Revision Total Knee Replacement

Why this approach — at MOS

Revision knee replacement rewards preparation above all else. We obtain a full history of the original implant — manufacturer, component sizes, fixation method, and operative notes if available — before planning. Knowing what was implanted helps us anticipate the extraction challenge and select compatible or appropriately sized revision components.

The failure mode diagnosis is not negotiable. We do not take a patient to revision surgery for unexplained pain without aspiration and serology. The revision rate for misdiagnosed infection that was treated as mechanical failure is very high, and the patient's outcomes in that scenario are poor. When infection is the cause, we use a two-stage protocol, which has superior infection eradication rates compared to single-stage revision for most organisms.

We maintain a comprehensive revision inventory including constrained condylar, rotating platform, and rotating hinge systems. For bone defects, we use trabecular metal cones and sleeves for larger defects rather than exclusively relying on cement filling — the long-term fixation data for porous metal augments in load-bearing defects is favorable. Patients from across Montgomery County who present with complex revision scenarios benefit from coordinated pre-operative planning and access to our full implant inventory.

Our post-operative protocol mirrors the principles of primary replacement but with appropriate caution: weight-bearing is advanced more gradually when bone stock is compromised, and physical therapy is tailored to the constraint level of the implant used.

Who is a candidate?

Indications

• Aseptic loosening: The most common cause of late failure — the implant gradually loses fixation to the bone, causing pain with weight-bearing and identifiable bone loss on X-ray
• Periprosthetic joint infection (PJI): Bacterial infection around the implant — the most feared complication, requiring staged removal and reimplantation
• Polyethylene (plastic) insert wear: The plastic spacer thins over time, eventually allowing metal-on-metal contact; exchanging only the plastic insert (isolated polyethylene exchange) may be sufficient in early cases
• Instability: The knee feels loose or gives way due to collateral ligament insufficiency, flexion-extension gap mismatch, or tibial component rotation mismatch
• Stiffness / arthrofibrosis: Severe restriction in range of motion (less than 90° flexion) that does not respond to physical therapy or manipulation under anesthesia
• Periprosthetic fracture: Fracture around the femoral or tibial component that cannot be fixed without revision of the implant
• Implant fracture: Failure of the metal components themselves (rare with modern alloys)
• Persistent pain: When all other causes of post-replacement pain have been systematically excluded

Contraindications

• Active soft tissue infection overlying the knee without adequate wound management first
• Extensor mechanism disruption (patellar tendon or quadriceps tendon rupture) requiring staged repair
• Medically unstable patient unable to tolerate prolonged surgery
• Insufficient bone stock to achieve stable fixation without vascularized bone grafting (rare; requires tertiary-level planning)
• Unclear diagnosis — revision surgery for persistent pain without a confirmed mechanical or infectious cause has high failure rates and should not be undertaken without thorough investigation

Conservative Treatment First

Revision knee replacement is not a procedure that has a non-surgical alternative in the classic sense — once an implant has failed for a confirmed mechanical reason, the implant must be addressed. However, the conservative element in revision surgery lies in thorough pre-operative evaluation: ruling out infection, confirming the diagnosis of failure mode, optimizing medical comorbidities, and considering whether less extensive interventions (isolated polyethylene exchange, manipulation under anesthesia for stiffness) can address the problem before committing to full revision surgery.

Not every patient with knee pain after replacement needs revision. Persistent pain without mechanical failure should prompt evaluation for referred pain from the hip or spine, complex regional pain syndrome, or unrecognized infection — all treatable without revision surgery. The principle of "confirm the diagnosis before operating" is particularly important in revision surgery, where the risks of intervention are substantially higher than in primary replacement.

The procedure

What Is Revision Total Knee Replacement?

Revision total knee replacement is surgery to remove and replace all or part of a failing knee replacement implant. It is performed when a prior replacement wears out, loosens, becomes infected, or causes persistent pain or instability. The procedure takes 90 to 150 minutes at a hospital and is substantially more complex than a primary replacement.

