hyperextended finger

[lia04]

Hi everyone,
I always have students with the first joint of the finger hyperextended when playing(bend back). I mentioned so many times, but she still can hardly correct it when playing one piece. Dose anyone have some approach to help her get the correct feeling of the fingers?

Thank you so much!!
Lia

[nyiregyhazi]

Hi everyone,
I always have students with the first joint of the finger hyperextended when playing(bend back). I mentioned so many times, but she still can hardly correct it when playing one piece. Dose anyone have some approach to help her get the correct feeling of the fingers?

Thank you so much!!
Lia

In short, you need to lengthen the joint, not attempt to contract it. See my blog for a post all about it. It's currently the most  recent.

[iansinclair]

The finger (likely all of them...) needs strengthening in the curl direction.  You're not looking for a hand-crushing grip, but you do want strength.  Almost any exercise -- squeezing a ball or something of the sort -- might help, just don't have the student overdo it.

[nyiregyhazi]

The finger (likely all of them...) needs strengthening in the curl direction.  You're not looking for a hand-crushing grip, but you do want strength.  Almost any exercise -- squeezing a ball or something of the sort -- might help, just don't have the student overdo it.

sorry, but this simply doesn't work for anything but a hand that doesn't readily collapse in the first place. For one that collapses easily, attempting to curl actively contributes to causing collapse. See my blog post for very specific detail as to why this counterintuitive result is caused. If you still believe that after reading it, I'd greatly appreciate a response that details any basis for disagreement. The idea that the curling action is too weak is a dead end, as it's strength of the curling action that directly makes collapse happen. My fingers very rarely collapse. However, the only things that can cause collapse are intent at usage of the curling action or excessive downward arm pressure. Foe the curling action to work, you need to make arm pressure very slight (and even then it won't necessarily work for fingers that easily buckle). There's a very simple issue of mechanics/anatomy that, while typically missed, explains why trying to curl actively causes collapse in the opposite direction. It's all in my blog post.

[hardy_practice]

It's nothing to do with blogs or   lengthening. We are just not used to grasping with one finger.  I teach 'em to scratch the keys, but the will needs to be there - often it's not.

[dima_76557]

@ lia04

It all depends on where it comes from. There is a difference between congenital problems and improper alignment. Anton and Nicholas Rubinstein, for example, both had collapsing nail joints (can be compared to the ankles) that couldn't be fixed, but it didn't bother them. Actually, some think that their big tone was the result of this inborn quality. Others may experience pain (locally or in the underarm) when they press against a collapsed joint, and may need either re-training to find the right quality of movement, or medical help.

Generally, I think that collapsing middle joints (can be compared to the knees) in the fingers are much worse for a good technique, because those joints take much of the impact in piano playing. If they can't do that, the shock will be absorbed higher up, and pain in the wrist, etc. may be the result.

Weak knuckle bridges in the hand (can be compared to the hips) may keep them from advancing to more difficult repertoire.

P.S.: Overdoing pressure on joints and trying to "lock" them in any direction is never a good idea. What N. indicates could be at least a temporary solution. Since this is a ligament problem, not a muscle problem, "grasping" may actually worsen the problem if we think about how the collapse occurs. Personally, I would try slightly lifting the finger and swinging it lightly into the key without adding after-pressure to the joint. There is more than a good chance that nature will solve the problem itself.

[hardy_practice]

It all depends on where it comes from. Since this is a ligament problem, not a muscle problem, "grasping" may actually worsen the problem if we think about how the collapse occurs.

Dare I ask which ligament? And you need to ask yourself have you ever seen someone hyperextend when they grasp something?  Your advice raise the finger is good.

[dima_76557]

Dare I ask which ligament?

I would have to ask a specialist on anatomy. I was told that the problem was actually not a muscle problem and I never dared challenging that diagnosis. Actually, in my hands, there was never anything that did not collapse. They started me on the metacarpals (the knuckle bridge, which *can* be trained with "muscle" training), and then went down to the proximal interphalangeal joints (the "knees"). I remember wearing funny things on my fingers to keep everything together. The distals (nail joints) took care of themselves with time.

[hardy_practice]

Then I think you must mean tendons, but one end of them is connected to muscle.

[dima_76557]

Then I think you must mean tendons, but one end of them is connected to muscle.

No, no, the word was "svyazki" (ligaments), not "sukhozhiliya" (tendons).

