Effects of Blackburn Exercises on Scapulothoracic Stability in Patients With Type-1 Scapular Dyskinesia

The shoulder joint plays an important role in the function of the upper limb and in the activities of daily living. Shoulder pathologies are very common with the lifetime risk being between 40% and 60%. Prevalence rates of shoulder disorders are approximately 70% as compared to other musculoskeletal conditions. Ideal motion of scapula plays a major role in the shoulder functioning, any variation in the kinematics of scapula leads to various pathologies in shoulder and alteration in the scapular positioning can affect pain in the shoulder. Loss in the rhythmic functionality of the scapula due to muscular imbalance results in the scapular dyskinesia.

Scapular Dyskinesia is an observable alteration in the position of the scapula and the pattern of scapular motion in relation to the thoracic cage during static or dynamic movement of scapula. According to Borloz et al., a defective scapular posture caused by muscular imbalances, also generates imbalances of muscular strength. Scapular dyskinesia is followed by combination of symptoms such as malposition of scapula, prominent inferior border, pain in coracoids process and scapular motion dyskinesia. Patients report scapular medial border pain mainly. Kibler et al classified scapular dyskinesia in three dysfunctional patterns. Type I is characterized by posterior displacement or winging of the inferior medial scapular border. It is associated with inflexibility of pectoralis major and minor, and weakness of lower trapezius and serratus anterior. Type II is characterized by the projection of the entire medial border of the scapula. Type III is characterized by excessive superior translation, with elevation and some anterior displacement of the superior border of the scapula on the thorax. According to data reported in the literature, Scapular Dyskinesia (SD) incidence is frequent in patients with shoulder diseases, including rotator cuff diseases, glenohumeral instability, impingement syndrome, and labral tears. Type 1 pattern is however most commonly found in patients with rotator cuff dysfunction , shoulder impingement and instability, with the development of dyskinesis being associated with trapezius and serratus anterior, both of which are weakened in Type 1 Scapular Dyskinesia.

Generally the muscles that stabilize the scapula are directly related to direct-trauma, microtrauma, leading to muscle weakness and inhibition of movement by painful conditions around the shoulder. The serratus anterior and trapezius are the most susceptible to the effects of this inhibition, and are most often involved in the early stages of shoulder pathology. Stability at the scapulothoracic joint depends on the surrounding musculature. When the arm is raised overhead, the scapulothoracic motion involves upward rotation and posterior tilt of the scapula. Of the numerous muscles inserted on the scapula, those playing the most important role in the scapulothoracic kinematics are the upper and lower trapezius, and the serratus anterior. The serratus anterior (SA) works in concert with the upper and lower trapezius to upwardly rotate the scapula. Most overhead lifts and push-ups effectively recruit the serratus anterior. Activity of the serratus anterior tends to increase linearly with the amount of elevation at the glenohumeral joint. So when the scapulothoracic rhythm is altered, there are associated changes in glenohumeral angulation and loss of normal arm position, motion and stability.

In rehabilitation of scapular dyskinesia, therapeutic exercises should give attention to restoring the alignment of the scapulothoracic area and control of scapular muscles. The physiotherapy management is aimed to decrease the imbalances in the scapular stabilizing muscles so that control of scapular motion can be acquired. Interventions for scapular dyskinesia comprise of various stabilization exercises for scapula, but evidence scarcity is there in relation to Blackburn exercises in scapular dyskinesia. Blackburn exercises are one of the ways to treat shoulder pain and to regain proper mobility and decrease painful movements. These scapular stabilization exercises, based on stretching and strengthening, aim to improve muscle strength and joint position sense. The goal of increasing muscle strength is obtained with the aid of facilitation, and focus on restoring the alignment of the scapulothoracic area and control of scapular muscles. The Blackburn exercises are optimal for the stimulation of lower trapezius, being the "Y" the optimal exercise for this purpose. However, there is no clear evidence regarding their effect on serratus anterior. Although serratus anterior muscle works in concert with lower trapezius, and it is the only scapulothoracic muscle that produces upward rotation of the scapula with acromioclavicular (AC) joint external rotation and posterior tilting.

There is dearth in literature regarding the effect of Blackburn exercises on scapulothoracic stability in Dyskinesia, in relation to serratus anterior and lower trapezius muscles. There is poor available evidence regarding the effects of Blackburn exercises specifically on serratus anterior muscle strength, contributing to scapulothoracic stability. Also, the studies conducted previously were lacking a control group for comparison, and majority of the intervention protocols evaluated the immediate effects of Blackburn exercises with no focus on scapular stabilizers.