The acknowledgement of quadriceps inhibition as a complicating factor in knee joint pathology is pretty much unquestioned in routine clinical practice.  This is evident by the standard  prescription of inner range quadriceps exercises as part of any post operative knee  regime and also cases of knee pathology that do not require surgical intervention.  My views on the appropriateness of inner range quadriceps as a primary strategy for quadriceps re-education are well known and have been discussed in previous posts (see Terminal Knee Extension) but suffice to say that I am not a big fan as I think there are more superior choices of exercise.

Compensatory Movement Patterns

In this discussion I want to review some of the compensatory movement patterns  observed clinically which appear to be the result of poor quadriceps functioning:

1. Impaired terminal knee extension

-  is the most obvious example and needs no further expansion here.

2. Compensatory hamstring hyperactivity

- this can be indicated by a persistence of hamstring tightness even when routinely stretched, indicative of an increased recruitment strategy.  It may appear paradoxical but the literature is full of detail on quadriceps / hamstring co-activation (particularly the ACL rehabilitation literature). Not surprisingly the reciprocal activation of hamstring / quadriceps recruitment is not an on-off mechanism but a graded degree of simultaneous tension – consistent with all joint requirements for stability. It may be that the compression produced by hamstring activity is a compensatory strategy for compromised quadriceps contribution?

3. Hamstring dominance in active straight  leg raise test

- the active straight leg raise test has been utilised as a measure of pelvic and groin dysfunction can also yield useful information regarding hamstrings / quadriceps activation.

I modify this test by bringing the patient into a straight leg raise position just short of hamstring tension and then request an active hold in this position.

Therapists can then observe two things:

A). A loss of terminal knee extension when under active control or

B)  Determining the site of predominant muscle activity (asking the patient to report their predominant area of perceived effort) which in this situation will often point to the hamstrings.

Because the position of the test is short of full hamstring tension one cannot deduce that this perception of increased hamstring tension is due to a lack of elasticity.

4. Compensatory trunk flexion

in an attempt to maintain the length / tension relationship of the quadriceps.  This is usefully measured in sitting with the establishment of a lumbar lordosis in an upright-seated alignment, feet off the floor.  The patient is then asked to extend the knee.  The frequent observation in this test is for the pelvis to posteriorly rotate producing trunk flexion.

In order to determine if this is a result of hamstring restriction or lack of active quadriceps control the therapist should try to passively extend the knee at the point at which the pelvis starts to posteriorly rotate.  Increased mechanical resistance indicates posterior leg tightness; greater passive range indicates inner range quadriceps inhibition compensated by posterior pelvic rotation.

5. The hamstring – gastroc paradox

- this is a concept we have touched on before and one not frequently discussed in clinical circles – although sometimes alluded to in gait analysis.  The crux of this theory is that the gastroc soleus complex acts with reversed origin /  insertion activity with the ankle as the fixed point.  Gastrocnemius contraction coupled with that of the hamstring produce a combined force, which tends to extend the knee.

In biomechanical terms this is the old ” parallelogram of forces” rule where two muscle groups crossing a joint from above and below act in a combined manner to extend the joint.  This again can be tested clinically by utilising a stance position superimposing a ¼ – ½ range squat on the front leg.  Palpation of dominant muscle activity is one way to try to determine predominant muscle activity and of course verbal feedback on dominant site of perceived effort is another.

In a previous discussion’s on extensor chain function we looked at the interaction between hip extension, knee extension and ankle plantar flexion as part of the basic propulsive mechanism.  Obviously disturbances in the synergies of these primary muscle groups will compromise the efficiency of this movement pattern.  The clinical challenge is to determine the site of increased stress and the mechanism of overload within the system. So many patients we see demonstrate an “Apropulsive (without propulsion) gait due to compromise of the extensor chain. As clinicians we need to be alert to recognise these mechanisms.

what observational gait parameters would give us clues about lack of propulsion in walking?

Enjoy the clinical challenge.

David

© David for PhysioDigest - an educational resource for the musculoskeletal rehabilitation community, 2009. | Permalink | 2 comments | Add to del.icio.us
Post tags: Biceps femoris, clinical testing, functional adaptations, functional movement, functional movement testing, hamstring / gastroc paradox, hamstring /quadriceps co-activation, Hamstring Flexibility deficits, hamstring rehabilitation, Hamstring strain, inner range quads, knee extension, knee stability, movement patterns, muscle hyperactivity, quadriceps, Semimembranosis, Semitendinosus, static quads

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The link between hamstring strains and poor core stability is frequently casually referred to in rehabilitation and strengthening conditioning literature.  In fact it appears that there is no injury these days that is not associated with impaired “core stability”!

