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.
.