Understanding what is causing your hip or knee pain is the first step toward feeling better. Below are explanations of the conditions Dr. Harris treats most often, and how he approaches each one. Select a topic to read more.

Hip Arthritis (Osteoarthritis)

What it is

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.

What it feels like

Hip arthritis usually comes on slowly over months or years. Common signs include:

  • A deep, aching pain most often felt in the groin, and sometimes in the buttock or the front of the thigh
  • Pain that is worse with walking or standing and eases with rest
  • Stiffness getting in and out of a car, or putting on shoes and socks
  • A limp, or the sense that the leg is becoming shorter or harder to rotate
  • Pain that begins to interfere with sleep and daily life

Why it happens

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.

How Dr. Harris can help

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 is one of the most reliable operations in medicine for relieving pain and restoring function. Dr. Harris tailors the timing and the surgical approach to each patient, using modern techniques rather than a one-size-fits-all plan.

Knee Arthritis (Osteoarthritis)

What it is

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.

What it feels like

Knee arthritis usually comes on slowly over months or years. Common signs include:

  • An aching pain along the joint line that is worse with activity and eases with rest
  • Pain going up or down stairs, kneeling, or squatting
  • Stiffness after sitting for a while, along with swelling, grinding, or catching
  • A sense that the knee may buckle or give way
  • A gradual bow-legged or knock-kneed change in the shape of the leg over time

Why it happens

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.

How Dr. Harris can help

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 reliable operations in medicine for relieving pain and restoring function. Depending on how much of the knee is involved, Dr. Harris may recommend partial rather than total knee replacement, and uses modern and, where appropriate, robotic-assisted techniques to match the surgery to your knee.

Post-Traumatic Arthritis

What it is

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.

What it feels like

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.

How Dr. Harris can help

Non-surgical care comes first. When the arthritis is advanced, hip or knee replacement reliably relieves pain. A previous injury, or hardware such as plates and screws left from an earlier surgery, can make replacement more complex. Dr. Harris plans for that ahead of time, sometimes removing old hardware or correcting a deformity during the same operation.

Inflammatory (Rheumatoid) Arthritis

What it is

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.

What it feels like

Pain, swelling, warmth, and stiffness that is often worst in the morning. It is usually managed over time with a rheumatologist and medication.

How Dr. Harris can help

When medication can no longer control the joint damage and pain, hip or knee replacement can relieve pain and restore function. Dr. Harris coordinates closely with your rheumatologist around the timing of surgery and your medications to keep the operation and recovery as safe as possible.

Developmental Dysplasia of the Hip (DDH)

What it is

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.

What it feels like

Groin or hip pain that can begin earlier than typical arthritis, sometimes with a sense that the hip catches or gives way.

How Dr. Harris can help

When dysplasia has led to advanced arthritis, hip replacement can relieve pain and restore function. A dysplastic hip has unusual anatomy that makes replacement more demanding, so Dr. Harris plans the reconstruction carefully from detailed imaging to rebuild a stable, well-aligned hip.

Femoroacetabular Impingement (FAI)

What it is

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.

What it feels like

Groin pain with deep bending, prolonged sitting, or pivoting, sometimes with stiffness or a catching sensation in the hip.

How Dr. Harris can help

Earlier impingement is often managed without surgery. When it has progressed to advanced arthritis, hip replacement is a dependable way to relieve pain, and Dr. Harris will review your imaging and symptoms to recommend the right step for where you are.

Avascular Necrosis (Osteonecrosis)

What it is

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.

What causes it

Sometimes no cause is found, but recognized risk factors include:

  • Long-term use of corticosteroid medication
  • Significant alcohol use
  • A prior hip fracture or dislocation that disrupted blood flow
  • Certain medical conditions, such as sickle cell disease and lupus

What it feels like

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.

How Dr. Harris can help

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, and Dr. Harris will review your imaging and stage of disease with you.

Once the bone has collapsed and the joint surface is damaged, hip or knee replacement is the most dependable way to relieve pain and return you to activity. Dr. Harris will help you understand where you are in the disease and recommend the approach best suited to your situation.

When a Hip or Knee Replacement Fails

Modern hip and knee replacements are durable, and the great majority last for many years, often two decades or more. But no implant lasts forever, and occasionally a replacement can wear out or run into trouble sooner. When that happens, revision surgery can identify the problem and rebuild the joint.

Why a replacement can fail

  • Aseptic loosening. The implant gradually loses its bond with the bone without infection being present. In the hip this often involves the socket (acetabular cup) or the stem in the femur; in the knee, the femoral or tibial component. It typically shows up as pain with weight bearing and a change in the position of the implant on X-ray.
  • Bearing surface wear and osteolysis. The plastic (polyethylene) liner in a hip socket or the plastic insert in a knee wears over time. The resulting particles can trigger the body to resorb bone around the implant, a process called osteolysis, which loosens the components.
  • Periprosthetic joint infection (PJI). Bacteria settle on the implant surface and form a biofilm. Early infections, within weeks of surgery, are sometimes treated by washing out the joint and exchanging the plastic liner, while later, established infections usually require exchanging the implants, often in two stages with an antibiotic spacer in between.
  • Periprosthetic fracture. A break in the bone around the implant, usually after a fall or in bone weakened by osteoporosis. Around a hip replacement this is most often a fracture of the femur near the stem; around a knee replacement it can involve the femur just above the implant, the tibia below it, or the patella (kneecap).
  • Instability or dislocation. In a hip replacement, the ball can slip out of the socket, most often when the implants sit in a position that does not match the patient’s anatomy or when the surrounding muscles are weak. In a knee replacement, instability feels like buckling or giving way, usually from ligament imbalance or loosening of the plastic insert.
  • Stiffness (arthrofibrosis). After a knee replacement, dense scar tissue can form inside the joint and limit bending and straightening. When early stiffness does not improve with therapy, a manipulation under anesthesia can restore motion; established arthrofibrosis sometimes requires surgery to remove the scar tissue, occasionally with a revision.
  • Extensor mechanism problems. In the knee, the quadriceps or patellar tendon can rupture, or the patellar component can loosen or wear, making it difficult to straighten or hold the leg out against gravity.
  • Implant fracture or component failure. Uncommon, but a stem, a modular junction, or a plastic insert can crack or break, generally in the setting of high stress or long-standing wear.
  • Adverse reaction to metal debris. Wear at a metal-on-metal or a modular metal junction can release metal particles that irritate the surrounding soft tissue, causing pain, fluid collections, and, over time, tissue damage.
  • Persistent unexplained pain. Occasionally a replacement hurts without an obvious cause. Careful evaluation is essential here, both to identify a treatable problem and to avoid an operation that would not help.

Signs to watch for

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. Many of these problems are very treatable, especially when addressed early.

How Dr. Harris can help

Revision surgery is more complex than a first-time 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. Much of Dr. Harris’s research is devoted to understanding why 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.

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