Durable Shoulder Pain Relief and Avoidance of Surgery Up To 5 Years Following 60-Day PNS Treatment

Abstract

Introduction

Shoulder pain can be a chronic, disabling condition resulting in major procedures like surgery that are invasive, costly, and pose significant risks to patients. Minimally invasive interventions that provide durable relief can improve outcomes while enabling patients to avoid accruing additional healthcare costs. The present survey study evaluated durability of pain relief in a real-world shoulder pain population following percutaneous 60-day peripheral nerve stimulation (PNS) treatment.

Methods

A cross-sectional follow-up survey assessed follow-up outcomes among patients who received 60-day PNS for chronic shoulder pain. Outcomes included patient-reported percent pain relief, average and worst pain scores, and patient impression of change in quality of life, physical function, and sleep. Patients also reported other treatments and interventions used for their shoulder pain since the 60-day PNS treatment including changes in medication usage.

Results

Among 489 survey participants (mean follow-up 21 months, range 6–60), 83% (405/489) reported no subsequent radiofrequency ablation, permanent implant, or surgery following 60-day PNS. Within this subset, 87% reported ongoing improvement in at least one domain at follow-up, including 71% who maintained ≥ 50% pain relief, and more than half who reported much or very much improved quality of life (61%), physical function (57%), or sleep (57%). Among those using PNS seeking to avoid surgery (n = 265), 81% reported no subsequent surgery, with 77% of those patients maintaining ≥ 50% pain relief. Outcomes were consistent across follow-up durations and shoulder pain etiologies.

Conclusions

This real-world evidence demonstrates that a large majority of responders to 60-day PNS may experience durable shoulder pain relief and other improvements, with benefits demonstrated up to 5 years post treatment. The low rate of progression to subsequent interventions including surgery suggests potential for healthcare economic benefit, supporting 60-day PNS as both a clinically effective and potentially economically advantageous approach for appropriate patients.

Key Summary Points

Why carry out this study?

Chronic shoulder pain affects millions of Americans and often leads to progressive treatments of increasing invasiveness and cost, including surgery and permanent implants, creating significant economic burden and potential for patient morbidity.

This study sought to assess the long-term durability of pain relief and rates of subsequent interventions following 60-day peripheral nerve stimulation (PNS) in patients with chronic shoulder pain.

What was learned from the study?

Among 489 survey participants with a mean follow-up of 21 months, 83% required no subsequent interventions (radiofrequency ablation (RFA), permanent implant, or surgery) following 60-day PNS, with 87% of these patients maintaining clinically meaningful improvements in pain, quality of life, function, and/or sleep.

The high rate of surgery avoidance (81% among those seeking to avoid surgery) and low progression to permanent implants (5% overall) suggests 60-day PNS may disrupt the typical treatment progression, potentially yielding healthcare cost savings.

The durability of outcomes across different follow-up durations (up to 5 years) and shoulder pain etiologies supports 60-day PNS as both a clinically effective and potentially economically advantageous approach for appropriate patients.

Introduction

Shoulder pain stands as one of the most prevalent musculoskeletal issues, with up to 67% of individuals experiencing shoulder complaints during their lifetime [1]. The etiology of shoulder pain is diverse, encompassing a range of conditions including degenerative shoulder disease and osteoarthritis (OA), persistent postoperative pain, musculoskeletal injuries such as rotator cuff tears, adhesive capsulitis, neuralgia, and hemiplegic shoulder pain. These widely divergent causes contribute to the complexity of diagnosis and treatment in clinical practice. More than half of new shoulder pain episodes persist beyond 6–18 months, indicating a substantial risk of transitioning to chronic pain with significant associated economic costs due to healthcare utilization and pain-related disability [2–4].

Conservative management options for shoulder pain include pain medications, physical therapy, and joint injections. Patients with refractory pain may proceed to neuroablative procedures or more costly or invasive interventions such as permanent neurostimulator implants or shoulder surgeries. Common shoulder surgeries such as rotator cuff repair (RCR) and shoulder arthroplasty can incur thousands of dollars of costs and are associated with high rates of postoperative opioid use. Opioid use following surgery has the potential for related complications such as dependence and misuse—even among opioid-naïve patients undergoing elective shoulder surgery, 8–14% will continue with prolonged opioid medication use after surgery [5, 6]. Arthroscopic and open shoulder surgeries also carry risk of ineffectiveness (in the only sham-controlled trial evaluating shoulder surgery, there were no differences in outcomes between sham surgery and labral or biceps tendon repair [7]). Complications can range from shoulder stiffness and instability to infection and persistent postoperative pain [8, 9].

