‘What can I do for you then?’

‘Oh, I don’t know what's the matter with me’

‘Give me a clue.’

I’ve just fallen asleep when the telephone rings. Not so deeply asleep that it takes me an age to realize what the noise is, but enough to give me that sickening feeling of being dragged back to reality. I reach across and fumble for the receiver, craning to see the glowing figures of the clock on the far side of the pile of half-read books on the bedside table. Quarter to midnight. It feels like half-past two.

‘I’m terribly sorry to trouble you but my husband has just got home and he’s fallen up the stairs and seems to have broken his knee. I wondered if I should take him to casualty or somewhere…’

Almost all the tiny part of my brain which has woken up is concentrating on finding ways of staying in bed, not to mention going back to sleep. The whole of this meagre brain power now focuses on the patient’s apparent willingness to go to casualty. An appropriate reply is necessary. Think, man, think.

I do see, that’s the funny thing about it. Already, in spite of my sleepiness, I’ve got quite a clear picture in my mind of the scene on the stairs, complete with a provisional diagnosis and a plan of what I ought to do about it.

‘I see… It sounds as though he’s dislocated his knee cap.’

I wonder momentarily whether I could talk her through reducing it herself, then immediately reject this as a silly idea. On the other hand, it is hard to justify a fifteen-mile ambulance journey and then hours of waiting in casualty. And then getting home again. I know perfectly well what I’m going to do.

‘How are you going to get him into the car, if he’s like that…’

‘I don’t know… There’s the baby as well…’

‘I see…’

‘I’m terribly sorry to disturb you, doctor.’

‘All right. It’s OK. I’d better come and see him.’

‘I’m terribly sor...’

‘OK. - I’ll be along in a few minutes’

Jersey and trousers on over pyjamas, hunt for socks, check the bleep is on, receive wife’s sympathy, step over the dog on the stairs, through the front door, open the garage, feel for the keyhole in the dark, open the door, start the car. Gales of laughter from all around as some-late night Radio Four comedian shouts the second half of what must have been a joke. Listen numbly to the puns as I drive through the familiar streets past people who don’t seem as anxious as me to be in bed. I find the house with the light on and the right number. The laughter is snuffed abruptly as I switch off the engine and coast to a halt. Left hand grasps visiting bag, right hand swings open the door, I pivot on to my feet and stumble into action, pyjama collar flying.

No need to ring the bell, a young woman in a négligé opens the door as I approach.

‘I’m really terribly sorry to trouble you doctor.’

‘Upstairs?’

‘He works as a chef, you see. He’s only just got home.’

I climb the stairs. The chef/husband is lying at the top of the stairs in an agonized heap. He appears to have nothing on except a blanket. His entire being seems focused on his left knee, which he is clutching with both hands as it lies flexed under him. I go straight to it and he reluctantly relinquishes his grip. Exactly like my mental picture — the great, hard lump stretching under the skin on the outside of the joint, with the peculiar dent on the front of the knee where the knee-cap ought to have been.

Trying to appear more confident than I feel, I start doing what I have been rehearsing in my mind on the way — straightening the leg is the key. I grasp the knee with one hand and the ankle with the other. I fix my eyes on the patient’s face. I tell him firmly to relax. To let the leg go loose. Not to worry if it hurts — which his face tells me it does. Monitoring his expression, I begin slowly to extend the knee. I feel the tension coming out of the patella tendon, and the kneecap slowly yielding to the pressure of my cupped hand as it begins to ride up on to the ridge of bone it will have to cross in order to return to its groove on the front of the knee.

Picture for a moment the dramatic scene. The silent, midnight struggle focused on the knee. The patient, the physician and the wife, variously attired and grouped in a powerful composition. Two, perhaps even three of the characters struggling to keep bridled an almighty scream.

But suddenly, instead of a scream… a ‘pop’!

Like magic, the patella is back in its proper place and the knee is its normal shape.

