e34 2010 Asics Conference of Science and Medicine in Sport / Journal of Science and Medicine in Sport 13S (2010) e1–e107

when compared with normal data, contrasting with post-rehabilitation data, where variability extended beyond thelevels displayed in the control group. Conclusions: Basedon functional outcomes, this study provides support for con-servative rehabilitation in MDI. The dynamic systems theorywould suggest that the broader spectrum of EMG variabil-ity identified could be associated with the improved functionoutput. Given the associated structural deficits in MDI, it ispotentially unreasonable to expect MDI subjects to replicatethe activation patterns previously noted in an asymptomaticpopulation. Allowing patients with MDI to move with morethan one motor strategy disperses soft tissue loads and dimin-ishes repetitive microtrauma. Clinically, the notion of motorvariability could be beneficial when establishing a functionalrehabilitation program. Future larger scale EMG studiesare needed to generate a more sound understanding of thedynamic systems approach and the relationship of variabilitywith optimal functionality.

doi:10.1016/j.jsams.2010.10.532

72

Subscapularis does not stabilize the glenohumeral jointduring throwing

C. Boettcher ∗, K. Ginn, I. Cathers

The University of Sydney, Australia

During throwing the rotator cuff muscles are consideredto function as stabilizers of the shoulder joint as well as accel-erators and decelerators of the humerus. However, a recentstudy examining isometric shoulder rotation in an abductedposition indicates that the rotator cuff muscles are unlikelyto be performing a stabilizer function in this position. Fur-thermore, research from this same laboratory has shown thatco-contraction of the rotator cuff is not necessary to pro-vide dynamic shoulder stability in all planes of movement.During flexion and extension the rotator cuff muscles con-tract reciprocally, with infraspinatus and supraspinatus activeduring flexion and subscapularis active during extension, toprevent anterior and posterior displacement of the humeralhead respectively. Past EMG research comparing shouldermuscle activity in normal pitchers and pitchers with ante-rior instability during the acceleration phase of the pitchdemonstrated significantly lower activity in latissimus dorsiin the unstable pitchers with no significant difference in pos-terior cuff (infraspinatus and supraspinatus) activity levelsbetween normal and unstable groups. These authors wereunable to provide a clear explanation for the instability inlight of this altered shoulder muscle activity. It is proposedfrom the results of our recent research that the reducedlatissimus dorsi activity may be the cause of anterior insta-bility. That is, both subscapularis and pectoralis major maypotentially cause anterior translation of the humeral headduring the acceleration phase. Activity in the posterior cuff

(external rotators) to prevent this anterior translation wouldbe counterproductive to the generation of maximum inter-nal rotation torque required during the acceleration phase.Contraction of latissimus dorsi, on the other hand, couldprevent anterior translation of the humeral head during theacceleration phase of pitching while contributing to the gen-eration of internal rotation torque. Significantly lower activityin latissimus dorsi would, therefore, result in an inabilityto produce enough counterbalancing force to prevent pec-toralis major and subscapularis from producing some anteriorhumeral head translation resulting in the symptoms of ante-rior shoulder instability. These findings have implications forthe understanding and rehabilitation of throwers with shoul-der instability.

doi:10.1016/j.jsams.2010.10.533

73

The reliability of fixed versus handheld dynamometer forshoulder strength testing

N. Beshay 1,2,∗, P. Lam 1,2, G. Murrell 1,2

1 St George Hospital Orthopaedic Research Institute,Australia2 The University of New South Wales, Australia

Background: Reliable measurements of shoulder strengthare important in assessing rotator cuff integrity. Hand-helddynamometry (HHD) is more objective and reliable thanthe traditional manual muscle test. However, the reliabil-ity of HHD may be limited by examiner strength. A fixedstrength assessment device may offer a solution to this poten-tial problem. Aim: To determine if a fixed strength assessmentdevice (made by the Orthopaedic Research Institute) ismore reliable than HHD when measuring the strength offive shoulder movements (internal rotation, external rotation,abduction-supraspinatus, lift-off and adduction). Materialsand methods: Twelve asymptomatic and 11 symptomatic sub-jects participated in the intra-rater reliability assessment. Foreach subject, the strength of five shoulder movements wastested three times using HHD and three times using the fixeddevice by the same examiner. Eleven asymptomatic subjectsand 10 symptomatic subjects participated in the inter-raterreliability assessment. Each of three examiners tested theshoulder strength of each subject, once using HHD andonce using the fixed device. Intraclass correlation coefficients(ICCs) were calculated to assess reliability and Bland-Altmanplots were constructed to identify any associations betweensubject strength and reliability of measurements. Results:Average ICC values for intra-rater testing for all five move-ments were 0.97 for asymptomatic subjects and 0.94 forsymptomatic subjects using the fixed strength device. Whentested with HHD, average ICC values were 0.95 and 0.94respectively. Average ICC values during inter-rater testingfor all five movements was 0.93 for asymptomatic subjects

