Ruptured Baker's cyst: ward management in the UK

1. Immediate assessment

• Observations and pain score.
• Examine both legs: calf circumference, erythema, tenderness, oedema, distal pulses, sensation and motor function.
• Examine knee for effusion, inflammatory arthritis, osteoarthritis, trauma or infection.
• Ask about VTE risk factors, anticoagulants, bleeding risk, fever, recent knee surgery or infection.
• Assess for PE symptoms: chest pain, dyspnoea, haemoptysis, syncope.

2. Exclude DVT

• Apply local trust VTE pathway, usually Wells score plus D-dimer where appropriate.
• Arrange urgent venous duplex ultrasound for suspected DVT. It may also show the popliteal cyst and calf fluid tracking from rupture.
• If DVT remains clinically likely despite a negative initial scan, follow the local serial-ultrasound pathway.
• Do not label it solely as a Baker's cyst if thrombosis has not been adequately excluded. A cyst and DVT can coexist.

3. If DVT is excluded and rupture is confirmed or strongly suspected

• Analgesia: paracetamol first line.
• Consider an oral NSAID, such as ibuprofen or naproxen, only if suitable. Avoid or use caution with AKI/CKD, peptic ulcer disease, anticoagulation, heart failure, uncontrolled hypertension, pregnancy and frailty. Consider gastroprotection where indicated.
• Ice wrapped in cloth for short intervals, elevation when resting, and compression only if comfortable and there is no arterial concern.
• Encourage gentle mobilisation as tolerated. Temporary crutches may help if weight bearing is painful.
• Physiotherapy advice: maintain knee and ankle movement, then strengthen quadriceps/hamstrings once acute pain settles.
• No antibiotics unless cellulitis, septic arthritis, or another infection is suspected.
• No anticoagulation for the cyst itself. Give standard inpatient VTE prophylaxis only if indicated by the patient's admission-related VTE and bleeding-risk assessment.

4. Treat the underlying knee pathology

5. Escalate urgently if

• rapidly worsening pain or tense calf
• pain out of proportion, pain on passive stretch, paraesthesia, weakness, pallor, cool foot or reduced pulses: consider compartment syndrome
• fever, marked erythema, systemic illness or a hot swollen knee: exclude septic arthritis/cellulitis
• significant bruising or falling haemoglobin, especially with anticoagulant use: consider haematoma
• chest symptoms or haemodynamic instability: assess for PE
• failure to improve, recurrent large swelling, uncertain diagnosis, or concern for mass/arterial pathology.

Typical ward documentation / plan

Acute unilateral calf swelling likely due to ruptured Baker's cyst (pseudothrombophlebitis), but DVT excluded by duplex ultrasound. Neurovascularly intact, no features of compartment syndrome or sepsis. Manage with regular paracetamol +/- appropriate NSAID, elevation, ice, mobilisation as tolerated and physiotherapy advice. Safety-net for worsening pain/swelling, neurovascular symptoms, fever or PE symptoms. Address underlying knee disease via appropriate outpatient follow-up.