Muscles, tendons and ligaments in the knee

Anatomy and function: Who does what to the knee?

The knee joint is dynamically guided by muscles and tendons and statically stabilized by ligaments. Tendons connect muscle strength to bones; Bands limit mobility and protect against misalignments. A balance of strength, flexibility and neuromuscular control is crucial to avoid pain and injury.

• Front part: quadriceps muscle with quadriceps tendon and patellar tendon (patellar ligament) for knee extension.
• Posterior part: Ischiocrural muscles (biceps femoris, semitendinosus, semimembranosus) for flexion and rotation control.
• Medial: Pes anserinus tendons (Sartorius, Gracilis, Semitendinosus) and medial ligament (MCL) for valgus stability and guidance.
• Lateral: Biceps femoris tendon, lateral ligament (LCL) and the iliotibial band for varus stability and lateral gliding control.
• Calf/Posterior: Gastrocnemius medialis/lateralis and popliteus for flexion strength, stability in flexion and rotation control.

Changes to one structure often affect others - for example, shortened calf muscles can increase the pull on the Achilles tendon and, via knee kinematics, also increase the pressure on the front knee. A holistic view of the leg axis is therefore part of every well-founded diagnosis.

Key symptoms of muscle, tendon and ligament problems

The exact location and the stress-related nature of the symptoms provide important information about the affected structure. Often there are gradual onset symptoms that worsen as the load increases.

• Front knee pain: at points on the tip of the patella (patellar tendon) or above the kneecap (quadriceps tendon), starting pain, stairs/jumps painful.
• Medial pain below the joint space: tenderness on the pes anserinus; often mainly when walking downhill.
• Lateral pain: on the outside of the joint space or on the fibular head region (biceps femoris) or band-like on the thigh (iliotibial tract).
• Posterior knee/calf pain: irritation of the hamstrings, gastrocnemius, or popliteus; pulling, cramp-like or stabbing when pushing/starting.
• Ligament injuries: feeling of instability, capsule swelling, pain-related protective posture; With the MCL, pressure pain and valgus pain medially.
• Additional signs: swelling, morning stiffness, exertion-related warming, occasionally rubbing noises or snapping tendons.

Sudden pain with loss of function (e.g. extension deficit) indicates a relevant injury and should be promptly clarified by a doctor.

Common diagnoses – overview and in-depth information

The following clinical pictures affect the muscles, tendons and ligaments around the knee. For details, causes and treatment options, click on the relevant subpages:

• Patellar tendinopathy (jumpers knee): stress-related pain in the patellar tendon, especially a. in jumping/speed sports. → Underside: patellar tendinopathy (jumpers knee).
• Quadriceps tendinopathy: pain above the kneecap; often after load peaks or when there is a strength deficit. → Underside: Quadriceps tendinopathy.
• Pes anserinus tendinitis: tender, often nocturnal pain medially below the joint space. → Underside: Pes anserinus tendinitis.
• Biceps femoris tendinitis: lateral, pulling pain on the fibular head, often during sprinting/alternating loads. → Underside: Biceps femoris tendinitis.
• Semimembranosus/semitendinosus tendinopathy: posterior knee pain, starting pain, possibly tendon snapping. → Underside: semimembranosus/semitendinosus tendinopathy.
• Gastrocnemius tendon irritation: calf pain, esp. a. at impression/rise; Differentiation from muscle bundle injury is important. → Underside: Gastrocnemius tendon irritation.
• Popliteus tendinopathy: deep, posterior-lateral pain, often during downhill running. → Underside: Popliteus tendinopathy.
• Myofascial pain syndrome of the knee: trigger points, radiating pain, functional imbalances. → Underside: Myofascial pain syndrome of the knee.
• Overload through sport (running, jumping, squats): training errors, progression too quickly, change of surface. → Bottom: Overload due to sport.
• Medial ligament injury (MCL): from strain (grade I) to partial tear (grade II/III); Usually can be treated functionally conservatively. → Underside: medial ligament injury (MCL).

There are also other causes that we take into account in the differential diagnosis, such as meniscal lesions, pain associated with osteoarthritis, irritation of the bursa or systemic inflammatory diseases. You can find suitable overview pages in the internal links below.

Causes and risk factors

Most complaints arise from multifactorial causes. In addition to the pure tissue stress, regeneration, technology, footwear and leg axes play a role. A structured cause analysis is therefore part of the therapy.

