Patient: Male 35 Years of Age
I recently had a patient come see me in regards to shoulder pain. While bench pressing the patient felt a pull in his left shoulder. Not knowing what it was, he stopped exercising and took a break. He is in his mid 30’s and physically active. X-ray and Ultrasound came back unremarkable. No swelling in the shoulder. Only pain when reaching overhead and when bringing his arm across his body (adduction movement). What is happening, he asked? What would cause this type of shoulder pain, decreased motion and weakness.
Our shoulder region is made up of the arm bone (humerus), shoulder blade (scapula), and collarbone (clavicle) – see images below. The humerus attaches into the scapula. Furthermore, the scapula has a protruding bony area at the top of the arm bone called the acromion. The acromion attaches to the collarbone or clavicle. This joint or connection is known as the acromioclavicular joint (AC Joint). The AC joint is held together by various ligaments. Ligaments are soft tissues which connect bone to bone. The ligament between the acromion and clavicle is called the acromioclavicular ligament. Furthermore, you have two other ligaments which hold the clavicle down on the scapula. These are known as the coracoid-acromion ligament and coraco-clavicular ligament. Surrounding the bones and ligaments are muscles. The rotator cuff muscles are responsible for most movements in the shoulder. They help us to raise our arm over head, comb our hair and open a door.
What is the purpose of the AC Joint? The AC joint allows the ability to raise the arm above the head. This joint functions as a pivot point, acting to help with movement of the scapula resulting in a greater degree of arm movement.
How do the ligaments surrounding the shoulder sprain or tear?
The ligaments of the shoulder sprain or tear most commonly is one falls on an outstretched arm, falls on their shoulder or endures a sport injury (football, weightlifting, rugby, etc.).
How are AC Joints Graded?
AC joint separations are graded from mild to severe. The grading depends on which ligaments are sprained or torn. The mild type, grade 1, is a simple sprain of the AC ligaments. A grade two AC separation involves a tearing of the AC ligaments and a sprain of the coracoclavicular ligaments. A complete tear of the AC ligaments and the coracoclavicular ligaments is a grade three AC separation. This injury results in the bump on the shoulder which is known as a step defect.
Let us recap the grading of an AC joint injury:
- Grade 1 is a simple sprain to the AC joint
- Grade 2 involves rupture of the AC ligament
- Grade 3 rupture of both AC and CC ligaments which often results in a superior displacement.
- Grade 4 involves posterior displacement (movement backwards)
- Grade 5 superior (upwards) displacement, to a greater degree than grade 3, with an increase in coracoclavicular space by 3-5 times normal
- Grade 6 involves full rupture of both AC and CC ligaments with the clavicle being displaced downwards.
How do I treat an AC joint dislocation?
Ice, graston therapy, soft tissue therapy, taping techniques, exercises/rehabilitation as well as laser therapy helps to heal the A/C joint area. Grades 4-6 may require surgical intervention. If this injury is neglected and allowed to heal out of place this could increase the wear and tear on your joint causing you problems in the future. Make sure you seek medical attention, if you experience this injury.
What else can this injury be?
It is important to rule out other conditions, such as SLAP lesions (labrum injuries), shoulder impingement, tendonosis and/or tears.
MEDICAL DISCLAIMER: The following information is my personal notes about this subject matter. It is intended for informational purposes only. Consult a health practitioner to help you diagnose and treat injuries of any kind.