HANDEDNESS AND HAND INJURIES

A. A. BEATON, L. WILLIAMS and L. G. MOSELEY

From the Brain, Behaviour and Cognition Group, Department of Psychology, and the Department of Mathematics and Computer Science, University College of Swansea, Swansea, Wales, UK

Data are reported from a study of 1,003 patients attending with hand injuries at an Accident and Emergency Department. Among both left- and right-handers, injuries to the right hand were more common than to the left hand, except for accidents to right-handers at work. For this group there were more injuries to the left hand. Male and female patients differ in the frequency with which they present for medical attention but show similar types of injury. Journal of Hand Surgery (British and European Volume) 19B: 158-161

In a study of 297 industrial accidents involving the hands, Wilkes (1956) found that 154 occurred to the right hand and 143 to the left hand. 30 years later, Absoud and Harrop ( 1984) analyzed 150 cases of injury at work. They wrote “like Wilkes (1956), we found the non-dominant hand to be injured slightly more frequently than its fellow”, but Absoud and Harrop do not provide a breakdown of the number or percentage of injuries to the left and right hands. The same applies to a study by Campbell (1985) of 383 patients who had suffered moderate or severe hand injury. Clark et al (1985) found that “of 721 patients asked, 433 (60%) had injured their dominant hand”. More recently, Hollis and Watson ( 1993) analyzed a series of 111 consecutive hand injuries and reported that “left and right hands are injured with equal frequency”. Thus there has not been any substantial difference in incidence of injury to left and right hands when the number of cases is relatively small, but when the number of cases is larger there appear to be more injuries to the right hand.

None of the above authors considered left-handers in any detail (if they were mentioned at all), probably because small numbers of left-handers were included in the studies. It is of interest to know whether left-handers have the same pattern of hand injuries as right-handers or whether they show the opposite pattern. There are grounds for supposing that there might be a difference in the relative risk of injury to the two hands between right and left-handed groups. For some tasks left- handers perform better with their non-preferred (right) hand than do right-handers with their non-preferred (left) hand, even though there is no difference in skill between the preferred hands of left- and right-handers (Peters, 1980; Kilshaw and Annett, 1983; Beaton and Maguire, 1993; Provins and Magliaro, 1993). This might lead to a decrease in the risk of right hand injury among left-handers.

The purpose of the present study was to investigate the relative frequency of injury to left and right hands in a sufficiently large sample of cases to include a reasonable number of left-handers. A second objective was to examine the pattern of hand injury according to sex and as a function of the place where the injury occurred.

METHOD

A prospective study of patients seeking medical attention for an injury to the hand was undertaken. All respon- dents had presented themselves to the Accident and Emergency (A and E) Department of a District General Hospital. The sample consisted of virtually all individ- uals who presented at a hand clinic during the period June 1 st to August 3 1 st, 1990. After appropriate medical treatment had been given, and where the operational requirements of a busy A and E Department allowed, the patient’s handedness was assessed using the Annett (1970) handedness inventory. This inventory has been shown to have good reliability (Raczowski et al, 1974) and validity (Annett, 1970; 1976).

Data were collected as to the time, date, place and circumstances in which the injury occurred, and the age, sex and employment status of the patient were noted.

RESULTS

The sample consisted of 756 male and 238 female patients, and nine others whose sex was not recorded.

Since various details were not always recorded (the hand preference questionnaire was not completed for approximately one-tenth of the sample), the total num- bers in the different Tables in this paper do not always correspond.

Table 1 shows a breakdown of the frequency of acci- dents in terms of gender and age. The youngest attender was aged 12 years (the arbitrarily decided lower age limit we placed on participants in the study), and the oldest was 87 years; more than half (55.8%) of attenders were aged 30 years or under.

The difference in the distribution for male and female patients was significant (x” = 24.47, df = 7, P < 0.0009)

Table l-Accident frequency for male and female patients of different ages

Sex Age (years)

<16 16-20 21-25 26-30 31-40 41-50 51-60 >60

Male 39 135 137 112 136 84 62 45 Female 19 34 36 18 38 34 29 21

15X

HANDEDNESS 159

due to the disproportionate number of men in the age range 16-40 years. An over-representation of young men is found in trauma data generally (Royal College of Surgeons Report of the Working Party on the Management of Patients with Major Injuries, 1988).

