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Kinematic and muscle activity characteristics of multidirectional shoulder joint instability during elevation

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.

Electromyographic analysis in patients with multidirectional shoulder instability during pull, forward punch, elevation and overhead throw

Multidirectional shoulder joint instability alters the role of dynamic stabilizers, as a result of which the motion patterns of the muscle around the shoulder joint are also changed. The aim of this study was to compare the muscle activity of patients with multidirectional shoulder instability and the control group during pull, forward punch, elevation and overhead throw. Fifteen subjects with multidirectional shoulder instability and fifteen control subjects with normal, healthy shoulders participated in the study. Both shoulders were tested in all subjects. Signals were recorded by surface EMG from eight different muscles during pull, forward punch, elevation and overhead throw. The mean and standard deviation of MVE% for the different movement types and time broadness values during overhead throw were determined for each muscle in both groups and compared with each other. Test results suggest that in case of patients with multidirectional shoulder instability the various motions are performed in a different way. The results give rise to the assumption that the centralization of the glenohumeral joint and the reduction of instability are attempted to be ensured by the organism through increasing the role of rotator cuff muscles and decreasing the role of the deltoid, biceps brachii and pectoralis maior muscles. The analysis of time broadness shows that in patients with multidirectional shoulder instability, the time difference between the peaks of normalized voluntary electrical activity is significantly greater than in the control group.

Electromyographic analysis during pull, forward punch, elevation and overhead throw after conservative treatment or capsular shift at patient with multidirectional shoulder joint instability

PURPOSE The aim of this study was to compare the muscle activity of patients with multidirectional instability treated in a conservative or complex manner (capsular shift with postoperative rehabilitation) and the muscle activity of stable shoulder joints before and after treatment during pull, push, and elevation of upper extremities and during overhead throw. SCOPE The study was carried out on 34 patients with multidirectional shoulder instability treated non-operatively, on 31 patients with multidirectional shoulder instability treated operatively, and on 50 healthy subjects. Signals were recorded by surface EMG from eight different muscles. The mean and standard deviation of the maximum amplitude of normalized voluntary electrical activity for the different movement types and time broadness values during overhead throw were determined for each muscle in all groups and compared with each other. CONCLUSION The centralization of the glenohumeral joint and the reduction of instability is attempted to be ensured by the organism through increasing the role of rotator cuff muscles (p=0.009) and decreasing the role of the deltoid, biceps brachii, and pectoralis maior muscles (p=0.007). At patients after short-term and long-term conservative treatment, the maximum amplitude of normalized voluntary electrical activity of stabilizer muscles is significantly higher (p=0.006), and that of accelerator muscles is significantly lower (p=0.005) and the time broadness is significantly longer (p=0.01) than that of the control group. At patients after complex treatment (open capsular shift with postoperative conservative rehabilitation) the characteristic of the muscle pattern is similar (p=0.19) to the control group. The complex treatment resolves the labral ligamentous abnormalities by operative treatment and restores the impaired muscular control by postoperative rehabilitation, whereas the conservative treatment restores only the muscular control.

Comparison of gait parameters in patients following total hip arthroplasty with a direct-lateral or antero-lateral surgical approach

Total hip arthroplasty is a surgical procedure that usually results in almost complete pain relief and early improvement in functional capacity. Previous analyses of the gait of total hip arthroplasty patients have ignored the effect of total hip arthroplasty on the motion of other joints in the operated and non-operated limbs and of the pelvis. We investigated the spatiotemporal, angular, and kinetic parameters of affected and non-affected limbs pre-operatively and after three, six, and twelve months in 40 patients who underwent total hip arthroplasty via a direct-lateral approach, 40 patients who underwent an antero-lateral approach, and 40 age-matched healthy controls. In both patient groups pre-operatively, significant differences were observed in the spatiotemporal, angular, and kinetic parameters comparing the affected and the non-affected side; affected hip motion decreased, which was compensated by increased knee and hip motion of the non-affected side as well as pelvis obliquity and flexion-extension compared to healthy controls. Twelve months after total hip arthroplasty, direct-lateral patients displayed limited hip motion and increased pelvis rotation, while all antero-lateral patients exhibited gait patterns that most resembled the control group. This investigation has therefore identified a better functional outcome following an antero-lateral approach to total hip arthroplasty.

