Tennis elbow is a tendinopathy of the common extensor origin of the lateral elbow and is estimated to have an annual incidence of 1%–3% and a prevalence of 1.3%.1 It is characterized by tenderness over the lateral epicondyle of the humerus, normal range of motion of the affected elbow, and pain on resisted extension of the wrist or middle finger.2 The tendon insertion of the extensor carpi radialis brevis muscle is most commonly involved. Symptoms can persist for between 6 mos and 2 yrs, but usually resolve within 12 mos.3 Although tennis elbow is often self-limited, approximately 20% of cases are refractory to conservative care.4 Tennis elbow is now thought to be noninflammatory, and the pathologies are characterized by collagen degeneration, fibroblast proliferation, mucoid degeneration, and neovascularization.5
Treatment of tennis elbow includes relative rest, physical therapy (therapeutic exercise, massage, therapeutic ultrasound, lower power laser, etc.), analgesics, nonsteroidal anti-inflammatory drugs, glyceryltrinitrate patches, injection therapy (corticosteroid, hyaluronan gel, botulinum toxin, and autologous platelet-rich plasma), shock wave therapy, and even surgery.6–8 Previous studies demonstrated that corticosteroid injection is effective in the short-term, but is harmful in the long-term, and is more likely to have a recurrence.3,9 Moreover, in consideration of a degenerative lesion in tennis elbow, corticosteroid injection may not constitute an ideal agent. Although platelet-rich plasma injection showed promising results, its high cost limited its widespread clinical use. Since short-acting local lidocaine injection is commonly used in the management of myofascial pain syndrome,10 it might be effective in the treatment of tendinopathy, such as tennis elbow. In addition, in clinical practice, lateral epicondyle of the elbow is often injected with a combination of corticosteroid and lidocaine. However, if the injection is effective, it is not possible to discern whether the effect derives from corticosteroid or lidocaine.
The purpose of this study was to compare the short-term effect of corticosteroid injection and lidocaine injection in the treatment of tennis elbow. We hypothesized that lidocaine injection was as effective as corticosteroid injection in the management of tennis elbow. If this is the case, it might beneficially replace corticosteroid injection in the management of tennis elbow.
This was a prospective, double-blinded, randomized controlled study. The study project was approved by the hospital's ethics committee and was registered in Clinical Trial (Trial Number NCT02700906). After written informed consent was obtained, the participants were randomized into two treatment groups: group 1 (corticosteroid injection) and group 2 (lidocaine injection). The assignment scheme for randomization was generated using a table of computer-generated numbers by a statistician. The randomization order was sealed in an envelope until the eligible patients submitted a written informed consent. A research assistant who was blinded to the treatment opened the envelope and used the randomization scheme to assign patients into one of the treatment groups. The injection syringes were wrapped with opaque tape by a research assistant. Both the patients and the physician administering the injections did not know what kind of medicine was being injected. The outcome assessor was also blind to the content of the injections. This study conforms to all Consolidated Standards of Reporting Trials guidelines and reports the required information (see Checklist, Supplemental Digital Content, http://links.lww.com/PHM/A469).
From January 2014 to January 2016, patients with tennis elbow with at least 1 mo of duration of symptoms were recruited consecutively from the outpatient clinic of the Department of Physical Medicine and Rehabilitation and the Department of Orthopedics of Shin-Kong Wu Ho-Su Hospital by a physiatrist (L-FH) or an orthopedic surgeon (VH) who both had clinical experience for more than 30 yrs. The physiatrist ensured that participants met the eligibility criteria. Subjects were eligible if they were the following: (1) between the ages of 20 and 75 yrs; (2) experiencing unilateral lateral elbow pain for at least 1 mo; (3) severity of the worst pain over the preceding 24 hrs by visual analog scale (VAS) of 4 or greater; and (4) reproducibility of pain according to two or more of the following tests: palpation of the lateral epicondyle (or the common extensor origin) of the elbow, resisted wrist extension and forearm pronation with the elbow in extension, and static stretching of the pronated wrist in palmar flexion with the elbow in extension. The exclusion criteria were as follows: (1) generalized inflammatory arthritis, such as rheumatoid arthritis; (2) concurrent shoulder and/or neck pain and/or pain proximal to the elbow on the affected side; (3) wound or skin lesion on the lateral side of the affected elbow; (4) neurological symptoms or abnormal neurological findings in the affected arm; (5) pregnancy; (6) severe systemic medical conditions; (7) previous surgery to the elbow; (8) oral and/or topical nonsteroidal anti-inflammatory drugs in the previous 2 wks; (9) local corticosteroid injection in the previous 3 mos; and (10) oral glucocorticoids within the previous 6 wks.
