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Conditions

Understand what's causing your hip or knee pain

Clear, surgeon-authored guides to the conditions we treat — what they feel like, why they happen, and the full range of options, from nonsurgical care to replacement when the time is right. Written and medically reviewed by Matthew Harb, M.D.

Common Symptoms

Noticing something but not sure what it is? Start here — these guides explain what may be behind a common symptom and what to do next.

Knee

Knee Pain Going Down Stairs: What It Means and What to Do

When a patient tells me their knee hurts going down stairs, the most common thing I see is a more severe problem behind the kneecap, often arthritis there. Going down pulls on the kneecap harder than going up. Here’s why, how to stay safe on stairs in the meantime, and when it’s time to come in.

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Hip

Hip Pain at Night: What It Means When It Wakes You Up

When a patient tells me their hip wakes them up at night, I take it seriously. Night pain usually means the symptoms are severe, most often arthritis that has become bone-on-bone. Here’s what hip pain at night usually means, how I sort out where it’s coming from, and what to do about it.

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Knee

Knee Swelling: What Causes a Swollen Knee and What to Do

When a patient tells me their knee is swollen, my first question is how it happened: was it an injury, or has it been building for a while? That history points to the cause. Here’s what usually makes a knee swell, what the fluid actually is, how I check for it, why I rarely drain it, and the two signs that mean you should be seen right away.

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Knee

Meniscus Tear or Arthritis? Why Your Knee Pain May Not Be What You Think

Many adults arrive at my office with knee pain, an MRI report listing a meniscus tear, and the assumption that an arthroscopy will fix it. Sometimes that’s right. Often it isn’t — because the meniscus tear is incidental to an underlying arthritis that arthroscopy can’t address. Telling these two situations apart is one of the most important decisions in knee care.

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Hip

Hip Labral Tear or Arthritis? Why Your Hip Pain May Not Be What You Think

Patients regularly arrive in my office with hip pain, an MRI report listing a labral tear, and the assumption that hip arthroscopy will fix it. Sometimes that is the right answer. Often it is not — because the labral tear is part of an underlying arthritic or impingement process that scope alone cannot address. Telling these situations apart is one of the most important decisions in hip care.

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Hip

Hip Stiffness: Causes, What It Means, and When to Have It Evaluated

Hip stiffness is one of the most common — and most overlooked — early signs of a hip-joint problem. Patients often dismiss it as "getting older" until functional limitations start to add up: putting on socks, getting out of a car, crossing a leg. Understanding what your hip stiffness is telling you is the first step toward the right plan, and surgery is rarely the first step.

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Hip

Hip Pain When Walking: Causes, What It Means, and When to Have It Evaluated

Hip pain when walking is one of the earliest — and most reliable — signals that something is changing in the hip joint. Walking loads the joint cyclically, several times your body weight per step, so a hip that handles standing comfortably can still hurt on a long walk. Identifying the cause is the first step toward the right plan, and surgery is rarely the first step.

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Knee

Swelling or a Lump Behind the Knee: What It Usually Is

A lump behind the knee is usually a Baker’s cyst: fluid from inside the knee collecting in the back of it. In my practice, other causes like a swollen lymph node, a lipoma or a tumor are rare. The cyst usually isn’t the real problem. It’s a sign the knee is making extra fluid, most often from arthritis or a meniscus tear, so I treat what’s happening inside the knee rather than drain the cyst.

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Knee

Knee Pain at Night: What It Means When It Wakes You Up

When a patient tells me their knee wakes them up at night, it’s usually a sign of severe arthritis. Once arthritis is affecting your sleep, it’s affecting your quality of life, and it’s time to come in. Here’s what knee pain at night usually means, why I’m careful about the pillow under the knee, and how to sleep in the meantime.

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Knee

Knee Stiffness: Why Your Knee Won’t Straighten or Bend

When a patient tells me their knee is stiff, it usually means it has lost some ability to straighten, to bend, or both. In arthritis, the biggest reason is usually swelling inside the knee, along with bone-on-bone wear that physically blocks it. Here’s what knee stiffness usually means, the pillow habit that makes it worse, and why keeping the knee moving matters, especially if surgery is ever in your future.

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Knee

Knee Pain When Walking: Causes, What It Means, and When to Have It Evaluated

Walking loads the knee several times your body weight with every step, thousands of times a day, so it is often where a knee problem shows itself first. Two things narrow the cause quickly: where the pain sits, and when during the walk it appears. And there is no fixed distance that means you need surgery — plenty of people walk a long way and still need a knee replaced.

