There are three major categories of ambulatory assistive devices: canes, crutches, and walkers. In this post, we will talk only about canes. Stay tuned for the next posts about crutches and walkers.
Assistive devices are prescribed for a variety of reasons, including problems of balance, pain, fatigue, weakness, joint instability, excessive skeletal loading, and cosmesis. Another primary function of assistive devices is to eliminate weight bearing fully or partially from a lower limb. This unloading occurs by transmission of force from the upper limbs to the floor by downward pressure on the assistive device.
Most canes used in current clinical practice are constructed of lightweight aluminum. The function of a cane is to widen the base of support (BOS) and improve balance. Canes are not intended for use with restricted weight bearing gaits (such as non- or partial-weightbearing). Patients are typically instructed to hold a cane in the hand opposite the affected extremity. This position of the cane most closely approximates a normal reciprocal gait pattern with the opposite arm and leg moving together.
Contralateral positioning of the cane is particularly important in reducing forces created by the abductor muscles acting at the hip. During normal gait, the hip abductors of the stance extremity contract to contract the gravitational moment at the pelvis on the contralateral side during swing. This prevents tilting of the pelvis on the contralateral side but results in a compressive force acting at the stance hip. Use of a cane in the upper extremity opposite the affected hip will reduce these forces. The floor (ground) reaction force created by the downward pressure of body weight on the cane counterbalances the gravitational movement at the affected hip. Thus, the need for tension in the abductor muscles is reduced, with a subsequent decrease in joint compressive forces.
This assistive device also is referred to as a regular or conventional cane. It is made of aluminum, wood or plastic and has a half circle (“crook”) or a straight (or offset) handle . The distal rubber tip is at least 1 in. in diameter or large. It can also be adjustable to the patient’s height using a push-button mechanism (adjustments within the range of approximately 27 to 38.5 in.).
Advantages: This cane is inexpensive and fits easily on stairs or other surfaces where space is limited.
Disadvantages: If it is not adjustable, it must be cut to fit the patient. Its point of support is anterior to the hand, not directly beneath it.
Quad (Quadruped or Four-Prong Cane)
The characteristic feature of these canes is that they provide a broad base with four points of floor contact. each point (leg) is covered with a rubber tip. The legs closest to the patient’s body are generally shorter and may be angled to allow foot clearance. On may designs the proximal portion of the cane is offset anteriorly. The handpick is usually one of a variety of contoured plastic grips. A telescoping design allows for height adjustments.
Advantages: This cane provides a broad-based support. Bases are available in several different sizes.
Disadvantages: Depending on the specific design of the cane, the pressure exerted by the patient’s hand may not be centered over the cane and may result in patient complaints of instability. As a result of the broad BOS, some quad canes may not be practical for use on stairs. They also warrant use of a slower gait pattern. If a faster forward progression is used, the cane often “rocks” from rear legs to front legs, which decreases effectiveness of the cane. Patients should be instructed to place all four legs of the cane on the floor simultaneously to obtain maximum stability.
This cane provides a wide wheeled base allowing uninterrupted forward progression. it includes contoured handholds, easy height adjustment from 28 to 37 in., and a pressure-sensitive brake built into the handle engaged using pressure from the base of the hand.
Advantages: The wheeled base allows weight to be continuously applied as the need to lift and place the cane forward is eliminated. This also provides for a faster forward progression. The second and third handles placed between the uprights can assist in rising to standing (brake engaged).
Disadvantages: it is more costly than standard quadruped canes, and requires sufficient upper extremity and grip strength to engage the braking mechanism. This cane is not suitable for patients displaying a propulsive gait pattern (e.g., Parkinson’s disease).
A general consideration relevant to all canes is the nature of the handgrip. There are a variety of styles and sizes available. the type of handgrip should be judged and selected primarily on the basis of patient comfort and on the grip’s ability to provide adequate surface area to allow effective transfer of weight from the upper extremity to the floor. The more common types of handgrips are:
- The crook handle
- The straight or offset handle
- The shovel handle, and
- The pistol handle, which conforms to the patient’s hand.
it is useful to have several handgrip styles available for examination and trial with individual patients.
In measuring cane height, the cane (or center of a broad-based cane) is placed approximately 6 in. from the lateral border of the toes. two landmarks typically are used during measurements: the great trochanter and the angle at the elbow. The top of the cane should come to approximately the level of the greater trochanter, and the elbow should be flexed to about 20 to 30 degrees. Because of individual variations in body proportion and limb lengths, the degree of flexion at the elbow is generally considered the more important indicator of correct cane height.
This elbow flexion serves two important functions. it allows the arm to shorten or to lengthen during different phases of gait, and it provides a shock-absorption mechanism. Finally, as with all assistive devices, the height of the cane should be considered with regard to patient comfort and the cane’s effectiveness in accomplishing its intended purpose.
Gait pattern for use of canes
As discussed, the cane should be held in the upper extremity opposite the affected limb. For ambulation on level surfaces, the cane and the involved extremity are advanced simultaneously. The cane should remain relatively close to the body and should not be placed ahead of the toe of the involved extremity. These are important considerations, because placing the cane too far forward or to the side will cause lateral and/or forward bending, with a resultant decrease in dynamic stability.
When bilateral involvement exists, a decision must be made as to which side of the body the cane will be held. This question is most effectively resolved by a problem-solving approach with input from both the patient and the therapist.
Assuming Standing and Seated Positions with a Cane
Coming to standing
- Patient moves froward in chair.
- Cane is positioned on uninvolved side (broad-based cane) or leaned against armrest (standard cane).
- Patient leans forward and pushes down with both hands on armrests, comes to a standing position, and then grasps cane. With use of a standard cane, the cane may be grasped loosely with fingers prior to standing and the base of the hand used for pushing down on armrests.
Return to sitting
- As the patient approaches the chair, the patient turns in a small circle toward the uninvolved side.
- The patient backs up until the chair can be felt against the patient`s legs.
- The patient then reaches for the armrest with the free hand, releases the cane (broad-based), and reaches for the opposite armrest. A standard cane is leaned against the chair as the patient grasps the armrest.
- The unaffected lower extremity leads up.
- The cane and affected lower extremity follow.
- The affected lower extremity and cane lead down.
- The unaffected lower extremity follows.
Source: Susan B. O`Sullivan, Thomas J. Schmitz. Physical Rehabilitation.