AC Joint pain - The "Other" Shoulder Pain

Anatomy

The Acromioclavicular (AC) joint is located at the lateral tip of the shoulder. The joint is formed by two bones, the clavicle (collarbone) and the acromion (a portion of the scapula/shoulder blade). In between the joint sits a fibrocartilage meniscal disc and the bones are connected by a number of ligaments, muscles and a joint capsule.

Role

The AC joint acts as a pivot point in the shoulder allowing the shoulder blade to rotate as the arm is lifted upwards. If it is dysfunctional it affects the control of your shoulder.

About

The AC joint is very commonly injured in contact sports that involve tackling like rugby or AFL. This is classified as a traumatic injury in which the ligaments can be torn and the capsule disrupted which results in the bone separating. However, you can also have AC joint pain from overloading the joint or degeneration of the fibrocartilage meniscus. It can also develop into a condition called osteolysis which is quite common in gym goers.

Differentiation from “bursitis” or impingement (common shoulder pain)

Shoulder bursitis/impingement is a very common condition in which the bursa and tendons in the shoulder get inflamed or overloaded. Often a cortisone injection is prescribed which can reduce the pain if the bursa is the main issue. However, if it is not the correct diagnosis then ongoing pain and disability can perpetuate. It is very important to get your shoulder assessed by a physiotherapist to differentiate between the two conditions so the right treatment plan can be selected. Please note that Impingement CAN occur as a result of AC joint pain or injury but is not the primary diagnosis.

Common presentation

·         Pain at the top or tip of the shoulder

·         Difficulty lying on the shoulder

·         Difficulty bringing the arm across the body

·         Pain with lifting an object above your head

·         Pain with gym activities like bench press

General advice

·         Try icing the area especially when it is painful

·         Rubbing voltaren gel on the area can help reduce pain, the joint is superficial enough for the gel to have some effect

·         Applying taping to pull the shoulder upwards can take the pressure off the joint and relieve discomfort

·         A structured rehab program is helpful in making the muscles around the joint stronger so there is less load on the area

·         A cortisone injection can be helpful if conservative treatment isn’t effective, as long as they inject the right spot

·         Most importantly, visit your highly trained physiotherapist for a thorough assessment and in-depth treatment plan