Does clinical testing tell us much about functional performance? The Thomas test.
One of the topics that regularly comes up in our courses is how relevant are more static/clinical tests to our everyday dynamic and function related movements. We have decided to address this in this blog.
We also have a special treat. A sneaky link to Cor-Kinetic founder Ben Cormack's new article in July's Sportex Medicine *Click Here*
This is essentially a clinical vs. functional model comparison. A course participant once said traditional tests tell him all he needs to know about how people move, specifically the Thomas test. Obviously this is an anecdotal comment but the question is, does a more scientific viewpoint back this up?
The answer to the question "Should we still be using the Thomas test?" is probably not if you want to know how well people move when away from the treatment table.Schache et al in the British Journal of Sports Medicine performed a relevant study in 2009. It looked at the “Relation of anterior pelvic tilt during running to clinical and kinematic measures of hip extension”
Their objective was
“To assess the relation of anterior pelvic tilt during running to peak hip extension range of motion measured during running and hip extension ﬂexibility measured clinically”
They used the widely used modified Thomas test to clinically assess hip extension while dynamic assessment was performed using motion analysis software.
The conclusion the team carrying out the research came to was
“Static hip extension ﬂexibility, measured using the Thomas test, was not found to be reﬂective of these dynamic movements (running). The ability for clinicians to interpret the results of the Thomas test with regard to the sagittal plane movement patterns of the pelvis and hips during running may therefore be limited”
They also add
“As a result of the ﬁndings from this study and the work of others, it is advised that clinicians need to be extremely cautious about making predictions about the dynamic sagittal plane movements of the pelvis and hips based on the outcomes of the Thomas test”
This research paper is fairly emphatic that the correlations between static and dynamic measures of hip extension are low, and any use of the static measure to ascertain a dynamic measure is a “prediction”
What happens dynamically and functionally is not a simple reflection of what happens on a treatment table. Often people say “it works fine for me” or “so and so uses it so I use it” Are these good enough justifications in the face of more scientific evidence? We would suggest no. Just because you do something currently or have been taught a clinical methodology does not mean that we should not explore other assessment methods that pertain to functionality.
Lets have a look at some more science. Mcgill and Moreside in their paper "Improvements in hip flexibility do not transfer to mobility in functional movement patterns" in the journal of strength and conditioning in 2013, looked at the transferability of increased passive hip ROM to functional movement patterns.
“These results indicate that changes in passive ROM or core endurance do not automatically transfer to changes in functional movement patterns”
Not only do static, passive clinical tests seem to have low correlation but also passive exercises/stretches to improve dynamic hip ROM. Both are regularly used in clinics the world over but with seemingly little effect in assessing or changing our movement. Are we “asking the right questions for the right answers?” One reason for both pieces of research showing little correlation from the static to dynamic scenarios is that they are differing motor patterns. We often look at movement as being local structure (bone and tissue) based. It is becoming more apparent that specific movements are just that, specific, and controlled by the brain rather than being limited by local tissue length or structural orientation.Our brains work on a memory prediction model that uses feedback from the sensory systems such as the proprioceptive, visual and vestibular to auto associate stored movement patterns according to the situation. These systems will recognize visual horizon, orientation against gravity, joint compression, angle and torque, tissue tension and length. All these factors make dynamic movement very different from clinical testing therefore eliciting a very different efferent response, in terms of motor pattern, from the system.
Controlling our centre of mass (COM) during dynamic movement also provides a huge challenge to the body that cannot be recreated with a prone clinical environment. Add in balance and speed variables and we can see the highly specific nature of movement. On a simple biomechanical level as soon as we step away from the table we also add in the component of translation as well as rotation to movement. This is something that is hard to recreate on a treatment table. This added movement variable would also create changes in feedback and motor control.In fact Schache et al suggest the lack of correlation between static and dynamic hip extension.
”may be determined by complex dynamic neuromotor patterns rather than static ﬂexibility alone”Flexibility is context dependant because it is controlled efferently through the Gamma motor neuron system and intrafusal fibre (muscle spindle) gain. This in turn drives the Alpha motor neuron to operate our extrafusal (Skeletal muscle) fibres. Flexibility or stiffness levels in a movement are a brain output that relies on the context of what is being received through input of the sensory systems. Flexibility is not a skill in itself, and therefore should not be trained as such, but a component of successful movement. We need to be able to achieve the right amount at the right time in the right movement.Mcgill and Moreside also suggest
“training and rehabilitation programs may benefit from an additional focus on 'grooving' new motor patterns if new found movement range is to be utilized”
If we are to do this we must incorporate the most authentic patterns possible to ensure crossover. What this does not mean however is that input needs to always be functional but at some point functionality has to be addressed to ensure maximal motor pattern exposure for storage and recall from the motor cortex.
