The purpose of this study was to characterize glenohumeral joint laxity and stiffness using instrumented arthrometry. To evaluate the validity of an instrumented measurement system we compared cutaneous and bone-pinned measures of laxity and stiffness that replicate previously reported in vivo methodology. Characterization of capsular laxity was achieved through determination of the sagittal plane translational area at increasing levels of quantified force. Finally, a method for increasing the objectivity of the standard manual laxity examination was developed for the orthopaedic clinician to quantify humeral head translation and capsular volume in vivo. We hypothesized that: 1) cutaneous measures could accurately predict bone-pinned measures, 2) capsular laxity would increase with increasing levels of applied force, and 3) manual cutaneous, manual bone-pinned, and force-displacement bone-pinned measures of translation would be equal. Thirty fresh frozen cadaveric shoulder specimens (mean age=70��14 years) were tested. The shoulders were thawed and mounted to a custom-made shoulder-testing apparatus. Displacement was measured using an electromagnetic tracking system. Sensors were secured cutaneously and with bone-pins to the scapula and humerus. Force-displacement testing was performed using a load applicator and manual displacement testing utilized the anterior/posterior drawer and inferior sulcus tests. A comparison of cutaneous and bone-pinned measures of laxity and stiffness revealed good to excellent criterion validity (r=0.68 to 0.79). Examination of displacement measures at increasing levels of force revealed increasing capsular laxity with symmetric directional compliance. No significant difference was observed between anterior and posterior translation (0.4 mm, p=.55), with significant differences between inferior and anterior (4.6 mm, p<.0001) and between inferior and posterior (5.1 mm, p<.0001). A comparison of manual cutaneous to bone-pinned manual and kinetic measures of translation revealed a significant difference between methods (p=.0024) and between directions (p<.0001) with no significant interaction (p=.0948). Estimations of the force required to achieve clinical end-point suggest that greater force is required in the anterior (173 N) direction compared to posterior (123 N) and inferior (121 N). We have developed two new methods to measure glenohumeral joint kinematics and reported new information regarding normal kinematics of the glenohumeral joint. / Graduation date: 2001

Joint Position Sense (JPS) of the shoulder as determined by repeated repositioning tasks has been performed under different constrained testing conditions. The variability in the testing protocols for JPS testing of the gleno-humeral joint may incorporate different movement patterns, numbers of trials used to derived a specific JPS variable and range of motion. All of these aspects may play an important role in the assessment of G-H JPS testing. When using a new instrument for assessing JPS all of these issues need to be examined to document the optimal testing protocols for subsequent clinical assessments. By undertaking these studies future clinical trials may be more optimally assessed to determine if there are differences between dominant and non-dominant arms as well as the presence of JPS changes in performance associated with pathology and rehabilitation. This study used a 3-dimensional tracking system to examined gleno-humeral JPS using 2 open kinetic chain movement patterns. The 'conventional' 90 degree abducted, externally rotated movement was compared to the hypothetically more functional D2 movement pattern used in proprioceptive neuromuscular facilitatory techniques. These two patterns were tested at different ranges (low and high). Two cohorts (n=12, n=16) of normal healthy athletic males aged 17-35 years, performed matching tasks of both left and right arms. The second cohort (n=16) were assessed with and without strapping the gleno-humeral joint with sports tape. Accuracy (overall bias) and precision (variability) scores were determined for progressively greater numbers of trials. The findings of the study show that estimates of JPS accuracy and precision become more stable from data derived from 5 to 6 matching trials. There were no statistical differences between sides [95%CI ± 1.5cm]. The accuracy but not precision improved as subjects approximated the 'high' end of range in the 'conventional' or D2 pattern. Furthermore, no systematic differences were detected at different ranges of movement or movement patterns with or without the application of sports tape. These findings provide a guide to the number of trials that optimise the testing of the gleno-humeral joint and also suggest that in normal controls the magnitude of differences between sides and movement patterns is similar. These findings also iii indicate that sports tape applied to the shoulder may not significantly change the JPS performance in healthy, athletic males.

