Shoulder pain with throwing, golf and tennis - and a bit about cavemen
We see a lot of people who tell me their shoulder pain began after throwing, some of these play cricket to a high level, some are athletes and some are just launching something for the dog to chase. The forces involved in racket sports and golf are very similar to throwing, and shoulder pain in this population is another common problem that I see. So if you are fed up missing out on your weekly tennis game, or can’t commit fully to your drive because of pain or the dog just looks at you wistfully every time you pass a stick then read on!
Ever since our early ancestors began to walk on two legs (around 4 million years ago) our shoulders and elbows began to evolve for the purpose of positioning our hand in space. Together, the shoulder and elbow allow us to manipulate our hand into just about any position. Walking on two legs (bipedal stance) freed up the rapidly evolving human hand for many tasks. Whether this be stone-age man crafting and using tools and harnessing fire to more modern problems like lying with your head and shoulders in a kitchen cupboard, negotiating a maze of obstacles to reach the water stopcock!
The shoulder is the most mobile joint in the body and this allowed us to reach up and forage food from trees. Previously, like with apes, this mobility had allowed us to swing from branches. But, with time, our shoulder blade evolved. This allowed us to exploit this mobility in a new and novel way. A way to harness our shoulders major strength, that which set us apart and put us firmly at the top of the food chain; our ability to throw with accuracy and speed. The pay off for this is that we are now less well suited to dangling and activity with our arms above our heads. As such there is a much higher prevalence of shoulder pain in manual workers and people who work above shoulder height like electricians and window cleaners.
Our shoulder is a ball and socket joint. The ball sits at the top of the arm bone (the Humerus) and is known as the ‘humeral head’. The socket (the glenoid) is part of the shoulder (scapula). The socket is small and the ball rests against it giving rise to the analogy of the shoulder being like a golf ball sitting on a golf tee. Ligaments normally bind bone to bone over a joint and help to stabilise it (hold the two parts together), the tighter the ligaments the less movement there is. In order to allow greater mobility in the shoulder the ligaments are lax; we sacrifice stability for mobility. As such the shoulder is the most commonly dislocated joint in the body