SI joint pain is increasingly recognized as a significant source of lower back pain in adults over 30, with medical professionals noting a “tremendous growth in the appreciation and treatment of sacroiliac joint complex pain” over the past two decades. Between 15 and 30 percent of adults suffering from chronic, nonradicular pain have SI joint involvement, and approximately 25 percent of patients with chronic low back pain have SIJ dysfunction—meaning an estimated 10 million adults in the US could be affected.
What’s driving this surge in cases among middle-aged and older adults? A combination of eight primary causes that have become more prevalent due to aging, lifestyle changes, modern occupational demands, and previous medical interventions. This article examines the eight causes that doctors say are increasing in adults over 30: age-related degenerative changes, previous spine surgery, leg length discrepancy, occupational and athletic overuse, pregnancy-related joint stress, inflammatory arthritis, osteoarthritis, and trauma. Understanding these causes can help you recognize whether SI joint pain might be behind your lower back discomfort and guide conversations with your healthcare provider about diagnosis and treatment options.
Table of Contents
- Age-Related Degenerative Changes and Declining Joint Mobility
- Previous Spine Surgery and the Adjacent Segment Problem
- Leg Length Discrepancy and Biomechanical Misalignment
- Occupational and Athletic Overuse in Modern Work and Sport
- Pregnancy, Hormonal Changes, and Inflammatory Arthritis
- Trauma and the Long-Term Consequences of Pelvic Injuries
- The Growing Recognition of SI Joint Pain Among Healthcare Providers
- Conclusion
Age-Related Degenerative Changes and Declining Joint Mobility
The sacroiliac joint experiences predictable changes over time that begin as early as puberty and accelerate through adulthood. Cartilaginous changes in the joint reduce its mobility and flexibility with each passing decade, making adults over 30 increasingly vulnerable to SI joint dysfunction. By middle age, many people find their joints simply don’t move as freely as they once did, and this reduced mobility can trigger pain when the remaining movement concentrates stress on the joint’s structures. Osteoarthritis is a frequent contributor to SI joint pain in aging adults, with the joint’s smooth cartilage gradually thinning and underlying bone developing characteristic wear-and-tear changes.
A 45-year-old office worker, for example, might notice that their lower back pain worsens after long car drives or when standing for extended periods—symptoms that reflect the joint’s reduced tolerance for movement rather than any acute injury. The SI joint, once capable of absorbing and distributing force across the pelvis, becomes less forgiving with age. However, it’s important to recognize that not all lower back pain in older adults comes from SI joint dysfunction. Some people experience degenerative changes without pain, while others experience pain from multiple sources simultaneously. Distinguishing SI joint pain from other age-related spinal problems requires clinical examination and sometimes imaging studies.
Previous Spine Surgery and the Adjacent Segment Problem
One of the most underappreciated risk factors for SI joint pain is previous lumbar spine surgery, particularly fusion procedures that permanently alter the mechanics of the lower spine. When a surgeon fuses one or more vertebrae in the lumbar spine to eliminate motion and pain, the stress and movement that would normally occur across those fused segments shifts downward to the SI joint—a phenomenon called adjacent segment syndrome. The SI joint, now bearing additional load it wasn’t designed to handle alone, gradually becomes painful and dysfunctional. This cause is particularly relevant to adults over 30 because many people in this age group underwent lumbar fusion surgery 10, 15, or even 20 years earlier.
A patient who had a successful fusion at age 40 might not develop SI joint pain until age 55 or 60, creating a delayed consequence that they and their doctor might not initially connect. The increased prevalence of SI joint pain diagnoses in recent years partly reflects the aging population of people who had fusion surgery decades ago. Understanding this connection is crucial for anyone considering lumbar fusion surgery, as it highlights the importance of discussing long-term consequences with your surgeon. Non-surgical alternatives should be exhausted first when possible, since SI joint pain that develops as a result of fusion can be difficult to treat and may require its own interventions years down the line.
Leg Length Discrepancy and Biomechanical Misalignment
Leg length discrepancy—a difference in the length of your two legs—is a well-established cause of SI joint pain that many people don’t realize they have. This difference can be true, meaning one leg bone is actually longer than the other, or apparent, meaning the legs are equal in length but pelvic misalignment or muscle tightness makes them function unequally. Both types create asymmetrical loading of the SI joint, forcing one side to bear more weight and stress than the other. Real-world examples of apparent leg length discrepancy are common. A person with tight hip flexors on one side, for instance, might unconsciously hike that hip higher or lean to one side while standing, effectively shortening that leg functionally.
Over months or years, this asymmetry can irritate the SI joint on the loaded side, creating pain that feels centered in the lower back but actually originates at the sacroiliac joint. A physical therapist can assess both true and apparent discrepancies through palpation and measurement. The limitation of addressing leg length discrepancy alone is that it doesn’t always resolve SI joint pain, especially if other factors are also present. A patient with both a genuine leg length difference and occupational overuse, for instance, may need to address both issues simultaneously. Shoe lifts or orthotics can help correct apparent discrepancies, but true leg length differences sometimes require referral to an orthopedic specialist for evaluation.
