Introduction After spinal and knee pain, shoulder pain is estimated to be the third most common type of musculoskeletal pain, causing considerable psychosocial impact if progressing to the chronic phase. While majority of patients with shoulder pain recover within few months, over 40% of patients have persisting symptoms after 12 months. Establishing a treatment strategy for shoulder pain can be challenging, as the effectiveness of many treatment options is unclear. Non-surgical strategies are preferred in the first-line management, with physiotherapy being of the treatment of choice in the majority of cases. Physiotherapy, pain medication and corticosteroid injections (CSI) are used but the effectiveness of these interventions may be insufficient. Corticosteroid injections are often used in treatment of shoulder pain, though there is no clear evidence of long-term benefit. It has been reported that CSI might lead to adverse events such as tendon degeneration, cutaneous atrophy or infection. In addition, CSI can cause systemic side effects including changes in the hypothalamic-pituitary-adrenal axis function and elevated blood glucose levels. Therefore, safer pain management options with more long-lasting pain relief are sought. The suprascapular nerve derives from the ventral rami of cervical spinal nerves C4, C5, and C6 and arises from the upper trunk of the brachial plexus, contributes approximately 70% of the sensory innervation to the shoulder joint. Suprascapular nerve blocks have been used to manage acute and chronic shoulder pain, although the efficacy of treatment alters in different studies and when compared to other treatment options. The short duration of action of local anesthetics raises the question of their efficacy in the management of chronic shoulder conditions. In addition to SSNB, pulsed radiofrequency stimulation (pRF) has also been researched for its potentially greater and longer-lasting outcomes when comparing to local anesthetics. There has been limited numbers of reviews specifically investigating the usefulness of SSNB for the treatment of chronic shoulder pain. Liu et al. concluded in their review pRF treatment to result in good efficiency in shoulder patients with no significant complications reported. The pain relief could last several months. Only few case reports have been made on pRF treatment of the glenohumeral joint. Considering the adverse effects of corticosteroids, SSNB with local anesthetics could be regarded as a potential alternative for pain relief in patients who have adhesive capsulitis. Our earlier results suggested additional therapeutic benefit obtained when pRF for both suprascapular nerve and shoulder joint was performed in addition to physiotherapy.

The aim of this study was to compare whether pRF treatment of both glenohumeral joint and suprascapular nerve provided additional clinical benefits compared to suprascapular nerve block or pRF treatment of suprascapular nerve only. The rehabilitation included also individual functional training and treatment as recommended by the national task group.

Method This randomized controlled trial will follow the Consolidated Standards of Reporting Trials Statement; it will be performed at Central Hospital in Satakunta, Pori, Finland. The study has been approved by the local Research Ethics Committee (SS/1184/13.01/2018). The sample size estimate was obtained to detect differences between the treatment groups in relation to the primary outcome of the study after the intervention. Kukkonen's et al. study estimated the clinically important minimal difference in CM score in 10.4 points in patients with rotator cuff rupture after 3 months of surgical treatment by the arthroscopic method. The estimated sample size of 45 patients per group, total of 135patients, would reach 90% power to detect a 10.4 difference between the groups in the SPADI instrument follow-up score with a standard deviation of up to 15 points with a significance level of 5% using a t-Student test. Predicting a loss of around 10% at 6 months follow-up, we aim to recruit 50 patients per group. The placebo response is usually estimated as high as 30%. Using calculation of difference between proportions, the sample size was estimated as 50 patients total. Randomization 1:1:1 is performed. Patients will be consecutively allocated to one of three proposed treatment methods. The software R was used to generate a randomization list, considering 150 patients included in the study and the same probability of allocation for methods of pain treatment intervention. Patients with shoulder pain \> 3 months duration, clinical and imaging confirmation of adhesive capsulitis, tendinosis, arthritis, rotator cuff or capsular tears are eligible for participation. Failure of conservative medical therapy is documented. Exclusion criteria comprised refusal to participate, extrinsic source of shoulder pain (e.g., cervical radiculopathy) and pain related to bony fracture. All patients are at first evaluated by specialist in physical medicine and rehabilitation who use ultrasound and clinical examination to estimate shoulder function. Patients who have more specific shoulder dysfunction based on subjective symptoms and clinical evaluation are asked to participate this intervention study. Of totally around 300 consecutive patients who receive pRF on the suprascapular nerve and shoulder joint, 150 consecutive patients are estimated voluntarily participate the study. Primary outcomes, such as Shoulder Pain and Disability Index ,15D self-administered measure of health-related quality of life and working ability are measured. This study is also part of the quality register study of the unit. Our standardized patient surveys cover demographic data, level of education, work status and future outlook, pain intensity, psychological factors, measurements of activity/participation and health-related quality of life (MPI, HAD SF-36, EQ-5D,CPAQ;Tampa,ISI). Those patients, who report no pain relief at 2-month follow-up and are dissatisfied, have an option to undergo pRF procedure any time after the first follow-up visit. Patients are able to dropout from the study any time. The randomization will be carried out by assisting nurse and delivered in sealed envelopes marked SSPS "subscapularis" (suprascapular nerve block), " pRF suprascapular" (pRF stimulation of suprascapular nerve) or "suprascapualar + joint" (pRF stimulation both suprascapular nerve and shoulder joint). Patient will be blinded. Two operators to minimize individual technical differences perform all procedures. Physician who did not treat the patient primarily and did not know which treatment patient received will conduct follow up estimation (pretreatment, 10 and 30 weeks after intervention). The groups will be compared according to the presence of categorical clinical outcomes by Chi-square or Fisher's exact tests, depending on the distribution observed after data collection. The analyzes will be performed with the aid of the SPSS program, considering a significance level of 5%. Demographic variables will be compared using a t-test or chi-squared test for continuous and categorical variables, respectively. Repeated measures ANOVA will be utilized for the primary outcome of Pain NRS and the secondary outcomes of the SPADI and AROM. Planned contrasts examining the linear trend effect of each group's scores over time were also included in the analysis. For the HRQoL scale, paired-sample t-tests will be conducted to compare groups, at each time.

