This one kills me (and yes, I've heard it, from prominent educators). It’s a bit like me saying: “I’ve never seen someone in my ER who was injured because their car hit an elephant, so it must be the case that if your car ran into an elephant at 60mph, you wouldn’t be injured.”It is true that, anecdotally at least, the majority of bondage nerve injuries occur due to rope around the wrists and the upper arms. While I know of several cases of injury from rope around the elbows (damaging the ulnar or radial nerves) and knees (damaging the peroneal nerve), it isn’t common. I would theorize that this is because putting load bearing rope around the knees and elbows is clearly a bad idea, most people have been counseled not to do it, and most people DON'T do it (especially people who do suspensions, where the majority of injuries occur). Just like I’ve never seen a car vs. elephant injury in my ER, you don’t see many injuries due to someone being strung up by their elbows. But that doesn’t mean that it isn’t a potentially harmful activity!
Multiple studies across decades of research have documented nerve injury due to placement of blood pressure cuffs too close to the elbow345 (there are more listed here) -- the across-the-board recommendations of these articles was to place the cuffs more proximally (away from the elbow and up on the arm). Why? Because in the elbow area, the nerves and blood vessels are close to the surface with little “padding” and are more prone to injury. In the words of one study author: “Locating the cuff higher on the arm, away from the elbow joint, to avoid the most superficial portion of radial nerve, may prevent this type of compression injury…”4 Moving on to the knee area, in the words of another author talking about the peroneal nerve at the back on the knee: “It is well established that the peroneal nerve is susceptible to injuries due to its anatomical course… Due to its superficial anatomical course around the fibular neck [at the knee], where it is covered only by skin, subcutaneous tissue and a fat pad, the nerve is susceptible to damage due to pressure against the bone…”6 Putting load bearing rope directly around the joints is very high risk, and the low number or reported incidents involving this mechanism only tell us that most people understand this fact and avoid such bondage.