Calcific tendinopathy of the shoulder:
Daecke, et al. (2002) conducted a study to evaluate the long-term effects and any complications of ESWT for calcific tendinitis (CT) of the shoulder.9 The 4-year outcome was determined in a prospective study of 115 patients who presented with painful CT for >12 months and conservative treatment (physiotherapy and subacromial steroid injections) for at least 6 months without effect. For this study, the CT patients had persistent shoulder pain associated with calcareous deposits in the supraspinatus or infraspinatus tendon. Patients were treated with high-energy ESWT by 2 different protocols. One day prior to ESWT, each patient underwent an anteroposterior x-ray in internal and external rotation of the shoulder and a functional examination of the shoulder was performed and documented with use of the Constant-Murley (CM) score. One session (group A, n = 56) or 2 sessions (group B, n = 59) of high-energy shockwave therapy were administered to each patient. The shockwave intensity was increased, within the first 300 impulses, from low energy up to an energy flux density (EFD) of 0.3 mJ/mm2. Outcome was determined by functional examination, x-rays of the shoulder, and the patients’ own assessments at 3 months, 6 months, and 4 years post-therapy. Results at 6-months showed that the level of success achieved in pain relief and CM score was energy-dependent and that there were significant differences in radiologic changes between the groups. Four years following ESWT, 20% of the entire patient population had undergone surgery on the involved shoulder. The effects of ESWT not followed by any other therapy within the first 6 months were evaluated in 59% (n = 68) of the original 115 patients. Frequency of subjective success (increase in pain relief) was seen in 78% of patients in group A and 87% in group B. The CM score increased from a mean of 45 pre-treatment to 88 in group A and 85 in group B post-treatment. Radiologic changes were found in 93% of patients in each group. The authors concluded that the failure rate after ESWT was high, but the treatment was successful for 70% of the patients in this study and no long-term complications were seen.
Ioppolo, et al. (2012) noted that limited evidence was available for the useful range of ESWT doses in the treatment of supraspinatus calcifying tendinitis (SCT). The authors published a single-blind randomized clinical trial to compare 2 different ranges of EFD in treatment of SCT with ESWT.12 Forty-six patients with SCT were randomized to 2 groups that received different therapeutic energy doses of ESWT: (1) group A (n=23) received ESWT at an energy level of 0.20 mJ/mm², and (2) group B (n=23) received ESWT at an energy level of 0.10 mJ/mm². Both groups received 2,400 pulses once a week for 4 weeks. The change in mean CM score from baseline to 3 and 6 months was the primary endpoint. The change in the mean visual analog scale (VAS) scores from baseline to 3- and 6-months post-treatment and radiographic change in size of calcium deposits were evaluated as secondary endpoints. At 12 months, pain relief was assessed using a numeric rating scale. Results showed that significant clinical improvement based on mean CM scores was observed after 6 months in group A (sample mean=79.43, SD=10.33) compared with group B (sample mean=57.91, SD=6.53). Also, after 6 months, a significant decrease in VAS scores was found in group A (sample mean=2.09, SD=1.54) compared with group B (sample mean=5.36, SD=0.78). The disappearance of calcific deposits was similar in both groups. The authors concluded that for treatment of SCT, an energy level of 0.20 mJ/mm² for ESWT appears to be more efficacious than an energy level of 0.10 mJ/mm² regarding pain relief and functional improvement. However, the results are limited secondary to small sample size and lack of a control group.
A prospective randomized trial of calcifying tendinitis of the rotator cuff by Albert, et al. (2007) compared the efficacy of dual treatment sessions delivering 2500 extracorporeal shock waves at either high- or low-energy.1 Patients were eligible for the study if they had > 3 months history of calcifying tendinitis of the rotator cuff, with calcification measuring 10 mm or more in maximum dimension. The change in the CM score was the primary outcome measure. Eighty patients were enrolled in the study (40 in each group). Patients were re-evaluated at a mean of 110 (41 to 255) days post-treatment when the increase in CM score was significantly greater (t-test, p = 0.026) in the high-energy treatment group than in the low-energy group. In the high-energy group, the improvement from baseline was significant with a mean gain of 12.5 (-20.7 to 47.5) points (p<0.0001). In the low-energy group, the improvement was not significant. Total or subtotal resorption of the calcification took place in 6 patients (15%) in the high-energy group and 2 patients (5%) in the low-energy group. The investigators concluded that high-energy shock-wave therapy significantly improves symptoms in refractory calcifying tendinitis of the shoulder after 3 months of follow-up; however, the calcific deposit remains unchanged in size in most patients.
