362
`
`A Morphometric Study of Human Lumbar and
`Selected Thoracic Vertebrae
`
`JAMES L. BERRY, MS, JAMES M. MORAN, DEng, WILLIAM S. BERG, BS,
`and ARTHUR 0 . STEFFEE, MD
`
`The results of a morphometric study of selected human
`vertebrae undertaken to provide data for implant design
`are presented in this report. Twenty-seven dimensions
`were measured from thoracic (T2, T7, T12) and lumbar
`(L 1-LS) vertebrae using prepared spinal columns from 30
`skeletons belonging to the Hamann-Todd Osteological
`Collection. Maximum and minimum pedlcle dimensions in(cid:173)
`dicated that the pedicles are less symmetric cephalad than
`they are caudal. Vertebral body height increases caudally
`except posteriorly where, after an Initial increase, it de·
`creases in the lower lumbar region. Major and minor body
`diameters and the major spinal canal diameter slightly in·
`crease caudally, whereas minor spinal canal diameter ex·
`hibits little or no change. [Key words: vertebral morpho·
`metry, pedicle dimensions, Implant design]
`
`spinal processes in the intact spine. 10 All of the above-mentioned
`studies examined lumbar vertebrae, and some studied selected cer(cid:173)
`vica11.o.7.io.•• and thoracic6•9•12•13•16 vertebrae as well.
`The current study was undertaken d ue to a lack ofinfonnation
`needed for design projects involving instrumentation for the lum(cid:173)
`bar and thoracic vertebrae. Direct measurements were made of 27
`vertebral dimensions from prepared skeletal components. Radio(cid:173)
`graphs of cadaver specimens were also used to determine the cross(cid:173)
`sectional dimensions of the pedicles. Even though some of the mea(cid:173)
`suremenlS duplicate previous studies, they are included for
`comparative purposes, inasmuch as experimental techniques vary
`between investigators. Additionally, a wide variability has been
`reported between demographic groups. 11
`
`A CCU RA TE AN ATOMIC DESCR IPTIONS of vertebral shape are
`
`necessary for the development of implantable devices and
`spinal instrumentation. T he authors' interest in spinal im(cid:173)
`plants and fixation devices resulted in a need for more detailed
`morphologic and anthropometric data on the vertebrae than could
`be found in the existing literature.
`Several previous studies have investigated the morphometry of
`the vertebrae but through differing experimental techniques such as
`direct measurements, roentgenography with plain films, and CT
`7
`scans.2·3.1•
`11
`4 The studies also varied with regard to the ana(cid:173)
`8
`10
`·'
`•
`•
`•
`tomic structure of interest. Whereas some were strictly concerned
`with the morphometry of the vertebral body,i.3•7•9.io.u o thers con(cid:173)
`centrated on the dimensions of the spinal canal,'·3•1•8•11 transverse
`process,14 and pedicle.6•9•12•14•16 Additional measurements receiving
`11 and the angle between
`scrutiny include interpedicular distance4
`•
`the facet joints and lamina.'5 Nissan et al performed a multifaceted
`analysis which, in addition to body shape, described vertebral
`length, the spinous process, disc size, and the distance between
`
`From the Cleveland Research Institute at St. Vincent Charity Hospital
`and Health Center, Oeveland, Ohio.
`Submitted for publication June 27, 1986, and revised August 2, 1986.
`The authors thank Eileen Morgan, for technical assistance, Mary Hank,
`for typing the manuscript, and Bruce Latimer, of the Cleveland Museum of
`Natural History, who graciously provided access to the Hamann-Todd col(cid:173)
`lection.
`
`MATERIALS AND METHODS
`D irect dimensional measurements were obtained from contem(cid:173)
`porary human skeletons belonging to one of the most extensive
`skeletal collections in the world, the Hamann-Todd Osteological
`Collection at the Cleveland Museum of Natural History in Cleve(cid:173)
`land, Ohio, which houses more than 3,000 skeletons with accompa(cid:173)
`nying autopsy reports. In some instances medical histories are also
`available.
