The Immediate Clinical Effects Following a Single Radial Shock Wave Therapy in Pressure Ulcers: A Preliminary Randomized Controlled Trial of The SHOWN Project

Abstract

Objective:

Recent preliminary reports indicate that extracorporeal shock wave therapy (ESWT) might be useful for chronic wounds, especially venous leg ulcers and diabetic foot ulcers. However, there is limited evidence for the utility and safety of ESWT in pressure ulcers (PUs). Therefore, this randomized controlled trial (RCT) aimed to assess immediate planimetric and clinical effects following a single radial ESWT session in PUs.

Approach:

A group of 40 patients with PUs was randomly assigned into 2 groups: active ESWT (n = 20), which underwent a single treatment with radial ESWT (300 + 100 impulses/1 cm², 2.5 bars, 0.15 mJ/mm², and 5 Hz) and placebo ESWT (n = 20), which was exposed to sham-radial ESWT. All patients continued standard wound care procedures. The planimetric assessment and clinical outcomes using Wound Bed Score (WBS) and Bates–Jansen Wound Assessment Tool (BWAT) were assessed before (M0) and after ESWT sessions (M1).

Results:

There was a significant planimetric enhancement observed after active ESWT reported as a reduction in all metric parameters: wound area from 11.51 to 8.09 cm² (p < 0.001), wound length from 4.97 to 4.41 cm (p < 0.001), and wound width from 3.15 to 2.49 cm (p < 0.0001). Also, there was a significant beneficial clinical improvement observed with a WBS as an increased score from 3.85 to 9.65 points (p < 0.001) and with the BWAT as a decreased score from 45.45 to 30.70 points (p < 0.001). In turn, a regression in the placebo ESWT group was observed in all studied outcomes.

Innovation:

This study is the first RCT to provide the positive and immediate clinical effects of radial ESWT in promoting the healing of PUs.

Conclusion:

This preliminary RCT showed that even a single session of ESWT is a promising and clinically effective modality in managing PUs. However, there is still limited data regarding the usefulness of ESWT in PUs, and further studies are in demand.

Robert Dymarek, PhD

INTRODUCTION

Chronic wounds affect millions of people globally, and the annual incidence rate is growing; thus, they constitute a real challenge to wound care providers.^1,2 Nowadays, chronic wounds will be an increasing worldwide problem in the care of older adults due to the successive aging of the population.³ The fact is that the effective treatment of hard-to-heal wounds and related complications is still a holistic and multidisciplinary medical issue.⁴

Chronic wounds are defined as those that have not progressed through a repair process to achieve structural and functional integrity within 3 months or that have progressed through the repair process without establishing a persistent anatomic and functional outcome.⁵ Chronic wounds fail to heal and are characterized by severe disturbances as well as being unresponsive to conventional long-term treatment. Wound healing is a complex process where four consecutive phases can be differentiated, that is, hemostasis, inflammation, proliferation, and remodeling.⁶ The most typical chronic soft tissue wounds are venous leg ulcers (VLUs), arterial ulcers, diabetic foot ulcers (DFUs), and pressure ulcers (PUs) or those with mixed etiology.⁷

It is estimated that 60–70% of all detected PUs are found in people over 65–70 years of age, with particular concentration in patients newly admitted to the geriatric ward, where the incidence of PUs is in the range of 8–20%.⁸ Generally, it is hard to predict rates of prevalence and incidence; however, the prevalence of PUs varies, depending on sources, between 7% and 25% of hospitalized patients.⁹ Recent data indicate a wide range in the prevalence of PUs among hospitalized patients: 3.1–30.0% in the United States, 1.0–54.0% in Europe, 6.0% in Australia, and 2.7–16.8% in Asia.¹⁰ The suffering of patients with PUs and the relationship with increased mortality has been documented.¹¹ PUs are the most expensive chronic wounds in terms of their treatment costs and significant burden on the health care systems.¹²

The primary goal in the evidence-based management of chronic wounds is to promote effective tissue granulation and re-epithelialization and achieve complete wound closure. Reducing internal (diabetes, smoking, malnutrition, immunosuppression, vascular disease, spinal cord injury, contractures, prolonged immobility) and external risk factors (lying on hard surfaces, nursing homes, poorly fitting prostheses, poor skin hygiene, patient restraints), as well as complications, which can lead to deterioration of the wound, are also crucial.¹³

It should also be remembered that several critical parameters, including the anatomical location of the wound and complications due to comorbidities that patients may have, especially in PUs, affect the complexity and level of challenge of chronic wounds.¹⁴ Complex wound care modalities, considered the gold standard for treating soft tissue wounds, can be successfully supported and promoted by various modern biophysical methods.^15,16

The effectiveness and safety of particular physical agents, such as electrical stimulation (ES) or ultrasound therapy (UT) are well documented.¹⁷ Findings from randomized controlled trials (RCTs) prove that ES in the form of high-voltage pulsed current and treatment sessions with UT can be an adjuvant treatment method in chronic wounds.¹⁸ Regarding the clinical utility of low-level laser therapy, insufficient preliminary findings indicate that well-designed studies are still needed.¹⁹ Moreover, further clinical trials evaluating the healing progression of chronic wounds are required for all the technologies mentioned above, especially concerning antibacterial effects.²⁰ It should be noted that the popularity of extracorporeal shock wave therapy (ESWT) for the treatment of chronic wounds is growing.

