Rock, paper, scissors: Resolving the conflicting results of randomized trials involving corticosteroid, platelet rich plasma (PRP) and placebo injections

Abstract

Objective

To explore whether there is evidence of a rock-paper-scissors phenomenon in injections for various musculoskeletal conditions whereby platelet rich plasma (PRP) injections outperform corticosteroid injections (CSI) in randomized trials, corticosteroid outperforms placebo whereas PRP does not outperform placebo.

Methods

Narrative review searching for examples of musculoskeletal conditions which have high level evidence of this proposed rock-paper-scissors phenomenon.

Results

High quality studies or reviews could be found for lateral epicondylitis (tennis elbow), knee osteoarthritis, rotator cuff tendinopathy and plantar fasciitis suggestive of a rock-paper-scissors phenomenon. This was consistently in the direction of PRP injections having superior results to corticosteroid injections, corticosteroid injections having superior results to placebo, but then evidence that PRP injections were not superior to placebo. The most consistent result of the triumvirate was that PRP injections consistently outperformed corticosteroid injections in the medium-term (4 to 12 months).

Discussion

There appears to be somewhat of a rock-paper-scissors phenomenon for four common musculoskeletal conditions, with the significant limitation that this was a finding of a narrative review, limited by a non-systematic search protocol. The underlying explanation is that PRP is superior to corticosteroid in the medium-term (but not the short-term), corticosteroid is superior to placebo in the short-term (only) with PRP not being superior to placebo in either short- or medium-term in well-blinded trials. The most likely explanation for this phenomenon is that corticosteroid injections are helpful for musculoskeletal conditions in the short term (≤8 weeks) but are actually harmful in the medium-term (3 months and beyond). Systematic reviews which further explore this phenomenon are justified to help provide practical evidence-based advice on when to, if ever, use PRP and corticosteroid injections for musculoskeletal conditions.