`Vernier and outside dimension calipers were used to measure the
`bone geometry (precision: . I mm). Angular measurements were
`taken with a goniometer (precision: 1°). For the sake of consist(cid:173)
`ency, all measurements were taken by the same observer. The lum(cid:173)
`bar (LI - LS) and three thoracic (T2, TI, Tl 2) vertebrae of ran(cid:173)
`dom ly selected normal Caucasian male and female skeletons were
`studied. The sample population consisted of five m en and five
`women from each of the fifih through seventh decades oflife for a
`total of 30 skeletons, or 240 vertebrae. Skeletons having gross evi(cid:173)
`dence of congenital or acquired vertebral pathology and/or written
`documentation (autopsy report) of bone abnormalities such as
`tumors, fractures, or arthritis were excluded from this study.
`With present a nd future applications in mind, virtually the entire
`geometry of the vertebrae was quantified by recording a total of 27
`measurements per vertebra. Complete descriptions of the mea(cid:173)
`sured parameters are presented in Figures I -3. Three of these mea(cid:173)
`surements (the angle between the pedicle and the body, the cross(cid:173)
`sectional dimensions of the pedicle, and the distance through the
`pedicle and body) primarily pertain to pedicle screw fixation and
`are reported in greater detail elsewhere. 9
`
`
`
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`

`STUDY OF SELECTED VERTEBRAE • BERRY ET AL 363
`
`RESULTS
`The means and standard deviations of the dimensional data for
`all 240 vertebrae are presented in Table I. To narrow the scope of
`the article, and simplify presentation of the results, thedata for the
`males and females at all ages have been combined. Note that even
`with this simplification the data remain consistent, with the coeffi(cid:173)
`cients of variation being generally less than I 0%.
`The average maximum and minimum pedicle dimensions for
`the entire population are presented in Figure 4. Maximum and
`minimum dimensions were obtained for two pedicles per body,
`thus the data in Figure4 represent both the rightand left pedicle for
`each vertebra. The relative differences between the maximum and
`minimum dimensions demonstrate that the pedicles are less sym(cid:173)
`metric cephalad and become more so caudad. The minimum di(cid:173)
`mensions correlate well with those reported in other recent stud(cid:173)
`ies. 1J,16
`A consistent trend is seen between vertebral body height and
`level (Figure 5). Three offourdimensions(anterior, posterior, right,
`and left height) increase progressively from T2 to LS. The posterior
`measurement levels off and then slightly decreases in the lumbar
`region. This is probably due in part to the lumbar curvature be(cid:173)
`tween L4 and SJ. The data are in agreement with Nissan et at. 10
`However, Postacchini et al 11 reported a single height measurement
`which did not reflect the decrease.
`Major and minor body diameters were also plotted as a function
`oflevel (Figure 6). With the exception of the major diameter at T7,
`both dimensions exhibit slight increases caudally. Several other
`authors have reported similar findingsu.s.u.i4 although only lum(cid:173)
`bar vertebrae were measured.
`The dimensions of the spinal canal were also correlated to verte(cid:173)
`bral level (Figure 7). As with body height, the major spinal canal
`diameter increased caudally, with the exception of T7. Minor di(cid:173)
`ameter showed little or no change between T2 and LS. Postacchini
`et al' 1 and Eisenstein et al2 reported similar data.
`The anterior, posterior, right, and left body heights of all the
`vertebrae were averaged, and the total for each spinal column was
`plotted against the body height measured at autopsy. No correla(cid:173)
`tion was found (r2= .006). No attempt was made to relate weight to
`
`s
`
`R
`
`Fig 3. Description of vertebral measurements taken from the sagittal view
`of the vertebrae. Body height was measured along the mkfsagittal plane,
`(P) anteriorly and (Q) posteriorly. Length of the vertebrae was measured
`from the most anterior aspect of the body to the most posterior aspect of
`the spinous process (R). Body descent angle was defined as the angle
`between the superior surface of the body and a plane pa(ailel to the inferior
`surface($). Angte of declination of the spinous process was defined as the
`angle between the plane bisecting the spinous process and the plane
`parallel to the body's inferior surface (T). Major dimensions (G) of the right
`and left pedicles were measured regardless of orientation. The mldline (BJ
`minor body diameter was measured a sagittal line bisecting the vertebral
`body and spinous process.
