Causes
In a healthy person, the thigh sits above the head of the thigh in the acetabulum, which belongs to the hip bone. The ball makes normal movements in the leg possible. Muscles and ligaments stabilize the hip joint and hold the head of the thigh in the socket.
The so-called joint lip encloses the joint head and seals it. If the neck of the femur is anatomically too wide or the acetabulum too deep, the thigh is in direct contact with the joint lip during every movement, striking it with every movement. This can result in injuries to the joint lip and cartilage surfaces.
In some cases, parts of the cartilage and the joint lip can also become detached. If there is an impact during leg movements for a long time, sometimes irreversible damage to the bones occurs. In addition to further tears in the structures close to the joint, degenerative changes may also occur, better known as osteoarthritis. The mechanical obstacle described, which causes pain with every movement, is called impingement syndrome.
Forms
There are numerous subforms of a hip impingement syndrome. In the so-called Cam Impingement (CAM) the femoral head is too wide compared to the neck. This means that the head no longer fits snugly in the socket, which means that the joint head is pushed out of the socket a little further during movement.
If fast or stretching movements are made, the femoral head eventually tears or tears the cartilage and the joint lip. The further the femoral head rotates out of the socket, the more bone rubs against the surrounding structures, which can lead to very severe pain. If excessive pressure from the femoral head on the acetabulum leads to injuries of the acetabulum, the acetabulum may stretch, causing the joint lip or cartilage to tear.
The joint lip is thinned out and pushed to the side. It is replaced by a bone ring that is more stable and less shaped than the joint lip. The disadvantage of this is that the probability of the femoral neck striking is higher with every movement. An impingement that originally originates in the joint socket is known as pincer impingement.Massive damage to the surrounding bone and cartilage material also results in arthrosis. In many cases, it is not an isolated form of impingement syndrome, but a mixed form.
