What are the key clinical features to assess in a patient presenting with knee pain to differentiate between osteoarthritis and meniscal injury?

To differentiate between osteoarthritis (OA) and a meniscal injury in a patient presenting with knee pain, a thorough clinical assessment focusing on history and examination findings is crucial NICE CKS.

Key features for Osteoarthritis (OA):

• A clinical diagnosis of knee OA can often be made without imaging if the patient is 45 years or older, has activity-related joint pain, and has either no morning joint stiffness or morning stiffness lasting no longer than 30 minutes NICE NG226.
• Pain is typically activity-related and worsens with use NICE NG226.
• Stiffness is commonly experienced in the morning, lasting less than 30 minutes, or after periods of rest NICE NG226.
• Patients may report reduced function and difficulty with daily activities NICE NG226.
• On examination, crepitus (a grating or crackling sound) may be felt or heard during knee movement NICE CKS. An effusion (swelling due to fluid accumulation) may also be present NICE CKS.

Key features for Meniscal Injury:

• A history of a specific twisting injury to the knee is often reported NICE CKS.
• Patients commonly present with mechanical symptoms such as locking (the knee getting stuck), clicking, or giving way (sudden instability) NICE CKS.
• Pain is often exacerbated by specific movements like squatting NICE CKS.
• On examination, there may be tenderness along the joint line where the meniscus is located NICE CKS. An effusion may also be present NICE CKS.

Differentiation and Overlap:

• The presence of mechanical symptoms like locking, clicking, or giving way is highly suggestive of a meniscal injury and helps differentiate it from isolated OA NICE CKS.
• While OA pain is typically more generalized and activity-related, meniscal pain can be more localized to the joint line and triggered by specific movements NICE NG226,NICE CKS.
• Morning stiffness lasting less than 30 minutes is a hallmark of OA, whereas it is less characteristic of an isolated meniscal injury NICE NG226.
• It is important to note that individuals can present with both osteoarthritis and symptomatic meniscal tears, which can collectively influence their reported pain and mobility [Luc-Harkey et al., 2018]. Therefore, a comprehensive assessment is vital to identify all contributing factors to the patient's knee pain NICE CKS.