How effective are injection treatments for lateral epicondylitis?

To compare the effectiveness, after 3 months, of a single injection of platelet-rich plasma (PRP), glucocorticoid (GC), or saline in reducing pain in lateral epicondylitis.

Randomized, controlled, 3-group trial (RCT). Patients and outcome assessors were blinded to intervention group. Sample size was calculated to show a clinically important difference in patient-reported pain intensity at 12 months with 17 patients per group.

Tertiary study at the Rheumatology Unit at the Diagnostic Centre of the Region Hospital Silkeborg, Denmark.

Patients were referred to the Rheumatology Unit by general practitioners or other rheumatology or orthopedic departments. Inclusion criteria (verified by 1 physician) were lateral epicondylitis symptoms for ≥3 months (pain on the lateral side of the elbow and at the lateral epicondyle on palpation and during resisted dorsiflexion of the wrist), an ultrasound (US) color Doppler flow of ≥ grade 2 (range, 0-4). Exclusion criteria were age <18 years, treatment with GC injection within 3 months, inflammatory diseases, and conditions causing chronic pain. The 60 included patients had a mean age of 45 years, 52% were women, 58% had ≥1 previous injection, and 58% used analgesics.

The patients were randomized to a single US-guided injection of PRP, GC, or saline, administered by the 1 physician who had made the diagnosis. All patients were blindfolded during blood collection and injection. They all received an injection of 10 to 15 mL of lidocaine into the peritendon before the procedure. The PRP injection was of approximately 3.5 mL of autologous platelets (collected and centrifuged for 15 minutes from 27 mL of whole blood) buffered with 8.4% sodium bicarbonate, and immediately peppered into the common tendon origin. The GC injection (1 mL triamcinolon, 40 mg/mL + 2 mL lidocaine, 10 mg/mL) was delivered through 1 site. The saline injection (3 mL saline, 0.9%) was peppered in the same manner as the PRP injection. After treatment, the patients were asked to use the arm minimally for 3 days and then gradually to return to normal use.

The pain intensity scale of the Patient-Rated Tennis Elbow Evaluation (PRTEE) questionnaire was the main outcome measure (least to most pain = 0-50 points). The secondary end points included changes in functional disability using the functional section of the PRTEE, (least to most disability = 0-100 points), US changes in color Doppler signal and tendon thickness, and adverse events, which included pain after the injection. After 3 months, if the patient was unsatisfied with the result of treatment, he or she could be released from the study to seek other management.

Ten, 11, and 13 patients (58% of the total) dropped out of the PRP, GC, and saline groups, respectively, at the 3-month follow-up, thus evaluations were only made at 1 and 3 months. At 1 month, the mean reduction in pain for the PRP group versus the saline group was 1.2 (95% confidence interval [CI], -5.0 to 7.3); for the GC group versus the saline group was -8.1 (95% CI, -14.3 to -1.9); and for the GC group versus the PRP group, -9.3 (95% CI, -15.4 to -3.2). At 3 months, the mean reduction in pain for no group was significantly greater than for others (PRP vs the saline group, -2.7; 95% CI, -8.8 to 3.5; GC vs the saline group, -3.8; 95% CI, -9.9 to 2.4; GC vs the PRP group, -1.1; 95% CI, -7.2 to 5.0). The PRTEE disability scores at 1 month also favored the GC group versus saline, but no differences were found between any groups at 3 months. The improvement in Doppler grades at 3 months favored the GC group versus the saline group and the PRP group (P<0.0001 for both comparisons). Mean reduction in tendon thickness was greater for the GC group versus the saline group (P<0.0001) and the PRP group (P=0.002). PRP injections were found to be more painful than GC and saline injections. No adverse events leading to hospitalization, and no reports of infections resulting from the injections, occurred.

The dropout rate of 58% at 3 months showed that none of PRP, glucocorticoid, or saline injections adequately reduced the pain and disability of lateral epicondylitis.