Hand injury: association of handedness with cause and site of injury

Author Information

W. Kaisha, MBChB (UoN), MMed (Surg), Assistant Lecturer, Department of Human Anatomy, University of
Nairobi, and Senior Registrar of Surgery, Kenyatta National Hospital, P.O. Box 368-00202, Nairobi, Kenya,
S. Khainga, MBChB (UoN), MMed (Surg), Lecturer, Department of Surgery, University of Nairobi, and
Consultant Surgeon, Kenyatta National Hospital, P.O. Box 30197, Nairobi, Kenya

Corresponding Author: Dr. W. Kaisha, Department of Surgery, Kenyatta National Hospital, P.O. Box 368-
00202, Nairobi, Kenya, Email:

Abstract

BACKGROUND: Most people have a dominant hand: right or left. The dominant hand for most purposes is that which is used for writing. The performance, reflex activity and exposure of these hands differ. Due to this asymmetry, it is possible that handedness may influence the likely causes, the lateralization and pattern of injury.

OBJECTIVE: This study was designed to assess the association of hand dominance to the causes, lateralization and pattern of hand injuries.

SETTING: Kenyatta National Hospital, a national referral and teaching hospital in Nairobi, Kenya.

METHODOLOGY: A prospective analysis of consecutive patients who presented with unilateral hand injuries between May and August 2006 at (KNH) was done. Data on hand dominance, hand injured, causes and pattern of injury were collected using a questionnaire. Associations were investigated using student’s t-test and Chi square tests, with level of significance taken as < 0.05. Yates correction and Fischer’s exact tests were used where the cell value was less than 5.

RESULTS: A total of 99 patients with hand injuries were recruited. Ninety four were right handed, three left handed, with two ambidextrous. The dominant hand was injured in 47 (48.5%), while the non-dominant hand was injured in 51.5% of the cases (p = 0.27). The most common causes of injury were occupational (31.3%) and assaults (30.3%). Falls on the hand caused injury more on the dominant hand (p=0.03) than the non-dominant one. Hand dominance had no influence on the other causes, nor did it have influence on the lateralization and pattern of injury.

CONCLUSION: With the exception of falls, hand dominance has no influence on causes, lateralization and pattern of hand injury.

Introduction

Hand injuries are common and may account for 5-10% of emergency department admissions (1). The injury may be unilateral or bilateral. Several studies have assessed the correlation between hand dominance and lateralization of injury(26) with some suggesting that hand dominance influences lateralization of injury (2-5), while others disagree (3,6). However, the effect of handedness on site and pattern of injury has not been described.

An individual’s handedness can be determined by observing hand use during various tasks (7). The hand preferred for use during most tasks is considered to be the dominant one. Various tests, with a score obtained can be employed to determine handedness, but writing is the activity that best predicts handedness (7).

Materials and methods

The study was conducted among consecutive patients with acute unilateral hand injuries who presented at KNH Accident and Emergency (A&E) department between May 2006 and August 2006. To be eligible for the study, subjects must have had an injury involving any part of the hand, hand being considered to be any part distal to the distal wrist crease. Patients excluded were those with: burn injuries, previous hand injuries and bilateral injuries. The study was approved by the KNH Ethics and Research Committee. Informed consent was sought from the participants of this study. A questionnaire was used to extract data at the A & E department. Statistical Package for Social Sciences (SPSS) 11.5 (Chicago-Illinois) software was used for data entry and analysis. Associations were investigated using the student’s t–test, the Chi-square test with level of significance taken as < 0.05. Yates correction and Fisher’s exact tests were used where the expected cell value was less than 5.

Results

A total of 99 patients were recruited into the study. Ninety four (95 %) were right handed while 3(3%) were left handed with the ambidextrous group forming 2% (n =2).The dominant hand and non-dominant hands were injured in almost equal proportions. Comparing the individual’s handedness and the hand injured, those who were right handed had the dominant hand injured in 44 cases (46.8%) while the non-dominant hand was injured in 50 cases (53.2%). Those who were left handed had only their dominant hand injured. There was no difference between the likelihood of the dominant hand and the non-dominant hand being injured (P= 0.27).

The most common cause of injury was work (while operating any form of equipment) or machine related (occupational). This represented 31.3% (n=31) of the patients, followed by assaults, which affected 30 patients (30.3%). Falls caused injury in 10 patients (10.1%) and hand being caught in objects affecting 8 patients (8.1%) which was similar in prevalence to road traffic accidents (Table 1). The distribution of the causes of injury was similar for the dominant and non-dominant hand except for falls. The dominant hand was twice as likely to be injured in a fall compared to the non-dominant hand (p-value 0.003, RR 1.78).

Table 1: Influence of hand dominance on cause of injury

Injured handDominant, n    Non-dominant, nRR*p-value*

Injury at work/machinery14170.900.65

Assault15151.050.83

Fall on hand821.780.03

Road traffic accident441.030.60

Hand caught between objects350.760.39

Sports related111.030.73

Cutting/piercing03–0.14

Knife injury111.030.73

Broken glass10 2.090.48

Other13

The most predominant site of injury was the carpus, 28% (hand minus the digits). Among the fingers, the ring was the most commonly injured (23%) with the little finger being least injured (11.6%). Most patients had open injuries, with integument being the most affected structure, followed by fractured bones. Of the bones, the phalanges were the most affected. The distribution of injuries according to the site and pattern of injuries versus the hand injured are shown in Table 2. The regional distribution of injuries was similar for dominant and nondominant hands.

Table 2: Site and pattern of injury

Injured handDominant, n    Non-dominant, nRR*p-value*

Site

 

Thumb

881.00 0.99

               Index11111.02 0.93

               Long11120.96 0.88

               Ring11150.81 0.42

               Little  761.08 0.81

               Carpus15170.95 0.82

Pattern

 

Integument

34430.710.17

              Phalangeal fracture29261.10 0.50

               Metacarpal fracture7120.67 0.20

               Joints541.08 0.56

              Tendons10110.95 0.85

Discussion

The present results have shown that the dominant and non-dominant hands were injured in almost equal proportions and that handedness was not predictive of the increased likelihood of one hand being injured. This compares well with the study by Shaheen et al in Qatar and Mink in the USA (4) but at variance with that of Porac (3) in a