Is There a Genetic Predisposition to Frozen Shoulder?: A Systematic Review and Meta-Analysis

AAOS 2024 best paper in the shoulder and elbow classification: watchful waiting provides higher value with similar functional outcomes to physical therapy for frozen shoulder: a prospective randomized controlled trial

BACKGROUND

Physical therapy remains a ubiquitous treatment modality for the management of frozen shoulder (adhesive capsulitis) despite limited high-level evidence supporting its use. Leveraging patient-reported outcome measures (PROMs) and healthcare costs, this study compared patient outcomes and value achieved through watchful waiting (WW) vs. physical therapy (PT) for conservative management of frozen shoulder.

METHODS

Patients in this prospective, parallel randomized controlled trial who were diagnosed with frozen shoulder were randomized 1:1 to WW or PT. All patients were offered therapeutic, intra-articular corticosteroid injections (CSIs). The primary outcome was the American Shoulder and Elbow Surgeons Score. Secondary outcomes included patient value (ie, 12-month American Shoulder and Elbow Surgeons score divided by healthcare costs), the Disabilities of the Arm, Shoulder, and Hand questionnaire, and Visual Analog Scale pain. Due to the confidentiality of internal hospital data, all economic outcomes were divided by an undisclosed constant to set the normalized study mean for direct costs to 1000; similarly, patient value was normalized to set the study mean to 100. Outcomes were assessed at baseline, 6 weeks, 3 months, 6 months, and 12 months using mixed-effects models, with sensitivity analyses adjusting for nonlinear improvement trajectories and CSIs.

RESULTS

Between November 2014 and November 2022, 175 patients were screened, 61 of whom (34.9%) were randomized to WW (31 patients) or PT (30 patients). Forty-seven patients (96%) received at least one CSI, with no significant difference in CSI administration between cohorts (P = .29). Relative to baseline scores, patients from both cohorts improved significantly at each time point for all PROMs (P < .05 for all), with no significant differences in PROMs between groups at any time point (P > .05 for all). However, compared to those assigned WW, patients randomized to PT incurred 10.0× higher costs (normalized mean difference: 1636; 95% CI: 967, 2304; P < .001) and achieved only 16.9% of the patient value (normalized mean difference: -147.0; 95% CI: -207.5, -86.5; P < .001). These results held across all sensitivity analyses.

CONCLUSION

Relative to WW, patients randomized to PT reported similar PROMs but incurred significantly higher direct costs (10.0×) and imposed a greater economic burden on the healthcare system (3.4-6.0×). Accordingly, WW resulted in significantly higher (5.9×) patient value than PT. Although additional high-level, multicenter studies are needed to corroborate these findings, the present study may support physicians and patients in pursuing the most appropriate treatment plan for each patient based on their individualized needs and preferences.

An Updated Overview of Risk Factors for Shoulder Stiffness

A painful reduction in shoulder mobility, known as "shoulder stiffness", can occur both as a primary idiopathic condition and as a secondary condition, for example, following surgical procedures. Various factors can contribute to the development of primary shoulder stiffness. In this review we summarize the pathophysiological mechanisms, genetic influences, endocrine disorders, metabolic conditions, as well as other diseases and medical-therapeutic approaches that might have an impact on the development of primary shoulder stiffness.

Fibro-adhesive Bursitis: A Novel Sonographic Finding in Adhesive Capsulitis Patients and a Proposal of Management

INTRODUCTION

Adhesive capsulitis, also known as "frozen shoulder," is a debilitating shoulder condition increasingly linked to fibroadhesive bursitis, particularly after COVID-19 and related vaccinations. There is no definitive gold standard for its treatment, the primary therapeutic objectives of which are the reduction of pain and the restoration of shoulder range of motion. The aim of our study was to analyze treatment outcomes based on quantitative measures of shoulder function and symptom relief.

METHOD

Conducted between January 2022 and April 2023, the research involved 45 patients initially diagnosed with adhesive capsulitis and associated fibroadhesive bursitis. After excluding nine patients for other concomitant pathologies (five for calcific tendinopathy and four for rotator cuff injury), 36 patients were randomized into two groups: one group was treated with glenohumeral hydrodistension, the other with glenohumeral hydrodistension combined with bursal injection. Assessments were conducted at baseline and then 2, 4, and 6 months after treatment, focusing on changes in pain levels, functional scores, and range of motion in all planes. Each group followed a home-based rehabilitation protocol.

RESULTS

Significant improvements were observed in both treatment groups, with the combined hydrodistension and bursal injection group showing notably superior outcomes. Specifically, the range of motion in flexion improved from an initial median of 80° to 155° in the combined treatment group, compared to an increase from 75.5° to 129° in the group treated with hydrodistension alone. This enhancement was statistically significant (p < 0.001). Regarding pain reduction, the combined treatment group demonstrated a dramatic decrease in visual analogue scale (VAS) scores, from a baseline median of 7 to 1 at the 6-month follow-up. In contrast, the hydrodistension-only group showed a reduction from 7 to 3, with these differences also proving statistically significant (p < 0.001).

CONCLUSIONS

Ultrasound-guided hydrodistension of the glenohumeral joint, if combined with bursal injection and specific exercises, effectively reduces pain, decreases disability, and improves range of motion in patients with second-stage adhesive capsulitis. This study highlights the importance of a combined approach in the management of this complex condition, especially after the histological changes that occurred after COVID-19 and related vaccinations.

TRIAL REGISTRATION

ClinicalTrials.gov identifier NCT06062654.

The S2e Guideline on Shoulder Stiffness

The clinical picture of "frozen shoulder" is still poorly understood. In order to present the current state of knowledge on aetiology, diagnosis, and treatment, and to provide recommendations for the professional groups involved, a working group was formed by the DGOU and the DVSE to create a German language, evidence-based guideline, which was published in 2022 by the AWMF. The following summarises the development and the most important results.

Differences in biomechanical and metabolic factors between patients with frozen shoulder and asymptomatic individuals. A cross-sectional study

BACKGROUND

the pathogenesis of frozen shoulder (FS) is thought to be one of inflammation and fibrosis possibly influenced by hyperglycemia. Biomechanical changes of the shoulder joint in terms of muscle strength, scapular kinematics and proprioception might occur in FS.