Physiotherapy vs. capsular shift and physiotherapy in multidirectional shoulder joint instability

PURPOSE The aim of the study was to compare the kinematic parameters and the on-off pattern of the muscles of patients with multidirectional instability (MDI) treated by physiotherapy or by capsular shift and postoperative physiotherapy before and after treatment during elevation in the scapular plane. SCOPE The study was carried out on 32 patients with MDI of the shoulder treated with physiotherapy, 19 patients with MDI of the shoulder treated by capsular shift and postoperative physiotherapy, and 25 healthy subjects. The motion of skeletal elements was modeled by the range of humeral elevation, scapulothoracic angle and glenohumeral angle, scapulothoracic (ST) and glenohumeral (GH) rhythms, and relative displacement between the rotation centers of the humerus and scapula. The muscle pattern was modeled by the on-off pattern of muscles around the shoulder, which summarizes the activity duration of the investigated muscles. RESULTS The different ST and GH rhythms and the increased relative displacement between the rotation centers of the scapula and the humerus were observed in MDI patients. The physiotherapy strengthened the rotator cuff, biceps brachii, triceps brachii, deltoid muscles, and increase the neuromuscular control of the shoulder joints. Capsular shift and physiotherapy enabled bilinear ST and GH rhythms and the normal relative displacement between the rotation centers of the scapula and humerus to be restored. After surgery and physiotherapy, the duration of muscular activity was almost normal. CONCLUSION The significant alteration in shoulder kinematics observed in MDI patients cannot be restored by physiotherapy only. After the capsular shift and postoperative physiotherapy angulation at 60 degrees of ST and GH rhythms, the relative displacement between the rotation centers of the scapula and humerus and the duration of muscular activity were restored.

Impact of the method of exposure in total hip arthroplasty on the variability of gait in the first 6 months of the postoperative period

INTRODUCTION, OBJECTIVE Gait analysis has provided important information about the variability of gait for patients prior to and after total hip arthroplasty (THA). The objective of this research was to clarify how the method of exposure in total hip arthroplasty affects the variability of gait. MATERIALS AND METHOD Gait analysis was performed at 0.8m/s, 1.0m/s, and 1.2m/s on 25 patients with direct-lateral exposure (DL), 22 with antero-lateral exposure (AL) and 25 with posterior exposure (P) during total hip arthroplasty. The control group was represented by 45 healthy subjects of identical age. Gait analysis was performed pre-operatively and 3 and 6months after the surgery. Gait parameter variability was characterized by the coefficient of variance (CV) of spatial-temporal parameters and by the mean coefficient of variance (MeanCV) of angular parameters. RESULTS The variability of gait tends to reach control values during the first 6months of the postoperative period in all three patient groups. Six months after THA, in patients operated with DL and AL exposure the variability of gait differs significantly from control values; however, in patients operated with P exposure, the variability of spatial-temporal and angular parameters - except the rotation of pelvis - was similar to that of controls. DISCUSSION, CONCLUSION The type of surgical technique significantly influences the variability of gait. Difference in the variability of angular parameters predicts gait instability and increased risk of falling after THA without the joint capsule preserved. Joint capsule preservation ensures a recovery of gait variability. It should be taken into account when compiling rehabilitation protocols. Differences related to the method of exposure should be considered when abandoning therapeutic aids.

Intermediate biomechanical analysis of the effect of physiotherapy only compared with capsular shift and physiotherapy in multidirectional shoulder instability

HYPOTHESIS This study compared the kinematic parameters and activity pattern of muscles around the glenohumeral joint in multidirectional instability (MDI) treated by only physiotherapy and by capsular shift and physiotherapy, before and after treatment, to test the hypothesis that the surgery group would demonstrate better kinematic and muscle activity than the physiotherapy group. MATERIALS AND METHODS The study comprised 32 patients with MDI treated with only physiotherapy, 19 patients with MDI treated by capsular shift and physiotherapy, and 50 healthy shoulders as the control group. The investigated kinematic parameters were the range of humeral elevation in the scapular plane, the scapulothoracic and glenohumeral angle, the scapulothoracic and glenohumeral rhythms, and relative displacement between the rotational centers of the humerus and the scapula. The muscle activity was modeled by the on-off pattern of muscles around the shoulder. RESULTS Before treatment, increased relative displacement between the rotational centers of the scapula and the humerus and different regression lines were observed in MDI patients. The physiotherapy strengthened the muscles, but regression lines remained monolinear. Capsular shift and physiotherapy resulted in bilinear regression lines and normal relative displacement between the rotation center of scapula and humerus was restored. After surgery and physiotherapy the activity pattern of muscles was almost normal. CONCLUSION The significant alterations in kinematic parameters in MDI patients cannot be completely normalized by physiotherapy only. After the capsular shift and postoperative physiotherapy, the bilinear regression lines (angulation at 60 degrees ), the normal relative displacement between the rotational centers of scapula and humerus, and the normal muscular activity pattern were restored to normal ranges and maintained for at least 4 years.