Research Review By Dr. Josh Plener©


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Date Posted:

September 2020

Study Title:

Pain-related beliefs are associated with arm function in persons with frozen shoulder


De Baets L, Matheve T, Traxler J, et al.

Author's Affiliations:

REVAL Rehabilitation Research, Faculty of Rehabilitation Sciences, Hasselt University, Diepenbeek, Belgium; Health Psychology Research, Faculty of Psychology and Educational Sciences, Leuven, Belgium; Experimental Health Psychology, Faculty of Psychology and Neuroscience, Mastricht University, The Netherlands.

Publication Information:

Shoulder and Elbow 2020; DOI: 10.1177/1758573220921561

Background Information:

Frozen shoulder is characterized by decreased active and passive shoulder ranges of motion, pain during joint movement and night pain (1, 2). Typically, there is decreased range of motion in all directions, most notably during shoulder external rotation with an elevated arm (2). In addition, it is common that greater pain is experienced at the end of the available joint range.

The incidence of frozen shoulder in the general population is approximately 5% (2), however, due to a lack of clear diagnostic criteria, the true incidence and prevalence rates are unknown. Clinically, frozen shoulder is associated with diabetes, thyroid disorders, cardiovascular disease and Dupuytren disease (3). Nevertheless, a significant number of frozen shoulder cases are diagnosed as idiopathic in nature and therefore, treatment largely focuses on symptom modification and functional enhancement.

Despite the self-limiting prognosis of frozen shoulder, mild symptoms may persist for several years (each case is different!). Clinically, this can result in a reduction of arm function during daily activities, having a significant impact on patients. Therefore, identifying factors that lead to this reduction in movement is important. Recent systematic reviews have demonstrated an association between pain related beliefs and disability in shoulder pain patients receiving surgery or conservative treatment (4-6). As well, pain self-efficacy appears to be an important factor associated with arm function for patients who received physiotherapy for their shoulder complaint (7, 8). This demonstrates a link between confidence in performing a task and a person’s perceived function.

Recently, research has suggested psychological factors such as anxiety or pain-related fear could possibly contribute to muscle guarding, leading to decreased glenohumeral motion in patients with frozen shoulder (9). As a result of the long-lasting pain and dysfunction in patients with frozen shoulder, it is of interest to understand the role of protective versus unhelpful pain-related beliefs underlying reduced arm function. Within the Fear Avoidance Model, a painful experience is believed to initiate catastrophic thoughts about pain, resulting in pain-related fear and avoidance behavior. This avoidance behavior can, of course, lead to decreased function (10).

The primary aim of this study is to explore the association between pain-related beliefs and perceived arm function in patients with frozen shoulder. Secondarily, this study set out to also understand the role pain-related beliefs play in the variance of perceived arm function in patients. It was hypothesized that a significant portion of the variance will be linked to pain-related fear, catastrophizing and pain self-efficacy.

Pertinent Results:

85 subjects participated in this study, having an average duration of symptoms of 4.6 months.

The results of this study suggest that beliefs towards pain or painful activities are associated with perceived arm function. The associations for each outcome measure fell into the category of a weak or moderate association, as outlined below.

Weak association with perceived arm function:
  • Pain catastrophizing and perceived arm function (r = 0.45)
  • Pain-related fear and pain-self efficacy (-0.46)
Moderate association with perceived arm function:
  • Pain related fear and perceived arm function (r = 0.51)
  • Pain-self efficacy and perceived arm function (r = -0.69)
  • Pain related fear and pain catastrophizing (r = 0.55)
  • Pain-self efficacy and pain catastrophizing (r = -0.58)
Regression Analysis

A regression analysis was used to address the secondary aim of this study. With the inclusion of only the control variables in the model, 31% of variance in arm function was explained. When pain-related fear, pain catastrophizing and pain self-efficacy were added to the model, pain-related fear and pain self-efficacy were significant contributors. This explained 57% of the variance in perceived arm function.

Clinical Application & Conclusions:

The biopsychosocial approach to patient care encourages healthcare professionals to acknowledge the role psychosocial factors play in an individual’s clinical presentation. For clinicians, this study adds to the body of literature, and is a first step in understanding the role of pain-related beliefs in disability experienced with frozen shoulder. In clinic, screening tools such as the ones used in this study can be completed by patients to tease out if pain-related beliefs are present, allowing for a comprehensive, holistic view of the patient.