Function of the shoulder complex is highly dependent on the relationship between the scapula and the humerus. Etiologies for the disruption of the glenohumeral relationship include impaired or abnormal scapular function, motion, or position. The lateral scapular slide test (LSST) has been developed as a clinical tool to assess this phenomenon, also known as scapular dyskinesis. The primary purpose of this study was to determine the validity of the LSST by comparing the clinical measurements on the skin surface to the actual anatomical distance between the scapula and the spine as seen on radiographic images. The secondary purpose of this study was to determine the intra-rater and inter-rater reliability of the LSST. Nine subjects (18 shoulders) were assessed with the clinical LSST and radiographic images in three test positions (0��, 45��, and 90�� of glenohumeral abduction). Comparison of the clinical LSST measurements with the radiographs revealed the LSST to be valid (>0.80) in only the 0�� and 45�� test positions with respective Pearson correlation values of 0.91 and 0.98. Excellent (>0.75) intra-rater ICC (2,1) reliability (0.91-0.97) was found for all three test positions. Inter-rater ICC (2,1) reliability values were excellent for the 0�� (0.87) and 45�� (0.83) test positions, and fair to good for the 90�� position (0.71). This study demonstrated that the LSST is an accurate and consistent measure of scapular movement and position for the 0�� and 45�� test positions. Clinicians should exercise caution when interpreting measurements obtained at the 90�� test position because the validity and reliability values did not reach established standards. / Graduation date: 2002

The purpose of this study was to further investigate the relationship between patterns of shoulder movement and muscular response. Thirteen females were tested against maximal manual resistance in twelve different patterns, eight straight plane, and four diagonal. Five of the six subjects who met established kinematic criteria were used for electromyographic (EMG) analysis of the anterior deltoid (AD), the middle deltoid, the posteroir deltoid (PD), and the pectoralis major. No significant differences were found between number of muscles solicited or duration of muscular effort during the different movements. Maximal EMG was significantly higher for the AD in abduction and in flexion than in the other patterns, and for the PD in diagonal flexion with abduction and in transverse abduction.

[Truncated abstract] Normal and pathological upper limb movement assessments rely on the valid and reliable identification of the glenohumeral joint centre of rotation (GHJ). However, clarifying the most suitable techniques to identify and reference this location has proved a challenge, and performing a variety of methods that lack validation is commonplace. This may not only be erroneous, but also prevents the standardised collection of upper limb biomechanical information. The principle aim of this research was to clarify the accuracy and reliability of various methods of GHJ identification, including both predictive and functional techniques, as well as the error associated with referencing the GHJ location during dynamic movement trials. Predictive methods of GHJ identification rely on a generic relationship between the GHJ position and predetermined anatomical distances or locations. The ISB recommended predictive method was developed and validated using cadavers, and it appears that a number of convenient, yet to be validated methods are routinely performed in preference of this recommended technique. In the present study, magnetic resonance imaging (MRI) was utilised to validate, in vivo, the accuracy of various predictive approaches; the ISB recommended method and a representative sample of commonly used techniques. A new multiple linear regression model and simple 3D offset method, were developed from the MRI identified locations of the GHJ and the surface markers. The results indicated that the new multiple linear regression model (13 ±4.6) mm and simple 3D offset (12 ±4.6 mm) found an average GHJ location closer to the MRI determined location than any of the established predictive methods (14-50 mm), including the ISB recommended method (32 ±8.2 mm), and a recently publicised amended 2nd version (16 ±8.4 mm). ... For instance when the optimal algorithm (geometric sphere fit), marker set and movement trial were used in the functional approach, average in vivo accuracy errors of 27 ±8.6 mm were reported, around half the error reported by the most accurate and reliable predictive method (13 ±4.6 mm). A further investigation aimed to determine the most suitable location to reference the GHJ during dynamic motion analysis trials. The GHJ was referenced in a number of upper arm and acromion technical coordinate systems (TCSs) in a series of static MRIs. This permitted the error associated with each set of markers to be calculated in vivo. The results indicated that a combination of TCSs defined from two sets of markers; one placed on the acromial plateau and one located proximally on the upper arm, produced the most accurate results, recording an average of 18 ±4 mm of error following a large humeral elevation (up to 180°). Furthermore, a distal upper arm set of markers proved to be inappropriate for GHJ referencing, reporting average errors greater than 30 cm in two large humeral elevations. Therefore, following the identification of the GHJ, its 3D location should be referenced in the average of two TCSs determined from respective sets of markers placed on the acromion and proximal upper arm, during dynamic trials.