[hardy_practice]

Well, the only ligament problem I know of in the hand is trigger finger and it's not that so I don't really know what you mean.  Basically the nail joint breaks because the longest finger tendon isn't pulled by the muscle in the arm.  But it's a brain thing - the movement has been incorrectly conceptualized.

[dima_76557]

so I don't really know what you mean.

I don't know exactly. Specialists distinguish between hyperextension and hypermobility, but I've never given the subject enough thought to be able to give you a correct answer.

[hardy_practice]

The problem's not congenital for the vast majority just the wrong learned coordination.

[nyiregyhazi]

It's nothing to do with blogs or  lengthening. We are just not used to grasping with one finger.  I teach 'em to scratch the keys, but the will needs to be there - often it's not.

quite- blame the students lack of "will" to perform an action that absolutely anyone is capable of doing in the air with tremendous ease. Don't blame yourself for giving instructions for an intent that no longer has the same effect when that finger is to be applied to a piano key.

If you bother to read the blog post, you learn the simple objective reason why trying to perform the action that is so easy in the air CAUSES the finger to buckle at the piano (unless the student has the advantage of very strong ligaments). Specifically it's because trying to close the fingertip also pulls back at that joint via the stronger pull from the middle joint. What we are not used to is lengthening the finger out. Alternatively, keep blaming your students for not having the "will" whilst giving them an actively counterproductive instruction.

[nyiregyhazi]

Dare I ask which ligament? And you need to ask yourself have you ever seen someone hyperextend when they grasp something?  Your advice raise the finger is good.

when we grasp something in normal life, we do not have to join the fingertip to the key. In pianism we do. Students with collapsing joints are not imbeciles who are too stupid to intend the same simple action that their fingers have done thousands of times over. The issue is that attempting the same action fails to work, due to the difference in the mechanics of contacting a piano key, unless the ligaments are strong enough. Once again, the reason why the vital and game changing difference exists is explained in my blog post. Rather than keep raising obsolete points that are refuted in full within that post, would you care to actually read it and then voice any grounds for disagreement in direct and informed response- preferably after trying it on students with difficulties? Some of your students might perhaps appreciate an alternative approach to your telling them that they don't have enough will, no?

[hardy_practice]

Which ligaments?

[nyiregyhazi]

The problem's not congenital for the vast majority just the wrong learned coordination.

This horrific ignorance (if made in relation to talk of pulling back) can be disproved as simply as by getting a few pianist to TRY to collapse their fingers. It takes phenomenal force for me to collapse my second finger back even slightly. Even when I actively intend to cause it, the ligaments do not allow the motion. I have students where the faintest touch doubles their finger into a position that I could not even access. This is a congenital difference. Such students can indeed learn a different coordination, but hoping to get it from scratching is a dead end. Such students do not have the level of support in their ligaments. They'll stop getting the coordination wrong, when they stop attempting to curl up their fingers.

[nyiregyhazi]

Which ligaments?

Those that stabilise the joint in question. Is that genuinely hard to deduce? If this is just you trying to build up the chance to impress nobody by reciting Latin names that have no practical significance, in an unremarkable display of rote learning, then have a sarcastic round of applause in advance.

[dima_76557]

Which ligaments?

Please read here: Volar or palmar plate.

In the human hand, palmar or volar plates (also referred to as palmar or volar ligaments) are found in the metacarpophalangeal (MCP) and interphalangeal (IP) joints where they reinforce the joint capsules, enhance joint stability, and limit hyperextension. The plates of the MCP and IP joints are structurally and functionally similar, except that in the MCP joints they are interconnected by a deep transverse ligament. In the MCP joints, they also indirectly provide stability to the longitudinal palmar arches of the hand. The volar plate of the thumb MCP joint has a transverse longitudinal rectangular shape, shorter than those in the fingers.

[hardy_practice]

Please read here: Volar or palmar plate.

Thankyou for the reference - now we know what we're talking about.  I'm sure the vast majority have perfectly adequate palmer/volar plates but I would guess in well drilled pianists they are more resistant.  That really doesn't answer the OP's question on the breaking in of the nail joint problem for your average healthy student though.  The ligaments shouldn't require 'workouts' in beginners.

[nyiregyhazi]

Thankyou for the reference - now we know what we're talking about.  I'm sure the vast majority have perfectly adequate palmer/volar plates but I would guess in well drilled pianists they are more resistant.  That really doesn't answer the OP's question on the breaking in of the nail joint problem for your average healthy student though.  The ligaments shouldn't require 'workouts' in beginners.

