Alterations in Shoulder Kinematics and Associated Activity in People with Symptoms of Shoulder Impingement
Program in Physical Therapy, Department of Physical Medicine and Rehabilitation, Box 388 Mayo, 420 Delaware St, University of Minnesota, Minneapolis, MN 55455, USA. . Physical Therapy
(Impact Factor: 2.53).
Treatment of patients with impingement symptoms commonly includes exercises intended to restore "normal" movement patterns. Evidence that indicates the existence of abnormal patterns in people with shoulder pain is limited. The purpose of this investigation was to analyze glenohumeral and scapulothoracic kinematics and associated scapulothoracic muscle activity in a group of subjects with symptoms of shoulder impingement relative to a group of subjects without symptoms of shoulder impingement matched for occupational exposure to overhead work.
Fifty-two subjects were recruited from a population of construction workers with routine exposure to overhead work.
Surface electromyographic data were collected from the upper and lower parts of the trapezius muscle and from the serratus anterior muscle. Electromagnetic sensors simultaneously tracked 3-dimensional motion of the trunk, scapula, and humerus during humeral elevation in the scapular plane in 3 handheld load conditions: (1) no load, (2) 2. 3-kg load, and (3) 4.6-kg load. An analysis of variance model was used to test for group and load effects for 3 phases of motion (31(-60(, 61(-90(, and 91(-120().
Relative to the group without impingement, the group with impingement showed decreased scapular upward rotation at the end of the first of the 3 phases of interest, increased anterior tipping at the end of the third phase of interest, and increased scapular medial rotation under the load conditions. At the same time, upper and lower trapezius muscle electromyographic activity increased in the group with impingement as compared with the group without impingement in the final 2 phases, although the upper trapezius muscle changes were apparent only during the 4.6-kg load condition. The serratus anterior muscle demonstrated decreased activity in the group with impingement across all loads and phases.
Scapular tipping (rotation about a medial to lateral axis) and serratus anterior muscle function are important to consider in the rehabilitation of patients with symptoms of shoulder impingement related to occupational exposure to overhead work. [Ludewig PM, Cook TM. Alterations in shoulder kinematics and associated muscle activity in people with symptoms of shoulder impingement.
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- "The scapulohumeral rhythm is calculated as a ratio, essentially dividing the glenohumeral elevation or abduction angle by the scapulothoracic angle (amount of upward scapula rotation). This ratio provides information about the scapula rotation, and may indicate muscle imbalance and be related to injury. Shoulder pain (or injury) was defined as an incident (or occurrence) that required altered training, or rest from training, for a week or more. "
- "Observation of shoulder motion before and after RC repair may partly elucidate the observed functional gain. Shoulder motion can be measured quantitatively with 6 df by a 3-dimensional (3D) electromagnetic system.1,9,10,12,16,19,31However, evaluations of preoperative and postoperative 3D shoulder motion in RC repair with an electromagnetic system have not been published so far. "
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Patients with a rotator cuff (RC) tear often exhibit scapular dyskinesia with increased scapular lateral rotation and decreased glenohumeral elevation with arm abduction. We hypothesized that in patients with an RC tear, scapular lateral rotation, and thus glenohumeral elevation, will be restored to normal after RC repair.
Shoulder kinematics were quantitatively analyzed in 26 patients with an electromagnetic tracking device (Flock of Birds) before and 1 year after RC repair in this observational case series. We focused on humeral range of motion and scapular kinematics during abduction. The asymptomatic contralateral shoulder was used as the control. Changes in scapular kinematics were associated with the gain in range of motion. Shoulder kinematics were analyzed using a linear mixed model.
Mean arm abduction and forward flexion improved after surgery by 20° (95% confidence interval [CI], 2.7°-36.5°; P = .025) and 13° (95% CI, 1.2°-36.5°; P = .044), respectively. Kinematic analyses showed decreases in mean scapular protraction (ie, internal rotation) and lateral rotation (ie, upward rotation) during abduction by 3° (95% CI, 0.0°-5.2°; P = .046) and 4° (95% CI, 1.6°-8.4°; P = .042), respectively. Glenohumeral elevation increased by 5° (95% CI, 0.6°-9.7°; P = .028) at 80°. Humeral range of motion increased when scapular lateral rotation decreased and posterior tilt increased.
Scapular kinematics normalize after RC repair toward a symmetrical scapular motion pattern as observed in the asymptomatic contralateral shoulder. The observed changes in scapular kinematics are associated with an increased overall range of motion and suggest restored function of shoulder muscles.
- "Fig. 7). If no further sensomotoric deficits are present, the secondary focus should be inrestoring muscle disbalances[6,7,25]. The upper trapezius (UT) muscle often shows hyperactivity in patients with SD, and thus exercises should be selected that activate the lower trapezius (LT) and the anterior serratus muscle (SA). "
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ABSTRACT: For a balanced scapulohumeral rhythm in arm elevation, it is necessary to have an optimal position, motion, stability and muscle performance of the scapula and scapular muscles. In the case of abnormal movements, so-called scapular dyskinesis, the tendons (e.g. biceps tendon, rotator cuff) can be irritated and may cause pain in overhead activity. There are various causes for scapular dyskinesis and, therefore, the treatment is a challenge for therapists. The aim of conservative treatment is to restore normal position and movement of the scapula and furthermore dynamic scapular stability during overhead activities. Rehabilitation based on effective exercises should be tailored individually and the complexity of the exercises should be increased slowly.
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