I breathe out thankfully and sit back. The patient takes a little longer to realize what has happened. He gazes incredulously at his transformed limb and gradually the tension begins to leave his body. In turn, his wife, who is bent over us, senses the relaxation and begins to straighten up — her face showing the beginnings of a sobbing laugh of relief. The patient tries out his knee and finds that it will move. I encourage him to stand up. (He is wearing underpants after all.) I tell him to walk. He walks... .

It is the sort of moment when, in an earlier age, cigarettes would have been distributed and everybody would have sat around in a state of mellow, post-ictal contemplation. However, being enlightened, I make do with sitting down on the edge of their bed and writing up the out-of-hours visiting slip. I apply a probably unnecessary but proper-looking crêpe bandage. I give advice on what to do if the knee dislocates again in the future.

‘Thank you so much, Doctor. Can’t we get you something — a cup of coffee?

‘Very kind of you but no, thank you.’

‘We’re so sorry we had to trouble you.’

‘Glad to be able to help’.

Back inside the car and the cocoon of relentless comedy from the radio. Five minutes home. Lock the car. Dog doesn’t seem to check my credentials as I climb over him on the stairs. Neither does my wife when I get into bed and snuggle up. Nice, satisfying feeling about that visit. I avoid thinking about whether there will be another call — I don’t like superstition but this is far too important a matter to leave to chance. I have left my clothes draped over the bedside chair ready for instant dressing for the same reason. Putting them away neatly is, I find, an infallible method of making the telephone ring at one o’clock in the morning.

I use my new trick for getting back to sleep. I concentrate my mind on a phrase I like from the Pié Jesu in Fauré’s Requiem. I exclude everything else ruthlessly. I sink into the music. I join in and become part of it. I am asleep.

My new trick seems to work rather well.

When I do something really trivial in surgery I often joke with the patient that it has taken years of training to perfect it. I sometimes tell children that medical students have to sit for hours in classrooms learning to say ‘Mmmm’. And there is a grain of truth in the joke. There are so many different conditions in medicine that you simply can’t be trained to deal with each of them individually. But when you encounter each one it always seems that it would have been better if you had been specifically trained in dealing with it. General practitioners are constantly meeting new situations and what they do is to apply their broad knowledge and experience to the situation and more often than not they come up with an appropriate action.

As it happens, the incident in the true story I have just related was the first and only time that I have reduced a knee cap in nearly twenty years of medical practice. I’ve reduced fingers, toes, fractured wrists, and am a wizard at pulled elbows; but I’ve never done a knee cap. I’m not sure that I’ve even seen a dislocated knee cap before, or even a picture of one. By no stretch of the imagination could I be described as an expert in the field of reducing knee caps. And yet the extraordinary thing is that I had a diagnosis and a provisional plan of action in my sleepy head within seconds of the telephone ringing.

I take no particular credit for this, it is just the way all of our minds work all the time. They create internal pictures so automatically that it just doesn’t occur to us to think that there is anything clever about the process. But in this case I happen to know that I wasn’t recognizing a picture I’d seen before, and I wasn’t following a set of instructions I’d learned in my training — the two most obvious explanations. So what was I doing?

What my subconscious must have done was allow the various facts of the case to interact with the complex store of information and experience hidden away in my mind to produce that mysterious phenomenon which we call ‘understanding’. In other words it produced a model of the situation in my mind which fitted the facts as I knew them. I then used that model — quite automatically — to work out a plan of action.

And this model was no ordinary model. From my knowledge of anatomy I could see the internal structure of the leg, complete with the displaced knee cap and the stretched tissues. I knew exactly what the ridge of bone and the empty groove down the front of the knee would be like and in a very real sense I could actually feel them. Even as I was imagining these things and trying out my solution in my model, I was taking into account the distance from the hospital, the wife’s anxiety, the pain, the baby, the possibility that I was wrong, the need to be available for another call in the middle of it all. All these things, and others no doubt that I have forgotten or was never consciously aware of, were included in my model of the situation. And all before I had put down the telephone.

The point of this little story is to show that no amount of training can prepare us for every eventuality in life and that what is needed is a broad education and a free environment in which to use our common sense — the extraordinary ability which we take for granted only because it is common to us all.