Civil Engineering Reference
In-Depth Information
TABLE 27.1 Geometric Parameters of the Glenoid Fossa Shapes at the Seven Nodes (i
¼
7) for 12 Subjects
Subjects
1
2
3
4
5
6
7
8
9
10
11
12
z
1
mm
67.2
14.2
30.8
28.6
27.8
34.3
10.6
37.9
49.4
8.2
67.1
20.8
z
2
mm
56.4
11.8
24.1
30.1
33.1
23.7
16
23.7
38.3
26.5
37.3
13.4
z
3
mm
38.2
8
18.9
14.4
30.5
14.2
7.7
10.1
30.4
15.1
17.6
12.3
z
4
mm
30.3
1.1
8.9
9.4
16.5
4.7
4.6
8.3
22.4
34
11.5
10.1
z
5
mm
16.3
1.2
2.6
5.6
8.8
1.2
0.7
1.7
15.1
0.9
5.3
8.8
2
2
2
z
6
mm
8.4
2.2
2
3.4
2
4
0.7
2
5.6
2
2.8
2
5.8
5.4
2
1.9
2
7.2
3
z
7
mm
5.7
6
2
8
2
3.7
1.7
2
14.6
2
5.5
2
12.5
2
11.4
2.8
2
20
2
6.5
f
1
8
50.2
78.5
70
72.8
69.1
63.3
75
66
58
93.3
53
57
f
2
8
56.4
81.7
76
71.5
64.7
73
64
78
66
74
73
72
f
3
8
70.7
87.3
81
87.1
67
83.5
84
95
73
87.5
92
74
f
4
8
78.7
98.5
93
92.9
82.4
95.7
93
97
81
103.6
98
81
f
5
8
95.4
102.7
101
97.8
92.2
103.9
109
106
90
107.5
105
85
f
6
8
105.8
95.9
109
110.9
104.4
110.5
116
116
103
112.1
120
109
f
7
8
109.6
87.3
116
110.4
102.5
123.6
125
124
124
102.4
132
136
Note: z
i
is the distance between the middle deltoid attachment and a point at which a tangent to the glenoid foosa crosses
the Z-axis and f
i
is the tangent inclination.
Z-axis from the lateral margin of the acromion, the lateral deltoid muscle attachment, were respectively
from z
1
33.1
+
18.9 mm to z
7
5.5
+
8.0 mm with a maximum of 67.2 mm and a minimum of
¼
¼ 2
20.0 mm. The results of the measurements are summarized in Table 27.1.
2
27.5 Conclusions
1. The study responds to the recent studies
12
confirming an emerging need to include glenoid incli-
nation, mechanics of the deltoid muscle, and glenoid labrum concavity into stability analyses of
the glenohumeral joint
2. The study implies the practicability of a geometric description of the glenoid fossa which should
no longer be considered as a straight line but as a series of tangents
3. The current study proposed considering the whole planar shape of the glenoid fossa as a mean-
ingful geometric component of the glenohumeral joint
4. Migration of the humeral head along the glenoid fossa is related to the glenoid fossa inclination
and the distance from the glenoid fossa of the deltoid muscle attachment
5. The results for the tangents with supplementary angular values (i.e., in Figure 27.6a f
¼
30
8
and
) demonstrate symmetry because the translations of
the glenoid head along the Y-axis oscillate around the same balance position
6. A tangent to the glenoid fossa, formed by a larger than 90
150
8
; f
¼
50
8
and 130
8
; f
¼
70
8
and 110
8
8
angle to the z-axis improves the
glenohumeral stability significantly
7. The MRI results for 12 subjects confirm variability in tangent inclinations and distances of
tangents from the lateral deltoid attachment
8. Considering and measuring the angles of tangents as the parameters of the glenoid fossa will
provide new information on the interface shape sensitivity of glenohumeral joint stability
9. This method may help in early diagnosis of mechanical instability, which can be considered as a
condition predisposing the glenohumeral joint to degenerative change especially for a subject
returning to work after work absence resulting from a work-related injury
10. These analytical mechanical considerations may provide a better biomechanical basis for joint
modeling and lead to consideration of articular geometry during designing of workplaces
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