Hip pain involves any pain in or around the hip joint.
Pain related to the hip is not necessarily felt over the hip itself. Instead, you might feel it in the middle of your thigh or in your groin. Likewise, pain felt at the hip may indicate a back problem, rather than in your hip itself.
Pain can originate from structures that are inside the hip joint or from structures around the hip. The hip joint has a space within it, which means that there is a very small amount of fluid inside it to allow the head of the femur to slide in the socket of the acetabulum (hollow inside the pelvis). Any illness or injury that results in inflammation will cause this space to fill with fluid or blood, and this will stretch the hip capsule and cause pain.
The head of the femur and the acetabulum are lined with cartilage that allows the bones to move in the joint with little friction. Also, the socket area is covered with tough cartilage called the labrum. In the same way as with any other joint cartilage, these areas can tear or wear away and cause pain.
There are thick bands of tissue surrounding the hip joint, forming a capsule. These help to maintain joint stability, especially with movement.
Movement at the hip joint is enabled due to the muscles surrounding the hip and the tendons that are attached across the hip joint, allowing movement in different directions. Apart from controlling movement, these muscles act together to maintain stability of the joint. There are large closed fluid-filled sacs (bursas) that surround the areas of the hip where muscles cross each other and allow the muscle and tendon to slide more easily. Any of these structures can get inflamed.
Pain from other sources can be felt at the hip, meaning that while the hip hurts, the problem originates somewhere else. Inflammation of the sciatic nerve as it comes down from the back can cause pain at the hip, especially if the L1 or L2 nerve roots are involved. Other types of nerve pain may show themselves as hip pain, including pain arising in the lateral femoral cutaneous nerve of the thigh, which is often inflamed in pregnancy. Pain from an inguinal hernia can also cause pain that is felt in the hip.
Hip pain is therefore not caused by only one disease or injury and it needs a doctor to find the underlying cause. Without any obvious injury, the diagnosis of hip pain requires an open mind.
Hip pain is often difficult to describe, and patients may just complain that their hip hurts. The location, description, and intensity of the pain and what makes it better and what makes it worse depend upon what particular structure is inflamed or injured
Pain from the hip joint may be felt at the front side of the body as groin pain, over the greater trochanter (place where muscles are attached to the thigh bone) at the side of the body, or at the rear of the body in the buttock. Sometimes the patient may complain of knee pain which has actually originated at the hip.
- Trauma to the hip: As a result of a fall, direct blow, twist, or stretch, the pain is felt almost immediately.
- Overuse injury: The start of pain may be delayed by hours or minutes as inflammation of the muscles surrounding the hip joint go into spasm, or joint surfaces inflame, causing an accumulation of fluid.
- Pain: Most often, pain is felt at the front of the hip, but the joint is three-dimensional, and so, pain may also be felt along the outside part of the hip or even in the area of the buttocks.
- Limp: Limping is the body's way of compensating for pain by trying to reduce the amount of weight the hip has to support when walking. Limping is always abnormal. Also, when limping happens, greater stresses are placed on other joints, including those at the back, knees, and ankles.
- Fracture: With a hip fracture, there is an immediate start of constant pain after the injury and this pain is usually made worse with almost any movement. The leg may appear shorter and turned outward. Pelvic fractures may cause similar pain.
- Sciatica pain: Pain from sciatica tends to start in the back and spread to the buttocks and to the side or front of the hip. It may be described in various ways because of nerve inflammation. Some typical descriptions used for sciatica pain include sharp, burning, or stabbing. The pain of sciatica may get worse when straightening the knee because this stretches the sciatic nerve and may make it hard to stand up from a sitting position, or walk with a full stride. There may also be numbness and tingling. Loss of bowel and bladder function accompanying the pain may warn of a neurosurgical emergency and the presence of cauda equine syndrome, in which the spinal cord is at risk of permanent damage.
- Arthritis: If arthritis narrows the hip joint or impinges on the way the femoral head can glide in the acetabulum (concave surface at the pelvis), or if there is a tear in the cartilage or labrum, the pain may be accompanied with a "catch," or a feeling that there is something impeding hip movement.
Pain from arthritis tends to worsen after a period of inactivity and gets better as the joint "warms up" with use. But as activity increases, the pain returns.