Merck Manual

Please confirm that you are a health care professional

honeypot link

Therapeutic and Assistive Devices


Alex Moroz

, MD, New York University School of Medicine

Last full review/revision Jun 2017| Content last modified Jul 2017
Click here for Patient Education
Topic Resources

Orthoses provide support for damaged joints, ligaments, tendons, muscles, and bones. Most are customized to a patient’s needs and anatomy. Orthoses designed to fit into shoes may shift the patient’s weight to different parts of the foot to compensate for lost function, prevent deformity or injury, help bear weight, or relieve pain, as well as provide support. Orthoses are often very expensive and not covered by insurance.

Walking aids include walkers, crutches, and canes (see Figure: Correct cane height). They help with weight bearing, balance, or both. Each device has advantages and disadvantages, and each is available in many models. After evaluation, a therapist should choose the one that provides the best combination of stability and freedom for the patient (see Table: Ambulation Aids). Physicians should know how to fit crutches (see Figure: Fitting crutches). Prescriptions for assistive devices should be as specific as possible.

Correct cane height

The patient’s elbow should be bent at slightly < 45° when maximum force is applied.

Correct cane height

Fitting crutches

Patients should wear the type of shoes usually worn, stand erect, and look straight ahead with the shoulders relaxed. For a correct fit, the end of each crutch should be placed about 5 cm from the side of the shoe and about 15 cm in front of the toe, and the top of the crutch should be about 2 to 3 finger widths (about 5 cm) below the axilla. The hand grip should be adjusted so that the elbow bends 20 to 30°.

Fitting crutches

Wheelchairs provide mobility to patients who cannot walk. Some models are designed to be self-propelled and to provide stability for traveling over uneven ground and up and down curbs. Other models are designed to be pushed by an assistant; they provide less stability and speed. Wheelchairs are available with various features. For athletic patients with impaired lower extremities but good upper body strength, racing wheelchairs are available. A one-arm–drive or hemi-height wheelchair may be suitable for hemiplegic patients with good coordination. If patients have little or no arm function, a motorized wheelchair is prescribed. Wheelchairs for quadriplegics may have chin or mouth (sip and puff) controls and built-in ventilators.

Mobility scooters are battery-powered, wheeled carts with a steering wheel or tiller, speed control, and ability to move forward and in reverse. They are used on firm, level surfaces inside and outside buildings but cannot negotiate curbs or stairs. Scooters are helpful for people who can stand and walk short distances (ie, to transfer to and from the scooter) but who lack the strength and/or stamina to walk longer distances.

Prostheses are artificial body parts, most commonly limbs designed to replace lower or upper extremities after amputation (see Leg Amputation Rehabilitation). Technical innovations have greatly improved the comfort and functionality of prostheses. Many prostheses can be cosmetically altered to appear natural. A prosthetist should be involved early to help patients understand the many options in prosthetic design, which should meet the patients’ needs and safety requirements. Many patients can expect to regain considerable function. Physical therapy should be started even before the prosthesis is fitted; therapy should continue until patients can function with the new limb. Some patients seem unable to tolerate a prosthesis or complete the physical rehabilitation required to successfully use it.


Ambulation Aids






Very good


Least stable

Walking speed



Can be fast

Use on steps


Training needed


Strength of arms required for use


Moderate strength


Number of hands required for use


Usually 2

Usually 1

Possibility of carrying objects

Requires attachment of basket




Most expensive

Relatively inexpensive

Least expensive

Click here for Patient Education
NOTE: This is the Professional Version. CONSUMERS: Click here for the Consumer Version
Professionals also read

Test your knowledge

Overview of Exercise
Prior to beginning an aerobic exercise, which of the following activities seems to be most effective for facilitating safe exercise? 
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID

Also of Interest