Platelet-rich plasma for chronic tennis elbow: letters to the editor

Platelet-rich Plasma or Autologous Blood Do Not Reduce Pain or Improve Function in Patients with Lateral Epicondylitis: A Randomized Controlled Trial

BACKGROUND

Platelet-rich plasma (PRP) and autologous blood are commonly used therapies for lateral epicondylitis, but the evidence from randomized, placebo-controlled trials is conflicting. Thus, it is still unclear if patients benefit from these treatments.

QUESTIONS/PURPOSES

In the setting of a randomized, placebo-controlled trial, we compared PRP, autologous blood, and saline injections in the treatment of lateral epicondylitis with respect to: (1) VAS pain scores, and (2) functional outcomes (DASH score and grip strength) 1 year after treatment.

METHODS

We performed a parallel-group, randomized, controlled participant- and assessor-blinded study including adults with clinically diagnosed lateral epicondylitis. We defined lateral epicondylitis as pain in the lateral humeral epicondyle area exacerbated during resisted wrist extension and epicondyle compression. The participants were recruited from a secondary referral center, after not responding to initial nonoperative treatment. Patients with other concomitant upper-limb symptoms and surgical treatment of the elbow were excluded. Randomization sequence was generated with computer software and concealed from the investigators. We randomized 119 participants to receive an injection of PRP, autologous blood, or saline (1:1:1) in the proximal insertion of the extensor carpi radialis brevis muscle; 40 participants received PRP, 40 received autologous blood, and 39 received a saline injection. To prepare the PRP, we collected venous blood with a syringe kit followed by centrifugation, whereas autologous blood group received unprepared blood injection. Two unblinded investigators gave injections while the participant was unable to see the injection. There was no formal postinjection rehabilitation protocol and the use of NSAIDs was similar between different treatment arms. Follow-up visits were at 4, 8, 12, 26, and 52 weeks after the injection. The primary outcome measure was improvement in pain, measured with VAS scale (without specification as to whether the pain was activity related or at rest; range 0-10; a higher score indicates worse pain; the minimum clinically important difference [MCID] on the 10-cm scale was 1.5 cm), from baseline to 52 weeks. The secondary outcomes were the DASH score (range 0-100; a higher indicates a poorer outcome, and the MCID was 10.2 points) and grip strength. All patients were included in the analyses, and analyses were performed using the intention-to-treat principle. There was no crossover between treatment groups. At 52 weeks, nearly all (95% [38 of 40]) participants in autologous blood group were available for analysis whereas 78% (31 of 40) and 82% (32 of 39) were available in PRP and saline groups. This study was registered at ClinicalTrials.gov and funded by the local hospital district. With 40 patients in each group, we had 80% power to detect a clinically important improvement in pain (1.5 cm on the 10-cm VAS pain scale).

RESULTS

There were no clinically important differences in the mean VAS pain or DASH scores among the groups at any timepoint. At 52 weeks, the mean difference in the VAS score for pain was -0.2 (95% CI -1.5 to 1.1; p = 0.75) for PRP versus saline and 0.5 (95% CI -0.7 to 1.7; p = 0.40) for autologous blood versus saline. The corresponding mean differences in the DASH score were 0.0 (95% CI -9.2 to 9.2; p > 0.99) and 7.7 (95% CI -1.3 to 16.7; p = 0.09) and those for grip strength were 1.4 kg (95% CI -3.3 to 6.1; p = 0.56) and -0.2 kg (95% CI -5.0 to 4.5; p = 0.92). No complications occurred because of the injections.

CONCLUSIONS

PRP or autologous blood injections did not improve pain or function at 1 year of follow-up in people with lateral epicondylitis compared with those who were given a saline injection. However, because the 95% CIs did not exclude the MCID in VAS scores for autologous blood versus saline at 52 weeks, it is possible that a larger study could identify a between-group difference that we missed, but the effect size of that difference (based on our findings), even if present, is likely still to be small. Until or unless future randomized trials convincingly show a benefit either to PRP or autologous blood injections, we recommend against their use in patients with lateral epicondylitis.

LEVEL OF EVIDENCE

Level II, therapeutic study.

