Effect of Minimally Invasive Pain Intervention in Frozen Shoulder Patients: A Cross-Sectional Study.

BACKGROUND: Adhesive capsulitis or frozen shoulder (FS) is the second most common disorder accounts for 15%-30% shoulder pain and functional disability. Suprascapular nerve (SSN) interventions with corticosteroid alone have shown limited duration efficacy, adding pulsed radiofrequency (PRF) provides long-term relief. AIMS AND
OBJECTIVE: We aimed to analyze the efficacy of SSN intervention on pain relief and range of mobility in patients with FS. SETTINGS AND
DESIGN: This is a cross-sectional study of 37 patients of FS who underwent SSN interventions in a dedicated pain medicine unit of the department of anesthesiology.
MATERIALS AND METHODS: Thirty-seven patients, who underwent SSN interventions for FS and followed for 6 months, were included in this study. Pain (Visual Analog Scale [VAS]), range of motion (ROM) (17), and Oxford 12 point Shoulder Score (OSS) for functional outcomes were recorded. In the final analysis, two subsets of patients who underwent SSN steroid injection or SSN PRF plus steroid were found and compared using Student's t-test paired and independent with P < 0.05 considered significant at 95% confidence interval.
RESULTS: The patient population was demographically comparable. Mean VAS score and ROM improved at 1, 3, and 6 months to statistically significant. On comparing the subgroups, the VAS score and OSS in both the SI and PRF groups were significantly improved, but the PRF group showed highly significant improvement, showing better and sustained improvement in the PRF group.
CONCLUSION: PRF with steroid injection of the SSN provides better and long-lasting relief from pain and improved mobility in FS patients in comparison to steroid alone. Copyright:

INTRODUCTION

Adhesive capsulitis commonly called frozen shoulder (FS) is the second most common musculoskeletal disorder in adults accounting for 15%–30% shoulder pain.[1] FS is a progressive shoulder disorder causing severe pain with loss of movement and functional disability.[23] In elderly patients with history of diabetes mellitus, arthritis, and degenerative disease, the disease is more pronounced resulting in chronic pain which is difficult to treat.[4] The treatment options vary from conservative medical treatment to minimally invasive interventional pain procedures to extensive shoulder surgery.[567]

Shoulder joint is innervated by three nerves: suprascapular nerve (SSN), axillary nerve, and lateral pectoral nerve. SSN gives sensory supply to 70% of the shoulder joint, superior, and posterosuperior regions of the shoulder joint and capsule and the acromioclavicular joint.[5] In addition, it supplies motor branches to supraspinatus and infraspinatus muscles.[6] Thus, SSN intervention has shown some promise as an alternative treatment for patients with shoulder pain, in addition to medical treatment and physiotherapy.[7]

SSN interventions using local anesthetics and steroids have been successful in treating chronic shoulder pain from degenerative disorders and inflammatory diseases.[89] However, the effects of SSN intervention using corticosteroids alone have shown limited duration efficacy.[10]

The idea of pulsed radiofrequency (PRF) was spawned after a chance meeting in 1993, and the first PRF procedure, on a lumbar dorsal root ganglion, took place on February 1, 1996.[11] Pulsed mode radiofrequency (PRF) lesioning is a nonneuroablative, i.e., neuromodulatory, method for pain relief without evidence of neural damage.[121314] Very few case studies have been reported for PRF neuromodulation to the SSN which support its long-term efficacy in pain relief.[1516] The rationale behind this cross-sectional study is to analyze SSN minimally invasive pain intervention in patients of FS.

Aims and objectives

We aimed to analyze the efficacy of SSN interventions in patients with FS on pain relief (Visual Analog Score), range of motion (ROM), and functional improvement assessment using Oxford Shoulder Score (OSS).

MATERIALS AND METHODS

Study design

This study was conducted at a tertiary care 1100-bedded multispecialty teaching hospital. A cross-sectional study was conducted in the pain medicine unit of the department of Anesthesiology. Before the start of the study, the ethical clearance was taken from the institutional ethics committee (IEC110/20), and after necessary modifications, the sample size was calculated. The pain medicine operation theater data were searched and analyzed for all patients who underwent SSN intervention for chronic shoulder pain, from July 2017 to July 2019, for this study. Our study follows the Helsinki Declaration. Written informed consent was obtained from the study participants.

