Symptomatic knee osteoarthritis
The evidence is most consistent for mild or moderate knee osteoarthritis when therapeutic exercise, load management and other non-surgical options have not adequately controlled the symptoms.
Non-surgical orthopaedic treatment
Intra-articular injections and PRP
An injection is a selective option incorporated into a treatment plan once the diagnosis has been established. PRP is used mainly to help control symptoms in mild or moderate knee osteoarthritis in carefully selected patients.
Clinical principle
PRP does not mean “new cartilage” and does not replace a diagnosis.
PRP—platelet-rich plasma—is obtained from the patient's own blood by separating and concentrating a platelet-rich fraction. It does not contain stem cells and should not be presented as a treatment that reverses osteoarthritis.
The realistic goal is to reduce pain and improve function for a variable period, allowing the patient to continue therapeutic exercise and activities appropriate to their condition.
Selecting the clinical indication
Where PRP may fit into treatment
Other joints
For the hip, shoulder or ankle, the evidence is less consistent. The precise location of the pain, the diagnosis and the quality of evidence for the particular condition should be discussed before the procedure.
Inflammation and joint effusion
A swollen joint or a large effusion may require clarification of the cause and, sometimes, joint aspiration or tests before an injectable product is selected. Infection must be excluded when the clinical picture raises suspicion.
The procedure
Steps in a PRP injection
Consultation and diagnosis are the first steps.
The protocol is tailored to the joint, the stage of the condition, previous treatments and the patient's medical profile.
Assessment
Symptoms, clinical examination findings and investigations are assessed together to confirm the source of the pain and the severity of joint damage.
Blood collection
A sample of venous blood is collected under sterile conditions, much like a routine blood draw.
Preparation
The blood is centrifuged to separate the plasma fraction that will be used. PRP products prepared by different systems do not all have the same composition.
Injection and follow-up
The product is injected into the joint, with imaging guidance when the anatomy or the joint makes this necessary. Aftercare advice and reassessment are individualised.
Choosing the product
Comparing injectable options
PRP
PRP is an autologous product derived from the patient's own blood. In mild or moderate knee osteoarthritis, it may reduce pain and improve function in selected patients, although the magnitude and duration of benefit vary.
Other injections
A corticosteroid may provide short-term relief in certain situations. Guideline recommendations differ for hyaluronic acid. These products are not equivalent and should not be repeated automatically without reassessment.
Safety
What to discuss before and after the procedure
Tell your doctor if you have a fever, an active infection, a skin lesion near the injection site or a blood disorder, or if you take anticoagulant or antiplatelet medication. Do not stop any treatment on your own initiative.
A temporary painful or inflammatory reaction may occur after the injection. Fever, spreading redness, marked local warmth, pronounced swelling or persistent worsening of pain requires prompt medical assessment.
Further information
Frequently asked questions about PRP
Does PRP regenerate cartilage?
PRP should not be presented as a method that is guaranteed to rebuild cartilage. In selected patients, it may reduce symptoms and improve function, but the response varies and the osteoarthritis does not disappear.
Who may be suitable for PRP?
The evidence is most consistent for mild or moderate symptomatic knee osteoarthritis. PRP is considered after the diagnosis has been confirmed and previous non-surgical treatments have been reviewed.
How many injections are needed?
There is no single protocol suitable for everyone. The number of injections and the interval between them depend on the product used, the confirmed diagnosis, the severity of the condition and the clinical response.
Does PRP work immediately?
When an effect occurs, it is usually gradual. Pain may temporarily increase after the procedure, and the outcome cannot be guaranteed or properly assessed after only a few days.
Is PRP also appropriate for the hip, shoulder or ankle?
PRP has also been studied in other joints, but the evidence is less consistent than for knee osteoarthritis. An indication established for the knee should not be automatically extended to every painful joint.
Appointment
A sound clinical indication is more important than the product injected.
The consultation determines whether an injection has a realistic goal, which option may be considered and how it fits into a complete rehabilitation and follow-up plan.
Medical emergency?
In an acute or life-threatening situation, call 112 or go to the nearest emergency department.