RELATIONSHIP OF THE BODY MASS INDEX (BMI) WITH THE LUMBAR RADIOLOGICAL FINDINGS IN THE INCIDENCES OF LOW BACK PAIN

Comparable relationship between BMI, lumbar radiological findings/diagnosis, and features of patients that presents with low back pain has been a research of interest in the diagnosis of low back pain.

Aim: To investigate the association between body weights, body mass index, age, features and clinical findings in patients with low back pain.

Patients and Method: A prospective study of 84 patients who presented for radiographic examination of the lumbar spine due to low back pain, at National Orthopaedic Hospital Enugu and Nnamdi Azikiwe University Teaching Hospital Nnewi, was conducted. Statistical package for social science (SPSS) version 17.0 was used to analyze the data, using Pearson correlation function.

Result: The frequency of females referred for the radiographic examination of the lumbar spine due to low back pain was significantly more than males (54.8% against 45.2%). The age group of 58 and below had the highest frequency of referral (76.2%). A higher frequency of referred patients had optimal body mass index (37; 44.2%). Highest frequency of referred patients has disc space narrowing (48.8%). For the concluded clinical diagnosis, the highest frequency of referred patients had spondylosis. There was positive correlation between BMI and osteopaenia (p=0.008, <0.05) and between BMI and osteophyte formation (p=0.009, <0.05). There was negative correlation between BMI and the concluded clinical diagnosis (p>0.05).

Conclusion: The result shows that females are referred for radiographic examination of the lumbar spine due to LBP than males. It also revealed that spondylosis was the predominant diagnosis made in most of the patients. It also showed that there is a significant association between BMI and radiographic features like osteopaenia, and BMI and osteophyte formation. But showed a negative association between BMI and the concluded clinical diagnosis made. The occupational contribution was also noted.

Keywords: BMI, Lumbar radiographic features, referral, clinical diagnosis, NOHE, NAUTH.

CHAPTER ONE

CHAPTER TWO

CHAPTER THREE

CHAPTER FOUR

CHAPTER FIVE

REFERENCES

APPENDIX

     BMI is defined as the individual’s mass divided by the square of their height.

BMI = (MASS(kg))/(HEIGHT(m2))

BMI for the ratio and its popularity is found to be the best proxy for body fat percentage among ratios of height and weight. [2][3] The interest in measuring body fat being due to obesity becoming a discernible issue.

     The current value settings are as follows;

 BMI of 18.5 to 25 may indicate optimal weight.

 BMI lower than 18.5 suggest underweight.

 BMI above 25 may indicate overweight.

 BMI above 30 suggest obese (over 40, morbidly obese).

Obesity and overweight are linked to more deaths worldwide than underweight. Raised BMI is a major risk factor for musculoskeletal disorders especially osteoarthritis, a highly disabling degenerative disease of the joints.[4] Being overweight or obese can significantly contribute to symptoms associated with osteoporosis, osteoarthritis, rheumatoid arthritis, degenerative disc disease, spinal stenosis, and spondylolisthesis.

     A number of mechanisms for the fat-bone relationship exist and include the effect of soft tissue mass on skeletal loading, the association of fat mass with the secretion of bone-active hormones from the pancreatic beta cells (including insulin, amylin, and preptin) and the secretion of bone-active hormone, (e.g. estrogens and leptin) from the adipocytes. [5] An understanding of this aspect of bone biology may open the way for new treatments of osteoporosis and low back pain.

     The lower back is an intricate structure of interconnected and overlapping elements;

 Tendons and muscles and other soft tissues.

 Highly sensitive nerves and nerve roots that travel from the lower back down into the leg and feet.

 Small and complex joints.

 Spinal discs with their gelatinous inner cores.

An irritation with any of these structures can cause lower back pain. [6]

     Low back pain or Lumbago is a common musculoskeletal disorder affecting 80% of people at some point in their lives [7], which can be caused by a wide range of factors such as inflammatory, mechanical, infectious, and psychological.  The majority of low back pain is referred to as non-specific low back pain and does not have a definitive cause. [8] It is believed to stem from benign musculoskeletal problems such as muscle or soft tissue sprains or strains.[9] It is the common condition which has been described as a serious health problem in many industrialized countries like Nigeria.[10] Low back pain causes severe disruption for the sufferer’s quality of life by limiting his/her professional and labour task.[11]

     Loading the spinal column causes the intervertebral discs to lose height by the radial bulging of the annulus fibrosus and by expelling fluid from the nucleus pulposus and annulus fibrosus. [12] The two mechanisms result in the decrease of the discs’ height and in a shortening of the spinal column (also called spinal shrinkage). Spinal shrinkage decreases its ability to absorb/transmit forces and causes increased or abnormal loading on the other structures of the spine, e.g. facet joints, spinal ligaments, and so on.[13] This is a contributory factor to the development of low back pain. [14]

          Therefore, one region of the spine that is most vulnerable to the effects of obesity is the lower back- the lumbar spine, causing an increased curvature of the low back, and other regions of the spine(neck) may become painful.

     The investigative management for LBP range from radiography, computed tomography (CT), magnetic resonance imaging (MRI), myelography, radionuclide imaging. Other more invasive methods include epidural venography, vertebroplasty, discography, laser disk decompression, percutaneous nerve root blocking, and percutaneous injection of the facet joints are used in some centers and are usually performed by radiologists.[15] Plain radiographs are routinely ordered in patients with mechanical and neurogenic pain of the lower back.

     A lumbosacral spine radiograph is a picture of the small bones (vertebrae) in the lower part of the spine, which includes the lumbar region and the sacrum, the area that connects the spine to the pelvis. It may show:

 Abnormal curves of the spine

 Abnormal wear on the cartilage and bones of the lower spine, such as bones spurs and narrowing of the joints between the vertebrae

 Cancer (although cancer often cannot be seen on this type of radiograph)

 Fractures

 Signs of thinning bones (osteoporosis)

 Spondylolisthesis, in which a bone (vertebra) in the lower part of the spine slips out of the proper position onto the bone below it.

     Modern neuroimaging techniques such as CT and MRI have improved the diagnosis and detection of the cause of LBP. These imaging modalities are not available in most communities, because they are quite expensive. As regards this, physicians tend to use radiography for the least initial assessment of LBP. It is therefore very important to evaluate patients that present with LBP critically, and access for possible relationship between the findings and the patients’ characteristics.