Inclusion criteria

Patients suffering from chronic shoulder pain, not responding to conservative treatment for more than 6 weeks, and undergoing SSN pain intervention were included in this study.

Exclusion criteria

Patients with pain due to secondary causes, for example, acute trauma, fractures, bony deformity, glenohumeral joint pathology, acromioclavicular joint pathology, and rotator cuff disorder, and patients with known contraindications for minimally invasive pain interventions, for example, bleeding disorder, infection, and chronic obstructive pulmonary disease, were excluded from this study. Patients with allergy to drugs, pregnant patients, and patients with known coagulopathy were also excluded. Patients who did not give consent were also excluded.

After following all inclusion and exclusion criteria, 37 patients were found to be eligible for the study and their data were used for final statistical analysis. Patients’ details were recorded including epidemiological parameters, clinical parameters, and preoperative pain by Visual Analog Scale (VAS), ROM,[17] and Oxford 12-point Shoulder Score (OSS).[18] All patients included in the study were followed for 6 months. All patients were taken after written consent and preoperative workup.

In the final analysis, two subsets of patients who underwent either SSN steroid injection or SSN PRF treatment were compared.

Suprascapular nerve intervention technique

All cases were done with a patient in prone position with affected arm on the side of the patient. A C-arm fluoroscope with 15°–20° cranial tilt and 10°–15° ipsilateral oblique tilt was used to visualize the suprascapular notch [Figures 1 and 2]. Then, a 22G, 10 cm RF cannulae (SMK RF Cannulae) was used to enter the suprascapular notch. Sensory stimulation at 50 Hz and motor stimulation at 2 Hz were used to localize the SSN. After negative aspiration, an injection of 8 ml of 0.25% bupivacaine plus 40 mg injection triamcinolone or a long duration pulsed radiofrequency treatment was done at 2 Hz with a maximum temperature of 42°C for 480 s was done.[1519] All patients were observed for 2 h and then discharged with instructions to do ROM exercises of the treated shoulder joint.

Figure 1

Needle in suprascapular notch

Figure 2

Dye filling the suprascapular notch

Data and statistical analysis

The internal consistency of any identified, and original, subscales was tested with Cronbach's alpha. Alpha values in the range of 0.80–0.90 were considered optimal, with a minimum alpha of 0.70 being necessary to claim internal consistency. The standard error of mean was calculated as the standard deviation multiplied by the square root of one minus the intraclass correlation coefficient. Chi-square test was utilized for demographic data, and both paired Student's t-test and independent t-test were used to compare pain scores in those with a good or poor recovery. The association between the change in pain VAS score and the Oxford Shoulder Score was quantified by the Spearman rank correlation coefficient (r). We determined test–retest reliability in those who had rated their pain state as unchanged or almost the same (global rating scores of 1, 0 or 1) using the intraclass correlation coefficient. A significant difference was accepted at P < 0.05. All statistical analyses were performed using Statistical Package for Social Sciences (SPSS)-21, Chicago, Illinois, USA for data analysis. P < 0.05 considered with 95% confidence interval in the study.

RESULTS AND OBSERVATIONS

The demographic data of our patients’ population has shown homogeneity in both the subgroups. The mean age of our patients was 55 + 10.55 years. There was a female preponderance in our patient population (total patients 37, females 25 [67.6%] and males 12 [32.4%]). Seventeen (45.9%) out of 37 patients underwent steroid injection of SSN and 20 (54.1%) underwent PRF treatment in addition to steroid injection [Figure 3].χ2 = 17.108; P = 0.705

Figure 3

Representation of gender distribution of the study population and the procedure involved. SI: Steroid injection, PRF: Pulsed radiofrequency

Preintervention, the mean VAS score was 8.89 ± 0.699 (P = 0.434), which improved at 1, 3, and 6 months to 4 ± 1.027 (P = 0.036), 3.49 ± 1.805 (P = 0.014), and 3.32 ± 2.18 (P = 0.0012), respectively, in all patients, which was statistically significant [Table 1]. Preintervention, ROM abduction and extension were 103.65° ± 11.88° and 29.59° ± 7.5°, respectively. Postintervention, abduction showed improvement at 1, 3, and 6 months to 120.95 ± 13.06 (P = 0.026), 128.65 ± 12.83 (P = 0.056), and 134.86 ± 13.30 (P = 0.001) and extension showed improvement at 3 and 6 months to 37.57 ± 6.37 (P = 0.023, S) and 37.97 ± 6.71 (P = 0.013, S), respectively, in all patients [Tables 2 and 3]. This shows that pain interventions are effective in improvement in ROM.

