Current Insights On PRP And Achilles Tendinopathy

As platelet-rich plasma (PRP) continues to gain more use in healthcare, can it effectively treat Achilles tendinopathy? This author assesses the viability of PRP in the Achilles, drawing on the literature and his own clinical experience with the modality.

Platelet rich plasma (PRP) has been a hot topic in the medical field in recent years. It is part of a new field, sometimes referred to as regenerative medicine. The theory behind this approach is to take a sample of autologous blood, centrifuge the blood (thereby creating a concentrate of platelets), and then extract and administer this platelet concentrate to the diseased structure. Growth factors can assist in the healing of tendons, ligaments and other connective tissues in the body so the theory is that a concentrate of the platelets administered directly to the diseased or injured tissues will help facilitate repair.

The potential ability to biologically stimulate a vast array of musculoskeletal conditions in this manner is compelling at the very least. The media is full of descriptions of professional athletes treated with PRP and getting miraculous cures for conditions that otherwise only had surgical solutions in the past. I have found even surgical patients who have also had PRP treatment may have accelerated recoveries in comparison to more traditional approaches.

Does PRP work? Does this sound too good to be true? We still do not have conclusive answers to these questions. Clearly, this approach has both its advocates and skeptics. There are thousands of articles addressing this question. Many of these are case studies or those lacking peer review. It probably doesn’t help that you now see PRP mentioned in the context of hair transplants, non-surgical facelifts and a myriad of other applications. Panacea solutions in medicine generally meet with some degree of skepticism. On the other hand, PRP is still advertised as a treatment option in many esteemed academic health science centers, most typically in the sports medicine departments.

Like many, my interest in PRP started as a curiosity more than 10 years ago. My primary interest was Achilles tendinopathy, not so much for insertional disease but the more dreaded hypovascular mid-tendon region. I believe this condition has always been a difficult one to treat, especially in the younger and middle-aged, more active individuals. Conservative care measures have had limited results in the past, and the condition is progressive and ultimately results in tendon rupture.¹

The more common surgical approaches for Achilles tendinopathy have been either tendon debridement or augmentation by flexor hallucis longus tendon transfer. Both surgical approaches have provided reasonable successes but with some pitfalls. For me, tendon transfer has not produced predictable returns with higher end activities and debridement was risky when substantial tendon disease was present. It also seemed that any option that would repair a tendon prior to rupture might offer a patient a less complex recovery than what exists with an end-to-end Achilles tendon repair. As a result, a new option that would expand treatment alternatives was welcome.

What The Author’s Study Revealed About PRP Efficacy

Through the years, I have used many commercially available PRP kits. I never envisioned doing a study so there was no consistency as to the selection process. Early on, I mostly judged my patient successes with this approach by the simple question as to whether patients felt better or not after treatment. Many did improve. As time progressed, so did the parameters by which I used PRP. I had always obtained pre-procedure magnetic resonance imaging (MRI) in order to gauge the extent of tendon disease and over time, I began to obtain post-procedure MRIs several months or later after treatment. It was clearly important that the patient feel better but did the tendon disease actually improve or reverse on MRI?

The results of my experience with PRP were interesting and as a result, a study was born.² Our study focused on 26 patients, half of whom had Achilles tendon surgery in combination with PRP administration and the other half of whom had PRP alone. In our patient population, all patients had to fail at least six months of conservative care before receiving PRP. All patients had to have a pre-injection MRI to confirm and quantify the extent of tendinopathy. All patients had to have had a MRI at least one year post-treatment to establish whether the tendon showed improvement or not, and the extent of that improvement. All study patients must have had platelet retrieval by the same commercial PRP system. All patients had to complete a functional scoring system via the Victorian Institute of Sports Assessment-Achilles (VISA-A) questionnaire.³

One of the difficulties was grading the MRI as to the severity of the tendinopathy in order to compare pre- and post-treatment studies.² Since we could not find any grading system, we had to create one. A radiologist graded each MRI without knowledge as to which patient he or she was reviewing. We also had been treating Achilles tendinopathy with PRP by two means: injection alone or in combination with tendon debridement. We thought it might be of interest to compare these two groups. We then statistically compared the groups.

We found successes in both study groups.² There was, as one would expect, a linear relationship in those patients with improved functional scoring and in those whose post-procedure MRIs were markedly improved post-injection. More simply stated, tendons that appear healthier on MRI seem to have better functional outcomes.

Caveats Regarding The Study Results

It is always good to have some critical constructive review and I would offer some on our study.² Had I envisioned that I would eventually do a study when I first started using PRP, I might have considered a prospective study versus a retrospective study. I would have considered a control group although withholding promising treatment in the interests of science in clinical practice is never an easy undertaking. So in a perfect world, these would have been better choices. I also would have used only one or two commercial platelet retrieval kits because you need consistency when doing studies in order to compare outcomes between groups more effectively. As a result, our patient numbers for inclusion in the study suffered.

On the positive side, I felt the study was able to confirm our clinical impressions that PRP does work but it does not work in every case. I believe the no-harm, no-foul factor with PRP administration to be a plus. Surgery is still there for those patients who do not get better. The other interesting observation looking back is that there were patients I thought would for sure get better and did not. There were also patients who had such extreme cases of tendinopathy that I thought as a result of the severity and the extent and pervasiveness of tendon disease, that they would not get better but they did.

What The Studies Reveal

There is one more factor that I think may be important. When we did our literature review, we found an interesting observation in those studies that used PRP by injection alone. Some studies recommended immobilization after injection and some did not.

