Definition
The ischium (Os ischii) is one of three bones that form the hip bone. The ischium thickens towards the ischial tuberosity (Tuber ischiadicum). On the one hand, this serves as the deepest point of the bony pelvis as a point of support.
On the other hand, many hip and thigh muscles have their origin here. In addition, a ligament (Ligamentum sacrotuberale), which stabilizes the sacro-iliac joint, extends from the ischial tuberosity and prevents the hip – more precisely the sacrum – from tilting backwards. Furthermore, the so-called ischiofemoral ligament extends from the ischium, which runs from the ischium to the femur.
This ligament is responsible for limiting the internal rotation of the leg and for stretching the leg backwards. Since these structures can be irritated, overstretched or even injured, pain can occur in this area – depending on the structure affected. This often occurs after performing unaccustomed sports.
Cause
On the one hand, the bone can be injured by overstraining or falling. For example, the bone may break or be broken, causing pain. An inflammation of the bone tissue can also cause pain in the ischium.
Inflammation of the bone can be caused, for example, by sitting for too long, as is typical for office jobs. In very rare cases, tumors can cause inflammation or brittleness of the bone. However, it is mainly the numerous structures such as muscles, tendons or tendon attachments that are inflamed and originate from the ischium or ischial tuberosity, with tendons being affected more often than muscles.
A pulled muscle or torn muscle fibre can also cause pain. If muscles, tendons and ligaments are not warmed up properly before exercise, the risk of injury is generally greater. Even if you do sports that you are not used to and that are too strenuous for your existing condition, strains and injuries can occur more easily.
Furthermore, many vessels and nerves run close to or through gaps in the bone of the ischium. These structures can also become irritated and cause pain. The ischial tuberosity forms the lowest part of the bony pelvis.
In addition to its supporting function when sitting, the ischial tuberosity (tuber ischiadicum) is a starting point for many muscles, especially the muscles of the back of the thigh. Biceps tendon endinitis is an inflammation of the attachment tendon of the biceps femoris muscle (two-headed muscle on the back of the thigh). Such an inflammation typically results from overloading the muscle.
Biceps tendon endinitis can also be caused by prolonged sitting, as the tendon is irritated by the pressure when sitting. Such an inflammation usually manifests itself not only by pain at the ischial tuberosity, but also swelling, redness and overheating of the affected area can occur. The best way to cure the symptoms is to relieve the affected ischial tuberosity for a longer period of time.
The ischial tuberosity is the starting point for many muscles of the back of the thigh. These include the following muscles: Musculus biceps femoriis, adductor magnus, quadratus femoris, gemellus inferior, semimembranosus and musculus semitendinosus. Overloading can weaken the tendons of these muscles, which can quickly lead to a rupture or tear of the tendon at the ischial tuberosity when it is reloaded.
A very severe sudden trauma to one of the muscles of the back of the thigh can also cause a torn tendon. Such a rupture of the tendon often manifests itself as pain in the affected ischial tuberosity (tuber ischiadicum). The pain is particularly noticeable when the ischial tuberosity is strained while sitting.
The ischial tuberosity is the part of the pelvic bone on which the entire weight of the upper body rests when sitting. A fracture of the ischial tuberosity is comparatively rare, but it can be triggered by a severe trauma such as a traffic accident. A fatigue fracture of the ischial tuberosity is also possible. Depending on the severity of the fracture, treatment is either conservative (sparing the ischial tuberosity) or surgical (using bone screws or plates).
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