What ligaments could we ever have been talking about other than those that govern the joint that the topic is about? Ligaments in the elbow? Nobody said that naming them would answer the question. You are the only person who implied a shred of relevance to the external terminology. However, the source posted clarifies that ligaments indeed serve to prevent hyperextension and that their level of strength is thus a relevant issue to each individual's personal ease.


Falsely portraying ligaments are if they are either merely healthy or defective misses the point. There's a sliding scale of strength. It's very common for young fingers to be too weak to balance when gripping in the tip- not a thing that would be grossly medically abnormal. When a ligament is not strong enough, any gripping from the middle joint of the finger contributes to dragging the fingertip joint back into collapse. Conversely, lengthening the same joint aims the force OVER the fingertip in a path that cannot make it buckle. A great starter exercise is to begin with the nail joint down and push yourself away. Collapse is impossible, as long as the force always aim forward and over the fingertip joint and never switches to tugging it backwards.

you're right that any finger can find the right coordination. However, when attempting to achieve balance specifically via fingertip grip, it's extremely normal for the ligaments to be too weak for this intent to work. The only style of action that can reliably result in balance of a joint that easily into hyperextension is the lengthening one. The least you can do is try it, before simply reciting dogma (and worst of all, passing the blame for any failures on to students supposedly lacking the "will" to follow instructions that would be perfectly simple, were they actually suitable for joints that are inherently most prone to hyperextension).

[hardy_practice]

Deary me, thou doth protest a lot!  I think I'll wait till you've calmed down.

[ben_crosland]

@nyiregyhazi - I read your blog post, and found it interesting.

However, when I experimented with my own fingers, I encountered a phenomenon which may interest you:

If I pull my finger back along a surface as though scratching or gouging, the nail joint remains curved outward. However, if I do it as though wiping or smearing, the nail joint collapses.

The two gestures, when performed in mid-air, are indistinguishable.

Could it be that students who are prone to joint collapse are simply inclined to pull the wrong muscle group instinctively, and therefore need more specific instruction?

[hardy_practice]

Interesting observation.  I tell my students to make sure the their nail comes in contact with the key.  I can see how 'wipe' could cause the opposite.  It's all in the psychology.

[nyiregyhazi]

@nyiregyhazi - I read your blog post, and found it interesting.

However, when I experimented with my own fingers, I encountered a phenomenon which may interest you:

If I pull my finger back along a surface as though scratching or gouging, the nail joint remains curved outward. However, if I do it as though wiping or smearing, the nail joint collapses.

The two gestures, when performed in mid-air, are indistinguishable.

Could it be that students who are prone to joint collapse are simply inclined to pull the wrong muscle group instinctively, and therefore need more specific instruction?

In many cases it's far from impossible for this work, agreed. However, some students have fingers that hyperextend in response to such small forces, that I'm skeptical as to whether any intent at curling up during the key depression is even possible as a solution for them. Anyone can learn to scratch softly once the key is already depressed without collapse (if they're very careful and very gentle). But once you have a key to depress with a healthy intensity, some hands are just not suited to that manner of action at all. The only reliable trick is to have already done your curling first and actively uncurl to move the key - as nothing about the action can inherently promote collapse.

Also, my chief reason for disliking this movement as the norm, (even when the student has collapse issues) is detailed after the initial section on hyperextension. It causes muscular conflict in the hand (even in low intensity sound production) and makes everything close in rather than expand between fingers. When i used to use those kinds of gripping movements, I used to get joint pains in the tips and I had pathetic spacing between fingers for my large hand. I've not had this type of pain since I changed style of movement and I also have obtained a comfortable octave stretch between 2 and 5. The collapse issue is just the tip of the iceberg when it comes to the danger of making the scratch action part of the standard pianistic approach.

[hardy_practice]

When i used to use those kinds of gripping movements, I also used to get joint pains in the tips. I've not had this once since I changed style of movement.

Never had that, even at loud volumes.

[nyiregyhazi]

Never had that, even at loud volumes.

I've never seen any evidence of you playing loud demanding repertoire, on your youtube account. At the time when this sometimes caused issues, I was playing various big Liszt works, including the Sonata. I still am now, but never with even a mild ache in those joints.

Regardless, the issue of how the scratching action closes and makes the hand smaller is the primary issue of relevance to average students.

