Knee replacement is one of the most successful operations in medicine, but it does not work perfectly for everyone. A small percentage of patients experience ongoing pain, stiffness, instability, or other problems that prevent them from achieving the relief they expected. When a knee replacement fails to meet expectations, the question is why.
Dr. Leo Zalikha evaluates problematic knee replacements with a systematic approach honed during his adult reconstruction fellowship at Stanford Medicine. The goal is to identify the specific cause of failure and determine whether revision surgery, conservative management, or further workup is the right next step.
Limited range of motion is one of the more common problems after knee replacement. If you cannot bend your knee past 90 degrees or cannot fully straighten it despite diligent physical therapy, the cause may be scar tissue formation (arthrofibrosis), component sizing or positioning issues, or other factors that a revision specialist can evaluate.
A knee that feels wobbly, gives way during walking, or does not feel trustworthy may have ligament insufficiency or component imbalance. Some patients describe it as feeling like the knee is "not tight enough" or "not mine."
Persistent or recurring swelling months after surgery can indicate infection, wear debris, or a soft tissue problem. Acute new swelling without an obvious cause is particularly concerning.
Catching, clicking, clunking, or a sense that something is "catching" inside the knee can indicate component loosening, polyethylene wear, or impingement.
A gradual decline in what you can do, shorter walking distances, more difficulty with stairs, reluctance to leave the house, is a signal that something is not right.
Prosthetic joint infection can present as obvious (acute swelling, warmth, fever) or subtle (chronic low-grade pain, intermittent swelling). It is one of the first diagnoses Dr. Zalikha rules out when evaluating a painful knee replacement, because the treatment is completely different from other causes of failure.
The implant can lose its bond with bone over time, particularly if wear particles trigger an inflammatory response. Loosening causes pain with weight-bearing, often with a progressive component.
Imbalanced soft tissues or undersized components can leave the knee unstable in flexion, extension, or both. This is a correctable problem, but it usually requires revision surgery to address.
Excessive scar tissue formation can restrict motion despite appropriate rehabilitation. Treatment options range from manipulation under anesthesia to surgical lysis of adhesions to formal revision.
A knee replacement that is poorly aligned, malrotated, or improperly sized can cause pain, limited motion, and accelerated wear. This is one reason Dr. Zalikha uses robotic-assisted technology for primary knee replacement: to reduce the chance of malposition that leads to failure.
Pain in the front of the knee after replacement can result from patellar tracking issues, patellar component loosening, overstuffing of the patellofemoral joint, or residual articular damage.
Not all pain around a replaced knee comes from the implant itself. Hip arthritis, lumbar spine disease, vascular claudication, and complex regional pain syndrome can all cause knee-area pain. A careful evaluation that looks beyond the knee is critical.
When did the problems start? Was there ever a pain-free period after surgery? What activities are limited? Has there been any injury, illness, or dental procedure that preceded the symptoms?
Assessment of range of motion, stability (in multiple planes and through the arc of motion), gait, patellar tracking, and signs of infection. The hip and spine are also examined to rule out referred pain.
Standing X-rays (AP, lateral, and merchant views) are compared to any available prior films. A CT scan with metal artifact reduction protocol may be ordered to evaluate component rotation, sizing, and bone integrity.
Blood tests for ESR and CRP, and joint aspiration with fluid analysis (cell count, differential, cultures, and potentially molecular testing). Ruling out infection is non-negotiable before proceeding with any revision plan.
The original operative report, implant records, and post-operative course provide valuable information about what was done and what may have gone wrong.
The path forward depends on the diagnosis:
Treatment follows specific protocols, which may include debridement with implant retention (DAIR) or staged revision with antibiotic spacer placement, as outlined on the prosthetic joint infection page.
Revision knee replacement with appropriate components to address the specific problem
Manipulation under anesthesia, lysis of adhesions, or revision depending on the cause
Treatment directed at the actual source (spine, hip, vascular, or pain management)
Continued observation, therapy, or further specialized testing
Dr. Zalikha is honest about what revision surgery can and cannot fix. If the cause of pain is unclear or if revision surgery is unlikely to improve the situation, he will say so.
If your knee replacement is not performing as expected, Schedule a consultation with Dr. Zalikha or call (562) 362-5024. A Virtual Second Opinion is available for patients outside the area.
