Understanding the Causes of Knee Pain

Knee pain is one of the most common complaints that brings patients to Leg Pain and Vascular Institute in Houston, TX. It affects people of all ages, from active adults who push through morning stiffness to older patients who have stopped doing the things they love because every step hurts. Understanding what is actually causing your knee pain is the first step toward finding a solution that works.

Dr. Bilal Anwer, a Stanford Fellowship-trained and CAQ Board Certified Vascular and Interventional Radiologist, sees patients across Greater Houston who have often spent months or years trying to manage knee pain without getting to the root cause. This article explains the most common causes of knee pain, how to recognize when it has crossed a threshold that warrants specialist evaluation, and what options exist beyond pain medication and surgery.

The Most Common Causes of Knee Pain

Knee pain rarely has a single cause. In most cases, several factors are working together. Understanding which category your pain falls into helps guide the right treatment approach.

Osteoarthritis

Osteoarthritis is the leading cause of chronic knee pain in adults over 50, though it increasingly affects younger people as well. It develops when the cartilage that cushions the joint gradually wears down, causing bones to rub against each other. The result is pain, stiffness, swelling, and a gradual loss of range of motion.

Osteoarthritis does not follow a predictable schedule. Some patients have significant structural damage on imaging but moderate symptoms. Others have severe daily pain that does not match what an X-ray shows. This disconnect between imaging and symptoms is one reason why treatment decisions should be based on how the patient feels and functions, not just on what a scan reveals.

Common signs of osteoarthritis in the knee include stiffness after sitting or sleeping, pain that worsens with stairs or prolonged walking, a grinding or clicking sensation in the joint, and swelling that comes and goes. Over time, many patients notice their knee feels warm or puffy even without a recent injury.

Ligament and Meniscus Injuries

Ligament tears, most commonly of the ACL or MCL, and meniscus injuries are frequent in both athletes and people who experience a sudden twisting movement or fall. These injuries typically cause sharp pain at the time of the event, followed by swelling and instability in the joint.

Meniscus tears in particular are common in middle-aged adults and can occur without any dramatic injury at all. A simple movement, stepping off a curb awkwardly or rotating while standing, is sometimes enough to tear a meniscus that has already begun to degenerate. This type of tear often causes pain on one side of the knee, locking or catching sensations, and difficulty fully straightening or bending the leg.

Bursitis and Tendinitis

Bursitis is inflammation of the small fluid-filled sacs that cushion the knee joint. It causes a localized aching or burning pain, often on the front or inner side of the knee, and is common in people who kneel frequently or who have sustained a direct blow to the joint. Tendinitis, particularly of the patellar tendon, is an overuse injury common in runners and cyclists that causes pain just below the kneecap.

These conditions respond well to rest, physical therapy, and anti-inflammatory treatment in most cases. When they become chronic, however, they are often a sign of an underlying structural or vascular issue that has not been addressed.

Referred Pain from the Hip or Lower Back

Not all knee pain originates in the knee. The hip and lumbar spine share nerve pathways with the knee, and conditions like hip arthritis or a herniated disc can produce pain that is felt entirely in the knee joint. Patients are sometimes surprised to discover that treating their hip or back resolves knee symptoms they had attributed to the joint itself.

If your knee pain does not follow a clear pattern related to activity, if it is difficult to point to exactly where it hurts, or if it comes with hip stiffness or lower back pain, this possibility is worth discussing with a specialist.

Vascular Causes of Knee Pain

One of the most frequently overlooked causes of chronic knee pain is abnormal blood vessel activity within and around the joint. In knees affected by arthritis, the body generates new blood vessels in an attempt to repair damaged tissue. These new vessels bring with them nerve fibers that increase pain sensitivity in the joint. The more new vessel growth there is, the more pain signals the knee generates, regardless of how much cartilage remains.

This vascular component is why some patients with moderate arthritis have severe pain while others with more advanced structural damage report manageable symptoms. It is also the mechanism behind Genicular Artery Embolization (GAE), a minimally invasive procedure that addresses the vascular driver of knee pain rather than the joint structure itself. Dr. Anwer performs GAE at both Houston-area clinic locations as an outpatient procedure, with most patients returning to normal activity within 24 to 48 hours.

How Arthritis Differs from Injury-Related Knee Pain

Distinguishing arthritis from injury-related pain matters because the treatment approach is fundamentally different. Injury-related pain typically has a clear onset, a specific location, and a connection to a particular movement or event. Arthritis pain tends to develop gradually, affect a broader area of the joint, and worsen progressively over months or years.

A few patterns that suggest arthritis rather than injury:

• Pain that is worse in the morning and improves with movement, then worsens again after extended activity
• Stiffness that takes more than 30 minutes to ease after waking
• Bilateral symptoms, meaning both knees are affected even if one is worse
• Gradual worsening over time with no single precipitating event
• Swelling that is chronic rather than acute

Injury-related pain, by contrast, tends to be more localized, often involves instability or locking, and is usually linked to a specific incident. Many patients have both: a previous injury that was never fully treated, followed years later by the development of secondary arthritis in the same joint.

When Conservative Treatment Stops Working

Most knee pain is managed initially with rest, physical therapy, anti-inflammatory medications, and activity modification. These approaches are appropriate first steps and often provide meaningful relief, particularly for mild to moderate symptoms.

