Extracorporeal shockwave therapy versus sham extracorporeal shockwave therapy for chronic Achilles tendinopathy: a meta-analysis of randomized controlled trials

Introduction

Chronic Achilles tendinopathy, defined as symptoms persisting over three months, is characterized by localized pain, morning stiffness, and functional impairment (Opdam et al., 2021; Van Dijk et al., 2011). It presents as either insertional (at the calcaneal attachment) or non-insertional (2–6 cm proximal to insertion), with distinct clinical characteristics (Chen et al., 2022). The condition affects 6% of the general population over a lifetime, but its prevalence rises significantly to 52% among endurance runners (Chen et al., 2024; Kujala, Sarna & Kaprio, 2005). It predominantly impacts middle-aged individuals engaged in sports, though sedentary populations with risk factors such as obesity and diabetes remain susceptible (Van der Vlist et al., 2019). Chronic Achilles tendinopathy significantly impacts quality of life, work productivity, and healthcare costs, with annual expenses averaging €840 per patient (Sleeswijk Visser et al., 2021). Additionally, 25%–60% of patients experience symptoms for 5–10 years (De Vos et al., 2021; Silbernagel, Hanlon & Sprague, 2020), making it a persistent and disabling condition that frequently drives clinical visits.

Conservative treatments for chronic Achilles tendinopathy mainly include activity modification, eccentric loading exercises, orthotic devices, non-steroidal anti-inflammatory drugs, and various physical therapy modalities (Chen et al., 2022; De Vos et al., 2021; Silbernagel, Hanlon & Sprague, 2020; Tarantino et al., 2023). However, these conventional treatments fail to achieve satisfactory results in about 25–45% of patients, often requiring additional interventions (De Vos et al., 2021; Silbernagel, Hanlon & Sprague, 2020). Furthermore, placebo effects have been widely documented in the conservative management of musculoskeletal conditions (Acosta-Olivo et al., 2020; Hafliðadóttir et al., 2021; Previtali et al., 2021), with a recent review (Viglione et al., 2023) reporting statistically and clinically significant placebo responses in the treatment of plantar fasciitis, especially in pain relief. This highlights a critical challenge in evaluating treatment effectiveness, particular for pain-related outcomes.

Extracorporeal Shockwave Therapy (ESWT) has emerged as a promising non-invasive treatment option for tendinopathy, involving the application of high-energy acoustic waves to affected tissues (Majidi et al., 2024). ESWT is theorized to stimulate tissue healing through multiple mechanisms, including neovascularization, enhanced blood supply, increased growth factor expression, anti-inflammatory effects, and stimulation of collagen synthesis (Poenaru, Sandulescu & Cinteza, 2023; Ryskalin et al., 2022; Simplicio et al., 2020). Two primary types of ESWT are utilized clinically: focused ESWT (fESWT), which delivers concentrated energy to deeper tissues, and radial ESWT (rESWT), which delivers more dispersed energy affecting larger, superficial areas (Auersperg & Trieb, 2020). The non-invasive nature of ESWT, coupled with its relatively low risk profile and potential to avoid surgery, has garnered significant clinical interest.

Despite its widespread adoption, evidence of ESWT’s effectiveness for chronic Achilles tendinopathy remains controversial. Previous systematic reviews and meta-analyses have reported inconsistent findings (Charles et al., 2023; Fan et al., 2020; Feeney, 2022; Paantjens et al., 2022; Stania et al., 2019). These discrepancies may stem from methodological heterogeneity, including variations in control groups (ranging from wait-and-see approaches to active therapies), treatment protocols, and outcome assessments. Additionally, concerns regarding potential adverse effects such as pain during application, local edema, erythema, and rare cases of tendon rupture warrant careful consideration (Majidi et al., 2024; Simplicio et al., 2020). Notably, previous reviews have compared ESWT to heterogeneous control interventions rather than specifically to sham treatments, making it challenging to distinguish true therapeutic effects from placebo responses. This represents a significant gap in the literature, as placebo effects are particularly relevant in pain-related conditions and subjective outcome measures.