[awesom_o]

What is this argument about? Must we really argue about the movements that we use to play the piano? It's such a subjective experience!

This is why Liszt refused to talk about this stuff and said 'Do your dirty linen at home'

[dima_76557]

What is this argument about? Must we really argue about the movements that we use to play the piano? It's such a subjective experience!

This is why Liszt refused to talk about this stuff and said 'Do your dirty linen at home'

Hyperextension *can* be a real problem if a person wants to advance to higher levels, because he/she loses approximately half of his/her flexor capability. The reaction to this, experienced as a "lack of strength", may become clawing and clenching into the keys, and a prolonged visit to the physiotherapist.

[hardy_practice]

At the time when this sometimes caused issues, I was playing various big Liszt works, including the Sonata. I still am now, but never with even a mild ache in those joints.  

Always 'the big Liszt works'!  I am coming over to the conclusion that this obsession with producing virtuosos helps no one.  A lighter, tensionless technique can easily be modified to some 'big Liszt' one but not the other way round.  I don't teach kids to play big works on some big concert Steinway, I teach them to play intimately and that, in my book,  is what playing is all about.  If concert pianism becomes their thing I'll happily send them elsewhere.  For hundreds of years that was after all what it was all about.  First we need to ask ourselves what's the purpose of piano instruction - too many have got it wrong, I can't help thinking.

[hardy_practice]

Hyperextension *can be a real problem if a person wants to advance to higher levels, because he/she loses approximately half of his/her flexor capability.

Funny, that's exactly what I say to my students!

[nyiregyhazi]

Always 'the big Liszt works'!  I am coming over to the conclusion that this obsession with producing virtuosos helps no one.  A lighter, tensionless technique can easily be modified to some 'big Liszt' one but not the other way round.  I don't teach kids to play big works on some big concert Steinway, I teach them to play intimately and that, in my book,  is what playing is all about.  If concert pianism becomes their thing I'll happily send them elsewhere.  For hundreds of years that was after all what it was all about.  First we need to ask ourselves what's the purpose of piano instruction - too many have got it wrong, I can't help thinking.

the fallacious implication being that the likes of Horowitz, volodos and cziffra etc. could not play intimately? Correctly taught technique closes no doors. That which works efficiently and without strain in big repertoire works in anything. It's the ultimate test of whether you get the basics right. That which works gets you by in an "intimate" setting may not necessarily apply elsewhere (particularly if intimate really means a small and bland dynamic range rather than the beautifully differentiated dynamic shadings of the kind that you'd expect from the likes of cherkassky). It's extremely easy to scrape by off the fact that the technical demands aren't great enough to expose the potential harm of a flawed style of movement.

PS. I have no idea what might be"intimate" about scraping the fingers across the surfaces of every single key. If you do this for anything other than ends of phrases, you completely crucify any hope of beautiful cantabile. A beautiful resonant tone comes primarily from joining with the keys - not skidding about over the surface, in a way that would cause extreme tension upon any attempt to play even moderately fast and loud.

[nyiregyhazi]

Hyperextension *can* be a real problem if a person wants to advance to higher levels, because he/she loses approximately half of his/her flexor capability. The reaction to this, experienced as a "lack of strength", may become clawing and clenching into the keys, and a prolonged visit to the physiotherapist.

given that the surest fix is to stop trying scratch from the tip and instead allow it to extend, I couldn't share this explanation regarding flexor capability. I don't think the flexors at the tip ate inherently important in the majority of playing However, it can certainly be physically dangerous and it also introduces an element of chaos into the situation. Abrupt collapses make the resulting tone unpredictable and make it necessary to clench harder in order to stay poised. All of this is almost always negative. The one exception id give is when you've already collapsed before starting to move the key in big chords. This isn't necessarily bad, as it brings less uncertainty into the result than a violent buckling in middle of a fast run. It still takes the ligaments to their limits though.

[hardy_practice]

the fallacious implication being that the likes of Horowitz, volodos and cziffra etc. could not play intimately?

Is it?

[hardy_practice]

That which works gets you by in an "intimate" setting may not necessarily apply elsewhere

Just what they said of Chopin.

[nyiregyhazi]

Just what they said of Chopin.

Chopin executed advanced technical demands at fast tempos. He doesn't work as a supposed example of the idea that you should stay in a small personal comfort zone and never test the effectiveness of your approach on serious difficulties. A technique that needs to be protected from fast double octaves etc (which even Chopin used) is not a good foundation. It's an improperly tested and self limiting foundation. At high speeds, the fingertip pull is a source of tension and limitations. It's not a teacher's place to decide that his level of attainment is the highest necessary goal and that no student need learn things that might enable them to go beyond it, without causing harm.

