Platelet-Rich Plasma Treatment for the Lumbar Spine: A Review and Discussion of Existing Gaps

Background: Platelet-rich plasma (PRP) is obtained by centrifuging autologous whole blood to extract a layer concentrated with platelets, growth factors found in platelet granules, and cytokines. These components work together to promote and facilitate the healing process at sites of injury. An increasing number of clinical studies are assessing the efficacy of PRP as a treatment for lower back pain. Objectives: Lumbar back pain is a significant cause of years lived with disability. This paper conducts a thorough review of clinical studies on intradiscal, facet-joint, epidural, and mixed-target PRP interventions in the lumbar spine. Furthermore, gaps in the current literature regarding lumbar spinal PRP injections are identified to help guide future clinical trials. Study Design: Literature review. Methods: An initial search was conducted using Ovid MEDLINE, focusing on PRP injections in the spine. Boolean operators were used to combine MeSH terms and key words such as "spine," "lumbar spine," "thoracic spine," "cervical spine," "intervertebral disc," "platelet-rich plasma," and "inject." The search revealed an absence of papers about PRP injections into the cervical and thoracic spine, so the review was written with a specific focus on the lumbar spine. For the purposes of this paper, the selected manuscripts were separated into categories of intradiscal, facet-joint, epidural, and mixed-target PRP injections. Results: A multitude of case reports, case series, prospective clinical studies, and randomized controlled trials have yielded results supporting the use of intradiscal, facet-joint, and epidural PRP injections in the lumbar spine. However, a handful of papers suggest that PRP lacks efficacy in improving lumbar back pain and function. With the relative dearth of literature assessing the effects of spinal PRP injections, additional double-blinded randomized trials are needed. Important findings from available studies include the observation of PRP's increased efficacy over time, the correlation of the number of targeted injection sites with the efficacy of PRP injections, and the correlation of platelet count with PRP injections' efficacy.Limitations: There exists wide variability in PRP preparation protocols and in the methods of assessing PRP's therapeutic benefits between each study that evaluates PRP's effects in the lumbar spine. Conclusions: All clinical studies evaluating PRP as a form of treatment for the lumbar spine should include full transparency and details about the methods used for PRP preparation and injection. Future double-blinded randomized trials can fill in existing gaps by assessing the effects of platelet concentration and dose on the extent of clinical improvement as well as by establishing an expected timeline for clinical improvement after PRP injections. Cross-study standardization of which pain scoring systems to utilize for study evaluation would increase comparability among different papers.