The average Pain Catastrophizing Scale (PCS) score in this study was ~14, which is low compared to a cut-off value of 30 in other studies where PCS scores were associated with clinical relevance (11). This may indicate that patients with frozen shoulder may not significantly demonstrate catastrophic ideations regarding their pain experience (11). This is also potentially explained via previous research, which reported that optimism and hope are inversely related to pain catastrophizing. Therefore, it’s possible that the predictable course of frozen shoulder recovery results in increased hope and optimism, thereby reducing pain catastrophizing.

In the literature, the association between pain-related fear and physical function are mixed. Some studies have found no predictive value for pain-related fear on shoulder function, while others, including this study, have supported this concept (12, 13). This finding is not surprising, as patients with frozen shoulder have long lasting movement restrictions, with increasing pain typically towards the end ranges of motion. Therefore, this avoidance behavior to painful activities might be interpreted as a normal reaction in the context of persistent pain (14).

The strongest association with perceived arm function was pain self-efficacy. Self-efficacy – to review – is a person’s belief in their ability to succeed in a specific situation or to accomplish a task (15). Individuals with a high self-efficacy have a positive mindset with accomplishing and succeeding in tasks (16). Some examples of pain self-efficacy beliefs include beliefs regarding their ability to control pain and negative emotions associated with it, to perform daily activity despite the pain and to implement advice received by healthcare professionals. The strong association between arm function and pain self-efficacy suggests that an individual’s perception of their ability to perform activities is indeed related to arm function.

One possibility for the high association between pain self-efficacy and perceived arm function may be due to overlapping questions in the Pain Self-Efficacy Questionnaire (PSEQ) and the Disability of the Arm, Shoulder and Hand Questionnaire (DASH). For example, the DASH asks to rate your ability to open a jar, prepare a meal and do heavy household chores, which possibly resembles PSEQ questions on confidence to do most household chores despite the pain. However, the item overlap appears to be minimal as when the overlapping questions were removed and re-inputted into the regression analysis, the variation in arm function was minimally reduced to 55%.

Research surrounding pain-related beliefs allows researchers and clinicians to better understand prognostic factors for recovery, allowing them to provide remediation strategies to improve treatment outcomes. For example, patients can be educated and informed of what to expect in their recovery (i.e. understanding pain, unhelpful thoughts, coping styles and goal setting) in order to assist patients with inadequate pain-related beliefs (17-19).

Future research is required to further evaluate the relationship between pain-related beliefs and arm function. Currently, a high self-efficacy appears to be the most relevant and is something all clinicians should be striving for with their patients. Empowering patients with frozen shoulder to take control of their own health and allow them to effectively self-manage and goal set is something that will be important to study in the future.

Study Methods:

Participants were recruited by the researchers via orthopedic surgeons, private general practitioners’ and physical therapists’ practices in Belgium during the period from February 2017 to December 2018.

Inclusion criteria:
  • Adults with unilateral, clinically diagnosed frozen shoulder.
  • Passive shoulder ROM restriction of 25% or more in at least two directions compared to the healthy, unaffected shoulder and at least 50% external rotation restriction on the affected shoulder (2).
  • Pain and restricted ROM present for at least two months.
  • Symptoms have reached a plateau or are becoming worse (2).
  • Gradual onset of pain and stiffness.
Exclusion criteria:
  • Previous surgical procedure for their frozen shoulder.
  • Presence of a systemic or neurological disease.
Once participants were deemed eligible to participate in the study, they filled out questionnaires including the Disability of the Arm, Shoulder and Hand Questionnaire (DASH), Tampa Scale of Kinesiophobia (TSK-11), Pain Catastrophizing Scale (PCS), Pain Self-Efficacy Questionnaire (PSEQ) and the Numeric Pain Rating Scale (NPRS). The DASH was used to determine perceived arm function, the TSK-11 was used to determine pain-related fear, the PCS was used to determine pain catastrophizing, the PSEQ was used to determine self-efficacy beliefs and the NPRS was used to determine shoulder pain intensity over the last week.

Correlation coefficients were calculated to determine the association between pain related fear, pain catastrophizing, pain self-efficacy and perceived arm function. The correlation coefficients were considered very weak if between 0-0.29, weak if between 0.3–0.49, moderate if between 0.5–0.69, high if between 0.7-0.89 and very high if between 0.9-1.0 (20).

In order to determine the variance in perceived arm function, regression analysis was utilized. Initially, multiple control variables including sex, age, pain intensity and duration of symptoms were added to the model to determine the variance in perceived arm function by these variables. Following this, the contribution in the variance of perceived arm function by pain-related fear, pain catastrophizing and pain self-efficacy was assessed using a multiple linear regression model with the DASH score as the dependent variable.

