There are many different chiropractic technique systems that have been developed. To our knowledge there is no current information available regarding which technique systems are the most effective in the management of specific musculoskeletal conditions. Developing studies to evaluate the effect of every technique system on every specific condition is not feasible at this stage. This survey describes the techniques commonly used by chiropractors in the treatment of specific spinal musculoskeletal conditions with the aim to help researchers make clinically relevant choices for future research.
Scope of practice
The majority of respondents primarily focus their treatments on musculoskeletal conditions and apply an evidence informed approach to their clinical practice (Table 2). Therefore, the scope of practice reported by the respondents is consistent with the focus of the survey. The positive attitude of many Australian chiropractors towards evidence based practice was also found in a study from Walker et al., where 78% of the respondents agreed that the application of evidence based practice is necessary .
Diversified technique was reported to be the most commonly used technique system amongst Australian chiropractors. The high frequency of use of Diversified technique is in line with previous studies from Australia and overseas -,,. A Canadian study from 2009 found that Diversified was the main technique used in private practice, followed by Activator and Thompson technique . In North America, Diversified technique is by far the most common (over 92%), followed by flexion distraction, Gonstead and Activator . In 1994 a large chiropractic job analysis was done in Australia and New Zealand . At that time Diversified was the most commonly used technique, followed by Activator, Gonstead, SOT, AK, Thompson and flexion distraction. In 2005, Walker et al.  conducted a telephone survey in Australia and New Zealand. In this study the most common technique system used by Australasian practitioners was Activator (49%), followed by Diversified (44%) and Gonstead (29%). However, additional categories of `manual adjustment' and `manipulation' were used in Walker's survey that may have skewed the results.
The survey results indicate that Australian chiropractors often include exercise prescription and soft tissue therapy in their treatments but rarely use electrophysical therapies. This is in contrast to chiropractic care in North America , but similar to European studies ,. French et al.  performed an observation and analysis study of Australian chiropractors. They found a high use of manipulative technique, soft tissue techniques and exercise prescription consistent with the results of this survey.
Technique selection for specific musculoskeletal conditions
Manipulative therapy (Diversified technique), soft tissue techniques and exercise prescription were reported as the most commonly used treatment techniques in the management of spinal musculoskeletal disorders. Instrument adjusting (Activator or similar) was commonly used in the cervical spine, however, use decreased in the thoracic and lumbar spinal regions. Table assisted drop piece and flexion distraction techniques were more commonly used in the lumbar spine. Small changes were noted in the frequency of use of different techniques between specific musculoskeletal conditions, however, the predominant differences were region rather than condition specific.
Diversified manipulative technique is the most frequent initial treatment of choice for the majority of musculoskeletal conditions surveyed. In 16 of the listed 18 conditions, it was reported to be used as the most frequent first choice of treatment. Conditions with a neural component such as: cervical disc syndrome (with radiculopathy); cervical central stenosis; lumbar disc syndrome (with radiculopathy); and lumbar central stenosis were associated with less use of Diversified technique as the first treatment choice. In these conditions more practitioners reported the use of instrument adjusting in the cervical spine and flexion distraction in the lumbar spine. It is unknown whether the increased use of instrument adjustment and flexion distraction in these conditions may be related to safety concerns or belief of increased efficacy. Instrument adjusting and flexion distraction are viewed as lower force techniques, however, no clinical evidence exists indicating that the use of these techniques is safer than Diversified technique . Further research to determine risk versus treatment benefit is important in these cases.
A higher use of instrument adjusting (Activator or similar) was reported for musculoskeletal conditions in the cervical spine compared to conditions in other spinal regions. Similar findings were reported in a British study where chiropractors reported cervical pain as the predominant reason for using Activator . Our data suggests an increased use of flexion distraction in conditions such as lumbar disc syndrome with radiculopathy and lumbar central stenosis. A review by Gay et al.  also reported that lumbar dysfunction was the main indication for the use of flexion distraction. In light of these data, controlled studies are needed to determine if instrument adjusting is more effective or safer than other treatments for cervical conditions and if flexion distraction is more effective or safer than other treatments for lumbar conditions.
Table assisted drop piece technique was rarely used for cervical and thoracic conditions, but there was an increase in use for lumbar and sacroiliac conditions. To our knowledge, no randomised trials evaluating the effectiveness of table assisted drop piece technique are available and evaluation of this technique in the treatment of sacroiliac dysfunction may be indicated.
Factors influencing treatment choice
Chiropractors may choose to use a specific technique system in certain conditions for several different reasons. As a result of clinical experience and therapeutic trial and error in similar situations, practitioners may have developed an understanding of what techniques work better with specific presentations. Practitioners may find one technique system easier to apply than others because of their own physical characteristics or the complexity of the technique system. In addition, they may have been guided by their education and apply technique systems to a degree which they were taught in their chiropractic course.
Practitioners might choose a certain technique system, based on their clinical experience in managing patients with a similar musculoskeletal condition. A trend was noted when chiropractic practitioners of more than ten years' of clinical experience were compared to those of less than ten years' experience. In general, the more experienced practitioners tended to use more instrument adjusting and soft tissue therapy, whereas, the less experienced practitioners tended to use more Diversified technique. Possible reasons may be that the more experienced chiropractors have found better results with these techniques or it may relate to the fact that these techniques are less physical demanding. Also, instrument adjusting is not taught in pre-professional courses in Australia, but can be learnt after graduation. Therefore, new graduate chiropractors may use instrument adjusting less frequently due to reduced exposure to this treatment modality.