Verstraelen, et al. (2014) noted that ESWT was a possible alternative to surgery after failure of conservative treatment for calcifying tendinitis of the shoulder. The authors performed a systematic review and meta-analysis of randomized trials to compare the CM score and amount of resorption of calcifications in patients treated with high-energy ESWT vs. those treated with low-energy ESWT at 3 and 6 months.21 Medline® (through PubMed®), EMBASE (through OVID), Cinahl (through EBSCO), Web of Science, and the Cochrane Central Register of Controlled Trials (CENTRAL), were systematically searched. Included studies consisted of randomized controlled trials (RCTs) that compared high-energy ESWT (>0.28 mJ/mm2) with low-energy ESWT (<0.08 mJ/mm2). The primary outcome measure, the CM score, was determined by comparing mean functional outcome scores between the groups. Secondary outcomes were determined using odds ratios, when appropriate data were pooled. Five RCTs (359 participants) were included. All 5 RCTs, showed greater improvement in functional outcome (CM score) for patients treated with high-energy ESWT vs. treatment with low-energy ESWT at 3 and 6 months. The 3-month mean difference was 9.88 (95% CI, 9.04-10.72, p<0.001; 6-month data could not be pooled). Also, high-energy ESWT more often resulted in complete resorption of the calcium deposits at 3 months. The corresponding odds ratio was 3.40 (95% CI, 1.35-8.58) and p = 0.009 (6-month data could not be pooled). High-energy shock wave therapy appears to be more likely to result in improved CM score and resorption of the calcium deposits compared with low-energy therapy.
Bannuru, et al. (2014) conducted a systematic review using CENTRAL, EMBASE, Web of Science, and Google Scholar (n=28 RCTs/1307 subjects) to assess the efficacy of ESWT in patients with CT (n=1134) and non-CT (n=173).4 Outcome measures included pain (VAS), functional assessment (CM score), and resolution of calcium deposits, which was evaluated only in CT trials. Of the 28 RCTs, 20 compared different ESWT energy levels to placebo and 8 compared ESWT to other treatments. The quality of trials was reported as variable and generally low. Trials included multiple sources of bias and heterogeneity, including different ESWT regimens and ESWT devices. The heterogeneity of the included trials and general paucity of similar trials resulted in the inability of the authors to perform a meta-analysis of these studies. Results show that high-energy ESWT (EFD ≥0.28 mJ/mm2) was efficacious for treatment of CT of the shoulder regarding reducing pain, improving function, and inducing resorption of calcifications. Lower-energy ESWT (EFD <0.28 mJ/mm2) was not as effective as high-energy ESWT; however, it did improve shoulder function in patients with CT. Results for pain and reduction in calcification were inconclusive with low-energy ESWT. Irrespective of energy dose, ESWT did not appear to be efficacious in treating non-CT. Adverse effects of ESWT included localized swelling, redness, or small hematomas and were reported to be dose dependent. The authors concluded that high-energy ESWT appears effective for improving pain and shoulder function in chronic calcific shoulder tendinitis and can result in complete resolution of calcifications. However, larger RCTs as well as standardization of energy levels and treatment protocol were needed to further define the role of ESWT for treating CT of the shoulder.
Peters, et al. (2004) investigated clinical (pain, mobility) and radiological (resolution of calcium deposits) efficacy of different energy levels of ESWT in CT of the shoulder.17 The study included 90 subjects with radiographically verified CT of 1 shoulder, mean age 52+/-6 years (range 29-65 years; females:males=55:35). All subjects had symptoms for at least 6 months, substantial restriction of shoulder mobility, and pain that required taking anti-inflammatory drugs. Calcium deposits were type I or type II and ranged from 1 cm to 3 cm in diameter. Subjects were divided into 3 groups to receive different energy levels of ESWT (E1=0.15 mJ/mm2, E2=0.44 mJ/mm2) or sham treatment. The number of pulses per session (n=1,500) was kept constant in groups E1 and E2. Anesthesia was not used in any of the protocols. In all groups, patients in each group received treatments at intervals of 6 weeks until symptoms had resolved, until 5 treatments had been applied, or until patients dropped out of the program. Group E1 (n=30) had significantly (t=7.77; p<0.001) less pain during ESWT (mean: 6.9±1.6, 10-point scale) than patients treated with the higher energy level E2 (mean: 9.6±1.0) as well as significantly (p<0.001) more treatments (mean: 4.1±0.8) than patients receiving the higher-energy protocol E2 (mean: 1.2±0.4). At 6-month follow-up, group E1 had residual calcification and recurrence of pain (87%). Subjects in group E2 (n=31) had no residual calcification or recurrence of pain. Sham treatment (n=29) had no effect. Adverse effects included a small number of hematomas (2 in E1, 6 in E2). ESWT in CT of the shoulder appears to be effective. It did not seem to have significant side effects at an energy level of E=0.44 mJ/mm2.
