He probably tore the ligament that keeps it in place.

The bones broke and weren’t set properly, so they fused together

It wss a joke about how coffe tables are my feets arch enemy, frozengryo makes a better point that I would be more likely to make more bones bashing them on a coffee table then lose them.

I’m not a doctor but I’ll go ahead and say that yes, you are a medical curiosity the likes of which humanity has never before seen!

Full disclosure: I have no idea what I’m talking about and completely made that up.