ESWT is defined as a sequence of single short-period acoustic pulses with high peak pressure and rapid propagation in three-dimensional space that generate transient pressure disturbance and are applied directly to tissues without persistent damage.²¹ There are two types of ESWT differing in the type of generators, biophysical properties, treatment parameters, beam shape, peak energy, and depth of propagation into tissues: focused and radial ESWT. Focused ESWT is generated by electromagnetic, electrohydraulic, and piezoelectric devices; the pressure energy increases rapidly in the range of 10–100 MPa and focuses a beam of acoustic energy with a penetration depth of up to about 12 cm. In contrast, radial ESWT is generated by pneumatic (ballistic) devices; the pressure energy increases slower, peaking to lower levels in the range of 0.1–1 MPa; the energy spreads in a wider beam over a larger target area and is absorbed to a depth of about 3 cm.²²

Currently, there are advanced studies on the mechanisms of biological action of ESWT underlying the wound healing process.^23

–27 Supporting basic science evidence for soft tissue wound healing is also available. Preclinical experiments on animal models illustrate that ESWT can promote favorable molecular and immunochemical reactions resulting in improvement of blood flow microcirculation,²² promotion of angiogenesis and neovascularization,²³ enhancement of cell proliferation,²⁴ activations of anti-inflammatory response,²⁵ and stimulation of tissue repair and regeneration.²⁶

Also, in vitro exposure of cells to ESWT can influence their proliferation, differentiation, gene expression, production of growth factors, and release of cytokines.^27

–30 Other studies have hypothesized that ESWT covers mechanical stimulus into biological response inducing molecular changes through mechanotransduction, which modulates endothelial cell physiology through intracellular and extracellular signaling pathways.^31

–34 ESWT activates numerous cellular reactions, which regulate and stimulate their function and metabolism.^31,35

Recent clinical studies demonstrate the successful effects of using ESWT in managing chronic wounds.^36,37 Based on a critical review of the current literature with the use of international database search engines, such as PubMed, Scopus, EBSCOhost, and PEDro, it was found that, to date, there is a relatively low number of reports investigating the use of ESWT in the treatment of soft tissue wounds. Most articles published with the RCT protocol involved DFUs,^38

–44 and the vast minority involved VLUs⁴⁵ and PUs.⁴⁶ Moreover, all of these studies used focused or defocused ESWT as an experimental intervention. The summary of the results of recent studies is presented in Table 1.

Table 1.

Summary of the results of recent studies on extracorporeal shock wave therapy in chronic wounds

Authors, Year Journal	Study Design	Patients	Wounds	Intervention	Outcomes
Larking et al 2010⁴⁶ Clinical Rehabilitation	Double RCT Crossover	n = 9 4 men 5 women 63 years old	Pus Average duration = 54 weeks	fESWT np = 200 + 100/cm² EFD = 0.1 mJ/mm² p = n/s f = 5 Hz 1/week for 4 weeks	Improved healing starting 6–8 weeks after the ESWT start, whether treated first with the placebo or the active ESWT
Porso et al 2017⁴⁹ Ultrasound in Medicine and Biology	PCT Pilot study	n = 10 4 men 6 women 65 years old	ALU = 1 DFU = 1 MIX = 4 PTR = 1 VLU = 3 Average duration = 10 months	dESWT np = 300 + 100/cm² EFD = 0.15 mJ/mm² p = n/s f = 4 Hz 1/week for 3 weeks	A significant reduction in wound size and BWAT and VAS values from before and to 90 days after ESWT was observed; 7/10 wounds healed completely and 9/10 patients reported complete pain relief
Saggini et al 2008⁵⁰ Ultrasound in Medicine and Biology	CCS	n = 30 18 men 12 women 58 years old	VLU = 12 PTR = 16 DFU = 4 Average duration = 5.3 months	fESWT np = 100/cm² EFD = 0.037 mJ/mm² P = n/s f = 4 Hz	16 wounds healed completely within 6 sessions of ESWT; in all of the nonhealed wounds, decrease of the number of exudates, increased percentage of granulation tissue compared with fibrin/necrotic tissue and decrease of wound size was statistically significant after 4–6 sessions of ESWT; significant decrease of pain was reported
Schaden et al 2007⁵¹ Journal of Surgical Research	PCT Feasibility study	n = 208 109 men 99 women 61 years old	DH = 82 PTR = 67 VLU = 25 PU = 21 ALU = 6 BW = 7 Average duration = 10 months	fESWT np = 100–1,000/cm² EFD = 0.1 mJ/mm² p = n/s f = 5 Hz 1–2/week	156 wounds had 100% wound epithelialization; during mean follow-up period of 44 days, there was no ESTW-related toxicity, infection, or deterioration of treated wound
Wolff et al 2011⁵² Ultrasound in Medicine and Biology	PCT Midterm results	n = 228 140 men 88 women 63 years old	PSU = 93 PTR = 86 VLU = 38 PU = 13 ALU = 11 CP = 9 BW = 8 Average duration = 4–12 weeks	dESWT np = 100–300/cm² EFD = 0.1 mJ/mm² p = n/s f = 5 Hz Median duration of therapy: 2 weeks	Wound closure occurred in 191 patients (74.03%) by a median of 2 ESWT treatment sessions; no wound reappeared at the same location; a median positive difference between the initial WBS and the final WBS scores of 14 was observed
Duan et al 2020⁴⁷ Medicine	CR	n = 1 men 62 years old	PU Average duration = 2 weeks	rESWT np = 200/300 + 100/cm² EFD = n/s p = 2–3 bar f = 4–5 Hz 1/week for 12 weeks	After ESWT sessions, the PUSH scores were 17 points, 13 points, 9 points, and 5 points, as well as 0 points, respectively, before treatment and at the 4-, 8-, and 12-week follow-ups as well as at 2 weeks after discharge
Kang et al 2020⁴⁸ American Journal of Translational Research	CR	n = 1 men 51 years old	PU Average duration = 3 weeks	rESWT np = 3,000–6,000 EFD = n/s p = 2–3.5 bar f = 10 Hz 2/week for 3 months	The application of ESWT to a surgically debrided PU on the heel resulted in complete healing of the wound after 3 months

