Acromioclavicular joint arthritis
The acromion of the scapula is the projection over the top of the shoulder under which the rotator cuff (RC) passes. The acromion makes a joint with the outer end of the collar bone (the clavicle). This is the acromioclavicular joint (ACJ).
Almost all men and many women over 60 years of age develop swelling, mild deformity, and roughness of the ACJ: this is arthritis (dePalma, 1972).
Arthritis is readily seen on simple X-rays of the ACJ. Arthritis can also occur after injury of the joint, for instance after contact sports or after falling on to the point of the shoulder from a bicycle. Like an iceberg has the majority of its bulk under the surface of the water, so the arthritic ACJ may have the majority of its swelling on its undersurface in the form of a spiky swelling. This can act as a razor, causing fraying and damage to the upper surface of the RC tendons as they pass underneath the ACJ.
The shoulder has the pain of the impingement, the pain of the damaged RC, and now also the pain of the arthritic ACJ (which is often sore to lie on, or painful when the arm is stretched across the body, causing specific pain over the swollen joint).
Luckily the arthritis pain of the ACJ often comes and goes (as the fluid swelling inside the joint recollects and absorbed respectively), and, as long as it is not causing progressive damage to the RC beneath, arthritis of the ACJ can be managed without an operation. We look for progressive RC damage using the USS.
Shape of the collar bone (clavicle)
One aspect of the research undertaken by Mr Lambert involves looking at the shape of the clavicle (the collar bone) and in particular, how it twists. Working with colleagues from the AO Foundation, this knowledge is used to design new implants to fix clavicle fractures and assess how the shoulder girdle works. (Image: Mr Simon Lambert)