The effect of Shock wave on the treatment of Plantar Fasciitis

Extracorporeal shock wave therapy is effective in treating chronic plantar fasciitis

A meta-analysis of RCTs

Jiale Sun, MDa, Fuqiang Gao, MDb, Yanhua Wang, MDc, Wei Sun, MDb,∗, Baoguo Jiang, MDc,∗, Zirong  Li, MDb

Abstract

Background: Plantar fasciitis (PF) is the most common reason for heel pain. The efficacy of extracorporeal shock wave therapy

(ESWT) as an ideal alternative to conservative treatments and surgery is controversial, and almost all previous articles compared general ESWT with placebo without indicating the kind of shock wave. We undertook a meta-analysis to compare the efficacy of general ESWT, focused shock wave (FSW), and radial shock wave (RSW) with placebo, to assess their effectiveness in chronic PF.

Methods: The PubMed, Medline, EmBase, Web of Science, and Cochrane library databases  were searched for studies comparing FSW or RSW therapy with placebo in chronic  PF. Clinical outcomes  included the odds ratios (ORs) of pain relief, pain reduction,  and complications. Relevant data were analyzed using RevMan v5.3.

Results: Nine studies involving 935 patients were included. ESWT had higher improvement rates than the placebo group (OR 2.58,95% confidence interval [CI] 1.97–3.39, P<.00001). ESWT had markedly lower standardized mean difference than placebo, with heterogeneity observed (standardized mean difference 1.01, 95% CI    0.01 to 2.03, P=.05, I2 =96%, P<.00001). FSW and RSW therapies had greater therapeutic success in pain relief than the placebo group (OR 2.17, 95% CI 1.49–3.16, P<.0001; OR 4.63,

95% CI 1.30–16.46, P=.02), but significant heterogeneity was observed in RSW therapy versus placebo (I2 =81%, P=.005).

Conclusion: This meta-analysis suggested that FSW therapy can relieve pain in chronic PF as an ideal alternative option; meanwhile, no firm conclusions of general ESWT and RSW effectiveness can be drawn. Due to variations in the included studies, additional trials are needed to validate these conclusions.

Abbreviations:  ESWT = Extracorporeal shock wave therapy, FSW = focused shock wave, ORs = odds ratios, PF = plantar fasciitis, PRISMA = Preferred Reporting Items for Systematic Reviews and Meta-Analyses, RCTs = randomized controlled trials, RSW = radial shock wave, SMD = standardized mean difference.

Keywords: Extracorporeal shock wave therapy, heel pain relief, meta-analysis

1. Introduction

Plantar fasciitis (PF) is a foot disease, and the most common cause of  heel pain,  accounting  for  about  11%  to  15%  of  clinical symptoms requiring treatment.[1]  Although  the suffix “ –itis ” implies an inflammatory condition, mounting evidence indicates that this foot disorder is associated with degenerative changes, and  should  be  appropriately  classified  as  a   “Fasciosis”  or “Fasciopathy.”[1,2]   Patients with  PF  may  experience the most serious heel pain with the first few steps in the morning or after a period  of   rest.[1,2]     The   treatment  options  for   relieving  PF symptoms include activity modification, plantar fascia stretch, ice massage, night splints, no steroidal anti-inflammatory drugs combined   with   other   treatment   modalities,   local    steroid injections, Extracorporeal Shockwave therapy,  and  surgery.[3] Approximately  10%   of   PF  patients  cannot  be  relieved  by conservative therapy, whose long course is not satisfactory.[4] In addition,  surgical treatment is considered the last intervention because of serious injury, risks, and postoperative complications. Extracorporeal shock wave therapy (ESWT) has been widely used as an alternative treatment option for PF for decades due to its noninvasive nature, fast recovery time, and convenience for daily life of patients.[5,6]   The specific mechanisms of ESWT  in treating musculoskeletal pain remain unclear; however, multiple studies have shown that it can  destroy sensory unmyelinated nerve  fibers,  and  stimulate  neovascularization  and  collagen synthesis in degenerative tissues.[7] Recently, both focused shock wave  (FSW)  and  radial  shock  wave  (RSW)  therapies were introduced as treatment options for PF. RSW dispersed from the applicator does not  concentrate on  the tissue compared with FSW.[8] Several studies have demonstrated the function of ESWT in relieving heel pain. However, there were positive and negative results. Furthermore, some previous meta-analyses compared ESWT and sham or other therapeutic methods, without distinguishing which ESWT   type is effective.  It is uncertain whether general ESWT, including FSW and RSW therapies, is effective in relieving plantar heel pain. Such debate may be further acknowledged by our meta-analysis combined with previous analysis, aiming at providing useful information on efficacy of ESWT for the treatment of chronic PF.