ALU, arterial leg ulcer; BW, burn wound; BWAT, Bates–Jansen Wound Assessment Tool; CP, cast pressure; CR, case report; CSS, controlled case series; dESWT, defocused ESWT; DFU, diabetic foot ulcer; DH, disturbed healing; EFD, energy flux density; ESWT, extracorporeal shock wave therapy; fESWT, focused ESWT; MIX, mixed etiology; n/s, not specified; np, number of shock wave pulses; PCT, prospective clinical trial; PSU, postsurgical; PTR, post-traumatic; PU, pressure ulcer; PUSH, pressure ulcer scale for healing; RCT, randomized controlled trial; rESWT, radial ESWT; VAS, visual analog scale; VLU, venous leg ulcer; WBS, wound bed score.

Therefore, the main objective of this preliminary RCT was to assess the immediate changes after radial ESWT, considering planimetric assessment and clinical evaluation, as well as to compare the outcomes between active and placebo ESWT.

CLINICAL PROBLEM ADDRESSED

So far, there is only one 12-year-old study by Larking et al,⁴⁶ who allocated only nine patients in their crossover RCT. Also, two current case report studies published in 2020 can be found that demonstrate the effect of ESWT in PUs, first by Duan et al⁴⁷ about sacroiliac PU necrosis and second by Kang et al⁴⁸ regarding heel PU after spinal cord injury.

Also, there are a few articles presenting results of ESWT in various chronic or acute wounds.^49

–52 Nevertheless, only two studies by Schaden et al⁵¹ and Wolff et al⁵² were conducted among patients with PUs (n = 13 and n = 14, respectively). Moreover, most of these studies have a preliminary character and used typical focused or defocused ESWT transducers. Finally, it should be noted that only the above case reports by Duan et al⁴⁷ and Kang et al⁴⁸ used radial ESWT transducer.

There is limited evidence on studies assessing the radial type of ESWT in chronic wounds, especially involving patients with PUs. Therefore, this subject remains understudied, and it might even be neglected in the case of PUs. It should be emphasized that radial ESWT is generated by pneumatic devices, which are less expensive, and the radial stimulus is noninvasive due to the lower peak pressure delivered to the tissues during the therapeutic procedure.

MATERIALS AND METHODS

Study design

This preliminary, prospective, double-blinded RCT was conducted in an inpatient long-term care center and an outpatient specialist wound care clinic in Wroclaw, Poland. The study was performed between January 2017 and October 2021. The standards for Consolidated Standards of Reporting Trials (CONSORT) were followed. In addition, the study project was prospectively registered with the trial acronym SHOWN (SHOck Waves in wouNds) at the Clinical Trials Registry Platform (No. ACTRN12617000075381).

Ethical considerations

The study protocol was approved by the Bioethics Committee of the Wroclaw Medical University, Poland (Approval No. KB-632/2016). Informed consent was obtained from all participants included in this study. The participants were informed that they were allowed to withdraw at any study stage. The study was carried out according to the Declaration of Helsinki and Good Clinical Practice guidelines.

Selection criteria

All the patients were qualified based on well-defined inclusion and exclusion criteria. Factors, such as gender, race, age, and wound location, did not affect the eligibility. The inclusion criteria were: (1) a diagnosed chronic wound of PU etiology, (2) a wound duration longer than 3 months, (3) a wound classified as grade I (full-thickness skin damage) or grade III (subcutaneous tissue damage with minor necrosis) according to EPUAP classification,⁵³ (4) the lack of contraindications to ESWT interventions (cancer and tumors, blood coagulation disorders, acute inflammation, pacemaker, and electronic implants were also excluded from the study), and (5) obtaining the patient's voluntary and informed consent to participate in the study.

In turn, the exclusion criteria comprised: (1) clinically confirmed bacterial wound infection, (2) a wound classified as grade I (fading redness of the skin), or grade IV (advanced necrosis reaching to the muscles and bones) according to EPUAP classification,⁵³ (3) wound that requires urgent surgical intervention, (4) the lack of patients' consent to participate in the study, and (5) noncompliance with the study protocol.

Study population

At the enrollment stage, the study group consisted of 62 patients; however, 22 patients were excluded from participation in the study at the selection stage due to exclusion criteria (n = 19), decline to participate in the study (n = 1), and death during the study (n = 2). Finally, 40 patients were enrolled in the study and randomly allocated into 2 comparative groups. All patients finished the study and were analyzed. A detailed general and clinical characteristics of study participants are presented in Tables 1 and 2, respectively.

