Project – Morphometric Analysis of the Lumbar Vertebrae and Its Relevance to Spinal Surgery: A CT-Based Study at IMSUTH

CHAPTER ONE

INTRODUCTION

1.1 Background to the Study

The lumbar vertebral column constitutes the lower portion of the human vertebral column and consists of five vertebrae designated L1 to L5. The lumbar vertebrae are structurally adapted to withstand substantial axial loading and provide stability while permitting controlled movement of the trunk. Each lumbar vertebra possesses a vertebral body, vertebral arch, pedicles, laminae, transverse processes, spinous process and superior and inferior articular processes, with progressive changes in size and configuration occurring from the upper to the lower lumbar levels. The pedicles are particularly important because they connect the vertebral body to the posterior elements and provide the osseous corridor through which pedicle screws may be inserted during spinal fixation. Consequently, accurate knowledge of lumbar vertebral morphology and dimensions is fundamental to understanding spinal biomechanics, radiological anatomy and surgical treatment of lumbar spinal disorders (Standring, 2021; Bonczar et al., 2025).

Morphometry provides a quantitative approach to the study of the lumbar vertebrae by determining measurements such as vertebral body dimensions, spinal canal dimensions, pedicle width and height, pedicle length, transverse and sagittal angulation, and interpedicular distance. These measurements are important because the dimensions of the lumbar vertebrae are not uniform across all vertebral levels or individuals. A recent systematic review and meta-analysis of 1,481 individuals demonstrated progressive changes in the lumbar spinal canal and transverse processes from L1 to L5 and identified substantial level-specific differences in pedicle dimensions. The authors emphasized that such normative morphometric information is relevant to procedures including pedicle screw fixation, percutaneous endoscopic transforaminal discectomy and lumbar disc replacement (Bonczar et al., 2025).

The pedicles are among the most clinically important components of lumbar vertebral morphology because they serve as the principal bony pathway for transpedicular screw fixation. Successful screw placement requires adequate knowledge of pedicle width, height, length and orientation so that an appropriately sized implant can be selected and directed through the pedicle without breaching its cortical boundaries. A systematic review of lumbar pedicle morphometry reported considerable differences in pedicle width and height between vertebral levels and across geographical populations, indicating that anatomical measurements obtained from one population may not necessarily be directly applicable to another. Such variations have implications for the selection of implant dimensions and the planning of spinal instrumentation (Li et al., 2023).

Computed Tomography (CT) has become an important modality for evaluating the bony anatomy of the lumbar spine because it provides high-resolution cross-sectional images that permit detailed assessment of vertebral structures. Multidetector CT and multiplanar reconstruction can demonstrate the pedicles, vertebral body, spinal canal, transverse processes and other osseous landmarks with considerable precision. CT-based morphometry also permits measurements to be obtained in living individuals without the limitations associated with measurements made exclusively from isolated dry bones. Previous radiological research has therefore employed CT to investigate lumbar pedicle dimensions and angles and to provide information useful for preoperative spinal planning (Patel et al., 1988; Nkwerem et al., 2024).

The dimensions of the lumbar pedicles also demonstrate population-related variation. In a CT-based study of 273 adults from South-Eastern Nigeria, Nkwerem et al. (2024) reported level-specific differences in longitudinal and transverse pedicle dimensions, maximum length of purchase and pedicle angulation. Their findings showed that transverse pedicle diameter increased considerably toward the lower lumbar levels, while several measurements demonstrated significant relationships with sex. The researchers noted that accurate preoperative knowledge of pedicle dimensions is necessary for reducing complications associated with transpedicular fixation. These findings are particularly relevant to the present study because they demonstrate that Nigerian populations require locally generated morphometric information rather than relying entirely on measurements derived from other racial or geographical populations (Nkwerem et al., 2024).

Sex and age are additional factors that may influence lumbar vertebral morphology. Differences in skeletal dimensions between males and females have been reported in several morphometric studies, while age-related changes may occur as a consequence of degenerative processes, alterations in bone density and changes in vertebral architecture. The relationship between demographic characteristics and vertebral dimensions is important in radiological anatomy because measurements obtained from a heterogeneous adult population may demonstrate considerable variation. Nkwerem et al. (2024), for example, identified significant correlations between sex and several lumbar pedicle parameters in South-Eastern Nigerian adults. More broadly, recent comparative research has demonstrated that lumbar morphometric parameters vary according to vertebral level, population and individual characteristics (Nkwerem et al., 2024; Bonczar et al., 2025).

The clinical importance of lumbar vertebral morphometry extends beyond pedicle screw fixation to other spinal procedures, including decompression, interbody fusion, minimally invasive spinal surgery and procedures involving the neural foramina and spinal canal. Variations in the dimensions of the vertebral body, pedicles and spinal canal can affect the available surgical corridor and influence the risk of injury to neural and vascular structures. Recent evidence has emphasized that normative morphometric knowledge is valuable for accurate diagnosis, treatment planning and surgical intervention in spinal disorders. A 2025 systematic review and meta-analysis concluded that detailed knowledge of lumbar vertebral morphology can assist surgeons performing several forms of lumbar spinal surgery, including pedicle screw fixation and lumbar disc replacement (Bonczar et al., 2025).