Most primary total knee replacements are durable for 15–20 years or longer. But implants are mechanical devices, and like all mechanical devices, they can fail over time. The challenge of revision surgery is not simply removing one implant and inserting another. When an implant loosens or fails, bone loss occurs — sometimes significant bone loss — and the surrounding soft tissues (ligaments, extensor mechanism) may be compromised. The revision surgeon must work around these deficits, using specialized implant systems with stems, augments, and higher levels of constraint to achieve stable fixation in diminished bone stock.

Revision knee replacement is one of the most technically demanding procedures in orthopedic surgery. The outcomes depend heavily on correct identification of the failure mode — infection versus mechanical failure — because the treatment is fundamentally different. Periprosthetic joint infection (PJI) requires a staged protocol with implant removal, antibiotic spacer placement, and reimplantation after infection eradication. Mechanical failure (loosening, wear, instability, stiffness) is addressed with single-stage revision if infection has been excluded.

The stakes are higher than for primary replacement. Revision patients have longer surgeries, more blood loss, higher complication rates, and longer recoveries than primary replacement patients. Meticulous pre-operative planning and the availability of a comprehensive implant inventory — including constrained, rotating platform, and hinged designs — are prerequisites for consistently good results.

What Happens During Revision Total Knee Replacement?

Pre-operative Evaluation

Revision surgery begins weeks before the operating room. Every patient with a painful or failing knee replacement undergoes a structured diagnostic evaluation: weight-bearing X-rays, nuclear medicine bone scan or metal artifact reduction sequence (MARS) MRI, blood tests for infection markers (CRP, ESR, serum D-dimer), and crucially, aspiration (needle withdrawal) of joint fluid for culture and synovial white cell count. The distinction between infection and mechanical failure must be made before surgery — a mistake here can be catastrophic.

Anesthesia and Positioning

Revision procedures are performed under general or spinal anesthesia at the hospital. The patient is positioned supine. A tourniquet is applied; however, in revisions with significant bone loss or complex anatomy, the tourniquet is used selectively to avoid masking vascular anatomy.

Exposure

The previous surgical incision is used when possible to avoid creating areas of skin between two incisions that could lose blood supply ("skin bridges"). Exposure is typically more challenging than in primary surgery due to scarring and adhesions. The quadriceps mechanism is mobilized carefully.

Implant Removal

The original components are removed using specialized extraction instruments that minimize bone damage. This is a critical step — aggressive extraction can create or worsen bone defects. Cement removal is performed meticulously using osteotomes, ultrasonic tools, and high-speed burrs.

Bone Loss Assessment and Defect Management

After implant removal, bone defects are classified and addressed:

• Small cavitary defects — filled with bone graft or cement
• Moderate peripheral defects — addressed with metal augment blocks attached to the revision implant
• Large structural defects — may require structural allograft bone, trabecular metal cones or sleeves, or in extreme cases, a segmental replacement

Implant Selection and Fixation

Revision implants have several key features not found in primary implants: intramedullary stems that extend into the femoral and tibial canals to bypass compromised metaphyseal bone, metal augments to fill peripheral defects, and higher levels of constraint to compensate for compromised ligaments. Fully constrained rotating hinge designs are used when collateral ligament function is absent. Cemented or hybrid fixation (cementless stems with cemented metaphyseal components) is chosen based on bone quality.

Two-Stage Protocol for Infection

When periprosthetic infection is confirmed, single-stage revision is generally not performed. Stage 1 removes all implant components and cement, debrides infected tissue, and places an antibiotic-eluting cement spacer. The patient receives 6 weeks of intravenous antibiotics guided by the organism identified in culture. Stage 2 reimplants new components after infection markers return to normal and repeat aspiration confirms eradication of infection.

Closure

Wound closure requires more attention in revision cases because soft tissue quality is often reduced from prior surgery. Drains may be placed. The closure is inspected carefully before dressing application.

Recovery timeline

Frequently Asked Questions