Andrew B. Harris, MD · Last reviewed September 2026
Understanding what is causing your hip or knee pain is the first step toward feeling better. Below are patient guides to the most common questions, followed by explanations of the conditions Dr. Harris treats most often, and how he approaches each one.
Modern hip and knee replacements are also durable. Pooled registry and study data show the large majority still working two decades after surgery, and many considerably longer.1,2,3 Hip replacement has been described as the operation of the century4, and knee replacement is among the most effective treatments available for advanced knee arthritis.5
What exercise, weight, medication and injections actually do for arthritis, and what the evidence does not support.
Read the guide →The symptoms of hip arthritis, when surgery is considered, and what to try first.
Read the hip guide →The symptoms of knee arthritis, total versus partial knee replacement, and what to try first.
Read the knee guide →A realistic, week-by-week timeline: walking, driving, and returning to activity.
Hip recovery timeline →What to expect week by week, and why physical therapy is central to the result.
Knee recovery timeline →Select a topic to read more.
The hip is a ball-and-socket joint, with both surfaces covered in smooth cartilage that lets the ball glide inside the socket without pain. Osteoarthritis, the most common form of hip arthritis, is the gradual wearing away of that cartilage. As it thins, the smooth gliding surface is lost, and eventually bone rubs directly against bone.
Hip arthritis usually comes on slowly over months or years. Common signs include:
Hip osteoarthritis is driven by a mix of age, genetics, prior injury, and conditions present earlier in life such as hip dysplasia or a previous fracture. Inflammatory types of arthritis, such as rheumatoid arthritis, are caused by inflammation of the joint lining rather than simple wear and can behave differently.
Most patients begin with non-surgical care, activity modification, weight management, physical therapy, anti-inflammatory medication, and in some cases joint injections. These measures can relieve symptoms and are often the right first step.
When hip arthritis is advanced and pain continues to limit your life despite these measures, hip replacement can relieve pain and restore function. It has been called “the operation of the century”.4 Dr. Harris tailors the timing and the surgical approach to each patient, using modern techniques rather than a one-size-fits-all plan.
The surfaces of the knee are covered in smooth cartilage that lets the joint bend and straighten without pain. Osteoarthritis, the most common form of knee arthritis, is the gradual wearing away of that cartilage. It often begins in one part of the knee before spreading, and as it thins, the smooth gliding surface is lost until bone rubs directly against bone.
Knee arthritis usually comes on slowly over months or years. Common signs include:
Knee osteoarthritis is driven by a mix of age, genetics, the alignment of the leg, and prior injury, such as a meniscus tear or ligament injury. Inflammatory types of arthritis, such as rheumatoid arthritis, are caused by inflammation of the joint lining rather than simple wear and can behave differently.
Most patients begin with non-surgical care, activity modification, weight management, physical therapy, anti-inflammatory medication, and in some cases joint injections. These measures can relieve symptoms and are often the right first step.
When knee arthritis is advanced and pain continues to limit your life despite these measures, knee replacement is one of the most effective treatments for advanced knee arthritis, relieving pain and restoring function for most patients.5 Depending on how much of the knee is involved, partial knee replacement is sometimes an option instead of a total, and modern and, where appropriate, robotic-assisted techniques are used to match the surgery to the knee. Which of these applies in any individual case is something to work through at a visit.
Post-traumatic arthritis is arthritis that develops after an injury to a joint. A fracture, dislocation, or a serious cartilage or ligament injury can damage the smooth joint surface or change the way the joint carries weight, causing the cartilage to wear out faster, sometimes years or even decades after the original injury. It can affect the hip or the knee.
The symptoms resemble other forms of arthritis, pain with activity, stiffness, swelling, and a gradual loss of motion, usually in a joint that was injured earlier in life.
Non-surgical care comes first. When the arthritis is advanced, hip or knee replacement relieves pain for most patients. A previous injury, or hardware such as plates and screws left from an earlier surgery, can make joint replacement more complex. Dr. Harris plans for that ahead of time, sometimes removing old hardware or correcting a deformity during the same operation.
