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Study shows short-term efficacy of single injection of PRP for knee OA
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One injection with 10-times the normal concentration of leukocyte-free platelet-rich plasma is as effective as two injections of platelet-rich plasma for patients with knee osteoarthritis, according to results recently published in The American Journal of Sports Medicine.
“A single injection of white-blood-cell-filter platelet-rich plasma [PRP] in concentrations 10-times normal helps in early osteoarthritis and can be beneficial in well-selected patients,” study author Mandeep S. Dhillon, MS,FAMS, of the Post Graduate Institute of Medical Education and Research in Chandigarh, India, told Orthopedics Today.
The researchers compared the outcomes of three treatment groups:
- a single-injection group (26 patients);
- a group who received two injections of PRP 2 weeks apart (25 patients); and
- a placebo group injected with normal saline (23 patients).
The study consisted of 53 women and 22 men. The average patient age was 53 years. Inclusion criteria were patients with bilateral Ahlback’s grade 1 or 2 osteoarthritis. Dhillon and colleagues excluded patients who had recent interventions that could influence the effect of treatment or medical comorbidities. Patients were followed up at 6 weeks, 3 months and 6 months.
The placebo group showed no improvement in outcomes during the follow-up. The single- and double-injection groups showed similar improvements in WOMAC scores at early follow-up, but the results declined. “The effect lasted for a short period, 6 months,” Dhillon said. “However, the effects tended to taper off over time. We feel that there is a need for longer follow-up.”
The total WOMAC for the single-injection group decreased from 49.86 at baseline to 27.18 at final follow-up. Baseline scores for pain (10.18), stiffness (3.12) and physical function (36.56) also decreased at final follow-up (5.0, 2.10, and 20.8, respectively). In the double-injection group, the baseline WOMAC scores for pain (10.62), stiffness (3.5), physical function (39.10) and total score (53.20) changed to 6.18, 1.88, 22.4 and 30.48, respectively.
Complications
The researchers noted minor complications such as syncope, dizziness, headaches, sweating and tachycardia in six patients in the single-injection group and 11 patients in the double-injection group. The complications lasted a short time and did not affect treatment, outcome or discharge, Dhillon said. Some patients in the double-injection group experienced these complications only after the second injection. The researchers also found residual pain or stiffness for 48 hours in four patients in the single-injection group and three patients in the double-injection group.
“We have postulated that a higher platelet concentration in these cases may have been responsible for these adverse effects, but cannot prove this,” Dhillon said. “However, these adverse events were mild and uncommon and do not seem to influence the safety or efficacy of the procedure.”
The researchers noted the short follow-up, use of solely pain and stiffness for outcome measures and lack of radiographs or MRIs for assessment as study limitations.
“As one injection of leukocyte-free platelet-rich plasma seems to be as effective as two, it may be a good idea to give the staged injections after longer intervals, maybe a year or so, as the effect may then be potentiated longer, and maybe we could give a third one subsequently,” Dhillon said. “This is something we are working on at the present moment, and we would add radiological evaluations to [assess] for any documented changes after repeated platelet-rich plasma injections, since that would be an objective outcome evaluation.” – by Renee Blisard Buddle
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Disclosure: The study was funded by the Indian Arthroplasty Association and the Professor D. S. Grewal Memorial Orthopaedic Society.
Perspective
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Allan K. Mishra, MD
I was privileged to hear Dr. Mandeep Dhillon present his paper, "Treatment with Platelet-Rich Plasma (PRP) is more effective than placebo for knee osteoarthritis" last year at a biologic orthopedic meeting in Mumbai, India. I was intrigued by the level 1 evidence from the study supporting the use of a single PRP treatment for patients with knee arthritis. Specifically, the investigation noted significant pain reduction and functional improvements in PRP-treated patients compared to a placebo control group at 6 months. Importantly, the authors provided a detailed description of the type of PRP used in the study allowing for potential replication (type 4 PRP: concentrated platelets with white blood cell reduction and calcium chloride activation). Transient nausea and dizziness were reported by between 22% and 44% of the PRP patients. The authors suggested calcium chloride activation may have been a contributing factor to these side effects. It will be important to see if similar clinical results could be obtained if the platelet activation step were eliminated. It may be not be needed because the abundant collagen within the connective tissue of the knee joint should act as an in-vivo PRP activator.
When listening to Dr. Dhillon in India, I was reminded of the global nature of medical information. We need to embrace the challenge of trying to identify and digest the exploding volume and diversity of data. Finally, the authors should be congratulated on their substantial contribution to the medical literature on how to best use emerging autologous biologic technologies such as PRP.
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