Table 2.

General characteristics of the study participants

Variables	Active ESWT (n = 20)	Placebo ESWT (n = 20)	p
Sex, n (%)
Male	2 (10.0)	5 (25.0)	0.210^a
Female	18 (90.0)	15 (75.0)	0.210^a
Age, years
M ± SD	84.80 ± 8.98	84.05 ± 9.14	0.680^b
Me (Q1 to Q3)	88.00 (83.50 to 90.50)	86.50 (85.00 to 89.00)
Min to Max	61.00 to 92.00	62.00 to 92.00
Body height, m
M ± SD	1.67 ± 0.09	1.68 ± 0.08	0.870^b
Me (Q1 to Q3)	1.67 (1.61 to 1.71)	1.64 (1.63 to 1.72)
Min to Max	1.54 to 1.83	1.58 to 1.85
Body weight, kg
M ± SD	65.98 ± 14.30	69.81 ± 12.12	0.370^c
Me (Q1 to Q3)	65.20 (51.60 to 80.00)	71.50 (62.40 to 81.00)
Min to Max	45.00 to 87.00	48.00 to 92.00
BMI, kg/m²
M ± SD	23.43 ± 3.85	24.71 ± 3.84	0.260^b
Me (Q1 to Q3)	22.42 (20.46 to 25.90)	24.18 (21.34 to 28.58)
Min to Max	17.80 to 31.20	19.23 to 30.12

χ² test.

Mann–Whitney U test.

t-Test for independent sample.

BMI, body mass index; M, mean; Max, maximum; Me, median; Min, minimum; n, number of participants; Q1, lower quartile (25%); Q3, upper quartile (75%); SD, standard deviation.

Randomization procedure

A final group of 40 patients with diagnosed PUs met the inclusion criteria and were included in the study. All patients were randomly assigned to the intervention and received an active radial ESWT (n = 20) or sham-placebo radial ESWT (n = 20) using a website-generated randomization tool. All patients were blinded to their radial ESWT intervention, and only the researcher performing the shock wave intervention knew the type of intervention, active or placebo. The same researcher–physiotherapist, experienced in the physical management of chronic wounds, performed all radial ESWT sessions in both groups. Figure 1 shows the study flow chart of study participants according to the CONSORT guidelines.

Figure 1.

Flow chart of study participants according to the CONSORT guidelines. CONSORT, Consolidated Standards of Reporting Trials; ESWT, extracorporeal shock wave therapy.

Treatment procedure

All enrolled patients underwent a single intervention using a radial ESWT transducer (Cellactor^® SC1; Storz Medical, AG, Tägerwilen, Switzerland). In the active ESWT group, treatment shockwave parameters included: the number of pulses of 300 at baseline +100 per cm², the pressure of 2.5 bars, and the energy flux density of 0.15 mJ/mm², and frequency of 5 Hz. In the passive sham ESWT group, the same device and shockwave parameters were applied; however, a special polyethylene covering filled with a depreciation sponge was placed directly on the transducer to absorb ESWT energy and assure placebo ESWT conditions.⁵⁴

It should be noted that all patients continued their comprehensive standard wound care procedure, including individually selected specialist dressings,¹³ and wound debridement according to best international practices and recommended guidelines⁵⁵ as well as patient positioning and relief pressure methods using antidecubitus mattresses with compressors.

Outcome measures

In the present preliminary study, we have paid attention to clinical effects, including planimetric measures using a novel medical application and clinimetric assessments using dedicated tools: Wound Bed Score (WBS) Bates–Jansen Wound Assessment Tool (BWAT). Considering assessments of short-term effects, we assumed two measurement time points, immediately before (M0, baseline) and 1 week after radial ESWT sessions (M1, final).

Planimetric assessment

The planimetric smartphone application Swift Skin and Wound Mobile App (Swift Medical, Canada) was used to perform an objective assessment according to the changes in wound metric parameters. The application is a medical device for imaging and documenting the progression of wound healing. It was proved that this technology is highly reliable and accurate for noncontact and easy-to-use wound measurements.⁵⁶ The measurements have negligible error <0.5% and low 2–5% variability. The iPhone 7 Plus device running iOS version 12.2 was used for this study.

Clinical assessment

The WBS is a validated tool for the clinical assessment of chronic wounds. It consists of eight items denoted by the acronym BEDSCORE, where the following clinical wound parameters are assessed: B—black eschar, E—eczema or dermatitis, D—depth, S—scaring, C—color, O—edema or swelling, R—resurfacing epithelium, and E—exudate amount. Each item is scored in 0–2 points, and the total score range is 0–16 points. The interpretation of the WBS tool indicates that the higher the score, the better the clinical wound condition. The WBS can be useful in both research and clinical practice to provide optimized treatments and study new treatment possibilities.⁵⁷

The BWAT is a standardized tool consisting of 13 items. The wound parameters are evaluated in the following order: 1—size, 2—depth, 3—edges, 4—undermining, 5—a type of necrotic tissue, 6—the amount of necrotic tissue, 7—exudate type, 8—exudate amount, 9—skin color around the wound, 10—peripheral tissue edema, 11—tissue sclerosis around the wound, 12—granulation tissue, and 13—epithelialization. The score range for items 1–9 is 1–5 points, and for the remaining items, 10–13 is 0–5 points. The range of total score for BWAT is 9–65 points. The interpretation of the BWAT tool indicates that the lower score, the better the clinical wound condition. The BWAT presents moderate-to-high reliability.⁵⁸

Statistical analysis

Statistical analysis was performed using Statistica 13 software (TIBCO, Software, Inc.). Arithmetic means, medians, quartiles, standard deviations, and range of variation (extreme values) were calculated for quantitative variables. For qualitative variables, frequencies of occurrence (percentages) were calculated.