The number of primary shoulder arthroplasties increased by over 100% from 2011 to 2017, while rotator cuff repair rates increased by 1.6% per year from 2007 to 2016 and at an even higher rate among Americans over 50 years old [10, 11]. Confronting this rising incidence of surgeries requires novel solutions that can serve as definitive treatment options. Ideally these treatments should be implementable before major cost-incurring interventions, but would also be effective in the 20% of patients who develop persistent pain after surgery [3, 12, 13].

Peripheral nerve stimulation (PNS) is increasingly recognized as a tool for the treatment of pain in many regions of the body including the shoulder. One approach involves a US Food and Drug Administration (FDA)-cleared and commercially available percutaneous 60-day PNS treatment that has been found in prospective studies in the shoulder, back, and extremities to produce significant rates of long-term pain relief with commensurate improvements in function and quality of life, reductions in disability, and/or reductions in analgesic consumption [14]. This 60-day PNS approach was first studied in the shoulder for hemiplegic pain and shoulder impingement syndrome, and studies have since highlighted its applicability for a variety of other shoulder pain etiologies including osteoarthritis, post-traumatic pain, and postoperative pain [15–19]. A previous cross-sectional survey study found a majority of patients who experienced significant improvement in pain at the end of the 60-day PNS treatment continued to report such improvement through 24 months or longer [20].

Based on the durability of pain relief following percutaneous 60-day PNS in prospective studies and real-world evidence, the objective of the present cross-sectional survey study was to provide insights into the long-term outcomes of patients treated for shoulder pain with 60-day PNS in routine clinical practice across a wide range of etiologies and populations. In addition to assessing pain relief and other patient-reported outcomes through up to 5 years of follow-up, the study also evaluated progression to other interventions including radiofrequency ablation (RFA), permanent neurostimulator implant, and shoulder surgery to determine the potential cost avoidance associated with successful 60-day PNS treatment.

Methods

Study Design and Population

This study was a cross-sectional follow-up survey study of patients who previously received treatment of shoulder pain with percutaneous 60-day PNS (SPRINT^® PNS System, SPR Therapeutics, Cleveland, OH). Patients were included who received the 60-day PNS treatment targeting shoulder pain between April 2018 and January 2024, were ≥ 18 years of age, had not opted out of communications from the device manufacturer, and had an email address and/or mobile phone available. The present analysis focuses on survey participants with ≥ 50% pain relief at the end of their 60-day PNS treatment (EOT) to assess long-term outcomes in a population of EOT responders.

Ethical Approval

The study was approved by the WIRB-Copernicus Group Institutional Review Board (WCG-IRB, #2042073) with a waiver of documentation of informed consent. The survey included a consent agreement that acknowledged the use of de-identified survey data for research purposes. The study was performed in accordance with relevant portions of the Declaration of Helsinki.

Cross-Sectional Survey Procedures

The survey utilized a web-first, sequential, mixed-mode design. Eligible patients with an active mobile number available received a prenotification text message of the pending survey approximately 7 days prior to survey distribution. The survey was then distributed via text message and email with an initial invitation followed by a reminder within 3–4 days. Non-respondents received one phone call attempt with a voicemail left (if possible) by a study representative as a reminder with the option to complete the survey by phone, followed by a final text and email reminder within 7 days of the phone call attempt.

The first page of the survey included a consent agreement that acknowledged the use of de-identified survey data for research purposes. If a survey recipient declined the consent agreement, the survey was ended, and patients were excluded from further survey distribution attempts and data analysis. Patients could also opt out at any time from the text and email survey invitations. Patients were compensated with a US $100 electronic gift card for their time to complete the follow-up survey. Survey data were collected from June 2024 to August 2024.

