A painful knee that has already been replaced needs a different assessment from arthritis in a natural knee. Before considering PRP, the priority is to understand the implant, surrounding tissues and the cause of the change. Research about injections for knee osteoarthritis does not automatically apply to pain after a knee replacement. A clear orthopaedic review is more useful than choosing an injection from the symptom alone. [1-3]
Why the replacement changes the question
A total knee replacement replaces joint surfaces with artificial components. Pain afterwards can have several explanations, including implant loosening or wear, instability, stiffness and infection. AAOS describes these as reasons that some patients need further treatment or revision surgery. That does not mean every painful replacement needs another operation. It means the cause needs to be established before a treatment is offered. [1]
Tell the clinician whether the knee never became comfortable after surgery or whether it worked well and has recently changed. A new problem after a good period of function is useful information. So are swelling, a feeling that the knee gives way, a fall, changes in movement and any problem with the wound. Bring the date and hospital of the original operation, the surgeon's letters and any recent imaging.
The practical first question is not "Can I have PRP?" It is "What is causing pain in this replaced knee, and who should assess it?"
When not to wait for an injection consultation
Redness or swelling around a knee replacement, wound drainage, or increased pain or stiffness in a previously well-functioning joint need prompt medical attention. Infection can occur months or years after surgery, and the absence of a fever does not safely exclude it. Contact your operating team or seek urgent medical assessment rather than waiting for an elective PRP appointment. [2]
A fall followed by a major change in pain or function also needs assessment. AAOS describes fractures around a replacement as a separate complication that may require surgical care. Do not assume a new injury is an ordinary arthritis flare. [1]
These warnings are not a diagnosis. They are reasons to use the right route early. A clinic enquiry form is not a substitute for urgent care when the knee has changed substantially or you feel acutely unwell.
What an orthopaedic review may involve
The review begins with the history, an examination and the previous operation details. The clinician may use X-rays to assess the components and the surrounding bone. If infection is suspected, blood tests and sometimes sampling fluid from the joint may be considered. The choice and interpretation of tests belong to the treating team, not a generic injection checklist. [1,2]
Blood tests such as ESR and CRP measure inflammation and are not, on their own, a complete explanation of a painful replacement. AAOS describes further joint-fluid testing where appropriate. A test result should be interpreted with the examination and the clinical picture. [2]
Bring a medicines list and details of any recent treatments. Ask what each proposed investigation is intended to answer, how the result would change care and who will discuss it with you. If another clinician is taking over the review, sharing the original surgical and follow-up records can help avoid an incomplete picture.
Review The London PRP Clinic's assessment and treatment services. If you already have a replacement, say so when enquiring so that the appropriate assessment route can be discussed before any procedure is booked.
Why osteoarthritis PRP claims do not settle this decision
PRP is prepared from a person's blood and injected into a selected tissue. Its evidence varies by condition. AAOS discusses PRP for conditions including knee arthritis and tendon problems, but that general overview does not establish a treatment benefit for unexplained pain in an artificial knee. [3]
An artificial implant that is loose, unstable or infected poses a different problem from osteoarthritis in a natural joint. PRP should not be sold as a way to repair an implant, replace an infection assessment or avoid revision surgery without first establishing what is wrong. The existence of a PRP service does not make every knee-pain enquiry an injection candidate.
If an injection is proposed, ask which structure is being treated, how the diagnosis was made, what evidence applies to your particular situation and whether your arthroplasty team should be involved. A discussion about a tendon outside the joint is also not the same as evidence for injecting a replaced joint. The anatomical target and the clinical question must be clear.
How to prepare for a private review in London
A useful enquiry includes the operation date, which knee was replaced, the main change in symptoms and whether you are already under the care of the operating team. Have the operation report, recent X-rays or scan reports and any relevant blood results ready if available. You do not need to purchase a new scan simply to make an enquiry.
Before agreeing to an appointment, confirm the clinician's role, what the review includes and whether further tests or specialist input would be charged separately. Ask how findings will be communicated to your existing team. There is no fixed recovery promise or automatic injection course that can be given from the words "pain after knee replacement".
Explore the clinic's services before arranging the next step. The aim is a diagnosis-led plan, with a specialist route where needed, rather than a procedure chosen before the cause is known.
Sources and evidence limits
- AAOS: Revision Total Knee Replacement. Causes of replacement failure and assessment pathways.
- AAOS: Infection After Joint Replacement. Symptoms and investigation of possible implant infection.
- AAOS: Platelet-Rich Plasma. General PRP overview, not proof of benefit for a painful knee replacement.
This article is general information, not an individual diagnosis or a recommendation to inject a replaced joint.