All quantitative variables were tested with the Shapiro–Wilk test to determine the type of distribution. A comparison of qualitative variables between groups was made using the chi-square (χ²) test. A comparison of the results of quantitative type variables between the study group and placebo group was performed using the t-test for independent samples or the Mann–Whitney U test, depending on whether the test's assumptions were met. Finally, a comparison of pre- and post-ESWT intervention outcomes in each group was performed using the parametric t-test for dependent samples or the nonparametric Wilcoxon test, depending on whether the test's assumptions were met. The values for p < 0.05 were taken as statistically significant.

RESULTS

Population characteristics

The final sample included 40 patients with Pus, including 7 males and 33 females with mean age of 84.43 ± 8.95 years (range: 61.0–92.0), mean height of 1.68 ± 0.08 m (range: 1.54–1.85), mean weight of 67.9 ± 13.23 kg (range: 45.0–92.0), and mean body mass index of 24.07 ± 3.85 kg/m² (range: 17.80–31.20). The mean duration of PUs was 5.52 ± 3.07 months (range: 3.0–16.0). The present study included PUs in different anatomical locations, including the following areas: sacral (n = 19), calcaneal (n = 6), trochanteric (n = 5), malleolar (n = 4), calf (n = 4), buttock (n = 1), and ischial (n = 1). A detailed characteristic of study participants in each study group presents Table 2 in terms of general anthropometric information and Table 3 in terms of clinical characteristics. The studied groups were homogeneous regarding their general and clinical baseline characteristics (p > 0.05).

Table 3.

Clinical characteristics of the study participants

Variables	Active ESWT (n = 20)	Placebo ESWT (n = 20)	p
Duration, months
M ± SD	5.80 ± 3.32	5.25 ± 2.86	0.590^a
Me (Q1 to Q3)	5.00 (3.00 to 8.00)	4.00 (3.00 to 7.50)
Min to Max	3.00 to 16.00	3.00 to 14.00
Side, n (%)
Left	7 (35.0)	7 (35.0)	0.910^b
Central	9 (45.0)	10 (50.0)
Right	4 (20.0)	3 (15.0)
Location, n (%)
Sacral	9 (45)	10 (50)	0.430^b
Calcaneal	5 (25)	1 (5)
Trochanteric	3 (15)	2 (10)
Malleolar	2 (10)	2 (10)
Calf	1 (5)	3 (15)
Buttock	0 (0)	1 (5)
Ischial	0 (0)	1 (5)
Comorbidities, n (%)
HT	13 (65.0)	15 (75.0)	0.490^b
AO	13 (65.0)	13 (65.0)	1.000^b
CVI	2 (10.0)	1 (5.0)	0.55^b
DM	2 (10.0)	2 (10.0)	1.000^b

Mann–Whitney U test.

χ² test.

AO, arteriosclerosis obliterans; CVI, chronic venous insufficiency; DM, diabetes mellitus; HT, hypertension.

Planimetric assessment

An improvement in planimetric assessment was observed after a single session of active radial ESTW. However, all studied planimetric parameters of the PUs were decreased regarding comparisons between M0 versus M1, including the area from 11.51 ± 9.61 to 8.09 ± 7.96 (p < 0.001), length from 4.97 ± 2.96 to 4.41 ± 3.19 (p < 0.001), and width from 3.15 ± 1.83 to 2.49 ± 1.66 (p < 0.0001). In turn, the placebo ESWT group has noted a deterioration, which was statistically significant, including area (p = 0.002) and width (p = 0.005).

Also, intergroup comparisons revealed statistically significant planimetric changes in favor of the group treated with active ESWT than those treated with placebo ESWT in terms of differences between M1 and M0 measurements regarding all studied planimetric parameters: area −3.42 ± 2.66 versus 1.09 ± 1.19 (p < 0.001), length −0.57 ± 0.41 versus 0.11 ± 0.38 (p < 0.001), and width −0.66 ± −0.25 versus 0.25 ± 0.35 (p < 0.001), respectively. A detailed presentation of the planimetric results is shown in Table 4.

Table 4.

Basic statistics of wound planimetric parameters before and after extracorporeal shock wave treatment