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Knee

Knee Giving Way: Why It Buckles and What to Do

When a patient tells me their knee gives way, they usually think they’ve torn something. Most of the time they haven’t. The most common reason is pain making the thigh muscle shut off for a moment, so the knee buckles. Here’s how I tell that apart from a torn ligament or meniscus, why stairs are where it happens, why a fall is the real danger, and what helps.

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Knee

Bone on Bone Arthritis: Do You Need Knee Replacement Surgery?

If you’ve been told you have “bone-on-bone” arthritis, the first question is usually whether you need a knee replacement. The answer may surprise you: not necessarily. A severe X-ray is only part of the picture — what matters far more is how the arthritis is affecting your life. We treat patients, not X-rays.

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Diagnoses & Conditions

In-depth, surgeon-authored guides to the specific conditions behind hip and knee pain — and the full range of treatment options.

Hip

Hip Osteoarthritis: Symptoms & Treatment

Hip osteoarthritis is the gradual wearing of the cartilage in the hip joint. It can’t be reversed — but it can be managed well, often for years, with the right plan. Here is how it feels, how it tends to progress, and the full range of options, from activity changes and injections to replacement when the time is right.

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Knee

Knee Osteoarthritis: Symptoms & Treatment

Knee osteoarthritis is the gradual wearing of the cartilage that cushions the knee. It can’t be reversed — but it can be managed well, often for years, with the right plan. Here is how it feels, how it tends to progress, and the full range of options, from activity changes and injections to partial or total replacement when the time is right.

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Hip

Avascular Necrosis (AVN) of the Hip: Stages, X-Rays & Treatment

Avascular necrosis (AVN) of the hip happens when the ball of the hip loses its blood supply and the bone begins to die. It’s staged by what X-rays and MRI show. Early AVN can often be watched. Once the bone has collapsed, a hip replacement is the best operation: it’s predictable, the recovery is short, and AVN can’t come back in a replaced hip.

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Hip

Hip Impingement (FAI): A Cause of Labral Tears and Early Hip Arthritis

Femoroacetabular impingement — FAI — is an anatomic shape mismatch between the ball and socket of the hip that causes the bone to pinch the labrum and articular cartilage during normal motion. Over years, that abnormal loading produces labral tears and accelerates the development of hip arthritis. Understanding where you are on that continuum — and treating the right thing at each stage — is what makes the difference.

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Hip

Hip Dysplasia in Adults: Symptoms, Treatment & Hip Replacement

Hip dysplasia means the hip is shaped in a way that loads it unevenly, most often a shallow socket. Many adults don’t learn they have it until their hip starts hurting in their 20s, 30s, or 40s. Here’s what it feels like, what the options are, and why, for most adults with pain and arthritis, a hip replacement is the most reliable answer.

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Knee

Post-Traumatic Arthritis: When an Old Injury Catches Up

Post-traumatic arthritis is arthritis that develops in a joint after a prior injury — sometimes decades later. ACL tears, meniscus injuries, fractures, and dislocations all change how the joint loads and wears, and over time those changes produce the same arthritis process that happens with age-related osteoarthritis, often earlier and often in just the injured joint.

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Hip

Hip Bursitis: Lateral Hip Pain (Trochanteric/Abductor) and Iliopsoas

“Hip bursitis” actually describes two very different problems. The common one is lateral hip pain — trochanteric (abductor) bursitis, now better understood as greater trochanteric pain syndrome (GTPS) — pain on the outside of the hip that makes it hard to sleep on that side. The less common one is iliopsoas bursitis, felt in the front of the hip and groin. Both are usually treated without surgery, and the most important step is making sure the pain isn’t actually coming from the lower back or from inside the hip joint itself.

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Knee

Bow Legs and Knock Knees: Varus and Valgus Deformity of the Knee

Bow-legged is varus; knock-kneed is valgus. Either can be something you were born with or something arthritis produced by wearing one side of the knee away. Varus is far more common. Valgus tends to advance faster and is more demanding to correct. In most cases the alignment is corrected during the knee replacement itself rather than with a separate osteotomy.

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Not sure what’s causing your pain?

Schedule a consultation with Dr. Harb to discuss your hip or knee and build a plan to get you back to the activities you love.

Not ready to book? Read how to choose a hip or knee surgeon