During an SI (sacroiliac) joint examination, physical therapists systematically assess the sacroiliac joint through a combination of patient history, visual observation, hands-on palpation, movement tests, and specialized orthopedic tests designed to identify whether the joint is the source of pain or dysfunction. A therapist typically begins by asking about the location and nature of pain, what activities aggravate symptoms, and whether the patient has experienced trauma or falls—information that helps narrow the focus before physical testing begins. For someone with balance concerns or a history of falls, understanding SI joint stability becomes particularly important, as dysfunction here can compromise the foundation that supports upright posture and lower body movement.
This exam is especially relevant for older adults or those with neurological changes, since SI joint issues can contribute to gait instability, difficulty with stairs, and increased fall risk. The therapist will evaluate joint mobility, muscle strength in the hips and core, and the joint’s ability to provide stability during standing and walking. By the end of this examination, the therapist can determine whether SI joint dysfunction is present and, if so, develop a treatment plan that may include targeted exercises, manual therapy, bracing, or movement retraining.
Table of Contents
- How Physical Therapists Evaluate Sacroiliac Joint Positioning and Mobility
- Special Tests That Identify SI Joint Dysfunction and Instability
- Assessment of Core Strength and Hip Muscle Function
- Gait Analysis and Functional Movement Assessment
- Assessment of Pelvic Alignment and Postural Patterns
- Sacroiliac Joint Stress Tests and Provocation Maneuvers
- Integration of Neurological Screening and Fall Risk Assessment
- Conclusion
How Physical Therapists Evaluate Sacroiliac Joint Positioning and Mobility
The first hands-on component of an SI joint exam involves palpation—using skilled touch to feel the position of bony landmarks and assess how the joint moves. The therapist identifies the sacroiliac joint itself by locating the posterior superior iliac spine (PSIS), a bony bump at the back of the pelvis that serves as an anatomical reference point. By palpating on both sides, the therapist can detect whether one side sits higher or lower than the other, which may indicate pelvic asymmetry or joint dysfunction. For example, a patient with a right SI joint sprain might show subtle misalignment where the right PSIS appears higher than the left.
Beyond simply feeling bony landmarks, the therapist will perform gentle mobilization tests to assess how freely the joint moves. The examiner may push gently on specific points to see whether movement is restricted or hypermobile (too loose). In some cases, patients with generalized ligament laxity—such as those with connective tissue changes—may have SI joints that are overly mobile, which paradoxically can cause pain and instability rather than limited movement. The therapist compares findings from both sides, since asymmetry in how the joints move often points to the problem area.
Special Tests That Identify SI Joint Dysfunction and Instability
Physical therapists use specific orthopedic tests that have been studied for their ability to indicate SI joint involvement. The FABER test (flexion, abduction, external rotation) involves positioning the patient’s leg to stress the SI joint and hip in a particular way; pain with this test may suggest SI joint pathology. The FADIR test (flexion, adduction, internal rotation) stresses the joint differently, and a positive response helps differentiate between hip and SI joint problems. However, it’s important to note that these tests are not perfectly specific—a positive FABER or FADIR test can indicate hip joint problems rather than SI joint issues, so the therapist considers the entire clinical picture.
The Thigh Thrust test (also called the SI shear test) applies a direct compressive force through the femur while the patient lies on their side, attempting to provoke SI joint pain if instability is present. Similarly, the SI Compression test pushes the two sides of the pelvis together to assess joint stiffness, while the Distraction test gently pulls the pelvis apart. A person with significant SI joint instability might experience increased pain with the Distraction test but relief with Compression test, suggesting that the joint needs more stability. Additionally, dynamic tests like Single Leg Stance or Single Leg Hop help the therapist observe whether the pelvis remains stable during weight-bearing, revealing functional weakness or compensation patterns that develop when the SI joint is not properly supported.
Assessment of Core Strength and Hip Muscle Function
An often-overlooked but critical part of the SI joint exam is evaluating the muscles that support and stabilize the joint. The gluteal muscles (especially the gluteus medius), deep abdominal core muscles, and lumbar multifidus all work together to maintain pelvic stability. The therapist tests the strength of these muscles through specific movements: resisted hip abduction, hip extension, and trunk rotations. A patient might perform a single-leg stance while the therapist observes whether the pelvis droops on the non-stance side—a sign of weak hip abductors.
For older adults or those with neurological changes, muscle weakness in these stabilizers is common and may be a primary driver of SI joint pain. For instance, someone recovering from a stroke or with Parkinson’s disease may have asymmetrical weakness on one side, which places extra stress on the SI joint during walking. The therapist evaluates not just whether muscles are weak, but whether they activate at the right time during movement—a concept called motor control. Poor coordination between the deep core muscles and the larger hip muscles means the SI joint lacks the dynamic support it needs, even if overall strength is adequate.