	M0	M1	ΔM = M1 − M0	p ^a
Active ESWT
Area, cm²
M ± SD	11.51 ± 9.61	8.09 ± 7.96	−3.42 ± 2.66	<0.001^c
Me (Q1 to Q3)	5.25 (4.00 to 22.90)	3.75 (2.15 to 17.20)	−2.30 (4.90 to −1.80)
Min to Max	3.20 to 29.10	1.00 to 22.90	−10.70 to −0.40
Length, cm
M ± SD	4.97 ± 2.96	4.41 ± 3.19	−0.57 ± 0.41	<0.001^c
Me (Q1 to Q3)	3.50 (2.75 to 6.30)	2.85 (2.05 to 6.00)	−0.60 (−0.90 to −0.20)
Min to Max	2.50 to 12.40	1.60 to 12.10	−1.10 to 0.20
Width, cm
M ± SD	3.15 ± 1.83	2.49 ± 1.66	−0.66 ± −0.25	<0.0001^c
Me (Q1 to Q3)	2.20 (1.80 to 4.75)	1.70 (1.40 to 3.60)	−0.65 (−1.00 to −0.25)
Min to Max	1.20 to 6.90	0.80 to 6.10	−1.70 to 0.20
Placebo ESWT
Area, cm²
M ± SD	12.32 ± 12.54	13.40 ± 13.28	1.09 ± 1.19	0.002^c
Me (Q1 to Q3)	8.95 (3.30 to 15.60)	9.10 (3.60 to 17.45)	0.75 (0.25 to 1.95)
Min to Max	1.80 to 42.50	2.50 to 44.20	−1.30 to 3.40
Length, cm
M ± SD	4.61 ± 2.37	4.73 ± 2.22	0.11 ± 0.38	0.16^c
Me (Q1 to Q3)	4.55 (2.40 to 6.25)	4.45 (2.65 to 6.50)	0.15 (−0.20 to 0.35)
Min to Max	1.80 to 8.90	2.10 to 8.70	−0.70 to 0.80
Width, cm
M ± SD	3.01 ± 1.74	3.26 ± 1.86	0.25 ± 0.35	0.005^c
Me (Q1 to Q3)	2.25 (1.80 to 3.60)	2.65 (1.90 to 3.80)	0.15 (0.00 to 0.40)
Min to Max	1.40 to 7.00	1.70 to 7.60	−0.20 to 1.10
p-Value area^d	0.59^e	0.07^e	<0.001^b,e
p-Value length^d	0.56^e	0.23^e	<0.001^b,f
p-Value width^d	0.90^e	0.022^e	<0.001^b,f

M0 versus M1.

M1 − M0.

Wilcoxon signed-rank test.

Active ESWT versus placebo ESWT.

Mann–Whitney U test.

t-Test for unpaired samples.

M0, measurement before ESWT; M1, measurement after ESWT; ΔM = M1 − M0, difference between before and after ESW.

ESW, extracorporeal shock wave.

Clinical evaluation

A beneficial clinical change was reported after a single active radial ESWT session. Both studied evaluations using clinical tools showed improvement regarding comparisons between M0 versus M1, including WBS from 3.85 ± 2.78 to 9.65 ± 3.82 (p < 0.001) and BWAT from 45.45 ± 8.65 to 30.70 ± 7.89 (p < 0.001). In turn, PUs in the placebo ESWT group were noted to worsen, including WBS and BWAT scores.

Also, intergroup comparisons revealed statistically significant clinical changes in favor of patients treated with active ESWT than those treated with placebo ESWT in terms of differences between M1-M0. For the WBS tool, it was 5.80 ± 3.09 points in the active ESWT versus 0.00 ± 3.99 points in the placebo ESWT (p < 0.001). For the BWAT tool, it was −14.75 ± 6.54 points in the active ESWT versus 1.35 ± 5.79 points in the placebo ESWT (p < 0.001). A detailed presentation of the clinical results is shown in Table 5.

Table 5.

Basic statistics of wound clinical assessment before and after extracorporeal shock wave treatment

	M0	M1	ΔM = M1 − M0	p ^a
Active ESWT
WBS (points)
M ± SD	3.85 ± 2.78	9.65 ± 3.82	5.80 ± 3.09	<0.001^c
Me (Q1 to Q3)	3.00 (2.00 to 6.00)	9.50 (7.00 to 12.50)	5.00 (3.00 to 9.00)
Min to Max	1.00 to 10.00	2.00 to 15.00	1.00 to 11.00
BWAT (points)
M ± SD	45.45 ± 8.65	30.70 ± 7.89	−14.75 ± 6.54	<0.001^d
Me (Q1 to Q3)	47.00 (38.50 to 52.00)	29.00 (24.00 to 37.00)	−14.00 (−19.00 to −9.00)
Min to Max	31.00 to 60.00	20.00 to 47.00	−30.00 to −5.00
Placebo ESWT
WBS (points)
M ± SD	7.10 ± 3.85	7.10 ± 4.32	0.00 ± 3.99	0.80^d
Me (Q1 to Q3)	7.00 (5.00 to 9.00)	6.50 (4.50 to 10.00)	0.50 (−1.00 to 3.00)
Min to Max	0.00 to 15.00	0.00 to 15.00	−11.00 to 5.00
BWAT (points)
M ± SD	34.05 ± 9.70	35.40 ± 9.31	1.35 ± 5.79	0.28^c
Me (Q1 to Q3)	34.00 (28.00 to 42.00)	34.50 (28.00 to 43.00)	1.00 (−1.50 to 2.50)
Min to Max	17.00 to 49.00	17.00 to 54.00	−9.00 to 14.00
p-Value WBS^e	0.006^f	0.055^g	<0.001^b,g
p-Value BWAT^e	0.0004^f	0.09^g	<0.001^b,g

M0 versus M1.

M1 − M0.

Wilcoxon signed-rank test.

t-Test for paired samples.

Active ESWT versus placebo ESWT.

Mann–Whitney U test.

t-Test for unpaired samples.

