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

Risk factors and predictive models for frozen shoulder

This study aims to explore the risk factors associated with frozen shoulder (FS) and develop a predictive model for diagnosing FS, in order to facilitate early detection of the condition. A total of 103 patients diagnosed with FS and admitted to the Department of Joint Surgery at Suining Central Hospital between October 2021 and October 2023 were consecutively included in the study. Additionally, 309 individuals without shoulder joint diseases, matched for age and gender, who visited the department during the same time, were included as the control group.The complete recording of clinical data for all patients was followed by the utilization of statistical tests such as the Mann-Whitney U test, sample t test, and chi-square test to compare different groups. Additionally, multivariate binary logistic regression analysis was employed to identify risk factors associated with the occurrence of FS in patients, leading to the establishment of a prediction model and derivation of a simplified equation. The diagnostic effectiveness of individual indicators and prediction models was assessed through the use of receiver operating characteristic (ROC) curve analysis. In the sample of 103 individuals, 35 were identified as male and 68 as female, with an average age range of 40-70 years (mean age: 54.20 ± 6.82 years). The analysis conducted between different groups revealed that individuals with a low body mass index (BMI), in conjunction with other factors such as diabetes, cervical spondylosis, atherosclerosis, and hyperlipidemia, were more susceptible to developing FS. Logistic regression analysis further indicated that low BMI, diabetes, cervical spondylosis, and hyperlipidemia were significant risk factors for the occurrence of FS. These variables were subsequently incorporated into a predictive model, resulting in the creation of a simplified equation.The ROC curve demonstrated that the combined indicators in the predictive model exhibited superior diagnostic efficacy compared to single indicators, as evidenced by an area under the curve of 0.787, sensitivity of 62.1%, and specificity of 82.2%. Low BMI, diabetes, cervical spondylosis, and hyperlipidemia are significant risk factors associated with the occurrence of FS. Moreover, the utilization of a prediction model has demonstrated superior capability in forecasting the likelihood of FS compared to relying solely on individual indicators. This finding holds potential in offering valuable insights for the early diagnosis of FS.

Exploring the link between metformin use and adhesive capsulitis of the shoulder: a retrospective cohort study in Taiwan

The risk of adhesive capsulitis of shoulder in diabetic patients taking metformin has not been evaluated. We aimed for evaluating the relative risk of adhesive capsulitis of shoulder in diabetic patients taking metformin at the level of the whole country population. We conducted a retrospective cohort study using a national health insurance database in Taiwan from 2000 to2015. We used International Classification of Diseases, Ninth Revision, to categorise the medical condition for study group and comparison group. We used Cox proportional hazard regression analyses to determined adjusted hazard ratios (aHRs) of adhesive capsulitis of shoulder between study and comparison group after adjusting for sex, age, and comorbidities.Among 30,412 diabetic patients using metformin, 3020 patients were diagnosis with adhesive capsulitis of shoulder during follow up. Of the 121,648 patients without the use of metformin, 11,375 patients developed adhesive capsulitis of shoulder. Adhesive capsulitis of shoulder risk was elevated in patients taking metformin than in non-metformin group (adjusted hazard ratio [HR] 1.179, 95% confidence interval [95% CI] 1.022 to 1.268; p = 0.039). Risk of adhesive capsulitis of shoulder among the diabetic patients taking metformin was higher than those did not taking metformin.

Matrix metalloproteinase-1 and matrix metalloproteinase-9 are highly expressed in the joint capsule of diabetic frozen shoulder

BACKGROUND

The pathophysiology of frozen shoulder (FS) involves abnormal expressions of matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinases (TIMPs) that lead to capsular fibrosis. However, there has been little concern for why diabetic FS has more protracted fibrotic condition. The objective of this study was to compare the expression levels of MMPs and TIMPs in the joint capsule of patients with diabetic and nondiabetic FS.

MATERIALS AND METHODS

Samples of capsular tissue were collected from 20 patients with FS (10 diabetic patients; diabetic group and 10 nondiabetic patients; nondiabetic group) and 10 patients (control group) with chronic anterior shoulder instability. Quantitative real-time reverse transcriptase-polymerase chain reaction and Western blot analysis were performed to determine the expression levels of mRNA and protein for MMP-1, 3, 9, 13, 14, and TIMP-1, 2.

