After evaluating this article, participants will be able to:
1. Incorporate into practice the knowledge to discuss PRP with patients who request this treatment
2. Understand the limitations of PRP
3. Incorporate into clinical practice new strategies for muscle and tendon injuries
Is platelet-rich plasma a viable treatment option for muscle and tendon injuries?
While on a recent shift in the ED, I was asked a familiar question by a weekend warrior who had suffered an ankle sprain while playing basketball - “What can I do to get back on the court sooner, Doc?” After explaining the usual RICE protocol (Rest, Ice, Compression, Elevation) my persistent patient asked “What else can I do? What about these platelet rich plasma (“PRP”) injections I hear about?”
This was the third time in the past month that I was asked about this new therapy in the management of muscle and tendon injuries, and so I decided to put on my Columbo hat and do some investigation on PRP (being caught off guard on the court or within the ED is not something I am fond of). After some initial research on Google followed by Pub MED, the bottom line for emergency physicians is this: if you haven’t been asked about PRP, get ready. The question is coming. A growing number of professional athletes, including three-time baseball MVP Alex Rodriguez, two-time Super Bowl MVP Hines Ward, CY Young winner Cliff Lee and golf superstar Tiger Woods have brought the treatment front and center, contributing to its awareness and popularity across active patient populations. Additionally, an increasing number of clinical studies are surfacing with greater regularity, many extolling the virtues of the once controversial protocol. This has led to expanded usage in the medical community.
What is Platelet Rich Plasma (PRP)?
A bioactive component of whole blood, PRP has a higher concentration of platelets in comparison to baseline blood. These platelets contain granules that can release numerous growth factors such as platelet derived growth factor (PDGF), insulin like growth factor-1 (IGF-1), fibroblastic growth factor (FGF), VEGF (vascular endothelial growth factor), EGF (epidermal growth factor) and hepatocyte growth factor (HGF) that have a key role in the healing of injured tissue. The presence of multiple growth factors in physiological proportions in PRP makes it a positive clinical choice when compared to treatments using isolated growth factors.
PRP is obtained by withdrawing blood from a vein in the patient’s arm and then placing it in a centrifuge to separate the different blood cell types. The physician then extracts the platelet rich portion of the blood, which is then injected directly into the area of injury to create a medium for cell growth and differentiation to facilitate repair and recovery of the injured tissue. Because PRP is derived from the patient’s own blood, the risk of rejection/adverse reaction is highly unlikely. Additionally, because the treatment takes place in one visit, it is less costly than other therapies that require a sorting or culturing period before clinical use.
PRP and Tendon Injuries
Given the fact that PRP contains a variety of growth factors that influence the three phases of tendon healing – inflammation, proliferation, and remodeling, it is a logical choice to assist in the initiation and/or acceleration of recovery from tendon-related injuries and conditions.
Mishra and Pavelko conducted the first in vivo human investigation of PRP for the treatment of chronic elbow tendinosis. All patients in the prospective cohort study had failed nonoperative treatment and were considering surgical options. Four weeks after treatment, the PRP group reported a mean 46% improvement in their visual analog pain scores compared to a 17% improvement in the control group. At eight weeks post treatment the PRP group escalated to a 60% improvement while the control group remained relatively the same at 16%. At six months, the PRP group had improved to 81% over baseline and a final follow up at a mean 25.6 months saw PRP-treated patients report a 93% reduction in pain with 93% categorizing their experience with the treatment as “completely satisfied” and “essentially pain free”. Overall, patients reported engaging in 99% of daily activities and 94% of their work or sporting activities from one injection with no reported complications.
A recent randomized control trial by Gosens et al. published in the American Journal of Sports Medicine (2011) compared the effectiveness of PRP against corticosteroid injections in 100 patients with chronic lateral epicondylitis. Primary analysis included visual analog scale (VAS) pain scores and disabilities of the arm, shoulder and hand (DASH) outcome scores. At 2 year follow up, the PRP and corticosteroid groups both significantly improved across time (intention-to-treat principle). However, the DASH scores of the PRP group significantly improved (as-treated principle) in comparison to the corticosteroid group (who returned to baseline levels). PRP was thus shown to reduce pain and increase function well above the effect of the steroid injection at 2 year follow up.
PRP and Muscle Injuries
Muscle injury (strains/contusions) occurs from either acute or repetitive trauma resulting in a decreased ability to produce force even after a short period of rest. These injuries are amongst the more common complaints treated by physicians. Standard therapy has involved RICE protocols and there has been no clear consensus on treatment of muscle injuries beyond these otherwise conservative protocols.
Similar to the three phases of tendon healing, muscle healing is influenced by growth factors as well. Hammond et al. investigated the effect of PRP on muscle healing in what they described, to their knowledge, as “the first study to use PRP in a model of muscle strain injury.” Using an animal model of contraction induced injury to more closely approximate normal physiology; researchers determined that PRP can hasten recovery from muscle strain injuries noting that delivery of growth factors to the site of injury may be a useful suggestion beyond RICE protocols. They also offered further clarification of the types of muscle injuries that might be best served by PRP and the mechanism of recovery. “Local delivery of platelet-rich plasma can shorten recovery time after a muscle strain injury…recovery of muscle from high-repetition protocol has already been shown to require myogenesis, whereas recovery from single strain does not. This difference in mechanism of recovery may explain why platelet-rich plasma was more effective in the high-repetition protocol because platelet-rich plasma is rich in growth factors that stimulate myogenesis.”
Not a Panacea
As promising as PRP is in the treatment of tendon and muscle injury, further study is needed – specifically, double blind placebo controlled randomized control trials with strong methodological rigor and larger numbers of patients – to determine the essential qualities of the treatment and most effective way that it can be used. Even with paucity of well conducted clinical studies, researchers recognize that the current body of knowledge on PRP “points to a future in which platelet-rich therapies will continue improving existing conventional approaches to treatment of sports injuries.” A consensus paper from the International Olympic Committee published in 2010 in the British Medical Journal recommends to “proceed with caution in the use of PRP” as more research is necessary to determine its efficacy or otherwise.
One additional caveat to convey to patients who participate in competitive sports and wishing to explore PRP is that they should check with the governing bodies of their respective sport to ensure that the treatment is allowed under their rules and regulations. This is even good advice on the high school and collegiate level as well. While it does not appear to be problematic at this point in time (PRP is permitted by all routes of administration by the World Anti-Doping Agency), other anti-doping agencies have yet to be definitive in their opinion on the topic. However, it should be noted that PRP is not blood doping, which is forbidden in most sports. Blood doping occurs when an athlete has blood removed and only injects the drawn blood back into the body after normal levels have been restored after a more significant passage of time has passed, unlike the immediate re-injection of platelet rich blood seen with PRP. The result with blood doping is a boost in oxygen-rich blood and potential performance.
While further studies with greater scientific rigor are necessary to determine the optimal use of PRP in healing various types of injuries commonly seen in the emergency setting, the existing and growing body of clinical evidence is promising as a potential step beyond RICE. Given the apparent safety and reported efficacy of the protocol, PRP may be the next frontier in the non-surgical treatment of commonly seen muscle and tendon injuries and being an informed provider about the details of this new therapy will allow for enhanced communication to our patients at the time of disposition planning and to avoid being “caught off guard”.
STEP 3: TAKE THE QUIZ
STEP 4: PROCESS PAYMENT
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