Percutaneous 60-Day PNS Treatment

All survey recipients previously underwent a percutaneous 60-day PNS treatment targeting their shoulder pain. This treatment involves the placement of fine wire coiled leads, typically under ultrasound or fluoroscopic guidance, to stimulate one or more nerve targets innervating the region of pain in the shoulder (e.g., suprascapular nerve, axillary nerve, brachial plexus). The leads are designed to be placed remote (e.g., approx. 1 cm) from the target nerve(s) to deliver electrical stimulation from an external pulse generator mounted on the skin surface. Stimulation parameters typically range from 5 to 150 Hz with asymmetric charge-balanced biphasic pulses, from 0.2 to 30 mA amplitudes, and pulse durations of between and 10 and 200 µs. The two most common stimulation modalities for shoulder pain are lower frequency (e.g., 12 Hz) settings targeting efferent nerve fibers such as the terminal branches of the axillary nerve to elicit comfortable, cycling motor activity, or higher frequency (e.g., 100 Hz) stimulation targeting afferent nerve fibers to produce comfortable sensations in the region of pain. At the conclusion of the 60-day treatment period, the leads are removed with gentle traction and patients proceed to follow-up as directed by their physician.

Outcomes and Analysis

The present analysis focuses on survey participants who were 6–60 months from the start of the 60-day treatment. The survey included patient reported outcomes based on validated pain and other related measures. Patients reported their average pain (Brief Pain Inventory Short Form item #5, BPI-5) and worst pain (BPI-3) on an 11-point numerical rating scale (NRS) in the previous week as well as their overall percent pain relief from 0 to 100% (BPI-8) at the time of survey completion. Changes in quality of life, physical function, and sleep were each assessed on a 7-point patient impression of change scale from very much worse (− 3) to very much improved (+ 3) where 0 corresponds to no change. Additional questions collected demographic information, causes of shoulder pain, and other interventions used since completing the 60-day PNS treatment. Patients were asked to report qualitatively whether their analgesic medication usage was increased, decreased, stopped, or unchanged since before the 60-day PNS treatment. Follow-up survey data for each participant were combined with existing database records including baseline and treatment characteristics and outcomes at EOT.

To assess the long-term effects of 60-day PNS, patients were categorized into three groups: (i) long-term responders who received definitive treatment from the 60-day PNS system, defined as sustained response in at least one of four domains: pain relief (≥ 50%), or clinically meaningful improvement in quality of life, physical function, or sleep (at least minimally improved, or impression of change ≥ 1) at the time of survey completion with no escalation of therapy indicated by advancing to subsequent interventions on the treatment algorithm (i.e., no report of subsequent RFA, permanent neurostimulator implant, or surgery); (ii) long-term non-responders who did not maintain clinically meaningful improvement in at least one domain but also reported no escalation of therapy; and (iii) patients who reported escalation of therapy by proceeding to another subsequent intervention after 60-day PNS. Physical therapies and integrative treatments could be used in complement to interventions like 60-day PNS and in the present analysis were not considered to be an escalation of therapy or advancement along the treatment continuum.

As a follow-up survey administered between 6 and 60 months after completion of the percutaneous 60-day PNS treatment, safety was not specifically evaluated in this study. The safety profile of the 60-day PNS treatment has been documented in previous studies and reviews [14, 21–23]. All data are summarized descriptively as mean (standard deviation, SD) or as proportions of survey participants.

Results

Survey Population and Treatment Characteristics

The cross-sectional survey was conducted from June to August 2024, with 1217 patients meeting the inclusion criteria. A total of 489 completed surveys were returned (40% overall completion rate). Survey completion rate was highest among patients in the first 2 years following 60-day PNS treatment (50%), though significant numbers of responses were also received in subgroups with longer follow-up durations. Those with multiple modes of survey distribution (i.e., both email and mobile number available) also completed surveys at higher rates (48% overall and 61% among those in the first 2 years of follow-up).

The survey participant population averaged 66 (SD 14) years of age and was majority female, white, and non-Hispanic (Table 1). Average shoulder pain prior to starting 60-day PNS was moderate to severe with a mean score of 6.0 (SD 1.9) out of 10 (Table 2). The most frequently reported cause of chronic shoulder pain was injury or trauma, followed by osteoarthritis, prior surgery, and stroke, with 141 participants (29%) reporting multiple causes of pain (Table 2). Example conditions reported in the “Other” category included complex regional pain syndrome, nerve pain, cancer, cervical spine conditions, and non-specific shoulder pain. Among the participants reporting persistent postoperative pain, types of surgery included rotator cuff repair (n = 46, 9%), total or partial shoulder arthroplasty (n = 34, 7%), and others such as labrum repair, biceps tenodesis, cancer-related and spine-related surgery (n = 44, 9%).

Table 1.