2. Materials and methods

 This meta-analysis was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta- Analyses (PRISMA) guidelines.[9] Ethical approval for this study was unnecessary, as a review of existing literature not involving the handling of individual patient data.

2.1. Date sources and study selection

The PubMed, Medline, EmBase, Web of Science, and Cochrane library databases were searched up to July 2016, for comparative studies involving shock wave in the management of pain relief from plantar fasciitis. The search terms were: “extracorporeal shock wave therapy” OR  “focused extracorporeal shock wave therapy” OR  “radial extracorporeal shock wave therapy” AND “plantar fasciitis” OR  “plantar fasciopathy” OR  “heel pain.” Then, the articles were searched by abstract and title. Publication language was limited to English. The reference lists of all eligible studies and relevant reviews were manually searched for any additional trials.

  2.2. Inclusion criteria

Studies that met the following criteria were included in the current meta-analysis: investigations of patients suffering from heel pain and diagnosed with chronic plantar fasciitis; studies involving the comparison between ESWT without anesthesia and sham therapy as control; randomized controlled trials (RCT).

  2.3. Data extraction and quality assessment

Data from the obtained articles were abstracted independently by 3 investigators (J.S.,  F.G., and W.Y.), including author’s name, year of publication, trial design, total participants and allocation, details of intervention (FSW or RSW,  density of shock wave, and time of treatment) and control groups, and trial outcomes and results. Cochrane Risk of Bias Tool was used to assess the quality of clinical trials (Figs. 1 and 2). Discrepancy was resolved by discussing with other investigators and contacting the article’s authors if necessary.

 2.4. Statistical analysis

Review Manager Software (Revman v5.3) was used to analyze experimental data from the included trials. Odds ratios (ORs) of successful treatments were assessed for dichotomous data. Heterogeneity among studies was estimated using the I2 statistics;

model was used when I2   <50%; otherwise, the random-effects model was adopted. P<.05 was considered statistically significant.

3. Results

3.1. Study inclusion

The literature search identified a total of 326 articles, of which145 were considered to be relevant; 37 clinical RCTs   were

Screened. After assessing the abstracts and full text articles, 10 studies were excluded because of comparisons between focused or radial shock wave and  other treatments rather than  sham therapy;[10–19]   6 were excluded for comparisons between different  intensities,[20–25]   2  for  comparisons between shock wave therapy combined with other therapies and sham therapy,[26,27]  4 for comparisons between different methods of shock wave therapy,[28–31]  5 for applying local anesthesia totally,[5,6,32–34]   and  1  for  lacking  the success rate.[8]   Finally, 9 studies, including 6 reports comparing FSW  therapy with a placebo,[35–40]   and  3  comparing RSW,[41–43]   were eligible for data extraction and meta-analysis based on inclusion and exclusion criteria. These articles involved 935 patients (Fig. 3) (Table 1).

3.2. Success or improvement rates

Therapeutic success was defined as a decrease in visual analogue scale (VAS) score from baseline larger than 50% or 60%, or VAS score of less than 4 cm after intervention, according to the included studies. In comparison, general ESWT had higher improvement or success rates than placebo as assessed by a fixed effects model (OR 2.58, 95% confidence interval [CI] 1.97–3.39, P< .00001, I 2 = 38%) (Fig. 4). According to the different shock wave types, a subgroup analysis of FSW and RSW therapies was performed. The FSW group involved 474 patients with 244 events, indicating that FSW therapy had greater improvement or success rates than placebo as assessed by a fixed-effects model (OR 2.17, 95% CI 1.49–3.16, P< .0001, I 2 = 0%) (Fig. 5). The RSW   therapy group  involved  461  patients with  262  events, suggesting that RSW  therapy had higher pooled ORs  (OR  4.63,95% CI 1.30–16.46, P=.02) than placebo, but significant heterogeneity was observed (I2 =81%,  P=.005) (Fig. 6).

