Absolute and Relative Reliability of Pressure Pain Threshold Assessments in the Shoulder Muscles of Participants With and Without Unilateral Subacromial Impingement Syndrome.

OBJECTIVE: The purpose of this study was to determine the relative and absolute reliability of the pressure pain threshold (PPT) in the shoulder muscles of participants with and without unilateral subacromial impingement syndrome. METHODS: Study of intraday intra- and interrater and interday intrarater reliability. Fifty-two participants symptomatic for unilateral subacromial impingement syndrome were divided into 2 groups (SG1 and SG2) of 26 participants each, and 26 participants asymptomatic for shoulder pain took part in the study. Two raters assessed the PPT in 4 shoulder muscles. Each rater assessed symptomatic (SG1) and asymptomatic participants twice on the same day, and one of the raters on 2 different days (SG2). The intraclass correlation coefficient, standard error of measurement (SEM95% and SEM%), and minimum detectable change (MDC95% and MDC%) were calculated. RESULTS: Relative reliability was good or excellent for all assessments, as well as for both groups and raters (intraclass correlation coefficient: 0.87-0.98). The SEM95% values for intra- and interday intrarater measures were between 0.43 and 1.50 kgf/cm2 and SEM% between 6.76 and 12.86%, whereas MDC95% values ranged from 0.60 to 2.12 kgf/cm2 and MDC% from 9.56 to 18.18%. In interrater measures, SEM95% was between 0.58 and 0.77 kgf/cm2 and SEM% between 10.10% and 13.71%, whereas MDC95% varied from 0.82 to 1.08 kgf/cm2 and MDC% from 14.29% to 19.39%. CONCLUSION: Relative reliability was good or excellent. This study presents absolute reliability values that could be used as a reference in the clinical use of PPT.

Inter- and Intraexaminer Reliability in Identifying and Classifying Myofascial Trigger Points in Shoulder Muscles.

OBJECTIVE: To determine inter- and intraexaminer reliability of examiners without clinical experience in identifying and classifying myofascial trigger points (MTPs) in the shoulder muscles of subjects asymptomatic and symptomatic for unilateral subacromial impact syndrome (SIS). DESIGN: Within-day inter- and intraexaminer reliability study. SETTING: Physical therapy department of a university. PARTICIPANTS: Fifty-two subjects participated in the study, 26 symptomatic and 26 asymptomatic for unilateral SIS. INTERVENTIONS: Two examiners, without experience for assessing MTPs, independent and blind to the clinical conditions of the subjects, assessed bilaterally the presence of MTPs (present or absent) in 6 shoulder muscles and classified them (latent or active) on the affected side of the symptomatic group. Each examiner performed the same assessment twice in the same day. MAIN OUTCOME MEASURES: Reliability was calculated through percentage agreement, prevalence- and bias-adjusted kappa (PABAK) statistics, and weighted kappa. RESULTS: Intraexaminer reliability in identifying MTPs for the symptomatic and asymptomatic groups was moderate to perfect (PABAK, .46-1 and .60-1, respectively). Interexaminer reliability was between moderate and almost perfect in the 2 groups (PABAK, .46-.92), except for the muscles of the symptomatic group, which were below these values. With respect to MTP classification, intraexaminer reliability was moderate to high for most muscles, but interexaminer reliability was moderate for only 1 muscle (weighted κ=.45), and between weak and reasonable for the rest (weighted κ=.06-.31). CONCLUSIONS: Intraexaminer reliability is acceptable in clinical practice to identify and classify MTPs. However, interexaminer reliability proved to be reliable only to identify MTPs, with the symptomatic side exhibiting lower values of reliability.

Relationships Between Active Myofascial Trigger Points and Depressive Symptoms and Physical and Clinical Characteristics of Individuals With Shoulder Pain: A Cross-sectional Study.

Objective: The purpose of this study was to evaluate relationships between the presence and number of active myofascial trigger points (MTPs) in shoulder muscles and physical and demographic characteristics, depressive symptoms, pain and function, range of motion (ROM), and strength in individuals with shoulder pain. Methods: Fifty-eight individuals were assessed for physical and demographic characteristics, depressive symptoms, shoulder pain and function, MTPs (upper and lower trapezius, infraspinatus, and supraspinatus), shoulder ROM and strength test, and pain during ROM and strength test. Relationships were verified using point-biserial (rpb), Spearman correlation test, and multiple linear regression analysis. Results: We found weak to moderate (P < .05) correlations between presence and number of MTPs and depressive symptoms (rpb, 0.28-0.32), pain during ROM (rpb, 0.36-0.40), pain during strength test (rpb, 0.29-0.38), and shoulder function (rpb, -0.29 to 0.33) and strength (rpb, 0.26-0.34). MTPs in the infraspinatus contributed 10% (R² = 0.10; P < .05) to depressive symptoms; in the upper and lower trapezius contributed 27% (R² = 0.27; P < .05) to pain during internal rotation ROM; in the upper trapezius contributed 15% (R² = 0.15; P < .01) to pain during internal rotation strength test and 14% to pain during internal rotation ROM (R² = 0.14; P < .01); and in the supraspinatus contributed 17% (R² = 0.17; P < .01) to pain during external rotation ROM. Conclusion: This study found that MTPs in individuals with shoulder pain contributed to depressive symptoms and pain during internal and external rotation ROM and internal rotation strength test.