Participant demographics

Total sample size	n = 489
Age, years, mean (SD)	66 (14)
Sex
Female, % (n)	65% (318)
Male, % (n)	35% (169)
Prefer not to answer, % (n)	< 1% (2)
Race
American Indian/Alaskan Native, % (n)	2% (10)
Asian, % (n)	2% (11)
Black/African American, % (n)	11% (52)
Native Hawaiian/Pacific Islander, % (n)	< 1% (3)
White, % (n)	79% (386)
Prefer not to answer, % (n)	8% (39)
Ethnicity
Hispanic or Latino, % (n)	6% (31)
Not Hispanic or Latino, % (n)	84% (412)
Prefer not to answer, % (n)	9% (46)

“Prefer not to answer” includes those who specified that response as well as participants who left the optional field blank

SD standard deviation

Table 2.

Shoulder pain history

Baseline average pain, mean (SD)	6.0 (1.9)
Baseline worst pain, mean (SD)	8.7 (1.5)
Cause of shoulder paina
Injury/trauma, % (n)	49% (242)
Osteoarthritis (OA), % (n)	43% (208)
Persistent postsurgical, % (n)	22% (109)
Stroke, % (n)	3% (13)
Other/unsure, % (n)	19% (91)
Previous surgeriesa
Rotator cuff repair, % (n)	9% (46)
TSA/PSA, % (n)	7% (34)
Other/unsure, % (n)	9% (44)
Used 60-day PNS in attempt to avoid surgery
Yes, % (n)	54% (265)
No, % (n)	24% (115)
Already had surgery, % (n)	22% (109)

All proportions are from total sample size (n = 489)

SD standard deviation, OA osteoarthritis, PNS peripheral nerve stimulation, TSA total shoulder arthroplasty, PSA partial shoulder arthroplasty

^aPatients had the ability to select multiple causes of pain and multiple previous surgeries as applicable

Survey participants had a mean follow-up duration of 21 (SD 13) months from the start of their 60-day PNS treatment (start of treatment, SOT) at the time of survey completion. For analysis purposes, the population was divided into cohorts ranging from 6–11 months post SOT to 48–60 months (Table 3). More than three-quarters (79%) received at least one lead targeting the suprascapular nerve. Additional nerve targets included the terminal branches of the axillary nerve at the deltoid, axillary nerve at the quadrangular space, and brachial plexus (Table 3).

Table 3.

60-day PNS treatment characteristics

Time since start of 60-day PNS treatment
6–11 months, n	154
12–17 months, n	88
18–23 months, n	82
24–35 months, n	90
36–47 months, n	51
48–60 months, n	24
Number of leads
Single, % (n)	58% (285)
Dual, % (n)	42% (204)
Nerve targetsa
Suprascapular nerve, % (n)	79% (385)
Axillary nerve (deltoid), % (n)	40% (198)
Axillary nerve (quadrangular space), % (n)	15% (75)
Brachial plexus, % (n)	3% (14)
Other, % (n)	6% (29)

PNS peripheral nerve stimulation

^aMay include multiple nerve targets per patient (e.g., for dual lead systems)

Long-Term Outcomes and Other Interventions

Overall, 83% (405/489) of patients reported no subsequent RFA, permanent implant, or surgery following 60-day PNS. The remaining 17% (84/489) reported one or more of those interventions suggesting escalation of therapy or advancement along the treatment continuum (e.g., due to a return of symptoms). RFA was reported by 2% (n = 12), permanent neurostimulator implant by 5% (n = 25), and subsequent shoulder surgery by 10% of patients (n = 51). Overall, these interventions were reported at slightly increasing rates with longer durations of follow-up (Fig. 1). For patients who reported dates of subsequent interventions, RFA, permanent implant, and surgery occurred an average of 17 (SD 14) months, 9 (SD 5) months, and 12 (SD 11) months post start of PNS, respectively.

Fig. 1.