3.3. Reduction in pain scales

 Only 4 trials provided adequate information regarding reduction in pain scale with standard error. Of  these trials, 3 compared FSW  therapy with placebo,[37–39]  whereas 1 comparatively assessed RSW  therapy and placebo.[41]  Significant heterogeneity was observed in  the comparisons of  reduction in  pain  scale. General ESWT  had greater reduction in pain scale than placebo (standardized mean difference [SMD]  1.01,  95%  CI    0.01  to 2.03,  P=.05)  (Fig. 7), but 95%  CI  covered the value of 0,  as analyzed by a random-effects model.

3.4. Complications

Seven of 9 included studies described complications of ESWT; there were no serious adverse events, such as hematomas, infections, and abnormal musculoskeletal events, recorded during patient follow-up.  A few patients had feelings of discomfort, pain, swelling, and bruise during or after treatment, which may be considered intensity-related adverse events. These findings indicated that ESWT is a safe and effective treatment.

4. Discussion

Unlike previously published meta-analyses that did not distinguish shock wave types, the current meta-analysis pooled comprehensive data  on  FSW  and  RSW  therapies for  chronic PF,  and determine whether general ESWT,  FSW  therapy, and RSW therapy are effective treatments for chronic PF. In addition, few studies have compared the effects of FSW  and RSW therapies, respectively, with  those  of  placebo.  In  this  meta- analysis, ESWT and RSW therapy for chronic PF might be more effective than  placebo  and  FSW  therapy,  as  safe  alternative options.

General  ESWT  was  shown  to  be  effective and  safe in  the treatment of  chronic  PF  in  a  comprehensive comparison  of success or improvement rates including both shock wave types with controls. However, Speed et al[40]  and Marks et al[38]  found no  significant  difference between ESWT   and  sham  therapy. General ESWT  was probably more effective, according to the comparisons of pain scale reduction and significant heterogeneity that resulted in a wider range of SMD. Nevertheless, differences were observed in ESWT  compared with sham therapy. 

The FSW therapy is a traditional alternative option to operation, and was introduced in 1995. FSW devices generate energy focusing on a small region with the maximum energy level, which can penetrate some centimeters subcutaneously. [8] In the current meta-analysis, significant differences in success or  improvement rates were observed in FSW therapy for chronic PF compared with sham therapy, and reduction in pain scale in FSW therapy (SMD 1.29,

[44–46] 2 = 87% in random-effects model) (Fig. 8) was higher than in the placebo groups. However, Speed et al found no significant difference between FSW and sham therapies. [40] [38] and Marks et al  The RSW therapy is a relatively new method that was introduced in 2001. [8] Compared with FSW, RSW  evices disperse the shock wave at the skin surface and distribute the energy radially into larger treatment tissue areas. Therefore, the

radial technique can be used to treat the painful region instead of a point, and an advantage of RSW therapy is extended treatment area.[8,41,43,47] We found that RSW therapy effectiveness may be due to significant heterogeneity; therefore, no solid conclusions can be drawn, although all included studies demonstrated the effectiveness of RSW  therapy in chronic PF.

Most  observed heterogeneity appeared to  be  attributed to clinical practice or trial’s methodology. First, in a comprehensive comparison of  both shock wave types in reducing pain scale, variations  of  follow-up  time  in  individual  studies may  have influenced the results. Gollwitzer et al[37]  trail followed up for 3 months and the other trial for more than 6 months. Excluding Gollwitzer et al’s study revealed ESWT efficacy (SMD 0.57, 95% CI  0.12–1.01,  P=.01) compared with placebo. Secondly, analyzing  the success rates of  RSW  therapy and  considering the far better effect in the study by Ibrahim et al,[42]  we concluded that the high difference in participant numbers between the 3 trials evaluating RSW  might have influenced the results. However, even excluding the Ibrahim et al’s trial, Gerdesmeyer et al[41]  and Malay et al[43]  still showed efficacy for RSW therapy (OR  2.39,  95% CI  1.57–3.65,  P<.0001) compared with sham therapy. Thirdly, variations in success criteria in each study might have  influenced the  success rates.  Malay   et  al[43]    considered therapeutic  success as a decrease of 50% or more in VAS  score from  baseline to  the  third  visit,  with  a  VAS   score    4 cm; Gerdesmeyer et al[41]   and Ibrahim et al[42]   defined therapeutic success as a decrease in VAS score from baseline larger than 60%. By excluding Malay  et al’s study, the efficacy of RSW  therapy (OR 18.34, 95% CI 0.14–2413.75) compared with sham therapy remained, but heterogeneity was observed (I2 =90%,  P=.001). Subgroup analysis based on participant numbers was not carried out due to insufficient data required for further confirmation.