Implications for further research
It is hard to determine which chiropractic techniques are most effective. To do this, randomised controlled trials (RCTs) have to be executed. Unfortunately, it is very difficult to provide a placebo treatment for a manipulation. RCTs comparing the clinical effectiveness of two different technique systems on specific musculoskeletal disorders may help to inform practitioners' treatment choices. However, reaching a conclusive musculoskeletal diagnosis in a clinical setting may limit the ability to perform this research. Subgrouping musculoskeletal disorders into those with and without neurological involvement would be more achievable in a clinical setting, and would capture the differences in preferred treatment technique found in this survey. As evidenced by our data and data from other studies -, a chiropractor often uses a combination of manipulative techniques and ancillary treatment methods in the clinical setting. Although this does not provide evidence of efficacy of a single technique, RCTs investigating a combined approach would more closely mimic clinical practice.
The data from this study can be used to inform future studies and direct formulation of research questions. After analysing our data we suggest seven future research questions (see `Proposed future research questions for major RCTs' list below) that might directly influence decision making in clinical practice for Australian chiropractors. These seven research questions have been formulated based on the trends we described in the above sections.
Proposed future research questions for major RCTs
Clinical effectiveness of Diversified technique in the management of any of our listed musculoskeletal conditions.
Clinical effectiveness of instrument adjusting (Activator or similar) in the management of cervical disc syndrome with radiculopathy.
Clinical effectiveness of instrument adjusting (Activator or similar) in the management of cervical central stenosis.
Clinical effectiveness of the flexion distraction technique in the management of lumbar disc syndrome with radiculopathy.
Clinical effectiveness of the flexion distraction technique in the management of lumbar central stenosis.
Clinical effectiveness of table assisted drop piece technique in the management of sacroiliac joint dysfunction.
Clinical effectiveness of soft tissue therapy and/or exercise prescription in combination with Diversified technique in the management of any of our listed conditions
The main limitation of this research is that of low response rate. Surveys were distributed through emails from the two main Australian chiropractic associations and it is impossible to know how many chiropractors actually received and read the emails. Therefore, true response rate, and assessment of potential non-response bias, cannot be determined. Non-response bias is of concern if only subjects interested in the subject complete the survey. The results of this survey were compared to demographic data from the chiropractic registration board and previous research to try and establish how reflective the respondents of this survey were to the chiropractic population as a whole. Demographic data was similar to survey respondents except for an increase in the number of respondents working in New South Wales with a decrease in those working in Victoria and an increase in the number of respondents from a younger age group. Scope of practice among survey respondents was heavily skewed to those treating muscular pain and dysfunction, possibly indicating respondant bias. However, previous research conducted by French et al.  also indicated that Australian chiropractic practice primarily focuses on the treatment of musculoskeletal pain. Therefore, this result may be reflective of the chiropractic population as a whole. There was also a high proportion of respondents who used Diversified as their primary therapeutic technique as opposed to other chiropractic techniques. However, similar trends are noted in previous studies done in Australia , and the United States , indicating that our sample population responded fairly consistently with other, larger scaled, studies. Although we do have some similarities between the survey responses and previously published data we cannot eliminate the possiblity of non-response bias skewing the results of this survey. Therefore, the results of this survey should be interpreted with caution as they may not be reflective of the Australian chiropractic population as a whole.
Epidemiological data was to be used to help formulate the list of musculoskeletal conditions included in the survey. However, data regarding the prevalence of specific musculoskeletal conditions presenting to chiropractic practices is lacking. There is some data available regarding presenting symptomatic regions ,,, but not related to specific musculoskeletal diagnoses. Therefore, selection of musculoskeletal conditions based on specific epidemiological data was not possible.
The survey instrument was not validated, however, it was based on questionnaires used in similar studies that focused on technique systems in general ,,. These questionnaires were reformed to suit our condition-specific questions. In addition, the survey was not exhaustive, with only five chiropractic technique systems included. Although the option was provided to select and specify any other technique system, the setup of the question may have influenced respondents to select one of the five listed technique systems. These five technique systems were chosen as previous research had shown them to be the main techniques used in Australia . Reviewing comments from practitioners who specified "other techniques" in the survey failed to demonstrate any consistent trends in additional technique systems used.
Recall bias may also be a concern in this survey. Practitioners may over- or under-estimate the degree that they use certain techniques for specific conditions. Although we cannot rule out recall bias we feel that the general nature of the questions asked limit this as a particular concern. The survey questions asked for preferred first, second and third treatment techniques rather than the frequency of usage of those techniques to reduce the effect of recall bias.
Lastly, it may be possible that the musculoskeletal conditions listed in the survey were interpreted differently by different respondents. The aim of the survey was not to test diagnostic abilities in the practitioners, but rather to gain information about which chiropractic technique they would use to treat a specific textbook condition. Gradations in severity of the conditions were not provided, nor were many other variables that may change decision making.