We made 6 types of comparisons of our results:

- by crossing the dominant and affected sides (Table 1);

- between the side affected and the type of trauma (open, closed or associated) (Table 2);

- by cross-referencing the type of lesion and the side affected (Table 3);

- by cross-referencing the type of lesion and the circumstances in which it occurred (Table 4);

- by cross-referencing lesion type and sector of activity (Table 5);

- by cross-referencing the type of injury with the sector of activity (Table 6).

We found a proportion of 13.59% of traumatic hand injuries in relation to the total number of patients seen in trauma emergencies. In 2008, the figure was 8.02% [1] . Very few studies have been carried out to determine the extent of hand trauma in Africa. SEYE et al. [2] , in 1994, found a frequency of 271 patients per year over 12 years. In the West, reliable statistics are available on the incidence of these traumatic lesions, as the management of hand disorders is well codified in well-defined structures with a correct archiving system. In France, the Réseau de Prévention Main de L’Institut Chirurgical de la Main et du Membre Supérieur (ICMMS) (Hand Prevention Network of the Surgical Institute of the Hand and Upper Extremity) has found a frequency of 15% to 40% of hand trauma among traumatic emergencies [3] . In other countries, such as Denmark, they account for 28.6% of traumatic injuries, or 3.7 per 100,000 inhabitants per year. [4] [5] [6] [7] [8] . Our figures fall far short of the reality, given that in Africa, hand injuries have a false reputation for being benign and healing without sequelae. Many patients don’t seek medical attention. Sometimes, they turn to bonesetters, and in most cases, the lesions are found to be residual, making treatment difficult.

There was a strong predominance of young patients (age range 21 - 30: 33.68%) and males (sex ratio 5.6/1). In Naïrobi, KAISHA et al. found an average age of 28.2 years [9] . They were joined by Hey et al. [10] , in Singapore, who found 88% were male, the majority aged between 20 and 30 [10] . For OBERT et al. [6] , hand trauma affects a young population (average age 31). The same is true for OZÇELIK [11] , SERINKEN [12] and SOROCK [8] , in Turkey and the USA, with male patients aged around 30 during their working lives [8] [11] [12] . This male predominance has also been found in Douala [13] and Antananarivo [14] , with a sex ratio of 3:1 and 9:1 respectively, in subjects in their 3rd decade of life, most of whom were victims of accidents at work [13] [14] . In our series, the most common circumstances for the occurrence of hand injuries were work-related accidents (47.08%), followed by fights (16.49%) and domestic accidents (15.46%). The literature review identified the most frequently encountered etiological circumstances. In decreasing order of frequency, these were work accidents, leisure accidents, domestic accidents, followed by fights and assaults [6] [8] [9] [11] [12] [14] [15] [16] [17] . According to a study by the European Federation of Hand Emergency Services, in 2002, 62% of hand injuries were due to domestic accidents, 28% to accidents at work and 10% to road accidents [3] .

Manual workers were affected in a statistically significant way (p = 0.000) during an accident at work. In the study by LANGLAIS [18] , they accounted for 96%. As shown by other studies [2] [9] [18] [19] [20] , the majority of injuries were sustained by males. Men are more likely to be involved in manual work, which is the most frequent source of accidents, whereas women are more likely to be victims of domestic accidents.

Risk factors incriminated in the occurrence of these accidents during work activities include the use of unsuitable equipment or materials, lack of training and concentration, inappropriate work environment, overwork, taking narcotics, as well as the physical and psychological state of the worker [1] [7] [21] - [27] . In developed countries, these injuries occur in leisure accidents (35%), domestic accidents (34%), work accidents (26%) and traffic accidents (15%) [4] [5] . Indeed, the resulting injuries and their after-effects have an impact on the socio-professional life of patients [28] . Their socio-economic repercussions, through the number and duration of work stoppages they cause, have led to the reinforcement of the system of protection in the use of work tools at company level. This is not the case in our countries, where no awareness-raising campaigns have been conducted in this area, as most of the population work in the informal sector and/or on their own account. In the West, accidents in the home are more numerous than those in the workplace, as the population makes extensive use of increasingly high-performance and often dangerous household appliances. These results support the theory that hand injuries are the preserve of young, active males. They represent the most numerous and active socio-professional strata, and are therefore the most exposed to accidents. With regard to the origin of our patients in relation to the care centers, most of them came from the different departments of Dakar, mainly from Dakar-Plateau, which accounted for 75.26% of patients. The rate decreases as one moves away from the city.

As far as emergencies are concerned, we note that patients consult us close to where they live or where the accident occurred. Although our hospital is one of the leading facilities for hand surgery, it should be noted that at present, other hospitals on the outskirts and in the regions have orthopaedic surgeons who can treat most hand injuries. Nevertheless, patients from Guédiawaye, Thiès and Rufisque all had complex hand injuries.

The right hand was affected in 58.76% of cases. The dominant side accounted for 56.5%, similar to the results of OGEMDI et al. [29] and LADJOUZI [30] , who found respectively 56.8 and 63.63% involvement of the dominant limb [29] [30] .

In view of these results, it is highly unlikely that the dominant hand is a significant precursor of the hand studied. However, PORAC et al. [31] found that the risk of hand trauma was the same for right- and left-handers alike. Unlike us, trauma in their series was most often noted on the dominant hand. This has also been found by other authors [15] [26] [29] [32] [33] .

Traumatic injuries to the hand are diverse and varied. In our study, osteoarticular lesions predominated with 36% of cases, compared with the results of African series where osteoarticular lesions predominated with 82.4%, 63.3% and 60% respectively for SEYE, RABEMAZAVA and FARIKOU [2] [13] [14] . These were mainly phalangeal fractures. Very few studies report injuries to the nail apparatus [34] , which accounted for 23% of all injuries in our study. We have individualized them within their own nosological framework, and they are most often associated with bone lesions. European series are more focused on manual workers [8] [12] [35] , table saws [36] and mountaineers [37] . In other cases, lesions are found after a domestic accident [38] . In the various reports, traumatic amputations and soft tissue injuries are more common [7] [8] [15] [36] [39] [40] [41] than osteoarticular injuries [4] [17] .

Open trauma was noted in 55.67% of cases. We found no articles specifically studying the ratio of closed to open lesions. Only RABEMAZAVA et al. identified 72 open fractures versus 43 closed fractures in 221 cases of osteoarticular lesions. Elsewhere, it was the nature of the lesions—fractures, dislocations or even lacerations [4] [7] [14] [15] —that was specified. We did not identify any statistically significant difference between the risk of having a closed lesion and that of having an open lesion, nor any study to date that might explain it. There was no significant difference between the right and left hands with regard to the risk of skin lesion, with 49.1% and 50.9% respectively (p = 0.000). On the other hand, most of the injuries were open, with 47.4% among power workers, 30.6% among precision workers and 21.9% among students. Closed injuries mainly affected the right hand. There was no correlation between circumstances and the occurrence of open or closed lesions. SERINKEN et al. found no correlation between profession, age, social status, sector of activity and type of injury in general [12] . MORENO et al. made the same finding [26] . On the other hand, we have noted that complex traumas are mainly found among forced labourers (71% of them), the majority being nail traumas (36.2%). Conversely, closed traumas were more common among precision workers (60.7%), mainly contusions (10.8%). Finally, students were more likely to suffer phalangeal and metacarpal fractures, which accounted for 42.1% of injuries observed (p = 0.00). However, it should be pointed out that although nail trauma remains dominant (23.2%), there is no significant difference between contusion (14.77%), phalangeal fracture (17.53%) and metacarpal fracture (13.75%).