Reliability and Validity of Lower Limb Biomechanical Assessments: Can You Trust Someone Else’s Work?
The use of lower limb assessments in podiatric practice is an essential element when determining contributing factors to a current complaint and when monitoring the success of an individual’s management plan. What we were taught during our educational years through university and subsequent CPD courses gives a solid base on how “best” to subtract information from patients through open and closed ended questions and which tests/assessments are most appropriate. But what do these figures mean?
And in a world where there is an increasing number of practitioners working across multiple practices through contracting, locum and employment based agreements; how accurate can this number be when re-measured by a colleague?
In this article we look at a number of commonly performed assessments by podiatrists and their reliability, validity and inter-practitioner measurements.
Ankle Range of Motion
The assessment of ankle joint ROM is primarily completed in a weight bearing position, “knee to wall test”. In a research project by Bennell et al 1998, four practitioners of varying experience were tasked with measuring thirteen health individual’s ankle joint ROM. The two measurement being assessed were; distance of the first toe away from the wall when performing a lunge (knee touch wall) and the angle of the fibula in relation to vertical.
Inter-rater Reliability: There was no significant difference in the mean measurement of centimetres from the wall by raters. However, there was a significant
difference in the measurement of angle (p=0.001) between one rater and the other three, a mean difference of 4deg.
Intra-rater Reliability: There was no significant difference between raters for either the measurement to wall or measurement of angle between raters.
Conclusion: The weight-bearing lunge test can be complete reliably by the same practitioner or multiple practitioners with confidence of receiving comparable results.
The use of the word pronation has been thrown around a lot in the past and was largely based on the idea of a sub-talar neutral foot position brought to light by Root et al in the 1970’s. Since that time the education system has brought in changes to the base biomechanics discussed in that article by adding measurement tools such as the Foot Posture Index which was utilized in pointing out that very few people meet Root’s criteria of what constitutes a normal foot type and that majority of people are slightly pronated.
Conclusion: There is no agreed method in the measurement of pronation. Those which have been tested for reliability have shown inter-reliability to be poor – moderate at best. Additional questions need to be evaluated as to whether static foot posture can be correlated to dynamic gait as current evidence is not supportive of this theory. Similarly, the mindset behind the movement of pronation has been shifted as we begin to understand the individual’s tolerance to body stressors in contrast to a once evil motion.
3D Gait Analysis
Although very much still specific to laboratory testing 3D gait analysis is beginning to make its presence felt in both the public and private sector of the allied health fraternity. However, measurements and diagnosis made on account of those measurement are only useful if they display adequate reliability. One of the primary issues with the use of a 3D gait analysis system is the protocol which is required and the human error which takes place. One such error is the positioning of markers on identified anatomical land marks.
Conclusion: 3D gait analysis has a high reliability for the kinematic parameters in the sagittal and frontal planes of the ankle, knee and hip. However, poor reliability is seen when viewing the hip and knee in the transverse plane and the pelvis in all three planes.
The biomechanical assessment as a whole is used within both private and public health systems. The assessments which take place in these identification tasks have not been completely agreed upon. However, many of those which are used have been found to have quite poor reliability between assessors. Although these assessments are considered to be mainstream within the podiatry community, one must ask the question that if this continues and no protocol or substantial evidence is produced to contradict these findings then how long will these assessments be considered acceptable in an evidence based medicine society.
Below is a summary of the findings regarding the most common biomechanical assessment tools.
Limb Length Discrepancy = Good Reliability
Angle of Gait = Good Reliability
Base of Gait = Good Reliability
Manual Muscle Testing = Good Reliability
Ankle Laxity = Good Reliability
STJ Positions = Poor Reliability
STJ Neutral = Poor Reliability
First Ray ROM Qualitative = Poor Reliability
First Ray ROM Quantitative = Poor Reliability
FF to RF Relation Goniometer= Poor Reliability
FF to RF Relation Visual = More Reliable
In addition to Biomechanical Assessments, Physiological Assessments also take place in a podiatry consult and are most important in developing a management plan. This is especially important in the treatment of patients with chronic lifestyle disease such as Type 2 Diabetes or Peripheral Vascular Disease. Many of the Neurological tests have been found to have a fair inter-rater reliability, more specifically tests of sharps processing, vibration processing and joint position sense. Both Ankle Reflex Assessment and Monofilament testing have been found to have moderate inter-rater reliability.
Pedal Pulses Palpation have been found to have fair to substantial inter-rater reliability. It should be noted that all these test have potential to change how reliable they are based on the time available to a practitioner. If more reliable assessment protocol was developed there may be justifiable circumstances to extend consult times in order to provide more meaningful assessment results.
Until Next Time
Bennell, K., Talbot, R., Wajswelner, H., Techovanich, W., & Kelly, D. (1998). Intra-Rater and Inter-Rater Reliability of a Weight Bearing Lunge Measure of Ankle Dorsiflexion. Australian Physiotherapy, 175 – 180.
Griffiths, I. (2012). Overpronation: Accurate or Parachronistic Terminology. SporteX.
Jarvis, H., Nester, C., Jones, R., Williams, A., & Bowden, P. (2012). Inter-Accessor Reliability of Practice Based Biomechanical Assessment of the Foot and Ankle. Journal of Foot and Ankle Research.
Stief, F., Bohm, H., Michel, K., Schwirtz, A., & Doderlein, L. (2013). Reliability and Accuracy in Three-Dimensional Gait Analysis: A Comparison of Two Lower Body Protocols. Journal of Applied Biomechanics, 105 – 110.
van Gheluwe, B., Kirby, K., Roosen, P., & Phillips, R. (2002). Reliability and Accuracy of Biomechanical Measurements of the Lower Extremities. Journal of the American Podiatric Medical Association, 317 – 326.
Wrobel, J., & Armstrong, D. (2008). Reliability and Validity of Current Physical Examination Techniques of the Foot and Ankle. Journal of the American Podiatric Medical Association, 197 – 206.