[hardy_practice]

Chopin executed advanced technical demands at fast tempos.

And at greatly attenuated dynamics on very light touch pianos.

[dima_76557]

I am coming over to the conclusion that this obsession with producing virtuosos helps no one.  

I don't think this has to do with the wish to produce virtuosos per se. I think teachers want to give students potential for growth, give them the right technical tools, so that when they are on their own, they will be able to pass the ultimate test of a couple of virtuoso pieces if they want to without getting hurt. Besides, not everything in the virtuoso literature is loud and fast. Liszt's transcription of Schubert's Ave Maria, Godowsky's transcription of Saint-Saëns' "the Swan", etc. are very intimate, but what a superb technique they require to express the musical content to the listener, suggesting simplicity! All those layers of sound require perfect control over tone and body, qualities that will give them more musical maturity in the classics.

[outin]

Amusing to read this thread after spending almost half my lesson yesterday trying to come up with exercises to fix the hyperextension in my right 5th. It is a real impairment, because it prevents me from playing a proper octave. The 1st joint just gives away while I cannot straighten the 2nd. I think it's a bit similar to the problem on the right thumb. Trying to curl causes the finger to snap or the tip to slide under. Trying to extend causes the tip to slide to a badly hyperextended position which is painful. In general the fingertip can take no weight when the finger is straight. On smaller stretches I can keep the finger in some sort of shape without the knuckle collapsing, but with the octave it won't work. Using my other hand to stabilise the joints gives me a feeling what it should be like, but I cannot reproduce that.

I've been trying to "mimic" the actions on my left hand which has always worked just fine, but the finger joints on the right are just so different. Exercises I have found in books has never helped. So we'll just keep trying to find a solution...

[hardy_practice]

, give them the right technical tools, so that when they are on their own, they will be able to pass the ultimate test of a couple of virtuoso pieces if they want to without getting hurt.

You can't just play 'a couple of virtuoso pieces'.  Virtuosity is a whole new level of skill set, and I question its relevance to the vast majority.  A virtuoso piece is a display of virtuosity, the virtuosity must come first - otherwise we're just talking Sunday drivers.  To how many on this forum would it be relevant?  I could hazard a guess.

Outin, have really tried to scratch with your finger nail?  There must not be any push or poke element - analyse what scratching really entails.  Stick a tiny sticker on a key - can you scratch it off?

[dima_76557]

You can't just play 'a couple of virtuoso pieces'.  Virtuosity is a whole new level of skill set, and I question its relevance to the vast majority.  A virtuoso piece is a display of virtuosity, the virtuosity must come first - otherwise we're just talking Sunday drivers.  To how many on this forum would it be relevant?  I could hazard a guess.

Hmm. I may be mistaken, but to me it seems as if the principles of movement are the same for all levels (the foundation being a simple movement from the hand knuckle), only the further you get, the more efficient you have to be because stress elements increase. What may work in easier repertoire clearly won't work so easily anymore in more advanced repertoire (the ratio of good/bad habits and success/failure changes drastically). That's why many teachers make such a point of doing everything as correctly and efficiently as possible at beginner's stages.
P.S.: "Musicians' Health" gives a good list overview of examples of repertoire in an ascending order of stress from 1-17: https://www.musicianshealth.com/Pianostress.html
(Scroll down to "Categories of technique")

[hardy_practice]

Thanks - you provide such interesting links.  All I'm saying is lets just be concerned with the stress level (and I think Beauchamps puts that across well) where we're at.  As long as a student's technique is relaxed they can supplement it as the stress levels rise.  

 

[outin]

Outin, have really tried to scratch with your finger nail?  There must not be any push or poke element - analyse what scratching really entails.  Stick a tiny sticker on a key - can you scratch it off?

Yes, I can scratch keys. But that does not help with the octave because my palm is not nearly wide enough to reach an octave without extending a straight 5th as far as it goes. Keeping the 2nd joint straight enough to reach while not letting the tip overextend is only possible with pressing the tip strongly to the key to help... which is not possible while actually playing an octave. A broken octave is not a problem because I can use the next key to strech my thumb more open. This is not simple to explain in words...

