Rotator cuff disease is the most prevalent cause of shoulder pain, responsible for 70% of all shoulder related clinician consultations [1,2]. Additionally, 20.7% of people diagnosed with rotator cuff tears (RCTs), will suffer from a full thickness tendon tear [3] and these tears can be debilitating as they cause pain and muscle weakness during shoulder elevation that restrict activities of daily living [4]. Current treatment options for full-thickness rotator cuff tears (RCT) consist of physiotherapy rehabilitation, corticosteroid injections, ortho-biologic treatments, and surgery. Surgery is often viewed as the best treatment choice, with numerous studies advocating for early surgical intervention in both traumatic and degenerative tears to avoid further tear development, muscle atrophy, and fatty infiltration. This notion is now being challenged by the fact that it has been shown that the rate of tear progression is often slow and may allow adequate time for conservative interventions [5]. However, the consensus on atraumatic indications for surgical treatment of rotator cuff tears is variable due to a lack of high-level studies and variability in available evidence to inform clinical decision making [6]. As a result, numerous studies have evaluated the outcomes of rotator cuff surgical repairs of traumatic and degenerative tears [7-12]. It has been found that clinical results are greater in acute traumatic tears with repairs performed within 6 months of injury [13]. However, a 2019 Cochrane review concluded that there is inconclusive evidence regarding whether rotator cuff repair surgery provides clinically meaningful benefits as measured by improvements in pain, function, and quality of life [14].

A systematic review by Heerspink et al, found no statistically or clinically significant difference in functional outcomes in patients when comparing surgical versus conservative treatments for RCT [15]. These findings were supported by a randomized controlled trial by Moosmayer et al, which failed to find a significant difference between surgery and conservative treatment 5 years post-intervention. The various limitations in the studies, including differing endpoints and inclusion criteria, make it difficult to draw firm conclusions [16], but they suggest that surgical intervention may not provide long term benefit over conservative management with this hypothesis in mind, several studies have substantiated the use of physical therapy in the management of atraumatic partial thickness rotator cuff tears [17-19]. However, there is inconclusive evidence to support the use of conservative treatments over surgical intervention for full thickness RCT [20]. As a result, conservative management and surgical interventions are often used in conjunction, with patients starting with conservative management. Transition from conservative treatment is then generally warranted and early operative treatment is likely if the patient does not respond well within the first 6-12 weeks and is younger than 60 years with healthy tendon and muscle environment [21].

Extracorporeal pulse activation therapy (EPAT), colloquially known as shockwave, is a novel, non-invasive treatment for musculoskeletal and peripheral nerve indications [22-23].

EPAT generates short pressure pulses from a handheld applicator which propagates low- amplitude acoustic waves into the tissue of the affected site. Initial clinical usage of shockwave was via extracorporeal shockwave lithotripsy as a minimally invasive treatment for fragmenting renal and ureteral stones [24]. EPAT began being used in the management of musculoskeletal disorders as further studies found that the shockwaves can generate interstitial and extracellular responses that cause a variety of beneficial effects that lead to tissue regeneration and significant alleviation of pain, thereby improving functional outcomes in injured tissue [25]. There are currently two forms of EPAT, radial and focused, available for clinical use. Radial shockwaves are generated by the acceleration of a projectile, typically via compressed air through a tube, at the end of which collides with an applicator that then makes contact with the target tissue, while focused shockwaves are generated within the applicator, focused by a lens, and then transmitted into the target tissue [26]. Only radial EPAT was utilized for treatment in this case, so it will be the focus of this report. The exact mechanism is not completely understood but the current proposed mechanism of action is centered around mechanotransduction that promotes neovascularization and early upregulation of angiogenesis-related growth factors, such as vascular endothelial growth factor (VEGF) receptor 2 [27]. Recent studies support this as they have demonstrated increased blood circulation and improvements in pain and function in some orthopedic indications [28-29]. Various randomized controlled trials on the use of EPAT for rotator cuff tendinopathy have been performed with varying outcomes, suggesting that additional high-level research is warranted [30-34]. To our knowledge, there is currently no published report on the use of (EPAT) colloquially referred to as Shockwave Therapy, in the treatment of full-thickness RCTs.

This report documents the case of a 61-year-old female with a history of left shoulder impingement, presenting with a full thickness tear of the supraspinatus tendon. The tear was confirmed clinically as she presented with positive empty can test, positive Neers impingement test, and 4/5 strength with external rotation. The tear was also confirmed radiographically with ultrasound and MR arthrogram imaging. At the time of her initial evaluation, the patient declined steroid injections due to the adverse risks associated with cortisone and had already tried and failed conservative management including physiotherapy and over the counter medications. The patient also had an active cancer diagnosis that ruled out orthoiologic intervention as they could potentially exacerbate her cancer. As she was also undergoing chemotherapy for the cancer, it made her a poor surgical candidate as well. The nature of the full thickness tear and the patient’s various comorbidities described left her with limited treatment options. EPAT was chosen as primary intervention to help alleviate the patient’s pain and allow her to regain functionality due to prior studies supporting its usage for rotator cuff pathology [35]. However, the patient experienced enormous clinically meaningful improvements in pain and function as characterized by a clinically significant improvement in Quick Dash score. Tendon healing as also radiographically confirmed via post-treatment MRI of the left shoulder without contrast

Treatment Plan: As shown in table 1, a minimum of 2000 pulses, with maximum of 3000 pulses were applied to the supraspinatus tendon and general shoulder region at each session using a radial EPAT device via V-actor applicator as per CuraMedix protocol. The patient underwent 2 initial series of 6 weekly treatments and a final series of 5 weekly treatments, with a gap of several months between each series, starting in July 2019 and completing in august 2020.