Both treatments were administered by a physician who was familiar with injections for tennis elbow. For the corticosteroid injection, 1 ml of triamcinolone (10 mg/ml) was infiltrated or peppered (multiple injection) to the tender lateral epicondyle of the affected elbow. During the infiltration, the affected elbow was flexed at a right angle and forearm held in supination. The nondominant thumb was placed at the tender spot at the lateral epicondyle. The needle was trust in vertically near the thumb until it pierced the tendinous insertion and hit bone. By half withdrawing and reinserting the needle, the entire lesion was infiltrated.11 For lidocaine injection, 1 ml of 1% lidocaine was also peppered on the same area. Each participant received only one injection. After injection, the subjects were taught a stretch exercise of the common extensors of the wrist and fingers. The subjects were asked to perform this exercise five times in one session, two sessions per day, for 2 wks. Acetaminophen was prescribed as a rescue medication, and the amount dispensed was recorded at the conclusion of the study.
All assessments were performed by a masked assessor who was a trained research assistant. Participants were instructed not to reveal any details about the treatment to the assessor. The patients were evaluated at baseline, 2 wks, and 2 mos after the injection.
Demographic data, including age, sex, height, weight, employment status, and sports and leisure activity were recorded at baseline. A history was also taken from patients concerning the side of involvement, the duration of their symptoms, previous treatments (injections, physical therapy, etc.), and current pain medications.
The primary outcome measure was the composite score on the Patient-Rated Tennis Elbow Evaluation (PRTEE) and Disability of the Arm, Shoulder, and Hand (DASH). Patient-Rated Tennis Elbow Evaluation is a tennis elbow–specific questionnaire evaluating disease-specific pain and disability construct. Patient-Rated Tennis Elbow Evaluation includes a five-item pain scale, with “0” indicating no pain and “10” indicating the highest level of pain, and a 10-item functional disability scale, with “0” indicating no difficulty and “10” indicating the greatest level of difficulty (unable to complete). The scores range from 0 (no pain or disability) to 100 (extreme pain and disability). Patient-Rated Tennis Elbow Evaluation exhibited excellent reliability (interclass correlation coefficient for pain was 0.96, for function was 0.92, and for composite score was 0.96) and sensitivity to change.12,13 Disability of the Arm, Shoulder, and Hand is a self-report questionnaire comprising 30 items, which focuses on symptoms and the ability to perform certain upper limb activities on a five-point Likert-type scale. The scores range from 0 (the best) to 100 (the worst). The reliability of DASH was 0.96, and the validity was greater than 0.70.14
Secondary outcome measures included VAS for pain and grip strength. Visual analog scale for pain was obtained using a 10-cm-long horizontal line, with 0 cm on the left, indicating no pain, and 10 cm on the right, indicating the most severe pain. The reliability for VAS pain was 0.94.15 Grip strength is a commonly used objective measure of tennis elbow–related disability, with good test-retest reliability (Pearson correlation, r ≥ 0.80) and validity (±3%) measures.16 The participants sat in a chair with their shoulder flexed at 90 degrees, their elbows extended, and their forearms in a neutral position. All participants were instructed to squeeze the dynamometer and cease squeezing before the onset of pain. The mean of the three replications was recorded, with each measure separated by a 60-sec interval.
Complications after injection were recorded. Postinjection pain was reported by the patient in telephone 1 wk after injection. The patients reported “yes” if they experienced increased pain within this week compared with preinjection pain or reported “no” if the pain got relieved or remained unchanged.
Numbers were reported between groups for the categorical variables. The Fisher's exact test was used for group comparison of sex, work, and exercise habits. Means and standard deviations were reported for the continuous measurements. The Mann–Whitney U test was used for group comparison. For the outcome measurement obtained from VAS for pain, grip strength, PRTEE, and DASH, the General Linear Model Repeated Measures, which has tests of between-subjects effects (group: corticosteroid injection and lidocaine injection) and tests of within-subjects effects (evaluation time: pretreatment, 2 wks after treatment, and 2 mos after treatment), were performed and analyzed by the intention-to-treat principle. All statistical significance level was set at a P value of less than 0.05, and the Statistical Package for the Social Sciences (Version 19.0; SPSS Inc, Chicago, IL) was used for all statistical analyses. The sample size was calculated based on PRTEE. Power calculation were performed by G*power (Version 184.108.40.206; Germany).
