THE EVALUATION OF GEOMETRIC
PARAMETERS OF LUMBOSACRAL VERTEBRAE (A RADIOGRAPHIC STUDY)
CHAPTER ONE
INTRODUCTION
1.1 BACKGROUND OF THE STUDY
The vertebral spine presents
regional curves on sagittal plane designed to absorb impact, reduce its
longitudinal stiffness and intensify muscular function (Gelb et al., 1995).
Values of sagittal curve measurements on spine present great variability in
normal individuals often with a wide range of variation. The lumbosacral region
is the most important region in the vertebral column in terms of mobility and
weight bearing. It is lordotic in the cervical and lumbar vertebrae, and
kyphotic in the thoracic and coccygeal vertebrae. However, pathological
conditions can alter these curvatures. The correlation between lumbosacral
geometry and the incidence of low back pain has been established (Azar et al.,
2009; Evcik and Yucel 2003; Sarikaya et al., 2007). The shape of the
lumbosacral spine has been reported to be of importance in the occurrence of
the low back pain (Lord et al., 1997; Fernand and Fox 1985).
Low back pain (LBP) is a highly
common problem and causes much morbidity and socio-economic loss in the
community (Dincer et al., 2007) with a lifetime incidence of between 50% and
90%. Therefore evaluation of the lumbosacral geometry is one parameter that is
of importance in evaluating the possible etiology of low back pain (Lord et
al., 1985). The radiographic parameters evaluated during an assessment of the
lumbosacral vertebrae are:
⦁ Lumbosacral Angle (LSA),
⦁ Lumber Lordosis Angle (LLA),
⦁ Sacral Inclination Angle (SIA) and
⦁ Lumbosacral Disc Angle (LSDA).
Some studies have reported
significant associations between some of the radiographic parameters and
certain demographic and anthropometric factors (Lord et al., 1997; Fernand and
Fox 1985; Amonoo-Kuofi 1992). However, the literature is still ambivalent with
respect to an association between these radiographic parameters and certain
anthropometric and demographic factors.
1.2 AN OVERVIEW OF THE RELEVANT BONY ANATOMY OF THE LUMBAR SPINE
AND SACRUM.
1.2.1 Vertebral Column:
The vertebral column also referred
to as the human spine is a curved linkage of individual bones or vertebrae. It
is a very complicated musculoskeletal structure containing various soft and
hard tissues. The vertebral or spinal column is a composite anatomical
structure made of a string of 33 bones each known as a vertebra. They are
connected by a mass of cartilage called inter-vertebral disc. The vertebral
column is also the attachment site of various spinal muscles and ligaments
which provide the structural stability of the entire vertebral column. The
spinal canal located in the posterior region of the vertebral column functions
as a protective shell of the delicate spinal cord. The adult vertebral column
consisting of 33 vertebral segments accounts for approximately 48% of the
overall body length. Although the usual number of vertebrae is 7 cervical, 12
thoracic, 5 lumbar, 5 sacral and 4 coccygeal, this total is subject to frequent
variability, and there have been reports of variation between 32 and 35 bones.
The sacral region consists of 5 fused vertebrae while the coccygeal region is
made of 4 fused vertebrae. A typical vertebra has a ventral body, a dorsal
vertebral (neural) arch, extended by lever-like processes, and a vertebral
foramen, which is occupied in life by the spinal cord, meninges and their
vessels (Andrew Williams et al., 2004).In keeping with the geometrical features
of the vertebrae, the vertebral column is divided into five sections (fig 1.1),
namely;
⦁ Cervical region
⦁ Thoracic region
⦁ Lumbar region
⦁ Sacral region
⦁ Coccygeal region
Image
Fig. 1.1 The vertebral column (Ming
2004).
1.2.2 The Lumbar Spine
The Lumbar region is situated in
the lower back between the thoracic region and the sacrum. It usually has five
vertebrae (L1 – L5). Each vertebra has 2 basic parts: the vertebra body (VB)
and the neural arch. The human Lumbar vertebrae support weight of the upper
body. They have the largest vertebral bodies in the spinal column. This region
has been under the focus of intensive research because it is the main
load-bearing region of the entire vertebral column, and its abnormality
contributes to the development of an array of pathological symptoms such as low
back pain.
⦁ The Vertebral body (VB): The
lumbar vertebral body is wider transversely and has the shape of a kidney in
cross section. From birth to 5 years, it increases in height from 5mm to 18mm.
