The most common reason people need a hip replacement is osteoarthritis, a condition where the cartilage lining the hip joint gradually wears away until bone grinds against bone. But osteoarthritis isn’t the only path to a hip replacement. Inflammatory diseases, loss of blood supply to the bone, traumatic injuries, and structural problems present from birth can all damage the hip severely enough to require surgery.
Osteoarthritis and Cartilage Breakdown
Osteoarthritis accounts for the vast majority of hip replacements. The process starts when the cells responsible for maintaining cartilage become overactive and begin breaking down the smooth, rubbery tissue that cushions the joint. The cartilage surface develops tiny cracks and starts to fray. Over time, the protective matrix erodes further, the tissue calcifies, and blood vessels from the underlying bone begin pushing into areas they shouldn’t be.
What makes this so consequential is that once the collagen network in cartilage is degraded, it cannot be repaired to its original state. The body simply doesn’t have the machinery to rebuild that specific structure. As the cartilage thins and disappears, the ball of the femur and the socket of the pelvis lose their buffer. The result is bone-on-bone contact, which produces deep, persistent pain, stiffness, and progressive loss of mobility. At that point, no amount of rest or medication can restore what’s been lost.
Inflammatory Arthritis
Rheumatoid arthritis and other inflammatory conditions attack the hip from a different angle. Instead of slow mechanical wear, the immune system triggers chronic inflammation inside the joint lining. The tissue that normally produces lubricating fluid becomes swollen and overgrown. Specialized immune cells, including large multinucleated cells, begin actively breaking down bone and cartilage from within. Biopsies of affected joints show abundant fibrin deposits, fibrosis, and fragments of bone being consumed by inflammatory cells.
This process can be faster and more destructive than osteoarthritis. Some patients experience what’s called rapidly destructive inflammatory arthritis, where the joint deteriorates significantly within months rather than years. Because the damage is driven by the immune system rather than wear and tear, it can affect people at younger ages and may involve both hips simultaneously.
Avascular Necrosis: When Bone Loses Its Blood Supply
The head of the femur depends on a specific set of blood vessels to stay alive. When that blood supply is disrupted, bone cells die and the femoral head gradually collapses. This condition, called avascular necrosis or osteonecrosis, is one of the leading reasons younger adults end up needing a hip replacement.
Traumatic causes are the most straightforward. A femoral neck fracture or hip dislocation can physically damage the blood vessels feeding the bone. Decompression injuries from scuba diving (known as Caisson disease) create nitrogen bubbles that block small arteries supplying the bone.
Nontraumatic causes are more varied and sometimes surprising. Long-term corticosteroid use is one of the most common culprits. Excess steroids appear to alter circulating fats in the blood, creating tiny blockages in the arteries that feed bone tissue. Heavy alcohol use carries a similar risk. Sickle cell disease is particularly damaging: the misshapen red blood cells directly obstruct blood flow, and roughly 50% of patients with sickle cell disease develop osteonecrosis by age 35. Gaucher disease, a hereditary metabolic disorder, causes osteonecrosis in up to 60% of affected patients. Other associated risk factors include lupus, chronic kidney failure, organ transplantation, pancreatitis, and HIV.
Hip Injuries and Post-Traumatic Arthritis
A serious hip or pelvis injury can set the stage for arthritis years or even decades later. Fractures that extend into the acetabulum (the hip socket) are especially problematic because even small irregularities in the joint surface create abnormal wear patterns. Research on patients with transverse acetabular fractures found that fractures involving the posterior wall of the socket roughly doubled the risk of developing post-traumatic osteoarthritis. Femoral head damage and residual fracture lines similarly increased the risk by about twofold.
Hip dislocations compound the problem. Beyond damaging the cartilage surface directly, they can injure the blood supply to the femoral head, adding the risk of avascular necrosis on top of the mechanical damage. Even with surgical repair, the joint may never track as smoothly as it did before the injury.
Developmental Hip Dysplasia
Some people are born with a hip socket that is too shallow, unstable, or improperly formed. This spectrum of conditions, called developmental dysplasia of the hip (DDH), ranges from mild looseness to complete dislocation at birth. Even when treated early with bracing, some patients retain enough residual abnormality that the joint wears out prematurely.
The numbers are striking. Approximately 25 to 50% of patients with hip dysplasia develop visible osteoarthritis on X-rays by age 50. If hip instability was present at birth, the relative risk of eventually needing a hip replacement is 2.6 times higher than normal. In Denmark, DDH accounts for 21 to 29% of all hip replacements performed in young adults, making it the single most common reason people under 50 need the surgery. Late diagnosis, past three months of age, increases the likelihood that surgical intervention will eventually be necessary.
When Replacement Becomes the Right Option
Hip replacement is an elective procedure, meaning it’s scheduled rather than performed as an emergency. The decision centers on two things: pain that disrupts daily life, and failure of nonsurgical treatments to provide adequate relief.
Before surgery is considered, guidelines from the American Academy of Orthopaedic Surgeons recommend a structured course of conservative management. Anti-inflammatory medications (NSAIDs) have the strongest evidence for reducing pain and improving function. Physical therapy is recommended for mild to moderate cases. Corticosteroid injections into the joint can provide short-term relief. Notably, hyaluronic acid injections, sometimes marketed as joint lubrication shots, are explicitly recommended against for hip osteoarthritis because they perform no better than placebo. Opioids are also discouraged for managing hip arthritis pain.
When these approaches stop working and pain begins limiting basic activities like walking, climbing stairs, or sleeping, replacement surgery enters the conversation. There’s no single lab test or imaging finding that triggers the decision. It’s ultimately about how much the hip is affecting your quality of life and whether you’ve reached a point where the functional limitations outweigh the risks of surgery.
Age Trends and Implant Longevity
Hip replacement was originally designed for elderly, low-demand patients. That profile has shifted considerably. The surgery is increasingly performed in younger patients who tend to be more active and have higher expectations for what they’ll be able to do afterward. Studies of patients under 55 report a mean age in the mid-to-late 40s, with some patients as young as 19.
Youth does introduce specific concerns. Higher activity levels and longer remaining lifespans mean more cumulative stress on the implant. Younger patients face greater risk of bearing surface wear and component loosening over time, which may eventually require a second (revision) surgery. That said, implant technology has improved substantially. Long-term survival analysis of modern ceramic-on-ceramic hip implants shows a 93% survival rate at 25 years, meaning the vast majority of implants are still functioning well after a quarter century. For most patients, a hip replacement done today has a strong chance of lasting the rest of their lives.