Improving the range of movement (ROM) of a joint is arguably one of the primary functions of a physical therapist. Physical therapists employ many techniques to improve the ROM of a patient’s joint, including stretching, active and passive exercises, and direct mobilisation and manipulation of the joint. Tai Chi also have techniques involved in achieving optimal use of the joints of the body. One of these is peng jin; in simplest terms, the ability to ‘open’ the joints to assist free flow of qi (energy) through the body. Understanding and being able to apply peng jin could assist physical therapists improve ROM in their patients.
What is ‘Normal’ Range of Movement and Why is it Important?
Normal ROM is considered to be the standard acceptable range a joint can move through in a given plane of direction given normal anatomical considerations. For example, normal active ROM for a knee is generally considered to be 0 (extended) to 140 degrees (flexed). Maintaining normal ROM of joints is essential to preserving normal functional capacity; when the joints don’t move the way they’re supposed to, we are no longer able to do the things we want to do.
Injuries, diseases, deformities, foreign bodies, and limitations of soft tissues can all restrict the ROM of a given joint, resulting in reduced function, pain, and disability. A good example of this is the reduced ROM seen in osteoarthritis of the knee. As the disease progresses, many people demonstrate reduced knee extension (ability to straighten the knee). This is often observed as a tendency for the person to stand or walk with the knee bent. This starts as response to pain and the person’s attempt to reduce weight-bearing on the joint especially when walking. In time and with progression of the disease it can produce physiological changes, such as tears or deterioration of the cartilage and abnormal surface changes to the bone resulting in decreased joint space, as well as shortening of (primarily) the hamstring tendons. It is a self-perpetuating process: the more time a person spends walking on a bent knee, the more damage and changes are done, the more the person tries not to straighten the knee because of pain.
How Can Tai Chi Help?
There have been a number of clinical studies have demonstrated that practicing Tai Chi can be beneficial in improving physical function of people with osteoarthritis (for example, see the meta-analysis published by Yan and colleagues). However, not all patients seen by physical therapists are able to integrate Tai Chi forms into their rehabilitation, especially in its earliest stages (for example, post-joint replacement therapy). There are however concepts within Tai Chi, such as peng jin, which could be utilised early within the rehabilitation process to facilitate a patient’s progress.
A simplified way of understanding peng jin is to think of it as opening the space between the joints of the body, thereby extending the limbs and trunk. In the early stages of learning, students often use mental imagery to conceptualise the opening of the joints as they practice their forms. A skilled practitioner is able to demonstrate a physical change when applying peng jin to a specific part of the body.
Consider what happens to the knee in the case of osteoarthritis, as demonstrated in an x-ray image below:
The loss of joint space in the affected knee results in a decrease in ROM, both from the narrowing of the joint space, and the subsequent pain resulting from bone-on-bone contact. If the principle of peng jin is to ‘open’ the joint – effectively open the joint space – then it stands to reason that the application of peng jin could result in increasing the joint space, thereby relieving both the physical restriction and pain-producing factors which limit ROM.
Applying Tai Chi to Physical Therapy: Recovery from Joint Replacement Surgery
A common acute limitation to ROM after total knee replacement surgery is the inability to fully extend the knee. Improving extension range in the acute phase of rehabilitation can be challenging, as the patient is often limited by pain and swelling, as well as being preconditioned to not fully extend the knee. Improving extension ROM at this stage often comprises passive and gentle active techniques as more aggressive techniques – for example, manual therapy techniques – are contraindicated while the patient recovers from surgery.
One such past patient of mine had considerable difficulty improving their range of knee extension post-surgery. Using traditional physical therapy techniques, over ten days the patient was able to demonstrate an improvement in knee extension from -10 degrees to -4 degrees extension (the negative indicating the shortfall from a neutral 0 degrees position). However, despite rigorous adherence to their home exercise program and employment of available techniques during appointments, the patient seemed unable to make further progress beyond -4 degrees.
Based on the principle of peng jin, I taught the patient a visualisation technique of ‘opening the joint’ and ‘extending the limb’ while performing a seated knee extension exercise. Within four repetitions the patient demonstrated improved extension range, and by the completion of ten repetitions was able to demonstrate 0 degrees (neutral) knee extension. At the next appointment the patient demonstrated that they had maintained some improvement, measured at -2 degrees knee extension, and by the following appointment demonstrated consistent ability to achieve 0 degrees extension in all positions.
Again, this is at best observational evidence of a specific application of Tai Chi principles to physical therapy. However, it does support the increasing body of evidence-based research advocating Tai Chi as a means of improving function and mobility, and in my opinion, is worth further investigation as an adjunct to physical therapy.