POSTER ABSTRACTS - ISAKOS

length. In response to this phenomenon, my
colleagues and I have been performing distal
clavicle resection to safeguard against the failure
of conservative treatment in subtle AC instability.
We have executed a study with the purpose of
evaluating the midterm evolution of subtle AC
instability treated with arthroscopic distal clavicle
resection. Seventeen consecutive patients with
subtle instability of distal clavicle after grade II
injury were identified. The mean follow up was 2
years (1-4 years).Shoulder function was assessed
using the Constant - Murley score, which ranges
from 37 to 69. Pain was assessed using a linear
visual analogue pain scale ranging from 0 to 10.
Postoperative constant score ranged from 51 to 88
(average 70). Review of postoperative radiographs
recorded an average distal clavicle resection of
5.5mm. The overall result for the 17 shoulder were
very satisfy in 3 (18%), satisfy in 10(59%), and
dissatisfy in 4 (23%). therefore satisfactory result
were noted in 75% of this overall treatment group.
In conclusion, Arthroscopic distal clavicle
resection in patient with subtle distal clavicle
instability is a reasonable initial treatment option
with lower morbidity.
E-poster w/ Standard #938
Computer-Assisted Analysis of Gleno-humeral
Joint and Rotator Cuff Passive Kinematics
Stefano Zaffagnini, Bologna, ITALY, Presenter
Sandra Martelli, Bologna, ITALY
Riccardo Minola, Milano, ITALY
Paul Golano, Barcellona, SPAIN
Daria Giovannucci, Bologna, ITALY
Istituti Ortopedici Rizzoli, Bologna, ITALY
1 Introduction
Accurate knowledge of the intrinsic kinematics of
the shoulder and the relation between different
structures inside the joint are fundamental to
achieve an overall comprehension of the
mechanism of failure or inflammation of the
rotator cuff muscle during specific sport activity or
during the early degenerative phase of such
district [1,2].
The study was developed to describe accurately,
utilizing a computer-assisted method, the
anatomic features of a shoulder joint including
centre of rotation, articular joint surface of the
humerus and glenoid, the coracoid process, the
acromion and the coraco-acromial ligament as
well as the supra-spinatus and infra-spinatus
insertion area on the humerus and scapula.
Experimental data were then elaborated in order
to reconstruct the relative position among all
anatomical structures during the recorded
abduction, forward elevation as well as internal
and external rotation. In this way the distances,
elongation and relationship of anatomical
structures with respect to the others were
obtained during the determined range of motion
in a set of normal joints.
2 Material and Methods
We recorded motion and articular surfaces with
the Faro Arm digitizer (FARO Technologies, Lake
Mary, Florida, USA), a 6-degrees-of-freedom
electrogoniometer, that allows a computer
elaboration of anatomical and kinematics data
with submillimetric accuracy, as described in
detail in [3].
We examined three normal shoulders randomly
chosen. All specimens had full range of motion,
no evidence of rotator cuff tears, arthritis or bone
deformity.
The scapula was fixed to the experimental
desktop, while the humerus was left intact up to
the elbow and mobile.
Passive motions were recorded with the intact
joint and repeated without deltoid and teres
minor. The relative position of humerus and
scapula was recorded thrice at different range of
passive motion (ROM): elevation (ELEV), in
abduction(ABD), and in internal and external (IE)
rotation at 0?and 90? of the humerus.
Then the coraco-acromial ligament and the supraspinatus
and infra-spinatus muscles were isolated
and their insertion area on humerus and scapula
was digitized. We also identified four main fibers
on the mentioned muscles, digitizing couples of
corresponding insertion points on humerus and
scapula to have a description of tendon fibers
behaviour during ROM. In order to have a
complete description of the joint, we recorded the
bone surfaces of the gleno-humeral joint, the
scapula, coracoid and acromion surfaces
accurately. Typical anatomical features, such as
centre of glenoid cavity, extremity of acromion
and posterior point of coracoid were elaborated
from these data.
3 Results
The gleno-humeral joint was reconstructed during
the passive motion.
A first group of results concerned the anatomy of
the gleno-humeral joints; the humerus head of
our joints had a diameter of 43.3 ± 0.7 mm, while
the size of the minimal parallelepiped containing