Above: bars represent the proportion of survey participants reporting no subsequent intervention (radiofrequency ablation (RFA), permanent neurostimulator implant, or surgery) following 60-day peripheral nerve stimulation (PNS), stratified by months from start of treatment. Below: circles beneath x-axis represent proportions of patients avoiding subsequent intervention who also reported durable improvement following 60-day PNS in at least one domain including percent pain relief (≥ 50%) or clinically significant improvement in quality of life, physical function, or sleep (at least minimally improved, or ≥ 1 on a PGIC scale from  − 3 to + 3 where 0 = no change)

Of the patients reporting no subsequent intervention, 87% (353/405) were defined as long-term responders with sustained improvement in at least one domain including pain (≥ 50% relief) and/or clinically significant improvement (at least minimally improved) in quality of life, physical function, or sleep, with a mean pain relief of 68% (SD 28%) among responders. Among these long-term responders, 66% (234/353) were multidomain responders with clinically significant improvement in all four domains, and 87% (307/353) had improvement in at least three of four domains. Proportions of long-term responders were consistent across follow-up durations (Fig. 1). Average and worst NRS pain scores reflected similar patterns, wherein long-term responders also tended to report sustained reductions in average and worst pain score from the end of treatment to the time of follow-up (Table 4).

Table 4.

Patient-reported percent pain relief, average pain, and worst pain at baseline, end of the 60-day PNS treatment, and follow-up

	Baseline	EOT	Follow-up
Patient-reported percent pain relief, mean (SD)
All survey participants (n = 489)	n/a	76% (18%)	57% (34%)
Long-term responders (n = 353)	n/a	78% (17.0%)	68% (28%)
Long-term non-responders (n = 52)	n/a	67% (19%)	5% (10%)
Subsequent intervention (n = 84)	n/a	71% (17%)	43% (35%)
Average pain, mean (SD)
All survey participants (n = 489)	6.0 (1.9)	2.3 (2.0)	3.6 (2.6)
Long-term responders (n = 353)	5.9 (1.9)	2.3 (2.0)	3.0 (2.4)
Long-term non-responders (n = 52)	5.9 (1.9)	2.1 (1.9)	6.2 (2.1)
Subsequent intervention (n = 84)	6.4 (2.0)	2.7 (2.0)	4.3 (2.6)
Worst pain, mean (SD)
All survey participants (n = 489)	8.7 (1.5)	4.0 (2.6)	4.4 (3.0)
Long-term responders (n = 353)	8.7 (1.5)	3.8 (2.6)	3.8 (2.8)
Long-term non-responders (n = 52)	8.6 (1.3)	4.3 (2.4)	7.6 (1.6)
Subsequent intervention (n = 84)	8.8 (1.5)	4.5 (2.7)	5.2 (2.9)

SD standard deviation, EOT end of treatment, PNS peripheral nerve stimulation, n/a not applicable

Regarding pain relief alone, 71% (287/405) reported ≥ 50% sustained pain relief (Fig. 2). More than half of those patients (173/287) further met a higher threshold of ≥ 80% pain relief, while some additional patients reported 30–49% pain relief bringing the total to 80% (322/405) of patients with ongoing clinically meaningful relief (≥ 30%).

Fig. 2.

The proportions of patients avoiding subsequent intervention are shown who reported ≥ 80%, ≥ 50%, and ≥ 30% pain relief at the time of follow-up. PNS peripheral nerve stimulation

In addition to durable pain relief, large majorities of those with no subsequent intervention reported clinically significant improvements (i.e., at least minimally improved) in quality of life (80%, 323/405) or physical function (79%, 321/405), with 61% (248/405) and 57% (231/405) further reporting much or very much improved quality of life or physical function, respectively (Fig. 3). Only patients who reported difficulty with sleep at baseline were included in the impression of change in sleep, and 79% (291/370) reported clinically significant improvement with 57% (211/370) much or very much improved. These impressions of change in quality of life, physical function, and sleep were also consistent across follow-up durations. More than 66% of this cohort who had medication usage at baseline (245/369) reported reduction or cessation of pain medications, with only 9% reporting any increases compared to their pre-PNS baseline (Fig. 4).

Fig. 3.

Patients avoiding subsequent intervention are summarized categorically based on impression of change in a quality of life, b physical function, and c sleep at the time of follow-up (for those patients who reported difficulty sleeping at baseline), stratified by months from the start of the 60-day peripheral nerve stimulation (PNS) treatment

Fig. 4.

Proportion of patients avoiding subsequent intervention who reported changes in pain medication usage at the time of follow-up relative to before starting the 60-day peripheral nerve stimulation (PNS) treatment, stratified by months from the start of treatment

Among the most common causes of shoulder pain (e.g., injury, osteoarthritis (OA), postoperative, stroke), roughly similar proportions of patients, ranging from 81% to 88%, reported no subsequent intervention following 60-day PNS. Among those patients, the rates of sustained clinically significant improvement in at least one domain ranged from 86% among patients with OA-related pain to 91% among patients with post-injury pain or stroke. Rates of sustained pain relief alone were also consistent across shoulder pain etiologies (Fig. 5).