We recruited 70 participants with tennis elbow for this study. Among them, five were excluded because of the exclusion criteria and three declined to sign the consent form. One of the subjects in the corticosteroid injection group (CI group) was lost to follow up at the 2-mo evaluation. As a result, 30 participants in the CI group, and 31 participants in the lidocaine injection group (LI group) completed the entire study (Fig. 1). The mean (SD) duration of symptom of all participants was 3.8 (4.5) mos were found (Table 1). No significant group differences regarding age, sex, weight, height, side of involvement, disease duration, work, exercise, PRTEE, DASH, VAS for pain, and grip strength were found (Table 1).
Primary Outcome Measures
In the between-group comparison, no significant statistical differences were found regarding PRTEE, although the P value for the interaction (time by group) was 0.061, which was close to 0.05, in favoring of the CI group (Table 2). The within-group comparison showed decrease in PRTEE score (improved condition) with increased time after treatment for both groups (Table 2). In the between-group comparison regarding DASH, similar to PRTEE, no significant statistical differences were observed, although the P value for the interaction (time by group) was 0.059, which was close to 0.05, in favoring of the CI group (Table 2). The within-group comparison revealed a significantly decreased DASH score in both groups, suggesting similar improvement in pain and disability in both groups (Table 2).
Secondary Outcome Measures
The between-group comparison showed no statistically significant difference in VAS for pain after treatment (Table 2). The within-group comparison found that VAS for pain decreased significantly at 2 wks and 2 mos after treatment in both groups (Table 2). In the between-group comparison with regard to grip strength, no significant difference was observed. However, a significant increase in grip strength was found after treatment in both groups (Fig. 2, Table 2).
Postinjection pain was reported by 11% in the CI group and 9% in the LI group. Except for postinjection pain, no other adverse effects were found.
In clinical practice, physicians often use a combination of corticosteroid suspension with local anesthetics during local soft tissue injection. However, if the injection is effective, it is not possible to discern which medicine contributes the effect. In this study, it was found that lidocaine was as effective as triamcinolone.
The pharmacological actions of corticosteroid and local anesthetic are different. Corticosteroids, such as triamcinolone, impart both anti-inflammation and direct analgesic effects through reducing proinflammatory mediators and influencing the cells involved in inflammatory responses.17 The onset of action of corticosteroid is 24–48 hrs, and the duration of action is approximately 2–3 wks.18 Coombes et al.19 suggested that corticosteroids might have an analgesic effect on the neuropeptides, such as substance P and calcitonin gene-related peptide, which are increased in tendinopathy. Local anesthetics, such as lidocaine, act by membrane stabilization, causing a reversible block to conduction along nerve fibers, with a preferential block to small fibers that carry pain and autonomic impulses. The effects occur within seconds, and the duration of the block is approximately 30 mins. Although the pharmacologic action is dissimilar, both corticosteroid and local anesthetic produce similar effects with regard to pain and subsequently improvement in strength and upper limb function.
Corticosteroids have been used for local injection for many decades. Although the effectiveness of local treatment has been well documented, during recent years, adverse effects and complications of corticosteroids have become increasingly obvious. For example, in the report by Smidt et al.,3 corticosteroid injection was effective for tennis elbow up to 6 wks, but more recurrence of symptoms was noted at 1-yr follow-up. In a review article by Foye et al.,18 approximately 15% of patients reported adverse effects regarding corticosteroid injection for tennis elbow. Among them, postinjection pain was most common (10%), followed by skin atrophy (2%), and skin depigmentation, localized erythema with warmth and facial flushing (<1%). Although rupture at tendon origin (lateral epicondyle) due to corticosteroid injection was reported, contribution by underlying tendon pathology cannot be ruled out.20 In our study, postinjection pain was 11% in the triamcinolone injection group and 9% in the LI group, and the pain mostly occurred within 2 to 4 days after injection. Except for postinjection pain, no other adverse effects were found in our study.
In a systematic review by Dean et al.,21 local administration of glucocorticoid reduced cell viability, cell proliferation, and collagen synthesis in vitro. In addition, increased collagen disorganization and necrosis, as well as reduced mechanical properties, were found in vivo. Previous in vitro and in vivo studies also showed that dexamethasone injection could induce nontenocyte differentiation of human tendon stem cells, leading to formation of nontendinous tissues (e.g., fatty tissues, bony tissues, and cartilage-like tissues), which make tendon susceptible to rupture.22 Overall, significant long-term damage to tendon cells and tissue was associated with glucocorticoid injections.21
Although the adverse effects of lidocaine injection to the tendon are not commonly known, they have been previously reported. For example, Piper et al.23 found that the viability of cultured bovine tenocytes was significantly decreased after 30-min exposure to 1% or 2% lidocaine. In an in vitro and in vivo study of lidocaine action on torn rotator cuff tendons, Honda et al.24 showed that lidocaine was cytotoxic to tenocytes, could induce apoptosis, decrease biomechanical properties, and delay collagen organization of the tendons. In addition, Yang et al.25 reported that 1% lidocaine synergistically increased the deleterious effects of triamcinolone acetonide on cultured rat tenocytes. Because all of the adverse effects of lidocaine came from in vitro or in vivo studies, whether these results could be applied in human beings or in clinical practice remains unknown. However, in considering the possible adverse effects of lidocaine to the tendon, even local injection of tendon or entheses with lidocaine should be performed with caution.