2010 Asics Conference of Science and Medicine in Sport / Journal of Science and Medicine in Sport 13S (2010) e1–e107 e35

and 0.92 for symptomatic subjects using the fix strengthdevice and 0.89 and 0.93 for HHD. The inter-rater reliabilityof HHD dropped to 0.83 when the subject’s supraspinatusstrength was greater than 100 N. Conclusion: HHD is a reli-able method of measuring shoulder strength in the clinicalsetting. However, when several examiners are testing thesupraspinatus strength of stronger subjects, stabilising thedynamometer provides more reliable results.

doi:10.1016/j.jsams.2010.10.534

74

Expression of neuronal markers in frozen shoulder

C. Xu 1, F. Bonar 2, G. Murrell 1,∗

1 St George Hospital Orthopaedic Research Institute,Australia2 Douglas Hanley Moire Pathology, Australia

Frozen shoulder is a condition characterized by pain andloss of motion of the shoulder. It was first described by Cod-man in 1934, however the aetiology of this disease remainsunclear and our understanding of the pathogenesis, and whyit is so painful is undetermined. The aim of this study wasto evaluate the innervation pattern of the synovium and cap-sule of frozen shoulder. Methods: Following ethics approvalshoulder capsular samples were collected from patientsundergoing arthroscopic shoulder capsular release for frozenshoulder (n = 8). Control capsular samples were collectedfrom patients undergoing rotator cuff repair (n = 10). Clin-ical symptoms were recorded. Tissue samples were analysedusing histological staining, and immunohistochemical anal-ysis using antibodies against a general nerve marker (proteingene product 9.5, PGP9.5), a nerve growth marker (growthassociated protein 43, GAP43), a nerve growth factor recep-tor p75, an endothelial cell marker (CD34). Results: Thecapsular tissue of patients with frozen shoulder was redand thick at arthroscopy. Morphological analysis showedsynovial and subsynovial oedema with hypercellularity andhypervascularity. The increased vascularity was confirmed bystrongly positive CD34 immunostaining. Increased expres-sion of nerve growth factor receptor p75 was also found infrozen shoulder samples compared to controls. The pres-ence of PGP9.5-positive and GAP43-positive nerves wassignificantly higher in frozen shoulder samples (2.8 ± 0.2and 2.4 ± 0.4 per field) than in the controls (1.6 ± 0.3 and1.3 ± 0.3 per field; p < 0.01 and p < 0.05). Conclusion: Toour knowledge this is the first time significantly increasedexpression of nerve growth factor receptor and new nervefibres have been found in the shoulder capsular tissue ofpatients with frozen shoulder compared with those withouta frozen shoulder. The increased expression of nerve growthfactor receptor and new nerves in the capsular tissue sug-gest that the in-growth of new nerves to the shoulder capsuleis an important event in the pathogenesis of frozen shoul-

der and may help explain the often severe pain in frozenshoulder.

doi:10.1016/j.jsams.2010.10.535

75

Arthroscopic rotator cuff repair: Clinical outcome of 606patients

D. Biggs ∗, B. Haviv, E. Dolev, M. Haber, L. Mayo

Central West Orthopaedics and Sports Injuries, Australia

During the last decade arthroscopic repair has evolvedto become common practice in the surgical treatment ofsymptomatic rotator cuff tendon tears. This paper reports theresults of a consecutive series of patients who underwentarthroscopic rotator cuff repair surgery. All patients wereindependently assessed pre and post operatively utilizing theUCLA scoring system. All procedures were performed bya single surgeon, with a minimum of one year follow-up.Operative details were noted, including patient age, tear size,type of repair performed and concomitant procedures per-formed. Overall, 87% of patients had a good-excellent result.The results were found to be independent of tear size, tearconfiguration and concomitant procedures performed. Thisprospective study is one of the largest series of arthroscopicrotator cuff repairs reported. According to our results, 87%of patients who underwent arthroscopic rotator cuff repairhave maintained good clinical outcomes up to 8 years aftersurgery.

doi:10.1016/j.jsams.2010.10.536

76

A comparative study of arthroscopic and open rotatorcuff repair outcomes of 400 patients followed for two yearsor longer

J. Walton ∗, G. Murrell

St George Hospital Orthopaedic Research Institute,Australia

Introduction: Open surgery is regarded as the gold stan-dard for RCR although arthroscopic surgery also bothprovides excellent results for patients in need of rotatorcuff repair (RCR). Arthroscopic RCR is less invasive butis thought to require a longer operative time and to resultin less secure repairs more prone to re-tear. We performedan outcomes study of 400 patients repaired by a singlesurgeon – 200 with open RCR or 200 with arthroscopicRCR – to test the hypothesis that open RCR providessuperior outcomes to arthroscopic RCR. Methods: For thisstudy, patients attended clinic pre-operatively and on fourpost-operative occasions, completing a pain and functionquestionnaire and receiving a systematic shoulder assess-