It is difficult to identify objective parameters for assessing the joint function when evaluating the outcome of orthopaedic procedures, especially endoprosthetic replacement. Spatial and temporal parameters of gait have clinical relevance in the assessment of motor pathologies, particularly in orthopaedics. However, the influence of gait speed on these biomechanical parameters has been difficult to be taken into consideration so far. The objective of the present study was to analyse the impact of gait speed on gait parameters and to set a standard walking speed for patients with osteoarthritis by means of a special treadmill control mechanism. The second objective is to compare the gait patterns in patients with unilateral osteoarthritis of the hip joint or of the knee joint to the gait pattern of healthy control subjects. A total of 20 patients with severe unilateral osteoarthritis of the hip, 20 patients with severe unilateral osteoarthritis of the knee and 20 healthy elderly subjects without any history of lower extremity joint pathology were investigated at four different gait speeds. The gait analysis equipment used consisted of an infinitely adjustable force-instrumented treadmill and an ultrasound-based motion analyser system with electromyography. Our data suggest that most of the biomechanical parameters depend on gait speed. The highest gait speed that all our patients with severe osteoarthritis were suitable with, without pain and loss of coordination, was 2.00 km/h. Our findings indicate that the changes in gait parameters may occur in patients with unilateral osteoarthritis of the hip joint or the knee joint compared to the gait pattern of healthy control subjects. Hip joint or knee joint degeneration was compensated for in part by the pelvis and other joints in the lower limb. Reduced motion of the hip joint or knee joint leads to an increased pelvic motion, which should affect the natural mobility of the lumbar spine and cause pain in the lumbar region of the spine because of their kinematic interaction.

Alterations of shoulder motion have been suggested to be associated with shoulder disorders. The objective of this study was to perform a 3D motion analysis (kinematic and electromyographical) of skeletal elements and muscles of shoulder joint in patients with multidirectional instability. Fifteen patients with multidirectional instability and 15 normal controls were investigated during continuous elevation in the scapular plane. The spatial coordinates of 16 anatomical points of the shoulder to determine kinematical parameters were quantified by an ultrasound-based motion analyzer. The activities of 12 muscles were measured by surface electromyography. Kinematic characteristics of motion were identified by scapulothoracic, glenohumeral, and humeral elevation angles; range of angles; scapulothoracic and glenohumeral rhythm; scapulothoracis, glenohumeral, and scapuloglenoid ratios; and the relative displacement between the rotation centers of the humerus and the scapula. The electromyographical characteristics of motion were modeled by the on-off pattern of muscle activity. Significant alterations in kinematical parameters were observed between patients and asymptomatic volunteers. The anterior, posterior, and inferior dislocations of shoulders with multidirectional instability could be properly modeled by the relative displacement between the rotation centers of the scapula and humerus. The shorter activity by m. pectoralis maior and all three parts of m. deltoideus and longer activity by m. supraspinatus, m. biceps brachii, and m. infraspinatus assure the centralization of the glenuhumeral head of a shoulder with multidirectional instability.

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