Gait Analysis and Functional Movement Assessment
How a person walks reveals a great deal about SI joint function. During gait analysis, the therapist observes the pelvis for excessive dropping, rotation, or side-to-side shifting. A person with SI joint dysfunction often adopts a guarded gait pattern—shorter steps on the affected side, less trunk rotation, or a “waddling” pattern where the pelvis rocks excessively with each step. Comparing how the patient walks before and after treatment can help confirm that SI joint mobility or stability improvements are making a functional difference.
Functional tests complement gait observation: the therapist may ask the patient to climb stairs, sit down and stand up, or pick something off the floor while watching for pain or movement compensation. For someone with dementia or cognitive changes, understanding their baseline functional ability helps ensure that SI joint treatment focuses on movements and activities that matter in their daily life. A person living in a multi-story home needs stair climbing confidence; someone in an assisted-living facility may prioritize standing balance and walking distance. The therapist’s assessment is incomplete without understanding what activities the patient needs or wants to perform.
Assessment of Pelvic Alignment and Postural Patterns
Posture and pelvic alignment provide clues about chronic SI joint stress. The therapist observes the patient standing from the front, back, and side, noting whether the pelvis is level, tilted forward, or rotated. An anterior pelvic tilt (where the front of the pelvis tips downward) increases stress on the SI joint and lower back, while a posterior pelvic tilt (back of pelvis tipping down) changes the joint’s load distribution in a different way. Some postural patterns develop in response to pain—the body unconsciously shifts weight or changes alignment to unload an irritated joint—but over time these compensatory patterns can create new problems elsewhere.
For individuals with balance concerns related to neurological conditions, pelvic alignment directly affects the body’s center of gravity and stability. Someone with Parkinson’s disease or a history of stroke may have developed postural changes that secondarily stress the SI joints. Additionally, the therapist assesses symmetry in how the ribcage sits relative to the pelvis, since the thoracolumbar spine connects to the sacrum, and restrictions higher up in the spine can indirectly affect SI joint mechanics. One important limitation: postural assessment alone cannot definitively diagnose SI joint dysfunction, because posture changes for many reasons and some individuals maintain excellent upright posture despite significant SI joint pathology.
Sacroiliac Joint Stress Tests and Provocation Maneuvers
Beyond the well-known FABER and Thigh Thrust tests, therapists may use additional provocation tests to further confirm SI joint involvement. The Pelvic Tilt test involves having the patient lie supine and gently rock the pelvis to see whether this movement reproduces pain. The Sacral Thrust test applies direct pressure through the sacrum, attempting to compress the joint and provoke a response. The Standing Flexion test has the patient bend forward while the therapist observes whether one PSIS moves differently than the other, suggesting unilateral SI joint restriction.
These tests work best when performed as a cluster—no single test is 100% accurate on its own. A therapist who finds three or four positive tests clustered together, combined with consistent pain location and matching movement patterns, develops high confidence that the SI joint is involved. However, some patients have SI joint dysfunction without reproducing pain during these specific tests, particularly if the problem is more related to stability and motor control than to acute joint irritation. This is why clinical reasoning and the patient’s functional presentation matter as much as the test results themselves.
Integration of Neurological Screening and Fall Risk Assessment
For individuals referred to physical therapy with concern for neurological changes, cognitive decline, or fall risk, the SI joint assessment includes a broader view of how joint dysfunction affects balance and safety. The therapist observes whether SI joint instability contributes to balance loss or whether the patient leans excessively to one side. Tests like the Romberg test (standing with feet together and eyes closed) and the Functional Reach Test help quantify balance impairment and fall risk, factors that become especially important for aging adults or those with dementia-related changes.
Understanding SI joint stability also informs fall prevention strategies. A person with poor SI joint support may need a sacroiliac brace or belt to improve proprioceptive feedback (body awareness) and reduce pain during weight-bearing activities, ultimately making exercise and mobility safer. As research continues to evolve, therapists increasingly recognize that SI joint dysfunction in older adults often coexists with changes in balance, cognition, and sensory perception—areas of particular concern for individuals with neurological conditions. Treatment that addresses joint mechanics while also retraining balance and coordination offers the most comprehensive approach to restoring function and reducing fall risk.
Conclusion
A comprehensive SI joint examination by a physical therapist involves far more than a single test or observation. Through careful history-taking, palpation, specialized orthopedic tests, functional assessment, and evaluation of core stability and gait, the therapist builds a complete picture of how the sacroiliac joint contributes to pain, movement dysfunction, and falls.
For older adults or those with neurological changes, understanding SI joint function becomes part of a broader picture that includes balance, mobility confidence, and safety during daily activities. If you experience low back pain, pain at the buttock or hip, difficulty with stairs or uneven walking, or have concerns about falls and balance, a physical therapist evaluation can determine whether the SI joint is involved. Even if SI joint dysfunction is not the primary concern, addressing joint stability and core support often improves overall movement quality and reduces fall risk—outcomes that matter greatly for maintaining independence and quality of life as we age.
