Dr Low specialises in administering PRP injections for the treatment of knee osteoarthritis.

What are PRP injections?

Platelet-rich plasma (PRP) injections are a relatively new treatment for osteoarthritis (articular cartilage damage) of the knee. The procedure involves injecting the platelet-rich plasma component of the patients own blood into their knee joint. Platelets are a type of blood cell that are involved in the healing and scar tissue formation of damaged cartilage. They are full of growth factors and cytokines which play a crucial role in joint homeostasis (lubrication and nutrition) and healing.


Benefits of PRP injections

At present there is nothing that can restore damaged articular cartilage to its original state. PRP injections have good evidence to help reduce pain and improve function in patients with knee osteoarthritis, as well as slowing down the progression of osteoarthritis. This can enable people to exercise again and avoid using harmful NSAID anti-inflammatories on a regular basis. Its effects for pain relief can last up to 12 months and sometimes even longer. Patients can have repeat injections at regular intervals. Because your own blood is used, there is no risk of transmissible disease or reaction to a foreign body.


When to use PRP injections?

They are used to improve symptoms in patients with knee osteoarthritis and slow the progression of the knee osteoarthritis. They can be used in patients whose osteoarthritis is not severe enough to warrant a knee replacement. They are also used to manage symptoms in patients who wish to continue exercising with mild and moderate osteoarthritis. PRP injections have been used in patients of a large age frame, including patients as young as 21 with early knee osteoarthritis and as old as 85 with moderate knee osteoarthritis.


When NOT to use PRP injections

Absolute contraindications to PRP injections (absolute reasons not to have)

  • Platelet dysfunction syndrome

  • Critical thrombocytopaenia

  • Hypofibrinogenemia

  • Hemodynamic instability

  • Septicaemia

  • Systemic cancer

  • Chemotherapy

  • Steroid therapy

  • Blood disorders and platelet abnormalities

  • Anticoagulation therapy ie. Warfarin


Relative contraindications to PRP injections (possible reasons not to have)

  • Consistent use of anti-inflammatories within 1 week of procedure

  • Steroid injection at treatment site or systemic use within last 2 weeks

  • Recent fever or illness

  • Rash at site

  • Active history of Pseudomonas, Enterococcus or Klebsiella infection

  • Haemoglobin <10g/dl

  • Platelet count <105/uL

  • Chronic liver disease

  • Hepatitis

  • Chronic infection


Before the procedure

Avoid for 72 hours before injection

  • Aspirin

  • Any Anti-inflammatories such as Nurofen, Voltaren, Mobic, Celebrex, Naproxen

  • St John’s Wort, Garlic

  • Vigorous exercise or physical work that may exacerbate your knee symptoms. Try and minimize any physical work if you have a physical job.


Avoid for 2 weeks before injection

  • Vitamin E, Fish oil supplements


The procedure

The whole procedure takes about 40 minutes. Its important to be well hydrated for ease of taking blood. Dr Low or a nurse will take 2 tubes of blood from you. This will be spun in a centrifuge machine which separates the different components of the blood. The plasma component is then injected into the painful knee joint. For best results patients have 3 injections over a 1 month period with 2 weeks in between injections.


After the procedure

The knee can feel a bit “full” after the injection. You can drive home or back to work after the injection, however it is advised to get someone else to drive you home if you have to travel for an hour or more. You should avoid strenuous activity for 2-3 days.

Patients may experience discomfort for approximately 24 hours after the injection. Simple analgesia such as Panadol, and elevating the leg can help alleviate these symptoms. Anti-inflammatory medications should be avoided for 48 hours after the injection so as not to inhibit any healing cascade put into effect by the platelets.

To give the PRP injections the best chance of improving symptoms, beginning or continuing a knee muscle rehabilitation program with a physio, exercise physiologist or an experienced personal trainer is crucial to giving you the best results. Some patients look to the PRP injections as a quick fix. However to get the best results some rehab work done by the patient also needs to be done. Dr Low can refer you to the appropriate health professional if needed.




Program for pain relief and knee rehabilitation during and after PRP injections


For knee Osteoarthritis 3 injections are given in total with 2 weeks in between injections (ie. 3 injections in 28 days)


Day 1 and 2
Pain Relief

  • Avoid ice and cold laser therapy

  • Use Panadol or Panadeine for pain relief

  • Avoid Anti-inflammatories and steroids


  • Rest and avoid loading the joint where PRP was administered (sit for most of day)

  • Gentle bending and straightening of knee non-weight bearing

  • Office job fine to continue

  • Physical job advise against for 1st 48 hours


Days 3 to 7

Pain relief

  • Use Panadol, Panadeine or Anti-inflammatories

  • Ice

Rehab (ideally through a physio or exercise physiologist)

  • Gentle bending and straightening of knee weight bearing

  • Gentle loading of the joint

  • > exercise bike, Quads+pelvic+core activation

  • > single leg raises, clams etc ie. not loading joint too much

Days 8 to 14

Pain relief

  • Ice, Panadol, Panadeine, Anti-inflammatories as needed


  • Normal Osteoarthritis knee rehab concentrating on knee muscle strengthening, activation and balance

  • Active/passive range of motion with joint loaded

  • Commence squats, lunges etc.


This program then needs to recommence after both the 2nd and 3rd PRP injections. Rehab should continue for more than 14 days after the 3rd PRP injection. The time period for this rehab with depend on response to rehab and the PRP injections.


The PRP injections can improve symptoms as early as 7 days after the first injection, but it may take up to 6 weeks after the 3rd injection. For best results from the PRP injections, a knee rehab program performed at the same time is essential.


PRP injections can be repeated in the future if knee symptoms worsen again. These can be performed anytime 6 months after the previous PRP injections.




Efficacy of platelet-rich plasma injections in osteoarthritis of the knee: a systematic review and meta-analysis.

Laudy ABM, Bakker EWP, Rekers M, et al.

BR J Sports Med 2015;49:657-672.

A randomized clinical trial evaluating plasma rich in growth factors (PRGF-Endoret) versus hyaluronic acid in the short-term treatment of symptomatic knee osteoarthritis. 

Sánchez M, Fiz N, Azofra J, et al. 

Arthroscopy 2012;28:1070–8.

Platelet-rich plasma intra-articular injection versus hyaluronic acid viscosupplementation as treatments for cartilage pathology: from early degeneration to osteoarthritis. 

Kon E, Mandelbaum B, Buda R, et al. 

Arthroscopy 2011;27:1490–501.