`
`
`
`Fig 1. Description of vertebral measurements taken from the superior(cid:173)
`inferior aspect. Major body diameter was measured along a frontal line
`bisecting the vertebral body and spinous process, (A) at the most superior
`level, (B) at the midline, and (C) at the most Inferior level. Minor body
`diameter was measixed along the midsagittal plane, (D) at the most supe·
`rior level. (E) at the midllne, and (F) at the most inferior level. Minor (H)
`dimensions of the right and left pedicles were measured regardless of
`orientation. Pedicle angle (I) was defined as the angle formed between the
`midsagittal plane and the plane bisecting the pedicle. Pedicular screw path
`lengths through the pedicie's center into the body to a point at the anterior
`border of the body's center were measured by two ditterent approaches:
`(J) a straight path parallel to the midline bisector of the pedicte and (K) an
`oblique path representing the largest permissible deviation from this line.
`Minor spinal canal diameter (L) was measured along the midsagittal plane.
`Major spinal canal diameter (M) was measured along the frontal plane
`passing through the canal's midpoint.
`
`Fig 2. Description of vertebral measurements taken from the posterior -
`anterior view of the vertebrae. Height of the vertebrae was measured from
`the most superior aspect of the superior articular process to the most
`inferior aspect of the inferior articular process (N). Body height was mea·
`sured along the frontal plane through the widest part of the body at the left
`and right lateral borders (0). The midline (E) major body diameter was
`measured along the frontal plane.
`
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`

`384 SPINE • va.UME 12 • NUMSCR 4 • 1987
`
`Table 1. Mean and Standard Deviations for a Total of 240 Vertebrae, 30 et Each Level
`
`Measurement
`
`T2
`
`17
`
`T12
`
`L1
`
`L2
`
`L3
`
`L4
`
`LS
`
`A
`B
`c
`0
`E
`F
`G
`
`Right
`Left
`H
`Right
`Left
`
`Righi
`Left
`
`Right
`Left
`
`J
`
`K
`
`Right
`Left
`L
`M
`N
`Right
`Left
`
`0
`
`Right
`Left
`p
`a
`R
`s
`T
`
`29.8± 2.4
`26.1 ± 2.5
`33.5± 2.9
`16.1 ± 1.5
`17.5 ± 1.7
`19.0± 1.6
`
`11 .7 ± 1.2
`11.9± 1.3
`
`6.1 ± 1.2
`6.3± 1.0
`
`23 ± 6
`23 ± 6
`
`31.± 2.8
`28.0± 2.9
`33.2± 3.2
`27.0 ± 3.3
`26.1± 3.2
`28.0 ± 3.6
`
`43.8± 3.3
`37.6± 3.2
`46.8± 3.!!
`31 .7± 4.4
`29 .. 2± 3.4
`31.2± 3.9
`
`45.2± 4.6
`39.5± 3.6
`49.1 ± 3.7
