Data Collection

3.2.1 Non-pathological Subject Recruitment

The recruitment of NP volunteers was approved by the Research Ethics Committee for Wales and Cardiff University Health Board. Volunteers were recruited via email and poster advertisements throughout Cardiff University and the wider South Wales community. The criteria for inclusion in the study as a NP volunteer was as follows:

• No self-reported OA, or pain in the foot, ankle, knee, hip or back. • No known difficulty performing ADLs.

• No history of musculoskeletal conditions which required medical treatment e.g. ligament or meniscal tear.

• No other musculoskeletal, neurological or visual condition which might affect the way they move.

• An ability to give informed consent.

Any volunteers who expressed an interest in participating were given an information sheet. If the volunteer understood the information sheet and was happy to proceed, they were asked to sign a consent form.

3.2.2 Osteoarthritis and TKR Patient Recruitment

The recruitment of NHS patients with severe osteoarthritis was approved by the Research Ethics Committee for Wales and Cardiff and Vale University Health Board. These patients had all been listed for TKR replacement surgery.

The criteria for inclusion in the study as a patient volunteer was as follows: • An ability to walk 10m without a walking aid.

• An ability to give informed consent.

• No unrelated musculoskeletal, neurological or visual condition which might severely affect the way they move.

Before taking part in any aspect of the study, patient volunteers were given a patient information sheet. If the patient volunteer was still interested in taking part, they were asked to sign a patient consent form.

3.2.3 Gait Assessment

The gait analysis protocol matched that described by Watling (2014), and is, therefore, shall for conciseness only be described in brief. Further information and rationale behind the marker placement procedure is given within Section 4.2 .

Calibration - Before the volunteer arrives, the infrared cameras were calibrated such they could calculate their position and orientation relative to one another. Part of this procedure involved the definition of the origin and orientation of an orthogonal global coordinate system (GCS). The GCS was defined by placing an L-Frame, where the long hand of the frame represents the x-axis, the short hand the y-axis, and the vertical and mutually orthogonal axis is called the z-axis. The definition of the GCS defined the coordinate system within which all the data was then described by the camera system.

With the L-Frame in place, the camera system was then calibrated by waving a calibration wand; which contained two markers, through the intended volume of capture. The camera wand was passed through the volume for 45 seconds, as each camera recorded the movement of the two markers relative to the L-Frame. The cameras match the identified trajectories of the two markers, in order to calculate the disparity between their individual views (how differently the markers of the wand and the L-Frame appear within their 2D view). This measures disparity across the frames of the calibration trial were used to calculate the position and orientation of each camera relative to the GCS. The 3D coordinates of the markers are reconstructed by the multiple cameras, and a residual error is calculated which reflects the discrepancies between these 3D reconstructed points. If cameras showed residual errors greater than 1mm, the calibration procedure was repeated.

The position of the force platforms relative to the GCS was calculated by using two metal plates with markers attached, which enabled the calculation of the 3D coordinates at each corner of the force platform. This is discussed further in Section 3.3.4, and shown in Figure 3.4. This step crucial in identifying accurate COP coordinates, and hence calculating knee kinetics.

Informed consent – The participants were given an information sheet at least 48 hours before their first assessment, which explained the purpose of the study, what would be expected from them, and how the data would be anonymised and stored. Once it was established that the participant has read and understood the information sheet, they were asked to sign a consent form, which was signed by one of the lead researchers.

Questionnaires: The participant was asked to fill in relevant questionnaires regarding their knee pain and function. Additional questionnaires were added during the course of the study, following ethical amendments, which are described further in Section 5.3.3.

Clothing: The participant was asked to change into suitable clothing, having been advised within the patient information sheet to bring a loose-fitting pair of shorts and t- shirt. The assessment was carried out without footwear.

Anthropometrical measures: Height, weight, knee width, depth and knee girth measurements were taken. The measurement of height and weight is important for both the calculation of BMI, but also the normalisation of joint moments and GRFs. The added anthropometrical measures of knee width, depth and girth followed the protocol of Jones (2004). The anthropometrical measures were included in the final classification presented by Jones, and hence were considered in order to compare initial classifications within Section 3.6.1.

Assessment preparation: Retroreflective markers were attached to the subject using hypoallergenic wig tape. The full marker set is discussed in Section 4.2.1. For several subjects, EMG analysis was also performed however this data isn’t presented in this thesis. The placement of electrodes didn’t affect the marker locations, therefore it is

assumed the addition of EMG didn’t affect the calculation of kinematic and kinetic parameters.

Assessment of gait: Participants were asked to walk barefoot at a self-selected pace over a 10m walkway. The force platforms were located within the middle third of the walkway. If clean force platform readings weren’t recorded, the participant was sometimes asked to start slightly further back, and then the measurement was repeated. This whole process was repeated until there were at least six clean force platform readings for each leg. The participant was not made aware of the existence or location of the force platforms; however, they may have been conscious that something was different about this area of flooring. This is discussed further in Section 7.1. Following the assessment of gait, the subjects were also asked to perform other ADLs such as stair-climbing and sit-to-stand. This data, however, is not presented in this thesis. For further information, the reader is directed to Chapter 2.3 of Watling (2014), within which a comprehensive description is provided.