Why the CPM Machine Failed to Solve Knee Surgery Recovery
The Continuous Passive Motion machine (CPM) does not increase patient range of motion or strength or shorten recovery. In doesn’t help, and often hurts.
The X10 machine is not a CPM machine. It relies on entirely different mechanism. It does not hurt to use and is the only machine that builds range of motion and strength and reports the data daily so surgeons and other professionals can monitor progress.
Why the CPM machine doesn’t work is story of failed early research and technology. If you are interested continue reading.
The Great Hope of the Late 1970’s
The CPM was commercialized in 1978 by Robert Salter (MD) and John Saringer (an engineer). The original idea was to stimulate cartilage production in knees, at which the machine succeeded extremely well in rabbits but not humans. Humans knee cartilage has no blood supply and consequently cannot grow back.
Soon, the machine began being used to increase knee patients’ range of motion. Most studies, before 2005 compared the range of motion of patients who used the CPM, to patients who had only bed-rest. When that comparison was made, it looked as though the CPM had a tremendous effect. However, beginning in about 2005, the experiments on the CPM compared people who used the CPM to those who did not use the CPM, but also were not confined to their beds. The non-CPM control group could move about. When this latter comparison was made, then none of the studies, including large studies of more than 1400 patient showed that the CPM did not increase the range of motion over what people had who simply moved about. Experimentally, the results are remarkably clear, the CPM does not increase range of motion.
The result was that in one decade the CPM was the standard tool for recovering knee patients, and in the next decade, the doctors who looked up the research stopped using the device because it did not do what was claimed.
In the early 1970’s most civilian knee surgery patients had their knees in a cast for six weeks, and were largely confined to bed. The military not only did not cast injured knees, they immediately got patients up and moving. So at that point in time the research showed that some movement was superior to no movement. Salter reasoned that if some movement was better, continuous movement would be better still, and hence the invention of the CPM. Basically, the CPM flexed a patient’s leg through a prescribed arc. In order to work properly, the patient was to lay absolutely still for up to 20 hours a day. The purpose behind laying still was to preserve the alignment between the patient and machine. However, even moving a patient’s head disrupted the alignment, and to make matters worse, the machine itself moved over the surface of the bed. Even bolting the machine down did not solve the alignment problem. Because of the alignment problem patient’s legs only experienced 68% of the prescribed arc. And, most patients found the CPM painful and were not very compliant.
Surgeons who have kept abreast of the research, as a rule do not prescribe the CPM, though some will admit that they do prescribe it if patients ask for it or to appear to be doing something.
X10: Picking up where the CPM Machine left off
Today there are PMKR, Pressure Modulated Knee Rehabilitation. PMKR machines, like the X10. PMKR machines do deliver the results that were hoped for the CPM. Fast recovery. Fast return to work and life. Avoidance of complications. Beating the dangers of scar tissue development. Many thousands of patients have used PMKR and as surgeons learn about it, they quickly adopt this technology. For more about the X10 visit: What is the X10.
X10 patients are more than 20 times less likely to need an MUA, and while 28% of the typical knee replacement patients need a second MUA, we are unaware of any our 2,500 patients, who started their recovery on the X10, who have had a second MUA. Why risk it?