Table 2 shows a breakdown by gender of the place where the accident occurred. The distribution of accident locations is significantly different for the sexes (x2= 46.81, df=l, jD<O.OOOO1).

A further breakdown of the data in terms of occu- pational status showed that among men in employment, just over half (52.8%) of the accidents occurred at work and just over one-quarter (27.9%) occurred at home. The figures for employed women revealed a more even split between accidents at home (39.8%) and at work (37.0%) than for men. The proportion of accidents which occurred at home among unemployed men was 56.4%, and among unemployed women was 78.3%.

Among our sample, a number of injuries (67 male, 18 female) were not accidental. Such non-accidental injuries mostly arose from fights or from deliberately punching a wall or window pane. These involved young people of both sexes, but apart from age there was nothing to dislinguish them from the sample as a whole. Nonetheless, for certain of the comparisons given below it was considered appropriate to exclude them.

Since one of the main questions of interest in this study concerns the pattern of hand injury in left- and right-handers it was necessary to decide how our sample should be classified for handedness. This is more difficult than might be thought (Bryden, 1977; Beaton, 1985; Annett, 1985; Salmaso and Longoni, 1985; Bishop, 1990; Peters, 1992). Simply asking patients whether they are left- or right-handed (Campbell, 1985) or which is their dominant hand (Hollis and Watson, 1993) may lead to a number of individuals being mis-classified as left- handers. This is because self-reported left-handers not infrequently turn out when tested to prefer the right hand for most activities; right-handers can be more reliably designated according to self-report (Beaton, 1985).

There are a number of handedness inventories in common use which purport to measure both direction and degree of handedness. For present purposes, how- ever, we chose to classify handedness in terms of the writing hand. There are good theoretical grounds for choosing the writing hand despite the apparent problem

Table 2-Place where accident occurred

Sex Home Work sports RTA Hobby Other

Male 244 287 45 1 15 134 % 35.6 41.8 6.6 0 2.2 19.5 Female 123 42 9 1 2 54 % 53.3 18.2 3.9 0 0 23.4

Note: RTA = Road traffic accident; sports = venue; hobby = place where hobby carried out.

that there may be some natural left-handers who have been forced to write with the right hand (White and Ashton, 1976; Bryden, 1977; Annett, 1985; McManus, 1985). Moreover, we checked our results using other unimanual actions, such as throwing a ball or using a hammer, which one would not expect to be subject to educational or social pressure and obtained virtually identical results. For more sophisticated analyses of hand preference using all the data from the questionnaire see Beaton et al (1993).

When all categories of injury are included, and com- bining accidental and non-accidental injuries, the hand which was injured was the right hand in 541 cases (53.9%), the left hand in 440 (43.87%) and both hands in 12 (1.2%). In ten cases (0.9’/,) the side was not recorded. A breakdown of these figures (excluding 25 animal and human bites) in terms of writing hand is shown in Table 3 from which it can be seen that both left- and right-handed writers tend to present with accidental injury to their right hand slightly more often than their left hand.

With regard to the non-accidental injuries, right- handers present with injury to their right hand more often than to their left hand while for left-handers the reverse is the case (x2=8.30, df= 1, P<O.O04). This “dominant hand” effect is not surprising given the manner in which the majority of these injuries were sustained (i.e. punching).

Taking accidental cases and considering only left and right-handed writers and excluding injuries to both hands, there is no association (x2 < 1, df = 1, P > 0.20) between handedness and the hand injured for all patients (as in Table 3) or for either sex alone.

The association between writing hand, hand injured and place of accident (home vs work vs other) for genuine accident cases is shown in Table 4.

For right-handed writers chi-square is significant (x2 = 6.61, df=2, P< 0.04) due to the tendency for right- handers to injure their left hand at work and their right hand at home and elsewhere. For left-handed writers chi-square is not significant (x2= 1.24, df=2, P> 0.50).

