What it's about
The precise alignment of the knee pivot point is crucial to avoid shear forces.
The knee pivot point and anatomical joint pivot point must match exactly.
Extension and flexion are individually limited using two separate rotary knobs.
A cloth should always be placed between the leg and the support, even if it is omitted in promotional material.
The correct setup of the ARTROMOT K1 knee CPM device (Kinetec) is crucial for safe and effective CPM therapy after knee surgery. These instructions are intended for specialist staff who provide patients with the device at home or in a clinical setting, and they accompany the official video tutorial from WINTER Medizintechnik with a structured step-by-step overview.
The following video provides a complete overview of all setup steps and serves as a visual supplement to these written instructions:
Step 1: Preparation and measurement (0:00 – 1:10)
Before the device is applied to the patient, both the patient positioning and the basic settings of the device must be prepared. This step lays the foundation for all subsequent settings and should be carried out carefully.
Patient positioning
Position the patient on a surface that is not too soft. Therapy with the ARTROMOT K1 should always be performed while lying down. A surface that is too soft can distort the device setup and impair therapy success, because the device does not rest correctly against the leg and the movement axis cannot be aligned precisely.
Measure thigh length
Measure the length of the thigh between the greater trochanter and the center of the knee. Carefully note the measured value, as it is entered directly into the thigh scale setting on the device. An inaccurate measurement inevitably leads to incorrect axis alignment between the knee joint and the device.
Prepare the device
Prepare the device in the following order:
Connect the power cable to the device and to the wall socket.
Turn on the main switch.
Let the device run to the setup position (in the rear area of the front blue plastic cover).
Set the previously measured thigh length value on the thigh scale.
Move the device into full extension at approx. 0°.
For the time being, select a speed of about 35%. This moderate setting makes it easier to position the patient’s leg later.
Position the foot shell
Correct presetting of the foot shell is important so that the patient’s leg can later be inserted without difficulty. Proceed as follows:
Place the foot shell in the upright position.
Pretension the foot shell slightly.
First slide the lower leg length to the maximum.
Do not yet tighten the screws.
Note: The screws for the lower leg length are only tightened after the patient’s leg has been positioned correctly. Tightening them too early prevents the necessary adjustment in step 2.
Step 2: Setup on the patient (1:11 – 2:38)
In this step, the patient’s leg is placed in the device and all relevant settings are individually adjusted to the patient. Correct execution of this step is largely responsible for the success of the therapy.
Position the leg
Place the patient’s leg on the leg supports so that the center of the knee lies exactly between the two knee pivot points of the device. Initially keep the lower leg raised and slide the foot section toward the heel. The two screws can then be tightened.
Adjust the leg shells
Adjust the height of the leg shells, both on the lower leg and on the thigh, so that the supports have only light contact with the leg. The leg should rest without pressure. Make sure that the lower leg and thigh are parallel to the two side tubes of the leg support attachment. This parallel alignment is an important prerequisite for correct movement guidance.
Set the range of motion
The range of motion is set using two rotary knobs. The following table provides an overview of the function of the respective controls:
Setting | Control | Function |
|---|---|---|
Maximum extension (extension) | Upper left rotary knob | Limits maximum pain-free extension |
Maximum flexion (flexion) | Upper right rotary knob | Limits maximum pain-free flexion |
When setting the range of motion, proceed in this order:
Use the upper left knob to limit the maximum pain-free extension.
Switch on the device and let it run to the maximum pain-free flexion of the patient’s leg.
Then use the upper right rotary knob to limit the maximum flexion.
Special case: Limited extension
If the patient cannot yet fully straighten the leg, an adapted procedure is required:
Let the device run far enough into flexion so that, at the maximum possible pain-free extension, the lower leg and thigh are parallel to the rods.
If necessary, adjust the height of the lower leg and thigh shells so that the leg rests without pressure even in this position.
Hygiene note: For demonstration purposes, the video does not use a cover on the leg supports. In practice, a cloth should always be placed on the leg supports before the patient’s leg is inserted.
Step 3: Check the setup (2:39 – 3:18)
Checking the device setup is an essential quality assurance step. It can effectively only be performed at a higher degree of flexion, ideally at 90° flexion.
Tip: If the affected limb has not yet reached 90° flexion, the check can also be performed on the patient’s healthy leg.
Check criteria at 90° flexion
The central goal of the check is for the axis of rotation of the knee joint and the axis of rotation of the device to be at the same height and parallel to each other at 90° flexion. The following table shows the possible observations and the corresponding corrective actions:
Observation at 90° flexion | Corrective action |
|---|---|
Knee joint sits higher than the two black joints of the device | Increase thigh length |
Knee joint lies lower than the two black joints of the device | Reduce thigh length |
Both joints are parallel at 90° | Setting is correct |
A correctly aligned axis is crucial not only for the effectiveness of the therapy, but also for the safety of the patient. Deviations in axis alignment can lead to shear forces on the knee joint, which is especially critical in postoperative patients. Therefore, take the necessary time for this check step and correct the thigh scale as needed until parallel alignment is achieved.
Step 4: Important notes (3:19 – 3:33)
In addition to the technical settings, there are two points that require particular attention in practical use.
