The diagnosis of prepatellar bursitis is typically established based on swelling observed at the front of the kneecap and tenderness upon palpation. Increased warmth and redness may also be noted in this area. The swelling is generally soft in consistency with well-defined borders. In advanced cases, pain may be experienced even without direct touch. The vast majority of patients have a history of knee trauma (e.g., a fall) or repetitive microtraumas, such as prolonged work on their knees. In most instances, a diagnosis can be made sufficiently through the patient's history and a physical examination alone.

In rare circumstances, it can develop spontaneously in individuals with rheumatic diseases. For patients with a history of trauma, knee radiographs or computed tomography (CT) scans may be requested to assess the risk of patellar fracture. In cases without a history of trauma, the physician may recommend tissue ultrasonography if deemed necessary. However, if the swelling has been present for a long time and is progressively growing, magnetic resonance (MR) imaging of the knee may be required for differential diagnosis and to rule out potential tumoral formations.