The pelvis is composed of several bones. These include the ilium, pubis and ischium which fuse together during puberty to form each side of the pelvis. There are also the sacrum and coccyx bones. There are three joints within the pelvis:
1. The Sacro-iliac Joint or SIJ – this is the articulation between the sacrum and the ilium
2. The Sacro-coccygeal joint-between the sacrum and the coccyx
The pelvis also has articulations with the hip bones via the acetabulum located in the ilium and the 5th Lumbar vertebra with the sacrum.
The pelvis has several functions which include:
1. Transfer of weight – it allows for weight bearing and transfer of weight between the lower appendicular skeleton and the upper axial skeleton especially when walking, also providing shock absorption to these movements.
2. Provides attachment of muscles and ligaments to provide stability and help with movement.
3. Protects organs contained within the pelvis such as the bladder and reproductive organs.
It is evident that the pelvis is a crucial component of being upright and enables us to move, with effective transfer of load between the spine and the lower extremities.
The Sacro-iliac Joint allows us to move, however it can be responsible for low back pain. Each joint only moves 2-4mm when we are walking, however increased or decreased movement can be associated with discomfort. When we are sitting, the Sacro-iliac joints are in a sustained position which puts the ligaments in the area under tension, which can lead to fatigue and discomfort. Presentations of Sacro-iliac joint pain can present as pain over the buttock, difficulty sitting for a period of time or pain getting up from sitting.
It is not uncommon for the Sacro-iliac joint to be involved when patients present with other injuries such as hip, knee, or disc. This is because the pelvis has been loaded unequally causing it to rotate and compensate for the other injury. In this situation it is important to address this imbalance to allow equal loading of the two Sacro-iliac joints.
There are some simple lifestyle adjustments that we can all make to help prevent Sacro-iliac discomfort. These include:
1. Refrain from crossing our legs when sitting.
2. Avoid carrying a heavy handbag on one side.
3. Ensuring that when wearing a backpack, it is worn on both shoulders with appropriately adjusted straps.
4. Avoid sitting with a wallet in your back pocket.
If you would like more information regarding the Sacro-iliac joint and how it functions, please speak to Danielle.