Combining the data of Table 4 for left and right- handers and re-analyzing them in terms of gender showed that there was no significant association between place of injury and writing hand for either sex (x2 < 1 in each case). Nor was the association between place of

Table 3-Hand injured classified by hand used for writing

Hand injured Hand injured (accidental) (non-accidents)

Right Left Both Right Left Both

Writing hand Right 348 312 5 43 13 2 Left 50 39 ~ 3 8 1 Either 1 5 1

160 THE JOURNAL OF HAND SURGERY VOL. 19B No. 2 APRIL 1994

Table 4-Hand injured at home and at work by left- and right-handed writers (genuine accidents)

Writing hand Right Left

Hand injured. Right Left Right Left

Place of accident Home Work Other

142 115 20 16 114 131 20 13 87 61 7 9

accident and hand injured significant for either male (x2=2.42, df=2, P>O.20) or female (x2<1, df=2, P > 0.60) patients. Further statistical analysis of the data in terms of gender was not justified on account of the relatively low numbers of left-handers of each sex.

We also analyzed our data in terms of the kind of injury sustained. Laceration was the most common category of injury (40.7%) followed by fracture (15.9%). Just over 20% of the fractures were due to non-accidental causes (fights and punching walls) and most involved the fifth metacarpal. The ratio of right to left hand fractures due to such causes was approximately 3:l compared with a ratio of 3:2 for genuine accidents. Women showed the same overall pattern of injuries as men (including fractures incurred non-accidentally).

DISCUSSION

Our data show that the relative prevalence of injury to the left and right hands depends upon a number of factors, including the patient’s handedness and where and how the injury was sustained. Non-accidental injur- ies are associated with damage to the dominant or preferred hand among both right- and left-handers. Accidental injuries are generally more common to the right hand among both right- and left-handers. However, among right-handers, but not left-handers, who had sustained injuries at work we found a greater incidence of injury to the left than to the right hand. We also found that men and women present with different frequency and tend to have accidents in differ- ent locations, but there is no significant association overall between gender and either the relative frequency of injury to the two hands or in the type of injury sustained.

Our results extend the data in the literature and help to reconcile some conflicting findings. Whereas some authors have found little or no difference in frequency of accidents to left and right hands (Wilkes, 1956; Absoud and Harrop, 1984; Hollis and Watson, 1993) others have found a more substantial difference, showing a greater frequency of injury to the “dominant” (pre- sumably right) hand (Clark et al, 1985; Porac, 1993). Unlike ourselves, none of these authors presented data for a relatively large number of left-handed patients. We

have shown that what is true for right-handers only partly holds true for left-handers. Both groups show similar patterns of injury for domestic accidents in that they seek attention most often for injury to the right hand. They show mirror-image patterns of injury where accidents at work are concerned in as much as it is the non-preferred hand that is most frequently injured in each group.

Since left-handers as well as right-handers injure their right hand more than their left hand in the home, it is arguable that something in the design or use of domestic implements creates a bias towards right hand injury. Many tools and items of household equipment (e.g. scissors) are designed primarily for use by right-handers. At work, however, some additional factor over-rides this, such that right-handers, but not left-handers, injure their left hand more frequently than their right hand. Perhaps this has something to do with the way in which machinery and equipment are often fixed so as to favour operation by right-handers. Operators may have to use the right hand to operate the machine and consequently use their left hand to clear obstructions from parts which may be moving. The left hand of right-handed individuals will be less skilled than the left hand of left- handed individuals. The greater left hand skill among the latter may confer some degree of protection against injury by moving parts or in certain other risky situ- ations. In the absence of relevant evidence this, of course, remains pure speculation. Hollis and Watson (1993) claimed that “both dominant and non-dominant hands are at equal risk whatever the mechanism (of injury)” but their data were based on a comparatively small number of injuries (approximately 50 to each hand). They also failed to distinguish between the location or circumstances of injury which, as we have shown, are related to the relative frequency of injury to left and right hands.

One specific difference we found in the relative fre- quency of injury to the left and right hands concerned fractures, and especially fractures incurred during fight- ing and punching walls. In a recent study (that was also carried out in the North East of England) Packer and Shaheen (1993) reported that 21.5% of fractures and dislocations of the hand were incurred as a result of fighting. This is very similar to our own figure for fractures of 20.25%. A detailed analysis of the time of injury in our own study showed that the majority of non-accidental injuries occurred late at night and in the early hours of the morning, which arguably points to alcohol as a precipitating factor in many cases.

