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Journal of the Anatomical Society of India

Study of Osteometric Measurements of Articular Facets From C3 to S1 (part 3)

Author(s): Patel M M, Singel T C, Gohil D V, Pandya A M.

Vol. 56, No. 1 (2007-01 - 2007-06)

TABLE-7: Range, Means and S.D.s of the Right Inferior articular facets

VERT
EBRA
W H W/H A
Range Mean S.D. Range Mean S.D. Range Mean S.D. Range Mean S.D.
C3 7-15 9.90 1.52 7-10 8.62 1.12 0.80-1.88 1.16 0.22 138.465-94.2 67.21 3.98
C4 8-15 10.50 1.45 7-13 8.96 1.40 1.00-1.67 1.19 0.17 37.68-132.665 74.72 19.50
C5 8-15 10.77 1.63 7-11 8.43 1.30 1.00-1.86 1.30 0.23 42.39-105.975 71.83 17.84
C6 7-15 10.93 1.77 7-10 7.97 0.87 1.00-1.86 1.38 0.21 38.465-105.975 68.86 16.19
C7 8-14 10.83 1.46 6-13 8.73 1.51 1.00-1.71 1.27 0.23 42.39-132.665 74.78 19.21
T1 7-12 9.71 1.16 7-12 9.00 1.24 0.90-1.43 1.09 0.15 32.97-113.04 69.13 15.30
T2 7-12 9.22 1.10 7-12 9.09 1.00 0.8-1.5 1.02 0.10 38.465-113.04 66.38 14.23
T3 7-12 8.96 1.19 6-11 8.67 1.07 0.88-1.5 1.04 0.11 38.465-94.985 61.67 14.43
T4 6-11 8.73 1.26 6-11 8.77 1.22 0.88-1.13 1.00 0.05 28.26-94.985 61.20 16.75
T5 6-11 8.16 1.25 6-11 8.31 1.18 0.78-1.10 0.98 0.06 28.26-86.35 54.24 15.76
T6 6-11 8.21 1.08 7-10 8.21 0.93 0.86-1.22 1.00 0.05 32.97-78.5 53.64 12.90
T7 6-11 8.24 1.16 6-10 8.26 1.16 0.80-1.22 1.00 0.07 28.26-78.5 54.30 14.46
T8 6-11 8.33 1.16 6-10 8.18 1.10 1.00-1.14 1.02 0.05 28.26-86.35 54.45 14.76
T9 7-13 9.36 1.22 7-11 9.00 1.06 0.90-1.44 1.04 0.11 38.465-33 66.80 14.65
T10 7-13 9.63 1.33 8-13 9.50 1.31 0.88-1.25 1.02 0.07 43.96-132.665 73.03 20.73
T11 7-13 9.40 1.52 7-13 9.50 1.41 0.78-1.25 0.99 0.09 38.465-132.665 71.46 21.64
T12 7-11 9.50 1.17 7-13 9.97 1.35 0.82-1.10 0.96 0.07 38.465-112.255 75.33 18.05
L1 8-13 10.60 1.33 8-15 11.27 1.62 0.67-1.00 0.95 0.08 50.24-153.075 94.99 23.72
L2 9-14 11.63 1.36 9-19 12.47 2.02 0.68-1.09 0.94 0.09 63.585-193.895 115.32 30.03
L3 10-15 12.33 1.15 11-17 12.77 1.43 0.77-1.08 0.97 0.07 94.985-186.83 124.53 24.33
L4 10-16 12.97 1.70 11-16 12.83 1.61 0.86-1.27 1.01 0.10 86.35-200.96 132.07 31.56
L5 11-15 13.61 1.26 10-16 13.13 1.61 0.92-1.40 1.05 0.12 94.985-188.4 141.20 27.02