OBJECTIVES

to compare muscle strength, scapular kinematics, proprioception, and blood glucose levels within patients with FS and to asymptomatic individuals.

DESIGN

cross-sectional study.

METHOD

Thirty-five patients with FS and 35 asymptomatic age and gender-matched individuals underwent physical assessment to determine muscle strength (abduction, external and internal rotation), scapular kinematics (both visually and with a plurimeter), proprioception (joint position sense), and blood glucose level.

RESULTS

Patients with FS showed a decrease in muscle strength in their affected shoulder compared to both the unaffected shoulder and asymptomatic individuals. Significant differences were found between the affected and unaffected shoulder in the FS group and between groups (FS versus controls) in scapular upward rotation (plurimeter) at 30° and 60° abduction. No difference in scapular kinematics (visual observation), proprioception, and blood glucose levels was found neither between shoulders in the FS group nor between groups.

CONCLUSION

A clinically relevant difference in muscle strength and increase in scapular upward rotation were found in the affected shoulder of patients with FS compared to their unaffected side and controls. However, no evidence of different levels of scapular kinematics (visual observation), proprioception, and blood glucose levels in the affected shoulder compared to the unaffected shoulder or controls is lacking.

Patient-reported allergies are associated with increased rate of postoperative stiffness after arthroscopic rotator cuff repair

BACKGROUND

Several risk factors have been identified for the development of postoperative shoulder stiffness, and there has been increasing interest in orthopedic literature regarding patient-reported allergy (PRA) as an identifiable risk factor for adverse outcomes. The purpose of this study is to determine whether PRAs are associated with subsequent rates of diagnosis of adhesive capsulitis (AC) or return to the operating room for postoperative shoulder stiffness within 2 years after arthroscopic rotator cuff repair (ARCR).

METHODS

Current Procedural Terminology surgical billing codes were used to retrospectively identify patients who underwent ARCR at a single urban academic institution from January 2012 to December 2020 with minimum 2-year follow-up. Lysis of adhesions (LOA), manipulation under anesthesia (MUA), and AC of the shoulder were further queried within 2 years postoperatively for the ipsilateral shoulder. Patients were excluded if they had undergone ipsilateral MUA/LOA or received a diagnosis of AC before the index procedure. Demographic characteristics and medical comorbidities (hypertension, diabetes, hyperlipidemia, and hypothyroidism) were extracted from electronic medical records. Baseline characteristics were compared between patients with and without PRAs. Multivariate logistic regression analyses were performed to determine the association of the presence of PRAs overall, as well as the presence of 1, 2, or 3 or more PRAs, with subsequent MUA/LOA or diagnosis of AC within 2 years postoperatively.

RESULTS

Of 7057 patients identified in the study period, 6583 were eligible for the final analysis. The mean age was 56.6 ± 11.7 years, and the mean body mass index was 29.1 ± 5.6. Overall, 19.3% of patients (n = 1271) reported at least 1 allergy, and 7.1% (n = 469) had >1 PRA. A total of 44 patients (0.7%) underwent subsequent ipsilateral MUA/LOA within 2 years postoperatively, whereas 93 patients (1.4%) received a diagnosis of ipsilateral AC in the same time frame. PRAs were significantly associated with subsequent diagnosis of AC (odds ratio [OR]: 2.39; 95% confidence interval [CI]: 1.45-3.92; P < .001), but not MUA/LOA (OR: 1.97, 95% CI: 1.26-3.61; P = .133). Patients with 2 PRAs had greater odds of being diagnosed with AC than patients with 1 PRA (OR: 2.74; 95% CI: 1.14-5.99; P = .012). Although this association was nonsignificant for MUA/LOA, patients with 2 PRAs (OR: 2.67; 95% CI: 0.96-8.80; P = .059) demonstrated a similar statistical trend.

CONCLUSION

PRAs are associated with increased odds of receiving a diagnosis of AC within 2 years after ARCR but were not found to be associated with return to the operating room for postoperative stiffness.

A new perspective of frozen shoulder pathology; the interplay between the brain and the immune system

Frozen shoulder (FS), also known as adhesive capsulitis of the shoulder (FS), is a fibrotic inflammatory process of unknown etiology whose main symptoms are pain, stiffness and the loss of joint mobility. These symptoms may be associated with pathologies such as diabetes, Dupuytren's syndrome and the prevalence of today's sedentary lifestyle. This literature review provides an overview of the epidemiology and pathogenesis of this pathology, as well as the mechanisms of lowgrade chronic inflammation and infection, insulin resistance, and omics-science associated with it. We also propose a new hypothesis related to the possibility that the GABAergic system could play a decisive role in the development of frozen shoulder and that therefore diabetes type 1, endocrinological autoimmune disorders and frozen shoulder are connected by the same pathophysiological mechanisms. If that is true, the combined presence of psycho-emotional stress factors and pathogenic immune challenges could be the main causes of frozen shoulder syndrome. Finally, we propose a series of possible intervention strategies based on a multifactorial etiological and mechanistic concept.

[Adhesive capsulitis]

BACKGROUND

Adhesive capsulitis (CA; also called Frozen shoulder) is a common, usually unilateral disease of the shoulder joint primarily affecting middle-aged women. Primary, idiopathic, and secondary forms are distinguished. Painful active and passive movement restriction are the clinically leading symptoms.

COURSE OF THE DISEASE

The disease usually progresses in three successive stages: freezing phase, frozen phase, and thawing phase.

CLINICAL DIAGNOSIS AND IMAGING

CA is primarily diagnosed clinically, with imaging being used to assess or exclude differential diagnoses. Radiography as part of basic diagnostics allows exclusion of common differential diagnoses such as osteoarthritis of the shoulder or calcific tendinitis. Native magnetic resonance imaging (MRI) and MR arthrography (MRA) reveal pathomorphologies typical of CA. Intravenously administered gadolinium increases the sensitivity of MRI. Sonography may be used as a complementary diagnostic modality or as an alternative in case of contraindications to MRI. Fluoroscopy-guided arthrography has been replaced by MRI because of its invasiveness. Computed tomography (CT) has no role in diagnostics due to its radiation exposure and significantly lower sensitivity and specificity compared to MRI.

