Sacroiliac Joint (SIJ) Pain: Why Does One Side of My Lower Back or Buttock Hurt?

Do you experience a sharp pain on one side of your lower back, just above your buttock?

Perhaps walking upstairs causes a stabbing sensation, rolling over in bed is uncomfortable, or standing on one leg to put your pants on aggravates the pain. Maybe you notice an ache around your pelvis after sitting for a long time, or getting out of the car causes a sudden catch in your lower back. You might even find yourself pointing to one very specific spot near the back of your pelvis when someone asks where it hurts. Pain around the sacroiliac joint can be frustrating because it affects movements we do constantly throughout the day. But pain in this area doesn't automatically mean your pelvis is out of alignment or that something is seriously damaged. Many causes of pain around the SI joint can improve with appropriate assessment, treatment and activity management.

Sharp pain on one side of your lower back or buttock?

Sarah provides individualised osteopathic assessment and care for musculoskeletal lower back and pelvic pain in Milford, Auckland, helping patients understand their symptoms and move more comfortably.

Book an Appointment

Where Is Your Sacroiliac Joint?

Your sacroiliac joints, commonly called the SI joints or SIJs, are located at the back of your pelvis. They connect your sacrum — the triangular bone at the bottom of your spine — to the two large pelvic bones. You have one SI joint on each side. These joints help transfer forces between your spine, pelvis and legs during activities such as walking, standing, climbing stairs and lifting. Unlike your hip or shoulder joints, the SI joints normally move only a small amount. Their main role is to provide stability while allowing limited movement. If you place your hands on the two small dimples at the back of your pelvis, your SI joints sit nearby. Pain in this region can come from the SI joint itself, but it can also be referred from your lower back, hips or surrounding tissues. This is why a proper assessment matters.

What Does SI Joint Pain Feel Like?

Patients often describe SIJ-region pain in different ways. Some experience a constant dull ache, while others notice sharp pain with particular movements.

You might recognise one of these descriptions.

"I get a sharp pain just above my buttock." Perhaps the pain is concentrated around one side of your lower back, close to your pelvis.

"It hurts when I stand on one leg." You may notice discomfort when putting on pants, stepping into the shower or balancing on one leg.

"I get a stabbing pain when I walk upstairs." Climbing stairs or stepping up onto a kerb may aggravate the area.

"Rolling over in bed is painful." Perhaps turning from one side to the other causes a sudden sharp sensation around your lower back or pelvis.

"My lower back hurts when I get out of the car." The combination of twisting, moving your legs and standing up can be uncomfortable.

"The pain travels into my buttock." Some people experience aching around the buttock, hip or upper thigh.

"I feel stiff after sitting for a long time." Perhaps standing up after a long meeting or car journey causes discomfort.

These symptoms can occur with sacroiliac joint-related pain, but they aren't specific enough to confirm the SI joint is the cause. Other conditions, including lumbar disc problems, hip conditions and nerve-related pain, can produce similar symptoms.

What Causes Sacroiliac Joint Pain?

There isn't always one obvious cause. Pain around the SI joint can develop following an injury, changes in activity or irritation of nearby structures.

1. SI Joint-Related Musculoskeletal Pain

The SI joints and their surrounding ligaments can become a source of pain. Symptoms may develop following a fall, sudden movement or increased physical demands. However, it can be difficult to identify the SI joint as the exact source of pain based on symptoms alone.

2. Falls and Injuries

A fall onto your buttock or pelvis may irritate the tissues around the SI joint. You might notice pain when walking, sitting or moving between positions. Significant trauma requires medical assessment to exclude fractures or other injuries.

3. Increased Physical Activity

A sudden increase in running, hiking, gym training or other exercise can sometimes contribute to discomfort around the lower back and pelvis. This doesn't necessarily mean your SI joint is damaged. It may indicate that the tissues around your pelvis are currently struggling with the demands placed on them.

4. Repetitive or Physically Demanding Work

Jobs involving repeated lifting, carrying, bending or prolonged standing can sometimes aggravate pain around the lower back and pelvis. You may notice discomfort after a physically demanding day.

5. Inflammatory Sacroiliitis

Sacroiliitis means inflammation involving the sacroiliac joint. It can sometimes be associated with inflammatory conditions such as axial spondyloarthritis.

Symptoms may include:

• Persistent lower back or buttock pain

• Significant morning stiffness

• Pain that improves with movement rather than rest

• Waking during the second half of the night with back pain

• Alternating pain between the buttocks

Inflammatory sacroiliitis requires medical assessment and may need specialist management.

6. Pain Referred From Your Lower Back or Hip

Sometimes pain felt near your SI joint actually comes from another structure. Lumbar joints, discs, nerve roots and hip conditions can all cause pain around the lower back or buttock. Pain near your SI joint doesn't automatically mean the joint itself is responsible.