Has it taken over from excessive pronation as the ubiquitous explanation for intrinsic overuse injuries?

However, rarely do we see discussed the postulated mechanisms between impaired trunk control and potential hamstring overload. Here we will consider these hypotheses, the clinical testing methods and rehabilitation strategies to address these functional control deficits.

Mechanism of hamstring overload in “core” instability.

The basic premise of impaired trunk controls involvement in hamstring overload is that compromised proximal trunk control (muscular control above the pelvis) leads to a compensatory overstrain of muscles more distant in the chain, in this case muscles attaching to the lower end of the pelvis.  The analogy of a triangle standing upside down is a useful visual concept to explain this phenomenon.  In this situation we have the hamstrings posteriorly and the quadriceps anteriorly acting with the knee as a point of fixation and trying to balance the pelvis in an antero-posterior direction, almost like reins horse riding.

Importantly the control requirement is not entirely in an antero-posterior direction i.e. a sagittal plane but is in fact all 3 planes of motion:

Sagittal Plane

Coronal Plane

Transverse Plane.

However, it is easier to consider in each individual plane and build up the elements.

Simultaneous Concentric & Eccentric Loading

So the concept of excessive hamstring activity in order to balance the pelvis “from below up” is complicated by the fact that the hamstring muscle group crosses two joints – namely the hip and knee and in many sporting situations there are  simultaneous but different movements occurring at the hip and knee.  This is thought to predispose the hamstrings to alternating patterns of concentric and eccentric activity which maybe required simultaneously depending on the position of the respective hip and knee.

Primary & Secondary Hip Muscle Function

The situation is further compounded by the frequent clinical observation of impaired hip joint extension function i.e. inhibition of the prime one joint hip extensors- gluteus maximus in particular.  Vladimir Yanda described this many decades ago as part of the “cross pelvic” syndrome and although this was reported in a context of tight hip flexors causing secondary gluteal inhibition, the clinical observation in my experience is just as frequent in patients without tight hip flexors – (as measured by Thomas test).

So What?….

So the practical implication of this scenario is an increased loading through the hamstrings by combining both a stability and a mobility challenge.  If we explore this further in terms of functional consequences for muscle recruitment this is often evident as a poor coordination of hip extension (as measured in Yanda’s prone hip extension test).  Here the prone patient is asked to extend the hip an inch off the supporting surface and the clinician observes for the pattern of motion.  First one is looking for the timing of contraction between glutes and hamstrings on the lifting leg with the hypothesis being that the gluteus maximus should initiate the hip extension pattern followed closely by the hamstrings.  In regards to the torso contribution, the proximal pelvis needs to be stabilised in order to allow the 15 to 25kgs of leg to be lifted.  In the presence of  hamstring substitution for gluteus max and compromised trunk control this leg extension is often accompanied by a hyper- lordosis of the lumbar spine and then associated anterior pelvic tilt.  This represents a shift in compensation above the pelvis where the movement of hip extension is enhanced by excessive contribution of lumbar lordosis and paraspinal muscle activation.  A critical point to bear in mind with this movement pattern is that lumbar lordosis associated with paraspinal hyperactivity has the complicating effect of relative inhibition of the anterior abdominal wall, which perpetuates the cycle of global core instability.

Clinical Solution

Previous posts outlined the sequence of progressions for proximal trunk control in this plane.  I don’t need to reiterate them here but follow the link provided for further explanation.  One of the most useful clinical exercises/tests is what I often refer to as tri- bike hip extension.  In this position the patient is in a crouched kneeling position (as a triathlon bike rider) with one leg trailing back behind.  The trailing knee is then bent and the test/exercise is to lift the leg by driving the heel towards the ceiling.  Most importantly – the lower the crouch position the greater the degree of difficulty on lift.

I find this an extremely potent test for evaluating hip extensor function and it also yields good information about trunk stability and compensatory strategies but more on that  another time.

P.S. When patients cramp in the hamstring, doing this exercise, you can bet your bottom dollar they are still trying to use the hamstring as opposed to gluteus maximus to execute this movement.  In that event one needs to revert to a less challenging position.

Enjoy the clinical challenge.

David

© David for PhysioDigest - an educational resource for the musculoskeletal rehabilitation community, 2009. | Permalink | No comment | Add to del.icio.us
Post tags: Biceps femoris, clinical measurementm core stability, gray cook, Hamstring Flexibility deficits, hamstring rehabilitation, Hamstring strain, hamstring treatment, low back pain, movement patterns, multifidus, muscle tone, peter o'sullivan, saggittal plane mechanics, Semimembranosis, Semitendinosus, Shirley Sarhmann, strength testing, transversus abdominis

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