The pre-op assessment was going as planned. Weight, height, blood, ECG, etc. Then the nurse said: "How's your hair?" I'm all for being thorough, but this seemed ridiculous. "Well," I replied. "As you can probably tell, I haven't got as much as I would like." She stared back at me blankly. "What I said was, 'How's your hearing?'"

It turned out that being a bit deaf was no great medical obstacle and I was passed for surgery. At age 55, the moment I had been expecting for the best part of 30 years – and putting off for the past five – had arrived.

I had my first knee operation in the early 80s. I'd been getting a lot of pain and restricted movement, and the surgeon had discovered the end of my femur was crumbling in the knee. His solution was to take a portion of bone from the tibia and nail it on to the knee joint. "It won't last for ever," he said cheerily. "But hopefully it will see you through until we can come up with something better."

The knee lasted better than expected and it wasn't until the mid-90s that it started giving me trouble again. I saw a different surgeon, who was just as downbeat. "I can give you an arthroscopy to clear out any bits of floating bone and what's left of your cartilage," he said. "But the bottom line is that you really need a new knee."

I talked that surgeon into giving me three more arthroscopies but after the last one he said, "That's it. I'm not doing any more. It's pointless." Which is why I made a point of not going back to see him for five years. Eventually, though, the pain became intolerable. I'd long since had to give up all the sports I enjoyed – running, football and tennis – and make do with the non-load-bearing cross-trainer at the gym, but when just walking to the tube became an ordeal, I decided I'd had enough. "Look on the bright side," said my wife. "You might become less grumpy.'

The trouble was I knew what was coming. A Total Knee Replacement (TKR) may be relatively commonplace these days, but it's still not a procedure for wimps. "We'll need to blood-match you in case you need a transfusion. Some patients have excessive bleeding," a nurse had said, not entirely reassuringly. "And we'll also have to give you preventative antibiotics. With a wound that size, infection is always a risk." I had also made the mistake of watching a 10-minute YouTube video of the operation. It was like watching a splatter movie. A 6in incision. Saws, chisels, drills and hammers to bash the ends of bones into some sort of shape to accommodate a heavy titanium covering on the end of the femur and a piece of designer plastic to the tibia. And a lot of blood.

The one piece of good news was that the operation would be done under epidural – better for pain-management apparently – and so though I'd be given a mild anaesthetic to stop me getting bored or becoming a nuisance, I'd be awake for much of the operation. "In what way is that good?" my friend Kevin had asked me, incredulously. "Because I've got a horror of dying under anaesthetic and if I'm awake there's a better chance the surgeon won't be so brutal," I replied. "You're mad," said Kevin. "What better way is there to die than under anaesthetic? You'll never have to fully appreciate just how futile your life was." Thanks, Kevin.

Despite all this, I must have dozed off for much of the operation as I awoke to hear a lot of hammering to a background soundtrack of the Doors. "Nearly finished," said the surgeon. "Your knee was a lot more worn than I thought, but the op has gone well."

"Do you often play the Doors in theatre?" I replied.

"From time to time. You should count yourself lucky you were asleep for Rolf Harris."

"I do. Any chance you could play The End?" Somehow it felt like an Apocalypse Now moment.

"Sure." And he did.

When I was wheeled back to the ward, I wasn't entirely happy to find there was a drain sticking out of my thigh, dripping what looked like rather a lot of blood into a plastic bottle, and that I was also attached to a catheter. Although I had been warned about them beforehand, these were indignities I hadn't seriously considered. I'm not good with dependency issues and these felt like vulnerabilities too far. Overall, though, I was in better shape than I'd expected. The pain wasn't as bad as I had anticipated, but mostly I just experienced a sense of euphoria that I hadn't bled to death on the table. And I also found it quite reassuring to have nursing staff taking an active interest in my blood pressure at regular intervals.

Within 24 hours, the catheter and drain were removed and I'd been turfed out of bed and told to start walking with a Zimmer frame. There was only a slight bend in the knee and my leg didn't feel as if it entirely belonged to the rest of my body, but I could move about. Ish. Getting to the end of the corridor was unbelievably exhausting.

A day later, I was wheeled off to the hydrotherapy pool. This was heaven. Not just because it was warm and soothing, but because it allowed the illusion of movement. It was the pool that gave me hope. I could stand up by myself. Walk by myself – well, after a fashion. It was there I could first imagine having my life back.

"You seem to be doing OK," the doctor and the physio agreed. "You can go home a day earlier, if you want." My wife wasn't quite as pleased about this as me. "You said you would be in hospital for a minimum of four days,' she said. "You can't start changing the arrangements now."

"Why not?"

"Because I'm going out on Friday night."

So another night in hospital it was. Which, on reflection, wasn't such a bad idea as being at home wasn't everything I had imagined. Within just four days in hospital, I'd become institutionalised. I understood the routines and though I had often been catatonically bored, I at least felt safe. At home, even the smallest decision became an effort. Scary even. Should I go stay in bed or go downstairs? Whichever decision I made invariably felt wrong. Worst of all, I hated having to ask my wife and children to do almost everything for me. So I tended to say nothing.

After being at home for a few days, a mild depression set in. Not the heavy, all-consuming, get-me-to-a-shrink-ASAP depression I've had so often in the past. Rather, just a low-grade persistent depression, where everything felt a bit pointless, where what little I could force myself do left me exhausted and sleep was a mixed blessing: a series of vivid nightmares followed by waking up having bent my leg into some weird painful position.

None of which should have been a surprise, because my recovery was going exactly as the surgeon had said it would. "It will be six weeks before you're anything approximating normal," he had said. "It's a big operation. All being well you will be able to drive again after that, but it will be at least three months before you really feel the benefits of your new knee. Take it easy and don't overdo it." I'd nodded to show I understood, but what I'd really been thinking was: "I'm a lot fitter and a lot younger than most people who have this op so I'm going to recover a lot quicker than you think." Idiot. Younger and fitter I may have been, but soft tissue takes its own time to heal.

Still, after about two weeks of this, some strength returned and my mood lightened. The physiotherapy is still brutal. Every extra degree of bend comes at an agonising cost and I'm having to relearn how to walk properly; something I haven't done for years. Nor do I find it easy watching my wife go out to work, my son go off to school and my daughter enjoying life at university: I feel as if my life is atrophying along with my leg and that the world is passing me by. Despite much attention from family and friends and great care from my surgeon and the physios, I frequently feel forgotten.

It's now four weeks since the operation and I still don't feel I've got a handle on the recovery process. I know I should be holistic and learning to love my leg, but I've never been any good at that sort of crap. Most of the time I regard my knee as an alien enemy that's invaded my body, something to be taken on and beaten. And slowly, either because of or despite this combative approach, I'm getting there.

Today my new knee bent to 116 degrees and I managed five minutes on the exercise bike. For the first time, I cried with happiness rather than pain.