RESULTS

The results of quantitative real-time reverse transcriptase-polymerase chain reaction showed significantly higher expression levels of all MMPs and TIMP-1 and significantly lower expression levels of TIMP-2 in the joint capsule of patients in the diabetic or nondiabetic groups compared with the control group. Significantly higher expression levels of MMP-1, 9, 14, and TIMP-1 were detected in the diabetic group compared with the nondiabetic group. The results of Western blot analysis showed significantly higher levels of MMP-3, 13, 14, and TIMP-1 in the joint capsule of patients in the diabetic or nondiabetic groups compared with the control group. However, no significant differences of protein levels of them were observed between diabetic and nondiabetic groups.

CONCLUSIONS

The findings of this study demonstrate the potential involvement of MMP-1 and 9 in the pathophysiology of diabetic FS. These findings may be helpful in identification of therapeutic targets for development of novel treatments for this protracted chronic fibrosing condition.

Decreased rotator cuff muscle cross-sectional areas in subjects with adhesive capsulitis: a study comparing male and female subjects

OBJECTIVE

To compare rotator cuff (RC) muscle cross-sectional areas (CSA) in subjects with adhesive capsulitis (AC) to age- and sex-matched controls.

MATERIALS AND METHODS

We retrospectively analyzed 97 shoulder MRIs or MR arthrography studies, of which 42 were clinically diagnosed with AC (27 female, 15 male) and 55 were age- and sex-matched controls (38 female, 17 male). All AC subjects underwent imaging ≥ 6 months after symptom onset. All imaging was examined to exclude RC full-thickness tears and prior surgery. A standardized T1 sagittal MR image was segmented in each subject to obtain the CSA of subscapularis (SSC), supraspinatus (SSP), and infraspinatus (ISP) muscles. Differences in CSAs between AC and control subjects were analyzed by sex (females and males separately) and all subjects combined.

RESULTS

AC females had significantly decreased SSC (P = 0.002) and total (P = 0.006) CSAs compared to controls. Male AC subjects showed decreased SSC (P = 0.044), SSP (P = 0.001), and total (P = 0.005) CSAs. Across all subjects, male and female, the AC cohort had significantly decreased SSC (P = 0.019) and total (P = 0.029) CSAs compared to controls.

CONCLUSION

Decreased RC muscle CSAs were present in AC subjects with ≥ 6 months of symptom duration, with decreased SSC and total CSAs in male and female subjects, and decreased SSP CSA in males.

Frozen shoulder. An overview of pathology and biology with hopes to novel drug therapies

Frozen shoulder (FS) is a common disorder characterized by spontaneous onset of shoulder pain accompanied by progressive loss of range-of-motions. The cause of FS is still unclear, and radical therapy has not been established. With the final aim of preventing or curing FS at an earlier stage, we reviewed the pathological and biological features of this disease. Many studies indicate that the main pathology of FS is inflammation initially and fibrosis later. There are inflammatory cytokines, immune cells, fibrotic growth factors, and type-III collagen in the synovium and the joint capsule. The immune cell landscape switches from the macrophages to T cells. Activated fibroblasts seem to regulate the inflammatory and fibrotic processes. The imbalance between matrix metalloproteinases and tissue inhibitors of metalloproteases might promote fibrosis. Additionally, advanced glycation end-products are noted in the FS synovium. Diabetes mellitus and hypothyroidism are closely related to the development of FS. In terms of nonsurgical treatment, oral or intra-articular glucocorticoids are the only drugs that provide early benefit. Some other anti-inflammatory or antifibrotic drugs may potentially control the FS, but have not been proven effective in the clinical setting. Future studies should be targeted to develop steroid-sparing agents that inhibit biological events in FS.

Dynamics of disability and pain indicators under the influence of physical therapy for adhesives capsulitis and myofascial pain syndrome

OBJECTIVE

Aim: To compare the effectiveness of end-range mobilization and therapeutic exercises, used in combination with ischemic compression, on disability and pain indicators among patients with adhesive capsulitis of the shoulder joint and thoracic myofascial pain syndrome.

PATIENTS AND METHODS

Materials and Methods: The study involved 68 patients. Goniometry of the shoulder joint, assessment of pain in myofascial trigger points, and the Shoulder Pain and Disability Index questionnaire were used before and after physical therapy. The duration of physical therapy comprised 3 weeks. Physical therapy of the first group of patients consisted of end-range mobilization and ischemic compression. Patients of the second group performed therapeutic exercises and ischemic compression.

RESULTS

Results: Both groups demonstrated positive dynamics of shoulder joint mobility, Shoulder Pain and Disability Index and pain in trigger points. However, the final results of the studied indicators were better in the first group of patients.

CONCLUSION

Conclusions: Physical therapy based on the combination of end-range mobilization and ischemic compression had a more positive impact on disability and pain indicators for adhesive capsulitis of the shoulder joint and myofascial pain syndrome as compared to the combination of therapeutic exercises and ischemic compression.