TABLE-8: Range, Means and S.D.s of the Left Inferior articular facets

VERT
EBRA
W H W/H A
Range Mean S.D. Range Mean S.D. Range Mean S.D. Range Mean S.D.
C3 7-15 10.10 1.45 7-11 8.90 1.08 0.90-1.88 1.15 0.20 38.465-94.985 70.81 13.63
C4 9-15 10.54 1.26 7-12 9.14 1.08 0.90-1.67 1.17 0.20 54.95-113.04 75.67 13.25
C5 8-15 11.07 1.68 7-12 8.87 1.33 1.00-1.57 1.26 0.18 49.455-138.16 77.92 20.89
C6 8-15 11.38 2.09 7-11 8.17 1.00 1.00-2.25 1.40 0.26 49.455-113.04 73.44 18.14
C7 9-14 10.90 1.27 6-13 9.23 1.50 1.00-1.86 1.21 0.23 42.39-132.665 79.34 17.72
T1 7-12 9.88 1.21 7-12 9.31 1.18 0.80-1.43 1.07 0.15 38.465-113.04 72.71 15.47
T2 7-12 9.28 1.05 7-12 9.09 1.03 0.8-1.375 1.02 0.10 38.465-113.04 66.82 14.20
T3 7-12 8.85 1.10 6-11 8.63 1.11 0.89-1.22 1.03 0.07 32.97-94.985 60.76 14.59
T4 6-11 8.57 1.30 6-11 8.67 1.32 0.88-1.00 0.99 0.03 28.26-94.985 59.56 17.51
T5 6-11 8.13 1.29 6-11 8.28 1.22 0.78-1.10 0.98 0.06 28.26-86.35 53.92 16.18
T6 6-11 8.18 1.07 7-11 8.33 1.08 0.82-1.22 0.98 0.07 32.97-78.5 54.26 13.57
T7 6-11 8.18 1.14 6-11 8.24 1.21 0.80-1.22 1.00 0.07 28.26-78.5 53.75 14.58
T8 6-11 8.36 1.11 6-10 8.39 1.12 0.88-1.14 1.00 0.05 28.26-86.35 55.97 14.42
T9 7-13 9.48 1.48 7-11 9.00 1.25 0.90-1.57 1.06 0.12 38.465-33 68.08 18.76
T10 7-13 9.67 1.40 8-13 9.60 1.30 0.88-1.11 1.01 0.04 43.96-132.665 74.18 21.39
T11 7-13 9.43 1.55 7-13 9.63 1.43 0.78-1.11 0.98 0.07 38.465-132.665 72.85 22.47
T12 6-11 9.47 1.36 7-14 9.93 1.46 0.67-1.10 0.96 0.09 32.97-120.89 74.92 19.17
L1 8-13 10.77 1.50 8-15 11.37 1.65 0.67-1.10 0.95 0.08 50.24-153.86 97.52 25.95
L2 9-14 11.81 1.49 9-16 12.53 1.74 0.75-1.09 0.95 0.08 63.585-164.85 117.70 28.49
L3 10-15 12.43 1.19 11-16 12.90 1.40 0.77-1.08 0.97 0.07 94.985-176.625 126.86 24.58
L4 11-16 12.83 1.54 11-16 12.90 1.59 0.81-1.25 1.00 0.08 94.985-188.4 131.28 29.92
L5 11-15 13.58 1.52 10-15 13.23 1.52 0.92-1.27 1.03 0.08 86.35-176.625 142.41 29.85


