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N Am J Sports Phys Ther. 2008 May; 3(2): 110–113.
PMCID: PMC2953321

Increasing Knee Range of Motion Using a Unique Sustained Method



In order for functional and sport specific activities to occur, knee flexion and extension range of motion (ROM) is necessary. Loss of full ROM at the knee joint can be detrimental to the function of the lower extremity and treatment is needed to regain full function of ROM. Research supports the use of the sustained force to increase knee ROM. This article presents a unique method of attaining sustained force. The technique is cost effective, involves equipment already available in most physical therapy clinics, conserves time, and provides consistent force overtime without causing the therapist fatigue.


Despite the fact clinical research has been performed, a poor appreciation exists for the appropriate clinical use of sports massage.


Additional studies examining the physiological and psychological effects of sports massage are necessary in order to assist the sports physical therapist in developing and implementing clinically significant evidence based programs or treatments.

Keywords: sports massage, sports rehabilitation, sports performance, sports recovery


Knee flexion and extension range of motion (ROM) is necessary for functional and sport specific activities.1 Loss of full ROM at the knee joint can have detrimental effects on the function of the entire lower extremity.2 For example, decreased knee flexion or extension ROM has been reported following anterior cruciate ligament (ACL) reconstructions, total knee arthroplasties, arthrofibrosis of the knee, and other musculoskeletal injuries involving the knee joint.35 Loss of knee flexion has been demonstrated to cause altered gait pattern affecting the ankle and hip, limited functional squatting, and difficulty negotiating stairs and sitting.2 The loss of knee extension can cause altered gait pattern affecting the ankle and hip, inability to attain the closed packed position of the knee, and difficulty running and jumping.2

Due to these complications that can occur following the loss of knee flexion or extension, regaining full functional ROM through treatment is crucial. Research supports the use of sustained force for 10 to 45 minutes at a time to increase knee ROM.6,7 Sustained force is particularly effective for long standing joint restrictions which may not be responding to intermittent force to regain ROM.6,7

Currently, physical therapists use manual pressure or mechanical devices such as the Elite Seat® (Kneebourne Therapeutics, Noblesville, IN) to attain sustained knee flexion or extension.6,8 The challenges with manual pressure include the amount of time involved and a physical therapist is required to generate a great deal of force commonly leading to fatigue. Also, the force can be inconsistent from one session to the next. Problems with mechanical devices that produce sustained pressure include the lack of availability and the cost associated with such devices.

This article presents a unique method of attaining sustained knee flexion or extension. The technique is cost effective, involves equipment already available in most physical therapy clinics, conserves time, and provides consistent force over time without causing the therapist to fatigue.


The use of this method requires minimal equipment. The following equipment is needed: hydraulic plinth, mobilization belts, towels, pillows, goniometer, bell, and foam roll.

Knee Extension

To attain knee extension to a maximum of zero degrees, lower the plinth and place the patient supine on the plinth. A towel is placed superior to the patient's patella (on the lower shaft of the femur) and the mobilization belt is strapped around the knee and the bottom of the plinth (Figure 1). The release button of the belt is placed so that it can be reached by the patient (Figure 2), as well as a bell in case the force is not tolerated well by the patient. Once the mobilization belt is secured snugly above the patella the hydraulic plinth is raised until sufficient force is applied to the knee to cause the desired amount of knee extension. Suggested duration should begin with 1–2 minutes and progress by 5 minute increments based on the patient's tolerance to treatment. The physical therapist should carefully monitor the degree of knee extension and the patient's tolerance of the sustained extension force. Use of a goniometer is suggested to confirm that the angle of knee extension meets the therapeutic goal.

Figure 1.
Knee extension to zero degrees using a mobilization belt, hydraulic plinth, and towel.
Figure 2.
Release button of the belt is within reach of the patient.

In explaining the technique to the patient, the following information is recommended. Inform the patient that at this stage in the rehabilitation, research indicates that a sustained force is necessary to regain extension ROM. Indicate that this method will cause some discomfort, but the pain should be tolerable. Explain to the patient how long the treatment will be, and that the time of stretch wil be gradually increased over the next few days and weeks as the sustained stretch is tolerated. Let the patient know that the eventual goal is a 15 minute treatment session. Tell the patient that if the treatment becomes too painful, the release button should be pressed and the bell should be activated to indicate that treatment has been discontinued. Address any questions or concerns that the patient may have prior to commencing treatment.