`31 .9± 3.7
`28.9± 3.5
`32.3± 3.5
`
`47.7 ± 4.7
`44.8± 3.1
`54.8 ± 4.8
`33.3±3.7
`29.9± 3.3
`33.4 ±3.4
`
`49.6±3.2
`42.3± 3.5
`53.8 ± 3.7
`33.9±3.3
`31.6± 3.3
`34.2 ±3.3
`
`51 .2 ± 5.6
`40.8 ± 3.2
`50.9±4.6
`34.9 ± 3.4
`32.5±2.9
`35.6 ±3.1
`
`53.4± 4.4
`46.1 ± 4.5
`52.7± 4.3
`35.1 ± 2.8
`32.4± 2.8
`34.5± 3.0
`
`12.1 ± 1.0
`11.9± 1.0
`
`17.2 ± 1.6
`17.0± 1.3
`
`15.6± 1.4
`15.6± 1.5
`
`15.4± 1.0
`15.2±1.0
`
`14.6±1.2
`14.3± 1.0
`
`13.0± 1.3
`13.2± 1.4
`
`13.8± 2.5
`13.6± 2.8
`
`5.1 ± 1.4
`4.8± 1.4
`
`7.7± 2.1
`7.6± 1.5
`
`7.0 ± 1.9
`6.9± 1.7
`
`7.4 ± 1.6
`7.5± 1.5
`
`9.2±1.3
`9.1 ± 1.6
`
`10.3±1.6
`10.4 ± 1.6
`
`10.9± 3.4
`10.5 ± 2.9
`
`8 ± 4
`7 ± 5
`
`- 5 ± 8
`-1 ± 10
`
`6 ± 8
`9 ± 7
`
`11 ± 3
`12 ±3
`
`14 ± 4
`14 ±4
`
`20 ±5
`20 ±4
`
`32 ± 5
`31 ± 5
`
`26.4 ± 2.4
`27.1 ± 2.0
`
`36.2± 3.2
`36.3± 4.2
`
`38.8± 3.8
`38.8± 3.8
`
`42.1 ± 3.8
`40.2± 3.4
`
`45.2± 38
`46.5±3.5
`
`45.0 ± 3.3
`45.7 ±3.7
`
`44.0±2.9
`45.6±3.9
`
`30.3± 2.3
`32.1 ± 2.0
`15.0± 1.3
`18.3± 1.5
`
`31 .6± 2.0
`31.7 ± 2.0
`
`17.9± 1.4
`17.7 ± 1.2
`17.6 ± 1.2
`16.5± 1.2
`64.1 ± 4.6
`136 ±21
`137 ±21
`
`40.7 ± 3.2
`42.0± 4.0
`16.6 ± 5.0
`17.1 ± 5.1
`
`34.0± 5.1
`33.0± 5.6
`
`19.9 ± 1.8
`20.2± 3.5
`18.7 ± 2.8
`19.1 ± 1.6
`63.9± 8.6
`110 ±30
`110 ±31
`
`44.0± 5.0
`46.9± 4.9
`17.2± 1.9
`20.2± 2.3
`
`47.5± 4.4
`49.8± 3.7
`17.2 ± 1.3
`22.1 ± 2.3
`
`50.5±4.0
`53.1±3.8
`16.0± 2.6
`23.0± 2.3
`
`49.0 ± 3.5
`52.0±3.5
`16.2 ±2.6
`22.7±1 .7
`
`49.5±3.2
`53.2±3.8
`16.1±1.5
`22.0 ± 1.8
`
`45.5± 2.8
`45.2± 2.9
`
`47.6± 3.7
`47.3± 3.7
`
`45.2±3.6
`44.8± 4.6
`
`48.0 ± 3.2
`48.6±3.3
`
`48.5±2.7
`49.1±3.5
`
`24.2 ± 1.7
`23.9± 1.5
`23.4 ± 2.0
`24.8 ± 1.8
`73.4 ± 11 .0
`20 ± 7
`20 ± 7
`
`25.6± 1.6
`24.9± 1.6
`25.0± 2.9
`25.8± 2.1
`79.9 ± 6.3
`21 ± 19
`18 ± 6
`
`27.3± 1.5
`27.7 ± 1.8
`27.9± 1.9
`25.2±2.2
`85.0± 5.8
`14 ±3
`14 ±4
`
`26.5± 1.7
`26.5± 1.7
`27.4 ± 1.7
`26.0 ± 1.6
`85.6±6.0
`17 ±5
`17 ±5
`
`25.7 ± 1.3
`25.7±1.3
`26.7 ± 1.5
`26.4 ± 1.7
`63.4 ± 5.5
`14 ±4
`14 ±3
`
`40.8± 3.2
`40.3± 4.0
`
`47.8± 3.5
`50.9± 4.3
`17.3 ± 2.9
`26.0 ± 2.5
`
`41.5± 4.4
`42.2± 3.7
`
`27.0± 1.8
`27.0± 1.7
`28.7 ± 1.9
`23.1 ± 1.5
`74.1 ±15.3
`20 ± 6
`20 ± 6
`
`Pedicle Diameter (mm)
`20
`
`15
`
`10
`
`5
`
`~Minimum
`~Diameter (HJ
`
`II Maximum
`
`Diameter (G)
`
`T2
`
`T7
`
`T12
`
`L1
`L2
`Vertebral Level
`Fig 4. Minor (H) and major (G) pedicle diameters. means of 15 each males and females, fifth through seventh decades.
