1. Evaluation of the antero-superior laxity of shoulder
The R-45 Test
Evaluation of the antero-superior laxity of shoulder
O Gagey, MD, PhD*; Kazuhisa Matsui, PT**; Takashi Tachibana, PT**; Katasuya Nobuhara MD**
* Team 1 : Paris-South University, France
** Team 2 : The Nobuhara Hospital, Japan

2. INTRODUCTION
Except the concept of fibrous lock, the anterosuperior stabilisation of the glenohumeral joint (GHL) has been poorly studied.
An anatomical study has been undertaken to contribute to the understanding of the physiology of the antero superior stabilisation of shoulder.

3. Material and methods
Anatomical study (team 1) : fresh normal shoulders were studied to look at the limitation of External Rotation at 45° of elevation in the plane of the scapula (ER-45). Arthroscopic sequential section of MGH and of the upper tendon of the subscapularis were performed.
Clinical test (team 1) : healthy subjects without evidence of constitutional hyperlaxity were tested : the arm was passively hold with 45° elevation in the plane of the scapula with the elbow at 90°, passive external rotation of the arm was measured by two different observers with a Plurimeter ® (see the technique below)

4. The arm is hold at 45° elevation + abduction, the forearm is vertical and then gently externally rotated

5. The arm is hold at 45° elevation + abduction, the forearm is vertical and then gently externally rotated

6. Material and methods
Validation of the clinical test in normal conditions (team 2) : based only on a written and illustrated description of the test healthy subject were studied by the team #2.
Validation of the clinical test in pathologic conditions (both teams) : Patients suffering of 1) anteroinferior instability, 2) anterosuperior instability, 3) multidirectionnal instablity, 4) rotator interval syndrome and 5) traumatic rupture of the upper part of the subscapularis were prospectively tested by both teams.

7. Results 1 Anatomical study :
In 58 specimens. External rotation in ER-45 was restricted by both MGHL and upper tendon of the subscapularis. ER-45° was always inferior to 15 +/- 6 °.
Section of the middle glenohumeral ligament increased the range of ER -45 up to 10°(7 – 15), Section of the upper part of the subscapularis increased the range of ER-45 up to 10° °(5– 15).
Section of both structures increased the range of ER - 45 up to 20 ° (15 – 30).

8. Results 2
Clinical test in normal conditions : Measure done by T1 on 92 healthy Caucasians demonstrated that ER-45° was never superior to 15 °(mean 11°, +/-7°).
Validation of the “normal” test : Measures done by T2 evidenced in 107 Asian volunteers a mean value of 9 +/-12° and never more than 15° but in 8 cases where R-45 was more than 15° bilaterally.

9. Results 3 Clinical test in pathologic conditions (by both teams) :
Post traumatic antero inferior instability : 175 Pts were tested : 100% had a normal R-45 test
Antero superior instability : 8 cases were tested : the test was always normal.
Multidirectional instability : 25 cases were tested : the test was always positive.
In 85 posttraumatic cases without fractures, the test was found positive 6 times unilaterally, in these 6 cases ONLY MRI evidenced a tear of the upper part of the subscapularis.

10. Results 4
In 30 rotator interval lesions - as defined by Nobuhara - the test was positive 10 times, positive bilaterally 7 times and normal 13 times.

11. Discussion
The R-45 test is the first direct assessment of the upper and anterior part of the scapulohumeral joint. It provides useful information regarding MGHL laxity AND upper part of the subscapularis.
We evidence a quite constant value for the ER – 45 test in normal volunteers

12. Conclusion
A R-45 test inferior to 15° indicates a normal condition of both MGHL and upper part of the subscapularis.
A posttraumatic unilateral positive R-45 test strongly indicates a tear of the upper part of the subscapularis.
In case of “unclear” shoulder instability a positive test strongly suggests the possibility of an anterosuperior instability.