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The Pressure Biofeedback Unit for Testing and Retraining of Lumbo-pelvic Control

28th September 2012

The pressure biofeedback unit -  useful clinical tool to help identify uncontrolled movement of the lumbopelvic region

This review presents how to use the Pressure Biofeedback Unit for testing core control

During limb load tests and exercises the pressure biofeedback can objectively monitor for uncontrolled movement.

This is how to assess for uncontrolled lumbar flexion


Test: for lumbo-pelvic – flexion control
Double Bent leg lift (bilateral) – crook lying
    

    Control: lumbar neutral & control lumbo-pelvic flexion
    Move: below - flex at hips

Benchmark:90° bilateral unsupported hip flexion


    Start positon

Ideal:

In supine / crook lying place the pressure biofeedback in the lumbar lordosis (centred about L3). Inflate the pad to a base pressure of 40 mm Hg. Keeping the knees bent and the lumbar spine neutral (no pressure change), slowly lift both feet off the floor until both hips are flexed to 90°. Hold this position

 

and keeping the lumbar spine controlled (no pressure change) slowly lower both heels to the floor.


•   Uncontrolled flexion of the lumbar spine


In the process of trying to keep thelumbar spine neutral, the pelvis must not tilt posteriorly and flex the lumbar spine. The anterior abdominal wall should stay flat. Dominance of rectus abdominis causes the anterior abdominal wall to ‘bulge’ out, flexing the trunk and increasing the pressure in the unit. A pressure increase of more than 10 mm Hg (increase to more than 50 mm Hg) indicates gross posterior tilt and uncontrolled lumbar flexion.

As soon as any pressure increase (towards 50 mm Hg) is registered the movement must stop and the feet lower back to the start position. If control is poor, a series of graduated progressions using relatively less load and specific facilitation of the oblique abdominals can be used.

Here are some correction strategies:


In supine / crook lying place the pressure biofeedback in the lumbar lordosis (centred about L3). Inflate the pad to a base pressure of 40 mm Hg. The pad maintains the neutral spine.


•    Multifidus facilitation
In supine / crook lying place the pressure biofeedback in the lumbar lordosis (centred about L3). Inflate the pad to a base pressure of 40 mm Hg.  Try to visualise pulling the sacrum up along the bed towards the shoulders. The lumbar lordosis should increase slightly and the pressure should decrease. Do not use thoracic extension to decrease the pressure - this is noted with  lifting of the chest.

Ideally, with efficient multifidus recruitment, the pressure should decrease by 5-10 mm Hg. (from 40 mm Hg to approximately 35-30 mm Hg). The pressure increase should be able to be consistently maintained.


•    Static Diagonal: isometric opposite knee to hand push
With the PBU at 30-35 mm Hg or other hand to monitor that no pressure change, slowly lift one knee towards the opposite hand and push them isometrically against each other on a diagonal line. Push for 10 seconds and repeat 10 times so long as control is maintained (no pressure change).

As soon as any pressure increase or decrease is registered the movement must stop and return to the start position. Do not stabilise with the opposite foot or allow substitution or fatigue.


•    Static Diagonal Heel Lift: isometric knee to hand push + 2nd. heel lift
With the PBU at 30-35 mm Hg or other hand to monitor that no pressure change, slowly lift one knee towards the opposite hand and push them isometrically against each other on a diagonal line. While keeping this pressure slowly lift the second heel off the floor and bring it up beside the first leg. Hold this position for 10 seconds and repeat 10 times so long as control is maintained (no pressure change).

As soon as any pressure increase or decrease is registered the movement must stop and return to the start position. The point of greatest risk of losing stability is when the second heel leaves the floor. Do not allow substitution or fatigue.


•    Alternate Single Leg Heel Touch: (as decribed by Sahrmann level 1)
With the PBU at 30-35 mm Hg or other hand to monitor that no pressure change, slowly lift one foot off the floor and then lift the second foot off the floor and bring it up beside the first leg.  Hold this position and keeping the back stable (no pressure change) slowly lower one heel to the floor and lift it back to the start position. Repeat this movement, slowly alternating legs, for 10 seconds so long as stability is maintained (no pressure change), and then return both feet to the floor. Repeat the whole process 10 times.

As soon as any pressure increase or decrease is registered the movement must stop and return to the start position. The point of greatest risk of losing control is when the heel is lowering to the floor. Avoid substitution or fatigue.

 

This is how to assess for uncontrolled lumbar extension

Test: for lumbo-pelvic – extension control
Double Bent leg Lower (bilateral) – crook lying


     Control: lumbar - hold neutral & control lumbo-pelvic extension

     Move: below – extend at hips from 90° flexion to 45°

Benchmark:double bent leg unsupported lowering to heel contact


Ideal:
During limb load tests and exercises the pressure biofeedback can objectively monitor  uncontrolled movement of the lumbar spine. No pressure change = no uncontrolled movement. A base pressure (40 mm Hg) is used to position and support the spine in neutral alignment. When the stability muscles (local and global) are activated, a consistent  in pressure (from 40 to 50 mm Hg) is observed.

Supine Crook Lying:  
In supine / crook lying place the pressure biofeedback in the lumbar lordosis (centred about L3). Inflate the pad to a base pressure of 40 mm Hg

The therapist then passively lifts both feet off the floor until the hips are flexed to 900. The subject should then actively hold this position. Normally a pressure increase is noted at this point as the back flexes slightly onto the PBU. Keeping the thighs vertical (hips at 90°) the subject is instructed to actively reposition the pelvic tilt to return to a base pressure of 40 mm Hg.

