What should you know about semimembranosus bursitis?

The semimembranosus muscle is one of the hamstrings at the back of the thigh. A bursa near its tendon helps reduce friction as the knee and nearby tissues move. Irritation can produce tenderness at the inner back of the knee, discomfort with bending, or a sense of fullness. Similar symptoms can arise from a tendon problem, meniscus injury, arthritis, a cyst, or another cause of joint swelling, so location alone cannot confirm bursitis. A clinician may examine your knee, movement, and surrounding tendons and decide whether imaging is useful.

Reduce activities that repeatedly provoke the area, such as deep knee bending, hills, or sudden hamstring loading, while keeping gentle pain-limited movement. Ice wrapped in a cloth may ease symptoms for a short period. Do not massage a visibly swollen or hot area. A clinician may recommend an anti-inflammatory medication after checking your medical history, other medicines, and stomach, kidney, heart, or pregnancy-related concerns. If symptoms do not settle, treatment may address hamstring strength, hip control, and the activity that caused repeated irritation.

Arrange medical review if swelling persists, walking becomes difficult, the knee catches or gives way, or pain follows a twist or fall. Seek urgent care for a hot red knee with fever, sudden major swelling, inability to bear weight, or calf swelling and breathlessness. A clinician may consider a cortisone injection or joint aspiration only after assessing the diagnosis and infection risk; these are not home treatments.

Ask whether the swelling is in a bursa or inside the joint, which activities to modify, and when strengthening should begin. Ask whether anti-inflammatory medication, a cortisone injection, or joint aspiration is appropriate and what warning signs should prompt reassessment.