It then increases to 26mm between 5-13 years of age, and to 34mm in adulthood
(Bogduk 2005). The vertebral foramen which is oval in shape contains the spinal
cord and the cauda equine.
Image
Fig 1.2 Segment of the vertebral
column – lumbar region (Ming 2004).
⦁ The Neural Arch: This is also
known as the posterior element and is a general term used to refer to the
remaining components of the lumbar vertebra that are posterior to the vertebral
body. As shown in fig 1.4, these components include:
⦁ Pedicles; that connects the lamina
to the upper part of the vertebral body.
⦁ Laminae; a flat plate acting as
the posterolateral wall of the spinal canal on each side.
Image
Fig 1.3 Side view of the Lumbar
spine.
(Standring: Gray’s Anatomy 39e –
wwwgraysanatomyonlinecom)
⦁ Transverse processes;that extend
laterally from the junction of the laminae and pedicles and provides
attachments for the inter-transverse ligaments and muscles.
⦁ Spinous process;that protrudes
posteriorly from the junction of the left and right laminae, and provides
attachment site for the supraspinous and interspinous ligament.
⦁ Superior and inferior articular
facets; the inferior articular facet of the superior lumbar vertebra and the
superior articular facet of the inferior lumbar vertebra, on each side, form a
synovial joint called apophyseal joint.
Image
Image
Fig 1.4 Components of the Neural
arch (Ming 2004).
1.2.3 The Sacrum
The Sacrum is made up of five
bones/vertebrae. The five sacral vertebrae (S1 – S5) fuse to form the
triangular sacrum. It is located between the lumbar vertebrae and the coccyx.
The base of the sacrum (sacral promontory) is angled anteriorly and inferiorly
and is formed by the superior surface of the first sacral segment (S1). The
spinous processes are fused in the midline to form the median sacral crest. The
dorsal foraminae lie laterally to the fused spinous processes.
Image
Fig. 1.5 The anterior and posterior
views of the Sacrum. © Elsevier Ltd 2005. (Standring: Gray’s Anatomy 39e –
wwwgraysanatomyonlinecom)
The sacrum is a key component in
the human body and certainly deserves its name: sacred/holy bone. Therefore its
position and orientation dictates much of the vertebral column’s form, shape
and stability. It is also part of the pelvic girdle: transferring the weight of
the upper body to the legs, supporting the body in walking and allowing
considerable elasticity in child-bearing. Therefore, the sacral inclination is
of considerable anthropological and clinical importance.
As a result of the sacral
inclination, an individual maintains an erect posture by developing a lordotic
curve in the lumbar spine in order to compensate for the angulations of the
sacrum (Bogduk 2005; Middleditch and Oliver 2005).
Image
Image
Fig 1.6 Well-detailed Anterior and
posterior views of the Sacrum.
(© Elsevier Ltd 2005. Standring:
Gray’s Anatomy 39e – wwwgraysanatomyonlinecom)
1.3 LUMBOSACRAL JUNCTION
The Lumbosacral vertebrae refers to
the articulations between the fifth lumbar and first sacral vertebrae (Andrew
Williams et al., 2004). The bodies are united by a symphysis which includes a
large vertebral disc. The latter is deeper at the lumbosacral angle. The
synovial facet joints are separated by a wider interval than those found in the
vertebra above.
1.4 CURVATURES OF THE VERTEBRAL COLUMN
The vertebral column presents
regional curves on sagittal plane designed to absorb impact, reduce its
longitudinal stiffness and intensify muscular function (Gelb et al., 1995).
There are four curves: cervical, thoracic, lumbar and sacral curvatures. The
primary curvatures that develop during foetal period are the thoracic and
sacral curvatures which are concave anteriorly and convex posteriorly, and are
termed kyphotic curves.
Image
Fig 2.8 Spinal column curvatures
(© Elsevier Ltd 2005. Standring:
Gray’s Anatomy 39e – wwwgraysanatomyonlinecom)
The cervical and lumbar curves are
convex anteriorly and concave posteriorly (lordotic curves) and are secondary
curves that commence during the foetal period and becomes obvious at infancy.
The lumbar lordosis appears as the child begins to stand and later walk. It
increases till adulthood. It develops as a secondary curve and enables the
spinal column to transmit the weight of the trunk to the pelvis so that little
muscle effort is needed to maintain an erect posture (Anson et al., 1971;
Willner and Johnson 1983).