A meta-analysis performed by Louwerens, et al. (2014) assessed the short to midterm efficacy of minimally invasive treatments in the management of calcifying tendinopathy of the shoulder cuff.16 A systematic literature search identified 20 studies (1544 participants). The primary end points were identified as function, pain, and total resorption rates. Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) was used to assess the quality of evidence. Common methodological flaws were related to randomization. Studies showed there is moderate-quality GRADE evidence that high-energy ESWT has a significant effect on pain relief and functional status compared with other interventions.
Arirachakaran, et al. (2017) conducted a systematic review and meta-regression to compare clinical outcomes between treatments for CT, which included ESWT, ultrasound-guided percutaneous lavage (UGPL or barbotage), subacromial corticosteroid injection (SAI), and combined treatment.3 RCTs were identified using PubMed® and Scopus search engines, and 7 of 920 studies identified were eligible. Outcomes of interest were CM score, pain VAS, size of calcium deposit, and adverse effect. Results showed that ESWT significantly improved CM score and VAS when compared to placebo. Barbotage plus ESWT significantly improved CM score, VAS and decreased size of calcium deposit when compared to ESWT alone. Barbotage plus SAI significantly improved CM score and decreased size of calcium deposit when compared to SAI. No difference in adverse effects were found in all treatment groups. Multiple active treatment comparisons indicated that barbotage plus SAI significantly improved VAS and size of calcium deposit when compared to other groups, while barbotage plus SAI improved CM score when compared to other groups; however, there was no statistically significant difference. The network meta-analysis proposed that combined ultrasound (US)-guided needling and SAI significantly decreased shoulder pain VAS, improved CM score, and decreased the size of calcium deposits, while also lowering risks of adverse event when compared to barbotage plus ESWT or ESWT plus SAI. The authors concluded that the evidence suggests that UGPL is the treatment of choice for nonsurgical options of treatment in CT of the shoulder.
Another systematic review by Surace, et al. (2020) with broader inclusion criteria reported trends toward improvement in rotator cuff disease with ESWT but emphasized that all trials were susceptible to bias.18 The authors concluded that based upon the currently available low- to moderate-certainty evidence, there were very few clinically important benefits of ESWT, and uncertainty surrounding its safety. They highlighted that wide clinical diversity and varying treatment protocols suggests that there is uncertainty regarding whether some trials tested subtherapeutic doses, which could possibly underestimate any potential benefits. The authors recommended that a standard dose and treatment protocol be decided upon before further research is conducted. Development of a core set of outcomes for trials of rotator cuff disease and other shoulder disorders would help to facilitate the ability to synthesize the evidence.
Elbow tendinopathy:
Several treatments have been proposed to treat epicondylitis. Dingemanse, et al. (2014) conducted an evidence-based overview of the effectiveness of electrophysical modality treatments, including US, laser, electrotherapy, ESWT, transcutaneous electrical nerve stimulation (TENS) and pulsed electromagnetic field therapy, for both medial and lateral epicondylitis (LE).10
METHODS Searches were performed in PubMed®, EMBASE, CINAHL and Pedro to identify RCTs and systematic reviews. Two reviews and 20 RCTs evaluated the different electrophysical regimens for treatment of LE. Results demonstrated moderate evidence for the effectiveness of US vs. placebo on mid-term follow-up. US plus friction massage showed moderate evidence of effectiveness vs. laser therapy on short-term follow-up. Laser therapy showed moderate evidence of effectiveness vs. plyometric exercises on short-term follow-up. For all other modalities, including ESWT, studies showed only limited/conflicting evidence for effectiveness.
Buchbinder, et al. (2006) performed a systematic review of RCTs to determine the efficacy and safety of ESWT for treatment of lateral elbow pain.5 Nine placebo-controlled trials (n=1006) and 1 trial of ESWT vs. steroid injection (n=93) were included. The 9 placebo-controlled trials reported conflicting results. When available data were pooled, no significant benefit of ESWT over placebo could be found; weighted mean difference for improvement in pain (on a 100-point scale) from baseline to 4-6 weeks (pooled analysis of 3 trials, n=446) was -9.42 (95% CI -20.70 to 1.86). Two pooled results favored ESWT; relative risk of treatment success (at least 50% improvement in pain with resisted wrist extension at 12 weeks) in comparison to placebo (pooled analysis of 2 trials, 192 participants) was 2.2 (95% CI 1.55 to 3.12). However, this result was not supported by 4 other trials that were unable to be pooled. Steroid injection was determined to be more effective than ESWT at 3 months after the end of treatment assessed by a reduction of pain of 50% from baseline [21/25 (84%) vs. 29/48 (60%); p<0.05]. The authors concluded that ESWT provides negligible benefit in terms of pain and function in lateral elbow pain.
