There has been a lot of discussion on this topic and it’s wondered far and wide around the subject and has largely been based on personal preferences, anecdotal ‘evidence’ and ‘people said to me’ kinds of things.
To an extent people have been putting the TK on trial rather than the knowledge, safety information and skills required for it’s safe use. I wonder however if “Is the TK safe” the right question.
If you want to ask this kind of question it helps to know what the question really is.
Do you mean in an absolute sense? If that’s the question then the answer is easy; no, nothing is safe in an absolute sense and therefore a TK isn’t safe either.
Do you mean to suspend someone in one position for extended periods? If so what constitutes and extended period. What’s the weight distribution on the body? How else is the body to be supported? What position would the suspension be in?
If you want to compare it to other ties then are they comparable? Do they provide equivalent restriction, can you do similar suspensions and transitions?
Another thing I’d consider a key question is, what’s a TK anyway? You can simplistically say that it’s a box tie, that rope goes over the arms etc. But there are so many different variants and methods of construction that it’s very hard to agree exactly what a TK is. And if you don’t agree this before discussing it’s safety then you invalidate the discussion by talking at cross purposes at anything but the most general level.
A big problem with this kind of question is evidence. We know that there are injuries, we know that many variables effect what these injuries are and their severity. What we don’t know is how significant each of these factors are. Without a serious scientific study this is going to continue to be a problem for any discussion. Things like “I’ve never had a problem with”, “Nobody I’ve talked to has” and the like aren’t really helpful or significant. I’ve never been run over crossing the street, this doesn’t mean that people aren’t run down crossing the street or that there isn’t a level of danger associated with crossing the street. If someone says to me that they’ve never known someone who was run over crossing the street does that in any way effect the likelihood of it actually happening? Of course not. Anecdotal evidence is for reasons such as that almost totally meaningless. Individual experiences are unavoidably subjective. Given enough accurate information it’s possible to build up a more informative picture. The more information that is recorded and the greater number of incidents the more a real picture will emerge. However it must be born in mind that this reporting is itself subjective and not scientific observation.
So, where does that leave us? Not anywhere in particular, don’t get the impression that the information gathered as described above is useless. It does at the very least inform us of the trend of the most common problem and their type. Or to be absolutely clear about this, the most commonly reported problems and their type. What it doesn’t accurately do is inform us of the exact cause though we can make some deductions, without testing however we can’t guarantee that our deductions aren’t skewed by factors that we’re not aware of.
From all the forgoing we know that injuries of concern are nerve injuries, we know that people have suffered wrist drop, palsies and the like. From this it seems fair to deduce that these injuries are caused by the pressure of the rope over the nerve.
Let’s assume for the sake of argument that placement is the key to these injuries and avoiding them. If we make that assumption what if any other factors come into play? Is there any way we can justify that proposition?
Hypothetical case 1
Let’s consider the same tie with the same tension and the same placement and the same model, once on the floor with no suspension pressures and once in suspension. In our hypothetical case the suspension results in nerve damage and the floor bondage doesn’t.
This, given the relative incidence of nerve damage in suspension vs. floor bondage seems a case that is likely to occur and very probably has on a number of occasions or at least a very close approximation. In this case as the placement is the same in both instances it must be that some other factor has come into play. What could this be? The obvious one is that the amount of pressure applied to the body is much greater in suspension than in floor bondage. So pressure is a factor.
Before we go further let’s have another hypothetical case.
Hypothetical case 2
Let’s consider the same tie as in case 1 but with a slightly altered rope placement, with the same model the same suspension.
This time their is no injury. Given that the pressure applied to the body is the same as in case one we can only assume that the rope placement made the difference.
So we can now assume that rope placement is not the sole cause, pressure is not the sole cause, we need bad rope placement plus pressure. We can however further deduce that rope placement is the primary causative factor but does not necessarily result in injury without a certain amount of pressure.
If we accept that placement is the primary cause then the other factors that may come into play will be regarding the extent of possible damage, for instance muscle tone, weight, body fat, rope thickness, time under stress and so on and so forth. Depending on their quantities/proportions any of these factors may be positive or negative influences but in cases where any of these mitigate the effects of pressure it is the case that they only mitigate and not prevent.
(On a side note that I while I feel it’s worth mentioning but don’t wish to introduce as a complication to these examples is the fact that angle of pull/suspension can effect where a tie transmits force into the body of the tied and that this should be born in mind and accounted for with regard to dynamic suspensions and transitions)
So what conclusions can we draw?
That rope placement is causative of nerve damage injury, that it’s likely that no other factors will mitigate against this causing an injury if get it exactly wrong though they may effect the extent of the injury. If you get it slightly wrong i.e. you’re close to but not actually over the nerve then factors like body fat between the rope and the site, muscle mass between the rope and the site, force being applied via the bondage, duration of compression etc. will come more into play.
A conclusion that we can draw, is that in all cases rope placement is the deciding factor in injury. If the rope were not over or near the site of the vulnerability then there wouldn’t be a nerve injury.
What then can we do to prevent these nerve injuries? They do happen and will probably continue to happen. Sometimes because people don’t even know there is a problem to be avoided, sometimes because people don’t know how to avoid the problem, and sometimes, hard though it may be to accept, accidents happen. It’s clear however that accidents happen far less often to the more skilled.
Good information, good teaching, good attitude and good practice all help to cut down the incidence of these injuries. That being said, it is generally true that rope play, especially rope suspension play is edge play and is a danger entered into deliberately. It’s therefore incumbent on those participating to arm themselves with the best knowledge possible. This is the difference between entering into a known risk in a calculated rather than a reckless fashion.