Questionnaire development
We developed an initial set of questionnaire items in consultation with Murdoch staff members who taught cervical manipulation technique. An expert panel was then formed, who used a Content Validity Index (CVI) to ensure that the questionnaire was relevant to assess neck manipulation competency among chiropractic students [16, 17]. The expert panel consisted of seven chiropractors who teach neck manipulation at several Australian universities and one international university. The composition and size of this expert panel was congruent with guidelines that propose that the panel members’ professional backgrounds reflect that of the target population, and that the ideal number is between six to twelve members [16, 17]. Every panel member evaluated each item using four categories: not relevant, unable to assess relevance without major revision, relevant but needs minor alteration, and very relevant. A value of one was assigned to the “very relevant” and “relevant but needs minor alteration” categories, whereas a value of zero was assigned to the other categories. The I-CVI for each item was derived by summing the values for each rater and then dividing by the number of raters. Items were retained if the CVI exceeded 0.79 [16, 17]. After the initial expert panel evaluation and feedback, the pilot version of the questionnaire was expanded considerably in the domains of rating expertise. In the second round of evaluation, the I-CVI for individual items ranged from 0.86-1.0 and all items were retained. The S-CVI, which is the proportion of items rated as either “relevant but needs minor alteration” or “very relevant” by all raters, was 0.94.
The final questionnaire comprised five assessment criteria, of which three contained several sub-criteria. The five assessment criteria were:
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1)
Patient and practitioner positioning
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Is the patient positioned correctly?
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Is the headrest in the correct position?
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Is the practitioner positioned correctly?
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2)
Joint pre-tension
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3)
Contact points
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Is the contact point on the patient correct?
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Has the correct side of the patient been contacted?
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Is the contact on the practitioner’s hand correct?
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Is the practitioner’s indifferent/stabilising hand correctly positioned?
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4)
Vector of correction/line of drive
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5)
Procedure
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Is the amplitude of the thrust applied sufficient to address the fixation?
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Is the speed of the thrust applied sufficient to address the fixation?
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Was the demonstrated manipulation/adjustment executed safely?
Sample
All students enrolled in the fourth of the five year chiropractic program at Murdoch University during 2014 (N = 41) were invited to participate. Paper copy information notices were distributed in the first lecture of 2014, and a non-teaching staff member delivered an information session and provided an opportunity for students to raise questions about the study to inform the consent process. Students were informed that participation was entirely voluntary, and electing to participate or not participate, would not affect their relationship with University staff in any way. The Murdoch University Human Research Ethics Committee approval number was 2013/200. All 41 students initially invited to participate provided consent to have their results included in the final analysis.
Randomisation and blinding procedure
A staff member, not involved with group allocation, used a random number generator to generate a randomisation list. The group assignment was placed in sequentially numbered, opaque, sealed envelopes. After obtaining informed consent, staff not assessing neck manipulation competency opened the envelope and allocated students to one of two groups: usual learning or mannequin learning. Staff assessing neck manipulation competency, and undertaking data entry and analysis were blinded to group allocation.
Due to the nature of the study it was not possible to blind students to their group allocation, however at all times the assessor remained unaware of the group randomisation. Students are aware that under Australian Law, unless they are a registered practitioner with the Australian Health Professions Regulatory Authority, performing cervical spine manipulation outside of a recognised training program is prohibited [18]. Thus it is unlikely that students practised cervical spine manipulation outside of their usual teaching times.
The mannequin
The cervical mannequin is known as “Flexi-man” and is shown in Figs. 1 & 2. Fleximan has been developed and manufactured by Dr. Timothy Young, Chiropractor [19]. The mannequin consists of a flexible imitation of shoulders, neck and head made of a pliant “rubberised” material. The weight of the mannequin is 4.8 kgs with the specific head weight unknown, however a proxy head weight was 3.2 kgs. This proxy weight was established by laying the mannequin prone with the head recumbent on weight scales. The mannequin was designed to allow students to set up, place contacts and deliver a thrust in a line of drive of their choosing. It does not however allow for pre-manipulative tension. The mannequin is a stylised human facsimile and is not designed to mimic a human specimen. It does not have the variability of human subjects receiving manipulation, for example height, weight, and tissue compliance. The makers state that the mannequin is best used in the introductory phases of training [20].
Educational interventions
The usual learning group practised neck manipulation techniques on each other under supervision consistent with the description provided in the introduction to this article. This learning approach has been used since the inception of the Murdoch University chiropractic program in 2002. The mannequin learning group practiced the neck manipulation techniques on a mannequin with a flexible neck, once again under supervision. The mannequin learning approach was a novel method not previously used at Murdoch University. Each group received three, two hour weekly training sessions in the performance of a commonly used cervical spine manipulation technique referred to as the index pillar push [21]. During the weekly training sessions and to ensure that the assessor remained blinded to group allocation students were supervised by academics not involved in the assessment of the students. The supervising academics provided each student with regular personalised feedback relating to their performance of the required technique during the weekly training sessions. After the third weekly training session, all members of each group crossed over and undertook three additional training sessions using the alternate method. The flow of the study is displayed in Fig. 3.
All fourth year students who participated in the study had already received training in neck manipulation in the third year of the program but there is a long summer break between third and fourth year so skills usually diminish. On the first week back at University, a staff member experienced in manipulation assessment who was blinded to group randomisation, assessed the student’s performance of the index pillar push procedure at baseline on the mannequin (immediately before the first training session) and then again at four weeks, and eight weeks, by using the validated instrument of measurement.
Assessing student performance of the index pillar push technique involved the assessor requesting the student to perform the technique on both the left and the right hand side of the mannequin. Each student was allowed to perform the technique once on both sides, while the assessor graded their performance.
The maximum total score on the validated questionnaire is 100 %. In order to pass the assessment a student must achieve a minimum score of 69 % overall.
Each of the five identified assessment criteria are considered critical to the successful performance of the required technique. If a student fails to perform one of these five assessment criteria adequately the student is awarded an overall score of 69 %. Should the student fail to perform two of the five assessment criteria adequately they are awarded a score of 49 %. Less than satisfactory performance of three criteria results in a score of 29 %. Inadequate performance of four assessment criteria results in a score of 19 % being awarded to the student. If all five assessment criteria are unsatisfactorily performed or the student is unable to perform the required technique, the student is awarded a score of zero.
Statistical analysis
All data were entered manually into SPSS v.21, cleaned and checked for implausibilities. A chi-square test was used to examine differences between groups for the proportion of students achieving an overall pass mark at baseline, four weeks, and eight weeks.