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.

Energetic and Metabolic Power Demands of National Rugby League Match-Play.

The purpose of this study was to apply a time-motion model to estimate and describe the energy expenditure and metabolic power demands of playing positions in elite rugby league match-play, utilizing Global Positioning System (GPS) devices. 18 elite rugby league players participated in this study. Players' positional groups included: outside backs (n=59 files, n=4 players), adjustables (n=74 files, n=4 players), wide-running (n=104 files, n=7 players) and hit-up forwards (n=36 files, n=3 players). Outside backs expended the greatest total energy (40.1±5.0 kJ·kg(-1)) per match, equivalent to 8.1%, 26.6% and 61.9% greater energy than adjustables, wide-running and hit-up forwards, respectively. Adjustables attained an anaerobic index 7.3% higher than wide-running forwards, 19.7% higher than hit-up forwards (p=0.001) and 43.2% higher than outside backs (p<0.001). Wide-running forwards achieved an anaerobic index (0.34±0.04) 11% and 32.8% higher than hit-up forwards (p=0.001) and outside backs (p<0.001), respectively. Mean power of adjustables (10.0±0.9 W·kg(-1)) was significantly higher than all other groups (outside backs: 28.8%, 7.8±1.0; hit-up: 12.4%, 8.9±0.6; and wide-running: 8.7%, 9.2±0.7 forwards) (p<0.001). Energetics indices indicated differing metabolic demands for all positional groups, suggesting position-specific conditioning drills are required to replicate the energetic demands of match-play.

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.