Semimembranosus/semitendinosus tendinopathy of the knee

Anatomy: medial hamstrings at the knee

The hamstrings run along the back of the thigh. The semimembranosus and semitendinosus lie medially and the biceps femoris lies laterally. The attachments on the inside of the knee are particularly relevant for the complaints discussed here.

• Semimembranosus: strong muscle with flat tendon; Posteromedial attachment to the tibia and parts of the posterior joint capsule (oblique popliteal ligament).
• Semitendinosus: slender tendon; Inserts together with M. gracilis and M. sartorius on the pes anserinus (goose foot) on the medial tibia.
• Function: knee flexion and hip extension; Stabilization of the medial knee and posterior capsule structures, especially during load changes and landings.
• Neighborhood: medial collateral ligament, medial meniscus, pes anserinus bursa, Baker's cyst (popliteal cyst).

What is Semimembranosus/Semitendinosus Tendinopathy?

Tendinopathy is a painful dysfunction of the tendon caused by excessive or incorrect loading and the resulting tissue changes. It is not pure inflammation (“-itis”), but often a remodeling process of the tendon with reduced resilience. Acute inflammation and irritation of the bursa (bursitis) can also occur.

• Semimembranosus tendinopathy: pain tends to occur posteromedially in the popliteal fossa and on the posterior inner tibial plateau.
• Semitendinosus tendinopathy: Pain tends to occur on the medial-anterior tibia in pes anserinus (distinction from pes anserinus tendinitis is clinically important).
• Triggers: repeated tensile stress, eccentric peak loads, sprinting, stopping and jumping movements, steep downhill running, deep squats with valgus stress.

Who is particularly affected?

• Runners (especially interval or hill runs, quick changes of pace).
• Ball and kick sports (football, handball, tennis) with repeated sprints and changes of direction.
• Strength training (squats, lunges, deadlifts) for technique or progression errors.
• Occupations/activities that involve frequent climbing stairs, squatting or heavy lifting.
• History of hamstring injuries or knee problems.

Causes and risk factors

• Training errors: increasing volume, intensity or pace too quickly; insufficient regeneration.
• Strength and coordination deficits: weaker eccentric hamstrings, insufficient gluteus medius/maximus, trunk stability.
• Leg axis and biomechanics: dynamic valgus, foot overpronation, leg length difference.
• Previous injuries: Hamstring strains, meniscus or ligament lesions can alter load distribution.
• Systemic factors: higher training or everyday stress load, lack of sleep; Metabolic or rheumatic diseases can impair healing.

Typical symptoms

• Locally tender area on the inside of the back of the knee (semimembranosus) or further forward on the shinbone (semitendinosus/pes anserinus).
• Pain when starting, increased strain when sprinting, running downhill, going down stairs, doing deep squats or taking long strides.
• Drawing or stabbing pain when actively bending the knee against resistance.
• Morning stiffness, possibly rubbing noise/crepitus; occasionally swelling with accompanying bursitis.
• Persistent pressure pain after exertion; Sitting with a severely bent knee can be uncomfortable.

Differential diagnoses

• Pes anserinus tendinitis/bursitis (further anterior on the medial tibia).
• Medial collateral ligament (MCL) irritation or partial tear.
• Medial meniscus (posterior horn) – load-dependent inner knee pain, feelings of pinching.
• Baker's cyst (popliteal cyst) - pressure/tightness in the back of the knee.
• Biceps femoris tendinopathy (lateral), popliteus tendinopathy.
• Myofascial pain syndrome, referred pain from the hip/lumbar spine.
• Deep vein thrombosis of the leg (rare but important): sudden swelling/warmth, pain at rest - emergency evaluation.

Diagnostics in practice

Diagnosis is based on history, clinical examination and, if necessary, imaging. The exact location of the pain and the assessment of the stress reaction are crucial.