Table 1

Clinical outcomes for Visual Analog Scale scores preintervention and postintervention (Student’s t-test)

VAS score	Mean±SD	SEM	t test	df	P
VAS preintervention	8.89±0.699	0.115	77.422	36	0.434 (NS)
VAS 1 month	4±1.027	0.169	23.682		0.036 (S)
VAS 3 months	3.49±1.805	0.297	11.752		0.014 (S)
VAS 6 months	3.32 ±2.18	0.359	9.248		<0.001 (HS)

VAS=Visual Analog Scale, SEM=Standard error of mean, df=Degree of freedom, NS=Nonsignificant, S=Significant, HS=Highly significant, SD=Standard deviation

Table 2

Clinical outcomes with range of motion in abduction

Range of motion	Mean±SD (°)	SEM	t test	df	Mean difference	P
Preintervention abduction	103.65±11.88	1.95	53.06	36	103.64	0.462 (NS)
Abduction 1 month	120.95±13.06	2.15	56.32		120.94	0.026 (S)
Abduction 3 months	128.65±12.83	2.23	62.95		129.34	0.048 (S)
Abduction 6 months	134.86±13.30	2.18	61.65		134.86	<0.001 (HS)

SEM=Standard error of mean, df=Degree of freedom, NS=Nonsignificant, S=Significant, HS=Highly significant, SD=Standard deviation

Table 3

Clinical outcomes with range of motion in extension

Range of motion	Mean±SD	SEM	t-test	df	Mean difference	P
Preintervention extension	29.59±7.58	1.24	23.746	36	29.59	0.532 (NS)
Extension 1 month	34.32±7.46	1.23	27.95		34.32	0.063 (NS)
Extension 3 months	37.57±6.73	1.90	33.94		37.56	0.023 (S)
Extension 6 months	37.97±6.71	1.104	34.40		37.97	0.013 (S)

SEM=Standard error of mean, df=Degree of freedom, NS=Nonsignificant, S=Significant, HS=Highly significant, SD=Standard deviation

On comparison between the subgroups, the VAS score in the SI and PRF groups was significantly improved at 1 month (4.35 ± 0.786, P = 0.014 and 3.70 ± 1.129, 0.047); at 3 and 6 months, the PRF group showed highly significant (2.55 ± 1.36, P = 0.001 and 1.95 ± 1.23, P = 0.001) improvement in VAS scores while the SI group showed significant improvement (4.59 ± 1.66, P = 0.623 and 4.94 ± 1.952, P = 0.040), showing better and sustained improvement in the PRF group. The preintervention Oxford Shoulder Score in the SI and PRF groups was 12.65 ± 2.26 and 12.15 ± 2.134, respectively, which improved to statistically significant values at 1 and 6 months 34.06 ± 3.09, P = 0.031, S and 30.35 ± 6.09, P = 0.011, S (SI group) and 35.10 ± 3.024 P = 0.021, S and 40.05 ± 4.96 P = 0.011, S (PRF group) [Table 4 and Figure 4], showing functional restoration in all patients who underwent pain interventions.

