Reference: Am J Sports Med. 2019 Nov;47(13):3238-3246 (level 1 [likely reliable] evidence)
Chronic plantar fasciitis is a common foot complaint in the United States. Up to 15% of these complaints fail non-operative conservative therapy among adults (Foot Ankle Int. 2014). In acute cases, plantar fasciitis is characterized by classic signs of inflammation, including pain, swelling, and loss of function. For more chronic cases, however, inflammation is not the underlying etiology of ongoing symptoms. In fact, histology of chronic cases in one study showed no signs of inflammatory cell invasion into the affected area (J Am Podiatr Med Assoc. 2003). Numerous methods have been advocated for treating plantar fasciitis, including corticosteroid injections (Foot Ankle Int.2014, Am Fam Physician. 2005 Dec 1). However, due to the pathophysiology of the disease, could platelet-rich plasma (PRP) therapy be more beneficial? The study to be reviewed offers evidence to answer this question.
A recent double-blind randomized controlled trial compared the efficacy of PRP injection to triamcinolone acetonide 40 mg/mL injection (control) in 115 adults (mean age 49 years, 71% women) with chronic plantar fasciitis (≥ 6 months) refractory to non-operative treatment (Am J Sports Med. 2019). All patients had a bupivacaine injection as a local field block prior to randomized injection, and were kept in a seated position without moving the foot for 15 minutes immediately following injection. The primary outcome was the Foot Function Index (FFI) Pain score with successful treatment defined as a score reduction of 25% between baseline and 12-month follow-up. Secondary outcomes included FFI Activity and Disability scores, American Orthopedic Foot & Ankle Society Score, and the World Health Organization Quality of Life (WHOQOL-BREF) score (short version of the WHOQOL-100). All outcomes were measured at baseline and 4, 12, 26 and 52 weeks after injection. At baseline, patients in the PRP group had FFI scores 6-10 points higher than patients in the triamcinolone group, although no p values were reported. 71.3% of patients completed the study and were included in the analysis.
Compared to control at 12 months (after adjusting for baseline differences), PRP was associated with reduced pain (mean difference 14.4 points, 95% CI 3.24-25.57) and disability (mean difference 11.97 points, 95% CI 2.29-21.64), with greater rate of successful treatment (84.4% with PRP vs. 55.6% with control [p = 0.003]). There were no significant differences in quality of life (WHOQOL-BREF) at 12 months.
Based on the results of this study, patients who received PRP injections had significant improvement of their plantar fasciitis pain and disability scores lasting over 12 months when compared to corticosteroid injections.
Strengths of the study include computer-based randomization, both groups received the same imaging studies per study protocol, and all patients followed the same procedure during and after injections to help maintain blinding.
One major limitation of the study was its high loss to follow up at 12 months (17 patients in the PRP group [27%] and 16 patients in the cortisone group [31%]). For those patients, the last available measurement was used to determine treatment success. In using the last available measurement, the true degree of success of the therapy at 12 months cannot truly be determined with such a high degree of drop out.
Another problematic element was the significant baseline difference in duration of symptoms between the study and control group. The duration of symptoms in the PRP group had a median duration of symptoms of 70 weeks (40-130) compared to control 52 weeks (35-90). Also, different doses of PRP were used at different centers, though there appears to be no difference in using different PRP concentration kits on overall results. Another concern is the inclusion of 8 patients who did not meet inclusion criteria as this could affect the overall results. Finally, this trial did not use ultrasound guided injections which could lead to inconsistent dose delivery during joint injection.
While this study shows promising results for the efficacy of PRP therapy, more research is needed to overcome the limitations of this study and further assess the role of PRP for plantar fasciitis.
For more information, see the Plantar Fasciitis topic in DynaMed.
Abdulrahman Baqais, MD attended King Abdulaziz University Faculty of Medicine and Allied Sciences in Jeddah, Saudi Arabia and is a Board Certified Family Medicine Physician, who graduated from HCA-Memorial Family Medicine Residency Program in Savannah, GA. He is currently a sports medicine fellow at HCA-Memorial Sports Medicine Fellowship Program in Savannah, GA. He desires to practice sports medicine when he completes his fellowship, caring for patient/athletes of all ages.
Faculty contributions by Dr. Marvin Sineath