Table 1.

Characteristics of the Studies Included

Author, Year, Study Design	Participants (n), Inclusion/exclusion criteria	Psychological Factors Investigated	Group of Intervention (GI) Group of Control (GC)	Outcome Measures, Units, Time of Follow-Up
Bagheri et al., 2016 Cross-sectional study Level of evidence: IV	n = 120 (mean age 52 y; 37 men, 83 woman) Inclusion criteria: •Idiopathic FS phase-II •Shoulder pain <3 months Exclusion criteria: •History of rotator cuff tear •Previous shoulder surgery or fracture •Psychosis	Anxiety; depression	//	DASH score, VAS score, SF-36 (PCS component), SF-36 (MCS component), HAQ, HDQ, at baseline
De Baets et al., 2020 Cross-sectional study Level of evidence: IV	n = 85 (mean age 55.2 y; 26 men, 59 woman) Inclusion criteria: •unilateral FSCS •passive ROM restriction ≥25% in at least 2 directions compared to the unaffected side •ER≥50% compared to the unaffected side. •Pain and restricted ROM ≥ 2 months •gradual onset of pain and stiffness. •be able to fill in questionnaires in Dutch. Exclusion criteria: •surgery procedure for FS •systemic or neurological disease	Pain-related fear, pain catastrophizing, pain self-efficacy	//	DASH questionnaire, TSK, PCS∗, PSEQ, NPRS at baseline
Ding et al., 2014 Cross-sectional study Level of evidence: IV	n = 254 (mean age: 52.16 ± 6.16 y; 46 men, 78 woman) Inclusion criteria: •Insidious onset and last ≥3 months •night pain •tenderness around the joint capsule •ER restriction •normal radiographic or just a little joint fluid in magnetic resonance imaging. Exclusion criteria: •concomitant disorders that could influence disease activity or psychological status •secondary FS, trauma, arthritis •the relapse of FS or both shoulders affected •cervical spondylosis	Anxiety; depression	GI: n = 124 FSCS GC:n = 130 healthy people	VAS, sleep disturbances, SST, SPADI, ROM, HAQ, HADS-D, HADS-A at baseline
Ebrahimzadeh et al., 2019 Cross-sectional study Level of evidence: IV	n = 120 (mean age 52 SD 17 y; 37 men, 83 women) Inclusion criteria: •FSCS •phase II FS •shoulder pain ≥ 3 months Exclusion criteria: •history of psychosis •diagnosed rotator cuff tear •previous shoulder surgery or fracture	Anxiety; depression	//	VAS, DASH, HADS-D, HADS-A at baseline
Toprak et al., 2018 Cross-sectional study Level of evidence: IV	n = 148 (25-65 years old) Inclusion criteria: •Age range 25–65 y •insidious onset of pain and stiffness with a clinical reduction in ROM, principally ER reduction >50% no radiological abnormalities •presence of pain Exclusion criteria: •history of shoulder surgery or trauma •other shoulder pathology •history of psychiatric disorders •local corticosteroid injection or any physiotherapy intervention to the affected shoulder within the last 6 months •cerebrovascular accident affecting the shoulder •concomitant disorders unwillingness to participate in the study	Anxiety; depression	GI: n = 76 FSCS patients (mean age 59.32 ± SD 13.91 y; 21 men, 55 women) GC: n=72 healthy patients (mean age 58.50 ± SD 8.74 y; 18 men, 54 women)	VAS, BDI, BAI, WHO-QoL bref, PSQI
De Baets et al., 2020 Prognostic study Level of evidence: IV	n = 20 (mean age 56 ± 8 y, 6 men, 14 women) Inclusion criteria: •Adults with unilateral, FSCS •passive ROM restriction≥25% in minimum 2 directions •unaffected shoulder •ER restriction of at least 50% •pain and restricted ROM last≥2 months •A gradual onset of the perceived pain and stiffness •Be able to fill in questionnaires in Dutch Exclusion criteria: •Previous surgical procedure for FS •Partial/full thickness rotator cuff tear seen on magnetic resonance arthrogarphy •Systemic, neurological, or psychiatric disease	Pain-related fear, pain catastrophizing	patients were treated with Ultrasound-guided intra-articular corticosteroid injections (80 mg Depomedrol and 6 cc Lidocaine HCl 1%) via posterior at baseline, 6 and 12 weeks; patient education (manual), joint mobilizations, mobility and stretching exercises, home-management training, and neuromuscular training	Outcome measures: DASH, GH ABD and ER ROM (goniometry), NRS-stiffness, NRS-pain, TSK, PCS∗, CHL thickness, IGR perimeter Follow-up: baseline and 4 months

ABD, abduction; BAI, Beck Anxiety Inventory; BDI, Beck Depression Inventory; CHL, coraco-humeral ligament; DASH, Disability of the Arm, Shoulder and Hand; ER, external rotation; FS, frozen shoulder; FSCS, Frozen Shoulder Contracture Syndrome; GH, glenohumeral; HADS-A, Hamilton Anxiety and depression Scale-Anxiety; HADS-D, Hamilton Anxiety and depression Scale-Depression; HAQ, Hamilton Anxiety Questionnaire; HDQ, Hamilton Depression Questionnnaire; IGR, inferior glenohumeral recess perimeter; IR, internal rotation; MCS, Mental Component Summary; NPRS, Numeric Pain Rating Scale; NRS, Numeric Rating Scale; PCS, Physical Component Summary; PCS∗, Pain Catastrophyzing Scale; PSEQ, Pain Self-Efficacy Questionnaire; PSQI, Pittsburgh Sleep Quality Index; ROM, range of movement; SF-36, Health Survey Short Form, 36 question; SPADI, Shoulder Pain and Disability Index; SST, Simple Shouder Test; TSK, Tampa Scale of Kinesiophobia; VAS, visual analog scale; WHO-QoL bref, World Health Organization Quality of Life Scale short form; Y, years.