TREATMENT

Therapy of CA is stage-adapted and includes conservative measures such as analgesics and physiotherapy and surgical procedures such as arthroscopic arthrolysis. The therapeutic spectrum is supplemented by new, innovative procedures such as transarterial periarticular embolization.

PROGNOSIS

CA is self-limiting and usually persists for 2-3 years. However, the patients may even suffer from pain and limited range of motion beyond this time.

Genetic Influence on Osteoarthritis Versus Other Rheumatic Diseases

OBJECTIVE

We aimed to compare the genetic contribution to osteoarthritis (OA) versus other rheumatic/musculoskeletal diseases (RMDs) in the same population and to explore the role for any shared genetics between OA and other RMDs.

METHODS

In 59,970 Swedish twins aged 35 years or older, we estimated the heritability (the variance explained by genetic factors) of OA in peripheral joints, back and neck pain, shoulder pain (adhesive capsulitis, impingement syndrome, etc), rheumatoid arthritis, spondyloarthritis (SpA) and psoriatic arthritis, myalgia, and osteoporosis diagnosed in specialist and inpatient care. We also studied how much covariance between OA and each of the RMDs could be explained by genetics by studying phenotypic correlations in bivariate classical twin models.

RESULTS

Any-site OA and hip OA (50% and 64%) were among the most heritable RMDs (as compared with 23% for fibromyalgia [lowest] and 63% for SpA [highest]). The highest phenotypic correlations were between OA (any joint site) and shoulder pain in the same individual (r = 0.33, 95% confidence interval 0.31-0.35), of which 70% (95% confidence interval 52-88) could be explained by shared genetics. The phenotypic correlation between OA and back/neck pain was r = 0.25, with 25% to 75% explained by genetics. Phenotypic correlations between OA and each of the other RMDs were lower (r ~ 0.1 to r ~ 0.2), with inconclusive sources of variation.

CONCLUSION

OA has relatively large heritability as compared with other RMDs. The coexistence of OA and shoulder pain, as well as back pain, was common and could often be explained by genetic factors. Findings imply similar etiologies of OA and several pain conditions.

Adhesive Capsulitis of the Shoulder: Current Concepts on the Diagnostic Work-Up and Evidence-Based Protocol for Radiological Evaluation

Adhesive capsulitis is an idiopathic and disabling disorder characterized by intense shoulder pain and progressive limitation of active and passive glenohumeral joint range of motion. Although adhesive capsulitis has been traditionally considered a diagnosis of exclusion that can be established based on a suggestive medical history and the detection of supporting findings at the physical exam, imaging studies are commonly requested to confirm the diagnostic suspicion and to exclude other causes of shoulder pain. Indeed, clinical findings may be rather unspecific, and may overlap with diseases like calcific tendinitis, rotator cuff pathology, acromioclavicular or glenohumeral arthropathy, autoimmune disorders, and subacromial/subdeltoid bursitis. Magnetic resonance imaging, magnetic resonance arthrography, and high-resolution ultrasound have shown high sensitivity and accuracy in diagnosing adhesive capsulitis through the demonstration of specific pathological findings, including thickening of the joint capsule and of the coracohumeral ligament, fibrosis of the subcoracoid fat triangle, and extravasation of gadolinium outside the joint recesses. This narrative review provides an updated analysis of the current concepts on the role of imaging modalities in patients with adhesive capsulitis, with the final aim of proposing an evidence-based imaging protocol for the radiological evaluation of this condition.

Angiotensin Receptor Blockers and Angiotensin-Converting Enzyme Inhibitors Have No Significant Relationship With Postoperative Arthrofibrosis After Shoulder Arthroscopy

Purpose

To determine the effect of perioperative angiotensin II receptor blocker (ARB) or angiotensin-converting enzyme inhibitors (ACEi) on postoperative arthrofibrosis, as defined by requiring manipulation under anesthesia (MUA) or new diagnosis of adhesive capsulitis (AC) following arthroscopic shoulder procedures.

Methods

Patients were retrospectively identified using Current Procedural Terminology surgical billing codes to identify patients who underwent any shoulder arthroscopic procedure at a single urban academic institution from 2012 to 2020 with a minimum 2-year follow-up. Patients were excluded if <30 years old at time of surgery, as these patients rarely use ARB and ACEi medications, or if they had pre-existing AC. Demographics, active medication prescriptions at the time of surgery, and medical comorbidities were recorded. Multivariable logistic regression was performed to determine the effect of ARB/ACEi on subsequent MUA or AC by 90 days, 1 year, and 2 years.

Results

In total, 5,559 patients were included in the final analysis. A majority of the cohort (53.4%) underwent arthroscopic surgery between the ages of 50 to 69 years. Most patients were male (61.8%) and without obesity (67.3%). In total, 18.9% and 15.0% were taking an ARB or ACEi medication perioperatively, respectively. Within 2 years' postoperatively, 51 patients (0.9%) underwent subsequent ipsilateral MUA, and 174 patients (3.1%) developed AC. Patients taking ARBs had a 17.5% rate of postoperative arthrofibrosis within 2-years compared with 19.1% in those not on ARBs, although this difference was not significant (P = .58). Likewise, no significant difference was found between those taking ACEi versus not (15.0% vs 15.0%, P = .99). Individual generic ARB/ACEi subgroup analysis did not demonstrate any significant associations with rate of postoperative arthrofibrosis (P > .05).

Conclusions

ARBs or ACEi did not significantly affect the rate of postoperative arthrofibrosis following shoulder arthroscopy, however female sex, diabetes mellitus, and Black/African American race were associated with an increased rate of necessitating MUA or developing AC within 2 years postoperatively.

Level of Evidence

Level III, retrospective cohort study.