There have been some studies relating to corticosteroid injection for treatment of tennis elbow. Four study groups compared a mixture of corticosteroid and local anesthetic versus local anesthetic or normal saline, and found mixture of corticosteroid injection was not superior to placebo injection.26–29 In a systematic review, Coombes et al.9 showed that corticosteroid injection was more effective than other treatments (including saline injection, local anesthetic injection, nonsteroidal anti-inflammatory drugs, physiotherapy, transverse friction massage, etc.) in the short term, except two studies.26,27 In these two studies, patients with relatively short symptom duration were enrolled. Comparing the effect of corticosteroid (methylprednisolone) injection only with local anesthetic (procaine) only, Mardani-Kivi et al.30 showed that corticosteroid injection was more effective at 3-wk visit, but the recurrence rate was higher than that of anesthetic group. In our study, we found that triamcinolone injection was not significantly better than lidocaine injection at 2-wk and 2-mo follow-up. In the study by Mardani-Kivi et al.,30 the average symptom duration was 17 mos, which was different from our study (2.7 mos and 4.2 mos). It is possible that the benefits of corticosteroid injection are in people with tennis elbow with longer duration of symptoms.
Coombes et al.19 conducted a 2 × 2 factorial, randomized, controlled trial in 165 patients with unilateral lateral epicondylalgia. The study included the following four groups: corticosteroid injection (mixed with lignocaine) only, corticosteroid injection (mixed with lignocaine) plus physiotherapy, placebo (saline) injection only, and placebo injection plus physiotherapy. After a 1-yr follow-up, they found that among patients with unilateral epicondyalgia, the clinical outcome was worst in CI group.19 In another study, Smidt et al.3 divided patients with tennis elbow into the following three treatment groups: corticosteroid injection, placebo injection, and a wait-and-see. The results showed that corticosteroid injection was more effective at 6 wks but became less effective at 52 wks (worse than placebo injection or wait-and-see groups). Because there was no placebo group or wait-to-see group in our study, it cannot be concluded whether the current two injections were any better than natural recovery.
Technique of injection may affect clinical outcomes. Altay et al.28 proposed that clinical improvement of tennis elbow might be due to the use of the peppering technique rather than lidocaine itself. Because peppering or an infiltration technique can distribute medicine more evenly over the lesion site, it can cover the whole lesion (enthesis). The possible adverse effects are negligible because one injection dose of medicine during the peppering technique is very small. However, the peppering technique could induce more pain during and after the injection, because of more frequent touching of the periosteum during the procedure.
There is increase of ultrasound for the detection of tennis elbow in clinical practice. However, the accuracy of ultrasound to diagnose tennis elbow is highly dependent on numerous variables, such as operator training and experience, equipment, and stage of pathology. For treatment, ultrasound-guided injection may be more accurate and specific. However, more researches comparing between ultrasound-guided and palpation-guided injection to treatment of tennis elbow are needed.
There are three main limitations of the study. First, because we followed up only 2 mos after injection, a long-term follow-up needs to be conducted in the future. Second, we compared only corticosteroid injection and lidocaine injection, and there was no placebo (i.e., normal saline) injection group or a wait-to-see group. It cannot be concluded whether the current two treatments are any better than natural recovery. Third, the sample size of 62 patients was calculated for 69% power, α value of 0.05, β value of 0.69, and anticipated effect size of 0.32 that a type 2 error is possible. Even so, this study may be worthwhile reporting because of a double-blinded, randomized controlled design.
In this double-blinded, randomized controlled trial, one injection of corticosteroid or lidocaine using the peppering technique could improve pain, grip strength, and functional outcomes in patients with tennis elbow, and lidocaine injection produced similar effects to corticosteroid injection. In consideration of the relatively more adverse effects of corticosteroid injection, such as tendon rupture, facial flush, subcutaneous atrophy, or skin depigmentation, for patients with tennis elbow, it may be advantageous to attempt local lidocaine injection first.
The authors thank Chyi-Huey Bai, PhD, professor from the Department of Public Health, College of Medicine, Taipei Medical University, for her valuable assistance in the statistical analysis of this study.
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Corticosteroid; Lidocaine; Tennis Elbow
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