postoperative immobilization in arthroscopic rotator cuff repair; the use of botulinum toxin A

The general accepted postoperative protocol for rotator cuff surgery is a
six-week immobilization period with the arm in resting position in a sling. The
immobilizing sling reduces the chance of failures in tendon healing by motion
and gives the repair time to get strong and stable. However, it disables
patients to fulfill their general daily activities and the necessary activities
during work. Besides immobilization, the patients often experience a high level
of postoperative pain and discomfort.
Injecting botulinum toxin A into the torn muscle causes a reversible paralysis
of the muscle up to 12 weeks after arthroscopic rotator cuff repair, which
should allow the patients to continue their daily activities directly after
surgery, without endangering the rotator cuff repair. Herby, the patient*s
discomfort will be reduced and the importance of the patient*s compliance will
be less. Also, in literature botulinum toxin A is said to have a positive
effect on muscle pain and might decrease the amount of postoperative pain
experienced.
This study defines the possibility of using botulinum toxin as a method for
postoperative immobilization.

Primary objective(s): Is to determine the effect of botulinum toxin injections
on postoperative pain and discomfort after an arthroscopic rotator cuff repair.

Secondary: To determine whether postoperative immobilization of the rotator
cuff, after arthroscopic rotator cuff repair using botulinum toxin, leads to
no more surgical failures than using traditional six-week sling immobilization.
Showing it to be a promising new method for postoperative immobilization, it
could allow patients to continue daily activities without endangering their
repair.

An additional purpose is to determine difference in muscle activity in the
ruptured, immobilized and repaired rotator cuff, using electromyographic
analysis (EMG).

Randomized Controlled Trial

Patients are randomized into two groups: all patients are treated for
supraspinatus/infraspinatus tendon lesion using a standardized arthroscopic
rotator cuff repair; Group one (control group) will receive standard
postoperative immobilization (e.g. a sling for a period of 6 weeks) and group
two (BTA group) consists of patients in which the supra/infraspinatus muscle
are immobilized by botulinum toxine A injections. These patients are
postoperatively allowed to use their shoulder functionally.

Patient burden: The burden for the participants consists of normal outpatient
visits of approximately 10 minutes: preoperative, 1, 3, 6, 12 weeks, * and 1
year.
Assessment of surgical outcome; e.g. tendon integrity of the surgical repair
will be performed during the six standard outpatient visits, using non-invasive
and painless, ultrasound. An additional 5-10 minutes are added to total
visiting time. At 6 months a MRI scan, non invasive/ harmful imaging will be
performed.
In addition, the patients are asked to fill in the Oxford Shoulder
Score a twelve question questionnaire: pre- and 3; 6; 12 months postoperative
as well as the Constant-Murley score. The former also includes a physical
examination of range of motion and strength measurements.
Postoperative pain is assessed using the Visual Analogue Scale (VAS):
daily during the first week, and weekly in the second, 3rd and 6th week as well
the 3rd, 6th, and 12th month.
To investigate the differences in electric muscle activity all patients in the
trial will undergo fine needle EMG. This is an invasive but well established
and validated technique to evaluate muscle contraction and nerve conduction. It
takes up to * hour to perform and patient burden is low.

Risk/ benefit analyses: Possible risks associated with this protocol
consists of side effects caused by the injection of botulinum toxin A (BTA) and
the risk of a re-tear in the tendon due to tension on the repair despite
immobilization of the tendon using BTA. Botulinum Toxin A is not hazardous for
patients because the dose administered for therapeutic use is only a fraction
of the dose required to cause dangerous systemic side effects (e.g. muscular
weakness in muscles which make swallowing possible could lead to difficulties
in swallowing). Other side effects described include: flu like symptoms,
headache, light-headedness, chills, hypertension, diarrhea, abdominal pain.
There is no evidence of organ damage caused by BTA.

Changes to the target muscles: after repeated BTA administration
hypotrophy of the muscle could develop but necrotic changes or fibrotic changes
have not been observed.

Based on the outcome of the pilot study, we conclude that botulinum
toxin A is a promising new method for postoperative immobilization allowing
patients to continue their daily activities without endangering their repair
with minimum risks. This might lead to great burden reduction and freedom in
movement postoperative, in a very big group of future patients in need of a
rotator cuff repair.