DISCUSSION

Several biophysical agents have been well investigated to be useful in managing chronic wounds. Recent preliminary reports indicate a promising effect of ESWT, which might be introduced as an adjunctive method supporting the healing process.⁵⁹ According to the data from the systematic review, ESWT could also be a promising modality for acute wounds.⁶⁰ Nevertheless, there is still limited data, mainly including PUs and using a radial type of ESWT. To our knowledge, this is the first preliminary RCT study to demonstrate the positive clinical effects of radial ESWT supporting the healing of PUs.

This study revealed that beneficial changes might occur even following only a single radial ESWT session, supporting the immediate beneficial effect. Recent studies have not assessed short-term effects and measured outcomes in the longer perspective of using ESWT following 2–4 weeks and even 12 weeks. It should be noted that main location of PUs in both groups involved the sacral area (45% in the active-ESWT and 50% in the placebo-ESWT), and the remaining locations were in the minority. Wound location might have also affected the clinical response; however, in our opinion, the sacral area is particularly vulnerable to compression because most patients prefer to stay in the supine position.

A reduction in wound planimetric parameters due to the positive response to implementing ESWT was shown compared with the placebo-controlled ESWT intervention, where a significant increase in wound area was reported. As mentioned before, only one double-blind crossover RCT by Larking et al⁴⁶ conducted on a relatively small sample of nine ulcers (eight patients) observed a significant improvement in the ESWT group. They reported reduced wound area at the end of the ESWT phase for −0.09 and −0.33 cm² in both groups: placebo-ESWT first (n = 5) and active-ESWT first (n = 4), respectively.⁴⁶ In turn, we observed significantly greater improvement of −3.42 cm² after active-ESWT and regression with an increase in wound area of 1.09 cm² after placebo-ESWT.

There was also a favorable effect on the clinical wound condition in WBS and BWAT for inter- and intragroup comparisons after the active ESWT therapeutic session compared with sham ESWT, where a significant progression of wound worsening was observed. According to the WBS tool, we observed a significant improvement of 5.80 ± 3.09 points in the active-ESWT group and no changes of 0.00 ± 3.99 points in placebo-ESWT. In terms of BWAT score, we observed an improvement of −14.75 ± 6.54 points in the active-ESWT group and a worsening of 1.35 ± 5.79 points in placebo-ESWT.

The results of our study are similar to those published in the previous prospective clinical reports regarding wounds of different clinical etiology.^49

–52 Wolff et al,⁵² in their study assessed with WBS tool where a median positive difference was −14 points, which is very similar to our study. Also, they showed a significant correlation between the WBS and the wound surface. In turn, in their study, Porso et al⁴⁹ also used the BWAT score, which showed improvement from baseline to the 15-, 30-, and 90-day follow-ups, where a median value of 13 points was achieved.

Moreover, our study used together quantitative and qualitative methods to measure wound healing. Combining novel and precise planimetry with standard clinimetric assessment gives a more comprehensive overview of changes during wound healing. Also, other researchers used combined assessment tools; Porso et al⁴⁹ also assessed the size of the wound (cm²), and they used visual analog scale and BWAT score; Saggini et al⁵⁰ used wound dimensions (cm) and pain self-assessment numeric box scale; and Wolff et al⁵² used wound surface (cm²) and WBS score. Only Schaden et al⁵¹ used wound size as the main outcome measure.

To sum up, most of the authors indicated that further studies are needed before the clinical application of ESWT on chronic soft tissue ulcers can be proposed. Also, it was concluded that further clinical trials are needed to evaluate ESWT biophysical parameters and standardize the ESWT protocol for chronic ulcers. ESWT has the potential for effective wound healing, and its implementation in standard therapeutic procedures requires evaluation in well-conducted RTCs.

Therefore, it should be emphasized that our study is the first step to introducing ESWT as a potentially useful therapeutic device, and RCTs are currently ongoing. The researchers encourage more research to determine the ESWT mechanisms underlying the healing process. However, it should be remembered that conducting large multicenter studies in PUs might be organizationally and clinically complicated due to the wide variety of treatment procedures used in clinical centers and the problematic character of Pus, in which many factors affect treatment outcomes.

The fact of such limited reports on using ESWT in a selective group of patients with PUs within a single prospective project and RCT design is remarkable. This may be due to the difficulty of conducting an RCT protocol in such challenging wounds, which PUs undoubtedly are. The maintenance of the research regime, restrictive enrollment criteria, elimination of factors potentially affecting the study results, additionally the COVID-19 pandemic disturbing the possibility of conducting clinical trials with patients at risk (such as older people suffering from PUs) are just some of the difficulties. Based on our own experience, this reason may explain such limited scientific data on the discussed subject. Nevertheless, the use of ESWT for other chronic wounds is more widely documented; however, some of them present some minor or major methodological remarks that should also be pointed out.

Patient safety

Our clinical experience with the ESWT in chronic wounds demonstrates that these procedures are safe and have a negligible risk of adverse events. However, during the ESWT sessions, the occurrence of potential adverse events must be carefully observed and reported for patient safety. According to ESWT, these include typical complications such as painful sensations, bruising, petechiae, and soreness.

Our current observations enable us to describe some unusual adverse effects in the wound area, such as local bleeding episodes (vascular background) and uncontrolled hypergranulation tissue (inflammatory background). In this case, an effective method should be used to prevent bleeding (e.g., absorbable hemostatic sponge) and specialist antibacterial dressings (e.g., containing ionic forms of silver), which should be considered when the risk of infection occurs. It is strongly recommended to use sterile or single-use materials and instruments during ESWT procedures.

