As I posted previously, we're nervously waiting for Penny to be admitted for surgery on her left knee. I rang today and found some more details about the specific surgery. It's not TPLO, but TWO, which stands for Tibial Wedge Osteotomy. The surgeon will cut a wedge out of her tibia, so that the slope of the top of the tibia is changed in relation to the weight from the bone above.
If we've understood correctly, it will then be unnecessary for her to have a cranial cruciate ligament at all. If her ligament has partially broken, which he thinks is most likely, then they'll either take out the ligament, or just pare off the frayed parts, because this fraying causes inflammation.
We went for a walk today without Penny, and I realised how much I'm looking forward to the simple pleasure of walking with her on lead. Of course, it's our aim to play sports again, do fun agility, and maybe dance together - but just to get out of the house together will be a joy, even if we have to spend months sedately walking on lead.