zitbeenknobbels

Zitbeenknobbels is the Dutch common name for the ischial tuberosities, the two rounded prominences at the lower posterior part of the pelvis. They are part of the ischium, one of the three pelvic bones, and are situated where the buttocks fold when seated. The term is used in both clinical and everyday language to refer to these bony projections.

Anatomy and attachments: Each knob is a bony projection at the lower end of the ischium. The ischial tuberosities serve as the origin for the long head of the biceps femoris, as well as the semitendinosus and semimembranosus muscles. They are typically covered by the gluteus maximus and skin, and their exact prominence varies with body habitus and individual anatomy.

Function and clinical significance: They bear weight when sitting and help stabilize the pelvis. Because of their prominence, Zitbeenknobbels can be a source of discomfort when seated on hard surfaces for extended periods. In wheelchair users or individuals with limited mobility, chronic pressure on these bones can contribute to ischiogluteal bursitis or pressure ulcers. Acute trauma to the area can cause bruising, and in rare cases, an avulsion fracture of the tuberosity may occur in young athletes.

Management and care: Prevention focuses on cushioning and relief of pressure during sitting, along with posture changes and ergonomic seating. If pain, swelling, or persistent tenderness occurs, medical evaluation is advised to determine the cause and to guide treatment, which may include rest, padding, physical therapy, or imaging to assess for fractures.