Prevalence of and Risk Factors for Adhesive Capsulitis of the Shoulder in Older Adults from Germany

This study aimed to investigate the prevalence of and risk factors for adhesive capsulitis in older adults from Germany. The one-year and lifetime prevalence of adhesive capsulitis were assessed in adults aged ≥65 years with at least one visit to one of 1207 general practices in Germany in 2021. Associations between physical and psychiatric conditions and adhesive capsulitis were further assessed in older patients diagnosed for the first time with adhesive capsulitis in general practices in 2010-2021 (index date) and matched (1:5) to patients without adhesive capsulitis using a propensity score based on age, sex, and the index year. In adults without adhesive capsulitis, the index date was a randomly selected visit date in 2010-2021. The one-year and lifetime prevalence of adhesive capsulitis in older adults in 2021 were 0.4% and 2.4%, respectively. In 8439 patients with and 42,195 patients without adhesive capsulitis, 12 conditions were positively and significantly associated with adhesive capsulitis. Effect sizes were strongest for other and unspecified osteoarthritis (OR = 1.93), injury to the shoulder and upper arm (OR = 1.85), and injury to the thorax (OR = 1.47). Based on these findings, adhesive capsulitis can occur at older age, and osteoarthritis and injuries are major risk factors.

A shared genetic architecture between adhesive capsulitis and Dupuytren disease

BACKGROUND

The etiology of adhesive capsulitis involves inflammation, thickening, and fibrosis of the shoulder capsule. The underlying genetic factors are poorly understood. The purpose of this study was to identify genetic variants associated with adhesive capsulitis using the UK Biobank (UKB) cohort and compare them with variants associated with Dupuytren disease investigating a common etiology between the 2 fibrotic disorders.

METHODS

A genome-wide association study (GWAS) was performed using data from UKB with 10,773 cases of adhesive capsulitis, and a second GWAS was performed with 8891 cases of Dupuytren disease. Next, a comparison of association statistics was performed between adhesive capsulitis and Dupuytren disease using the data from both GWAS. Finally, single-nucleotide polymorphisms (SNPs) previously reported from candidate gene studies for adhesive capsulitis and Dupuytren disease were tested for association with adhesive capsulitis and Dupuytren disease using the summary statistics from their respective GWAS.

RESULTS

The UKB GWAS for adhesive capsulitis identified 6 loci that reached genome-wide statistical significance: a cluster of 11 closely linked SNPs on chromosome 1; a single SNP on chromosome 2; a single SNP on chromosome 14; 2 closely linked SNPs on chromosome 21; 33 closely linked SNPs on chromosome 22; and 3 closely linked SNPs on the X chromosome. These SNPs were associated with 8 different genes including TSPAN2/NGF, SATB2, MRPL52/MMP14, ERG, WNT7B, and FGF13. A GWAS for Dupuytren disease was performed and a comparison to the adhesive capsulitis GWAS showed 13 loci significantly associated with both phenotypes. A validation attempt of 6 previously reported SNPs associated with adhesive capsulitis using UKB summary statistics was unable to confirm any of the previously reported SNPs (all P > .19). All 23 previously reported SNPs associated with Dupuytren disease were confirmed using the UKB summary statistics (P < 2.1 × 10^-3) CONCLUSION: This GWAS investigating adhesive capsulitis has identified 6 novel loci involving 8 different genes to be associated with adhesive capsulitis. A GWAS investigating Dupuytren disease was performed and compared to the adhesive capsulitis GWAS, and 13 common loci were identified between the 2 disorders with genes involved in pathologic fibrosis. We were unable to validate the SNPs in candidate genes previously reported to be associated with adhesive capsulitis although we were able to confirm all previously reported SNPs associated with Dupuytren disease. The strong genetic overlap between the adhesive capsulitis and Dupuytren disease loci suggests a similar etiology between the 2 diseases.

Understanding the clinical profile of patients with frozen shoulder: a longitudinal multicentre observational study

INTRODUCTION

There is a large diversity in the clinical presentation of frozen shoulder (FS) and the clinical outcome is not always satisfactory. The aim of the current study was to examine to what extent range of motion (ROM) limitation, metabolic factors (diabetes mellitus and thyroid disorders), autonomic symptoms and pain sensitivity may contribute to the prognosis in terms of shoulder pain and disability and quality of life in patients with FS.

METHODS

Patients with stage 1 or 2 FS were longitudinally followed-up during 9 months after baseline assessment. They completed six questionnaires and underwent quantitative sensory testing (pressure pain thresholds, temporal summation and conditioned pain modulation) and ROM assessment.

RESULTS

One hundred and forty-nine patients with FS were initially recruited and 121 completed at least one follow-up measurement. Shoulder pain and disability improved over time and diabetes mellitus was found to be a prognostic factor for final outcome. Several domains of quality of life also improved over time and external rotation ROM, diabetes mellitus, thyroid disorder and autonomic symptoms were found to be prognostic factors for final outcome. These prognostic factors explained 2.5%-6.3% of the final outcome of shoulder pain and disability and quality of life.

DISCUSSION AND CONCLUSION

In patients with FS, prognostic variables were able to predict different outcomes, indicating that outcomes in this population can be variable-dependent. Other variables not explored in this study might contribute to the prognosis of patients with FS, which should be investigated in future research. In clinical practice, baseline assessment of prognostic factors and focusing on a more holistic approach might be useful to inform healthcare practitioners about progression of patients with FS during a 9-month period.

Genome-Wide Association Study of Adhesive Capsulitis Suggests Significant Genetic Risk Factors

BACKGROUND

Adhesive capsulitis of the shoulder involves loss of passive range of motion with associated pain and can develop spontaneously, with no obvious injury or inciting event. The pathomechanism of this disorder remains to be elucidated, but known risk factors for adhesive capsulitis include diabetes, female sex, and thyroid dysfunction. Additionally, transcriptional profiling and pedigree analyses have suggested a role for genetics. Identification of elements of genetic risk for adhesive capsulitis using population-based techniques can provide the basis for guiding both the personalized treatment of patients based on their genetic profiles and the development of new treatments by identification of the pathomechanism.

METHODS

A genome-wide association study (GWAS) was conducted using the U.K. Biobank (a collection of approximately 500,000 patients with genetic data and associated ICD-10 [International Classification of Diseases, 10th Revision] codes), comparing 2,142 patients with the ICD-10 code for adhesive capsulitis (M750) to those without. Separate GWASs were conducted controlling for 2 of the known risk factors of adhesive capsulitis-hypothyroidism and diabetes. Logistic regression analysis was conducted controlling for factors including sex, thyroid dysfunction, diabetes, shoulder dislocation, smoking, and genetics.