The need for population-specific lumbar morphometric data is particularly important in the Nigerian setting. Although studies from other regions have provided extensive information on lumbar vertebral anatomy, differences in skeletal morphology between populations can limit the direct application of foreign measurements to Nigerian patients. Recent CT-based evidence from South-Eastern Nigeria has already demonstrated significant variation in lumbar pedicle measurements and their relationship with sex, while a 2026 study of West African adults further reported population-specific CT-derived lumbar morphometric indices and emphasized their potential value for clinical evaluation and surgical planning. A morphometric assessment of lumbar vertebrae using CT images at Imo State University Teaching Hospital (IMSUTH) can therefore provide additional regional data and contribute to the development of anatomical reference information that may be useful for radiologists, anatomists, orthopaedic surgeons, neurosurgeons and other professionals involved in spinal care (Nkwerem et al., 2024; Nwankwo et al., 2026).

1.2 Statement of the Problem

Lumbar spinal surgery increasingly depends on precise understanding of individual vertebral anatomy, particularly when instrumentation involves the pedicles. However, the dimensions and orientation of the lumbar vertebrae vary considerably between vertebral levels and individuals. Differences in pedicle width, height, length and angulation can influence the selection of screw size and trajectory, while inadequate knowledge of these parameters can increase the possibility of cortical breach, neurological injury, vascular injury, screw malposition and failure of spinal fixation. Despite the importance of these measurements, the classical description of lumbar vertebral anatomy does not adequately represent the full range of anatomical variation encountered in living patients (Li et al., 2023; Bonczar et al., 2025).

A further problem is that much of the available morphometric information has been generated from populations outside Africa, and measurements derived from one population may not necessarily be applicable to another. Studies have demonstrated significant differences in lumbar pedicle dimensions according to geographical and population groups, suggesting that implant selection and surgical planning based solely on foreign morphometric standards may not adequately reflect the anatomy of Nigerian patients. Although a recent CT study from South-Eastern Nigeria provided important information on lumbar pedicle dimensions, additional regional studies are necessary to establish a broader evidence base for Nigerian adults (Nkwerem et al., 2024; Li et al., 2023).

Another problem concerns the limited availability of comprehensive CT-based information covering multiple morphometric parameters of the lumbar vertebrae in Nigerian adults. Some existing investigations have concentrated primarily on pedicle dimensions, whereas other parameters, including vertebral body measurements, spinal canal dimensions, interpedicular relationships and other surgical landmarks, may also be important in operative planning. Recent international evidence shows that lumbar vertebral morphology involves multiple parameters that change systematically from L1 to L5. Consequently, assessment restricted to a single measurement may not provide sufficient anatomical information for comprehensive surgical application (Bonczar et al., 2025).

There is therefore a need for a CT-based morphometric study of the lumbar vertebrae among adults undergoing imaging at IMSUTH. Such a study can provide locally relevant measurements of important vertebral structures and examine variations according to vertebral level and selected demographic characteristics. The findings may help address gaps in regional anatomical data and provide useful reference information for preoperative planning, particularly for procedures involving pedicle screw fixation and other forms of lumbar spinal instrumentation. By generating CT-based morphometric data from the study population, the research can contribute to improved understanding of lumbar vertebral anatomy and its relevance to safe and effective spinal surgery (Nkwerem et al., 2024; Bonczar et al., 2025; Nwankwo et al., 2026).

1.3 Aim of the Study

The aim of this study is to perform a morphometric analysis of the lumbar vertebrae using computed tomography images and determine the relevance of the measured anatomical parameters to spinal surgery at Imo State University Teaching Hospital (IMSUTH).

1.4 Objectives of the Study

The specific objectives are to:

1. Determine the morphometric dimensions of the lumbar vertebrae (L1–L5) using CT images at IMSUTH, including selected vertebral body, spinal canal and pedicle measurements.
2. Assess the variations in pedicle dimensions and orientation across the lumbar vertebral levels from L1 to L5.
3. Determine the relationship between selected lumbar vertebral morphometric parameters and demographic characteristics, particularly age and sex, among the study population.
4. Evaluate the relevance of the identified lumbar vertebral morphometric characteristics to spinal surgical procedures, particularly pedicle screw fixation and other forms of lumbar spinal instrumentation.

1.5 Research Questions

The following research questions will guide the study:

1. What are the morphometric dimensions of the lumbar vertebrae (L1–L5) measured from CT images at IMSUTH?
2. How do pedicle dimensions and orientation vary across the lumbar vertebral levels?
3. What relationship exists between selected lumbar vertebral morphometric parameters and demographic characteristics, particularly age and sex?
4. What is the relevance of the identified lumbar vertebral morphometric characteristics to spinal surgical procedures, particularly pedicle screw fixation?

1.6 Research Hypothesis

Null Hypothesis (H₀): There is no statistically significant relationship between selected demographic characteristics and the morphometric dimensions of the lumbar vertebrae among adults assessed using CT images at IMSUTH.

