Chapter 5

Hand function of people with tetraplegia

Loss of hand function is often more important to people with tetraplegia than loss of lower limb function and the inability to walk.¹^,² This reflects the importance of hand function for independence. The purpose of this chapter is to describe how people with different patterns of paralysis use their hands and to outline some of the splints and adaptive equipment commonly prescribed. The use of surgery and electrical stimulation to improve hand function will also be discussed.

The same generic framework advocated for devising physiotherapy programmes in Chapter 2 can be used for hand management. Initially, goals of treatment are negotiated with the patient. Goals need to also be set in conjunction with occupational therapists and other team members who share responsibility for their attainment. Goals are expressed with respect to activity limitations such as taking a spoon to the mouth and using a keyboard. Goals can also be expressed with respect to participation restrictions such as dining out with friends or returning to work. Once realistic goals are defined, impairments preventing the attainment of each goal are identified but only with respect to impairments which physiotherapy can address. These typically include poor strength, joint mobility and skill.

The hand function of patients with tetraplegia is primarily limited by neurological status (see Appendix). Below is a summary of the hand function typically attained by a patient with different ASIA motor complete lesions.

Hand function and principles of therapy

C4 and above tetraplegia

Patients with C4 and higher levels of tetraplegia have no upper limb function.

Therapy for these patients is directed at preventing contractures. It is important to prevent contractures because they can be unsightly and create problems with hygiene and personal care. Contractures of the hand are probably best avoided with prolonged stretch and regular passive movements (see Chapter 9). Prolonged stretch can be administered with splints. In patients without contractures, the appropriate type of splint is determined by the type of contractures patients are most likely to develop. For example, patients with total paralysis of the hands commonly develop metacarpophalangeal (MCP) joint hyper-extension and interphalangeal (IP) joint flexion contractures. Therefore the appropriate splint is one which immobilizes these joints in a stretched position, namely MCP joint flexion and IP joint extension (see Figure 5.1). A less aggressive ‘functional’ splint which places the hand in a neutral position does not stretch these joints and is probably less effective for preventing these types of contractures. In patients with existing contractures, the appropriate type of splint is determined on a case-by-case basis but the splint needs to provide a substantial stretch to affected joints.

Figure 5.1 A splint which flexes the MCP and extends the IP joints of the fingers can be used to prevent MCP hyper-extension contractures and IP flexion contractures. Alternatively, it can be used to promote a tenodesis grip in patients with C6 tetraplegia. The thumb can be held against the index finger with tape or a thumb piece incorporated into the splint.

Tenodesis grip

A tenodesis grip is a method of grasping used by patients with C6 and C7 tetraplegia who have paralysis of finger and thumb flexor muscles but active wrist extension. The tenodesis grip relies on passive tension generated in the paralysed extrinsic finger and thumb flexor muscles (flexor digitorum superficialis, flexor digitorum profundus and flexor pollicis longus) with wrist extension.3–8 The open hand is placed around an object with the wrist flexed. The wrist is then actively extended, increasing the passive tension in the paralysed finger and thumb flexor muscles and pulling the fingers and thumb into flexion. In this way, objects can be grasped between the paralysed thumb and index finger or in the palm of the hand (see Figures 5.8 and 5.9). A tenodesis grip provides crude but nonetheless useful hand function.⁷ Some patients can enhance the effectiveness of their tenodesis grip by eliciting spasm in the extrinsic thumb and finger flexor muscles with wrist extension.

The tenodesis grip can be used to grasp objects between the thumb and index finger using either a lateral key or pincer grip. In the lateral key grip the pad of the thumb contacts the side of the index finger (see Figure 5.8b) and in the pincer grip the tip of the thumb contacts the tip of the index finger (see Figure 5.9b). The type of grip attained is primarily determined by the extensibility of the thumb adductor muscles. A pincer grip is attained if the thumb adductors are extensible and a lateral key grip is attained if the thumb adductors are inextensible. The point of contact between the thumb and index finger also depends to a lesser degree on the relative lengths of the thumb and index finger, and the extensibility of the extrinsic finger flexor muscles.³^,⁴

A lateral key grip is generally considered easier to achieve because it requires less precision to ensure the thumb hits the side of the index finger. Provided the thumb hits anywhere along the medial aspect of the finger, some type of grip will be attained. In contrast, a pincer grip is reliant on the thumb meeting the index finger at precisely the tip of the finger. If there is slight overstretching of the thumb adductor muscles, the thumb will miss its target. When a pincer grip can be attained it provides better fine control than a lateral key grip; however, it is less powerful than a lateral key grip. Sometimes it is advantageous to promote a pincer grip in one hand and a lateral key grip in the other.