This meta-analysis aims to assess the effectiveness and safety of ESWT compared exclusively to sham ESWT for chronic Achilles tendinopathy. By focusing on randomized controlled trials (RCTs) with sham controls, we seek to isolate ESWT’s specific therapeutic effect beyond placebo effects. Based on established minimal clinically important difference (MCID) thresholds (Challoumas et al., 2023; Murphy et al., 2018), we hypothesize that ESWT may demonstrate superior pain reduction, assessed by the Visual Analog Scale (VAS) with an MCID of 1.1 out of 10, and functional improvement, evaluated using the Victorian Institute of Sports Assessment-Achilles (VISA-A) score with an MCID of eight out of 100 and the American Orthopaedic Foot and Ankle Society (AOFAS) score with an MCID of 12 out of 100, while maintaining an acceptable safety profile compared to sham ESWT.

Materials & Methods

This meta-analysis adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines (Liberati et al., 2009) and was preregistered in the International Prospective Register of Systematic Reviews (PROSPERO) with the registration ID: CRD42025648082.

Results

Study selection and characteristics

A search of PubMed, EMBASE, the Cochrane Library, and Web of Science identified 241 studies. After removing 147 duplicates, 94 records underwent title and abstract screening. Of these, 62 were excluded, leaving 32 studies for full-text review. After reviewing the full texts, 24 studies were excluded (eight were not RCTs, 14 did not compare ESWT versus sham ESWT, and two were non-English studies), resulting in eight studies (Abdelkader et al., 2021; Alsulaimani et al., 2025; Costa et al., 2005; Gatz et al., 2021; Mansur et al., 2021; Pinitkwamdee et al., 2020; Rasmussen et al., 2008; Vahdatpour et al., 2018) being included in the final meta-analysis (Fig. 1).

Risk of bias

The methodological quality of the included studies was assessed using the RoB 2. Most studies showed a low risk of bias across the five domains, while some studies had an unclear risk in measurement of the outcome and missing outcome data. Specifically, two RCTs (Costa et al., 2005; Rasmussen et al., 2008) had an unclear risk in missing outcome data due to incomplete follow-up reporting, and one RCT (Gatz et al., 2021) had an unclear risk in measurement of the outcome due to patient-only blinding. The remaining RCTs were rated as low risk across all domains (Fig. 2).

Table 1:

Characteristics of the included studies.

First author	Year	Country	Sample size, n		Age, years Mean ± SD		Sex (M/F)		Symptom duration, months Mean ± SD (range)
			ESWT	Placebo	ESWT	Placebo	ESWT	Placebo	ESWT	Placebo
Costa	2005	UK	22	27	58.7 ± 10.8	47.7 ± 13.5	9/13	12/15	17.8 ± 10.1	20.8 ± 21.2
Rasmussen	2008	Denmark	24	24	49 ± 9	46 ± 13	12/12	8/16	3-12
Vahdatpour	2018	Iran	22	21	54.9 ± 11.3	54.3 ± 12.4	4/18	4/17	4.32 ± 1.55	4.51 ± 1.87
Pinitkwamdee	2020	Thailand	16	15	61.4 ± 5.9	56.5 ± 7.9	2/14	5/10	7.5 ± −(6–120)	12 ± −(6–48)
Abdelkader	2021	Egypt	25	25	29.9 ± 7.0	28.3 ± 6.8	22/28		6–12
Gatz	2021	Germany	21	21	43 ± 13.31	51 ± 10.36	15/6	13/8	24 ± 21.70	21 ± 23.79
Mansur	2021	Brazil	58	61	52.2 ± 10.9	53.5 ± 11.4	31/27	30/31	66.0 ± 96.7	76.2 ± 98.2
Alsulaimani	2025	Australia	38	38	48.5 ± 12.2	52.5 ± 11.1	19/19	17/21	33.3 ± 44.1	47.8 ± 71

DOI: 10.7717/peerj.20506/table-1

Notes:

M

male

F

female

NR

not reported

ESWT

extracorporeal shockwave therapy

UK

the United Kingdom

fESWT

focused extracorporeal shockwave therapy

rESWT

radial extracorporeal shockwave therapy

Table 2:

Details of ESWT and control group.