Occupational and Athletic Overuse in Modern Work and Sport
Many occupations and sports place repetitive or prolonged stress on the SI joint, and this cause is increasingly recognized as driving SI joint pain in adults over 30. Occupational overuse occurs in people who spend hours in positions that stress the joint—construction workers, nurses, teachers who stand all day, and desk workers who sit asymmetrically. Athletic overuse, meanwhile, affects runners, cyclists, golfers, and others whose sports involve repetitive twisting, turning, or impact loading through one leg. Repetitive microtrauma is the mechanism at work here: small, cumulative injuries that individually might go unnoticed eventually add up to joint irritation and pain. A runner who increases weekly mileage too quickly might develop SI joint pain that gradually worsens over weeks.
A construction worker leaning heavily on one side while operating equipment for eight hours daily creates asymmetrical loading that compounds over years of work. Both scenarios lead to SI joint pain that develops slowly and sometimes frustratingly, since the person can’t pinpoint a specific moment when the injury occurred. A key comparison worth noting is that this cause is often preventable through technique modification, equipment changes, or work ergonomics adjustments. A cyclist who adjusts saddle height or cleat positioning, or an office worker who corrects their sitting posture and takes frequent movement breaks, may be able to prevent SI joint problems entirely. The challenge is recognizing these risk factors before pain develops.
Pregnancy, Hormonal Changes, and Inflammatory Arthritis
Pregnancy places unique mechanical stress on the sacroiliac joint as the pelvis widens and ligaments loosen under the influence of the hormone relaxin, preparing for childbirth. The added weight of pregnancy, combined with changes in gait and posture, can stress the SI joint beyond its normal tolerance and create pain during pregnancy or in the postpartum period. While pregnancy-related SI joint pain often resolves after delivery, some women experience persistent dysfunction that becomes a long-term vulnerability. Women are more commonly affected by SI joint pain overall compared to men, a difference partly explained by pregnancy but also by biomechanical and possibly hormonal factors that predispose women to SI joint dysfunction more broadly.
For women over 30 who’ve had pregnancies, the SI joint may have been stressed or injured during pregnancy and never fully recovered, setting the stage for pain when additional stressors are added later in life. Inflammatory arthritis conditions, including sacroiliitis and other seronegative spondyloarthropathies, can cause inflammation specifically in the sacroiliac joints. Unlike mechanical causes of SI joint pain, inflammatory arthritis requires different treatment approaches—often biologics or other disease-modifying drugs rather than physical therapy alone. If someone over 30 develops sudden SI joint pain accompanied by morning stiffness, fatigue, or other systemic symptoms, inflammatory arthritis should be considered alongside mechanical causes.
Trauma and the Long-Term Consequences of Pelvic Injuries
Falls, motor vehicle accidents, and direct impacts to the pelvis can damage the SI joint acutely, sometimes leading to chronic pain even after the initial injury heals. A person might experience SI joint trauma in their 20s or 30s, recover with rest, and then many years later find that their SI joint is vulnerable to re-injury or susceptible to pain when stress is placed on it. The joint simply never regains its full resilience after significant injury.
For example, a person who fell heavily on their buttock during a skiing accident at age 28 might experience acute pain that resolved over several months. However, if they develop occupational overuse or gain weight that shifts their center of gravity at age 45, that previously injured SI joint may become symptomatic again—a delayed consequence of the original trauma that the person might not initially connect. This pattern of initial recovery followed by later vulnerability is common with SI joint injuries.
The Growing Recognition of SI Joint Pain Among Healthcare Providers
Historically, sacroiliac joint pain was underappreciated by many clinicians who focused on the lumbar spine or hip as sources of lower back pain. Over the past two decades, however, there’s been tremendous growth in the appreciation and treatment of SI joint complex pain among medical professionals.
More doctors now understand that the SI joint is a common source of mechanical lower back pain, leading to increased diagnosis and more targeted treatment options. This increased recognition explains part of why SI joint pain appears to be increasing in prevalence—it’s not necessarily that more people have the condition now, but rather that more healthcare providers are diagnosing it correctly rather than misattributing the pain to other spinal structures. Patients who might have been told 15 years ago that their pain was “degenerative disc disease” might receive an SI joint diagnosis today with the same symptom pattern, simply because awareness has improved among clinicians.
Conclusion
The eight causes of SI joint pain increasing in adults over 30—age-related degenerative changes, previous spine surgery, leg length discrepancy, occupational and athletic overuse, pregnancy-related stress, inflammatory arthritis, osteoarthritis, and trauma—reflect both the aging process and the modern lifestyle factors that place increasing stress on this critical joint. Understanding these causes can help you recognize SI joint pain when it develops and guide more productive conversations with your healthcare provider about evaluation and treatment.
If you’re experiencing lower back pain that concentrates on one side, worsens with prolonged standing or certain activities, or doesn’t improve with typical back pain treatments, SI joint dysfunction may be worth investigating. Given that 25 percent of people with chronic low back pain have SI joint involvement, and an estimated 10 million American adults are potentially affected, you’re far from alone. Discussing SI joint pain risk factors and diagnostic possibilities with your doctor is a practical next step toward identifying the true source of your pain and finding appropriate treatment.