1.7 Significance of the Study

The study will be significant to radiologists because it will provide quantitative information on the normal CT appearance and morphometric characteristics of the lumbar vertebrae in the study population. The measurements may serve as useful anatomical reference data when evaluating lumbar CT examinations and may improve understanding of normal variation in vertebral dimensions.

The study will also be significant to orthopaedic surgeons and neurosurgeons, particularly those involved in spinal instrumentation. Pedicle dimensions and orientation are critical considerations during pedicle screw placement. Knowledge of locally derived measurements may assist surgeons in selecting appropriate screw dimensions, determining trajectories and reducing the risk of pedicle cortical violation and associated complications (Nkwerem et al., 2024).

The study will benefit anatomists and medical educators by providing quantitative information that can supplement traditional descriptions of lumbar vertebral anatomy. CT-derived measurements can demonstrate how vertebral dimensions change from L1 to L5 and illustrate anatomical differences that may not be adequately represented by textbook descriptions.

The findings may also be useful to medical implant designers and biomedical researchers. Population-specific morphometric information can contribute to the design and selection of spinal implants that are appropriate for the anatomical characteristics of the intended patient population. The importance of such information is supported by evidence demonstrating considerable variation in pedicle dimensions between populations and vertebral levels (Li et al., 2023).

Furthermore, the study will contribute to Nigerian and West African anatomical literature by providing additional CT-based data on lumbar vertebral morphology. Existing Nigerian studies have demonstrated the importance of population-specific measurements, and additional datasets from different geographical regions can help establish a more comprehensive understanding of lumbar spinal anatomy in Nigerian adults (Nkwerem et al., 2024; Nwankwo et al., 2026).

Finally, the study may provide a basis for future clinical and anatomical research. The findings can be compared with studies from other Nigerian, African and international populations and may support subsequent investigations into spinal degeneration, vertebral anomalies, osteoporosis, spinal stenosis, surgical outcomes and implant design.

1.8 Scope of the Study

The study will focus on the morphometric assessment of the lumbar vertebrae from L1 to L5 using computed tomography images of adults at Imo State University Teaching Hospital (IMSUTH).

The study will assess selected anatomical parameters of the lumbar vertebrae, particularly measurements relevant to spinal surgery. These may include vertebral body dimensions, spinal canal dimensions, pedicle width and height, pedicle length, pedicle angulation and other appropriate measurements obtainable from the available CT images.

The study will also examine variations in the measurements according to vertebral level, age and sex, where appropriate demographic information is available. Particular emphasis will be placed on parameters relevant to pedicle screw fixation and other lumbar spinal procedures.

The study will not attempt to assess all possible anatomical characteristics of the lumbar spine or all clinical conditions affecting the lumbar vertebrae. It will specifically concentrate on measurable osseous characteristics obtainable from CT imaging and their relevance to spinal surgery.

1.9 Operational Definition of Terms

Morphometry: The quantitative measurement and statistical analysis of anatomical structures.

Lumbar Vertebrae: The five vertebrae forming the lumbar region of the vertebral column, designated L1 to L5.

Lumbar Spine: The portion of the vertebral column comprising the five lumbar vertebrae and their associated anatomical structures.

Computed Tomography (CT): A medical imaging technique that uses X-rays and computer processing to produce cross-sectional images of anatomical structures.

CT-Based Study: An anatomical investigation in which measurements are obtained from computed tomography images.

Pedicle: A short, strong bony structure connecting the vertebral body to the posterior elements of a vertebra.

Pedicle Width: The transverse distance between the medial and lateral cortical boundaries of the pedicle at its narrowest or clinically relevant point.

Pedicle Height: The superior-inferior dimension of the pedicle at the clinically relevant measurement level.

Pedicle Length: The length of the osseous pathway available for screw purchase, usually measured along the pedicular axis.

Pedicle Angulation: The angle formed by the axis of the pedicle relative to a defined anatomical reference plane.

Vertebral Body: The large anterior portion of a vertebra that primarily bears axial loads.

Spinal Canal: The canal formed by the vertebral foramina through which the spinal cord and associated neural structures pass.

Interpedicular Distance: The distance between corresponding pedicles on opposite sides of a vertebra.

Transpedicular Fixation: A spinal surgical technique in which screws are inserted through the vertebral pedicles into the vertebral body to provide spinal stabilization.

Pedicle Screw: A surgical implant inserted through the vertebral pedicle for spinal stabilization and fixation.

Spinal Surgery: Surgical procedures performed to treat disorders, injuries or structural abnormalities of the vertebral column and its associated neural structures.

Anatomical Variation: A difference in the size, shape, orientation or configuration of an anatomical structure between individuals or anatomical levels.

Surgical Relevance: The practical importance of an anatomical measurement or variation for planning, performing or improving the safety of a surgical procedure.

Project – Morphometric Analysis of the Lumbar Vertebrae and Its Relevance to Spinal Surgery: A CT-Based Study at IMSUTH