Table 1: Extracorporeal Pulse Activation treatment details including date of treatment, region treated, dosage (Bar), frequency, impressions, and applicator tip used. In all cases prior to 7/17 post-treatment with the V-actor was for 3000 impress/2.0 bar/31 Hz. After 7/17 the V-Actor was used as a pre-treatment per changes in CuraMedix protocol.

Treatment Plan:

Patient-Reported Outcome Measures

Patient reported significant limitations in function and pain and a retrospective pre- treatment Quick DASH score of 72.18. Following treatment, the patient recorded a Quick Dash score of 18.2, a difference of 53.98. This score change and the patient's corresponding symptom improvement can be considered clinically significant as it exceeds the minimum clinically important difference score (MCID) of 16-20 that has been established for the Quick Dash questionnaire [36].

Imaging

Ultrasound imaging at initial consultation showed full-thickness supraspinatus tear, which was then confirmed with follow-up MR Arthrogram. The pre-treatment MR arthrogram of the left shoulder in figure 1 illustrated a full thickness supraspinatus tear with small labral tears and tendinopathy of the bicep tendon. The corresponding radiologist’s report detailing the arthrogram's impressions is displayed in figure 2. The patient’s post-treatment MRI without contrast in figure 3 illustrated moderate rotator cuff tendinosis and a probable small tear of the supraspinatus tendon. The corresponding radiologist’s report detailing the MRI’s findings is displayed in figure 4. No full thickness supraspinatus tear was noted in the follow-up MRI.

Figure 1: MR Arthrogram with contrast of Left shoulder on 14-Jan-2019 illustrating a full thickness supraspinatus tear.

Figure 2: Radiologist report from pre-treatment MR Arthrogram with contrast of Left shoulder.

Figure 3: Post treatment MRI without contrast of the left shoulder on 19-Jun-2020 demonstrating improvement of prior full thickness tear supraspinatus tear into possible partial tear and tendinopathy.

Figure 4: Radiologist's report from Post-treatment MRI without contrast of the left shoulder.

This is a novel case report with several limitations that should warrant caution when interpreting its findings. The first limitation being that this is a single case report regarding one patient and EPAT is not traditionally used as a treatment modality for full thickness rotator cuff tears, so additional data is limited. However, the patient in this report experienced clinically significant improvements in pain and function that were supported by radiographic evidence of tendon healing. Therefore, the findings should be considered with caution, but the positive outcomes detailed in this report highlight that additional research into EPAT as a treatment modality for rotator cuff tears is warranted.

A second limitation of this report is regarding the difference in pre and post imaging modalities. Pre-treatment imaging consisted of an MR arthrogram with contrast, but the post- treatment imaging was an MRI without contrast. The cause of the difference in imaging modality was because the patient was asymptomatic at the time of her 6-month follow-up. As a result, the treating physician did not elect to repeat the arthrography for the follow-up MRI. The use of different imaging modalities can be considered a limitation as the difference could account for the changes and/or discrepancy in pre and post imaging. However, with regards to indications of full thickness RCT’s, MR arthrogram and MRI’s have been proven to possess sensitivity and specificity above 90% and are considered comparable to one another [38-40].

A third limitation of this report can be found in the timing of the treatment. The patient began receiving treatment 27 weeks after the MR arthrogram was performed. The length of time between diagnostic imaging and the start of the EPAT treatment, in addition to its concurrence with physiotherapy, weakens our ability to determine that EPAT played the primary role in the improvement of the full thickness tear. However, the patient reported no changes in symptoms prior to EPAT treatment despite physiotherapy but significant relief in symptoms after starting the EPAT treatment course. This strengthens our conclusion that the EPAT treatment was able to provide symptoms relief and interval healing of the RCT. A 4th and final limitation of this report was the retrospective collection of data using a QuickDash score rather than a full DASH score. However, studies show that a QuickDash score can be recommended instead of a full DASH score when assessing traumatic conditions [41].

In patients who are poor surgical candidates, Extracorporeal pulse activation therapy may be considered as a non-invasive supplemental therapy for full- or partial-thickness rotator cuff tears. The clinically significant improvements this patient experienced has caused us to more deeply consider and warrant additional research regarding EPAT’s potential as an intervention for rotator cuff tears. As previously discussed, despite full thickness rotator cuff tears presenting as a common shoulder pathology that people experience, they have limited viable treatment options beyond conservative management or surgical intervention. These limited treatment options have left millions of people subjected to an orthopedic treatment gap. If additional research can confirm and support the novel findings expressed in this report, EPAT could emerge as another viable intervention or adjunct for full thickness RCTs for all these patients that have been stuck in this treatment gap.

Dr. John Ferrell III was responsible for oversight of care for the patient, served as principal investigator for the report and authored the original manuscript. James Perry was responsible for administering the EPAT treatments to the patient and creating the original manuscript. Finally, Roosevelt Desronvilles was responsible for editing, formatting, and creating the final draft of this report. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Informed Consent Statement

Informed consent was obtained from all subjects involved in the case report.

Conflicts of Interest

The authors declare no conflicts of interest.

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