Continuous Passive Motion

Everything there is to know about a Continuous Passive Motion Machine

Continuous Passive Motion machines are tools used mostly to rehabilitate a whole limb or any exact part of it (joint, muscle, ligament, bone, etc.). It works pretty much adequately on both an arm and a leg with no observable difference. They are useful following various dangerous surgeries on the joints, massive trauma, neurological pathologies, and prolonged unconsciousness states. 

An enormous number of diverse medical practitioners have an incredibly high opinion of these instruments. Nowadays, almost every patient who stayed at the stationary treatment for more than three weeks needs to get at least a 3 - 4 days course of rehabilitation procedures using that apparatus.

A little bit of a CPM machine history

Throughout medical science history, various general medical practitioners, philosophers, scientists, and physiotherapists made different queues about the benefits that can potentially grant passive movements to damaged limbs. As a result, medical practitioners began to use their own hands to move their patients' arms and legs when they need rehabilitation.

But it is an uneasy job to make such movements during the whole session of rehabilitation only by hands. For this reason, after 18 years of steady work in 1970 by M. D. Robert B. Salter creates a fundamental concept of CMP apparatuses. Yet, it was far from making the first physically existing CPM machine.

Salter suffered from a lack of engineering knowledge and skills, so he sought the help of an American engineering community. John Saringer, a Canadian engineer, decided to help Robert, as he highly valued the idea. After eight years of hard struggle, in 1978, they finally created the first CPM machine in the history of humankind.

Indications to use a CPM machine

The first and the leading group of indications to use those types of apparatuses are different traumatic injuries of the limbs, the arms, and legs. There is also a tool for rehabilitation of injured fingers. With this, CPM machines are useful almost exclusively during stationary treatment of patients, as they usually are unable to walk correctly or need any additional care. Typically, this type of rehabilitation ends with the best possible prognosis for the patients.

The second major group of indications is the nerve system's different pathologies accompanied by muscular dystrophy processes or partial breach of innervation. In these cases, CPM machines usually cannot cure the pathology and rehabilitate the human to a fully healthy state. They are most used in practice to stop the fast progress of those diseases. Unfortunately, most often, those groups of pathologies can't be adequately treated at all. Here are the most noticeable of them:

  • amyotrophic lateral sclerosis
  • degenerative diseases of the central nervous system
  • dystrophy of the distal parts of the nerve system
  • degeneration of the distal branches of the nerve system
  • mechanical brakes of various nerves
  • pathologies, accompanied by demyelination of nerve fiber
  • cerebral palsy

The third major group of pathologies requiring the use of these apparatuses is problems typical to older people. These pathologies have connections with processes of degeneration, aging, and trauma of different parts of the skeletomuscular system. They also may occur in young people with excessive body weight, genetic predisposition, or in persons suffering from any associated diseases. The most usual pathologies that require a CPM machine use:

  • various localized muscles dystrophy
  • incorrect fractures fusions
  • cases, accompanied by ligament shortening
  • various pathologies of cartilages
  • ankylosis of different joints 
  • various arthritis types
  • deforming arthrosis of distinct localization

It is also worth mentioning that different pathologies following prolonged unconsciousness are also very often treated with different types of those devices. These mostly connect with pronounced prolonged musculus inactivity, which leads to a dystrophic process of varying severity. Usually, the prognosis for those patients is pretty favorable.

Complications of using a CPM machine

In a normal situation, there is not even a little possibility of any difficulties occurring at all. But, it's not a simple method, and it should be performed only on medical practitioner supervision. Usually, they need to know various things about an arrangement of continuous passive motion apparatus, possible regimes of work, and signs, showing that it's time to stop the procedure. If untrained individuals utilize these devices, there is a significant chance of harm. Most commonly, these may occur from:

  • Repeated bone fracture
  • Nonunion (false joint)
  • Various mechanical trauma types
  • Traumatic arthritis
  • Bursitis
  • Ligaments break
  • Reposition of the bone pieces
  • Hypermobility of different limb parts

All these complications may also occur while using a malfunctioning tool. It often may become a reason for traumatic injury not only for the patient but also for the operator of the machine. Even the CPM machines do not show significantly increased effectiveness compared with other active methods of rehab. But physiotherapists still insist on its usage in every possible case, which seems like they do not want to work with their hands in actively patient motion.

General specifications of a CPM machine

There are a lot of different variations of CPM machines that exist nowadays. For example, the CPM machine's construction for hands will have a slightly different design of tools created for legs. And it's even hard to imagine what kind of engineering mechanism laid inside a continuous passive motion machine for the rehabilitation of every single finer. But we gathered some info and arrived at this list of specifications:

  • Operational voltage - 50hz, 220v
  • Rest time - 0 - 10 seconds
  • Weight - up to 50 kg
  • Angle control - from 0° to 120°
  • Dimension volume - W 300 mm x D 310 mm x H 150 mm
  • Hold time - 0 - 10 seconds
  • Electrical Safety Class - any, but Type B, Class 1 preferable
  • Speed - from 30° to 180° per minute
  • Reversal forces - 35 - 76 lbs.

Those parameters characterize a medium from a functional perspective device for various problems with lower limbs. If you need to understand how an apparatus for the upper arm looks, then try to split on two every category mentioned above. Equipment for fingers is still something new nowadays, so it's pretty hard to find specs for them.

Market Leaders

There are plenty of different models, manufactured by hundreds of different fabricants, available on the market nowadays. Every day, dozens of new designs of CPM machines reach the marketplaces around the whole world. It was not easy to determine who are the best manufacturers among a lot of possible variations. But, after complex market research, we found them. And they appear to be:

  • Physiomodalities Enterprises
  • Jullundur Enterprises
  • Chattanooga
  • Kinetec Maestra
  • Kinetec 6080
  • Medline
  • Sammons Preston
  • BodyMed
  • ABS
  • CPM Unit
  • Alpha Biomedix
  • Electro Healthcare Systems

There are many different cheap, ugly, but at the same time, pretty effective CPM machines from different Indian manufacturers available nowadays on the market. Unfortunately, they breakdown quickly, and it is almost impossible to make them work again. So, everything is left and thrown into the trash can.


Continuous passive motion apparatuses nowadays are widely used, especially in different rehabilitation programs after traumas, and various operative treatment processes on the limbs. However, they sometimes do not show any significant effect in the rehab of many pathological processes compared to traditional rehabilitation. But that has not stopped physiotherapists from using those methods widely.

Probably, there are still plenty of various benefits that this technology may bring to humanity. Although even many more technologically accomplished methods and techniques will, in the future, be an invention. Those systems will always be remembered and used by various medical practitioners. 

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