Vulpiani, et al. (2015) conducted a single-blinded RCT (n=80) comparing the effectiveness of ESWT (n=40) to cryoultrasound (n=40) in patients with chronic lateral epicondylitis over a 12-month period.22 Inclusion criteria were adults 18 to 75 years old, diagnosis of chronic lateral epicondylitis within at least 3 months, intensity of pain ≥ 5 on the VAS, and failure of previous conservative treatments. The primary outcome measure was a difference of 2 points in pain recorded on the VAS during the Cozen test for the ESWT group vs. the cryoultrasound group. The secondary outcome measure was the number of patients who achieved at least 50% satisfactory results, considered as the sum of excellent and good scores in the Roles and Maudsley score, at 3, 6 and 12 months of follow-up. Results showed that significant differences between groups for the VAS score were noted at 6 months (p<0.001) and 12 months (p<0.001) in favor of ESWT group. The satisfaction rate required at 50% was only achieved in the ESWT group in the follow-up at 6 (62.5%; p<0.003) and 12 (70.0%; p<0.001) months. Pain at the tolerability limit was reported by all of those treated with ESWT. The authors concluded that ESWT has better clinical therapeutic results at 6- and 12-month follow-up compared to cryoultrasound. However, limitations acknowledged for this study include the lack of a placebo group to demonstrate the natural course of the condition and absence of hand grip strength and finger pinch analysis. Additional investigation is needed for confirmation of the study results.
Yan, et al. (2019) conducted a meta-analysis (n=5 RCTs/233 patients) comparing the efficacy of ESWT and US in relieving pain and restoring the functions of tennis elbow following tendinopathy.23 The results showed a significantly lower VAS score of pain in the ESWT group at 1, 3, and 6 months (p=0.0001; p<0.00001; p<0.0001, respectively) compared to US. Additionally, the grip strength was significantly higher 3 months after ESWT (p<0.00001) than in the US group. No statistically significant difference was found in the scores of the elbow function after 3 months (p=0.13); however, the subjective scores of elbow functions were improved in the ESWT group (p=0.0008) compared to the US group. The authors concluded that ESWT offers more effective therapy for lateral epicondylitis than ultrasound therapy (UST). However, limitations of this study included small patient population, side effects of ESWT and US were not evaluated during follow-up, and the high heterogeneity among the results weakens. Longer studies are warranted to evaluate the efficacy of ESWT and US on tennis elbow function and to evaluate the optimal therapeutic setting of ESWT.
Carpal tunnel syndrome:
Kim, et al. (2019) conducted a systematic review and meta-analysis (n=6 RCTs/281 subjects) evaluating whether ESWT can improve symptoms, functional outcomes, and electrophysiologic parameters in CTS.13 RCTs were eligible for inclusion if there was at least 3 months of follow-up that described the effect of ESWT on CTS. Follow-up ranged from 12–24 weeks. ESWT showed significant overall effect size compared to the control (pooled standardized mean difference (SMD) = 1.447; 95% CI, 0.439-2.456; p=0.005). Symptoms, functional outcomes, and electrophysiologic parameters all improved with ESWT. However, no obvious difference between the efficacy of ESWT and local corticosteroid injection was found (pooled SMD = 0.418; 95% CI, -0.131-0.968; p=0.135). The authors concluded that ESWT appears to improve symptoms, functional outcomes, and electrophysiologic parameters in CTS; however, data on the long-term effects of ESWT are lacking and further research is needed to confirm the long-term effects and the optimal ESWT protocol for CTS. Limitations were noted to be small sample size and the patient population was limited to those with mild to moderate CTS. No studies aimed to investigate the effect of ESWT on severe CTS.
