How do I know if I broke my kneecap or just bruised it?

Signs that suggest a fracture

• Pain right over the kneecap that is sharp when pressed
• Swelling that develops within hours, sometimes with a tight, full feeling inside the joint
• Difficulty or inability to straighten the knee actively or keep the leg straight while lifting it
• Bruising across the front of the knee in the following days
• A gap, step or grating you can feel over the bone
• Pain that stops you bending the knee much at all

Signs that point more towards a bruise

With a bone bruise or soft-tissue bruise, the knee is sore and may swell, but you can usually straighten it fully, lift the straight leg and walk, even if it is uncomfortable. Pain tends to ease steadily over a week or two.

A soft, fluid-filled swelling sitting on top of the kneecap rather than inside the joint may be prepatellar bursitis, which also follows falls and kneeling. It is managed differently from a fracture.

How it is confirmed

X-rays from the front, side and a special skyline view show most kneecap fractures. A vertical crack may only be visible on one view, which is why several angles are taken. If the X-rays are unclear, a CT or MRI may be used.

Some people have a bipartite patella, a kneecap that developed in two pieces with a smooth line between them. It can look like a fracture on X-ray; comparing with the other knee and the clinical findings helps tell the two apart.

When to be seen and where

If you cannot straighten your knee, have a wound over the kneecap or severe swelling, go to emergency care straight away. If you can walk and straighten the knee but pain over the kneecap persists after a few days, arrange a specialist review. At Aman Hospital in Doha, Dr. Gelber examines the knee, reviews or arranges X-rays and explains whether the injury needs a brace, surgery or simply time.