Chiropractors use a combination of hands-on feel, visual observation, patient history, and sometimes imaging to pinpoint which joints need adjustment. No single test gives the full picture. Instead, practitioners layer several assessment methods together to build a map of where your spine or joints are restricted, misaligned, or causing problems.
Feeling for Restricted Joints by Hand
The primary tool is the chiropractor’s own hands. The technique most widely used is called motion palpation, where the practitioner manually moves each spinal segment to assess how freely it glides in different directions. Spinal joints follow predictable movement patterns, and when a segment resists or moves less than expected, it signals a restriction worth addressing. Practitioners are looking for gross hypomobility (a joint that clearly doesn’t move enough) rather than trying to detect tiny, subtle shifts.
Interestingly, lighter touch tends to produce better results. Research published in the Journal of Contemporary Chiropractic notes that using less force during palpation actually enhances the examiner’s ability to sense what’s called “first noticeable displacement,” the initial give of a joint when pressure is applied. The practitioner’s fingertip nerve endings are more sensitive to that first movement when they aren’t pressing hard.
Before moving joints, chiropractors also use static palpation, pressing gently into the muscles and tissues alongside the spine to find points of tenderness, swelling, or unusual tightness. A spot that produces a sharp pain response or feels noticeably different from the tissue above and below it draws attention as a potential problem area. These tender points often correspond to segments that also show restricted motion.
What They Look for Visually
Before touching your spine, most chiropractors observe your posture from the front, back, and side. Specific markers they check include whether one shoulder sits higher than the other (measured by clavicle angle), whether your pelvis tilts to one side, whether your head drifts forward relative to your shoulders, and whether the center of your upper spine lines up with your sacrum. A forward head posture, for example, tells the chiropractor that the cervical spine is bearing load differently than it should, which narrows down where compensatory restrictions are likely hiding.
Gait, or the way you walk, also provides clues. An uneven stride or a hip that drops on one side can point to pelvic imbalance or lower lumbar dysfunction that a hands-on exam can then confirm.
The Leg Length Check
You may have had a chiropractor compare the length of your legs while you lie face down. This isn’t checking for an actual bone length difference in most cases. Instead, it’s a functional test. When the pelvis is tilted or the muscles on one side of the spine are tighter than the other, one leg can appear to draw slightly upward, making it look shorter.
Upper cervical chiropractors (those who focus on the top two vertebrae) use this test differently. They treat a functional short leg as an indirect sign that the atlas, the top vertebra, is out of its ideal position. The reasoning is that misalignment at the top of the spine creates a neurological imbalance that increases muscle tone unevenly, pulling one leg up. Outside of upper cervical work, prone leg checks are more commonly used to assess pelvic torsion and determine which side of the pelvis needs attention.
When X-Rays Are Used
Not every chiropractor takes X-rays, and guidelines vary within the profession. Some practitioners reserve imaging for cases with red flags like a history of trauma, suspected fracture, or signs of serious disease. Others consider radiography a routine part of biomechanical assessment, arguing that certain alignment problems simply can’t be seen without imaging.
What X-rays reveal that hands cannot includes the exact degree of vertebral rotation or translation, disc space narrowing, bone density changes, and structural anomalies that might change how a chiropractor delivers force. One study examining spinal anomalies found that conditions like spondylolisthesis (where one vertebra slips forward on another) appeared in 8% of patients, degenerative joint disease in 24%, and transitional segments (where the lowest lumbar vertebra partially fuses with the sacrum) in 10%. None of these can be detected by touch alone, and all of them can change whether and how a segment should be adjusted.
Weight-bearing X-rays, taken while you’re standing, are particularly valued because they show how your spine behaves under the load of gravity, revealing alignment distortions that disappear when you lie down.
Thermal Scanning
Some chiropractors, particularly those focused on the upper cervical spine, use a device that measures skin temperature along both sides of your spine. The theory rests on a straightforward chain of logic: skin temperature reflects blood flow, blood flow is controlled by the autonomic nervous system, and if the nervous system is functioning well, skin temperature should fluctuate naturally as your body adapts to the environment.
The practitioner takes multiple readings several hours apart. If the temperature pattern changes between scans, autonomic function is considered normal. If the same asymmetric pattern shows up repeatedly, it suggests the nervous system isn’t adapting properly, pointing to a spinal segment that may need adjustment. This approach remains more common in specific chiropractic techniques than in the profession broadly.
Muscle Testing
Applied kinesiology is a diagnostic approach where the chiropractor tests the strength of specific muscles while applying a challenge, like pressing on a vertebral segment or having you hold a particular position. The idea is that a muscle will temporarily weaken when the nervous system is stressed by contact with a dysfunctional joint. If pushing on a vertebra in a certain direction causes a previously strong muscle to give way, that segment and direction become the target for adjustment.
This method is more controversial than other assessment tools. Research on its reliability has been mixed. One study found poor agreement between different examiners performing the same vertebral challenge test, meaning two practitioners could reach different conclusions about the same spine. Chiropractors who use this technique often combine it with other findings rather than relying on it in isolation.
How These Methods Work Together
In practice, a chiropractor rarely relies on a single method. A typical visit might start with a posture check that reveals a high right shoulder and forward head position, followed by motion palpation that finds restricted segments in the mid-cervical and upper thoracic spine, confirmed by tenderness on static palpation at those same levels. If X-rays were taken at the initial visit, the chiropractor already knows whether any anomalies at those levels require a modified approach.
The adjustment itself is then targeted based on all of this information. Imaging and assessment together inform the direction, depth, and force of the thrust. A segment that’s rotated to the right, for instance, would typically receive a corrective force from a specific angle rather than a generic push. The goal is to restore motion to the restricted segment while respecting the anatomy underneath.
Safety Screening Happens First
Before deciding where to adjust, chiropractors also screen for reasons not to adjust. Certain conditions make spinal manipulation dangerous at specific segments or across the entire spine. These include acute fractures, osteoporosis, active infections, tumors, connective tissue disorders, rheumatoid arthritis, vascular abnormalities, and recent surgery. Symptoms like dizziness, visual disturbances, difficulty swallowing, or facial numbness triggered by neck movement are red flags that signal the cervical spine should not be manipulated until further evaluation rules out vascular problems. This screening process is as important as the assessment itself, because identifying where not to adjust protects you from the small but real risks of manipulation in vulnerable areas.