Image
Fig 2.7 Normal curvature of
Vertebral column and regions.
(© Elsevier Ltd 2005. Standring:
Gray’s Anatomy 39e – wwwgraysanatomyonlinecom)
The lumbosacral curvature could be
affected by conditions such as age, posture, degeneration, inflammation, trauma
or surgery. Of these, the aging process plays the major role (Gelb et al.,
1995; Azar et al., 2009). The magnitude of lumbosacral curves is associated
with various causes of low back pain (Azar et al., 2009; Evcik and Yucel 2003;
Sarikaya et al., 2007; Murrie et al., 2003; Nodrin et al., 1991). Furthermore,
lumbosacral lordosis plays a very important role in spine surgery. Loss of
lordosis after instrumented spinal fusion often results in sagittal spine
misbalance and persistent back pain, so-called ‘flat-back syndrome’ (Moskowitz
et al., 1980; Swank et al., 1990). Measures must be put in place to preserve
the lordosis during spine surgery.
1.5 AIM OF THE STUDY
The aim of this study was to
evaluate the radiographic measurements of geometric parameters of the
lumbosacral vertebrae of adults in Edo state.
1.6 OBJECTIVES OF THE STUDY
The specific objectives included:
1. To measure the geometric
parameters of the lumbar spine: LSA, LLA, SIA, LSDA.
2. To evaluate the relationship of
various geometric parameters of the lumbosacral vertebrae with age, gender and
occupation.
3. To determine any relationship
between the geometric measurements and some anthropometric indices.
4. To determine the relationship
between the geometric parameters of the lumbosacral spine, and adiposity and
other anthropometric indices.
5. To establish prediction formulae
for the geometric parameters using anthropometric indices.
1.7 STATEMENT OF PROBLEM/RATIONALE FOR THE STUDY
Low back pain (LBP) is a major
public health problem all over the world. It affects 60-80% population of USA
adults at some time in their life, and as many as 50% have pain within a given
year, with enormous socio-economic burden (Leibenson et al., 1992; Frymoyer et
al., 1998; Frymoyer et al 1992; Nodrin et al., 1991). It has continued to be a
source of difficulty for patients, physicians, therapists and for the society.
Identifying subgroups with regard to risk profile as well as specific treatment
options has become a major research interest (Bonter et al., 1998). It is
pertinent that if subjects with modifiable risk profiles for LBP can be
identified then prophylactic measures could be instituted to prevent the development
of this major public health and socio-economic problem.
The sacrum is part of the vertebral
column and forms the base on which of the spine is erected. Therefore, its
size, position and orientation dictate much of the vertebral column’s stability
and have great clinical implications.
The relationship between
lumbosacral angles and low back pain has been described by various studies
(Azar et al., 2009; Evcik and Yucel 2003; Sarikaya et al 2007; Murrie et al.,
2003; Jackson et al., 1994). Identifying individuals with demographic and
anthropometric variables that are associated with specific lumbosacral angles
could predict individuals at risk of developing mechanical low back pain.
1.8 SCOPE OF THE STUDY
The data of 300 subjects who met
all the inclusion criteria were analysed. The subjects were informed of the
nature of this study and each one gave consent for the study. All the subjects
had their height, weight, waist and hip circumferences measured. The lateral
radiograph of the lumbosacral spine was taken for each subject in the supine
position. The radiographs were then evaluated for selected radiographic
parameters.
1.9 LIMITATION TO THE STUDY
The objectives of this research may
not be perfectly or accurately realized due to the following limitations;
⦁ Disinclination of people in
participating in research work.
⦁ Difficulty in gaining access to
the facilities in the radiological clinics.
⦁ Refusal to sign the consent form
by participants.
⦁ Age factor; which prevented
individuals below 18 to participate due to their parent’s and guardian’s
refusal to consent.
