Extracorporeal Shock Wave Therapy in Shoulder Rehabilitation: Unlocking Motion and Reducing Post-Surgical Pain

By He-Bei He¹, Min-Cong Wang², Yong Hu², Cheng-Long Pan²

Affiliations

1. First School of Clinical Medicine, Guangzhou University of Chinese Medicine, Guangzhou, China
2. Department of Orthopaedic Surgery, The Fifth Affiliated Hospital of Southern Medical University, Guangzhou, China

doi: 10.29271/jcpsp.2025.06.749

ABSTRACT
Objective: To evaluate the effectiveness of extracorporeal shock wave therapy (ESWT) in improving pain, range of movement, and functional outcomes in patients with shoulder stiffness following rotator-cuff repair.
Study Design: Descriptive study.
Place and Duration of the Study: Department of Orthopaedic Surgery, The Fifth Affiliated Hospital, Southern Medical University, Guangzhou, China, from January 2021 to December 2023.
Methodology: Patients with postoperative shoulder stiffness after rotator-cuff repair who underwent ESWT (two sessions per week for four weeks) were enrolled. Outcomes assessed included shoulder range of movement, pain levels (numerical rating scale), Constant- Murley scores (C-M), and American Shoulder and Elbow Surgeon scores (ASES). Data were collected at baseline and at 1, 2, 4, and 6 weeks, and repeated-measures ANOVA was performed to assess changes over time.
Results: Sixty patients participated in the study. Significant improvements were observed across all parameters (p <0.001). Shoulder range of movement increased at all follow-up intervals (p <0.001). Pain scores decreased from a mean baseline of 7.81 ± 1.64 to 2.05 ± 1.61 at six weeks. Functional outcomes improved significantly, with C-M scores rising from 48.45 ± 9.78 to 78.50 ± 4.20 and ASES scores increasing from 46.08 ± 13.53 to 79.14 ± 4.29 by the end of the study. No adverse effects or complications related to ESWT were reported.
Conclusion: ESWT significantly enhances shoulder mobility, reduces pain, and improves function in postoperative rotator-cuff repair patients. It offers a safe and effective alternative for inclusion in rehabilitation protocols.

Key Words: Rotator-cuff repair, Extracorporeal shock wave therapy, Stiffness, Functional rehabilitation, Analgesia.

INTRODUCTION

The postoperative management of rotator-cuff repair encompasses a complex constellation of treatments aimed at restoring function, minimising pain, and enhancing the recovery process. Among the myriad complications that can arise postoperation, stiffness or frozen shoulder is one of the most prevalent, severely limiting the range of movement and impacting the quality of life.¹ The prevalence of postoperative stiffness following arthroscopic surgery is considerable and ranges from 3 to 23%.^1,2 This condition is particularly common after rotator-cuff repair, especially when early immobilisation and inadequate rehabilitation are involved.

The current treatment options for stiffness after rotator-cuff repair exhibit several disadvantages. Each modality has its limitations: While effective, arthroscopic capsular release invol-ves surgical risks and extended recovery time,^3,4 rehabilitation necessitates patient compliance and a prolonged treatment duration to achieve significant results,⁵ and intra-articular corticosteroid injections, though potentially beneficial, may pose risks of side effects and are not universally effective.⁶

 Extracorporeal shock wave therapy (ESWT), a non-invasive treatment modality, has garnered attention in the orthopaedic and rehabilitation fields for its potential to alleviate pain and promote tissue healing. Initially used for lithotripsy to break down kidney stones, ESWT has increasingly been applied to treat various musculoskeletal conditions, including tendinopathies, plantar fasciitis, and calcific shoulder tendinopathy. The therapy works by delivering shock waves to the affected area, which are believed to induce microtrauma that promotes the body's natural healing processes through neovascularisation, increased blood flow, and the release of growth factors.⁷

The rationale for employing ESWT as a therapeutic measure for shoulder stiffness post-surgery is based on its documented success in treating conditions with similar underlying pathology, such as inflammation, scar tissue formation, and reduced mobility. Preliminary studies have suggested that ESWT can be effective in improving the range of motion and reducing pain in patients with shoulder disorders.^8,9 However, the application of ESWT in postoperative shoulder stiffness remains underexplored, with limited studies directly addressing its efficacy in this specific condition.

Given the significant impact of postoperative shoulder stiffness on patient outcomes and the promising potential of ESWT as a treatment modality, this study aimed to rigorously assess the effectiveness of ESWT in treating this condition.