Study limitations

To our knowledge, the present study is the first preliminary and prospective double-blinded RCT that proved a positive effect of radial ESWT in promoting PUs healing. It was demonstrated that even a single application of radial ESWT demonstrates favorable clinical outcomes. Moreover, our study used quantitative and qualitative methods to measure wound healing. This study provides evidence that ESWT is a promising supportive modality that is noninvasive and safe. However, it is important to note that these findings should be interpreted with caution due to the preliminary character of this study. It should be pointed out that more ESWT applications consisting of a complete therapeutic session should be delivered to obtain more favorable and clinically relevant results. Also, a longer period of follow-up observations should be considered when the entire therapeutic session is performed, even up to the completed wound closure.

Moreover, it should be emphasized that clinical assessment should be supported and verified with objective measurement devices such as wound planimetry and other dedicated tools.

Practical implications

This study provides evidence for the clinical utility of radial ESWT applications in the management of PUs. This message could be favorable for scientists and clinical practitioners searching for safe and effective treatment strategies supporting wound healing. The key methodological aspects of the ESWT procedure, which should be kept in mind are as follows: to maintain aseptic conditions to minimize the risk of wound infection, the use of surgical drapes to protect the treatment area, the use of sterile ultrasound gel as a coupling agent between the ESWT transducer and the wound surface, the use of a sterile protective cover for the ESWT transducer, and the use of polyurethane film as a mechanical barrier between the wound surface and the ESWT transducer. In addition, the contact and labile technique is used during the treatment with the ESWT applicator head, and the treatment should begin from the wound edges, moving gradually to its center with a careful treatment of the entire surface, including the bottom of the wound. What is essential is not to neglect the treatment of the most profound areas of the wound and the so-called subcutaneous pockets.

INNOVATION

To our knowledge, the present study is the first preliminary double-blinded RCT that proved a positive and immediate clinical effect of radial ESWT in promoting chronic wound healing in the case of PUs. It was demonstrated that even a single application of radial ESWT demonstrates favorable clinical outcomes. Moreover, most of the previous clinical studies used the focused ESWT applicator. This study provides evidence that radial ESWT is also a promising supportive modality, which is noninvasive and safe, and it may be an adjunctive method for managing PUs.

KEY FINDINGS

This study provides preliminary evidence for the clinical utility and safety of radial ESWT in the management of PUs.

Even a single session of radial ESWT seems to be a promising and clinically effective supportive modality in the treatment of PUs.

There is still limited data regarding the usefulness of ESWT in PUs, especially in the radial applicator; therefore, further well-designed studies are needed.

Footnotes

AUTHORs' CONTRIBUTIONS

R.D.: Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, and Writing—review and editing; I.K.: Conceptualization, Data curation, Investigation, and Writing—review and editing; J.R.: Conceptualization, Funding acquisition, Methodology, and Writing—review and editing; K.W.: Conceptualization and Writing—review and editing; J.T.: Conceptualization, Formal analysis, Methodology, and Writing—review and editing; M.S.: Conceptualization, Formal analysis, Methodology, and Writing—review and editing.

ACKNOWLEDGMENTS AND FUNDING SOURCES

The authors would like to thank the patients sincerely for their participation in the study. We sincerely thank Dr. Yunghan Au from the Department of Medical Affairs of Swift Medical (Toronto, ON, Canada) for his invaluable support with accessing the planimetric smartphone application Swift Skin and Wound Mobile App. Also, we would like to extend our sincere thanks to the Operational Director of the ORPEA Poland (previously General Director of the senior center ‘Rezydencja na Dyrekcyjnej’ in Wroclaw) - Ms. Joanna Crowley, for her benevolence and organizational involvement in our research project. We declare that this research project was supported by the Ministry of Health subventions according to the number of STM.E020.20.100 from the IT Simple system of the Wroclaw Medical University, Poland. The project was supported by the Wroclaw Academic Hub in the MOZART program according to the number of BWU-26/2017/M6.

AUTHOR DISCLOSURE AND GHOSTWRITING

No competing financial interests exist. The content of this article was expressly written by the authors listed. No ghostwriters were used to write this article.

ABOUT THE AUTHORS

Robert Dymarek, PhD, is a physiotherapist, postdoctoral researcher, and assistant professor. His experience is in physical medicine, shock wave therapy, wound management, and objective assessment. Izabela Kuberka, MSc, PhDc, is a nurse, doctoral candidate, and research assistant. Her experience is advanced wound management and clinical wound assessment. Joanna Rosińczuk, PhD, is a nurse, senior researcher, and full professor. Her experience is geriatric medicine, wound management, and neurological nursing. Karolina Walewicz, PhD, is a physiotherapist, postdoctoral researcher, and assistant professor. Her experience is shock waves and clinical assessment. Jakub Taradaj, PhD, is a physiotherapist, senior researcher, and full professor. His experience is in physical medicine, wound management, lymphedema therapy, clinical assessment, and evidence-based medicine. Mirosław Sopel, PhD, is a biologist, senior researcher, and associate professor. His experience is basic science, cell biology, histology, immunochemistry, and biological mechanisms.

Abbreviations and Acronyms

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