The influence of active abduction on the subacromial space in patients with rotator cuff tears;vs. healthy controls

Rotator cuff tears are a frequently diagnosed cause of shoulder complaints, and
over the past years, there has been an increase in surgical treatment of
rotator cuff tears. However, literature on the subjects of indication and
timing of surgical treatment for rotator cuff tears remains scant, and reported
results are variable. Furthermore, Magnetic Resonance Imaging (MRI) studies
demonstrated that the prevalence of asymptomatic rotator cuff tears ranges up
to 54% in subjects over 60 years old, making it difficult to differentiate
between symptomatic and asymptomatic cuff tears, consequently complicating
diagnostic and therapeutic decision making.

Superior translation of the humeral head on a standard shoulder radiograph is
indicative for rotator cuff (RC) tears. It has been reported that active
abduction increases superior translation as a consequence of superiorly
directed forces of the deltoids. In patients with RC pathologies, there is an
excessive superior translation during abduction, due to diminished function of
the RC muscles as the primary stabilizers of the glenohumeral joint.
Additionally, electromyography (EMG) studies have shown arm adductor muscle
co-activity during active arm abduction tasks in RC patients. Hypothetically,
these adductors are activated to counteract the superiorly directed forces of
the deltoid muscles.
However, current methods to determine this active superior translation are
elaborate and are not applicable to assess cuff insufficiencies in clinical
setting. In this project we propose to modify standard, passive, shoulder
radiographs with two additional active isometric tasks (abduction and
adduction) in order to develop a sensitive method to individually quantify
active superior translations as a potential measure for rotator cuff
dysfunction.

Patients with RC tears are the demonstrator group for general cuff diseases
related with superior translation and RC insufficiency, i.e. impingement.
Therefore, we will analyze this dynamic superior translation in RC patients.
Our hypothesis is that a radiograph acquired during an isometric abduction task
will show a detectable superior humeral head translation compared to standard
AP shoulder radiographs in patients with RC tears.

ADDENDUM:
Now the introduced method has proven it is reliable and easily applicable in 20
rotator cuff tear patients and 30 impingement patients (protocol SISTIM, ABR
28090.058.09), healthy control measurements need to be obtained for further
interpretation of the results in patients.

To assess the difference in acromiohumeral (AH) distance reduction during
active isometric abduction tasks (with respect to rest radiographs) between the
asymptomatic and symptomatic shoulder in patients with a unilaterally diagnosed
RC tear.



ADDENDUM:
Assessing subacromial space (AH) in rest, and the degree of cranialisation
during abduction and adduction tasks in combination with muscle activation
patterns in healthy subjects vs. rotator cuff tear patients (this protocol, ABR
NL34745.058.10) and subacromial impingement patients (protocol SISTIM, ABR
28090.058.09).

Experimental validation study

Participating patients will receive standard care. The investigations for this
study will take around one hour: filling out the questionnaires for 15-20
minutes, experiment for 40-45 minutes. There is no potential benefit for the
individual patient. Per subject six (n=6) additional radiographs of the
shoulders are acquired: 3 of the symptomatic shoulder, and 3 of the
asymptomatic shoulder.


ADDENDUM
Healthy subjects: input of time will be less than 1 hour. 3 Shoulder
radiographs will be acquired instead of 6. No questionnaires.