Other musculoskeletal conditions:
A RCT conducted by Carlisi, et al (2019) investigated whether ESWT is an efficacious in the treatment of GTPS.7 Patients (n=50) were randomized into the ESWT study group (n=26) or an UST control group (n=24). Patients in the ESWT group were treated with focused ESWT once weekly for 3 consecutive weeks. Patients in the control group were treated with UST daily for 10 consecutive days. The patients enrolled in the study met the following criteria: unilateral hip pain persisting for 6 weeks or longer; physical examination showed pain to palpation in the greater trochanteric area and pain with resisted hip abduction; gluteal tendinopathy, in the absence of full thickness tears; no corticosteroid injections or other conservative therapies (except pharmacological pain treatments), since the onset of the current pain episode; ESWT was not contraindicated; absence of clinical signs of lumbar radiculopathy on physical examination; no hip or knee osteoarthritis, no previous fractures or surgery in the affected limb, and no rheumatologic diseases. Outcomes measured hip pain and lower limb function using a numeric rating scale (p-NRS) and the Lower Extremity Functional Scale (LEFS scale), respectively. Patients were followed up at 2 months after the first treatment session and again 6 months later. Results showed a significant pain reduction over time for the study group and the control group, the ESWT proving to be significantly more effective than UST at the 2-month follow-up (2.08 vs. 3.36; p < 0.05) and at the 6 month follow-up (0.79 vs. 2.03; p < 0.05). A marked improvement of the LEFS total score was observed in both groups. Results showed no statistical differences between groups. The authors concluded that ESWT is effective in reducing pain in the short and mid-term; however, it does not appear to be superior to UST. Limitations were noted to include small patient population, short term follow-up, and unblinding of the patients.
Zelle, et al. (2010) performed a systematic review (n=11 studies/924 patients) for the use of ESWT in the treatment of fractures and delayed unions/nonunions.24 Eleven relevant studies met inclusion criteria (10 case series and 1 RCT). The overall union rate in patients with delayed union/nonunion was 76% (95% CI; 73%–79%) and ranged from 41% to 85%. Limitations included the paucity of higher-level evidence and comparative data. The authors concluded the ESWT seems to stimulate the healing process in delayed unions/nonunions; however, future studies need to investigate how ESWT compares with other treatment approaches and if different anatomic fracture locations may demonstrate different success rates. Also, the optimal treatment dose needs to be identified in further investigations. The authors also noted that the natural history of these lesions remains unclear, and it may be assumed that some delayed unions may have healed using other non-operative therapies.
Cacchio, et al. (2009) performed a double-blind RCT (n=126) comparing ESWT to surgery for the treatment of long bone nonunions.6 Patients were randomized either ESWT (Groups 1 and 2) or surgical treatment (Group 3). The patients in the ESWT groups received 4 treatments with 4000 impulses of shock waves with an EFD of 0.40 mJ/mm2 (Group 1) or 0.70 mJ/mm2 (Group 2). Radiographic results (the primary outcome) and clinical results (the secondary outcomes) were determined before and 3, 6, 12, and 24 months post-treatment. At 24 months, there were no significant differences found in clinical outcomes.
Alves, et al. (2009) conducted a systematic review (n=5 studies) of the evidence examining the use of ESWT for treatment of ONFH.2 Of the 5 studies, 2 were RCTs, 1 open label study, 1 comparative prospective study, and 1 was a case report. The review showed that there are no controlled and double-blind studies regarding the efficacy of ESWT in the treatment of ONFH. The noncontrolled studies appeared to demonstrate some favorable result, but the authors did note the lack of well-designed studies.
Chen, et al. (2009) investigated patient (n=17) functional outcomes of total hip arthroplasty (THA) for late ONFH in 1 hip and ESWT for early stages of ONFH in the opposite hip.8 Results showed that both THA and ESWT had significant improvements in pain score and Harris hip score (P<0.001). However, ESWT did appear to offer a significant difference in the magnitudes of improvement when compared to THA (P<0.001). Subjectively, patients rated ESWT better than THA in 13 cases (76.5%), ESWT comparable to THA in 4 cases (23.5%), and no patients rated THA better than ESWT. The authors concluded that short-term functional outcomes of hips treated with ESWT for early hip necrosis seem to be more favorable when compared to THA for late hip necrosis in patients with bilateral hip disease. It should be noted that before surgery, the THA side showed more pain and less function than the ESWT side (P<0.001). Limitations of the study included a small number of cases, short follow-up, non-blinded patient selection, and potential bias in clinical assessment given anticipation of more pain and disability in the THA side prior to surgery. Longer-term results are needed to validate the efficacy findings in this study.
ESWT has been proposed for other conditions, including PT. Thijs, et al. (2017) performed a RCT to evaluate the efficacy of a combined treatment of ESWT and eccentric training compared with sham-shockwave therapy (placebo) and eccentric training in patients with PT after 24 weeks.20 The authors found no significant differences for the primary and secondary outcome measures. Additional studies14,15,19 show low to moderate evidence for use of ESWT in the treatment of PT. These studies are also limited with small sample sizes and heterogeneity secondary to varying study designs and application protocols.