The life time prevalence of WRMDs among physiotherapists has been reported to be 68% in the United Kingdom [13], 55% [14] and 91% [8] in Australia, and 85% in Turkey [7]. Low back pain is the most common WRMD among physiotherapists [5-8,14] with career and annual prevalence of low back pain among physiotherapists in the United Kingdom being reported as 68% and 58% respectively [13]. In the United States, prevalence of low back pain among physiotherapists ranged from 45% [5] to 62% [6]. Mierzejewski and Kumar [9] found the prevalence of low back pain in Canada to be 49%, while Shehab et al [15] reported a 70% prevalence of low back pain in Kuwait.

Some research indicates that WRMDs among physiotherapists may be age related and also associated with professional years of experience. Bork et al [5] indicated that physiotherapists aged more than 50 years had the lowest prevalence of WRMDs, while others [7,9,13,16] reported that most physiotherapists first developed symptoms before the age of 30 years and that majority of these initial episodes occurred within five years after graduation. The physically demanding nature of the physiotherapy profession may contribute to the occurrence of WRMDs and result in a high prevalence. Elements of physiotherapy practice which have been suggested as risk factors include: treatments which demand repetitive movements or continuous bending, lifting/transferring dependent patients, responding to unanticipated or sudden movements by patients, performing manual therapy, restricted work place, understaffing, age and sex [8,10,14]. Scientific literature from various parts of the world has also reported significant association between occupational risk factors involving high repetition rates, excessive forces, and awkward postures and musculoskeletal disorders [17].

The questionnaire for this study was based on previous published surveys [8,14] but adapted for use among Nigerians. The questionnaire had two sections and contained 27 questions (see Additional file 1). Section A of the questionnaire sought information on the demographic characteristics of the respondents, their years of experience, work setting, work status and whether they have had ergonomic training or not. Its section B contained items on WRMDs, work factors and coping strategies. Respondents were asked whether they had experienced WRMDs that we defined as discomfort, injuries or pain due to their work and lasting more than three days in the last 12 months in any part of the body [14]. Respondents who indicated experience of WRMDs symptoms in any of the body areas were asked to choose the areas of disorder that they considered as the most significant and asked further questions about their disorder. Previous studies have shown the Nordic questionnaire to be valid for assessing WRMDs [20,21]

Our finding that there were more male than female physiotherapists in the survey is a reflection of the population from which our sample was drawn. This finding is contrary to the findings from previous studies that reflected more female than male physiotherapists [5-8,13,14]. This result is understandable since unlike in Europe and America, the physiotherapy profession in Nigeria is male dominated. Indeed, 62.3% of the registered physiotherapists in Nigeria are males [23]. The gender distribution of the respondents in our study is hence largely representative of the population of physiotherapists in Nigeria.

We observed a significantly higher prevalence of WRMDs among female physiotherapists with all the female physiotherapists in comparison to 86.3% of the males reporting WRMDs. Our finding is consistent with findings from previous related studies [5,7,13]. Borke et al [5] implicated the female gender as a potential risk factor for the occurrence of WRMDs while Glover et al [13] reported a higher prevalence of work related low back pain, neck pain, shoulder pain and wrist/hand pain among female physiotherapists. A higher but not statistically significant prevalence of WRMDs has also been reported among female Turkish physiotherapists [7]. Cromie et al [8] however reported a higher prevalence of WRMDs among male physiotherapists and attributed their finding to a greater usage of mobilizations and manipulations by male physiotherapists than their female counterparts in their study. It has been suggested that the usually higher prevalence of WRMDs in female physiotherapists may be related to their height and body weight which put them at a disadvantage during patients' treatment and/or transfer [5]. Also, women do have a higher prevalence than men for many upper extremity musculoskeletal disorders, even after controlling for cofounders such as age or work factors [24]. It is interesting however that the prevalence of WRMDs in our study was higher in individuals with normal body weight (94.6%) than obese ones (71.4%).

The 12- month prevalence of WRMDs among Nigerian physiotherapists was found to be 91.3%. This prevalence is higher than the 12-month prevalence of 58% reported by Glover et al [13], 40% by West and Gardner [14], 61% by Bork et al [5] and 62.5% by Cromie et al [8]. The only comparable findings in the literature were the life time career prevalence of 91% and 85% reported by Cromie et al [8] and Salik and Ozcan [7], respectively. The higher 12-month prevalence found in our study suggests that physiotherapy practice in Nigeria highly predisposes to WRMDs. This may be a reflection of the conditions under which physiotherapists practice in Nigeria. Physiotherapy practice in Nigeria, like in many other developing countries is largely bedeviled by unwholesome work settings, understaffing and lack of appropriate equipments including those as basic as standard plinths. This is beside the influence of peculiar cultural values of physiotherapists such as skills, relationships with patients and attitudes of caring and working hard that have been opined as making it difficult for physiotherapists to do their job in a way that minimizes the risk of WRMDs [18]. It should be noted however that the extent to which work contributed to the etiology of musculoskeletal disorders in participants in our study cannot be readily ascertained and is hence largely debatable. It is plausible that some of the physiotherapists in our study probably misconstrued all musculoskeletal disorders as WRMDs regardless of whether these were caused by work or not since the consequence of musculoskeletal disorders and WRMDs in terms of work absenteeism may be similar.