The diagnostic value of physical examination tests in adhesive capsulitis: a systematic review

INTRODUCTION

Adhesive capsulitis, a condition marked by pain and stiffness of the shoulder, can have a frustrating clinical course for patients and health care professionals. Despite huge research interest, a universally accepted and used definition of clinical criteria for the diagnosis of adhesive capsulitis is currently still lacking. This systematic review aimed to identify diagnostic values for clinical examinations tests used in the diagnosis of adhesive capsulitis.

EVIDENCE ACQUISITION

A total of 5 electronic databases (PubMed, Web of Science, Embase, Cochrane Central Register of Controlled Trials [CENTRAL] and PEDro) were searched for relevant studies from 2002 until October 2022 using the terms: "adhesive capsulitis AND diagnosis" and "frozen shoulder AND diagnosis." The Downs and Black Checklist (modified) was used to assess the risk of bias. The study protocol was prospectively registered at the International prospective register of systematic reviews (PROSPERO, CRD42022365993).

EVIDENCE SYNTHESIS

The initial database search identified 1799 studies, of which 9 (0.50%) were eventually included in the systematic review. Non-intrusive shoulder range of motion measurements in patients with adhesive capsulitis using the Kinect for Windows (Microsoft, Redmond, WA, USA) showed high correlation with clinical range of motion measurement. Two specific clinical tests, the affected-unaffected shoulder approach of the Coracoid Pain Test and the Distension Test in Passive External Rotation, were identified and presented excellent sensibility and specificity in the diagnosis of adhesive capsulitis, in their original study. Comparison between clinical tests was not possible due to the heterogeneity in clinical tools.

CONCLUSIONS

This systematic review identified several physical examination tests developed for the diagnosis of adhesive capsulitis but could not compare them nor advance a set of clinical diagnostic tests that are scientifically validated. Further research is warranted to obtain validation of clinical diagnosis tools for adhesive capsulitis.

Increased Expression of Adipokines in Patients With Frozen Shoulder

BACKGROUND

Adipokines represent a spectrum of bioactive molecules that could modulate fibroblastic and inflammatory processes. The role of adipokines in the pathogenesis of frozen shoulder (FS), a common musculoskeletal disorder characterized by chronic inflammation, remains obscure.

PURPOSE

To evaluate whether adipokines contribute to the pathogenic mechanisms of FS and to evaluate any potential correlation of adipokines with patients' symptoms.

STUDY DESIGN

Controlled laboratory study.

METHODS

Shoulder capsule specimens were obtained from 10 patients with FS and 10 patients with shoulder instability (control group). The specimens were dyed using hematoxylin and eosin and immunohistochemically assessed with antibodies targeting adipokines, collagen I, collagen III, and tumor necrosis factor α. Immunoreactivity was graded from "no" to "strong" in a blinded manner. Reverse transcription-quantitative real-time polymerase chain reaction (RT-qPCR) analysis was conducted. Before the surgery, patient-reported frequency of pain, severity of pain, stiffness, and shoulder range of motion were documented.

RESULTS

In comparison with the control group, patients with FS had significantly greater pain frequency, pain severity, and stiffness and more limited shoulder range of motion (P < .001). Hematoxylin and eosin- and Masson trichrome-stained samples from the FS group displayed hypercellularity and increased collagen fibers. Immunohistochemistry and RT-qPCR analyses indicated that expression of adipokines was significantly increased in FS capsules compared with the control group. The expression of collagen I, collagen III, and tumor necrosis factor α was also increased in FS capsules. No significant correlation was noted between adipokine expression and patient-reported outcomes in the control group, whereas in patients with FS, adiponectin expression was correlated with pain frequency (r = 0.78; P = .01) and stiffness (r = 0.73; P = .02). Visfatin was also correlated with pain frequency (r = 0.70; P = .02).

CONCLUSION/CLINICAL RELEVANCE

This study indicated a potential role for adipokines in the pathogenesis of FS and demonstrated a correlation between adipokine expression and patients' pain and stiffness.

