Revision Hip and Knee Replacement:
When a Prior Implant Fails

Why joint replacements are not permanent

A well-performed primary total hip or knee replacement is one of the most reliably successful procedures in medicine, and most implants function well for 15–25 years or longer. But every implant is a mechanical device sitting inside a biological environment, and over time several things can go wrong: the bond between implant and bone can loosen, the polyethylene bearing surface can wear, the joint can become unstable or dislocate, the bone around the implant can fracture, or bacteria can colonise the implant surface and cause a low-grade or acute infection.

Revision arthroplasty is the term for the operation that addresses any of these problems — removing some or all of the original components and replacing them, sometimes with specialised implants designed specifically for a compromised bony bed. It is a fundamentally different operation from a first-time replacement: the surgeon is usually working through scar tissue, with less native bone stock, and with an existing implant that has to be removed cleanly before anything new can be put in.

What causes an implant to fail

The relative importance of different failure causes has shifted over the past two decades. Improvements in bearing surfaces and fixation techniques have reduced wear-related and aseptic loosening failures, while infection has become a relatively larger share of the problem — partly a true increase, and partly because aseptic causes have declined faster.

Cause	What's happening	Typical timing
Aseptic loosening	The bond between implant and bone weakens, often related to wear debris or years of mechanical load	Usually later — years to decades after surgery
Periprosthetic joint infection	Bacteria colonise the implant surface, either introduced at the time of surgery or seeded later via the bloodstream	Can be early (weeks–months) or late (years) after surgery
Instability / dislocation	The joint repeatedly dislocates or feels unstable, often related to component position or soft-tissue laxity	Most common in the first 1–2 years
Periprosthetic fracture	A fracture of the bone around the implant, usually after a fall or other trauma	Any time after surgery
Wear / osteolysis	Wear particles from the bearing surface trigger bone loss around the implant	Typically later, related to cumulative use

Recognising a failing implant

The symptoms of a failing hip or knee replacement overlap with ordinary post-surgical aches, which is exactly why they are easy to dismiss for too long. A joint that was comfortable for years and then gradually or suddenly becomes painful again deserves attention, particularly when the pain has different qualities than the original arthritis pain.

Any of the infection-related signs — warmth, redness, drainage, fever — should prompt urgent rather than routine evaluation, since periprosthetic joint infection generally responds better to treatment the earlier it is identified and confirmed.

How implant failure is diagnosed

Work-up starts with plain X-rays to look for loosening, wear, osteolysis (bone loss around the implant), component malposition, or fracture, usually compared against earlier post-operative films to detect gradual change. Blood tests — inflammatory markers such as CRP and ESR — help screen for infection, though they are not specific on their own. When infection is suspected, joint aspiration (removing fluid from around the implant for analysis and culture) is typically the most important single test, since it can identify the causative organism and guide antibiotic selection. CT or advanced imaging is sometimes used to characterise bone loss more precisely before planning surgery. Distinguishing infection from aseptic loosening matters enormously, because the surgical strategy — and the number of operations required — differs substantially between the two.

How revision surgery differs from a first-time replacement

For aseptic failure — loosening, wear, instability, or fracture without infection — revision is often possible as a single operation: the failed components are removed and new ones, sometimes with longer stems or augments to make up for bone loss, are implanted in the same surgery.

Infection is handled differently. The two most established strategies are:

One-stage (single-stage) revision: the infected implant is removed and a new implant is placed in the same operation, combined with thorough debridement and a course of targeted antibiotics. This approach is increasingly used in carefully selected patients with a known, treatable organism and good soft tissue quality.

Two-stage revision: the infected implant is removed and replaced temporarily with an antibiotic-loaded spacer, followed by a course of intravenous antibiotics, and then a second operation weeks to months later to implant the definitive new components once the infection is confirmed to be cleared. This remains the more established approach for many periprosthetic joint infections, particularly with more resistant organisms or more extensive infection.

Outcomes: what revision surgery can and cannot promise

Revision arthroplasty relieves pain and restores function for most patients, but outcomes are, on average, less predictable than for a first-time replacement — operative time is typically longer, recovery is slower, and the complication profile is higher, largely because the surgeon is working with compromised bone and soft tissue rather than a native joint. Outcomes also depend heavily on how many prior revisions a joint has already had: patients undergoing a repeat revision generally fare worse than those having their first revision.

Because of this, revision arthroplasty is increasingly concentrated at high-volume centres with dedicated revision teams, specialised implant systems, and access to infectious disease specialists — a pattern reflected in how referral networks for revision surgery are typically structured.

A growing part of orthopaedic practice

As the number of primary hip and knee replacements performed worldwide continues to rise, and as patients live longer with their implants, the overall volume of revision surgery is projected to grow substantially in the coming decades. US Medicare projections estimate that revision total knee arthroplasty volume could increase by roughly 149% by 2040 and over 500% by 2060 relative to a 2019 baseline, with revision total hip arthroplasty also projected to grow, though more modestly (Shichman et al., Arthroplasty Today, 2023). This growth is one of the reasons dedicated revision arthroplasty services have expanded as a distinct area of specialisation within orthopaedic surgery, separate from primary joint replacement practice.

If you have a hip or knee replacement and are experiencing new pain, instability, or any signs suggestive of infection, the appropriate first step is a clinical evaluation with updated X-rays and, if infection is a concern, blood tests and possibly joint aspiration — rather than assuming the discomfort will pass on its own or waiting to see if it worsens.