First author (Year)	ESWT type	Frequency (Hz)	Intensity (Energy)	Total shocks	Sessions (Interval, Duration)	Sham description	Blinding	Co-interventions
Costa et al. (2005)	fESWT –Electromagnetic, Storz Modulith SLK (4 mm focal area, US-guided)	NR	0.2 mJ/mm2	1,500	3 (1/month, 3 months)	Bubble wrap (opaque cloth) interposed for air gap; dissipates waves but mimics sounds/settings/positioning.	Double-blind (patients/assessors); no validation.	None during trial
Rasmussen et al. (2008)	rESWT - Piezoson 100 (to swelling/tenderness; no US)	50	0.12–0.51 mJ/mm2	2,000	4 (1/week, 4 weeks)	Same machine/probe/positioning/sounds at zero energy.	Double-blind (patients/evaluator); no validation.	Stretching + eccentric training (4 weeks).
Vahdatpour et al. (2018)	fESWT + rESWT - Duolith SD, Storz (reposition every 500 shocks)	3 (fESWT), 21 (rESWT)	0.25–0.4 mJ/mm2 (fESWT), 1.8-2.6 mJ/mm2 (rESWT)	1,500 (fESWT) + 3,000 (rESWT)	4 (1/week, 4 weeks)	Same positioning/machine sounds/probe movements at zero energy.	Double-blind (patients/evaluator); no validation.	Calf stretching + massage + eccentric training (4 weeks); diclofenac 100 mg/d (2 weeks).
Pinitkwamdee et al. (2020)	rESWT - Swiss DolorClast Classic (15 mm probe to tenderness ≤2 cm from insertion)	8–12	0.12–0.16 mJ/mm2	2,000	4 (1/week, 4 weeks)	Same blue radial probe/gel/settings/sounds but disconnected (red non-contact probe for sound only, no waves).	Double-blind (patients/assessor); validation: <50% correct guessing.	Avoid co-interventions/pain-provoking activities; rescue meds (naproxen 750 mg/d or acetaminophen 2,000–4,000 mg/d).
Abdelkader et al. (2021)	fESWT - DOULITH SD1, Storz (circumferential to max tenderness)	8	0.1 mJ/mm2	2,000	4 (1/week, 4 weeks)	Gel applied/handpiece moved identically at zero energy (same sounds/positioning).	Double-blind (patients/independent assessor); no validation.	Eccentric calf training (3 ×15 reps 2 ×/d, 7 d/wk, 4 weeks); stretching (3 ×30 s 2 ×/d, 7 d/wk, 4 weeks); avoid NSAIDs.
Gatz et al. (2021)	fESWT - Piezowave 2, Richard Wolf (gel pad; sliding on painful area; no US)	5	Mean 0.6 mJ/mm2	2,000 (+500 to calf)	4 (every 2 weeks, 6 weeks)	Same settings/sounds/positioning/gel pad but air-filled cavity blocks waves.	Single-blind (patients only); no validation.	Daily physiotherapy (24 weeks: eccentric 3 × 152 ×/d; stretching 1 ×/d; isometric 5 reps 1 ×/d); no sports (first 6 weeks).
Mansur et al. (2021)	rESWT - BLT600, BTL (to bulge/crease; prone)	7–10	1.5–2.5 bars	2000-3000	3 (every 2 weeks, 4 weeks)	Identical settings/positioning/protocol but firing transmission piece removed (no waves, same sounds).	Double-blind (patients/providers); validation: 85% patients/70% providers incorrect.	Eccentric exercises (modified Alfredson: 3 × 152 ×/d, 7 d/wk, 3 months); no sports (8 weeks).
Alsulaimani et al. (2025)	rESWT - Intellect RPW2, Chattanooga (to 3–4 cm2 painful insertion)	10	2–5 bars	3,000	3 (5–10 days apart, 10–20 days)	Identical device/noise/positioning/gel but pressure-minimizing component removed (no propagation, same auditory/tactile cues).	Double-blind (patients/independent assessor); validation: 81% patients incorrect.	Education; progressive isometric/eccentric calf raises (4 ×15, knee straight/bent, 3 ×/wk); paracetamol ≤4 g/d if needed; no other treatments/NSAIDs.

DOI: 10.7717/peerj.20506/table-2

Notes:

NR

not reported

ESWT

extracorporeal shockwave therapy

fESWT

focused extracorporeal shockwave therapy

rESWT

radial extracorporeal shockwave therapy

US

ultrasound

NSAID

non-steroidal anti-inflammatory drugs

VAS

At 1-month follow-up, six studies (Abdelkader et al., 2021; Alsulaimani et al., 2025; Mansur et al., 2021; Pinitkwamdee et al., 2020; Rasmussen et al., 2008; Vahdatpour et al., 2018) reported ΔVAS, showing no significant difference between the ESWT and sham ESWT groups (WMD, −0.39; 95% CI [−0.85 to 0.08]; I² = 0%; P = 0.10) (Fig. 3A).

