Shoulder Impingement how, why and what we can do
Shoulder pain and shoulder injuries are extremely common subacromial pain syndrome however for the purpose of this blog we will refer to as impingement is the most common injury you will find in the shoulder. If you are male and over 50 there is an extremely high chance you will experience impingement.
There are three types of impingement:
Primary Impingement - will occur when the as a direct compression of the rotator cuff tendons between the humeral head and the overlying anterior third of the acromion, coracoacromial ligament, coracoid or acromial clavicular joint. These structures are shown in the image below.
Secondary Impingement - Impingement can be secondary due to underlying glenohumeral joint instability, this will occur due to damage of the capsular ligaments or the labrum from excessive demand. This is very common in throwing sports. Due to increased humeral head translation the bicep and rotator cuff tendons become impinged. Progressively this impingement can lead to fatigue tears in the rotator cuff.
Internal Impingement - Usually found in the younger more athletic shoulder. When the shoulder is placed into 90 degrees of abduction and external rotation this causes the infraspinatus and supraspinatus tendons to rotate posteriorly, which can lead them to align and rub on the supra glenoid rim. Over head sport or overhead occupations should be a risk factor for this.
Scapular kinematics which means normal movement of the scapular are essential to shoulder mobility and research has showed that scapular dyskinesis (abnormal movement) is generally characterised by a lack of upward rotation, a lack of posterior tilting and increased internal or medial rotation of the scapula. This finding is widely acknowledged to be a factor in impingement and is commonly found in patients with shoulder pathology. In addition soft tissue inflexibility, tightness of the pectoralis minor and posterior glenohumeral capsular stiffness have also been highlighted in relation to abnormal scapular position.
Research into rotor cuff strength suggests that muscular balance is the most important factor and that muscular imbalance can lead to pathology. The primary objectives of these strengthening programmes are to create high levels of rotator cuff and scapular activation using movement patterns and positions that do not create significant subacromial contact, or undue stress to the static stabilisers of the glenohumeral joint. An example of these exercises are side lying external rotation and prone shoulder extension with an externally rotated position are typically utilised first used and exercises are then progressed.