RESULTS

Three loci of significance were identified: rs34315830 (in WNT7B; odds ratio [OR] = 1.28; 95% confidence interval [CI], 1.22 to 1.39), rs2965196 (in MAU2; OR = 1.67; 95% CI, 1.39 to 2.00), and rs1912256 (in POU1F1; OR = 1.22; 95% CI, 1.14 to 1.31). These loci retained significance when controlling for thyroid dysfunction and diabetes. The OR for total genetic risk was 5.81 (95% CI, 4.08 to 8.31), compared with 1.70 (95% CI, 1.18 to 2.36) for hypothyroidism and 4.23 (95% CI, 2.32 to 7.05) for diabetes.

CONCLUSIONS

The total genetic risk associated with adhesive capsulitis was significant and similar to the risks associated with hypothyroidism and diabetes. Identification of WNT7B, POU1F1, and MAU2 implicates the Wnt pathway and cell proliferation response in the pathomechanism of adhesive capsulitis.

LEVEL OF EVIDENCE

Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Autonomic Nervous System Function and Central Pain Processing in People With Frozen Shoulder: A Case-control Study

OBJECTIVES

The pathophysiology of a frozen shoulder (FS) is thought to be related to chronic inflammation. Chronic inflammation may disturb the immune system and consequently the nervous system as part of an overarching system. The aim of this study was to determine the presence of disturbed autonomic nervous system function and altered central pain processing (CPP) in patients with FS. Secondarily, the presence of psychological variables (catastrophizing and hypervigilance) and self-reported associated symptoms of altered CPP in patients with FS were investigated.

METHODS

Patients with FS and healthy controls completed the Composite Autonomic Symptom Score (autonomic function) and underwent quantitative sensory testing to assess tactile sensitivity (ie, allodynia), pressure pain thresholds (PPTs, ie, hyperalgesia), temporal summation of pain, and Conditioned Pain Modulation (CPM). Psychological issues were explored with the Pain Catastrophizing Scale and the Pain Vigilance and Awareness Questionnaire, and self-reported symptoms associated with altered CPP were determined with the Central Sensitization Inventory.

RESULTS

Thirty-two patients with FS and 35 healthy controls were analyzed in the study. Patients with FS showed more self-reported autonomic symptoms and symptoms of altered CPP, higher levels of pain catastrophizing and hypervigilance, and are more sensitive to tactile touches and mechanical pressure compared with controls.

DISCUSSION

On the basis of the effect sizes, between-group differences in allodynia, hyperalgesia, catastrophizing, and hypervigilance were clinically relevant, but only local allodynia, hyperalgesia, catastrophizing, and hypervigilance were statistically different. Therefore, obvious altered CPP was not present at the group level in patients with FS compared with controls.

An Instrument-Assisted Coracoid Pain Test: An Exploratory Diagnostic Accuracy Study

The coracoid pain test (CPT) could contribute to the diagnosis of frozen shoulder (FS) with palpation. However, due to assessor performance these values might be unreliable. Therefore, the aim was to explore the diagnostic accuracy of an instrument-assisted CPT and two alternative approaches (pain severity and side comparison) for assistance in the diagnosis of FS. Patients with FS and healthy age-matched controls were recruited. All participants underwent the instrument-assisted CPT on both shoulders with a pressure algometer. Sensitivity, specificity, and likelihood ratios were determined for the three approaches. In total, 35 patients with FS and 35 healthy participants were included. The original approach was positive in eight participants (11.4%), with only sufficient specificity to draw a conclusion. The pain severity approach was positive in 31 participants (44.3%) with sufficient sensitivity, specificity and likelihood ratios. The side comparison approach was positive in 10 participants (14.3%) with excellent specificity and positive likelihood ratio. The specificity of the instrument-assisted CPT can be used to increase the probability of FS with both the original and alternative approaches. Only the pain severity approach can draw a conclusion with a negative test result. This study should be repeated with a cross-sectional design to strengthen and confirm the conclusions.

The Impact of Suprascapular Nerve Interventions in Patients with Frozen Shoulder: A Systematic Review and Meta-Analysis

BACKGROUND

Frozen shoulder is a common condition resulting in severe pain and restricted range of motion. An assessment of the effectiveness of interventions may provide an improved understanding of the development and management of frozen shoulder.

METHODS

A literature search was conducted using Embase, the Cumulative Index of Nursing and Allied Health (CINAHL), the Cochrane Central Register of Controlled Trials (CENTRAL), and National Center for Biotechnology Information PubMed using relevant terms. Studies were included if they assessed the outcomes of interventions on the suprascapular nerve that aim to improve the symptoms of frozen shoulder.

RESULTS

A database search returned 196 articles. After review, 9 articles met the inclusion criteria and were included in the analysis. Suprascapular nerve interventions (nerve block, pulsed radiofrequency lesioning) are associated with improvement in pain, motion, and function. Meta-analysis showed that pain (Hedges g, -3.084 [95% confidence interval (CI), -4.273 to -1.894]; p < 0.001) and range of motion (Hedges g, 2.204 [95% CI, 0.992 to 3.415]; p < 0.001) improved significantly following suprascapular nerve block (SSNB).

CONCLUSIONS

SSNB is associated with significant improvements in shoulder pain and range of motion in patients with frozen shoulder. Further randomized controlled trials comparing SSNB with intra-articular injection and other nonoperative treatments are required to fully define its role in the management of frozen shoulder.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

The epidemiology and etiology of adhesive capsulitis in the U.S. Medicare population

Background

Adhesive capsulitis (AC) of the shoulder, also known as frozen shoulder, causes substantial pain and disability. In cases of secondary AC, the inflammation and fibrosis of the synovial joint can be triggered by trauma or surgery to the joint followed by extended immobility. However, for primary AC the inciting trigger is unknown. The burden of the disorder among the elderly is also unknown leading to this age group being left out of therapeutic research studies, potentially receiving delayed diagnoses, and unknown financial costs to the Medicare system. The purpose of this analysis was to describe the epidemiology of AC in individuals over the age of 65, an age group little studied for this disorder. The second purpose was to investigate whether specific medications, co-morbidities, infections, and traumas are risk factors or triggers for primary AC in this population.

