Knee immobilizers are removable devices that maintain stability of the knee.
Knee immobilizers are typically used for injuries that benefit from immobilization but can tolerate brief periods without immobilization and thus do not require casting.
- Certain tibial plateau fractures
- Knee fractures and ligament injuries that require immobilization while awaiting nonemergent operative repair or casting
- Certain ligament injuries that do not require repair (as definitive treatment)
- Patellar tendon injury
- Patellar dislocation
- Quadriceps tendon injury
- Open fractures
- Lower extremity deep vein thrombosis
- Joint stiffness
- Commercially available knee immobilizer*
* There are different brands, but they all typically consist of a heavy foam/cloth wrap that extends from mid-calf to mid-thigh. The wrap is held in place by a series of straps and provides support by its bulk. Additional stability is achieved by removable rigid strips that are applied to the medial and lateral sides of the device and held in place by hook-and-loop connections.
- Any open wounds should be treated and covered appropriately prior to application of the knee immobilizer.
- Rarely, analgesia is required.
- Knee ligament injuries may involve the medial collateral, anterior cruciate, lateral collateral, and/or posterior cruciate.
- Lie the patient supine with the foot supported and the knee extended.
Step-by-Step Description of Procedure
Follow any available product-specific instructions and recommendations.
- Prepare the knee immobilizer and straps.
- Place the immobilizer behind the leg and centered behind the knee vertically and laterally.
- If the immobilizer has a patellar cutout, align the cutout over the patella.
- If the immobilizer has removable or adjustable stabilizer bars, place the bars medially and laterally along the long axis of the leg.
- Secure the stabilizer bars and the immobilizer with the fastener straps (eg, hook and loop) above and below the knee (typically 2 above and 2 below the knee).
- Check distal sensation and capillary refill.
- Prescribe crutches as needed and instruct patients on their use.
- Arrange or recommend appropriate follow-up.
- Advise patients to be alert for symptoms of deep vein thrombosis and return immediately for evaluation should they occur.
- Advise patients to return for pain that cannot be controlled with oral drugs (indicating a need for evaluation for compartment syndrome).
Warnings and Common Errors
- Do not apply the immobilizer too low on the leg because that does not effectively immobilize the knee.
- If the stabilizer bars are already attached to the immobilizer in the package, they are unlikely to be in the correct place and must be repositioned.
- If the legs taper significantly (ie, very large thighs compared to the rest of the leg), the immobilizer may tend to slip down; this may not be apparent until the patient stands.
Tips and Tricks
- Tighten the straps from bottom to top.
- Prescribe crutches unless you confirm that the patient can walk without them.