METHODOLOGY

This was a descriptive retrospective cohort study designed to assess the effectiveness of ESWT in the treatment of postoperative shoulder stiffness after rotator-cuff repair. The study population consisted of patients who underwent shoulder surgery at the Department of Orthopaedic Surgery, The Fifth Affiliated Hospital, Southern Medical University, Guangzhou, China, from January 2021 to December 2023 and developed postoperative stiffness. Eligibility criteria included patients aged 18 years or older, a diagnosis of shoulder stiffness within six months post- surgery, and a minimum of 6 weeks of follow-up after completing the treatment regimen. Shoulder stiffness was defined as a restriction of active and passive movements where elevation is less than 100° and external rotation is less than 50% of the contralateral shoulder's motion.¹⁰ Patients with calcific tendinopathy, rheumatoid arthritis, previous shoulder fractures, or neurological conditions affecting the shoulder were excluded. All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee, and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. Approval for this study was obtained from the Ethics Committee of the hospital.

Patient records were identified through the hospital’s electronic health record system associated with postoperative shoulder stiffness. The data extracted included demographic information (age and gender), medical history, details of the shoulder surgery performed (type and indication), onset of stiffness, duration before ESWT, rehabilitation progress, and any additional interventions employed.

Informed consent was obtained from all individual participants before receiving ESWT. Patients who had received ESWT were included in the ESWT cohort. The ESWT was performed using a focused shock wave device (RUIDI.SWT001, Shenzhen Ruide Medical Equipment Co., Ltd., China). The treatment protocol consisted of ESWT administered twice weekly for 4 weeks, with a frequency of 2.0 Hz and energy levels ranging from 2 to 4, depending on the patient's tolerance, and 1,500 shocks per session. The treatment head targeted the area around the involved shoulder joint. The details of each session, including the energy settings, number of shocks administered, and any side effects, were recorded.

The primary outcome of interest was the range of movement (ROM) of the affected shoulder (forward flexion, abduction, external rotation, and internal rotation), measured in degrees using a standard goniometre. Secondary outcomes included pain levels assessed using the numerical rating scale for pain (NRSP), Constant-Murley score (C-M), and the American Shoulder and Elbow Surgeon (ASES) shoulder score. These metrics were collected at the initial presentation of stiffness and at follow-up appointments after the completion of the ESWT protocol. The follow-up points were 1^st week, 2^nd week, 4^th week, and 6^th week, to describe the early outcome after ESWT.

Patient characteristics  and outcomes were summarised using descriptive statistics. The changes in ROM, pain, C-M scores, and ASES scores across time points were initially analysed using paired-samples t-tests. However, to address concerns regarding multiple comparisons and to evaluate the overall change in these variables across all time points simultaneously, a repeated-measures ANOVA was conducted. This approach is more appropriate for assessing within-subject changes over time and provides a single p-value for each outcome variable, reflecting the overall time effect. The normality of the differences was evaluated using the Shapiro-Wilk’s test to determine a normal distribution. A value of p <0.05 was considered statistically significant. All statistical analyses were performed using Python (version 3.12).

RESULTS

The review encompassed a cohort of 60 patients, consisting of 13 (21.7%) males and 47 (78.3%) females. The age of participants ranged from 53 to 80 years, with a mean age of 64.4 years. Patients were diagnosed with postoperative stiffness and received ESWT 4.4 ± 1.0 months after ARCR, ranging from 3 to 6 months. The right shoulder was more commonly involved in this study (n = 39, 65%). Prior to undergoing rotator-cuff repair, the number of patients experiencing supraspinatus tendon tears, subscapularis tendon tears, and both combined was 28 (46.7%), 11 (18.3%), and 21 (35%), respectively.

Data analysis using repeated-measures ANOVA indicated significant improvements in shoulder ROM across all time points compared to baseline (p <0.001 for all comparisons) (Figure 1). Specifically, forward flexion improved from a baseline of 74.42 ± 15.37 degrees to 87.01 ± 16.18 degrees in the first week, reaching 140.80 ± 26.56 degrees by the sixth week. Lateral flexion increased from 63.98 ± 11.80 degrees at baseline to 119.05 ± 20.72 degrees by the sixth week. Internal and external rotations showed similar progressions, with initial values of 32.30 ± 9.98 degrees and 19.28 ± 8.83 degrees improving to 65.37 ± 13.60 degrees and 48.69 ± 12.99 degrees, respectively at the sixth week. These increases were statistically significant over time (p <0.001, Table I).

Pain, evaluated using a numerical rating scale, demonstrated statistically significant reductions at each follow-up compared to baseline (p <0.001 across all time points, Figure 2A). Initial pain levels of 7.81 ± 1.64 decreased to 7.38 ± 1.85 in the first week, reaching 2.05 ± 1.61 by the sixth week (Table II).

Table I: Changes in range of movement.

