.

Why Turning In Bed Is Common With SIJ Pain

Turning in bed often creates rotational force through the pelvis.

If the region is already sensitive, these twisting movements may temporarily aggravate symptoms.

This is one reason some people feel sharp or localised pain when rolling from side to side overnight.

However, disc-related lower back pain can also cause discomfort turning in bed. Because of this overlap, assessment usually looks at the overall symptom pattern rather than one single movement alone.

Research Around SIJ Pain Is Complex

The SIJ is an area that has generated significant discussion within musculoskeletal research.

Research suggests the SIJ can contribute to lower back pain in some people, particularly when pain is localised around the posterior pelvis. However, accurately diagnosing SIJ pain remains challenging because symptoms overlap heavily with lumbar spine and hip conditions.

A review published in the Journal of Orthopaedic & Sports Physical Therapy noted that no single clinical test reliably identifies SIJ pain on its own. Instead, clinicians often use a combination of movement patterns, symptom behaviour, and provocation tests.

This is one reason modern physiotherapy assessments focus heavily on the overall presentation rather than relying on one isolated finding.

Can Scans Diagnose SIJ Pain?

Imaging does not always provide clear answers.

Many people with pain have minimal findings on scans, while others without pain may show age-related changes around the pelvis or lower back.

Because of this, symptoms, movement behaviour, and clinical assessment are often more useful than scans alone.

Why Hip And Glute Strength Matter

The hips and gluteal muscles play an important role in pelvic stability and movement.

If these muscles become weak or deconditioned, the pelvis and lower back may become more sensitive during walking, standing, and turning movements.

This does not mean the pelvis is “out of alignment” or unstable. Instead, reduced movement tolerance and muscle capacity may contribute to increased sensitivity around the region.

Rehabilitation often focuses on:

• Gluteal strengthening
• Hip mobility
• Movement confidence
• Load tolerance
• Gradual return to activity

How Physiotherapy Can Help

Management usually focuses on improving movement tolerance rather than trying to permanently “realign” the pelvis.

At Sydney Physio Clinic, rehabilitation commonly focuses on:

• Reducing sensitivity
• Improving strength and mobility
• Restoring confidence with movement
• Improving walking and standing tolerance
• Returning comfortably to work, exercise, and daily activities
• Prescription of appropriate treatment aids

Most people improve best with gradual loading and movement-based rehabilitation rather than prolonged rest.

When Should SIJ Or Lower Back Pain Be Assessed?

It may be worth seeking assessment if:

• Pain is becoming more frequent
• Symptoms are affecting sleep or work
• Pain spreads into the leg
• Walking or standing tolerance is reducing
• You are avoiding movement because of symptoms
• Symptoms are not improving over time

A physiotherapist can help assess movement patterns, symptom behaviour, mobility, and strength to better understand what may be contributing.

FAQs About SIJ Pain And Lower Back Pain

How do I know if my pain is SIJ or lower back pain?

SIJ pain is often more one-sided and commonly aggravated by turning, standing unevenly, or transitional movements. However, overlap with lumbar spine pain is very common.

Can SIJ pain cause buttock pain?

Yes. SIJ-related symptoms are commonly felt around the buttock and posterior pelvis.

Does pregnancy increase SIJ pain?

Pregnancy and postpartum changes may temporarily increase sensitivity around the pelvis and SIJ region in some people.

Can scans confirm SIJ pain?

Not always. Clinical assessment and symptom behaviour are often more useful than scans alone.

Can physiotherapy help SIJ pain?

Physiotherapy may help improve strength, movement confidence, mobility, and tolerance to walking, standing, and daily activities.

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