At 3-month follow-up, six studies (Alsulaimani et al., 2025; Costa et al., 2005; Mansur et al., 2021; Pinitkwamdee et al., 2020; Rasmussen et al., 2008; Vahdatpour et al., 2018) reported ΔVAS, showing no significant difference between the groups, with a non-significant trend favoring ESWT (WMD, −0.56; 95% CI [−1.40 to 0.28]; I² = 64%; P = 0.19) (Fig. 3B).

At 6-month follow-up, two studies (Mansur et al., 2021; Pinitkwamdee et al., 2020) reported ΔVAS, showing no significant difference between the ESWT and sham ESWT groups (WMD, 0.14; 95% CI [−0.71 to 1.00]; I² = 0%; P = 0.74) (Fig. 3C).

At over 6-month follow-up, two studies (Abdelkader et al., 2021; Costa et al., 2005) reported ΔVAS, showing no significant difference between the groups, with a non-significant trend favoring ESWT (WMD, −0.61; 95% CI [−1.78 to 0.56]; I² = 0%; P = 0.31) (Fig. 3D).

VISA-A

At 1-month follow-up, three studies (Alsulaimani et al., 2025; Gatz et al., 2021; Mansur et al., 2021) reported ΔVISA-A scores, showing no significant difference between the ESWT and sham ESWT groups, with a non-significant trend favoring ESWT (WMD, 2.79; 95% CI [−5.27 to 10.86]; I² = 72%; P = 0.50) (Fig. 4A).

At 3-month follow-up, two studies (Alsulaimani et al., 2025; Mansur et al., 2021) reported Δ VISA-A scores, showing no significant difference between the groups, with a non-significant trend favoring ESWT (WMD, 3.90; 95% CI [−1.40 to 9.19]; I² = 37%; P = 0.15) (Fig. 4B).

At 6-month follow-up, two studies (Gatz et al., 2021; Mansur et al., 2021) reported ΔVISA-A scores, showing no significant difference between the ESWT and sham ESWT groups (WMD, 1.51; 95% CI [−4.13 to 7.14]; I² = 0%; P = 0.60) (Fig. 4C).

AOFAS

At 1-month follow-up, four studies (Gatz et al., 2021; Mansur et al., 2021; Rasmussen et al., 2008; Vahdatpour et al., 2018) reported Δ AOFAS scores, showing no significant difference between the ESWT and sham ESWT groups (WMD, 2.25; 95% CI [−0.60 to 5.11]; I² = 0%; P = 0.12) (Fig. 5A).

At 3-month follow-up, three studies (Mansur et al., 2021; Rasmussen et al., 2008; Vahdatpour et al., 2018) reported Δ AOFAS scores, showing no significant difference between the groups, with a non-significant trend favoring ESWT (WMD, 3.82; 95% CI [−5.02 to 12.65]; I² = 82%; P = 0.40) (Fig. 5B).

At 6-month follow-up, two studies (Gatz et al., 2021; Mansur et al., 2021) reported Δ AOFAS scores, showing no significant difference between the ESWT and sham ESWT groups (WMD, −0.08; 95% CI [−4.63 to 4.48]; I² = 0%; P = 0.97) (Fig. 5C).

Adverse events

Five studies (Alsulaimani et al., 2025; Costa et al., 2005; Mansur et al., 2021; Pinitkwamdee et al., 2020; Vahdatpour et al., 2018) reported adverse events, all of which were mild and did not require specific medical intervention. The ESWT group showed a higher incidence of adverse events (4.5%, 7/156) compared to the sham ESWT group (1.2%, 2/162). However, the difference between the groups was not statistically significant (OR, 2.89; 95% CI [0.75–11.04]; I² = 35%; P = 0.12) (Fig. 6).

Discussion

This meta-analysis included eight RCTs involving 458 patients comparing ESWT to sham ESWT for chronic Achilles tendinopathy. Primary findings, supported by low- to moderate-quality evidence, indicate that ESWT did not demonstrate superiority over sham ESWT. Pain reduction (ΔVAS) and functional improvement (ΔVISA-A and ΔAOFAS) revealed no significant differences at any follow-up. Although the ESWT group had a higher incidence of mild adverse events (4.5% versus 1.2% in the sham group), this difference was not statistically significant. Hypothesis-generating subgroup analyses based on ESWT type, tendinopathy classification, and symptom duration revealed statistically significant pain improvements only in patients with symptom duration <12 months, with sub-MCID improvement at 1-month (WMD: −0.76) and a clinically meaningful reduction at 3-months (WMD: −1.23) that exceeded the VAS MCID of 1.1 out of 10. Importantly, this benefit is transient and not robust, as it stems from exploratory subgroup analyses.