The challenge arises when conservative treatment stops producing results. Patients often reach a plateau where physical therapy no longer moves the needle, medications cause side effects or are not sufficiently effective, and cortisone injections provide shorter and shorter periods of relief with each round. At this point, continuing the same approach and expecting a different outcome is not a realistic plan.

Signs that conservative treatment may have reached its limit include:

• Cortisone injections that used to provide three to six months of relief now lasting only a few weeks
• Pain that interrupts sleep on a regular basis
• Significant reduction in walking distance compared to one or two years ago
• Avoidance of activities you previously enjoyed because of pain
• Pain at rest, not just during activity

Reaching this point does not automatically mean knee replacement surgery is the next step. For many patients, particularly those who are not ideal surgical candidates or who want to delay or avoid surgery, there are minimally invasive options that have not yet been explored.

When to See a Specialist

Many people tolerate knee pain for far longer than necessary because they assume the only options are to manage it or have surgery. Seeking a specialist evaluation earlier opens up a broader range of treatment options and, in many cases, prevents the condition from advancing to a stage where more aggressive intervention becomes unavoidable.

Consider scheduling a consultation with Dr. Anwer at Leg Pain and Vascular Institute if:

• Your knee pain has persisted for more than three months despite conservative treatment
• You have been told you need knee replacement surgery but want to explore alternatives first
• Previous injections have stopped working or are no longer an option
• Your pain is affecting your sleep, work, or daily activities
• You have been told your arthritis is not severe enough for surgery but your pain is significant

Dr. Anwer takes a different approach to knee pain than most providers. As a dual board-certified interventional radiologist, he evaluates the vascular component of joint pain that many standard orthopedic assessments do not address. For patients with chronic knee pain driven by arthritis and inflammation, Genicular Artery Embolization (GAE) offers a pathway to meaningful, lasting relief without surgery, hospital admission, or a lengthy recovery.

A Non-Surgical Option Worth Knowing About

GAE works by precisely reducing blood flow to the inflamed vessels surrounding the arthritic knee joint. By targeting the new blood vessels that have grown into the joint in response to arthritis, the procedure reduces the pain signals being generated without removing or replacing any part of the joint. The procedure is performed through a pinhole in the wrist or groin, takes approximately 45 minutes, and is carried out entirely as an outpatient. No general anesthesia is required and most patients go home the same day.

GAE does not reverse cartilage damage. What it does is address the vascular and inflammatory driver of pain, which is often the primary reason a knee with moderate arthritis generates severe symptoms. Many patients experience significant pain reduction within two to four weeks of the procedure, with results that have been shown to last well beyond what repeated cortisone injections typically provide.

If you are not yet sure whether GAE is appropriate for your situation, the best starting point is a consultation. Dr. Anwer reviews imaging personally and will give you a clear, honest assessment of whether the procedure is likely to help based on your specific anatomy and symptom profile.

Frequently Asked Questions

What is the most common cause of knee pain in adults over 50?
Osteoarthritis is the most common cause. It develops as the cartilage in the knee joint gradually wears down, causing pain, stiffness, and inflammation. The vascular component of arthritis, specifically the growth of new blood vessels into the joint, is a significant driver of pain that is often not addressed by standard treatments.

Can knee pain be caused by something other than the knee itself?
Yes. Hip arthritis and lumbar spine conditions can refer pain to the knee through shared nerve pathways. Poor circulation from arterial disease can also cause leg and knee pain that mimics joint problems. A thorough evaluation should consider these possibilities, particularly when pain does not respond to treatments directed at the knee joint.

Is knee replacement surgery the only option for severe arthritis?
No. Genicular Artery Embolization (GAE) is a minimally invasive procedure performed by Dr. Anwer at Leg Pain and Vascular Institute that addresses the inflammatory and vascular driver of knee arthritis pain. It is an outpatient procedure with same-day recovery and no general anesthesia. Many patients who are not ready for or do not want surgery have experienced significant, lasting pain reduction with GAE.

How do I know if my knee pain is from arthritis or an injury?
Arthritis pain typically develops gradually over months or years, affects a broad area of the joint, and is worse after rest and extended activity. Injury-related pain usually has a specific onset event, a more localized location, and may involve instability or locking. Many patients have both: a prior injury that contributed to early-onset arthritis in the same joint. A specialist evaluation including imaging is the most reliable way to distinguish between the two.

What should I do if cortisone injections have stopped working for my knee?
Cortisone injections become less effective over time for many patients with chronic arthritis. When they stop providing meaningful relief, it is a signal to explore other options rather than continuing the same approach. A consultation with Dr. Anwer at Leg Pain and Vascular Institute can determine whether GAE or another minimally invasive approach is appropriate for your specific situation. No referral is required to book an appointment.

Take the Next Step

Knee pain that has not responded to conservative treatment deserves a fresh evaluation by a specialist who can look beyond the standard options. At Leg Pain and Vascular Institute, Dr. Anwer sees patients from across Greater Houston, including Sugar Land, Katy, The Woodlands, Pearland, Pasadena, Cypress, and Webster, at two convenient locations.

Same-day appointments are available. No referral is required. Learn more about knee arthritis treatment and GAE or call 713-242-1139 to speak with our team.