Methods

We used Medicare claims data from 2010–2012 to investigate the prevalence of AC and assess comorbid risk factors and seasonality. Selected medications, distal trauma, and classes of infections as potential inflammatory triggers for primary AC were investigated using a case–control study design with patients with rotator cuff tears as the comparison group. Medications were identified from National Drug codes and translated to World Health Organization ATC codes for analysis. Health conditions were identified using ICD9-CM codes.

Results

We found a one-year prevalence rate of AC of approximately 0.35% among adults aged 65 years and older which translates to approximately 142,000 older adults in the United States having frozen shoulder syndrome. Diabetes and Parkinson’s disease were significantly associated with the diagnosis of AC in the elderly. Cases were somewhat more common from August through December, although a clear seasonal trend was not observed. Medications, traumas, and infections were similar for cases and controls.

Conclusions

This investigation identified the burden of AC in the US elderly population and applied case–control methodology to identify triggers for its onset in this population. Efforts to reduce chronic health conditions such as diabetes may reduce seemingly unrelated conditions such as AC. The inciting trigger for this idiopathic condition remains elusive.

An overview of effective and potential new conservative interventions in patients with frozen shoulder

Frozen shoulder (FS) is a pathology that is difficult to understand and difficult to manage. Over the last ten years, contradictory and new evidence is provided regarding the recovery and its natural course. This narrative review provides new information about the diagnosis and conservative treatment of patients with FS and ongoing research hypotheses that might provide new insights in the pathology and treatment options. FS has a characteristic course. People with Diabetes Mellitus and thyroid disorders have a higher risk of developing a FS. The diagnosis FS is based on pattern recognition and physical examination. Additionally, 'rule-in' and 'rule-out' criteria can be used to increase the likelihood of the frozen shoulder diagnosis. Recommended and most common physical therapy interventions are mobilization techniques and exercises, in which tissue irritability can guide its intensity. In addition, physical therapy is often complementary with patient education and pharmacotherapy. The latest evidence-based practice related to FS is proprioceptive neuromuscular facilitation and mirror therapy. In addition, interventions like pain neuroscience education, high-intensity interval training and lifestyle changes are still hypothetical. Finally, better insight in the involvement of biochemical processes, function of myofibroblasts and matrix metalloproteinases can provide better understanding in the pathophysiology and will be addressed in current review.

Exercise Therapy is Effective for Improvement in Range of Motion, Function, and Pain in Patients With Frozen Shoulder: A Systematic Review and Meta-analysis

OBJECTIVE(S)

To determine (1) the effect of exercise therapy alone or in combination with other interventions compared with solely exercises and programs with or without exercises and (2) what kind of exercise therapy or combination with other interventions is most effective.

DATA SOURCES

PubMed, Web of Science and Cochrane Central Register of Controlled Trials.

STUDY SELECTION

Studies were screened in a 2-phase approach by 2 independent reviewers (M.M. and L.M.). Reference lists of included studies and interesting systematic reviews were hand searched.

DATA EXTRACTION

Two independent reviewers (M.M. and L.M.) extracted information about origin, characteristics of study participants, eligibility criteria, characteristics of interventions, outcome measures and main results in a pre-defined template.

DATA SYNTHESIS

Thirty-three studies were included in the qualitative and 19 in the meta-analysis. Preliminary evidence was found for supervised exercises to be more beneficial than home exercises for ROM and function. Multimodal programs comprising exercises may result in little to no difference in ROM compared to solely exercises. Programs comprising muscle energy techniques show little to no difference in ROM when compared with programs with other exercises. Adding stretches to a multimodal program with exercises may increase ROM. There is uncertain evidence that there is a difference between those programs regarding function and pain. Preliminary evidence was found for several treatment programs including exercises to be beneficial for improvement in both passive and active ROM, function, pain, and muscle strength. No studies used patient satisfaction as an outcome measure.

CONCLUSIONS

ROM, function, and pain improve with both solely exercises and programs with exercises, but for ROM and pain there was little to no difference between programs and for function the evidence was uncertain. Adding exercises improve active ROM compared with a program without exercises, whereas adding physical modalities has no beneficial effect. Muscle energy techniques are a beneficial type of exercise therapy for improving function compared with other types of exercise. Unfortunately, no conclusion can be drawn about the results in the long-term and most effective dose of exercise therapy.

Effectiveness of arthroscopic management of idiopathic shoulder stiffness: A meta-analysis

BACKGROUND

Persisting shoulder stiffness adversely affects quality of life by causing pain and motion restrictions especially in patients with diabetes.

OBJECTIVE

The aim of this study was to evaluate the outcomes of arthroscopic capsular release in patients with idiopathic shoulder stiffness.

METHOD

A literature search was conducted in electronic databases and studies were selected by following precise eligibility criteria. Random-effects meta-analyses were performed to estimate the changes at latest follow-up in scores of the Constant, American Shoulder and Elbow Surgeons (ASES), and University of California at Los Angelis (UCLA) scales, Visual Analogue Scale (VAS), and shoulder range of motion.

RESULTS

Nineteen studies were included. The follow-up duration was 42 months [95% confidence interval (CI): 32, 51]. Improvements in scores of the Constant, ASES, UCLA scales, and VAS were 48.3 [95% CI: 38.0, 58.6], 44.6 [95% CI: 24.6, 64.6], 19.3 [95% CI: 16.6, 22.0], and -6.1 [95% CI: -6.9, -5.4] respectively (P< 0.05 all). Improvements in the shoulder range of motion were: abduction 82.0 [95% CI: 65.0, 98.9]; forward flexion 75.9 [95% CI: 59.7, 92.1]; external rotation 43.2 [95% CI: 37.5, 49.0]; and internal rotation 25.4 [95% CI: 15.2, 35.5] degrees; P< 0.05 all).

CONCLUSION

Arthroscopic capsular release effectively improves shoulder function in patients with idiopathic shoulder stiffness.

Frozen Shoulder: A Systematic Review of Cellular, Molecular, and Metabolic Findings

BACKGROUND

Frozen shoulder is a common, poorly understood condition affecting the shoulder joint, with poor long-term outcomes in some in relation to pain and mobility. Understanding the pathophysiology of frozen shoulder at a cellular level and a molecular level may help in the development of novel treatments. The aim of this study was to perform a systematic review of studies examining the cellular, molecular, and metabolic findings in frozen shoulder.