Fig. 5.

Proportion of patients avoiding subsequent intervention who reported ≥ 80%, ≥ 50%, and ≥ 30% pain relief at the time of follow-up, by reported causes of shoulder pain. Patients could report more than one cause of pain and may appear in multiple subgroups. OA osteoarthritis

Surgery Avoidance

A subset of survey participants (n = 265) reported using the 60-day PNS treatment in the hopes of avoiding shoulder surgery. Overall, 81% of these patients (215/265) reported no subsequent shoulder surgery at the time of follow-up, including 84% (143/171) who were within 24 months of the 60-day PNS treatment and 77% (72/94) who were 24–60 months from the start of treatment. Among those avoiding surgery after 60-day PNS, 91% (196/215) were long-term responders with clinically significant improvement in at least one domain and mean percent pain relief among those responders averaging 70% (SD 28%) at the time of follow-up.

Patients avoiding surgery also more consistently avoided pursuing other subsequent therapies and treatments. For example, 98% (211/215) reported no RFA after the 60-day PNS treatment, 97% (208/215) reported no permanent neurostimulator implant, and 95% (205/215) reported no new medications. Additionally, among those who used pain medications prior to 60-day PNS, 71% (139/197) reported reducing or stopping medication use compared to pre-PNS baseline.

Patient Satisfaction

Across all survey participants, patients reported a mean satisfaction score with their 60-day PNS treatment of 4.2 (SD 1.1) on a scale from 1 (very dissatisfied) to 5 (very satisfied). Mean satisfaction was similar across follow-up durations, ranging from 4.0 to 4.4. Mean satisfaction was highest among long-term responders (4.5 [SD 0.7]) relative to long-term non-responders (2.4 [SD 1.1]) and the patients who advanced to subsequent intervention after 60-day PNS (3.9 [SD 1.2]). Satisfaction with the 60-day PNS treatment was also particularly high among the 215 patients who sought to and did successfully avoid surgery (4.4 [SD 0.9]).

Discussion

This long-term cross-sectional follow-up study of 489 patients who received 60-day PNS for chronic shoulder pain demonstrates sustained benefits across multiple clinically relevant measures. Most patients (83%) did not require subsequent interventions such as RFA, permanent implant, or surgery during the follow-up period, which averaged 21 months and extended up to 5 years post treatment. Among these patients, 87% maintained clinically meaningful improvement in at least one domain including pain relief, quality of life, physical function, and/or sleep, with a majority improving in all four domains. Long-term improvements were particularly robust in the surgery avoidance cohort where 81% of patients successfully avoided surgery. The durability of response was notably consistent across different shoulder pain etiologies and follow-up durations. These findings were further supported by reported reductions in pain medication use and high patient satisfaction scores, suggesting that 60-day PNS may provide a durable solution for many patients with chronic shoulder pain while reducing the need for more invasive interventions.

Patients with shoulder pain typically progress through a stepwise treatment algorithm, beginning with conservative therapies like analgesic medications and injections before advancing to more invasive interventions. In this context, the low rate of treatment escalation following 60-day PNS (17% overall moving on to RFA, permanent neurostimulator implant, or surgery) represents a clinically meaningful improvement over the typical therapy progression. While some patients did advance to permanent implants (5%) or surgery (10%), these interventions occurred an average of 9 and 12 months post treatment, respectively, suggesting that 60-day PNS provided an extended period of relief even in those who did require further intervention. The low utilization of radiofrequency ablation (2%) aligns with its still-developing role in shoulder pain management compared to other areas where RFA is more prevalent like low back pain [24]. The 60-day PNS treatment has a strong, established safety profile [14, 25], and its ability to prevent or substantially delay progression to potentially more invasive, higher-risk, and costlier procedures in 83% of surveyed patients represents a significant shift in the traditional treatment trajectory, potentially reducing both patient morbidity and healthcare resource utilization.