CHAPTER TWO
LITERATURE REVIEW
INTRODUCTION
Wilhelm Conrad
Roentgen accidentally discovered x-rays in 1895 while conducting some
experiments in his laboratory (Yochum and Rowe 2005). The “X” in x-rays
represented the unknown ray as Roentgen did not know what to name the invisible
rays. One of the significant aspects of this discovery was the development of
the clinical radiography which allows us to “see” the internal structures of
the body especially bony tissue. Although the x-ray was considered an excellent
diagnostic imaging tool, the harmful aspect of radiation could not be ignored
(Yochum and Rowe 2005). Since its discovery, it has been of immense value in
the evaluation of skeletal disorders (Yochum and Rowe 2005; Kendrik et
al., 2001). Most patients requiring medical attention for low back pain
have routine x-rays taken of the lumbosacral spine as part of the initial
evaluation. The radiographs may be evaluated utilizing the ABCS approach (A =
Alignment; B = Bone; C = Cartilage; S = Soft tissue). Routinely two views are
taken anteroposterior (AP) and lateral (L) views. Igbinedion and Akhigbe (2011)
recorded that transition vertebrae cause low back pain. Transition vertebrae
involved the downward migration of L5 (sacralisation) or upward
migration of S1 (lumbarisation) (Igbinedion and Akhigbe, 2011).Igbinedion
and Akhigbe (2011); Osunwoke et al., (2009), however, recorded that
32.3% of their patients had transitional vertebrae, of which 5.9% had
lumbarisation and 26.4% sacralisation. In that same study, 2.4% males and 3.6%
females had lumbarisation and 15.7% males and 10.7% females had sacralisation.
In the study recorded by Uduma et al., (2013), lumbarisation was seen
in four cases (7.02%) with equal male to female ratio. The earliest age of
discovery was 4th decade. This late presentation of an anatomical
variant is probably due to its asymptomatic nature. Symptomatology, therefore,
arose on receipt of secondary spondylosis. However, Igbinedion and Akhigbe
(2011), did not observed any statistical correlation between transitional
vertebrae with sex, age group, body mass index, osteophyte formation, vacuum
phenomenon, disk degeneration, and spondylolisthesis. Measurement of the lumbar
spine radiographic parameters may be useful in the investigation of low back
pain (Amonoo-Kuofi 1992) and in the design and development of spinal implants
and instrumentation (Zhou et al., 2000).
The radiographic
parameters evaluated during an assessment of the lumbosacral vertebrae are:
- Lumbosacral
angle (LSA)
- Lumbar
lordosis angle (LLA)
- Sacral
Inclination angle (SIA)
- Lumbosacral
disc angle (LDA)
Lumbosacral Angle
(LSA): Lumbosacral angle is also known as sacral base angle (SBA) or
Ferguson’s angle (Yochum and Rowe 2005). There is very little research
available on the precise causes of LSA alterations and the effects on spinal
biomechanics. The available data often differ in opinion. Chung et al., (1981)
in a study on 132 symptomatic Korean males and females reported that males have
a slightly greater LSA than females. On the contrary, Fernand and Fox (1985)
reported a significantly higher mean LSA in females; the males had a mean LSA
of 43.3° while the females had a mean of 47.2°. However, Rosok and Peterson
(1993) noted no difference in the mean LSA between males and females. LSA was
noted to be greater in females who had a history of previous pregnancy than
females who had no offspring (Bryner and Moussali 1992). Middleditch and Oliver
(2005) reported that the LSA is greater in females during child-bearing years
than in post-menopausal females and the difference was presumed to be due to
hormones. Few studies have examined the effects of body type and size on LSA
(Andrews et al., 2001; Brunaugh et al., 2002). There is
paucity of data on the effects if obesity and excess body fat distribution on
LSA. Andrews et al., (2001) reported no correlation between BMI and
LSA. This study was however said to be unreliable due to its inability to
differentiate between abnormal BMI and WHR. Ridola et al., (1994)
noted that in the obese individual, the weight of the trunk at the base of the
sacrum is displaced anteriorly. This displacement will cause the pubis to
rotate posteroinferiorly, while the sacrum tends to rise superiorly and assume
a more horizontal orientation thus increasing the LSA. Brunaugh et al., (2002)
noted a significant correlation between BMI and WHR, and LSA. A wide range of
variation in this measurement has been noted. Yochum and Rowe (2005) reported a
range of 26 - 57º with a mean of 41º ± 7º. They also noted that the value
increases from the recumbent to upright position by 7 - 12º. Kim et al., (2006)
noted a normal value of 39.8º ± 8º with a range of 11 - 58º. These findings
show that the LSA varies widely among individuals. There is no consensus of
opinion on the significance of either a decreased or an increased LSA. An
increased angle has been implicated as a mechanical factor in low back pain by
increasing shearing and compressive forces on the lumbosacral posterior joints
(Bogduk 2005; Yochum and Rowe 2005).