Introduction: Machinery is the single most common cause of acute occupational hand injury in our hospital.
Objective: To identify the pattern and determine the causes of acute upper limb injury resulting from the use of machines.
Material and methods: Case-crossover study design was used. Two hundred and nine (97%) of all 216 patients who had an acute upper limb injury when using a machine and who presented to Tikur Anbessa hospital between November 2004 and October 2005 were examined
Result: The majority of our patients were young (mean age 28.5 years), male (95%) and working in manufacturing industry 181 (87%). Ninety (43%) were machine operator, and had worked less than one year 122 (58%) with short term contract 120 (57%). The majority were not trained formally either for the task they were doing 168 (80%), or for safety measures 178 (85%). A safety guard was present only in a few machines 31 (15%) and half of these were being used. Most of the injuries occurred shortly after lunch. Very many of the injuries were severe with a resulting amputation 47% and fracture 35%. The mean permanent disability was 20%. Doing unfamiliar tasks was associated with the highest relative risk (increase by 14 fold) followed by being rushed (RR = 12), being distracted (RR = 8), using alfunctioning equipment (RR = 8) and using unaccustomed technique to do a task (RR = 6). Wearing gloves decreased the risk by 83%. Job category, work experience, training on the task and safety training significantly modified the transient risk factors.
Conclusion: the incidence of occupational upper limb machinery injuries could be reduced by avoiding transient risk factors and by providing safety training.