Table 4

The comparison of Visual Analog Scale score and Oxford Shoulder Score with respect to steroid injection and pulse radiofrequency groups

VAS	n	Mean±SD	SEM	T test value	df	Mean difference	P
VAS preoperative	17				35	0.091	0.073 (NS)
SI group	20	8.94±0.556	0.135	0.391
PRF group		8.85±0.813	0.182	0.69
VAS 1 month						0.653	0.048 (S)
SI group		4.35±0.786	0.191	2.006
PRF group		3.70±1.129	0.252	2.06
VAS 3 months						2.122	0.002 (S)
SI group		4.59±1.661	0.403`	3.724
PRF group		2.55±1.36	0.303	4.04
VAS 6 months						2.991	0.012 (S)
SI group		4.94±1.952	0.473	5.658
PRF group		1.95±1.23	0.276	5.25
Oxford Shoulder Score in steroid injection and pulse radiofrequency groups
OSS	n	Mean±SD	SEM	t	df	Mean difference	P
OSS preoperative	17				35	0.497	0.462 (NS)
SI group	20	12.65±2.26	0.549	0.687
PRF group		12.15±2.134	0.477	0.684
OSS 1 month						1.041	0.031 (S)
SI group		34.06±3.09	0.750	1.033
PRF group		35.10±3.024	0.676	1.031
OSS 6 months						9.697	0.011 (S)
SI group		30.35±6.09	1.478	5.334
PRF group		40.05±4.96	1.111	5.246

SEM=Standard error of mean, df=Degree of freedom, NS=Nonsignificant, S=Significant, HS=Highly significant, SI group=Steroid injection, PRF group=Pulse radiofrequency, SD=Standard deviation, OSS=Oxford 12-point Shoulder Score

Figure 4

The comparison of Visual Analog Scale score and Oxford Shoulder Score

Inference

Total population n (%) = 37 (100%)

Total number of females = n1 (%) = 25 (67.6%)

Total number of males = n2 (%) = 12 (32.4%).

Procedure

SI = 17 (45.9%)

PRF = 20 (54.1%).

DISCUSSION

FS patients usually present in the sixth decade of life and onset before the age of 40 is very uncommon. The peak age is 56 years, and the condition occurs slightly more in women than men. The condition affects both sides equally, but nondominant shoulder is slightly more likely to be affected. However, sequential bilateral occurrence may be found in up to 50% of patients.[20212223]

Reeves[24] in a prospective study of 41 patients with 5–10-year follow-up found that only 39% of patients had full recovery. This long period of pain and disability deprives the patients of their routine activities of daily living and also poses occupational difficulties, thus adversely affecting their quality of life (QOL).

FS can be classified either as primary (idiopathic) or secondary (associated with systemic diseases). The most common association is with diabetes mellitus, and the incidence is reported to be 10%–36%;[23] in these patients, it is often more severe and more resistant to treatment.[25] Other associated causes include thyroid disease, adrenal disease, cardiopulmonary disease, hyperlipidemia, and patients with stroke due to immobilization.[20]

The clinical spectrum of FS has been divided into three phases: painful freezing phase lasts up to 2–9 months with pain and stiffness around the shoulder with no history of injury. Pain is a constant and nagging type and worse at night, with little response to nonsteroidal anti-inflammatory drugs (NSAIDs). Adhesive phase is the middle phase which lasts from 4 to 12 months. In this phase, pain gradually subsides, but stiffness remains. Pain is apparent only at the extremes of movement. Following the adhesive phase, resolution phase starts and may last from 12 to 42 months. During this phase, spontaneous improvement in the range of movement occurs. The mean duration from the onset of FS to the greatest resolution is usually over 30 months.[2024]

The etiology of FS remains unclear. The disease process particularly affects the anterosuperior joint capsule and the coracohumeral ligament.[26] Bunker[27] studied histological samples of capsular tissue from patients with FS and found a pathological picture comparable to Dupuytren's disease.

Management

The goal of treatment of FS is to restore the shoulder to a painless and functional joint. No definitive treatment strategy has been established, and many different management strategies are being used. Common conservative treatments include oral medication, physical therapy, exercise, steroid injection, and hydrodilatation.

Physiotherapy

Physiotherapy is widely accepted as an initial treatment in many shoulder conditions including FS. Physiotherapy forms the mainstay of early and mid-stage disease. In general, physiotherapy is simultaneously combined with other treatment modalities as an adjunctive intervention; a Cochrane study concludes that there is little overall evidence to support physiotherapy alone in the treatment of FS.[28] Physical therapy can be combined with ultrasonic therapy, transcutaneous electrical nerve stimulation, short-wave therapy, low-level laser therapy, hydrotherapy, and minimally invasive pain interventions as SSN PRF.