METHODS

A literature search was conducted using Embase, CINAHL (Cumulative Index of Nursing and Allied Health Literature), and PubMed using relevant terms. Studies were included if they assessed cellular, molecular, or metabolic alterations in tissue or blood samples of patients with frozen shoulder.

RESULTS

Of 4,794 studies identified, 25 were included for analysis. Histological findings included nonspecific chronic inflammation and the proliferation of fibroblasts, adipocytes, and blood vessels. Molecular studies showed increased pro-inflammatory mediators, reduced matrix metalloproteinases (MMPs), and increased activity of factors promoting fibroblast activation and nerve growth. Metabolic alterations included an increase in blood lipids.

CONCLUSIONS

Frozen shoulder is thought to occur after a primary insult to the shoulder triggers a complex cascade and upregulation of growth factors and cytokines with an increased turnover of the extracellular matrix, activation of myofibroblasts with deposition of collagen, and reduced matrix degradation. The presence of a background pro-inflammatory state (e.g., patients with diabetes or hyperlipidemia) may exacerbate these abnormalities. Further work assessing patients in early stages of the disease and comparing the inflammatory or fibrogenic characteristics of the shoulder capsule with those of the other joints may help to determine the initiating factors and to explain the predisposition of the shoulder to stiffness.

CLINICAL RELEVANCE

Our findings may form the basis for identifying new targets for the clinical management of frozen shoulder.

Human Fibrosis: Is There Evidence for a Genetic Predisposition in Musculoskeletal Tissues?

BACKGROUND

Pathologic fibrosis is characterized by dysregulation of gene expression with excessive extracellular matrix production. The genetic basis for solid organ fibrosis is well described in the literature. However, there is a paucity of evidence for similar processes in the musculoskeletal (MSK) system. The purpose of this review is to provide an overview of existing evidence of genetic predisposition to pathologic fibrosis in the cardiac, pulmonary, and MSK systems, and to describe common genetic variants associated with these processes.

METHODS

A comprehensive search of several databases from 2000 to 2019 was conducted using relevant keywords in the English language. Genes reported as involved in idiopathic fibrotic processes in the heart, lung, hand, shoulder, and knee were recorded by 2 independent authors.

RESULTS

Among 2373 eligible studies, 52 studies investigated genetic predisposition in terms of variant analysis with the following organ system distribution: 36 pulmonary studies (69%), 15 hand studies (29%), and 1 knee study (2%). Twenty-two percent of gene variants identified were associated with both pulmonary and MSK fibrosis (ie, ADAM, HLA, CARD, EIF, TGF, WNT, and ZNF genes). Genetic variants known to be involved in the MSK tissue development or contractility properties in muscle were identified in the pulmonary fibrosis.

CONCLUSION

Despite shared genetic variations in both the lung and hand, there remains limited information about genetic variants associated with fibrosis in other MSK regions. This finding establishes the necessity of further studies to elucidate the genetic determinants involved in the knee, shoulder, and other joint fibrotic pathways.

LEVEL OF EVIDENCE

Level III.

The Effectiveness of Acupuncture in the Treatment of Frozen Shoulder: A Systematic Review and Meta-Analysis

Background

Frozen shoulder (FS) is associated with pain, reduced range of motion (ROM), and shoulder function. The condition occurs in 2-5% of the population, and it is especially common around the age of 50 years. FS symptoms will recover after 1-4 years. Many patients turn to acupuncture in order to alleviate the FS symptoms.

Objective

In this review, we will investigate the efficiency of acupuncture as a FS treatment.

Methods

A literature search of acupuncture and FS-related keywords was performed in the following databases: PubMed, Cochrane Library, Embase, and Web of Science. Thirteen publications were included for a systematic review, and a meta-analysis was done using the following measurements: visual analogue scale (VAS) for pain, Constant-Murley Shoulder Outcome Score (CMS) for shoulder function, and active shoulder ROM including flexion, abduction, and external rotation. The Cochrane Collaboration's risk of bias tool and quality of evidence GRADE recommendations and STRICTA 2010 were used to grade the included publications.

Results

A meta-analysis on VAS pain score showed significant pain reduction, restoring CMS shoulder function, and flexion ROM in favor of acupuncture versus the control. In external rotation and abduction ROM, a meta-analysis was not significant. The most used acupoints are Jian Yu (LI15) and Jian Liao (TB14).

Conclusions

The results indicate that acupuncture could be safe and effective for pain reduction, restoring shoulder function, and restoring flexion ROM for FS patients in the short term and midterm. However, the level of evidence was very low. More high-quality and longer studies are needed in order to robust the evidence.

'Frozen shoulder' is ill-defined. How can it be described better?

Frozen shoulder, a common and debilitating shoulder complaint, has been the subject of uncertainty within the scientific literature and clinical practice.

We performed an electronic PubMed search on all (1559) articles mentioning ‘frozen shoulder’ or ‘adhesive capsulitis’ to understand and qualify the range of naming, classification and natural history of the disease. We identified and reviewed six key thought leadership papers published in the past 10 years and all (24) systematic reviews published on frozen shoulder or adhesive capsulitis in the past five years.

This revealed that, while key thought leaders such as the ISAKOS Upper Extremity Council are unequivocal that ‘adhesive capsulitis’ is an inappropriate term, the long-term and short-term trends showed the literature (63% of systematic reviews assessed) preferred ‘adhesive capsulitis’.

The literature was divided as to whether or not to classify the complaint as primary only (9 of 24) or primary and secondary (9 of 24); six did not touch on classification.

Furthermore, despite a systematic review in 2016 showing no evidence to support a three-phase self-limiting progression of frozen shoulder, 11 of 12 (92%) systematic reviews that mentioned phasing described a three-phase progression. Eight (33%) described it as ‘self-limiting’, three (13%) described it as self-limiting in ‘nearly all’ or ‘most’ cases, and six (25%) stated that it was not self-limiting; seven (29%) did not touch on disease resolution.

We call for a data and patient-oriented approach to the classification and description of the natural history of the disease, and recommend authors and clinicians (1) use the term ‘frozen shoulder’ over ‘adhesive capsulitis’, (2) use an updated definition of the disease which recognizes the often severe pain suffered, and (3) avoid the confusing and potentially harmful repetition of the natural history of the disease as a three-phase, self-limiting condition.