Unlike the “wear-and-tear” of osteoarthritis, inflammatory arthritis, such as rheumatoid arthritis, is driven by the immune system attacking the lining of the joint. That inflammation gradually damages the cartilage and bone, and it often affects several joints at once.
Pain, swelling, warmth, and stiffness that is often worst in the morning. It is usually managed over time with a rheumatologist and medication.
When medication can no longer control the joint damage and pain, hip or knee replacement can relieve pain and restore function. Surgery timing and medications are coordinated with the patient’s rheumatologist to keep the operation and recovery as safe as possible.
In developmental dysplasia of the hip, the socket is shallow and doesn’t fully cover the ball of the hip, a difference in shape that is present from early life. The loose fit puts uneven stress on the cartilage, which can wear out early and lead to hip arthritis in younger adulthood.
Groin or hip pain that can begin earlier than typical arthritis, sometimes with a sense that the hip catches or gives way.
When dysplasia has led to advanced arthritis, hip replacement can relieve pain and restore function. A dysplastic hip has unusual anatomy that makes joint replacement more demanding, so Dr. Harris plans the reconstruction carefully from detailed imaging with the goal of a stable, well-aligned hip.
Femoroacetabular impingement happens when extra bone forms on the ball of the hip, the rim of the socket, or both, so the two surfaces pinch together during movement. Over time that pinching can damage the cartilage and the labrum, the ring of tissue that seals and cushions the socket, and contribute to hip arthritis.
Groin pain with deep bending, prolonged sitting, or pivoting, sometimes with stiffness or a catching sensation in the hip.
Earlier impingement is often managed without surgery. When it has progressed to advanced arthritis, hip replacement is a dependable way to relieve pain. Dr. Harris reviews imaging and symptoms with each patient and talks through the options at that stage.
Avascular necrosis (AVN), also called osteonecrosis, is the death of bone tissue caused by a loss of its blood supply. Bone is living tissue that depends on a steady flow of blood; when that flow is interrupted, an area of bone weakens and, over time, can collapse. When this happens near a joint, the smooth surface of the joint is damaged and arthritis follows. AVN most often affects the hip (the ball of the femur), but it can also involve the knee.
Sometimes no cause is found, but recognized risk factors include:
In its earliest stages AVN can be silent and is sometimes discovered on imaging done for another reason. As it progresses, it typically causes pain with weight-bearing, in the groin or hip, or in the knee, that steadily worsens. An MRI is the most sensitive test and can detect AVN before it is visible on an ordinary X-ray.
Treatment depends on how early the condition is caught and whether the bone has already collapsed. Caught early, before collapse, joint-preserving options may be considered. Dr. Harris reviews imaging and stage of disease with each patient at a visit.
Once the bone has collapsed and the joint surface is damaged, hip or knee replacement is usually the most dependable way to relieve pain and return to activity. Dr. Harris goes over where a patient is in the disease and what the options are at that point.
Modern hip and knee replacements are durable, and the great majority last for many years, often two decades or more.1,2,3 But no implant lasts forever, and occasionally a joint replacement can wear out or run into trouble sooner. When that happens, revision surgery can identify the problem and rebuild the joint.
New or worsening pain, swelling, a sense that the joint is giving way or clunking, decreased motion, or new difficulty bearing weight are all reasons to be evaluated. A joint replacement that becomes hot, red, and swollen, especially with a fever, needs same-day attention. Many of these problems are very treatable, especially when addressed early.
Revision surgery is more complex than a first-time joint replacement, and finding the cause is the essential first step. Dr. Harris evaluates the joint with a careful examination, X-rays, laboratory tests, and, when needed, advanced imaging.
The revision is then planned around the specific problem, exchanging worn or loose components, treating infection (sometimes in stages), restoring stability, or repairing bone. Part of Dr. Harris’s research looks at why joint replacements fail and how to make them last longer, and that work directly informs the care he provides to patients facing these problems.
This information is provided for general education and is not a substitute for a personal evaluation. Every patient is different; the right diagnosis and treatment plan can only be determined through an individual consultation.
General information for patients and clinicians, not a substitute for advice from your own surgeon.
These guides cover the common patterns, but your X-rays and your symptoms are what actually decide the plan. Send a message.