Interventions All patients will be offered conservative treatment including pharmacotherapy (opioid analgesics, NSAIDs, paracetamol, adjuvant medication) and physiotherapy. Physiotherapy program based on manual therapy intervention focus on increasing function and pain control. Physical training is largely based on specific movements supervised by qualified physiotherapists. The emphasis is on individual training program, and on learning a functional use of the arm. PRF treatment and nerve block will be performed under ultrasound guidance. First, the suprascapular notch is identified using ultrasound with the patient in the sitting position, shoulders relaxed and forearms placed on the thighs. The puncture site is located on the line dividing the upper-outer quadrant of the scapula approximately 2.5 cm from the top. Following the puncture, an isolated radiofrequency 23-G 60 mm needle with a 5 mm active tip (Top Neuropole needle XE 60 mm 23G) is introduced perpendicularly to the skin in all planes. Selective stimulation of motor fibers (50 Hz) commenced after the needle tip had penetrated into the suprascapular notch. Motoric response or paresthesia at a voltage between 0.3 and 0.5 V is sought.

Envelopes marked SSPS "supraspinatus" will result in injection of 1 ml Lidocaine (10%) and "pRF suprascapularis" or "suprascapualris+joint" result in pRF stimulation, a 4-minute cycle of pRF with STP (Sluijter Teixeira Pulsed Poisson) program (TOP Lesion Generator TLG-10, Equip Medikey BV, The Netherlands) will be performed. One ml Lidocaine (10%) will be injected at the end of therapy since irritation of nerve fibers by the electrical field (without thermolesion) has been described as occurring frequently. Shoulder joint RF stimulation procedure use posterior approach. The sulcus between the head of the humerus and acromion is identified by ultrasound. The needle is inserted 2-3cm inferior and medial to the posterolateral corner of the acromion and directed anteriorly towards the coracoid process. An isolated radiofrequency 23-G 60 mm needle with a 5 mm active tip (Top Neuropole needle XE 60 mm 23G) will be introduced perpendicularly to the skin in all planes completely into the joint. First, 0,1-0,2 ml Lidocaine (10%) will be injected after puncture of skin and after pRF treatment 0,8 ml in the shoulder joint. Joint capsule stimulation, a 4 minute cycle of pRF with STP program is performed. Pain VAS, glenohumeral joint active range of motion and any complications will be recorded before discharge. The patients receive contact details of an available nurse prior to discharge. Next week after the RF-stimulation, we recommend restart of physiotherapy intervention focused on increasing function and pain control. Average rehabilitation time is calculated to be three months and on average patients have six consultations (1-12) in 6 months.

MEASUREMENTS Prior to the first MD appointment, participants are asked to compleat questionnaire. At the first appointment, using standardized clinical data forms; MD record the history of the participant's shoulder problem and clinical examination findings. In addition to active and passive ranges of motion, Visual Analogue Scale (VAS) and Shoulder Pain and Disability Index (SPADI), are recorded to assess shoulder function. The SPADI is a patient administered questionnaire consisting of 13 items divided into two subscales: pain (5 questions) and disability (8 questions). The pain and disability subscales are scored separately and then calculated into a total SPADI score, with higher scores demonstrating increased pain and disability. We also included 15D self-administered measure of health-related quality of life (HRQoL). 15D is a generic, comprehensive, 15-dimensional, standardized, self-administered measure of health-related quality of life (HRQoL) and it can be used as a profile and single index score measure. The single index score (15D score) on a 0-1 scale, representing the overall HRQoL, is calculated. Participants will be followed during 6 months, and subjective and objective outcome variables will be recorded for primary outcome instruments at 2 and 6 months and secondary outcome instruments at 6 months follow-up.