The high rate of surgery avoidance (81%) among those who received 60-day PNS with that goal represents substantial benefit to patients, reduction in risk, and potential healthcare cost savings. While the proportions of symptomatic patients requiring surgery is difficult to estimate, the cost and incidence of surgical intervention have risen rapidly including both RCR following rotator cuff injury and TSA [26–28]. For example, reimbursement costs for total shoulder arthroplasty can exceed $18,000 depending on the setting [29, 30]. These estimates are rising and also often underrepresent the full economic burden, as they may not include costs of postsurgical rehabilitation, management of complications and readmission, or lost productivity during recovery. The ability of 60-day PNS to help patients manage pain while avoiding surgery is particularly noteworthy given that 91% maintained clinically meaningful improvement in at least one outcome and 77% of these patients reported sustained pain relief (≥ 50%) at follow-up. These data suggest that 60-day PNS provided a durable alternative rather than merely delaying inevitable surgical intervention. This is further supported by the low rates of other subsequent interventions in this group, with 95–98% avoiding new medications, RFA, and permanent neurostimulator implants. Given that the survey population attempting to avoid surgery was roughly evenly split between osteoarthritis and injury/trauma patients, these findings suggest percutaneous 60-day PNS may provide substantial cost savings across multiple shoulder pain etiologies through durable improvements in pain, function, and quality of life, as well as reduced surgical utilization.

Sixty-day PNS treatment has been recognized not only for its potential to provide patients with durable pain relief but also to support informed treatment planning. While permanent PNS options are warranted in some patients whose pain is best managed long-term by ongoing stimulation, a 60-day treatment may help illuminate the potential efficacy of stimulation with an initial treatment period that greatly exceeds typical conventional trials. Conventional brief trials can be challenging to interpret and may provide false-negative or false-positive results in some patients, potentially leading to suboptimal patient selection for permanent implants [31]. The 60-day PNS treatment duration allows for a more comprehensive assessment of patient response to neurostimulation, including the stability of pain relief during stimulation and the patient’s ability to effectively manage the therapy.

In addition to clinical benefit and therapeutic planning, recent economic analyses have suggested that initiating PNS with a 60-day treatment may be more cost-effective than starting with a brief conventional trial. In a large Medicare claims analysis, Dickerson et al. found that 41% of patients who received brief PNS trials advanced to permanent systems, compared to only 18% of patients who started with 60-day PNS treatment [32]. Rates of permanent system explantation were also found by Dickerson et al. to be lower in the those starting with 60-day PNS (4% of permanent implants) compared to those starting with a brief trial (7% of permanent implants) [32]. This has substantial economic implications given that Dickerson et al. reported lower average reimbursement costs for the 60-day PNS pathway compared to the conventional trial-to-permanent pathway, and the total cost per successful outcome was also significantly less (approximately 2.5 times lower). While the study by Dickerson and colleagues was agnostic to pain indication, the present shoulder pain cohort demonstrated only a 5% rate of permanent implant progression, suggesting particularly effective cost avoidance in this indication. The durability of outcomes observed in the present study provides real-world validation of the economic advantage of 60-day PNS, as the majority of patients achieved sustained pain control without incurring the additional costs associated with implantation, explantation, and/or ongoing maintenance of a permanent implant.

The durability of pain relief in this study complements and reinforces findings of durable, long-term pain relief from previous clinical trials of 60-day PNS for shoulder pain and other indications in the back and extremities [14]. The high proportion of patients maintaining ≥ 50% pain relief without subsequent intervention at an average follow-up of 21 months is also noteworthy as an extension of other real-world studies that have focused primarily on outcomes through the end of the 60-day treatment period [16, 17, 33]. The present study not only demonstrates long-term durability but also shows consistency across multiple outcome measures, with improvements in pain corresponding to sustained enhancements in quality of life, physical function, and/or sleep (Fig. 3). This durability may be attributed to the proposed mechanism of the 60-day PNS system, which provides for both active pain relief through direct nerve stimulation and potential reconditioning of pain processing through neuroplastic changes to reduce central sensitization [34]. The consistency of outcomes across follow-up durations from 6 months up to 5 years further supports the stability of these therapeutic effects.