In this study, the low back was reported as the most common site of WRMDs among Nigerian physiotherapists, with a 12- month prevalence of 69.8%. Internationally, the prevalence of work-related low back pain ranged between 22% and 74% [8,13,25]. Our finding is consistent with those of previous studies that have overwhelmingly implicated low back as the body part most commonly affected by WRMDs among physiotherapists [5,7-9,13,14]. In the United Kingdom, the 12-month prevalence of work-related low back pain among physiotherapists was found to be 22% [13], while the prevalence varied between 22% [14] and 62.5% [8] in Australia. Bork et al [5] found the annual prevalence of WRMDs low back pain to be 45% in the U.S.A. Our finding may be a further reflection of the overall picture of the poor conditions of practice that may cause high prevalence of WRMDs among Nigerian physiotherapists.

The majority of the physiotherapists in this study were found to have experienced their first episode of WRMDs within five years of graduation. This is similar to the findings of the majority of studies on WRMDs among physiotherapists [5,6,8,9,13,14]. We also observed the prevalence of WRMDs to be higher among physiotherapists that were younger than 30 years of age. This finding is consistent with those of Salisk and Ozcka [7] in Turkey, Glover et al [13] in the United Kingdom, West and Gardner [14] in Australia, Mierzejewski and Kumar [9] in Canada and Bork et al [5] in the United States of a higher prevalence of WRMDs among physiotherapists younger than 30 years of age. Our finding in this regard is particularly important when viewed against the background of a higher mean age at graduation of physiotherapists in Nigeria compared to their counterparts in Europe, USA and Australia. Our finding hence suggests that physiotherapists in Nigeria may enjoy a shorter WRMD-free career life than their counterparts in other parts of the world. However, findings relating to the onset of injury need to be viewed with caution as it may be very difficult to ascertain the onset of WRMDs without a substantial recall bias.

The work factors commonly identified by physiotherapists in this study as contributing to the occurrence of their WRMDs in decreasing order of importance were: treating a large number of patients in one day, working in the same position for long and lifting or transferring dependent patients, and performing manual therapy techniques. Previous studies have similarly identified treating large number of patients in a day and working in the same position for long periods of time [5,8,14], lifting or transferring dependent patients [6-8,16] and performing manual therapy techniques [14] as the work factors most commonly found to cause WRMDs among physiotherapists. In our study, physiotherapists selected reaching or working away from the body and working with confused or agitated patients as the least important work factors to the occurrence of their WRMDs. It should however be noted that the work factors identified in our study were not specific to individual musculoskeletal disorder but rather cut across various musculoskeletal disorders. This is an important limitation of our study given that previous related studies have submitted that work factors are to some extent specific to individual musculoskeletal disorders. Thus, mobilization and manipulation have been identified as work factors to the occurrence of upper limb, neck, and upper back pain [8]; while performing the same task over and over [13] and lifting and transferring dependent patients [14] have been reported to be related to the occurrence of low back symptoms However, since physiotherapists in our study self- reported the work factors, their responses might have been a reflection of their belief rather than the actual contributions of the work factors to their disorder.

The most commonly adopted coping strategies among physiotherapists in our study were therapists modifying their position or the position of their patients, therapists selecting techniques that will not aggravate or provoke their discomfort, and therapists adjusting bed or plinth height. This finding is similar to that of Glover et al [13], which reported the four most important preventive strategies commonly adopted by physiotherapists in response to sustaining musculoskeletal disorder at work as: therapists adjusting plinth or bed height, therapists modifying their position or the position of their patients, obtaining assistance when handling heavy patients, and ceasing a patient's treatment if such treatment aggravates or provokes their symptoms. Further, most of the physiotherapists in our study would also change or modify a patient treatment in the face of their WRMDs thus suggesting that physiotherapists in Nigeria who had experienced WRMDs might have sometimes selected treatment methods for reasons other than the needs of their patients – their own comfort. This attitude may not augur well for the application of the principle of altruistic care needed for effective patient treatment and optimal recovery.

Despite the high prevalence of WRMDs among Nigerian physiotherapists, we found that the majority of the physiotherapists did not leave the profession and only a few changed their area of practice/specialty. Our finding is consistent with those of majority of studies that found that few physiotherapists will change their areas of practice [7,8,13] and majority will not leave the profession [5,8,9,13,14] as a result of WRMDs. While previous studies which were conducted mostly in developed countries explained their findings in the context of 'survival bias' developed during career [5,14], adaptation to injury [13], flexibility of work change within profession [8,14] and the culture of physical therapy [18], our finding may be suggestive of limited career-change option among Nigerian physiotherapists. This view is buttressed by our finding that 96.5% of Nigerian physiotherapists work full time and that only about a quarter had postgraduate training- an option which might have enhanced their choice of area of practice/specialty. Further, the economic vagaries and palpable financial insecurity in Nigeria may actually make physiotherapists in Nigeria to stay put within the profession despite its attendant high risk of WRMDs. The real reason or reasons why Nigerian physiotherapists do not leave the profession in spite of the high rate of WRMDs would however need to be further investigated by future studies.