`
`L3
`
`L4
`
`L5
`
`
`
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`

`STUDY OF SELECTED VERTEBRAE • BERRY ET AL 365
`
`Body Height
`30
`
`(mm)
`
`25
`
`20
`
`15'--1--~~..L-~~....l..-~~-'-~~-L.~~--'-~~__J~~~.I..-
`T7
`T2
`T12
`L1
`L4
`L2
`L3
`L5
`Vertebral Level
`Fig 5. Body height (O,P.0) versus vertebral level, combined data for all specimens studies.
`
`Body Diameter
`60
`
`(mm)
`
`ANTERIOR
`
`(P)
`
`POSTERIOR
`
`(Q)
`
`RI GHT
`
`(0)
`
`LEFT
`
`(0)
`
`MINOR
`
`(0, E, Fl
`a
`
`r--------" _________ ,, ________ ... ---------.a----------0
`
`///
`/
`e.----e--------~--~ir----e
`~
`
`!ll---------.a'
`
`MAJOR
`
`(A, B, C)
`
`----e----
`
`55
`
`50
`
`45
`
`40
`
`35
`
`30
`
`25
`
`20
`
`T2 ·
`
`T7
`
`L2
`L1
`Vertebral Level
`Fig 6. Body diameter versus vertebral level. Points represent means of superior (A,D), midtine {B,E) and Inferior {C,F) measurements for all specimens
`studied.
`
`T12
`
`
`
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`

`366 SPINE • VOLUME 12 • NUMBER 4 • 1987
`
`Canal Diameter
`25
`
`(mm)
`
`(Ml
`
`MAJOR
`e
`
`MINOR
`(L)
`----El----
`
`T2
`
`T7
`
`T12
`
`L2
`L1
`Vertebral Level
`Fig 7. Major (M) and minor (l) spinal canal diameters versus vertebral level, combined data for an specimens studied.
`
`L3
`
`L4
`
`L5
`
`cross-sectional dimensions, since many of the weights at autopsy
`appeared low relative to the height. This was possibly indicative of
`dehydration or decomposition of the cadaver or perhaps malnutri(cid:173)
`tion during life.
`
`DISCUSSION
`The overall goal of this study was to generate information that
`would be useful for geometric modeling of the vertebrae. Such
`information has numerous potential applications. Biomechanical
`and ergonomic analyses of the spine frequently have need of spinal
`dimensions as input. Although specific requirements vary, it is
`hoped that these data on spinal morphometry are general enough to
`be useful to a variety of studies.
`The authors' immediate need was in the design of spinal instru(cid:173)
`mentation. The application to pedicle screw fixation is outlined
`elsewhere,9 and a total vertebra replacement has also been de(cid:173)
`signed. For the one total vertebra that has been implanted, the data
`were used only to double check dimensions scaled from computed
`tomography (CT) scans. Agreement between the patient's CT data,
`average skeletal data, and one skeleton whose living dimensions
`closely matched the patient's own size, was extremely good. The
`artificial vertebra could thus be made to duplicate the geometry of
`the replaced vertebra. In instances where destruction of the vertebra
`is more extensive, due to trauma or gross invasion by a tumor, the
`data will be necessary for sizing the replacement and reconstructing
`normal alignment.
`Through comparison of the results with other studies of spine
`geometry that have used CT scanning, and our own CT work for
`vertebral replacement, it is apparent that CT scanning can be a
`useful tool for evaluating spinal geometry in vivo. However, proper
`care must be exercised in regard to factors such as slice thickness,
`scan diameter, calibration standards, and orientation of the scan(cid:173)
`ning plane relative to the anatomic stflJcture of interest. The cur-
`
`rent data might also be applied to the detection ofaoatomic abnor(cid:173)
`malities by comparison of CT scans with the population averages.
`
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`STUDY OF SELECTED VERTEBRAE • BERRY ET AL 367
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`14. Van Schaik JJP, Verbiest H, van Schaik FDJ: Morphometery of lower
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`Address reprint requests 10
`
`James M. Moran, DEng
`Direclor of Muscu/oskeleta/ Research
`2351 East 22nd Slreet
`Cleveland, OH 44115
`
`Accepted for publication November 10, 1986.
`
`
`
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`