Previous systematic reviews and meta-analyses evaluating ESWT for Achilles tendinopathy have yielded varying conclusions (Charles et al., 2023; Fan et al., 2020; Feeney, 2022; Paantjens et al., 2022; Stania et al., 2019). A meta-analysis by Fan et al. (2020) reported that ESWT improves pain and function effectively, but included diverse control groups and non-RCTs, introducing heterogeneity and bias. Charles et al. (2023), Stania et al. (2019), and Paantjens et al. (2022) conducted broader reviews with mixed conclusions, but their heterogeneous control groups hindered the isolation of ESWT’s specific effectiveness. Feeney (2022) provided a narrative synthesis, concluding ESWT is at least as effective as other treatments, but lacking quantitative analysis and structured quality assessment.

Our study represents the first meta-analysis to exclusively compare ESWT with sham ESWT in chronic Achilles tendinopathy, thus isolating its specific effect by ensuring both groups received identical concomitant treatments. This rigorous approach across eight RCTs enhances evidence quality and reduces bias from variable co-interventions. Additionally, we evaluated multiple outcomes across structured time points, providing a more thorough analysis than prior studies. While previous reviews broadly concluded ESWT is effective for Achilles tendinopathy, our results suggest a more limited benefit, restricted to specific patient subsets.

Although our primary findings revealed no statistically significant differences overall, hypothesis-generating subgroup analyses indicated a transient benefit of ESWT in reducing pain (ΔVAS) among patients with symptom durations < 12 months. This included a statistically significant but subthreshold improvement at 1 month (WMD: −0.76), which fell short of the MCID of 1.1 points. In contrast, a clinically meaningful reduction at 3 months (WMD: −1.23) exceeded this threshold, suggesting a potential optimal early intervention window (Van der Worp et al., 2013). This temporal pattern likely reflects ESWT’s dose-dependent mechanisms (Abbas, Khan & Veqar, 2023; Ke et al., 2016; Yang et al., 2025), where mechanotransduction initiates healing through initial cellular responses and tissue repair, with sustained improvements in collagen remodeling developing over 1–3 months (Auersperg & Trieb, 2020; De la Corte-Rodríguez et al., 2023). Clinically, such early pain relief may enhance patient adherence without extended downtime, and reassessments at 3 months are recommended for subacute cases to capitalize on the tendon’s residual healing capacity, bridging reactive or dysrepair phases before degenerative progression (Majidi et al., 2024; Ryskalin et al., 2022; Simplicio et al., 2020). In contrast, diminished responsiveness in tendinopathy > 12 months likely stems from advanced degeneration (Lee et al., 2017), underscoring the need for phase-specific trials. However, these interpretations, remain preliminary given the limited evidence.

Hypothesis-generating subgroup analyses further explored ESWT types and Achilles tendinopathy subtypes but found no statistically significant differences. The effectiveness of focused versus radial ESWT remains debated: fESWT targets deeper tissues, potentially benefiting tendinopathy, while rESWT distributes energy more superficially (Auersperg & Trieb, 2020; van der Worp et al., 2013). Previous studies offer conflicting findings, with some favoring fESWT for deep-seated issues and others detecting no notable differences, highlighting the need for further research (Auersperg & Trieb, 2020; Şah et al., 2023). Non-insertional Achilles tendinopathy, prevalent among younger, active individuals, presented analytical challenges due to limited age-specific data. Theoretically, younger patients with healthier tendons and greater regenerative capacity may benefit more from ESWT, but current evidence is insufficient to confirm this (Pearce & Tan, 2016). Therefore, future studies should investigate these subgroups further.

In the sham-controlled design of this meta-analysis, placebo effects driven by patient expectations and contextual cues constitute an inevitable component. A systematic review of conservative treatments for plantar fasciitis explicitly quantified substantial placebo responses in sham ESWT cohorts (Viglione et al., 2023), emphasizing the need for rigorous evaluation of placebo effects. As outlined in Table 2, all eight RCTs employed targeted sham protocols designed to replicate authentic ESWT through measures such as zero-energy settings, disconnected probes, air-filled cavities, and interposed materials that dissipated waves while preserving auditory, positional, and tactile cues. Patient blinding was maintained across all trials, assessor blinding was achieved in seven trials, and formal validation of blinding success was reported in three trials, including less than 50% correct guessing in Pinitkwamdee et al. (2020), 85% of patients and 70% of providers providing incorrect guesses in Mansur et al. (2021), and 81% of patients providing incorrect guesses in Alsulaimani et al. (2025). Consequently, the overall risk of performance or detection bias arising from placebo effects in this synthesis remains reduced, supported by quantitative blinding validation, though minor uncertainties persist due to incomplete blinding validation in some studies.