A randomized clinical trial of glenohumeral joint steroid injection versus suprascapular nerve block in patients with frozen shoulder: a protocol for the Therapeutic Injections For Frozen Shoulder (TIFFS) study

Frozen shoulder is a common, painful condition that results in impairment of function. Corticosteroid injections are commonly used for frozen shoulder and can be given as glenohumeral joint (GHJ) injection or suprascapular nerve block (SSNB). Both injection types have been shown to significantly improve shoulder pain and range of motion. It is not currently known which is superior in terms of relieving patients' symptoms. This is the protocol for a randomized clinical trial to investigate the clinical effectiveness of corticosteroid injection given as either a GHJ injection or SSNB. The Therapeutic Injections For Frozen Shoulder (TIFFS) study is a single centre, parallel, two-arm, randomized clinical trial. Participants will be allocated on a 1:1 basis to either a GHJ corticosteroid injection or SSNB. Participants in both trial arms will then receive physiotherapy as normal for frozen shoulder. The primary analysis will compare the Oxford Shoulder Score (OSS) at three months after injection. Secondary outcomes include OSS at six and 12 months, range of shoulder movement at three months, and Numeric Pain Rating Scale, abbreviated Disabilities of Arm, Shoulder and Hand score, and EuroQol five-level five-dimension health index at three months, six months, and one year after injection. A minimum of 40 patients will be recruited to obtain 80% power to detect a minimally important difference of ten points on the OSS between the groups at three months after injection. The study is registered under ClinicalTrials.gov with the identifier NCT04965376. The results of this trial will demonstrate if there is a difference in shoulder pain and function after GHJ injection or SSNB in patients with frozen shoulder. This will help provide effective treatment to patients with frozen shoulder.

Managing painful shoulder after neurological injury

Shoulder pain is common after neurological injury and can be disabling, lead to poor functional outcomes and increase care costs. Its cause is multifactoral and several pathologies contribute to the presentation. Astute diagnostic skills and a multidisciplinary approach are required to recognise what is clinically relevant and to implement appropriate stepwise management. In the absence of large clinical trial data, we aim to provide a comprehensive, practical and pragmatic overview of shoulder pain in patients with neurological conditions. We use available evidence to produce a management guideline, taking into account specialty opinions from neurology, rehabilitation medicine, orthopaedics and physiotherapy.

Minimal clinically important difference (MCID), substantial clinical benefit (SCB), and patient acceptable symptomatic state (PASS) of upper extremity PROMIS scores in idiopathic adhesive capsulitis

INTRODUCTION

The purpose of this study is to calculate the minimal clinically important difference (MCID), substantial clinical benefit (SCB), and patient acceptable symptom state (PASS) of Patient-Reported Outcomes Measurement Information System (PROMIS) Upper Extremity Computer Adaptive Testing v2.0 (UE), Pain Interference (P-Interference), and Pain Intensity (P-Intensity) in patients treated nonoperatively for idiopathic adhesive capsulitis (IAC).

METHODS

The anchor-based MCID, SCB, and PASS were calculated as the change in PROMIS scores representing the optimal cutoff for a ROC curve with an area under the curve (AUC) analysis. The distribution-based MCID was calculated as a range between the average standard error of measurement multiplied by two different constants: 1 and 2.77. Effect sizes and standardized response means (SRM) were calculated to assess the responsiveness of each PROMIS instrument while regression analyses were performed to identify factors associated with achieving these thresholds.

RESULTS

This study enrolled 115 patients. The anchor-based MCID for PROMIS UE, P-Interference, and P-Intensity was 5.11, 4.16, and 8.16, respectively. The respective SCB was 8.44, 6.65, and 10.05. The respective PASS was 8.47, 7.01, and 10.41. The odds of achieving MCID values in adhesive capsulitis were negatively affected by gender (male), higher forward elevation at the time of presentation, higher pain scores (P-Interference), need for ≥ 2 corticosteroid injections, and a concomitant diagnosis of diabetes.

CONCLUSION

The MCID, SCB, and PASS parameters for PROMIS scores can be utilized to determine the clinical meaningfulness of patient-reported improvements in these instruments during the nonoperative treatment and as a research tool to compare the efficacy of new treatments for adhesive capsulitis.

LEVEL OF EVIDENCE

Level III, basic science study, validation of outcome instruments. Key points • This is the first study to calculate the minimal clinically important difference (MCID), substantial clinical benefit (SCB), and patient acceptable symptomatic state (PASS) for the Patient-Reported Outcome Measurement Information System (PROMIS) Upper Extremity and Pain instruments in patients with idiopathic adhesive capsulitis (IAC) of the shoulder.• This study determined the impact of symptom severity, demographics, and comorbidities on achieving the MCID, SCB, and PASS for PROMIS instruments in IAC patients treated nonoperatively.

A retrospective study of ultrasound-guided intervention for frozen shoulder in the frozen stage

Background

To investigate the clinical value of ultrasound (US)-guided intervention for frozen shoulder (FS) in the frozen stage.