Position of the rear leg shell
Make sure that the rear leg shell is not positioned too low. Under no circumstances should it fall in front of the chrome-plated strut. An incorrectly positioned rear leg shell can impair the therapy and, in the worst case, lead to incorrect loading of the leg. Check the position of the rear leg shell every time the device is readjusted.
Switch off the device after therapy
After each therapy session, the device should be switched off at the main switch. This protects the device, prevents unintended movements, and ensures a safe state between therapy sessions.
Step 5: Release the key lock (3:34 – 3:42)
The ARTROMOT K1 is equipped with a key lock that prevents unintended changes to the settings by the patient. This function is particularly relevant when the device is used for home therapy and the patient works with it independently.
Release the key lock
To release the key lock and be able to change settings again, proceed as follows:
Press the two left buttons simultaneously for a few seconds.
The lock is released and the settings can be changed again.
This function is intended exclusively for specialist staff. Patients should be informed that setting changes may only be made by qualified personnel.
Overall overview: All setup steps at a glance
Step | Content | Video timestamp |
|---|---|---|
Step 1 | Preparation and measurement: patient positioning, thigh measurement, device preparation, adjusting the foot shell | 0:00 – 1:10 |
Step 2 | Setup on the patient: insert the leg, adjust the leg shells, configure the range of motion | 1:11 – 2:38 |
Step 3 | Check the setup: axis check at 90° flexion, correction of the thigh scale | 2:39 – 3:18 |
Step 4 | Important notes: position of the rear leg shell, switching off after therapy | 3:19 – 3:33 |
Step 5 | Release the key lock: Press the two left buttons simultaneously | 3:34 – 3:42 |
ARTROMOT K1 in use: Practice context for specialist staff
The ARTROMOT K1 is used postoperatively to ensure controlled, passive motorized movement of the knee joint. Typical indications are procedures on the knee joint in which early mobilization supports the healing process, prevents the formation of adhesions, and activates the synovial fluid for cartilage nutrition. You can find more about the background and benefits of CPM therapy after knee surgery in the article CPM device after knee surgery on the WINTER Medizintechnik blog.
For optimal therapy success, it is crucial that the device is not only set up correctly but also maintained regularly. As an official ARTROMOT service partner in Switzerland, WINTER Medizintechnik offers both rental devices and support for questions about setup and maintenance.
For clinics and practices that need devices for their patients, the rental service for knee CPM devices is available. The devices are delivered personally and set up professionally so that patients can carry out the therapy safely at home. The WINTER Medizintechnik team is available for questions about setup, handover, and support.
In addition to the knee CPM device, WINTER Medizintechnik also offers CPM devices for other joints, including shoulder CPM devices and elbow CPM devices. The setup principles differ depending on the device and joint, which is why specific instruction by specialist staff is recommended for each device.
Quick overview: Setting parameters
Parameter | Description | Reference value / note |
|---|---|---|
Thigh length | Greater trochanter to center of the knee | Measure individually |
Speed | Initial speed of movement | Approx. 35% |
Extension (extension) | Upper left rotary knob | Maximum pain-free value |
Flexion (flexion) | Upper right rotary knob | Maximum pain-free value |
Foot shell | Position and pretension | Upright, slightly pretensioned |
Lower leg length | Distance from center of the knee to heel | Initially set to maximum, then adjust |
Leg shell height | Contact with thigh/lower leg | Only light contact, no pressure |
Checklist before starting therapy
Patient is lying on a surface that is not too soft
Thigh length measured and noted
Power cable connected, main switch turned on
Thigh scale set correctly
Speed set to approx. 35%
Foot shell positioned upright and slightly pretensioned
Center of the knee lies between the knee pivot points of the device
Foot section slid toward the heel and screws tightened
Leg shells have only light contact (no pressure)
Thigh and lower leg parallel to the side tubes
Extension limited (upper left knob)
Flexion limited (upper right knob)
Check performed at 90° flexion (or on the healthy leg)
Rear leg shell is not positioned in front of the chrome-plated strut
Cloth placed on the leg supports
Frequently asked questions about setting up the ARTROMOT K1
How do I know whether the device is positioned correctly on the leg?
The most reliable indicator is the check step at 90° flexion: if the joint axes of the knee and device are at the same height and parallel to each other, the device is positioned correctly. If there are deviations, the thigh scale must be adjusted accordingly.
What should I do if the patient reports pain during therapy?
All movements should be performed exclusively within the pain-free range. If a patient reports pain, the range of motion must be reduced. Maximum flexion is limited with the upper right rotary knob, and maximum extension with the upper left rotary knob. If in doubt, therapy should be interrupted and the treating doctor consulted.
How long does it take to set up the device?
The complete setup, from measuring the thigh length to the final axis check, requires care and should not be performed under time pressure. Experienced specialist staff can carry out the process efficiently without compromising precision.
Does it need to be readjusted every time it is used?
If the device is always used by the same person and no clinical changes (for example, increasing mobility) have occurred, existing settings can be retained. However, the range of motion should be adjusted regularly, as it is gradually expanded over the course of therapy. As a general rule: each new application of the device should be completed with an axis check.
What surfaces are suitable for positioning the patient?
Firm, level surfaces such as a treatment table or a firm bed are suitable. Very soft mattresses are unsuitable because the device can sink into them and the setup will be distorted.