Effect of platelet-rich plasma on rat Achilles tendon healing is related to microbiota

Background and purpose - In 3 papers in Acta Orthopaedica 10 years ago, we described that platelet-rich plasma (PRP) improves tendon healing in a rat Achilles transection model. Later, we found that microtrauma has similar effects, probably acting via inflammation. This raised the suspicion that the effect ascribed to growth factors within PRP could instead be due to unspecific influences on inflammation. While testing this hypothesis, we noted that the effect seemed to be related to the microbiota. Material and methods - We tried to reproduce our old findings with local injection of PRP 6 h after tendon transection, followed by mechanical testing after 11 days. This failed. After fruitless variations in PRP production protocols, leukocyte concentration, and physical activity, we finally tried rats carrying potentially pathogenic bacteria. In all, 242 rats were used. Results - In 4 consecutive experiments on pathogen-free rats, no effect of PRP on healing was found. In contrast, apparently healthy rats carrying Staphylococcus aureus showed increased strength of the healing tendon after PRP treatment. These rats had lower [corrected] levels of cytotoxic T-cells in their spleens. Interpretation - The failure to reproduce older experiments in clean rats was striking, and the difference in response between these and Staphylococcus-carrying rats suggests that the PRP effect is dependent on the immune status. PRP functions may be more complex than just the release of growth factors. Extrapolation from our previous findings with PRP to the situation in humans therefore becomes even more uncertain.

Lateral Elbow Tendinopathy: Development of a Pathophysiology-Based Treatment Algorithm

Lateral elbow tendinopathy, commonly known as tennis elbow, is a condition that can cause significant functional impairment in working-age patients. The term tendinopathy is used to describe chronic overuse tendon disorders encompassing a group of pathologies, a spectrum of disease. This review details the pathophysiology of tendinopathy and tendon healing as an introduction for a system grading the severity of tendinopathy, with each of the 4 grades displaying distinct histopathological features. Currently, there are a large number of nonoperative treatments available for lateral elbow tendinopathy, with little guidance as to when and how to use them. In fact, an appraisal of the clinical trials, systematic reviews, and meta-analyses studying these treatment modalities reveals that no single treatment reliably achieves outstanding results. This may be due in part to the majority of clinical studies to date including all patients with chronic tendinopathy rather than attempting to categorize patients according to the severity of disease. We relate the pathophysiology of the different grades of tendinopathy to the basic science principles that underpin the mechanisms of action of the nonoperative treatments available to propose a treatment algorithm guiding the management of lateral elbow tendinopathy depending on severity. We believe that this system will be useful both in clinical practice and for the future investigation of the efficacy of treatments.

Strong evidence against platelet-rich plasma injections for chronic lateral epicondylar tendinopathy: a systematic review

BACKGROUND

Chronic lateral epicondylar tendinopathy is frequent in athletes, and platelet-rich plasma (PRP) is being used increasingly in its treatment.

OBJECTIVE

To systematically review the literature on the efficacy of PRP injections for chronic lateral epicondylar tendinopathy.

METHODS

The databases of PubMed, EMBASE, CINAHL, Medline OvidSP, Scopus, Google Scholar, Web of Science and Cochrane Library were searched in October 2013. Inclusion criteria were a clinical diagnosis of chronic lateral epicondylar tendinopathy, a randomised controlled trial, an intervention with a PRP injection and the outcome measures described in terms of pain and/or function. One author screened the search results and two authors independently assessed the study quality using the Physiotherapy Evidence Database (PEDro) score. A study was considered to be of high quality if its PEDro score was ≥6. A best evidence synthesis was used to identify the level of evidence.

RESULTS

6 studies were included, of which four were considered to be of high quality. Three high-quality studies (75%) and two low-quality studies showed no significant benefit at the final follow-up measurement or predefined primary outcome score when compared with a control group. One high-quality study (25%) showed a beneficial effect of a PRP injection when compared with a corticosteroid injection (corticosteroid injections are harmful in tendinopathy). Based on the best evidence synthesis, there is strong evidence that PRP injections are not efficacious in chronic lateral epicondylar tendinopathy.

CONCLUSIONS

There is strong evidence that PRP injections are not efficacious in the management of chronic lateral elbow tendinopathy.