For a coordinated movement of the shoulder joint, there is a synchronized movement of scapula along with humerus. Thus we have two contributors to the Shoulder elevation.
- Humeral movement at glenohumeral joint
- Scapular movement at scapulothoracic joint
Scapulohumeral rhythm is the interplay between the scapula and the humerus during motion of the shoulder.
There is a definitive pattern of interaction of scapula and humerus when contributing to the motion of the shoulder.
The scapulohumeral rhythm can be defined as the ratio of the glenohumeral movement to the scapulothoracic movement during arm elevation.
Scapulohumeral rhythm is also called glenohumeral rhythm.(1)
During the abduction movement of the shoulder joint, 120 degrees of motion is carried out at the glenohumeral joint and 60° at the scapulothoracic joint.
Therefore the ratio of movement occurring at the glenohumeral joint to scapulothoracic joint is 2:1 and is known as the normal scapulohumeral rhythm.(2)
In other words, for every two degrees of movement of the humerus, the scapula moves one degree(3)
Scapulohumeral ratio is calculated by dividing the total amount of shoulder elevation by the scapular upward rotation.
Your Physical Therapist may use certain tests like the lateral scapular slide test or scapular dyskinesis test to confirm his assessment.
Contribution of scapula and humerus in shoulder elevation
The scapula on the thorax contributes to elevation (flexion and abduction) of the humerus by upwardly rotating the glenoid fossa 50° to 60° from its resting position.
Glenohumeral -joint alone contributes 90-120°.
The combination of scapular and humeral movement result in a maximum range of elevation of 150-180°.
Understanding Shoulder elevation with respect to Scapulohumeral rhythm
Initial 30 degrees of shoulder elevation – Setting Phase:
The movement is largely glenohumeral.
Scapulothoracic movement is small and inconsistent.
After Initial 30 degrees of shoulder elevation:
The glenohumeral and scapulothoracic joints move simultaneously.
Overall 2:1 ratio of glenohumeral to scapulothoracic movement.
Purpose of Scapulohumeral Rhythm
Preserves the length-tension relationships of the glenohumeral muscles
the muscles do not shorten as much as they would without the scapula’s upward rotation, so it helps to maintain the force through a substantial range of motion.
Prevents impingement between the humerus and the acromion by moving glenoid
What happens if the Scapulohumeral rhythm is altered?
Altered scapulohumeral rhythm affects the function of the glenohumeral joint and contributes shoulder impingement, rotator cuff pathology and shoulder instability.(1)
A disturbed scapulohumeral rhythm is mainly due to a dysfunction of the movement occurring at the scapulothoracic joint.
The signs and symptoms
1. Pain and tenderness around the scapula
2. Limited movement of the shoulder joint
3. Pain in the posterior and superior shoulder
4. Drooping or elevated shoulder compared to the other
5. Posterior tipping of the scapula(2)
Study of scapulohumeral rhythm forms an important part of the clinical examination of the shoulder.(1)
Physiotherapy techniques to restore the scapulohumeral rhythm includes:
Neuromuscular facilitation techniques
Manual therapy techniques(2)
Active and passive mobilizations
Coordination between muscles(1)
If the scapular position is altered this normal pattern of integrated movement is expected to be affected. For this reason, the scapulohumeral rhythm is assumed as a movement quality index of the shoulder complex in clinical practice.
Researchers have shown an association between abnormal scapular movement and shoulder pathologies such as impingement syndrome and glenohumeral instability, among others. Based on such evidence, rehabilitation programme and protocols were developed focusing and emphasizing on appropriate scapular motion and stability retraining(3).
At Valley Healing Hands, we provide the best Physical Therapy treatment for altered scapulohumeral rhythm. We provide a perfect atmosphere developed for our patients with a one on one ratio for the best quality of care needed for maximum outcomes and return to play. Our physical therapist are highly qualified and will plan an individualized treatment routine, customized to your specific needs. Our patients are highly satisfied with our services. You can learn about what they have to say about us here and get connected to us here. Our patients love us and you too will! We are determined to get you back in the game!!!