One of the most valuable measures that can taken our opinion is the difference between what happens passively in terms of ROM and how much of that range can be accessed within a more functional situation.
One of the tough things to find is an objective measure of a subjective creature. Variations in motor pattern strategies and structure mean that literally no two people operate in the same way. This is similar to the fact we do not look or talk the same and have variations in height, foot size and width. The question is does median data reflect actual human structure and operation? The subtalar (STJ) joint is a great example of this with multiple variations in both structure and function. This means very few people correlate to median STJ axis location with a wide variation of location in experimental studies and therefore variation in ‘normal’ foot function (Manter 1941, Kirby 2001, Lundberg 1993).
A number of pathologies related to deviations from this ‘average’ or median have been hard to consistently prove as causative. An example of this would be knee pain (Powers 2002, Hetsroni 2006)
When we compare the individual against a specific set of biomechanics, such as gait for example, we have to be careful in blaming any deviation from objective median data for a cause of pain. This deviation more than likely is just a personal variation.
Schache et al also found:
“Peak hip extension ROM was found to have a positive correlation with relative leg length. This meant that subjects with increased relative leg lengths tended to run with reduced peak hip extension ROM. This may well be a product of having different sized people running at the same absolute velocity on a treadmill”
So the subjective natural structural variation of human beings has an effect on the objective data we may compare them against. This is without factoring in the complexity of different learned motor patterns, running styles and previous injury history.
Schache et al in their testing state:
“it is apparent that the sagittal plane movement patterns of the pelvis and hips differ across a group of subjects running at the same speed"
At Cor-Kinetic we look more at the comparison of the system against itself e.g. left Vs. right. The variation between segmental capabilities, especially in cyclical activities such as running, in an integrated system may provide more clues to increased workload and avoidance strategies of the brain and body than objective comparisons of a median ROM from the subject. The same would be true of segmental contributions within a throw or a swing. If one part, especially a large resource such as a hip, does not contribute then does another part have to contribute more. This could lead to real or perceived tissue threat. The body will achieve the task desired in any way that it can, generally the path of least resistance.
If my left hip has much larger ROM and quality of motion during segmental assessment than my right then this will create asymmetrical motion and possibly increased actual or perceived stress/threat to the system. Now we know asymmetry is a normal but how much asymmetry presents a problem? When does our personal variation in movement become a limitation? Again it is hard to be objective in a subjective situation that is dependent on the threat assessment or stress load toleration of the individual.
Cor-Kinetic use a set of functional criteria to help us create the most authentic environment possible to be able to “ask the right question for the right answer”. This means to try to elicit the response from the brain that correlates to the movement being tested and helps us formulate the best treatment strategy. An ability to assess using functional criteria means that we have vital pieces of information about the individual for increased treatment success. Objective injury prediction has proved hard to come by.
Functional criteria include:
Proprioceptive authenticity – Biomechanics/movement patterns
Hetsroni et al, A prospective biomechanical study of the association between foot pronation and the incidence of anterior knee pain among military recruits. British Editorial Society of Bone and Joint Surgery doi:10.1302/0301-620X.88B7.
Jundberg A, Svensson OK: The axes of rotation of the talocalcaneal and talonavicular joints. Foot 3: 65, 1993.
Kirby K. Subtalar joint axis location and rotational equilibrium theory of foot function. J Am Podiatr Med Assoc 91(9): 465-487, 2001
Manter JT: Movements of the subtalar and transverse tarsal joints. Anat Rec 80: 397, 1941.
Moreside J, Macgill S. Improvements in hip flexibility do not transfer to mobility in functional movement patterns. J Strength Cond Res. 2013 Apr 15
Powers et al. Comparison of foot pronation and lower extremity rotation in persons with and without patellofemoral pain. Foot Ankle Int. 2002 Jul;23(7):634-40.
Schache A et al, Relation of anterior pelvic tilt during running to clinical and kinematic measures of hip extension. Br. J. Sports Med. 2000;34;279-283