It sounds stupid, but very possible. When you're in fight camp and over-train, you're highly susceptible to injuries when you least expect it as lots of shit on your body has been overly taxed and are busy trying to heal, etc. I remember training hard for a coming fight and was wrecking most everyone during sparring, cardio, everything.... for 3 hours straight. I felt great, then afterward, in the showers.....made a slightly wrong/sudden movement and felt a pop, which ended up being a seriously sprained ankle....from taking a shower. T-Ferg's probably doing things 10x more strenuous.....oh, plus he does stupid shit too like kicking steel pipes....which coincidentally, is putting a shitload of impact onto the ligaments at his knees.