Does muscle guarding play a role in range of motion loss in patients with frozen shoulder?

STUDY DESIGN: Observational: cross-sectional study. BACKGROUND: Idiopathic frozen shoulder is a common cause of severe and prolonged disability characterised by spontaneous onset of pain with progressive shoulder movement restriction. Although spontaneous recovery can be expected the average length of symptoms is 30 months. Chronic inflammation and various patterns of fibrosis and contracture of capsuloligamentous structures around the glenohumeral joint are considered to be responsible for the signs and symptoms associated with frozen shoulder, however, the pathoanatomy of this debilitating condition is not fully understood. OBJECTIVES: To investigate the feasibility of a muscle guarding component to movement restriction in patients with idiopathic frozen shoulder. METHODS: Passive shoulder abduction and external rotation range of motion (ROM) were measured in patients scheduled for capsular release surgery for frozen shoulder before and after the administration of general anaesthesia. RESULTS: Five patients with painful, global restriction of passive shoulder movement volunteered for this study. Passive abduction ROM increased following anaesthesia in all participants, with increases ranging from approximately 55°-110° of pre-anaesthetic ROM. Three of these participants also demonstrated substantial increases in passive external rotation ROM following anaesthesia ranging from approximately 15°-40° of pre-anaesthetic ROM. CONCLUSION: This case series of five patients with frozen shoulder demonstrates that active muscle guarding, and not capsular contracture, may be a major contributing factor to movement restriction in some patients who exhibit the classical clinical features of idiopathic frozen shoulder. These findings highlight the need to reconsider our understanding of the pathoanatomy of frozen shoulder. LEVEL OF EVIDENCE: Level 4.

Revision of the Shoulder Normalization Tests is required to include rhomboid major and teres major.

The four "Shoulder Normalization Tests" were found previously to be a parsimonious set of isometric tests that produce maximal voluntary isometric contractions (MVIC) in the supraspinatus, infraspinatus, subscapularis, trapezius, serratus anterior, deltoid, latissimus dorsi, and pectoralis major [Boettcher et al. (2008). J Orthop Res 26:1591-1597]. However, these tests have not been validated for rhomboid major and teres major. In the current study, these Shoulder Normalization Tests were evaluated and compared to three other tests that could possibly elicit maximum activity in rhomboid major and teres major: abduction/extension in 90° abduction; adduction at 90° abduction; and extension in 30° abduction. No statistical difference was found in the mean activation of rhomboid major and teres major in these additional MVIC tests compared to the Shoulder Normalization Tests. However, the extension MVIC test produced maxima for at least 50% of subjects in rhomboid major, teres major, and latissimus dorsi. We concluded that the original Shoulder Normalization Tests should be expanded to include the extension MVIC test. The EMG normalization reference value for any of the above muscles would be the maximum EMG level generated across these Revised Shoulder Normalization Tests.

Shoulder proprioception is associated with humeral torsion in adolescent baseball players.

OBJECTIVES: To determine the relationship between the amount of humeral torsion and a measure of active proprioception in adolescent male throwing athletes. DESIGN: Cross-sectional laboratory study with uninjured subjects. SETTING: University of Sydney and NSW Institute of Sport. PARTICIPANTS: Participants were 16 adolescent male baseball players (15.0-18.1 years old, SD=16.3) holding baseball scholarships at the NSW Institute of Sport. MAIN OUTCOME MEASURES: The main outcome measures, active proprioception (shoulder rotation, in 90 degrees of arm abduction moving towards external rotation, using the Active Movement Extent Discriminating Apparatus) and humeral torsion (using an ultrasound-assisted method), were measured bilaterally. RESULTS: A strong (r=0.88) and significant (p=0.001) correlation was found between increasing humeral retrotorsion and better active proprioceptive acuity in the non-dominant arm, while the relation was weaker (r=0.41) and did not reach statistical significance (p=0.120) for the dominant arm. CONCLUSIONS: A cognitive processing capacity model, which suggests that greater humeral retrotorsion reduces neural processing requirements, has been proposed to explain the direct relationship between proprioceptive acuity and humeral retrotorsion.

A randomized, controlled clinical trial of a treatment for shoulder pain.

BACKGROUND AND PURPOSE: The aim of this study was to evaluate the efficacy of a physical therapy approach to the treatment of shoulder pain. Subjects. Sixty-six volunteers with shoulder pain believed to be of local mechanical origin were randomly allocated to either a treatment group or a control group. METHODS: Subjects in the treatment group received 1 month of physical therapy aimed at restoring function of their shoulder muscles. Subjects in the control group received no treatment. Outcome measurements of pain intensity, range of motion (ROM), isometric muscle force, functional impairment, and self-perception of improvement were obtained by blinded assessment. RESULTS: Subjects in the treatment group showed improvement in pain-free abduction and flexion ROM, functional impairment, and self-perception of improvement. The control group deteriorated slightly over the experimental period in ROM and functional impairment measures. CONCLUSION AND DISCUSSION: These results suggest that the physical therapy approach used in this study is effective in improving shoulder function in subjects experiencing pain of mechanical origin. The results also provide little evidence of spontaneous recovery over a 1-month period.