Pain at the Back of the Knee
Tightness, aching, or swelling in the popliteal space behind the knee, sometimes associated with fullness or difficulty bending.
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What does this symptom mean?
Pain at the back of the knee is commonly caused by an accumulation of joint fluid that herniates backwards (a Baker's cyst), posterior meniscus tears, or hamstring tendon strains. It can make the back of the knee feel full, tight, or restricted when bending. Wording is cautious: posterior pain is often secondary to an underlying joint condition, and a clinical assessment is advised.
Anatomical Overview
Important — Educational Information Only
Pain location alone cannot determine the cause of knee symptoms. This map provides educational information about anatomical structures and possible associations. It is not a diagnostic tool. A clinical examination by a qualified specialist is required to determine the cause of your knee pain.
Knee Pain Location — Educational Guide
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Select a numbered hotspot on the Back (Posterior) photograph or use the Prev/Next buttons below to browse.
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Front (Anterior) View
Around the Kneecap (Anterior)
Pain around or behind the kneecap (patella). Often worsened by stairs, squatting, or prolonged sitting.
Outer Joint Line (Lateral)
Pain along the outer joint line. Often related to sports injuries, pivoting movements, or lateral compartment problems.
Inner Joint Line (Medial)
Pain along the inner side of the knee joint line. The medial compartment bears the majority of weight-bearing load.
Back (Posterior) View
Behind the Knee (Posterior)
Pain, swelling, or fullness in the hollow behind the knee (popliteal fossa). Often secondary to an internal joint problem.
Inner (Medial) View
Medial (Inner) Compartment
Pain along the inner side of the knee. The medial compartment is the most commonly affected by arthritis and meniscal tears.
Outer (Lateral) View
Lateral (Outer) Compartment
Pain along the outer knee compartment. Lateral problems are less common but frequently sports-related.
Symptom-to-Recovery Pathway
Standard Patient Journey Pathway
How the symptom may present
Patients describe this symptom in various ways depending on its trigger and severity:
Possible causes
The possible causes listed below are not exhaustive. One symptom can have several underlying causes, and a clinical assessment is typically required to confirm a diagnosis.
Baker's Cyst
A fluid-filled swelling that develops at the back of the knee, usually arising from an underlying joint problem like arthritis or a meniscus tear.
Meniscal Tear
A tear in the shock-absorbing C-shaped cartilage discs of the knee, often caused by twisting forces or age-related changes.
Knee Arthritis
Degeneration of the knee joint cartilage leading to progressive pain, stiffness, and restricted mobility.
When to seek urgent advice
Certain symptoms (red flags) indicate the need for prompt clinical evaluation. Seek immediate assessment if you experience:
- Sudden, severe pain in the calf with redness, warmth, and swelling (possible DVT or ruptured cyst)
- You feel unwell or have a high temperature with joint swelling
- You cannot bear weight on the leg
How the symptom is assessed
Your consultant will carry out a thorough assessment to understand the triggers, location, and functional impact of the symptom.
- Physical examination of the popliteal fossa to check for swelling and warmth
- Assessment of knee joint range of motion (flexion and extension checks)
- Evaluation of underlying conditions (arthritis or meniscus signs)
- Checking for signs of deep vein thrombosis (calf tenderness/swelling)
Investigations that may be considered
Depending on the findings of your clinical assessment, your consultant may recommend imaging scans:
Ultrasound scan
confirm a Baker's cyst and evaluate popliteal blood vessels
MRI scan
identify the underlying joint issue (e.g. arthritis, meniscus tear)
What may help initially
For non-urgent presentations, simple self-care and load management can help settle symptoms:
- Relative rest and avoiding activities that require deep knee bending
- Elevation and compression to help reduce fluid accumulation in the back of the knee
- Gentle stretching of the hamstrings and calf muscles
When to arrange a professional consultation
You should arrange a specialist consultation if you experience any of the following:
- The swelling behind the knee is large, painful, or restricts bending
- You experience sudden calf pain and swelling
- The discomfort does not resolve with rest and load modification
Frequently Asked Questions
Would you like an individual knee assessment?
A consultation can help clarify the possible cause of your symptoms and discuss appropriate next steps.
Face-to-face appointments are arranged through the reception team at the chosen clinic. Video consultations use Google Calendar where available.
Next Step: Explore Possible Conditions
Similar symptoms can occur with several different knee conditions. Learn about common diagnoses, how they are assessed, and how force transmission affects joint health.
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Medical Disclaimer
This website provides educational and general information about knee symptoms, conditions, and treatments. The content is for informational purposes only and does not constitute medical advice, diagnosis, or a treatment plan. It should not be used as a substitute for a professional consultation, examination, or clinical decision-making by a qualified orthopaedic specialist.
If you are experiencing symptoms or are concerned about a knee problem, please arrange a clinical consultation. If you have urgent symptoms, severe pain, or are unable to put weight on your leg, please read our urgent advice guidance or contact emergency services immediately (dial 999 or NHS 111).