In the normal hand, the power generated varies according to the width of span. Power is maximal at either the second or third setting. This is influenced by the size of hand.

Usually, the trace seen after injury parallels normal. Exceptions are seen in patients with flexion deficits who cannot exert effective grip on small diameters. Nevertheless, their traces return to a parallel pattern at larger spans.

Flat or eccentric traces suggest submaximal effort. This can occur in patients who are experiencing pain such as is caused by neuromata. It is, however, characteristic of malingering. There are techniques which can overcome deception.

Maximum grip strength varies greatly and is correlated to:

• Height
• Weight
• Age
• Sex - women 60-70% of men
• Hand dominance - dominant 5-10% stronger than non-dominant.
• Occupation
• Hobbies

Expected values (Kg, mean±SD) are:

The individual contribution of the fingers and therefore the expected effect of amputation are:

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Operative series index	British Society for Surgery of the Hand