Cite this article: EFORT Open Rev 2020;5:273-279.DOI: 10.1302/2058-5241.5.190032

Patients with Axial Spondyloarthritis Are at Risk of Developing Adhesive Capsulitis: Real-World Evidence Database Study in Taiwan

Patients with axial spondyloarthritis (ax-SpA) present with inflammation invading the axial skeleton. Symptoms of ax-SpA interfere with patients' quality of life, and peripheral symptoms are also noted. Human leukocyte antigen B27 was associated with adhesive capsulitis. However, epidemiological studies investigating the associated incidence and risk factors for patients with ax-SpA with adhesive capsulitis are limited. The data of patients with ax-SpA were recorded during the 2004-2008 period and followed to the end of 2010. The control cohort comprised age- and sex-matched non-ax-SpA subjects. A Cox multivariate proportional hazards model was applied to analyze the risk factors for adhesive capsulitis. The hazard ratio (HR) and adjusted hazard ratio (aHR) were estimated between the study and control cohorts after confounders were adjusted for. Effects of sulfasalazine (SSZ), methotrexate (MTX), and hydroxychloroquine (HCQ) use on adhesive capsulitis risk were also analyzed. We enrolled 2859 patients with ax-SpA in the study cohort and 11,436 control subjects. A higher incidence of adhesive capsulitis was revealed in the ax-SpA cohort: The crude HR was 1.63 (95% CI, 1.24-2.13; p < 0.001), and the aHR was 1.54 (95% CI, 1.16-2.05; p = 0.002). For patients with ax-SpA using SSZ or HCQ, no difference in aHR was noted compared with control participants, but patients with ax-SpA treated with MTX had higher HR and aHR than controls. Patients with ax-SpA are at risk for adhesive capsulitis. When these patients receive SSZ or HCQ, the risk of adhesive capsulitis can be lowered compared with that of the control cohort.

[Primary (idiopathic) shoulder stiffness : Definition, disease progression, epidemiology and etiology]

Shoulder stiffness is characterized by restriction of the active and passive movement of the glenohumeral joint. The stiffness is ultimately caused by fibrosis and the resulting contracture of the glenohumeral joint capsule and its ligaments; however, the term stiff shoulder is only a descriptive umbrella term that must be further defined as the course of the disease and the recommended treatment are decisively influenced by the cause of the shoulder stiffness. Primary shoulder stiffness, also known as idiopathic shoulder stiffness or "frozen shoulder", must be distinguished from various forms of secondary shoulder stiffness and often occurs in three stages, which can all last for several months to years: the initial "freezing phase", followed by a "frozen phase" and finally a "thawing phase". Although primary shoulder stiffness is a frequent pathological alteration with an prevalence of 2-5% in the general population, the exact etiology remains largely unknown; however, there is consensus throughout the literature that certain systemic pathologies, such as diabetes mellitus are associated with a higher incidence of primary shoulder stiffness.

Adhesive capsulitis of the shoulder: protocol for the adhesive capsulitis biomarker (AdCaB) study

Background

Adhesive capsulitis (AC) is a disabling and poorly understood pathological condition of the shoulder joint. The current study aims to increase our understanding of the pathogenesis, diagnosis and clinical outcomes of people with AC by investigating: 1) transcriptome-wide alterations in gene expression of the glenohumeral joint capsule in people with AC compared to people with non-inflammatory shoulder instability (controls); 2) serum and urine biomarkers to better understand diagnosis and staging of AC; and 3) clinical outcomes in people with AC compared to controls 12-months following arthroscopic capsular release or labral repair respectively.

Methods

The study is a prospective multi-centre longitudinal study investigating people undergoing arthroscopic capsulotomy for AC compared to people undergoing arthroscopic stabilization for shoulder instability. Tissue samples collected from the anterior glenohumeral joint capsule during surgery will undergo RNA-seq to determine differences in gene expression between the study groups. Gene Set Enrichment Analysis will be used to further understand the pathogenesis of AC as well as guide serum and urine biomarker analysis. Clinical outcomes regarding pain, function and quality of life will be assessed using the Oxford Shoulder Score, Oxford Shoulder Instability Score, Quick DASH, American Shoulder and Elbow Society Score, EQ-5D-5 L and active shoulder range of movement. Clinical outcomes will be collected pre-operatively and 12-months post-operatively and study groups will be compared for statistically significant differences using linear regression, adjusting for baseline demographic variables.

Discussion

This study will provide much needed information regarding the pathogenesis, diagnosis and staging of AC. It will evaluate clinical outcomes for people undergoing arthroscopic release of AC by comparing this group to people undergoing arthroscopic surgery for shoulder instability.

Trial registration

ACTRN12618000431224, retrospectively registered 26 March 2018.

Risk Factors for Shoulder Stiffness: Current Concepts

Shoulder stiffness is a condition of painful restriction of the glenohumeral range of motion. Numerous risk factors for primary and postoperative shoulder stiffness have been described. This article summarizes the known aspects of the pathophysiology of shoulder stiffness, with special attention to elements of molecular biology and genetics, which could influence the risk of developing shoulder stiffness. Furthermore, the role of hormonal and metabolic factors, medical disorders, drugs, and of other published risk factors for primary and postoperative shoulder stiffness is reviewed and discussed. Finally, aspects related to shoulder surgery and postoperative rehabilitation protocols, which could influence the development of postoperative stiffness are presented.

Adhesive capsulitis of the shoulder: review of pathophysiology and current clinical treatments

Adhesive shoulder capsulitis, or arthrofibrosis, describes a pathological process in which the body forms excessive scar tissue or adhesions across the glenohumeral joint, leading to pain, stiffness and dysfunction. It is a debilitating condition that can occur spontaneously (primary or idiopathic adhesive capsulitis) or following shoulder surgery or trauma (secondary adhesive capsulitis). Here, we review the pathophysiology of adhesive shoulder capsulitis, highlighting its clinical presentation, natural history, risk factors, pathoanatomy and pathogenesis. Both current non-operative and operative treatments for adhesive capsulitis are described, and evidence-based studies are presented in support for or against each corresponding treatment. Finally, the review also provides an update on the gene expression profile of adhesive capsulitis and how this new understanding can help facilitate development of novel pharmacological therapies.