Biofeedback Training of
the External Rotators to Centralize the Humeral Head in
Patients with Anterior Shoulder Instability and/or Pain.
Linda Saboe, B.P.T.,
Judy Chepeha, Bsc.P.T., M.C.P.A.
David Reid, M.D., M.Ch.H., F.R.C.S.
Gary Okamura, M.D.
Michael Grace, Ph.D, P. Eng
The Glen Sather Sports Medicine Clinic, and the
Division of Orthopaedics.
The University of Alberta
Anterior shoulder instability and impingement are
common athletic complaints associated with overuse, joint
laxity, post-traumatic dislocation and muscle imbalance.
While traditionally treated as clinically discrete
entities, it is now accepted that considerable overlap
exists between functional instability and anterior
Until recently, rehabilitation programs have
emphasized subscapularis strengthening on the assumption
that this muscle provided an anterior buttress,
preventing anterior humeral head subluxation(4-6). Turkel
(1981) has demonstrated inability of the subscapularis to
cover the anterior humeral head in abduction and external
rotation(7) and Garth reports that internal rotation
forces actually contribute to anterior displacement(2).
These findings provide an explanation for high failure
rates of traditional rehabilitation programs(8-11).
Jobe and Perry's electromyograhic work identifies the
external rotators, and in particular, the infraspinatus,
to be the primary dynamic anterior shoulder stabilizers
in abduction and overhead motions(12-14). This dynamic
stability is provided by preventing forward motion of the
humeral head in the glenoid fossa.
In 1988, a treatment protocol utilizing single channel
electromyographic biofeedback was developed; it has been
continuously tested and enhanced through controlled
clinical trials at the University of Alberta. This
program utilizes targeted muscle feedback to perfect
motor skills. By electronically monitoring and amplifying
activity of the external rotators during an apprehensive
motion with immediate visual and auditory feedback to the
subject, the performance is changed or shaped. This
program, which emphasizes muscle control rather than
strength, requires motivation, training, and lifelong
routines to maintain the established engram and control
SINGLE CHANNEL EMG BIOFEEDBACK SYSTEM
The MyoTrac single channel EMG biofeedback unit, from
Thought Technology, is valuable in the reinforcement of
appropriate external rotator activity. Patients are
provided with visual and auditory feedback of appropriate
muscle activity. The unique MyoScan sensor amplifies the
muscle signals at the pickup site, thereby providing
excellent sensitivity with no electrical interference
(see figures 1 and 2)
CHANNEL BIOFEEDBACK TREATMENT PROGRAM
- Electrode placement is critical. Using the
disposable triode electrodes, attach the sensor
below the scapular spine with the 2 active
electrodes parallel to the orientation of the
muscle fibers. Do not place it over the
posterior deltoid as increased activity in this
muscle would drive the humeral head anteriorly.
The patient remains connected to the biofeedback
unit during training and must practice at home,
both with and without the unit. For home
practice, the therapist might wish to place an
indelible mark on the skin for electrode
Figure 1. Inside Pannel settings
Figure 2. Threshold and Gain settings
- To determine threshold and gain settings, have
the patient flex the shoulder forward to 70
degrees with the gain switch at X1, and turn the
threshold control until the yellow LED
illuminates. If the activity is greater than 10uV
at 70 degrees, set the gain settings to X10.
Again, have the patient flex the shoulder forward
to 70 degrees while turning the threshold control
until the yellow LED illuminates.
- Ensure the shoulder is in a pain-free neutral
position, the threshold switch is set to 'CONT',
the volume is set at a pleasant level (with or
without the earphones) and the threshold control
and gain reading switch remain in the positions
set previously in step 2. Instruct the patient to
use the visual and audio feedback to increase EMG
activity well above the yellow LED. This is done
by tightening the rotator cuff muscles in
the neutral position in order to glide and
hold the humeral head posteriorly (figure 3).
This is a key component and must be successfully
performed 100 times (ten sets of 10) prior to
progressing to active movement. The use of many
repetitions builds endurance. This procedure is
quite fatiguing; it may require several sessions
before the patient can progress to step 4.
Figure 3. Teach contraction in neutral position
- With the theshold set at twice the value achieved
in Step 2, place the patient's elbow in flexion
(figure 4). Instruct to forward flex the adducted
and neutral rotated shoulder to 90-100 degrees.
As the shoulder is flexed between 70 and 90
degrees, have the patient tighten the rotator
cuff and achieve the threshold setting, trying to
light-up the lights to the right of the first
yellow one. If pain or a sense of subluxation is
experienced, stop, rest and start again through a
smaller arc of movement and/or with reduced
threshold settings. When the patient can
successfully perform 100 consecutive repetitions,
progress by increasing the threshold and/or
movement as shown in figure 5.
Figure 4. Forward flex to 90-100 degrees
As the patient masters each level, progress through
the following exercises:
a) Forward flexion with a straight elbow.
b) Forward flexion with increasing external rotation.
c) Abduction with flexion progressing to elbow
d) Abduction with elbow extension with increasing
e) Abduction from flexion.
f) Abduction from flexion with increasing external
g) Reach for objects behind back or overhead.
When the above progression of increasingly difficult
tasks has been completed, progress to the activities
specific to the sport or work task that caused the
difficulty. Break the movement down into component parts
and introduce catching or throwing activities in
preparation for a gradual return to normal activity
(figures 6, 7).
If general weakness exists, instruct the patient in
appropriate progressive resistance exercises. Include
pushups for serratus anterior (with the arms abducted)
and external rotation exercises resisted using surgical
tubing. Avoid resisted exercises which load in
an impingement position (figure 5). All pain free
activities are allowed and encouraged. The patient will
require two to three weeks of supervised physiotherapy,
but must do a life-long home program to maintain the engram. It might be desirable for patients to return for
occasional brief refresher courses.
Figure 8. Instability and impingement are related
This program emphasizes muscle control. Strength
acquisition is important, but secondary. Electrode
placement is critical. The biofeedback program is
physically and mentally demanding, therefore, appropriate
rest periods and encouragement must be provided. Slow and
careful progression is usually necessary. Commitment by
the therapist and client are required for the program's
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Biofeedback Foundation of Europe