Study Limitations

A limitation of the present study is that follow-up data were collected as part of a cross-sectional survey and did not include a prospective, longitudinal cohort design to assess patients at multiple follow-up timepoints post treatment. While cross-sectional outcomes may not capture natural changes in the underlying pain state over time, patients pursuing interventions like PNS typically exhibit refractory chronic pain symptoms. In non-permanently implanted patient populations that can be challenging to follow in the real-world setting, cross-sectional surveys also highlight a potential approach to broaden the availability of real-world data for long-term follow-up. This is particularly valuable when provider interactions and electronic medical records may not be available for various reasons [16] and when prospective clinical trials are costly and lengthy to conduct. Although there was an uneven distribution of patients across follow-up durations with fewer patients beyond 3–4 years, the inclusion of data up to 5 years post treatment represents a meaningful extension of the currently available evidence base for long-term 60-day PNS outcomes.

The survey methodology introduces additional considerations. The response rate (40% overall and 50–61% among select cohorts) is considered strong in the present environment for web-based surveys [35–38]. While there is a potential for nonresponse bias in survey-based studies, recent survey methodology research has suggested there may be little relationship between survey response rates and nonresponse bias [39]. Hendra and Hill also found that pursuit of higher response rates can result in trade-offs such as increased survey fielding times that create additional measurement problems [39]. A successive wave analysis was also conducted in the present study to further assess the potential for nonresponse bias and found no significant relationship between outcomes and the cumulative number of reminders needed for survey completion. This methodological approach compares outcomes from early participants to those from late participants (who responded only after additional contact attempts), based on the established principle that late participants more closely resemble non-participants than do early participants [40]. While not eliminating the possibility of nonresponse bias, this evidence strengthens confidence that the results are representative of the broader treated population.

While the survey was distributed by the device manufacturer, efforts to reduce self-report bias included the use of validated patient-reported outcome measures (PROMs). The use of validated PROMs and a web-based survey platform reduces variability in delivery of outcome measures and increases data reliability. Changes in analgesic medication usage were based on patient report of change rather than more objective measures like medication diaries; accordingly, changes in medication usage were not incorporated in the definitions of treatment response and those data are presented descriptively as a secondary survey outcome. Overall, the consistency of these survey outcomes with published prospective data supports the validity of the findings in the real-world setting. Additionally, while not a formal economic model, the study findings reveal meaningful patterns in healthcare utilization that point to opportunities for cost avoidance in clinical practice.

Conclusions

This real-world evidence of sustained improvements in pain and other key outcomes following percutaneous 60-day PNS for chronic shoulder pain demonstrates durability extending up to 5 years post treatment. The high rate of surgery avoidance and low progression to additional major interventions suggests potential healthcare economic impact, particularly given the rising costs and incidence of shoulder surgeries. These findings, together with recent economic model analyses, support 60-day PNS as clinically effective and potentially economically advantageous approach for appropriate patients with chronic shoulder pain that may help reduce the need for more invasive and costly interventions while maintaining long-term therapeutic benefit.

Author Contributions

Kevin E. Vorenkamp—data analysis and interpretation, drafting the manuscript, review and revision of final version of the manuscript; Gemayel Lee—data analysis and interpretation, drafting the manuscript, review and revision of final version of the manuscript; Denise D. Lester—data analysis and interpretation, drafting the manuscript, review and revision of final version of the manuscript; Chaitanya Konda—data analysis and interpretation, drafting the manuscript, review and revision of final version of the manuscript; Steven P. Cohen—data analysis and interpretation, drafting the manuscript, review and revision of final version of the manuscript; Nate D. Crosby—study conception and design, data collection, analysis and interpretation, drafting the manuscript, review and revision of final version of the manuscript; Joseph W. Boggs– study conception and design, data analysis and interpretation, drafting the manuscript, review and revision of final version of the manuscript;

Funding

The study and this journals Rapid Service Fee, was supported by SPR Therapeutics.

Data Availability

The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.

Declarations

Conflict of Interest

Kevin E. Vorenkamp has nothing to disclose relevant to the present work. Gemayel Lee is a consultant to SPR Therapeutics. Denise D. Lester has received research funding paid to her institution by SPR Therapeutics unrelated to the present work. Chaitanya Konda has nothing to disclose relevant to the present work. Steven P. Cohen is a consultant to SPR Therapeutics. Nate D. Crosby and Joseph W. Boggs are employees of and hold stock options in SPR Therapeutics.

Ethical Approval

The study was approved by the WIRB-Copernicus Group Institutional Review Board (WCG-IRB, #20242073) with a waiver of documentation of informed consent. The survey included a consent agreement that acknowledged the use of de-identified survey data for research purposes. The study was performed in accordance with relevant portions of the Declaration of Helsinki.