She made the diagnosis by eliciting a full "drawer movement" (indicating a lack of attachment between the tibia and femur) and noting the joint effusion (swelling) and buttresses (soft tissue inflammation) that were present. Believing that Kodi's cruciate was completely torn removed all doubt -- we felt surgery was the only realistic choice at that point. (Note: The ligament turned out to be only partially torn, as Dr. Kraus found during the surgery. It would need to have been repaired nonetheless, so in the end it didn't matter.)
(NOTE: See Kramer's story and the accompanying comments from Dr. John Payne for more on the risks of this procedure. Kramer has had an exceptionally difficult time recovering from his TPLO.)
Dr. Norris showed me the metal plate that will be used to hold the fractured bone together -- it's smaller than I expected, a few inches long and skinny, with holes for the screws. She keeps it on her keychain.
I asked about the issue of stairs, since we have them at both the front and back entrances. I was told we needed to avoid stairs in general, but that we could use a belly sling to traverse a few steps if needed. We scheduled the surgery for the following week.
We tried to practice carrying him but he is quite heavy -- nearly 100 lbs. -- and was squirmy, so we decided it was too risky. There seemed to be no choice -- Kodi would have to spend the first part of his recovery isolated from us in the foyer.
That left two options for recovery -- Kodi lives in the foyer inside the front door for six weeks, or he lives in the living room and goes potty on the deck. He'd be pretty isolated and sad in the foyer, but it's not a bad space -- big enough for a dog bed, a blanket and his mesh tent crate. Nice and cool, which he likes. Has the advantage of easy access outdoors, so he can get fresh air. Also can get to the car to go to hydrotherapy, which wouldn't be an option if we moved him upstairs. In the living room he'd be in an xpen, just as small a space, but would be able to see and interact with us, which would help his spirits a lot. We decided to start with the foyer either way, and consider a move to the living room later, after his recovery was well underway.
See how the surgery went and how Kodi's doing now ...
November 1999
Lameness. Kodi was having trouble getting up from naps, just a slight stiffness or slowness. It was related to his back end but didn't seem to be one leg more than the other. I was mildly alarmed since Kodi's hips had always been fine (he's dysplastic in both elbows, but his PennHip and OFA hip scores were no worse than average, and he'd never limped in the rear before).
December 1999
Lyme? Our female Berner Maddie was diagnosed with an acute case of Lyme disease. One of the symptoms of Lyme is severe arthritis. Could this be what Kodi was suffering from? When a Lyme titer revealed some exposure, we decided with our local vet to put him on a two-week course of antibiotics and see if he improved. (Tufts later pointed out that Lyme typically results in poly-arthritis, affecting the entire dog, so it was unlikely that was what we were seeing.) Kodi did seem to get better through January, for whatever reason, but by February was becoming visibly lame in the left rear leg.
February 2000
First diagnosis. Another vet visit. After manipulating the knee, the local vet said he suspected cruciate but that we'd need a diagnosis from an orthopedic specialist to know for sure. Since we had a good friend whose own Berner was successfully avoiding surgery through a course of supplementation and homeopathic treatment, we decided to rest Kodi, learn more about our options and then choose a course of action. 
Note: Today, our friend's Berner has gone more than three years with a partial tear, but you'd never know it. He takes strenuous hikes on a regular basis and has earned his CD and his HIC along the way. Our friend's experience, and our background in feeding a raw diet and choosing non-traditional approaches in our animals' care, led us to regard surgery as a last-resort alternative, not a foregone conclusion.
March - April 2000
Waiting for our consultation. Kodi's injury seemed to level out. We found he could walk off-leash in the woods with me for about 20 minutes every third day -- any more and he'd be sore and unhappy later.
May 16, 2000
The last straw. Kodi leapt over a large fallen log on our walk -- I was checking for the best way to skirt around it when he sailed over. Even before his cruciate injury he was never much of a jumper (we never encouraged it because of his unstable elbow structure), so it caught me by surprise. He seemed fine immediately after and we finished our walk, but later in the day was up on three legs and remained very lame right up until he went in for surgery two weeks later.
May 25, 2000 (6 days prior to surgery)
Consultation. Decision time. Met with Dr. Jana Norris, orthopedic resident at Tufts University Veterinary School in Grafton, Massachusetts. Dr. Norris took a full history of Kodi's lameness, discussed the TPLO and other surgical options in general, and said she believed that Kodi's cruciate was completely torn. 
TPLO. According to Dr. Norris and Dr. Karl Kraus (who will perform the TPLO), when comparing the various types of canine cruciate surgery, TPLO recovery is not necessarily shorter but is significantly more pain-free for the dog. Dr. Kraus also said that of the TPLO's he's done, two-thirds of the dogs have had "amazing" results -- much better than with the other types of surgery -- and the remaing third have had results "as good as" the other types of surgery. Still, he cautioned that it's not "the best thing since sliced bread" and warned me to be skeptical of the "hype on the Internet." The risk may be higher in some ways since the tibia is actually fractured and a metal plate in installed -- there's a risk of infection, the fracture could fail to heal, the screws could fall out of the plate, etc. Tufts reports only 1% of cases ever have a problem of that nature. Any major surgery is risky, of course, and because of that we wanted to maximize the value -- get the best possible result. To us that seemed to be the TPLO.
May 28, 2000 (3 days prior to surgery)
Preparing for the recovery. My husband and I went to Home Depot and bought some boards and industrial-type carpet with a "nubby" texture to make ramps. The car ramp was easy and a success, and we practiced having Kodi walk slowly up the ramp into the car and back down again. The wider, longer ramp we'd intended to use for the front stairs didn't work out as well -- the angle was simply too steep. Even our agility-girl Maddie had trouble walking up it -- there was no question it would be as hard on Kodi as using the actual stairs, so we had to abandon that idea.
May 30, 2000 (1 day prior to surgery)
NO stairs. I spoke with both Dr. Kraus and Dr. Norris (the resident). They weren't kidding about no stairs. SIX weeks, NO stairs. They were both quite emphatic. It didn't seem to match up with what I'd heard earlier. Had Tufts been over-eager to convince me to have the surgery? Had the stairs issue somehow been glossed over, or had I simply heard what I wanted to hear?
May 31, 2000 (surgery day)
The Big Day. Dropped Kodi off in Grafton at 8:30 AM. He went willingly with the vet tech but shot me a startled look and tried to pull back as they took him through the door into the back. Poor guy -- he has no idea.