Is It SI Joint Pain, Sciatica or a Lumbar Disc Injury?

This is a common question, because these conditions can overlap.

SI Joint-Related Pain

Pain is often felt around one side of the lower back or buttock. It may be aggravated by walking, stairs, rolling over in bed or moving between sitting and standing.

Sciatica

Sciatica usually involves irritation of a nerve root in the lower back. You may notice shooting, burning or electric-shock-like pain travelling down your leg. Tingling, numbness or weakness may also occur.

Lumbar Disc Problems

A symptomatic lumbar disc herniation may cause lower back pain or irritate a nearby nerve root. Some people notice pain when sitting, bending, lifting, coughing or sneezing. If a nerve root is affected, pain may travel down the leg.

Hip-Related Pain

Hip conditions may cause discomfort around the groin, side of the hip or buttock. You might notice pain when walking, putting on shoes, getting into the car or lying on your side. The location of your pain and the movements that aggravate it provide clues, but they don't always identify the exact cause. An assessment helps determine which structures are most likely involved and whether further investigation is needed.

Why Does SI Joint Pain Hurt During Everyday Activities?

Often, it's the small movements you normally do without thinking that become frustrating.

SI Joint Pain When Walking

Does one side of your lower back or buttock hurt when walking? Perhaps you notice pain when taking longer steps, walking uphill or increasing your walking distance. Walking transfers forces through your pelvis with every step. If the structures around your SI joint are sensitive, this may aggravate symptoms.

SI Joint Pain When Climbing Stairs

Climbing stairs requires you to transfer weight from one leg to the other. You might experience a sharp pain around your buttock or lower back when stepping up. Perhaps you find yourself holding the handrail or avoiding stairs when possible.

SI Joint Pain When Rolling Over in Bed

Does turning over in bed cause a sudden stabbing pain around your pelvis? Rolling requires your trunk and legs to move together. If the area is sensitive, this movement may be uncomfortable.

SI Joint Pain When Standing on One Leg

Putting on pants, shoes or socks requires balance and single-leg support. You may notice pain when lifting one leg or transferring your weight.

SI Joint Pain When Getting Out of the Car

Getting out of the car involves rotating your body, moving your legs and standing up. Perhaps you experience a sharp catch around your lower back or buttock during this movement.

SI Joint Pain When Sitting

Some people notice discomfort after sitting for long periods, particularly on firm surfaces. You might find yourself shifting position or needing to stand up regularly.

SI Joint Pain When Running or Exercising

Running, lunges, squats and certain gym exercises place demands on your pelvis and surrounding muscles. You may notice discomfort during activity or afterwards.

SI Joint Pain When Lifting

Lifting groceries, moving furniture, gardening or carrying children can aggravate sensitive structures around your lower back and pelvis. If pain around your SI joint is affecting your walking, stairs, sleep, exercise or everyday activities, an assessment can help identify what's contributing to your symptoms.

Book an SI Joint Pain Appointment with Sarah

What Can I Do to Relieve SI Joint Pain?

The best approach depends on the cause of your symptoms, but several strategies may help manage musculoskeletal pain around the SI joint.

1. Keep Moving Within Comfortable Limits

Gentle walking and regular movement can help maintain mobility and reduce unnecessary stiffness. You don't necessarily need to stop all activity.

2. Modify Activities That Aggravate Your Symptoms

If running, heavy lifting or certain gym exercises increase your pain, consider temporarily reducing the intensity or changing the activity. The aim is to maintain appropriate movement while allowing symptoms to settle.

3. Try Comfortable Sleeping Positions

Some people find sleeping on their side with a pillow between their knees helpful. Others prefer lying on their back with a pillow underneath their knees. Choose a position that reduces your discomfort.

4. Change Sitting Positions Regularly

If prolonged sitting aggravates your symptoms, try standing up and moving around regularly. You don't need to maintain one perfect posture all day.

5. Gradually Strengthen Your Hips and Trunk

Strengthening exercises may help improve your ability to tolerate everyday activities. Depending on your symptoms, this may include exercises for your gluteal muscles, hips and trunk.

6. Try Heat or Cold for Temporary Relief

A warm shower or heat pack may help ease associated muscle discomfort. Some people prefer a cold pack following a recent injury.

7. Avoid Forcing Painful Stretches

Aggressive stretching isn't always helpful, particularly when the exact cause of your pain is unclear. If a movement causes sharp pain or symptoms travelling down your leg, stop and seek guidance.

8. Seek Assessment if Your Pain Persists

If your pain isn't improving, keeps returning or is affecting your everyday activities, an assessment can help determine whether the SI joint, lower back, hip or another structure may be involved. You don't have to wait until walking or getting out of bed becomes extremely painful before asking for help.

Book an Osteopathy Appointment with Sarah

Is My SI Joint Out of Alignment?

