Hi John, I’m not sure I can help, but since you asked me… here’s my own experience:
I kept fit for 9+ months during my kneecap fracture solely by doing isometrics (1hr+ each day, about every 3 days, off), and for a period of 2 months during the summer, I was also swimming.
It worked for me… But to be honest, I’m not sure if iso’s slowed down my recovery process, because if you don’t do them right pressure goes on the knee. And forget lunges.
The first doctor had told me I would need 3-6months, but it took nearly a year. Although others told me that such injury takes 6-12 months… So I dont’ know.
Of course I was never too nice to it… you know me.
Swimming bothered me sometimes when kicking, but 90% of the time it felt fine.
I’m sure it varies with the injury.
Deep water running was great, as long as I controlled the angles, since certain degrees felt uncomfortable.
Swimming every day for prolonged time was too boring for me. Not so much the effort itself, but the whole process… swim suite, goggles, towel, sandals, cap, changing, showering, swimming… then showering and dressing again… bliah.
Learning and experimenting with strokes was very fun though =)
Isos are more boring as a task, but I could just stop what I was doing at any time and work almost all the muscles in one hour.
The program I used not only helped my strength, but aerobic conditioning as well, as the heart rate jumped up pretty fast.
For now, whenever I get knee irritation, quad strengthening is the key. Just 5 minutes of wall sit does the trick for me.
I hope something helps…