A 22-year-old woman who works as a cleaning lady presents with one week of left knee pain with acute onset, erythema, swelling over the anterior knee, and pain on knee flexion. Most likely diagnosis?

• A. Chondromalacia patella
• B. ACL tear
• C. Medial meniscus tear
• D. Prepatellar bursitis

Answer: (A)

Anterior knee pain in a young woman who kneels at work points toward patellofemoral joint irritation from chondromalacia patella. When the cartilage under the undersurface of the patella softens or roughens, the patella tracks poorly as the knee bends, causing pain that is felt at the front of the knee and worsened by knee flexion activities like squatting, stairs, or kneeling. This pattern fits the presentation: anterior knee pain with acute onset and pain on flexion in a young, active individual with repetitive knee bending.

A few clues help distinguish this from other causes. An ACL tear usually follows a clear injury with a sense of giving way and instability, not just anterior knee pain. A medial meniscus tear tends to produce joint line tenderness and mechanical symptoms such as locking or catching. Prepatellar bursitis would typically present with a more prominent, localized swelling directly over the patella and warmth from bursal inflammation, often with less emphasis on pain specifically during knee flexion.