• Anamnesis: training history, stress profile, previous injuries, pain-modulating factors.
• Clinic: Palpation of the tendon attachments (posteromedial vs. pes anserinus), pain during isometric/concentric knee flexion, functional chain analysis (leg axis, hip/trunk stability, arch of the foot).
• Ultrasound: dynamic visualization of the tendon/bursa, thickenings, hyposignal zones, sliding behavior; precise guidance for injections.
• MRI: if symptoms persist, partial tear is suspected, meniscus/ligament involvement or the diagnosis is unclear.
• X-ray: rare, for bony attachments or axis issues.

Conservative treatment: evidence-based and individual

The aim is to gradually normalize the load on the tendon. Most patients benefit from structured training tailored to pain and function. Medication and passive measures can provide initial support, but do not replace active rehabilitation.

• Example exercises (individual adaptation in practice):
• Isometric hamstring holds with 30–60° knee flexion (5×45–60 s, low pain).
• Pelvic raises/bridges, single-leg bridge, hip hinge (Romanian deadlift) with low load, increasing later.
• Gliding exercises (hamstring sliders) and eccentric leg curls; Nordic Hamstring only in later phases if well tolerated.
• Hip abductor training (e.g. side plank with abduction), core stability.

Options for treatment resistance: injections and technical procedures

If there is no sufficient improvement despite consistent active therapy over several months, targeted additional measures can be considered. We discuss benefits, risks and alternatives transparently.

• Ultrasound-targeted peritendinous injections: In selected cases with severe bursal irritation, a low-dose peritendinous (not intratendinous) corticosteroid in combination with local anesthetic can reduce pain in the short term. Use cautiously, after weighing up the risks and benefits.
• Autologous conditioned plasma (PRP): possible for chronic tendinopathy. Study situation heterogeneous; potential benefit with a low rate of side effects. Expectation management and implementation during rehabilitation are crucial.
• Extracorporeal shock wave therapy (ESWT): can be helpful for tendinopathic pain; Evidence moderate. Combination with active training recommended.

Surgery – rarely required

Surgical therapy should only be considered if there are clear structural problems and persistent symptoms despite conservative treatment being exhausted. Possible procedures include selective debridement, scar/adhesion release or – in exceptional cases – partial release. Decisions are made individually, based on imaging, functional status and personal goals. An intervention does not guarantee freedom from symptoms and requires consistent follow-up treatment.

Rehabilitation and return to sport

Prevention and everyday tips

• Control your load wisely: 10% rule for volume/intensity, plan deload weeks.
• Qualitative warm-up: dynamic mobility, activation of hip extensors and hamstrings.
• Strength training: eccentric hamstrings (e.g. Nordic in later phases), hip abductors, core.
• Fine-tuning technique when running and lifting; appropriate shoes, terrain varies.
• Regeneration: sleep, nutrition, breaks - do not underestimate the risk factor for tendinopathy.

Course and prognosis

With early diagnosis and consistent, stress-adapted therapy, symptoms often improve within 6-12 weeks. Chronic courses can take several months. The prognosis depends on training control, exercise consistency, accompanying factors (leg axis, previous injuries) and realistic goals. Relapses can be significantly reduced through long-term strength/coordination care and clever stress planning.

When should I seek medical advice?

• Sudden severe pain with hematoma or loss of function (suspected rupture).
• Pressure pain with pronounced swelling, redness, overheating or fever.
• Persistent nighttime pain at rest or increasing discomfort despite rest.
• Swelling/tension in the calf/back of the knee with shortness of breath/chest pain – emergency (rule out thrombosis/embolism).

Your orthopedic contact point in Hamburg

In our practice at Dorotheenstrasse 48, 22301 Hamburg (Winterhude), we combine precise clinical examinations with modern sonography to reliably classify tendon and bursa involvement. We will work with you to develop an individual rehabilitation plan that is suitable for everyday use and sports – conservatively oriented, transparent and targeted. You can easily receive appointments via Doctolib or by email.