To attain knee extension greater than zero degrees, use a foam roll under the patient's foot (Figure 3). With the exception of the foam roll, this method is identical to the method discussed previously, including the instructions to the patient. This technique requires more caution and careful monitoring by the physical therapist during the initial setup because of the possibility of forcing the knee beyond the physiological ROM for the patient. Therefore, once the set-up is complete, check the goniometric measurement to ensure that the knee has not exceeded the contralateral, unaffected, knee ROM.

Figure 3.
Knee extension for patient lacking full range of motion, using a mobilization belt, foam roll, hydraulic plinth, and towel.

Knee Flexion

For sustained knee flexion from approximately 10° – 120°, begin with the patient in prone with the knee in maximum obtainable active flexion. A pillow can be placed under the patient's stomach, a small towel around the ankle, and a towel around the shoulders for comfort.

Attach two mobilization belts end to end and strap one end of this double mobilization belt around the patient's ankle. Crisscross this belt after going around the ankle, and then pass the belt over the patient's shoulders and fasten them to the lower portion of the hydraulic plinth (Figure 4 and and55). Again the release button of the mobilization belt is placed within reach of the patient and the patient is given a bell in case the force is not tolerated (Figure 2). The physical therapist slowly raises the hydraulic plinth monitoring the ROM and the patient's tolerance. Once the desired degree of knee flexion is attained, a goniometer is used to check the ROM. The patient receives the same instructions as described above, replacing the word extension with flexion.

Figure 4.
Knee flexion from 10 to 120 degrees, using two mobilization belts, two towels, a hydraulic plinth. Anterior view of the belts fastened to the plinth.
Figure 5.
Knee flexion from 10 to 120 degrees, using two mobilization belts, two towels, and hydraulic plinth. Lateral view of the belts around the ankle, crisscrossed, over the shoulders, and fastened to the front of the plinth.

To attain sustained knee flexion beyond 120°, the patient position is the same as described previously. The only variation is that now only one mobilization belt is required and it is strapped under the table instead of over the patient's shoulders (Figure 6). The same precautions are taken as previously described in terms of patient instructions, monitoring patient tolerance, assuring the patient can reach the release button of the belts, provide a bell, and checking the final goniometric measurement to ensure a safe sustained ROM (Figure 2).

Figure 6.
Knee flexion greater than 120 degrees, using one mobilization belt, towel, and hydraulic plinth.


The populations that these techniques would be effective for include post-operative ACL reconstructions, total knee arthroplasties, various arthroscopic knee surgeries, patellar tendon tears following repair, mild osteoarthritic changes causing loss of ROM, and various other musculoskeletal dysfunctions causing knee ROM restrictions. These techniques are cost effective, conserve the therapist's time, make use of readily available equipment, do not cause the therapist to fatigue, allow for sustained force for a pre-determined amount of time, facilitate increasing or decreasing the angle of knee ROM, and maintain a consistent force.

Suggested precautions to ensure safety include the following: move the switch for the hydraulic table out of reach of the patient to prevent the patient from increasing the ROM without the physical therapist's consent, keep a bell and the button for the mobilization belt close to the patient in case the patient is unable to tolerate the force, and once the technique is set up, unplug the hydraulic plinth in case of a power surge or someone accidentally stepping on the hydraulic switch.

The limitations of this technique include an inability to reproduce the sustained ROM outside of the clinic, and an inability to address specific joint glides and rolls which may be causing the restriction in knee ROM. The physical therapist has to determine if the stage of healing, the diagnosis, and the patient's tolerance would warrant the use of sustained flexion or extension.

Sustained force is not appropriate for every stage of healing and can cause further inflammation, pain, or dys-function if the patient is not an appropriate candidate. However, if the physical therapist is considering using sustained force to attain knee ROM and has had a trial with manual sustained force without complications, these techniques can be used safely and effectively.


The author would like to acknowledge the contributions by Yuka Nakamura and Drew MacDonald.


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Articles from North American Journal of Sports Physical Therapy : NAJSPT are provided here courtesy of The Sports Physical Therapy Section of the American Physical Therapy Association