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Locking and Specificity

The question posed is this; is it possible to make the force of a manipulation specific to a given segment. But more than this we should ask is it necessary to do so. It calls to question the purpose and the need for specific and axial locking in manipulation. There is debate going on about whether it is necessary to lock joints prior to manipulating or whether a regional approach to manipulation is not only simpler but adequate.

Let’s first define locking and what it accomplishes (at least what its proponents purport it accomplishes). Locking is moving the segments to their ends of range to make them stable to transmit or accept forces effectively and safely. There are many methods of locking some sensible and others less so, including ligamentous, articular, neutral, axial and so on but they are not particular relevant to this discussion.

Locking has three main purposes that I can see and a fourth that is certainly debatable:

1. It forms a rigid lever when the joint that is to be manipulated is distant from where the force is to be applied. The best example is manipulating any lumbar segment above L5/S1 when the force is applied to the innominate.
2. It protects joints above or below the target segment from the force of the manipulation.
3. It makes the force specific to the target segment

There can be little debate that locking segments does provide a more rigid lever to transmit forces than does leaving the segments unlocked. There are a few ways of dissipating forces including the production of heat and the production of movement. The first way is really not a significant factor in manipulation, the heat generated is probably un-measurable but the second is very significant. If the intervening segments move then energy is lost in making them move and less is delivered to the target segment. So to generate optimal effect the amount of force applied has to be a good deal higher than it need be if the segments are locked. But this particular issue does not impact on the debate as with regional manipulation the intervening segments are locked or the applied force couldn’t move the target segment (we can argue at a later time about which is the better way to lock but not about the fact that locking is taking place).

Does it protect the segments above and below the target segment from the applied force? Only if the locking takes into account the particular sensitivity of the segments in question. The common and accepted wisdom is “you can lock a hypermobile joint but you shouldn’t thrust through it and you cannot lock an unstable segment” The first statement may well be true, it is certainly prudent; but the second I would reject unless it is qualified. I would say that an unstable segment may not be lockable in the direction of its instability. So if a segment were unstable into extension (or more accurately posteriorly) there should be no reason why it couldn’t be locked into flexion or any other direction that does not involve a posterior shear. But the bald statement that locking protects joints and/or segments is flawed unless the direction of its sensitivity is taken into account in the locking process.

If there is one guiding principle to doing anything it should follow Einstein’s statement that “things should be as simple as possible but no simpler”. Certainly simplicity is a wonderful thing, it reduces complex issues to manageable proportions but over-simplification reduces them to the point where the simplified model no longer resembles reality.

As far as protecting joints or segments beyond the target segment (that is on the far side of the segment to the applied force) it is unlikely that locking helps very much at all and may in fact put segments at more risk than if they were left unlocked. If I want to limit how much force reaches those segment I can either very carefully adjust the amount of force applied to the point where optimally affects the target segment but not those distal to it (extremely ambitious for anybody other than a stone expert) or I can have the force dissipate. To do this the obvious thing to do is leave these segments unlocked and in neural and allow them to move. But there may be another reason to lock these segments other than protection and that is there may be a bounce back effect similar to the swing executive balls you can buy; but I really don’t know. At the moment I would say that it probably doesn’t matter much whether they are locked or not as far as protection is concerned. However, it will probably make the technique more efficient if I can move the target joint to the end of the range I want to regain by moving it to its abnormal barrier from above and below but that’s a discussion for a future date.

Now at last to deal with the question posed can we be specific with our locking techniques. There are two aspects to this question can we make the force specific to the target segment only or even maximally and can we make the lock make the manipulation produce a specific movement. I would say the first idea is patently untrue. If we are pushing on a rigid lever that force is felt throughout the lever and in fact the force will be stronger where the lever is close to the applied force than is it further away. So if we lock L5/S1, L4/5 and L3/4 to lever the force to L2/3 then these segments will feel the force more strongly than will L3/4 but they will not move if the lock is effect.

Can we move the joint in a specific direction – maybe but only if it is set up at the end of that range before the manipulation is applied. The lock must do double duty now, it must be act as a rigid lever and it must barrier the target joint at the end of its abnormal range so that the manipulation can push it into it.

Conclusion

As far as I can see it is not possible to make the force of the manipulation specific to any segment unless you are exceptionally skill and probably a bit self-deluded but by setting the lock up to barrier the target joint you may be able to move it in the desired direction.

Is regional manipulations all we need, is the simpler method as simple as is necessary or is it too simple and miss effects. The question for another time, but whatever the answer is it shouldn’t be based on belief systems or traditions but on rational and scientific arguments.

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