Study Strengths / Weaknesses:

  • This is the first study (to our knowledge) to assess pain related beliefs in a frozen shoulder population.
  • The claims presented in the article are in-line with, and suitable for the cross-sectional study design used.
  • There is no gold standard for the diagnosis of frozen shoulder, therefore, it is possible other shoulder conditions were inadvertently included in the study.
  • Subjective arm function was used rather than objective functional measures such as physical tests. These two constructs may have resulted in different arm function scores.
  • The cross-sectional study design does not allow for causal conclusions to be drawn.

Additional References:

  1. Walmsley S, Osmotherly PG and Rivett DA. Movement and pain patterns in early stage primary/idiopathic adhesive capsulitis: a factor analysis. Physiotherapy 2014; 100: 336–343.
  2. Kelley MJ, Shaffer MA, Kuhn JE, et al. Shoulder pain and mobility deficits: adhesive capsulitis. J Orthop Sports Phys Ther 2013; 43: A1–A31.
  3. Ryan V, Brown H, Minns Lowe CJ, et al. The pathophysiology associated with primary (idiopathic) frozen shoulder: a systematic review. BMC Musculoskelet Disord 2016; 17: 340.
  4. Coronado RA, Seitz AL, Pelote E, et al. Are psychosocial factors associated with patient-reported outcome measures in patients with rotator cuff tears? A systematic review. Clin Orthop Relat Res 2018; 476: 810–829.
  5. De Baets L, Matheve T, Meeus M, et al. The influence of cognitions, emotions and behavioral factors on treatment outcomes in musculoskeletal shoulder pain: a systematic review. Clin Rehab 2019; 33: 980–991.
  6. Martinez-Calderon J, Struyf F, Meeus M, et al. The association between pain beliefs and pain intensity and/or disability in people with shoulder pain: a systematic review. Musculoskelet Sci Pract 2018; 37: 29–57.
  7. Chester R, Jerosch-Herold C, Lewis J, et al. Psychological factors are associated with the outcome of physiotherapy for people with shoulder pain: a multicenter longitudinal cohort study. Brit J Sports Med 2018; 52: 269–275.
  8. Chester R, Khondoker M, Shepstone L, et al. Self-efficacy and risk of persistent shoulder pain: results of a Classification and Regression Tree (CART) analysis. Brit J Sports Med 2019; 53: 825–834.
  9. Hollmann L, Halaki M, Kamper SJ, et al. Does muscle guarding play a role in range of motion loss in patients with frozen shoulder? Musculoskelet Sci Pract 2018; 37: 64–68.
  10. Vlaeyen JW, Crombez G and Linton SJ. The fear-avoidance model of pain. Pain 2016; 157: 1588–1589.
  11. Sullivan MJL, Bishop SR and Pivik J. The Pain Catastrophizing Scale: Development and validation. Psychological Assessment 1995; 7: 524–532.
  12. Clausen MB, Witten A, Holm K, et al. Glenohumeral and scapulothoracic strength impairments exists in patients with subacromial impingement, but these are not reflected in the shoulder pain and disability index. BMC Musculoskelet Disord 2017; 18: 302.
  13. Lentz TA, Barabas JA, Day T, et al. The relationship of pain intensity, physical impairment, and pain-related fear to function in patients with shoulder pathology. J Orthop Sports Phys Ther 2009; 39: 270–277. 2009/04/07.
  14. Meulders A. From fear of movement-related pain and avoidance to chronic pain disability: a state-of-the-art review. Curr Opin Behav Sci 2019; 26: 130–136.
  15. Bandura A. Self-efficacy: toward a unifying theory of behavioral change. Psychol Rev 1977; 84: 191–215.
  16. Marks R, Allegrante JP and Lorig K. A review and synthesis of research evidence for self-efficacy-enhancing interventions for reducing chronic disability: implications for health education practice (part I). Health Promot Pract 2005; 6: 37–43.
  17. van Erp RMA, Huijnen IPJ, Jakobs MLG, et al. Effectiveness of primary care interventions using a biopsychosocial approach in chronic low back pain: a systematic review. Pain Pract 2019; 19: 224–241.
  18. Sawyer EE, McDevitt AW, Louw A, et al. Use of pain neuroscience education, tactile discrimination, and graded motor imagery in an individual with frozen shoulder. J Orthop Sports Phys Ther 2018; 48: 174–184.
  19. Watson JA, Ryan CG, Cooper L, et al. Pain neuroscience education for adults with chronic musculoskeletal pain: a mixed-methods systematic review and meta-analysis. J Pain 2019; 20: 1140.e1–1140.e22.
  20. Rumsey DJ. Statistics for dummies. 2nd ed. Indiana: Wiley Publishing Inc., 2016.