You may have heard someone describe SI joint pain as a pelvis being "out of alignment" or a joint being "out of place". However, the SI joints are naturally very stable and only move a small amount. There isn't strong evidence that most SI joint pain is caused by a pelvis being physically out of alignment. Pain may be related to sensitivity in the joint or surrounding tissues, changes in load tolerance or other musculoskeletal factors. The goal of treatment isn't to force your pelvis back into position. Instead, it's to identify what may be contributing to your symptoms and help you move more comfortably.

How Can Osteopathic Treatment Help SI Joint Pain?

If pain around your sacroiliac joint is affecting your everyday activities, osteopathic assessment and treatment may help manage associated musculoskeletal discomfort and improve movement. I'm Sarah Boughtwood, a structural osteopath based in Milford on Auckland's North Shore, with over 10 years of clinical experience. I treat adults and children aged five years and older, helping patients manage musculoskeletal aches, pains and injuries. My approach is to understand not just where your pain is, but how it's affecting your everyday life. Perhaps you're struggling to walk upstairs, roll over in bed, stand on one leg, exercise or get out of the car comfortably.

During your appointment, I'll take the time to understand how your symptoms developed, what movements aggravate them and whether there are signs that the pain may be coming from your lower back, hip or another structure. I'll assess your lower back, pelvis, hips and relevant movement patterns. Where appropriate, I may use a combination of clinical tests to help determine whether the SI joint is a likely source of pain.

Depending on your symptoms and diagnosis, treatment may include:

• Gentle soft tissue techniques to help manage associated muscle discomfort

• Appropriate joint mobilisation where suitable

• Individualised mobility and strengthening exercises

• Advice on modifying activities that aggravate your symptoms

• Practical strategies for walking, stairs, sleeping and lifting

• Guidance on gradually returning to exercise

• Referral for imaging or further medical assessment when indicated

Treatment is tailored to your symptoms, medical history and comfort levels. Hands-on treatment may help manage short-term discomfort for some patients, but it doesn't physically realign the pelvis or guarantee that SI joint pain will resolve. My aim is to help you understand your symptoms, improve your movement and return to everyday activities with greater confidence.

Book an SI Joint Pain Assessment with Sarah

When Should I Be Concerned About SI Joint Pain?

Many causes of pain around the SI joint are musculoskeletal, but some symptoms require medical assessment.

Seek urgent medical attention if you experience:

• Severe pain following significant trauma

• New or progressive weakness in your legs

• Numbness around your groin or saddle area

• New difficulty controlling your bladder or bowel

• Fever or feeling significantly unwell with back or pelvic pain

• Severe unexplained pain that is worsening

New bladder or bowel dysfunction, saddle numbness or rapidly progressive neurological symptoms require emergency medical assessment. Persistent morning stiffness, night pain that improves with movement or symptoms suggesting inflammatory arthritis should also be discussed with your GP. Children with persistent lower back or pelvic pain, a limp or unexplained symptoms should be medically assessed.

Do I Need an X-ray or MRI for SI Joint Pain?

Not everyone with suspected SI joint pain needs imaging. For many musculoskeletal conditions, your medical history and physical examination can help guide initial management. However, imaging may be appropriate following significant trauma, if inflammatory sacroiliitis is suspected or if symptoms suggest another condition requiring investigation. As an osteopath, I can assess whether referral for imaging or further medical evaluation may be appropriate.

Can I See an Osteopath for SI Joint Pain Under ACC?

Sometimes. If your pain is associated with an injury that qualifies for ACC cover, you may be eligible for subsidised osteopathic treatment. For example, symptoms following a fall or a specific lifting injury may qualify, depending on the circumstances and ACC's assessment. Not all SI joint pain is covered by ACC, particularly when symptoms develop gradually without a qualifying injury.I'm an ACC-registered osteopath, and you don't need a GP referral to book an appointment.

Don't Let Pain Around Your SI Joint Make Everyday Movement Difficult

Pain around the sacroiliac joint can affect so many everyday activities. Perhaps you're struggling to walk upstairs, roll over in bed, stand on one leg or get out of the car comfortably. It can be frustrating when simple movements suddenly cause a sharp pain around your lower back or buttock. But pain around your SI joint doesn't automatically mean your pelvis is unstable, out of alignment or permanently damaged. With an appropriate assessment and management plan, many common musculoskeletal causes of pain in this region can improve. If you're experiencing persistent one-sided lower back pain, buttock discomfort or pain around your pelvis, I'd love to help you explore your treatment options.

I'm Sarah, a structural osteopath based in Milford, Auckland, providing individualised care for adults and children aged five years and older.

Let's work towards helping you move more comfortably and get back to the activities you enjoy.

Book an Osteopathy Appointment with Sarah

Sarah Boughtwood | BAppSc(HB), Master of Osteopathy | ACC Registered Osteopath | Milford, North Shore, Auckland

This article provides general information and doesn't replace individual medical assessment.