Methods

This study included 40 patients who had primary FS in the frozen stage and were evaluated by US. These 40 patients have all received conservative treatment elsewhere, and no satisfactory results have been achieved, with no improvement in active and passive movement angles, and no improvement in scores within 3 months. Therefore, their previous treatment was set as comparison. All patients underwent US-guided shoulder joint capsule distension by injection of sterilized water. Of these participants, 22 patients with scapulohumeral periarthritis received a compound betamethasone injection, and 14 patients with thickened coracohumeral ligaments (CHLs) underwent acupotomy lysis, and the remaining 4 patients had no extra treatments. The Constant-Murley score (CMS) was evaluated before and after the operation and analysed for each patient.

Results

Before treatment, the indices for the thickening of the subaxillary joint capsule, subacromial bursa (with or without effusion), long head of the biceps brachii tendon (LHBBT) and CHL were 40, 22, 16 and 14, respectively. After treatment, all the indices were significantly decreased (all P < 0.010) except for that of the LHBBT (P = 0.123). The patients' CMSs improved, with the median total CMS increasing from 59 points (interquartile range: 53–64 points) to 86 points (interquartile range: 78–90 points) (P < 0.010). While the internal rotation (Ir) of the shoulder joint did not improve (FDRs < 0.50), abduction, forward flexion (Ff) and external rotation (Er) improved significantly (all FDRs = 1.00).

Conclusion

Compared with conservative treatment, US-guided intervention for FS in the frozen stage is highly effective and of great clinical value.

Single-Site Corticosteroid Injection Is as Effective as Multisite Corticosteroid Injection in the Nonsurgical Treatment of Frozen Shoulder: A Systematic Review With Meta-Analysis of Randomized Controlled Trials

Purpose

To determine whether multisite corticosteroid injection is more effective than a single injection in the nonsurgical treatment of frozen shoulder (FS) via a meta-analysis of randomized controlled trials

Methods

We identified studies that evaluated the efficacy of multisite corticosteroid injections compared with single-site injection for FS. The Embase, PubMed, and Cochrane Library databases were systematically searched from inception to June 5, 2022. Methodologic quality and risk of bias were assessed using the Modified Coleman Methodology Score and the Cochrane Collaboration risk of bias tool, respectively. Visual analog scale scores, abduction, flexion, internal rotation, external rotation, American Shoulder and Elbow Surgeons Assessment Form scores, Constant–Murley Shoulder scores, and complications were extracted. The meta-analysis was conducted with random effects, and 4 time intervals were analyzed: 3 to 4 weeks, 6 to 8 weeks, 12 to 16 weeks, and 24 to 26 weeks

Results

The initial search identified 260 studies, and 5 randomized controlled trials that met the inclusion criteria were included. There were no significant differences in visual analog scale scores at 3 to 4 weeks, 6 to 8 weeks, 12 to 16 weeks, or 24 to 26 weeks. There were no significant differences in flexion or external rotation at 3 to 4 weeks, 6 to 8 weeks, 12 to 16 weeks, or 24 to 26 weeks. Multisite injection performed better in terms of abduction (mean difference –15.66 [–30.03, –1.28], P = .03) and American Shoulder and Elbow Surgeons Assessment Form score (mean difference –10.13 [–19.54, –0.72] P = .03) than single-site injection at 3 to 4 weeks. There were significant differences in internal rotation in favor of the multisite treatment at 3 to 4 weeks, 6 to 8 weeks, 12 to 16 weeks, and 24 to 26 weeks. In addition, there were no significant differences in complications.

Conclusions

Single-site steroid injection is as effective as multisite corticosteroid injection for the nonoperative treatment of FS.

Level of Evidence

Level II, meta-analysis of Level I and II studies.

Arthroscopic rotator interval release for frozen shoulder, comparative study between diabetic and non-diabetic patients

INTRODUCTION

The objective of this study is to evaluate the outcomes of arthroscopic rotator interval release for the treatment of frozen shoulder and compare the results in patients with and without diabetes.

METHODS

thirty-two patients with frozen shoulders were divided into two groups; 19 diabetics and 13 non-diabetics. All patients underwent arthroscopic rotator interval release. The VAS and UCLA score were assessed pre-operatively and post-operatively; after 1, 3, and 12 months and compared between groups.

RESULTS

The VAS and UCLA score was significantly improved in both groups during follow-up intervals (p < 0.01). There was no significant difference between diabetic and non-diabetic patients in VAS and UCLA scores during follow-up times (p-values > 0.05).

CONCLUSION

Arthroscopic rotator interval release provides significant improvement of frozen shoulder with no difference in results between diabetic and non-diabetic patients.

LEVEL OF EVIDENCE

Level 2; Prospective Comparative study.

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.

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.