What is the hip joint?
The place where the rounded top of the thighbone (head of the femur) meets the pelvis is called the hip joint. Within the pelvis, the acetabulum is a rounded cup-like structure in which the rounded top of the thighbone sits. It is called a 'ball and socket' joint. The ball is the head of the femur and the socket is the acetabulum.
This diagram shows the normal structures in the pelvis and the second diagram shows the hip joint in more detail.
What are the main reasons for needing a hip replacement?
There are two main conditions that can end up with you needing a hip replacement:
- If you have arthritis in your hip:
- Arthritis means inflammation of a joint.
- Osteoarthritis is the most common cause of arthritis in the hip and the most common reason for needing a hip replacement.
- Rheumatoid arthritis is a less common cause. About one person out of every 21 who has a hip replacement has rheumatoid arthritis.
- There are other causes of arthritis that may lead you to needing a hip replacement.
- If you break your hip (hip fracture):
- A hip fracture is a fracture of the top part of the thighbone (femur). The fracture can be of the head, of the neck or below the neck.
- Usually a hip fracture is treated by an operation to screw the broken ends back together again. However, if it is the head of the femur that has broken, this is often treated by replacing the broken head of the femur with an artificial head of the femur (prosthesis). This is particularly the case if the broken bits have moved away from each other or if you already have arthritis in that hip joint.
Further reading and references
Primary Total Hip Replacement: A Guide to Best Practice; British Orthopaedic Association (2012)
Arthritis of the hip (end stage) - hip replacement (total) and resurfacing arthroplasty; NICE Technology Appraisal Guidance, February 2014
Would someone kindly explain why, after getting comfortable on my side in bed with no feelings of pain or heavy thighs at all, in the space of about one hour my operated thigh on top feels as heavy...sarah22500
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