A 55 year old female patient underwent knee surgery reporting a severe quadriceps muscle (QM) group atrophy showing no improvements after 11 months of rehabilitative physiotherapy.
Patients with Knee disorders exhibit a decreased activation of quadriceps compared to the uninvolved limb suggesting that neural mechanisms contribute to the weakness of the quadriceps.
Weakness of the quadriceps muscle results in important functional consequences such as decreased gait speed,
balance,
difficulty with stair climbing,
and rising from a chair and risk of falls.
After the cessation of inconclusive therapy,
a 50 minute rMMS treatment was applied to the diseased QM,
3 days a week for 7 weeks.
For the rMMS a Medtronic MagPro R100 device (Medtronic Denmark A/S,
Copenhagen,
Denmark) connected to elliptical RT-120 and circular MCF-125 coils was used.
The performed stimulation protocol was: activation for 5 seconds from 20 to 30 pps with rise time of 0.8 sec and fall time of 0.8 sec,
rest of 10 seconds.
We directly stimulated the vastus lateralis muscle and rectus femoris muscle (RFM) of the QM group.
Stimulation was preferably applied midway between the upper third and the remaining two thirds of the body of the muscle,
at the point of maximum response.
In rMMS a current flow through a solenoid and causes a rapid change of the magnetic field,
which in turn induces a depolarization of excitable tissues (muscle) such as that which is determined for the electrical stimulation .
The advantage is that the current does not pass through high resistance tissues such as the skin for which the nociceptors are not activated and so it is possible to obtain a valid muscle contraction without inducing stimulation pain.
The RFM was the muscle evaluated with Ultrasound due to the fact it was the one mainly stimulated by the rMMS treatment.
B-Mode US examination and Elastosonography were performed in order to add imaging and functional evaluations to the rMMS treatment.
B-Mode US muscle structure evaluation and thickness measurement and Elastosonography color coded tissue stiffness map (MyLabAlpha,
Esaote S.p.A.,
Florence,
Italy) were evaluated before (T0) and after (T1) the rMMS treatment.
VAS,
MVC and SF-36 scores were also evaluated at T0 and T1.
Elastosonography is a non-invasive method to support the physician in assessing tissue elasticity.
This technology provides additional information to standard B-Mode,
a better definition of the lesion area,
and it is suitable for diagnosis and follow-up.
Moreover,
it gives information on the tissue elasticity by associating different chromatic patterns.
Real-time elastosonography (ElaXto; Esaote S.p.A.,
Florence,
Italy) is based on the concept of elastic strain: an object,
subject to stress,
distorts proportionally to the intensity of the applied stress and depending on the material.
It is known that tissue elasticity,
in different districts,
is correlated to pathologies.
Palpation,
which is routinely used in clinical exams,
is based on this assumption.
In order to perform the elastosonographic exam,
the user has to apply a perpendicular pressure through rhythmic movements on the tissue under exam.
Thanks to the pressure given by thataction,
it is possible to evaluate the modification of the echo signal and thus to compute how the different tissues distort (if they are soft) or move (if they are hard) compared to the probe position.
The result of this calculation,
computed in real-time,
is shown by a color image overlapped to the B-Mode image.
The deformability degree is given by a chromatic scale.
ElaXto is a qualitative analysis where the estimation of strain information is computed in relation to the surrounding tissue.
The computed strain information is dependent on the tissue of the Region of Interest (ROI).
To date,
elastosonography was not applied on in vivo leg muscle for tissue elasticity investigations in relation to magnetic stimulation treatment assessment and follow up.
Elastosonography is a relatively-quantified technology: tissues are shown harder or softer in a relative not in an absolute manner,
therefore,
tissues soft are softer than the average value of the tissues within the ROI while they can be hard if compared to other tissues.