Pain on the side of your knee when you walk usually comes from soft tissue irritation rather than a problem inside the joint itself. The most common culprits differ depending on whether the pain is on the outer (lateral) side or the inner (medial) side, but both tend to worsen with repetitive motion like walking because each step loads the same structures over and over. Narrowing down the location and character of your pain goes a long way toward identifying what’s going on.
Outer Knee Pain: The Usual Suspects
If the pain runs along the outside of your knee, the three most likely causes are iliotibial band syndrome, a lateral meniscus tear, or an injury to the lateral collateral ligament (LCL).
Iliotibial Band Syndrome
The IT band is a thick strip of connective tissue that runs from your hip down to just below the outer edge of your knee. When it gets tight or inflamed, it rubs against the bony bump on the outside of your thighbone with every step, producing a sharp, pinching pain. Walking downhill, running, and even climbing stairs can all set it off because these movements repeatedly bend and straighten the knee through the range where friction is highest.
Several factors make IT band syndrome more likely. Weak hip muscles that normally stabilize your pelvis can let the band tighten up. Feet that roll inward too much (overpronation) stretch the IT band and pull it closer to bone. Even worn-out shoes, having one leg slightly longer than the other, or bowed legs can contribute. This is one of the most common causes of outer knee pain in people who walk or run regularly.
Lateral Meniscus Tear
Each knee has two C-shaped pads of rubbery cartilage that sit between the thighbone and shinbone, acting as shock absorbers. The one on the outer side is the lateral meniscus. A tear here causes pain right along the outer joint line, and it often comes with a catching or locking sensation when you walk, as if something is briefly stuck inside the knee. Tears can happen from a sudden twist or pivot, but in people over 40, normal wear and tear can weaken the cartilage enough that even deep squatting or an awkward step is enough to cause a tear.
LCL Injury
The LCL is a ligament on the outer side of your knee that keeps the joint from bowing outward. It tears when excessive force pushes the knee inward, which is common in contact sports but can also happen from a bad fall. An LCL injury typically causes pain specifically over the ligament itself, and the knee may feel unstable or wobbly, especially when you change direction while walking.
Inner Knee Pain: Common Causes
Pain on the inner (medial) side of the knee when walking has its own set of causes, some of which overlap with outer knee problems.
Medial Meniscus Tear
The meniscus on the inner side tears the same way as its outer counterpart: forceful twisting, pivoting, or degenerative wear over time. The pain sits right along the inner joint line and may come with the same mechanical symptoms like catching, locking, or a sensation that the knee is giving way. Obesity increases the risk because extra body weight accelerates cartilage breakdown. Activities that involve aggressive pivoting, such as tennis or basketball, are particularly risky.
Pes Anserine Bursitis
A small fluid-filled sac called the pes anserine bursa sits on the inner side of your shinbone, about two to three inches below the joint line. When it gets inflamed, the pain and tenderness settle in that specific spot, lower than where a meniscus tear would hurt. This distinction matters because the two conditions feel similar enough that imaging is often needed to tell them apart. Pes anserine bursitis is more common in runners, people with tight hamstrings, and those with osteoarthritis.
MCL Strain
The medial collateral ligament mirrors the LCL on the opposite side. It resists forces that push the knee outward. A strain or partial tear causes localized pain along the inner edge of the knee and may make the joint feel loose. Unlike bursitis, the tenderness sits right along the ligament rather than below the joint.
How Your Feet Affect Your Knees
The way your foot hits the ground with each step directly influences which side of your knee absorbs more stress. Overpronation, where the arch collapses inward too much, pulls the lower leg into a position that increases tension on the IT band and the outer knee. Supination, where your weight rolls onto the outer edges of your feet, shifts stress inward and can overload the medial compartment. Both patterns are common and often go unrecognized for years.
If your walking shoes are unevenly worn, that’s a clue. Shoes that are flattened on the inner heel suggest overpronation. Shoes worn down on the outer edge suggest supination. Correcting foot mechanics with supportive footwear or insoles can reduce knee pain significantly because it addresses the root cause rather than just the symptom.
How to Tell These Conditions Apart
Location is the single most useful clue. Pain right along the joint line, on either side, points toward a meniscus tear or ligament issue. Pain that spans from the hip to the outer knee, especially with a burning or pinching quality, suggests the IT band. Pain two to three inches below the inner joint line suggests pes anserine bursitis.
Mechanical symptoms narrow things down further. If your knee catches, clicks, or locks during walking, a meniscus tear is likely. If it feels unstable or buckles, a ligament injury is more probable. If the pain is worst during the first few minutes of walking and then settles into a dull ache, bursitis or IT band irritation are strong possibilities.
A doctor can confirm the diagnosis with specific physical tests. For a suspected IT band problem, pressing on the outer knee while slowly straightening the leg reproduces the pain. For meniscus tears, rotating the lower leg while bending and extending the knee may produce a pop or click right at the joint line. Stress tests that push the knee sideways reveal ligament laxity. These exams take a few minutes and often give a clear answer without imaging, though an MRI may be ordered if the picture is uncertain.
What Helps Side Knee Pain
For most soft tissue causes, the initial approach is the same: reduce the load on the irritated structure and let inflammation settle. Cutting back on walking distance temporarily, icing the painful area for 15 to 20 minutes after activity, and wearing supportive shoes all help in the short term.
Targeted strengthening matters more than rest alone. For IT band syndrome, strengthening the hip muscles that control pelvic stability, particularly the muscles on the outer hip, reduces tension on the band. For inner knee pain from bursitis or mild ligament strain, strengthening the quadriceps and hamstrings helps stabilize the joint so the irritated tissue isn’t constantly under load. Foam rolling along the outer thigh can also relieve IT band tightness, though it’s often uncomfortable at first.
Meniscus tears have a wider range of outcomes. Small tears on the outer edge of the meniscus, which has better blood supply, can heal on their own with activity modification. Larger tears or those causing persistent locking may need surgical repair. Recovery from meniscus surgery varies, but most people return to normal walking within a few weeks and full activity within a few months.
Signs That Need Prompt Attention
Some knee symptoms warrant urgent evaluation. If your knee suddenly swelled up, you heard a popping sound at the time of injury, or the joint looks visibly deformed, get to an emergency room or urgent care. The same applies if you can’t bear weight at all or the pain is intense and unrelenting. If the pain is more of a persistent nuisance that interferes with sleep or daily tasks, schedule an appointment with your doctor rather than waiting it out.