Table 9: ‘t’ values for teh superior and inferior articular facets of vertebrae

VERT
EBRA
Superior articular facets Inferior articular facets
t value for W t value for H t value for W/H t value for A t value for W t value for H t value for W/H t value for A
C3 0.67 0.90 1.65 0.16 0.30 0.54 0.16 0.56
C4 0.01 0.36 0.24 0.07 0.06 0.30 0.21 0.12
C5 0.04 0.09 0.10 0.19 0.40 0.72 0.39 0.69
C6 0.44 0.46 0.05 0.52 0.50 0.47 0.23 0.57
C7 0.54 0.49 0.86 0.15 0.11 0.73 0.57 0.54
T1 0.12 0.55 0.39 0.42 0.31 0.58 0.32 0.52
T2 0.06 0.52 0.25 0.52 0.13 0.00 0.18 0.07
T3 0.32 1.54 1.20 0.38 0.20 0.07 0.20 0.13
T4 0.56 0.56 0.29 3.08 0.28 0.17 0.41 0.21
T5 1.27 0.52 1.74 0.47 0.06 0.06 0.00 0.05
T6 0.66 0.26 0.90 0.27 0.06 0.28 0.11 0.59
T7 0.34 0.62 0.21 0.51 0.12 0.06 0.09 0.09
T8 0.05 0.79 0.64 0.48 0.06 0.44 0.96 0.24
T9 0.70 0.91 1.77 0.02 0.20 0.00 0.26 0.17
T10 0.18 0.56 0.57 0.13 0.05 0.17 0.37 0.12
T11 0.29 0.30 0.58 0.22 0.05 0.21 0.33 0.14
T12 0.19 0.70 0.65 0.37 0.06 0.05 0.01 0.05
L1 0.70 0.68 0.27 0.59 0.26 0.13 0.15 0.22
L2 0.27 0.63 0.57 0.31 0.30 0.07 0.17 0.18
L3 0.08 0.09 0.15 0.13 0.19 0.21 0.09 0.21
L4 0.11 0.08 0.17 0.01 0.18 0.09 0.40 0.05
L5 0.12 0.37 0.37 0.04 0.05 0.14 0.36 0.09

The present study had compared their readings in tabulated form with Panjabi et al (1993) and not with Pal and Routal (1986,1987) because the method employed by Pal and Routal for measurement of Area (A) of articular facets was by graph paper method and then calculating in cmsquare with no mention of measurement of width(w), height(h), width/height ratio; whereas the method used by Panjabi et al and present study was same as to measure the width(W), height(H), Width/Height ratio (W/H) and using the formula to calculate the area, A = 3.14 (W X H)/4. Moreover Pal and Routal(1986,1987) had taken various indices as lamina index, pedicle index, arch index and they had focused their study on weight transmission. The present study was a simple, transparent study providing various parameters of articular facets just as the study by Panjabi et al (1993).Also Pal and Routal (1986,1987), had taken into account only mean of area of inferior articular facets of right and left sides of selected vertebral levels. Tables – 5, 6, 7, 8 shows the range, mean and S.D. of width, height, W/H ratio and area of left and right articular facets for the present study. Table-9 shows the ‘t’value for the significance of difference of means of right and left articular facets (superior and inferior) and the difference was not statistically significant.

Discussion:

According to Pal and Routal (1986,1987), there is shifting of load during weight transmission from anterior to posterior column in lumbar region and therefore in view of the above explanation the width (W) of superior articular facets of lumbar vertebrae will always be more than the height (H) for the transmission of weight.

The present study had observed that in the lumbar region, the superior articular facets showed that the width was more than the height from L1 to S1. But the same pattern was not observed in the study by Panjabi et al; as it showed that the width was less than height in lumbar region (L1 to S1) as shown in tables-1 and 2.

The present study had observed the same pattern of width and height of inferior articular facets as was observed in their counterparts (superior articular facets) as shown in tables- 3and4. The only interesting observation was that the width of inferior articular facets in the lumbar region was always less than the height in the study by Panjabi et al.

There was a huge difference between areas (A) of articular facets on left and right sides at all levels in the studies by Panjabi et al; whereas the bilateral difference between the area (A) on left and right sides of articular facets by the present study was minimal. The above discrepancy could be because of the different approach to the measurement of articular facets by both the studies. Panjabi et al had measured the articular facets from radiographs whereas the present study had measured them manually (920 vertebrae) with the help of vernier caliper.

Earlier Dennis (1983) and Louis (1985), were of opinion that throughout vertebral column, zygapophyseal joints play an important role in weight bearing.