• Rapid increase in training, high jumping/eccentric portions, monotonous repetitions.
• Muscular imbalances (especially quadriceps/hamstrings/gluteal muscles), limited flexibility (calves, hamstrings, hip flexors).
• Leg axis deviations (X-leg/O-leg), patellar mistracking, foot misalignments (overpronation/supination).
• Previous injuries, lack of basic endurance, inadequate warm-up.
• External factors: change of surface/shoes, hard floors, cold temperatures.
• Systemic/metabolic: diabetes, thyroid; rarely drug influences (e.g. fluoroquinolones, statins).
• Inflammatory rheumatic causes involving tendon insertions (enthesitis) – clarification if appropriate indications are given.

Diagnostics: targeted and gentle

We start with a precise anamnesis, followed by a structured clinical examination. The aim is to identify the affected tissue, understand the stress relationship and recognize dangerous factors.

• Clinic: Inspection, palpation of pain points, functional and stability tests (e.g. valgus stress for MCL), mobility and strength screening.
• Ultrasound (high resolution): dynamic assessment of tendon structure, blood flow (Doppler), bursae; Follow-up check without radiation.
• MRI: if symptoms are unclear, partial/ruptures are suspected, accompanying pathologies or treatment failure.
• X-ray: to assess bony avulsions, calcium deposits, patella height; used cautiously.
• Laboratory: only if systemic inflammatory genesis or infection is suspected.
• Functional analysis: gait analysis, jump/landing control, leg axis and core assessment.

Important: Imaging complements clinical assessment, but does not replace it. The findings should always be correlated with your complaints and goals.

Therapy: conservative first – individually dosed

Most knee muscle, tendon and ligament problems can be successfully treated with a structured, conservative approach. The central elements are load control, progressive training and the optimization of leg axis control. We discuss transparently which measures make sense and which expectations are realistic.

Rehabilitation duration varies depending on structure and chronicity: from a few weeks (ligament strains) to several months (chronic tendinopathies). Patience and consistent self-training are crucial.

Surgical options – rarely necessary, clearly indicated

Surgery is the exception for muscle, tendon and ligament problems in the knee. It can be considered in cases of acute ruptures (e.g. patellar or quadriceps tendon rupture), lack of response to structured conservative therapy or severe instability.

• Tendon ruptures with loss of function (e.g. no active knee extension): prompt surgical reconstruction is often recommended.
• Higher-grade MCL lesions with persistent instability: individual decision based on clinical and imaging assessment.
• Chronic, therapy-resistant tendinopathy: selective debridement/release procedure - only after at least several months of conservative treatment and weighing up the benefits and risks.

We advise you with an open mind, determine the indication carefully and, if necessary, coordinate surgical care in a suitable center. We do not make a promise of healing; What counts is well-founded information and realistic goals.

Prevention and self-exercises: resilient instead of overloaded

Prevention does not mean protection, but rather wise exposure. A balance of mobility, strength and technique reduces the risk of irritation and injury.

• Warm-up 10-15 minutes: circulation, mobility (hips, ankles), light activation (mini-squats, step-ups).
• Control progression: Moderately increase the volume/intensity per week (e.g. 5–10%), plan load peaks, incorporate deload phases.
• Strength base: 2-3 times/week lower body and hip stability (gluteus medius/maximus), eccentric focal points for tendon resilience.
• Flexibility: Calf, hamstrings, hip flexors stretch in a measured manner; prefer active mobility work.
• Technology & Shoes: Slightly increase your running cadence (e.g. +5-10%), avoid surfaces that are too hard and shoes that are very worn, check whether you need insoles.
• Regeneration: sleep, stress management, adequate energy and protein intake; Couple load peaks with regeneration.

If necessary, we will put together an individual exercise plan for you and accompany the progression. If pain is present, the home program should be adapted to the symptoms.

When should I seek medical advice? Warning signs

• Sudden, stabbing pain with “snapping” and immediate loss of function (e.g. no active stretching).
• Severe swelling, hematoma or visible misalignment/instability.
• Fever, redness, severe pain at rest or throbbing at night (suspected infection).
• Calf pain with swelling/warmth and signs of shortness of breath (suspicion of thrombosis) – emergency evaluation.
• Persistent symptoms > 6–8 weeks despite adequate rest and exercise therapy.

If you experience such signs, do not hesitate to seek medical examination. Early diagnosis improves the treatment strategy.

This is how we work – your orthopedics in Hamburg

In our practice at Dorotheenstrasse 48, 22301 Hamburg, we combine careful clinical examination, modern ultrasound diagnostics and clear, everyday therapy planning. We value understandable information, realistic goals and conservative treatment with targeted training control.

• Individual diagnosis and step-by-step plan instead of scheme F.
• Close collaboration with physiotherapy, sports science and – if necessary – operational partners.
• Regular progress checks and objective criteria for increasing the load.
• Optional additional procedures (e.g. ESWT, PRP) only after benefit-risk assessment and an informed decision.

To make an appointment, please use Doctolib or write us an email. We look forward to your request.