Acromioclavicular Joint dysfunctions
Updated: Feb 27, 2019
Hi guys, in today’s blog we will be discussing acromioclavicular joint dysfunctions, what they are and how they occur.
The acromioclavicular (A/C) joint is located on the top of the shoulder and is the bony bump where the acromion of the scapula (shoulder blade) connects to the distal end of the clavicle (collar bone).
There can be a number of reasons why A/C joint dysfunctions occur, with the most common we see in the clinic being trauma or repetitive overuse through the area.
The A/C joint is primarily comprised of two bones that join together with a cartilaginous disc, suspended from the joint capsule, between them. It is held together by 3 main ligaments;
1. The acromioclavicular (AC) ligament
2. The conoid Ligament
3. The trapezoid ligament
When grouped together the conoid and trapezoid ligaments are known as the coracoclavicular (CC) ligament.
The purpose of these ligaments is to provide stability to the joint and thereby prevent separation or excessive movement of the two bones involved.
An overuse A/C joint injury occurs over time as repeated, excessive stress is placed through the joint. Cartilage at the ends of the acromion and clavicle bones protects the joint from daily wear and tear. Over time, the demand placed on this cartilage may be more than it is capable of enduring, resulting in an overuse injury and significant wearing of the cartilage, resulting in arthritic changes to the joint surfaces.
These injuries are most common in individuals who perform tasks, such as heavy weight lifting (bench and military presses), or jobs that require physical labour with the arms stretched above the head.
A traumatic A/C joint injury occurs when there is a disruption to the joint capsule and damage to the ligaments holding the 2 ends of the bones together. This injury is called a shoulder separation as opposed to a shoulder dislocation which involves the ball and socket joint of the shoulder.
Traumatic injuries are most common in people who fall either directly onto the point of the shoulder or onto an outstretched hand (i.e. in an attempt to break fall) or when a force is applied in a downward direction onto the top of the shoulder (i.e. getting tackled or applying a tackle). These injuries are classified by the amount of damage to the ligaments, how much separation is occurring between the two bones, and the position of the clavicle post injury.
They are graded as follows:
Grade 1 - Involves a mild sprain to the AC ligament, no damage to the CC ligament and the clavicle remains in line with the acromion.
Grade 2 - Involves complete rupture of the AC ligament and joint capsule, sprain to the CC ligament and the clavicle is raised above the level of the acromion.
Grade 3 - Involves complete rupture of the joint capsule, AC and CC ligaments. Clavicle is elevated up to 25mm.
Grade 4 - Involves complete rupture of the joint capsule, AC and CC ligaments. Clavicle is displaced behind the trapezius muscle
Grade 5 - Involves complete rupture of the joint capsule, AC and CC ligaments. Clavicle is elevated up greater than 25mm.
Grade 6 - Involves complete rupture of the joint capsule, AC and CC ligaments. Clavicle is displaced inferiorly. This is rare and generally considered a medical emergency.
Patients with A/C joint disorders commonly present with generalised shoulder pain and discomfort, especially over the point of the shoulder. There may be a visible bump on top of the shoulder, loss of movement and strength at the shoulder joint and pain when lying on the affected side, lifting overhead or particularly when moving the arm across the body.
A/C joint dysfunctions can be very uncomfortable and can take time heal, even for grade 1 and 2 type injuries. The reason being is that the A/C joint is essentially a bony joint without a lot of surrounding muscular support. Once damaged the entire weight of the arm causes a distraction effect on the damaged joint capsule and ligaments which causes pain and increases the healing time.
The first step in treating these conditions is to unload the A/C joint so the joint structures can heal. This can be done by placing the arm in a sling or, in order to maintain some function in the arm, by taping the clavicle down and the arm into an elevated position. During this time, we also want to work on restoring range of movement by reducing swelling and inflammation with modalities such as ice or heat, massage, stretching and mobilisation to the surrounding muscles and joints. It’s important to beware that even after all symptoms have resolved there may still be a bony ‘step deformity’ through the A/C joint.
Once the joint structures have healed and the pain reduced our treatment plan focuses on restoring strength to shoulder by following a progressive, weights based, exercise program. Your chiro or physio will prescribe you with an exercise program that is designed to increase strength in the shoulder, back, chest and arms which allow for normal co-ordinated upper limb movement. In patients who are presenting with overuse type injuries, we will also address the underlying cause of the injury to help minimise the risk of recurrence.
Traumatic injuries such as falls are hard to predict and prevent, however overuse injuries can be.
Some quick tips to reduce the likelihood of suffering an A/C joint dysfunction in the future are:
Make sure you are lifting with good form and don’t push through pain.
Monitor work and weight-lifting activities, particularly repetitive overhead lifting and ensure there is good balance of back and chest exercises.
Maintain general shoulder strength and movement to safely perform desired tasks.
Seek help earlier rather than later.
If you feel repetitive discomfort through the A/C joint when lifting, have it seen to as quickly as able.
So that’s a brief overview of how A/C Joint disorders can occur, If you have questions or comments feel free to e-mail us at firstname.lastname@example.org and we will happily answer them for you.
If you think you may still be suffering from an A/C Joint disorder and want relief now, then call us on (08) 9486 8653 and we will arrange an appointment for you.