Variables	Baseline	1st week	2nd week	4th week	6st week	p-value
Forward flexion	74.42 ± 15.37	87.01 ± 16.18	97.65 ± 18.17	118.48 ± 20.25	140.80 ± 26.56	p <0.001*
Lateral flexion	63.98 ± 11.80	76.08 ± 14.68	93.90 ± 20.81	106.75 ± 20.81	119.05 ± 20.72	p <0.001*
Internal rotation	32.30 ± 9.98	40.43 ± 11.60	45.59 ± 12.05	55.21 ± 12.78	65.37 ± 13.60	p <0.001*
External rotation	19.28 ± 8.83	22.38 ± 6.90	34.34 ± 11.94	41.11 ± 12.83	48.69 ± 12.99	p <0.001*
*Repeated-measure ANOVA for statistical analysis, illustrating the overall trend of progression over time.

Table II: Changes in pain and functional evaluation (repeated-measures ANOVA).

Variables	Baseline	1st week	2nd week	4th week	6st week	f-values	p-values
Pain	7.81 ± 1.64	7.38 ± 1.85	5.27 ± 1.89	4.56 ± 2.22	2.05 ± 1.61	153.02	p <0.001*
C-M score	48.45 ± 9.78	50.23 ± 10.40	62.72 ± 7.01	71.49 ± 5.33	78.50 ± 4.20	228.39	p <0.001*
ASES	46.08 ± 13.53	48.65 ± 9.13	61.77 ± 9.61	70.66 ± 6.75	79.14 ± 4.29	154.44	p <0.001*
C-M score: Constant-murley score; ASES: American shoulder and elbow surgeons. *Repeated-measure ANOVA for statistical analysis, illustrating the overall trend of progression over time.   Figure 1: Changes in shoulder range of movement (ROM) over time following extracorporeal shock-wave therapy. Significant improvements were observed in shoulder ROM across all time points compared to baseline. The increases in range of movement were also statistically significant over time.

Functional scores, including the C-M and the ASES scores, exhibited substantial improvements as well (Table II). Although improvements in the C-M and ASES scores were not statistically significant at the first week compared to baseline (p = 0.123 and p = 0.153, respectively), significant enhancements were observed by the second, fourth, and sixth weeks (Figure 2B, C). The C-M score increased from 48.45 ± 9.78 at baseline to 78.50 ± 4.20 by the sixth week. ASES scores improved from 46.08 ± 13.53 to 79.14 ± 4.29 by the end of the study period.

No patients reported any adverse effects or complications, such as localised pain/ discomfort, skin redness/erythema, swelling, and haematoma. The absence of side effects underscores the safety and tolerability of ESWT as a therapeutic modality in postoperative shoulder rehabilitation.

DISCUSSION

The unique contribution of this study is underscored by its findings that support the expanded use of ESWT as a standard care component in rehabilitating postoperative shoulder stiffness. The application of ESWT effectively reduces pain and enhances shoulder function, demonstrated by improvements in range of movement and notable pain relief, with no adverse side effects reported. Importantly, this study found that the ESWT treatment for postoperative stiffness following rotator-cuff repair provides a rapid onset of action and long-lasting effects. This research provides substantive data affirming ESWT's role as both an effective and a safe option, positioning it potentially as a cornerstone in evolving surgical recovery protocols.

In the specialised context of postoperative care following rotator-cuff repair, the application of ESWT offers unique advantages that distinguish it from other conventional treatment modalities for shoulder stiffness. Postoperative stiffness is a frequent complication arising due to a combination of postsurgical adhesions to the surrounding soft tissues and capsular contracture.¹¹

ESWT effectively targets these issues through its non-invasive mechanism, stimulating biological processes such as neovascularisation and growth-factor release to facilitate healing and enhance mobility.^7,12 This targeted approach directly addresses the physiological hurdles encountered after rotator-cuff repair, offering quicker symptomatic relief compared to traditional methods.

Figure 2: Longitudinal changes in clinical outcomes after extracorporeal shock-wave therapy. (A) (Pain score): Significant reduction from baseline at every follow-up point, with a consistent downward trend over time. (B) (ASES score): No significant change at 1 week; significant increases at 2, 4, and 6 weeks yielding an overall upward time-trend. (C) (Constant–Murley score): Similar to ASES, 1 week not significant; significant improvements at 2, 4, and 6 weeks with a significant time effect.
 

Physical therapy always requires long-term patient engagement and gradual improvements.¹³ Brislin et al.¹⁴ found that only 60% patients had resolution of stiffness by 5 months postoperatively. Despite rapid improvement of ROM, surgical interventions such as arthroscopic capsular release carry inherent risks and higher medical expenses.^3,15 The comparison with corticosteroid injections illustrates a significant difference; while injections may provide short-term relief,¹⁶ they lack the longer-term regenerative effects evident with ESWT and pose-potential side effects.¹⁷

This study further highlights the practicality of ESWT in reduc-ing stiffness and enhancing functional outcomes without the recovery latency typical of other interventions. By integrating ESWT into standard postoperative protocols, healthcare providers can offer a robust, evidence-based approach that not only addresses immediate symptoms but also supports sustained recovery and improved quality of life for patients undergoing rotator-cuff repair. In addition, the lack of significant side effects with ESWT enhances its appeal, making it a repeatable option for persistent or recurring stiffness without the complications linked to repetitive corticosteroid use.