Pharmacological therapy, including NSAIDs and systemic or intra-articular corticosteroids, provides symptomatic management and serves as an adjunct to physical therapy. Pain management is a key feature as it allows patients to tolerate physical therapy to improve ROM. NSAIDs are generally recommended for short-term pain relief. The role of oral corticosteroids has been examined in multiple studies. Most of these demonstrate a short-term benefit with a reduction in pain, especially during the early stages of FS.[2930]

SSN minimally invasive percutaneous intervention with local anesthetic agent and small doses of steroids and PRF treatment are increasingly used in the multimodal treatment of FS. They are safe and well-tolerated treatment option and effective in reducing pain severity and functional disability and hence improve QOL of the patients with FS.[31] Pulsed mode radiofrequency (PRF) lesioning is a nonneuroablative, i.e., neuromodulatory, method for pain relief, and can relieve pain without evidence of neural damage.

In patients with failed conservative care including poor response to minimally invasive pain interventions like SSN-PRF, surgical interventions such as manipulation under anesthesia and arthroscopic capsular release under general anesthesia can be employed.

The aim of our retrospective study was to evaluate the use of minimally invasive and percutaneous pain interventions (SSN steroid injection and SSN PRF) in the management of FS.

Data from the pain medicine operation theater were taken out and analyzed from June 2017 to June 2019. Total 37 patients underwent minimally invasive pain intervention for FS during this period and were included in the final analysis. Our patient population shows female preponderance, similar to the studies by Neviaser and Neviaser,[19] Lloyd-Roberts and French,[32] and Kothari et al.[33] Out of these 37 patients, 17 patients received steroid injection and 20 patients were given PRF with steroid.

The VAS pain score shows a statistically significant improvement from preoperative to 1 month (P = 0.036) and 3 months (P = 0.014) and a highly significant difference at 6 months (P = 0012) in all patients. On comparing the subgroups, the VAS improved to highly significant values at 6 months in the PRF group showing PRF to be better in pain relief in comparison to the steroid group [Table 2]. Shanahan et al.[2] and Shah and Racz[1134] also concluded in their study that PRF lesioning of the SSN is effective for relieving various acute and chronic shoulder pain syndromes.

The clinical outcomes with ROM in abduction in our study showed a consistent and significant improvement at various time intervals and extension also showed a significant improvement at 3- and 6-month duration in all patients. This suggests that there is a remarkable improvement in abduction ROM [Tables 2 and 3]. Our results were similar to studies done by Liliang et al.,[3] and Snidvongs and Mehta[35] have also shown in their studies that PRF of SSN provides clinical improvement in FS patients.

The 12-point Oxford Shoulder Score preintervention was statistically nonsignificant in both the groups. Postintervention, the OSS shows a significant improvement in the SI and PRF groups showing improvement in functional capacity and QOL which was more pronounced and long lasting in the PRF group. Jang et al.[6] also reported that PRF neuromodulation of the SSN is an effective treatment for chronic shoulder pain, and the effect was sustained over a relatively long period pain with improvement in OSS with an increase in functional capacity of patients.

CONCLUSION

This study highlights the growing importance of PRF procedure in chronic shoulder pain, especially in clinical scenarios where steroid injection procedure is not long lasting in pain relief, PRF added to significant improvement in range of shoulder motion, pain, and functional capacity than steroid alone injection procedure.

Thus, the study indicates that the application of PRF treatment with steroid injection of the SSN provides better and long-lasting relief from pain and mobility in comparison to steroid injection alone.

Limitation

Our study has some limitations. First, although the VAS and mobility of the shoulder are proven tools for the quantification of pain, they are subjective outcome measures because they according to individual persons. Second, the small sample size limits the strength and generalizability of our observations.

Ethical approval

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 (in case humans are involved).

Key points (High light of article)

Shoulder pain treatment in frozen shoulder or adhesive capsulitis

Role of minimally invasive intervention in frozen shoulder use of steroid, physiotherapy, and pulsed radiofrequency

Role of radiofrequency in suprascapular nerve intervention.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.