[hardy_practice]

. This is not simple to explain in words...

quite!  I wouldn't give up looking for a solution though.

[nyiregyhazi]

Amusing to read this thread after spending almost half my lesson yesterday trying to come up with exercises to fix the hyperextension in my right 5th. It is a real impairment, because it prevents me from playing a proper octave. The 1st joint just gives away while I cannot straighten the 2nd. I think it's a bit similar to the problem on the right thumb. Trying to curl causes the finger to snap or the tip to slide under. Trying to extend causes the tip to slide to a badly hyperextended position which is painful. In general the fingertip can take no weight when the finger is straight. On smaller stretches I can keep the finger in some sort of shape without the knuckle collapsing, but with the octave it won't work. Using my other hand to stabilise the joints gives me a feeling what it should be like, but I cannot reproduce that.

I've been trying to "mimic" the actions on my left hand which has always worked just fine, but the finger joints on the right are just so different. Exercises I have found in books has never helped. So we'll just keep trying to find a solution...

if you literally slide forwards in the extending action, there's a danger that the joint can collapse still- particularly if you have a habit of downward arm pressure (which is almost always an issue when fingers are collapsing). Start resting flatly down on the nail (by curling up first) and gently push yourself back away from it until you're in a pianistic posture with no sliding during extension. The extending  should feel slightly forwards but not be making you slip, or its too much force. I've never yet found a student who couldn't get it from this starter point, although it can still take a lot of perseverance to make this action habitual in playing.

[nyiregyhazi]

And at greatly attenuated dynamics on very light touch pianos.

I don't care how attenuated the dynamics of a TB sufferer were. Are you suffering serious illness? Chopin could still play for real and many commented on the fire he cold achieve. Once you're seriously trying Chopin etudes at speed on even a light action piano, you'll be in a position to say whether the scratch is working for you or limiting you. The only real test of a movement is whether it causes tension at higher speeds or not. Any idiot can bob their arm/scrape their fingertips/whatever else on every note of flight of the bumblebee with perfect comfort if they go slow, yet be clueless as to the more specific quality of movement that is needed to even approach a performance speed. Chopin is not evidence that you need not aspire to a technique that is versatile enough to pass the test of basic pianistic demands. Even if you're not a virtuoso, a pianist who never attempts to execute articulated scales at fast speeds (yet who claims to take piano seriously) is simply hiding from their incapability and self-imposing limitation. Chopin never did that. He kept exploring the limits of possibility.

[hardy_practice]

I don't care how attenuated the dynamics of a TB sufferer were. Are you suffering serious illness? Chopin could still play for real and many commented on the fire he cold achieve.

That's a very interesting comment.  I've played on a Broadwood grand of Chopin's period and the first thing that comes to mind is what fire is at one's fingertips.  I've played a Fazioli on the other hand - it plays itself, but no fire.

[awesom_o]

Today's pianos are so massive that they can swallow up whatever fire we throw into them.

We have to be the fire itself, though. It is possible.

I'm very interested in recording the Beethoven Sonatas on a period instrument. I'm glad I went modern for the Chopin Etudes, though.

It is very difficult to play using Chopin's technique on a modern instrument. Not impossible, but extremely difficult. You definitely need to be a virtuoso of the highest caliber.

[nyiregyhazi]

That's a very interesting comment.  I've played on a Broadwood grand of Chopin's period and the first thing that comes to mind is what fire is at one's fingertips.  I've played a Fazioli on the other hand - it plays itself, but no fire.

if the fire were owing to the instrument, it's a little strange that experienced musicians still commented on it, no? Chopin produced it- by not taking the ridiculous mindset that he should stay in his immediate comfort zone and never seek a quality of technique that works for a range of speeds and intensities.

[outin]

if you literally slide forwards in the extending action, there's a danger that the joint can collapse still- particularly if you have a habit of downward arm pressure (which is almost always an issue when fingers are collapsing). Start resting flatly down on the nail (by curling up first) and gently push yourself back away from it until you're in a pianistic posture with no sliding during extension. The extending  should feel slightly forwards but not be making you slip, or its too much force. I've never yet found a student who couldn't get it from this starter point, although it can still take a lot of perseverance to make this action habitual in playing.

I don't think you understood the problem completely here...I can prevent the 5th from collapsing in normal playing by avoiding too much pressure. It's the octave that is the real problem.

I've done that kind of exercise before though and I think it was useful in learning to control the finger. But it didn't help to compensate enough for the joint issue.