In which cases should I refer a patient with a Baker's cyst to secondary care for further evaluation or intervention?

Refer a patient with a Baker's cyst to secondary care for further evaluation or intervention in the following cases:

• If any red flags are identified or there is a high suspicion of a serious alternative diagnosis such as deep vein thrombosis (DVT), arrange same-day assessment in secondary care NICE CKS.
• If the diagnosis of the popliteal fossa swelling is unclear, consider referral to a rheumatologist or orthopaedic surgeon NICE CKS.
• If symptoms are troublesome despite conservative measures (such as analgesia and physiotherapy), or if the cyst is very large, refer for specialist assessment NICE CKS.
• If specialist treatment of an underlying knee joint disease is required, such as inflammatory joint disease, refer to an appropriate specialist (rheumatologist or orthopaedic surgeon) NICE CKS.
• In children, refer to a paediatric orthopaedic surgeon if symptomatic or the cyst is very large, or to a paediatric rheumatologist or paediatrician if an underlying condition is suspected NICE CKS.
• Consider referral if there is persisting knee pain or symptoms for more than six weeks, or if there is a suspected degenerative meniscal tear or other underlying joint pathology requiring further assessment NICE CKS.

Investigations in secondary care may include MRI for detailed evaluation and ultrasound-guided aspiration for fluid analysis. Treatments offered may include aspiration with or without corticosteroid injection, arthroscopy to treat underlying pathology, or surgical interventions NICE CKS.