While the tenodesis grip is primarily used by patients with C6 and C7 tetraplegia, some patients with C5 tetraplegia can also use a crude type of tenodesis grip. Patients with C5 tetraplegia have paralysis of the wrist extensor muscles so they cannot actively extend the wrist to close the hand. They may, however, be able to use forearm supination to manipulate the position of the wrist. With the forearm in pronation, gravity pulls the wrist into flexion. With supination, gravity pulls the wrist into extension. Thus manipulation of the forearm can be used to change wrist position which in turn opens and closes the hand. This type of grip is sometimes called a passive tenodesis grip because wrist position is passively manipulated by forearm rotation. However, the terminology is not ideal because it implies that the tenodesis grip of patients with C6 and C7 tetraplegia is active and hence due to something more than the passive mechanical properties of the hand.

The passive tenodesis grip of people with C5 tetraplegia is of limited functional use and most patients gain superior upper limb function from splints which stabilize the wrist (see Figure 5.5). A passive tenodesis grip cannot be used in conjunction with these splints because the splints prevent passive wrist extension. However, strategies appropriate for promoting a tenodesis grip in patients with C6 and C7 tetraplegia are also appropriate for promoting a passive tenodesis grip in people with C5 tetraplegia.

Splinting and taping to promote a tenodesis grip

The effectiveness of a tenodesis grip is often compromised because of excessive extensibility in the extrinsic thumb and finger flexor muscles. When these muscles are too extensible, wrist extension produces only weak thumb and finger flexion. The best way to increase the ‘strength’ of the tenodesis grip is to induce shortening (i.e. decrease extensibility) of the extrinsic thumb and finger flexors.

Splinting and taping are widely used to encourage loss of extensibility in the extrinsic finger and thumb flexor muscles and promote a tenodesis grip. However, it remains unclear whether either intervention can decrease the passive extensibility of the extrinsic finger and thumb flexor muscles and improve hand function.⁸^,⁹ This controversy is discussed in more detail below.

Splinting and taping programmes to promote a tenodesis grip may need to be withheld if patients are likely to have hand surgery. Often the effectiveness of hand surgery relies on good extensibility in the finger and thumb flexor muscles. However, the difficulty with this approach is that often the decision about hand surgery is not made until 1 or 2 years after injury. Consequently, it is not always clear which patients will and will not ultimately be suitable candidates. In addition, some patients suitable for hand surgery do not elect to have it (see p. 104 for further discussion).² The dilemma for therapists is whether they should compromise hand function by withholding strategies designed to promote a tenodesis grip on the basis that patients may have hand surgery in the future.

A theoretical basis for splints designed to promote a tenodesis grip

Animal studies have convincingly shown that immobilization of muscles at short lengths induces shortening (see Chapter 9). On this basis, it has been argued that the best way to promote a tenodesis grip is with a splinting or taping regime which immobilizes the extrinsic finger and thumb flexor muscles in their shortened positions. To achieve this, one of two splinting regimens is probably best adopted. The more conservative approach is to splint the hand in a relatively neutral position with the MCP joints fully flexed, the IP and wrist joints extended and the thumb flexed against the side of the index finger (see Figure 5.1). This type of splint immobilizes the extrinsic finger and thumb flexor muscles in a relatively shortened position but discourages extension contractures of the MCP joints and flexion contractures of the IP joints.

A second more aggressive approach is to flex the MCP and proximal IP joints of the fingers with the thumb positioned against the side of the index finger. This is typically done by applying tape across the back of the fingers and thumb (see Figure 5.10). The wrist is held in an extended position with a splint. The flexed position of the fingers places the extrinsic finger flexor muscles in a shortened position. However, it also substantially increases the risk of undesirable flexion contractures of the proximal IP joints. If this second approach is used, the hand needs to be carefully monitored and patients should spend at least some time of each day with the proximal IP joints in full extension. In addition, passive movements to the proximal IP joints should be regularly administered. Whenever the IP joints are extended, the wrist and MCP joints need to be flexed to avoid stretch of the extrinsic finger flexor muscles (see Figure 5.11).