We all love a good anagram. They serve a rather wonderful shorthand purpose in writing and identifying items so that in a conversation, you can be precise and clear about what you are talking about without having to go to great lengths to say long winded latin words or phrases. In anatomy these are great shortcuts because if you constantly have to talk about every muscle or joint space, conversations become dextrous practice sessions at linguistics. However, with so many terms and shortened speak, for the non initiated these short capital letter laden terms can be slightly confusing and leave you unsure of exactly what term or area of the body you are actually talking about. It may resemble being a spectator to an episode of the manic minute on the Sale of the Century, where everyone is firing off answers and questions and you really have no idea what category or subject anyone seems to be talking about. I also wonder whether anatomists created these anagrams as a kind of secret language that they could partake in just to be clever. Like the clever kids at school who could have secret conversations with their Pig Latin!
In talking about shoulder dislocations, The Acromio-clavicular joint is one such anagram that suffers from being similar to another nominated structure with the same initials. The ACL usually stands for Anterior Cruciate Ligament found at the knee. However the Acromio Clavicular joint is referred to as the AC. This joint refers to the outermost (lateral) aspect of the shoulder where the clavicle meets the scapula. In other words, the bony bit on the tip of the shoulder. It’s a vastly important joint as it allows for the upward motion of the arm. A synovial joint in structure, it does actually resemble more of a pivot point in movement, acting as a strut allowing the humerus to rotate and move upwards. It acts directly on the scapula helping to move the shoulder articulation and thus allow the arm to move in a greater range of motion.
In looking at the shoulder girdle, the AcromioClavicular Joint is one of the two main and important joints. The other being the Glenohumeral Joint which is actually the connection between the arm and the torso. The humerus, the arm bone connects to the torso via the glenoid fossa which is part of the scapula. This joint is a loosely connected ball and socket joint that allows the arm to rotate and move in its multi-directional arc. It is very shallow which is why it has much more movement than other ball and socket joints in the body, namely the hip joint.
Shoulder Dislocation is the term that is often thrown around for any disruption to the shoulder area. However, technically this is not true as a dislocated shoulder refers more to the joint that is the glenohumeral joint. When the arm bone comes out of the fossa (socket) this is technically a shoulder dislocation.
Injury to the Acromio-Clavicular joint is slightly different and technically is termed a Separated Shoulder. It is usually the dislocation of this ‘strut’ that lies over the top of the actual ball and socket joint (glenohumeral) which is the shoulder articulation. The AC Joint is particularly indicated when you have a fall or impact to the area. And just to make more use of the anagram (or ‘I’m rather clever speak’) the term coined is FOOSH (Fall On OutStretched Hand).
As such, a separated Shoulder is a more common injury in sports such as martial arts, Rugby, Australian Rules and even skiing, mountain biking and skateboarding that can often involve bracing motions of this type with the arm being the contact point in a fall.
Any issue with the AC joint involves strain to the two important ligaments, the Acromioclavicular Ligament (not the ACL) and the Coracoacromial Ligament. Both these ligaments reinforce the AC articulation and both are at great risk of being injured with too much strain or stress falling on the structure itself. Tears on these ligaments weaken the joint itself and will make compromise the stability of the whole shoulder area. Without the AC being able to move, the scapula cannot move as well and thus any movement of the arm is compromised. It also has effects on stability of the shoulder, as the scapula being unable to be secured in place, makes the whole shoulder unable to bear a load, say in a push-up or ball throw.
Dislocations can vary in degree and these are ascertained by measuring the amount of dislocation of the joint space. Anything less than a 4-5mm gap in the articulation is usually associated with a lower Grade (1-3) diagnosis whereby larger differences and ruptures to the two ligaments denote higher grades (4-6) of dislocation. The higher graded dislocations take much longer than the 16-20 weeks of suggested recovery for Grade 1-3 dislocations and will often usually involve surgery to reattach the torn ligaments and alignment of the scapula.
Treating an AC injury involves gently regaining range of motion and ensuring that the fibres of the ligaments don’t create too much scar tissue. Whilst immobilisation is important in the early stages of recovery, you do want to encourage movement in all planes of motion as soon as possible to encourage free movement of fibres and articulations. This promotes a flexibility in the ligaments and tendons of muscles associated with shoulder movement. I often find myself encouraging clients who are even recovering from soft tissue damage in the shoulder to stress the shoulder joint. It responds to movement and needs to be used and stretched in its planes of action so that the structures involved once again become flexible and open. Of course, you do not want to overstress the joint, but working within the pain range and time frame of recovery is vital to full joint recovery in the long term.
You also want to pay close attention to the neck and the upper cervical spine. These areas are dependent on the alignment of the pectoral girdle, and a compromised AC joint influences the clavicle aligment, which has major repercussions on any muscle that attaches here. Namely the sternocleidomastoid, the scalenes, the levator scapulae. We should also address the alignment of muscles that descend from the clavicular articulation as well such as the pectoralis minor and biceps muscles. Working here and ensuring these areas are addressed with strengthening and stability work and ensuring length and health is very vital to complete recovery after a Separated Shoulder.
Without movement and healthy tissue repair directly in the ligaments of the AC, arthritis in the joint can become an issue later on. Also, movement may be compromised and this creates instability and reduced functionality in a joint that is largely used in all manner of movements and actions. Reinforcing the stabilisers of the shoulder joint and the associated muscles that act on the scapula, the clavicle and even the rib cage are very important to healthy and complete recovery. Increasing stability here will help issues from returning in the future and also in creating a better technique in function of the shoulder itself.