The early findings of this study were significant improvements in ROM, and pain levels were observed by the first week of treatment with ESWT, aligned with the known immediate physiological impacts of shock-wave therapy.¹⁸ ESWT is recognised for its capacity to quickly induce anti-inflammatory effects and pain modulation through mechanisms such as the stimulation of nitric oxide production and the promotion of angiogenesis.¹⁹ These effects can contribute to the observed early changes in clinical symptoms such as pain reduction and increased mobility. However, the lack of significant improvement in functional scores, such as the C-M and ASES scores, within the first week might be attributed to several factors. Functionality scores often reflect a broader range of patient-centred outcomes beyond mere pain and mobility, including strength, endurance, and the ability to perform daily activities. These aspects generally require longer periods to manifest improvement, typically involving structural and muscular adaptations that take weeks or even months to develop.²⁰

Moreover, early functional assessment may not fully capture the patients’ subjective recovery experience due to the relatively short adaptation period following the initiation of therapy. As documented in previous research, the integration of functional gains often lags symptomatic relief because muscles and connective tissues need time to strengthen and reorganise following reduced stiffness and pain.²¹ This temporal disconnect is frequently noted in rehabilitation studies, where the functional scales catch-up with symptomatic improvements as the underlying musculoskeletal structures progressively regain full operational capacity.

Thus, while ESWT can rapidly address inflammation and pain, the more complex improvements in functionality—captured by comprehensive scoring systems—will typically lag as the patient's body adapts and adjusts to postoperative recovery demands. Continuous application of ESWT, alongside structured rehabilitation exercises, is likely necessary to translate these early symptomatic benefits into longer-term functional successes, as evidenced by improvements in C-M and ASES scores observed in subsequent weeks. The observed pattern underscores the importance of maintaining a consistent treatment protocol to fully leverage ESWT's benefits in postoperative rehabilitation.

While this study underscores the potential benefits of ESWT in alleviating postoperative shoulder stiffness following rotator cuff repair, several limitations must be acknowledged. The retrospective design poses inherent biases related to data collection and patient selection, possibly affecting the consistency and reliability of findings. Furthermore, the small sample size and single-centre setting may restrict the generalisability of these results; thus, larger multicentre studies are warranted to enhance external validity. The short follow-up duration, limited to six weeks, might not capture long-term sustainability and durability of the observed improvements, underscoring the need for extended follow-up periods to assess ongoing therapy requirements effectively. The absence of a control group restricts the ability to attribute improvements solely to ESWT, highlighting the need for randomised controlled trials comparing ESWT with standard treatments to delineate its relative effectiveness clearly. Additionally, early assessments indicated no significant changes in functional outcomes, despite symptomatic improvements, suggesting that functional gains may take longer to manifest. The reliance on subjective measures such as patient-reported pain and functional scores may introduce variability, and future research would benefit from incorporating objective measures such as imaging or biomarkers of inflammation to better understand the mechanisms and optimise the application of ESWT in postoperative rehabilitation for shoulder stiffness.

CONCLUSION

This study confirms the efficacy of ESWT in improving shoulder stiffness after rotator-cuff repair. ESWT effectively alleviates pain and significantly enhances shoulder mobility with no significant adverse effects. While improvements in functional scores are not pronounced at the early stage of treatment, patients' subjective functional experiences improve over time. This recovery pattern suggests that the combination of ESWT and structured rehabilitation exercises is critical for achieving long-term functional improvements. Future large-scale, multicentre randomised controlled trials are needed to further validate the long-term effects and mechanisms of ESWT in postoperative rehabilitation.

ETHICAL  APPROVAL:
The study has received approval from the Medical Ethics Committee of the Fifth Affiliated Hospital of Southern Medical University.

PATIENTS’ CONSENT:
Informed consent was obtained from all individual participants before receiving ESWT.

COMPETING  INTEREST:
The authors declared no conflict of interest.

AUTHORS' CONTRIBUTION:
HBH, YH, CLP: Conception and design of the study.
MCW, YH: Contributed to the acquisition of the data and revision of the manuscript.
YH: Analysis, interpretation of the data, and drafting of the manuscript.
HBH, CLP: Critical revision for important intellectual content.
CLP: Responsible for the overall content as guarantors.
All authors approved the final version of the manuscript to be published.

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