What Are Facet Joints? - Anatomy
Our spines are made up of a number of bones stacked on top of each other called the vertebrae, and these are linked together by ligaments and muscles. The moveable parts of the spine can be split in to three areas, the base (lumbar) containing 5 vertebra, the middle (thoracic) with 12 vetebra and the neck (cervical) with 7.
Each vertebra throughout the whole spine is joined above and below by a pair of small weight bearing joints called the facet joints and these are designed to allow, but control movement. The joint surfaces have a fine cartilagenous lining tissue to help with cushioning and provide protection to the joint surface. The size and shape of the individual vertebrae significantly changes from being much larger at the bottom to smaller at the top. This is a consequence of, and indeed a reflection of the larger forces that are subjected to the vertebrae throughout the lower back. Despite this, there is actually a lower porportion of pain attributed to the facet joints in low back pain than in neck pain, and this is thought to be due to the variations in available movement at the verterba, and also the angle of the joint.
Why Do They Get Sore?
Like any other joint in the body, facet joints have the potential to become sore and this is represented below. This could be through trauma, congenital (born with it) or degenerative abnormalities. The normal presentation is of a generalised aching over the lower back area that is maybe a little more tender locally around the joint site. The pain may be quite sharp if pressed. The achy feeling can often travel into the buttucks or even the upper leg in some cases. The reason for this travel is generally accepted as neurological. In these cases however it is important to point out that the nerve is not normally being compressed and so the risk of long term damage is not significant if dealt with appropriately.
Pain is quite simpy an intepretation by the brain of signals being sent to it by the nervous system. Most of you will have experienced different types of pain in the past and we are not only talking about the intensity, but was is sharp, did it shoot or was it a deep ache? It won’t then come as to much of a surprise to know that we have different types of nerve endings that convey different types of message. In the case of the facet related pain we normally get two different types, the generalised toothache around the back and sometimes buttock, and the short sharp ‘ouch’ pain.
When we recieve a soft tissue injury our body reacts in an attempt to fix it, in this case, a facet joint injury. Part of this regeneration involves the delivery of a chemical soup commonly known as inflammation which, in simple terms, delivers ‘fixing‘ agents to the area of damage but also helps to reabsorb any damaged tissue. Unfortunately, one type of nerve ending, the chemoreceptor is excited by the presence of some of these chemicals and fires lots of impules that eventually reach our brain. These slow travelling impulses are responsible for the widespread, deep toothachy feeling. If however we were to move in a certain direction that consequently ‘irritates’ the facet joint, you will often get a short sharp pain. This is a much faster signal from a different receptor whose primary aim is to prevent further damage. The best way to stop you in your tracks is by pain which most will agree is an effective method!!
Most facet joint irritations are self limiting and react well to simple conservative management such as medication, education and or exercise. Information on basic exercises can be found Here. In those cases where pain persits you may need further dianostic tests such as MRI scans or Facet Joint Injections, but this is best done under the guidance of your consultant. The injections are not curative but diagnostic, although they can provide temporary relief acting subsequently as an ’enabler’ for conservative interventions such as physiotherapy. The most important aspect in the management of LBP is differetiating between those problems that have the potential for serious harm, and those that are likely to settle. Thankfully, the latter is the majority group however you should always consult your Medical Practitioner or Therapist if you are unsure.
The following are links to some alternatve sites that offer useful information regarding facet joint inflammation.
