The influence of posterior glenohumeral joint capsule tightness and humeral retroversion on clinical measurements

No Evidence of Short-term Changes in Muscle Activity Elicited by Dry Needling in Chronic Unilateral Shoulder Pain Patients

OBJECTIVE

The aim of the study was to assess short-term changes in shoulder muscle activity elicited by dry needling in chronic unilateral shoulder pain (USP) patients.

METHODS

A randomized, double-blind, placebo-controlled clinical trial was conducted, in which 30 volunteers with USP were recruited and randomly assigned to either real or sham dry needling conditions. Pain intensity scores, pressure pain threshold, glenohumeral internal rotation angles, and electromyographic activity during isotonic shoulder tasks (shoulder flexion and extension) were assessed before, immediately, and 72 hours after the intervention in the infraspinatus and deltoid muscles.

RESULTS

A single application of real dry needling resulted in lower pain intensity scores and a larger range in glenohumeral internal rotation 72 hours after the intervention in comparison with sham dry needling. No differences in pressure pain threshold or muscle activity were observed due to the intervention.

DISCUSSION

A single application of real dry needling resulted in clinically significant changes in the short term. No differences were detected in muscle activation in the infraspinatus or deltoid muscles. Complementary interventions and longer follow-up times may be required to observe changes in muscle activity.

Effect of Posterior Capsule Tightness and Humeral Retroversion on 5 Glenohumeral Joint Range of Motion Measurements: A Cadaveric Study

BACKGROUND

Altered glenohumeral joint range of motion can be caused by increased humeral retroversion (HR) and/or posterior capsule tightness (PCT). To make informed clinical decisions, it is vital to understand how HR and PCT alterations, individually and in combination, affect joint range of motion measurements.

PURPOSE

To evaluate the effect of experimental tissue alterations on clinical range of motion measures.

STUDY DESIGN

Controlled laboratory study.

METHODS

Five clinical measurements were quantified in 8 fresh-frozen cadavers under 4 experimentally created conditions: baseline (no alterations), HR condition (20° increase in HR by transecting the bone), PCT condition (20% decrease in length via thermal energy), and PCT + HR combined. Clinical measurements included bicipital forearm angle, low flexion, glenohumeral internal and external rotation, and horizontal adduction. All measurements were taken by the same blinded tester. Separate 1-factor repeated measures analyses of variance were used to evaluate the effect of the alterations on each clinical measurement.

RESULTS

There was a significant main effect of condition for bicipital forearm angle ( P = .02, F = 4.03), low flexion ( P = .02, F = 3.86), internal rotation ( P = .03, F = 3.65), and external rotation ( P < .001, F = 15.15) but not for horizontal adduction ( P = .29, F = 1.33). The HR condition resulted in a decreased bicipital forearm angle of 16.1° and 15.8° as compared with the PCT and PCT + HR conditions, respectively. When compared with baseline, the PCT + HR condition decreased the low flexion test by 13.5°, and the HR condition decreased internal rotation range of motion by 14.2°. All conditions increased external rotation when compared with baseline.

CONCLUSION

Greater measurement changes were noted in both HR conditions, suggesting that bony alterations influence motion to a greater extent than posterior capsule alterations.

CLINICAL RELEVANCE

Clinicians should be aware that humeral retroversion will influence the measurement of posterior shoulder tightness.