Semimembranosus Tendinopathy (Semimembranosus Tendonitis)

Introduction

Semimembranosus tendinopathy is a condition where the semimembranosus tendon—part of the hamstring muscle group—becomes irritated or damaged with tendonitis where it attaches to the back and inner side of the knee. This condition causes posteromedial knee pain, which means pain behind and to the inside of the knee (Figure 1). It often happens from overuse, especially in people who are active in sports that involve running, jumping, or sudden direction changes, such as soccer, basketball, or track. Semimembranosus tendinopathy is a specific type of hamstring tendonitis, and it tends to develop slowly over time with repeated strain on the tendon.

How is Semimembranosus Tendonitis Diagnosed?

To diagnose semimembranosus tendinopathy, a doctor will first ask about symptoms, such as when the pain started and what activities make it worse. During the physical exam, the doctor will press on the area behind and inside the knee to look for tenderness and test the strength and flexibility of the hamstrings. If the diagnosis isn’t clear, the doctor may order imaging studies, like an MRI or ultrasound, to get a better look at the tendon and to rule out other causes of knee pain, like a meniscus tear or a Baker’s cyst.

Treatment of Semimembranosus Tendinopathy

Most people with semimembranosus tendinopathy (pain or irritation where one of the hamstring tendons attaches behind the knee) can be treated with conservative (non-surgical) care. This starts with resting from painful activities and using ice to reduce swelling. Anti-inflammatory medications may help relieve pain. As the symptoms improve, a physical therapist will guide the person through stretching and strengthening exercises, especially focused on the hamstring muscles and the muscles around the hip and knee.

A physical therapist treating semimembranosus tendinopathy will often recommend gentle exercises to stretch and strengthen the hamstrings without overloading them. Early on, hamstring stretches such as lying on your back and gently pulling your leg upward with a strap can help improve flexibility. As pain improves, isometric hamstring contractions—pressing your heel into the floor without moving the leg—help build strength safely. Later, bridging exercises (lifting the hips while lying on your back) and eccentric hamstring curls using a resistance band or exercise ball can help restore tendon strength and prevent future injury. The key is to progress slowly and avoid sudden or high-intensity movements that could worsen the tendon irritation. Good posture and proper movement during sports or exercise are also important to help the tendon heal and prevent the pain from coming back.

When Surgery Is Needed?

Surgery is rarely needed for semimembranosus tendinopathy. It would only be considered if the pain does not improve after several months of physical therapy and other treatments –and there is clear evidence of localized pathology such as scarring or tearing of the affected tendon. In these rare cases surgery may may be considered to remove damaged or scarred tissue or repair the tendon.

Long-Term Outlook

The long-term outlook for people with semimembranosus tendinopathy is usually very good, especially if the condition is caught early and treated properly. Most people return to normal activities and sports with little or no lasting pain. However, recovery can take weeks to months, depending on how bad the injury is and how well the person follows their treatment plan. Staying active, using proper technique during exercise, and keeping the muscles around the knee strong and flexible can help prevent future problems.

Edited by Amari Eubanks and Stephen Pinney MD, October 23rd 2025