Then the subject is instructed to slowly lower both heels (simultaneously) to the floor while keeping the back stable (no pressure change). Ideally, the subject should be able to slowly lower both feet towards the floor and hold them steady just a few millimetres off the floor while keeping the pressure constant at 40 mm Hg. As soon as any pressure decrease (towards 40 mm Hg) or increase (towards 60 mm Hg) is registered the movement must stop and the feet returned (one at a time) back to the start position.


•    Uncontrolled Lumbar extension:
In the process of trying to keep the back neutral as the legs lower the feet down to the floor, the lumbar spine must stay neutral with a constant flattening pressure and move into extension or anterior pelvic tilt. A loss of flattening pressure (decrease to less than 40 mm Hg) indicates gross anterior tilt and a loss of control into spinal extension. Poor control of extension can be attributed to inefficient oblique abdominals and anterior fasciculus of psoas major.

Correction:


With  uncontrolled movement, a series of graduated progressions using relatively less load and specific facilitation of the oblique abdominals can be used.


•    Oblique Abdominal facilitation
In supine / crook lying place the pressure biofeedback in the lumbar lordosis (centred about L3). Inflate the pad to a base pressure of 40 mm Hg.  Don’t breathe as the low lateral abdominal wall is hollowed (drawn up and in) in an attempt to flatten the lumbar lordosis and increase pressure on the pad. Specific external oblique abdominal facilitation is achieved by cueing active lower ribcage depression. Specific internal oblique abdominal facilitation is achieved by lifting the ASIS.  Ensure that no pelvic tilt occurs. The pad maintains the neutral spine. Hold this contraction and breathe gently.

 

Oblique abdominal faciliation

Ideally, with efficient oblique abdominal recruitment, the pressure should increase by 8-10 mm Hg. (from 40 mm Hg to approximately 48-50 mm Hg). The pressure increase should be able to be consistently maintained.

A pressure increase of 15-20 mm Hg (55-60 mm Hg) indicates posterior tilt and reversal of the lumbar lordosis to the flat position. This pressure change is associated with bracing strategies. A bracing strategy is acceptable under double leg load when strength training is the aim, rather than motor control training.

Keeping the knees bent and the lumbar spine neutral (no pressure change), lift both feet off the floor (one at a time) until the hips are flexed to 90°. The subject should then actively hold this position keeping the back stable (no pressure change). Then the subject is instructed to slowly lower one foot at a time both heels to the floor. As soon as any pressure decrease (towards 40 mm Hg) or increase (towards 60 mm Hg) is registered the movement must stop and the feet lower back to the start position.

•    Static Diagonal: isometric opposite knee to hand push
Activate oblique lower abdominals  with a neutral spine (PBU at 48-50 mm Hg or other hand to monitor that no pressure change = spinal stability). Slowly lift one knee towards the opposite hand and push them isometrically against each other on a diagonal line. Push for 10 seconds and repeat 10 times so long as stability is maintained (no pressure change).


As soon as any pressure increase or decrease is registered the movement must stop and return to the start position. Do not stabilise with the opposite foot or allow substitution or fatigue.

•    Static Diagonal Heel Lift: isometric knee to hand push + 2nd. heel lift
Activate lower oblique abdominal hollowing with a neutral spine (PBU at 48-50 mm Hg or other hand to monitor that no pressure change = spinal stability). Slowly lift one knee towards the opposite hand and push them isometrically against each other on a diagonal line. While keeping this pressure slowly lift and lower the second heel. Hold this position for 10 seconds and repeat 10 times so long as control is maintained (no pressure change).

As soon as any pressure increase or decrease is registered the movement must stop and return to the start position. The point of greatest risk of losing stability is when the second heel leaves the floor. Do not allow substitution or fatigue.

•    Alternate Single Leg Heel Touch: (Sahrmann level 1)
Activate lower oblique abdominals with a neutral spine (PBU at 48-50 mm Hg or other hand to monitor that

no pressure change = spinal stability). Slowly lift one foot off the floor and then lift the second foot off the floor and bring it up beside the first leg. (Sahrmann levels 1-5 all use supine crook lying with hips flexed to 90° and both feet off the floor as the starting position).

Hold this position and keeping the back stable (no pressure change) slowly lower one heel to the floor and lift it back to the start position. Repeat this movement, slowly alternating legs, for 10 seconds so long as stability is maintained (no pressure change), and then return both feet to the floor. Repeat the whole process 10 times.

As soon as any pressure increase or decrease is registered the movement must stop and return to the start position. The point of greatest risk of losing stability is when the heel is lowering to the floor. Do not allow substitution or fatigue.

Useful references

Comerford & Mottram 2012 Kinetic Control The Management of Uncontrolled Movement. Elsevier

 

Jull G, Richardson C, Toppenberg R, Comerford M, Bui B 1993 Towards a measurement of active muscle control  for lumbar stabilisation  Australian Journal of Physiotherapy 39, 187-193

 

Richardson  C, Jull G, Toppenberg R, Comerford M  1992 Techniques for active lumbar stabilisation for spinal protection: a pilot study. Australian Journal of Physiotherapy 38, 105-112

 

Roussel N A, Nijs J, Mottram S, van Moorsel A, Truijen S, Stassijns G. 2009 Altered lumbopelvic movement control but not generalised joint hypermobility is associated with increased injury in dancers. A prospective study. Manual Therapy 14(6): 630-635

 

Keywords: Clinical Tips