In one of the hallmark studies, de Vos and colleagues claimed PRP did not work but they did not immobilize patients after the injection.⁴ The randomized study included 54 patients with chronic tendinopathy who received either a PRP injection or a saline injection. In the PRP group, the validated VISA-A scores, measuring pain and activity level, improved after 24 weeks by a mean 21.7 points in comparison to a mean 20.5 point improvement in the placebo group. Unfortunately, this study has become the basis for insurance company denials of payment.

Similarly, a recent randomized controlled trial by Krogh and colleagues focused on 24 patients with chronic Achilles tendinopathy who received either PRP or saline.⁵ During a three-month follow-up, the authors note the VISA-A score did not improve in patients treated with PRP.

Guelfi and colleagues studied the use of a single PRP injection in 73 patients (83 tendons) with non-insertional mid-portion chronic recalcitrant Achilles tendinopathies.⁶ The authors note that the patients’ mean baseline VISA-A scores of 45 improved to 88 postoperatively. More than 91 percent of patients rated their treatment as satisfactory and would repeat the treatment. Researchers also reported no Achilles tendon ruptures.

However, in a study of 44 patients with non-insertional Achilles tendinopathy, Salini and colleagues found the effects of PRP were less effective in older people (with a mean age of 61.5 years in the study).⁷
How do patients fare in the long term after PRP injection? Filardo and coworkers studied 27 patients (34 tendons) with chronic mid-portion Achilles tendinopathy.8 Authors note patients’ VISA-A scores showed significant improvement at six months and stable results at 4.5 years.

What often goes unmentioned is that there are many studies showing improvement when immobilization was part of the post-PRP injection treatment protocols. Dean and coworkers conducted a prospective case series of 26 patients (two bilateral cases) with painful Achilles tendinopathy (confirmed by ultrasound) for a minimum of six months.⁸ Treatment consisted of an intratendinous autologous-conditioned plasma injection followed by a standardized rehabilitation protocol, which included full weightbearing in a pneumatic cast boot for six weeks. The authors related statistically significant improvements in terms of pain, activities of daily living, sports activities and quality of life.

I think there is logic here because one of the principles advocated with PRP injections is that you fenestrate or make multiple passes with the needle through the diseased tendon, thereby converting the chronic wound into a more acute wound, which would help stimulate repair. As a result, we elected to immobilize all our patients in walking boots post-injection for a few weeks.

In Conclusion

The era of biological solutions is upon us. It offers potential degrees of sophistication we have yet to experience and many doors to unlock to make such technologies more uniformly successful. Since starting to use PRP, I find myself with more questions than answers. There are many growth factors and all we are able to do at this time is administer their platelet source. Attempts to isolate specific growth factors for specific clinical applications are not there yet.

We do not know if it makes a difference if higher platelet concentrations ultimately offer more successful clinical outcomes. Is this a one injection treatment or multiple injections? How long can patients experience success?

Another limiting factor has been insurance company reimbursement. In my experience, most insurance companies do not pay for this technology so the burden of the costs falls on the patient. Similarly, the burden of out of pocket expenses for medical care has been increasingly falling on our patients as a natural consequence of the high deductible insurance plans that most patients have these days.

As PRP and other biologic therapies become further refined, I believe they will become preferred treatment alternatives. Recovery from an injection is clearly of less risk and shorter recovery than a surgical procedure. Hopefully, further research will pave the way with the answers that make this potential treatment option more universally successful and acceptable.

Dr. Oloff is in private practice at Sports Orthopedic and Rehabilitation Medicine Associates in Redwood City, Calif. He is the Team Podiatrist for the San Francisco Giants.

References

1.     Andres BM, Murrell GA. Treatment of tendinopathy: what works, what does not, and what is on the horizon. Clin Orthop Relat Res. 2008; 466(7):1539–1554.
2.     Oloff LM, Elmi E, Nelson J, Crain J. Retrospective analysis of the effectiveness of platelet-rich plasma in the treatment of Achilles tendinopathy: pretreatment and posttreatment correlation of magnetic resonance imaging and clinical assessment. Foot Ankle Spec. 2015;8(6):490-7.
3.     Robinson JM, Cook JL, Purdam C, Visentini PJ, et al. The VISA-A questionnaire: a valid and reliable index of the clinical severity of Achilles tendinopathy. Br J Sports Med. 2001;35(5):335-41.
4.     De Vos RJ, Weir A, van Schie HT, et al. Platelet-rich plasma injection for chronic Achilles tendinopathy: a randomized controlled trial. J Am Med Assoc. 2010 13;303(2):144-9.
5.     Krogh TP, Ellingsen T, Christensen R, et al. Ultrasound-guided injection therapy of Achilles tendinopathy with platelet-rich plasma plasma or saline: a randomized, blinded, placebo-controlled trial. Am J Sports Med. 2016; 44(8):1990–7.
6.     Guelfi M, Pantalone A, Vanni D, et al. Long-term beneficial effects of platelet-rich plasma for non-insertional Achilles tendinopathy. Foot Ankle Surg. 2015; 21(3):178–81.
7.     Salini V, Vanni D, Pantalone A, Abate M. Platelet rich plasma therapy in non-insertional Achilles tendinopathy: the effect is reduced in 60-years-old people compared to young and middle-aged individuals. Front Aging Neurosci. 2015; epub Dec. 10.
8.     Deans VM, Miller A, Ramos J. A prospective series of patients with chronic Achilles tendinopathy treated with autologous-conditioned plasma injections combined with exercise and therapeutic ultrasonography. J Foot Ankle Surg. 2012; 51:(6):706-710.