Seven of the eight included RCTs incorporated co-interventions, primarily exercise protocols such as eccentric loading, stretching, and isometric training, applied equally to ESWT and sham arms. This balanced approach minimized confounding while aligning with evidence-based rehabilitation management of chronic Achilles tendinopathy. Evidence from the literature underscores that eccentric loading exercises, a cornerstone of rehabilitation, are supported by the highest level of evidence for improving tendon strength and reducing pain, particularly in early-stage tendinopathy (Silbernagel, Hanlon & Sprague, 2020). Stretching and isometric training further enhance tissue remodeling and pain management, contributing to a progressive loading program tailored to individual patient needs, as recommended for both midportion and insertional tendinopathy (Chen et al., 2022; Silbernagel, Hanlon & Sprague, 2020). A narrative review (Burton, 2022) of combined ESWT and exercise interventions for tendinopathy suggests potential synergy, with ESWT promoting tendon healing and exercise facilitating load-adaptive remodeling. However, it reports no consistent superiority of the combination over exercise alone across most tendinopathies. Clinical guidelines, including progressive loading protocols, advocate early rehabilitation with eccentric exercises, particularly for patients with symptom durations < 12 months, which aligns with our subgroup findings of transient pain relief (Silbernagel, Hanlon & Sprague, 2020). Therefore, the widespread use of co-interventions may mask ESWT’s isolated effects, contributing to the overall modest findings. Adding ESWT to standard rehabilitation involves notable costs ($300–$2,700 per course, depending on sessions and device), but the absence of economic data in the included studies precluded formal cost-effectiveness analysis. Future studies could incorporate such evaluations, including incremental cost-effectiveness ratios, alongside standardized protocols to refine ESWT-exercise integration for specific patient subgroups.

Given that statistically significant outcomes stem from hypothesis-generating subgroup analyses, our findings provide potential clinical insights rather than definitive medical recommendations. Patient selection seems critical, with individuals having symptom duration <12 months showing a higher likelihood of benefiting from ESWT. Early intervention may leverage the tendon’s residual healing mechanisms, potentially delaying progression to a chronic, degenerative state, though further investigation is warranted. The observed outcome variability highlights the need for standardized protocols, and the use of ESWT for non-insertional tendinopathy in younger, active individuals represents a promising underexplored area. These insights suggest that future studies could prioritize early intervention and tailored patient selection, such as for individuals with symptom duration <12 months. However, robust evidence from larger studies is needed to guide clinical decision-making.

This meta-analysis has several limitations. First, the small number of included studies and participants, coupled with limited representation of younger patients, restricts the strength of our conclusions. Second, although intergroup matching was maintained within individual studies, inter-study variations in patient demographics, ESWT parameters, and equipment may introduce heterogeneity that obscures the true effect of ESWT. Third, while co-interventions were standardized within each study’s groups, inconsistencies in their implementation across studies persist. Moreover, a prior review (Burton, 2022) indicated that combining exercises with ESWT is not consistently superior to exercises alone, which may confound the isolated impact of ESWT. Additionally, inconsistent reporting of activity levels, return-to-sport outcomes, and Achilles imaging across the studies precluded deeper analyses. Cost-effectiveness could not be evaluated due to the absence of economic data in the included trials. Furthermore, due to the limited number of studies and sample sizes, subgroup analyses comparing fESWT versus rESWT and non-insertional versus insertional chronic Achilles tendinopathy were highly constrained, preventing conclusions about outcome differences by modality or tendinopathy type. Finally, publication bias could not be formally assessed, as funnel plots and Egger’s test require at least ten studies per outcome for reliable interpretation.

Conclusions

Primary findings, supported by low- to moderate- evidence, indicate that in patients with chronic Achilles tendinopathy, ESWT and sham ESWT demonstrated comparable safety profiles and no significant differences in pain reduction or functional improvement across follow-up periods. Hypothesis-generating subgroup analyses revealed a transient pain-relieving benefit of ESWT in patients with symptom duration < 12 months, while no differences emerged by ESWT type or tendinopathy classification. Overall, these findings, limited by small sample sizes and protocol heterogeneity, should be interpreted cautiously.

Supplemental Information