Thus articular facets play an important role in the transmission of weight through spinal column. Pal and Routal (1986), have stated that line of gravity passes posterior to the bodies in cervical region and in thoracic region the compressive force will tend to centre on the vertebral bodies; and since Dhall (1984), had stated that the size of articular facets was correlated with the magnitude of stress imposed on them, the articular processes in the cervical region are very strong bar-like structures and their articulations form strong columns posterolateral to the vertebral bodies (Pal and Routal, 1986).

Thus because of increased magnitude of weight being transmitted through posterior column in cervical region; the present study noted that the area of articular facets increased in the cervical region as depicted in the above tables.

Pal and Routal (1987), stated that in upper thoracic region, weight is transmitted through two columns, one anterior similar to that in cervical region and one posterior formed by successive articulation of laminae at their articular facets together with their posterior ligamentous complexes and at the junction of cervicothoracic curvatures with the shifting of the line of gravity from posterior to anterior, a part of the posterior column weight is transferred to the anterior column through the pedicles.

The present study had observed maximum area of superior articular facets at T1 level in the cervicothoracic and upper thoracic region. Studies by Panjabi et al also showed the same change as shown in tables – 1and2. The above observation could be explained on the basis of the study by Pal and Routal (1986), that in addition to weight transmitted by the ribs, the laminae at T1 receive almost all the weight transmitted by the two posterior cervical columns.

According to Pal and Routal (1986,1987); the transfer of weight from posterior to the anterior column at T1/T2 is also supported by the fact that T1 and T2 facet areas are much greater than those of T5.

Thus the present study had noted that the articular facet areas at T1/T2 were more than the articular facet areas at the mid thoracic level.

The present study showed an increase in articular facet area in lumbar region with maximum facet area at L5. Panjabi et al also showed the same pattern as indicated by tables – 1,2,3and4. The above observation of the present study strongly supports and agrees with Pal and Routal (1986,1987); that as a result of shifting of load from anterior to posterior column in lumbar region, they had observed a gradual increase in articular facet area and lamina index from L1 to L5.

The overall area (A) of articular facets for Panjabi et al was more than the area (A) measured by the present study at all levels of vertebral column as seen in the above tables.

This is due to the fact that the average height of western population(on whom Panjabi et al has carried his study) is greater than Indian population and therefore the size of vertebral column also is more and hence the area of articular facets is more as compared to Indian population(present study).

The method employed by Panjabi et al was totally different from that by present study. Panjabi et al sought the use of computed radiographs; whereas, the present study measured each and every articular facets of vertebral column from C3 to S1 with the help of sliding vernier caliper, thread, scale.

The present study showed almost bilateral symmetrical readings of right and left sides at all vertebral levels (as shown in table-9), whereas the readings by Panjabi et al showed certain amount of bilateral asymmetry in readings on right and left sides of entire vertebral column.

The present study had indulged in manual measurements of dimensions of articular facets of 920 vertebrae and therefore the present study amounts to a huge collection of 40 spines (920 vertebrae) taken into study in contrast with the studies by Panjabi et al, as they studied only 276 vertebrae of the same bodies (12 spines).

Conclusion:

Because of shifting of weight from posterior column to anterior column at cervicothoracic curvature (Pal and Routal, 1986,1987) as discussed above, the present study had observed maximum area for superior articular facets in cervicothoracic region at T1 and for inferior articular facets at C7; as inferior articular facets of C7 will form zygapophyseal joint with superior articular facets of T1.

The present study had also observed the maximum facet area in the lumbar region at L5 because of transmission of weight (Pal and Routal,1986,1987) from anterior to posterior column in lumbar region.

The present study also observed that the width (W) of superior articular facets of lumbar vertebrae was more than its height (H) in contrast with the study by Panjabi et al.

Thus, the articular facets play an important role in weight transmission through the spine.

Hence in construction of model of spine to study the effects of injury and surgery on spine, huge sample size of spinal columns should be taken into account for measurements of articular facets which the present study had managed by providing parameters of articular facets of 40 spines (920 vertebrae).

The measurements obtained by the present study reveals the importance of articular facets in understanding the mechanics of spinal anatomy and its application with respect to transmission of weight.

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