The current meta-analysis included 9 studies not applying local anesthesia to most participations in the RCTs, because according to some literatures, application of local anesthesia would affect the efficacy of shock wave therapy.[30,48]  Some previous meta- analyses did not take this into account.  Meta-analyses by Yin et al,[49]    Dizon  et al,[50]    and Zhiyun  et al[51]   did not exclude studies applying local  anesthesia, and more inaccurate results may  appear.  Furthermore, almost  all  previous meta-analyses investigated common effectiveness of ESWT  in chronic PF, not differentiating the shock wave type, lacking efficacy data about FSW or RSW  compared with placebo, respectively. The studies by Yin  et al[49]Aqil et al,[52]   and many other studies compared ESWT (including FSW and RSW therapies) with placebo, which may make it difficult to accurately evaluate the efficacy of general ESWT  for chronic PF if the 2 shock wave types have different effectiveness levels.

Numerous studies have evaluated the efficacy of FSW therapy, but yielded inconsistent results. Speed et al[40]  and Marks et al[38] indicated that FSW has no significant treatment effect in patients, which appeared to be the placebo effect. However,  Gollwitzer et al in 2007[36]  and 2015,[37]   respectively, enrolled 40 and 246 patients undergoing treatment with an intensity of 0.25mJ/mm2, and  success rates in  pain  relief were 11/20 and  68/125, respectively, higher than with placebo therapy. In 2003, Rompe et al[39]   enrolled 45 running athletes suffering from chronic PF and demonstrated the beneficial effects of  FSW  therapy. Therefore, FSW may be considered an effective and noninvasive treatment method. This meta-analysis suggests that FSW therapy should be recommended as remedial treatment after failure of traditional conservative therapy and before operation based on the different included studies. Moreover, the current meta-analysis compared FSW or RSW therapy with sham therapy, and different indicators to evaluate general ESWT   effectiveness; due to significant heterogeneity, RSW therapy may probably have better effectiveness, and no firm conclusions that general ESWT (including FSW and RSW therapies) is effective could be drawn.  In addition, we could not determine which shock wave type is more effective. There was only 1 study, the study by Lohrer et al,[8]   comparing focused versus radial  extracorporeal shock  waves in  plantar fasciitis, demonstrating the superiority of  FSW  therapy over RSW therapy. Due to the limited literature available on FSW versus RSW therapy, whether FSW is more effective than RSW remains to be studied. This meta-analysis had 4 limitations. First, we included only studies written in English, and some relevant studies in other languages may have been missed. Second, although we estimated the various articles based on inclusion and exclusion criteria, and also Cochrane  Risk  of  Bias Tool,  the sample sizes of  several included  studies were small,  and  a  small  proportion  of  the participants involved used local anesthesia because of unendurable pain rather than routine administration, which limited the statistical power of this meta-analysis. Third, some articles lacked data on functional recovery after shock wave therapy, and we could not estimate this parameter. Therefore, further assessment of comparative efficacy and functional recovery between FSW and RSW therapies is required. Fourth, more multicenter RCTs comparing FSW and RSW   therapies are required to further confirm the comparative effectiveness of focused and radial shock wave therapies for treating chronic plantar fasciitis.

5. Conclusions

 Focused shock wave therapy appears to be associated with higher success rate and  greater pain  reduction compared with sham therapy in chronic plantar fasciitis patients. However,  due to limitations of the included studies, more large-sample and high- quality  clinical  trials and  systemic reviews are  warranted to demonstrate the efficacy of general ESWT  (including FSW  and RSW therapies) and determine whether RSW therapy is an ideal alternative therapeutic method to  conservative treatment and surgery.

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