Acknowledgements We gratefully acknowledge the assistance of MS Julie Carr, RGN and MS Pam Ravner. RGN in the collection of data. We also thank Mr R. K. Banneriee. F<CS: and Mr C. L. Muwanga, FRCS, Consultants in Accident and Emerge&y; Sunderland District Hospital, for access to their patients.

References ABSOUD, E. M. and HARROP, S. N. (1984). Hand injuries at work. Journal

of Hand Surgery, 9B: 2: 211-215.

HANDEDNESS 161

ANNETT, M. (1970). A classification of hand preference by association analysis. British Journal of Psychology, 61: 3: 303-321.

ANNETT, M. (1976). A coordination of hand preference and skill replicated. British Journal of Psychology, 67: 4: 587-592.

ANNETT, M. Left, Right, Hand and Brain: The Right Shif Theory. Hove, Lawrence Erlbaum Associates, 1985.

BEATON, A. Left Side, Right Side. London, Batsford, 1985. BEATON, A. A. and MAGUIRE, E. (1993). Manuscript in preparation. BEATON, A. A., MOSELEY, L. G. and WILLIAMS, L. (1993). Handedness

and hand injury. In preparation. BISHOP, D. V. M. Handedness and Developmental Disorder. Oxford,

Blackwell, 1990. BRYDEN, M. P. (1977). Measuring handedness with questionnaires.

Neuropsychologia, 15: 617-624. CAMPBELL, A. S. (1985). Hand injuries at leisure. Journal of Hand Surgery,

10B: 3: 300-302. CLARK, D. P.; SCOTT, R. N. and ANDERSON, I. W. R. (1985). Hand

problems in an Accident and Emergency Department. Journal of Hand Surgery, 10B: 3: 297-299.

HOLLIS, L. J. and WATSON, D. P. (1993). The relationship between hand- edness, mechanism of injury and which hand injured. The Journal of Hand Surgery, 1XB: 3: 394.

KILSHAW, D. and ANNETT, M. (1983). Right- and left-hand skill I: Effects of age, sex and hand preference showing superior skill in left-handers. British Journal of Psychology, 74: 253-268.

McMANLJS, I. C. I[ 1985). Handedness, Language Dominance and Aphasia: A Genetic Model. Psychological Medicine, Monograph Supplement 8, 1985.

PACKER, G. J. and SHAHEEN, M. A. (1993). Patterns of hand fractures and

dislocations in a District General Hospital. Journal of Hand Surgery, 18B: 511-514.

PETERS, M. (1980). Why the preferred hand taps more quickly than the non- preferred hand: Three experiments on handedness. Canadian Journal of %sychology, 34: 62-71. _

PETERS, M. (1992). How sensitive are handedness prevalence figures to differ- ences in questionnaire classification procedures? Brain and Cognition, 18: 208-215.

PORAC, C. (1993). Hand preference and the incidence of accidental unilateral hand injury. Neuropsychologia, 31: 4: 355-362.

PROVINS, K. A. and MAGLIARO, J. (1993). The measurement of handedness by preference and performance tests. Brain and Cognition, 22: 171-181.

RACZOWSKI, D., KALAT, .I. W. and NEBES, R. (1974). Reliability and validity of some handedness questionnaire items. Neuropsychologia, 12: 43-47.

Royal College of Surgeons Report of the Working party on the Management of Patients with Major Injuries, November, 1988.

SALMASO, D. and LONGONI, A. M. (1985). Problems in the assessment of hand preference. Cortex, 21: 533-549.

WHITE, K. and ASHTON, R. (1976). Handedness assessment inventory. Neuropsychologia, 14: 261-264.

WILKES, R. (1956). A social and occupational study of injured hands. British Journal of Industrial Medicine, 13: 119-130.

Accepted: 28 September 1993 Dr Alan A. Beaton, Department of Psychology, University College of Swansea, Swansea, SA2 8PP, Wales, UK.

0 1994 The British Society for Surgery of the Hand