One of the most common causes of chronic hip pain is arthrosis. The most common types of arthrosis are osteoarthritis, degenerative arthropathy, osteoarthrosis and deforming osteoarthritis, among others.
Osteoarthritis is a degenerative process that develops in hyaline cartilage, which decreases in thickness due to the loss of the ability to retain water. The joint space appears narrowed on x-ray scans.
When the acetabular and femoral head cartilage decreases in thickness, subchondral sclerosis occurs, which is the bone reacting to hyaline cartilage failure.
Hip osteoarthritis is more common in older people. But age is not the only factor that causes osteoarthritis. Various local and general pathologies also play a part.
A young hip has smooth, transparent, thick cartilage the colour of steel. With use, this cartilage decreases in thickness, becomes opaque, less elastic, less shiny and yellowish. The load-bearing surfaces become less smooth.
Closer observation reveals cartilage that is more fibrillar, even displaying small surface detachments.
From the age of 55 onwards, one may observe ulcerations and erosions caused simply by wear and ageing of the joint and without any known pathological alterations, that leave the subchondral bone without its cartilaginous cover.
There is supero-external compressive load on the hip at the socket and the femoral head. This is where more frequent and more severe joint changes are observed. Greater socket wear is found at this level (the horizontal area), than at the vertical area where wear is less frequent.