JOSS ORIGINAL ARTICLE INTRODUCTION ABSTRACT

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1 ORIGINAL ARTICLE Anthropometric Study /jp-journals of Cervical Spine in Adult Nepalese 1 Pankaj R Nepal, 2 Suman Rijal, 3 Janam Shrestha, 4 Upendra P Devkota ABSTRACT Introduction: Anterior cervical discectomy with fusion (ACDF) and cervical corpectomies are commonly performed procedures in the neurosurgery and orthopedic units across the world. The size of the graft or prosthesis used is variable on individual basis. Also, geographical variations seem to play one of the vital roles in determining the size of the cervical vertebral body and intervertebral disk dimensions. Objective: To study dimension of C3 to C7 vertebral body and C2/3 to C7/T1 intervertebral disk. Inclusion criteria: Nepalese nationality aged between 18 to 60 year old and those with normal cervical spine Magnetic resonance imaging. Exclusion criteria: Traumatic cervical spine and any pathological lesion, such as infection/tumor, destructing the normal morphology of cervical vertebra. Study design: Cross-sectional study. Sample size: Fifty-two cases. Sampling technique: Nonprobability consecutive sampling. Duration: Retrospective 1 year. Results and conclusion: There were a total of 52 patients, 33 female and 19 male. With increasing age of C5 to C7, anterior-posterior (AP) diameter increases significantly. No significant association in different gender was noted. However, vertical height was smaller and AP diameter was in-between the study done at Israel and the US. Thus, there seems to exist geographical variation in the dimension of the cervical spine and may possess a greater clinical impact. The dimensions of the cervical spine may need to be considered while designing the prosthesis used in ACDF for Nepalese population. Keywords: Anthropometry, Cervical spine, Dimensions, Intervertebral disk, Measurement, Vertebral body. How to cite this article: Nepal PR, Rijal S, Shrestha J, Devkota UP. Anthropometric Study of Cervical Spine in Adult Nepalese. J Spinal Surg 2017;4(2): Source of support: Nil Conflict of interest: None INTRODUCTION Measurement of the various dimensions of the cervical, thoracic, and lumbar vertebrae were carried out in the past, where most of the researches were oriented towards the function of lamina, weight transmission, and morphology of pedicle Anterior cervical discectomy with fusion (ACDF) and cervical corpectomies are commonly performed procedures in the neurosurgery and orthopedic units throughout the world. The size of the graft or prosthesis used is variable on individual basis. Also, geographical variations seem to play one of the vital roles in determining the size of the cervical vertebral body and intervertebral disk dimensions Because of the geographic variation in the anthropometry of different population, this study was designed to determine the dimensions of C3 to C7 vertebral body and C2/3 to C7/T1 intervertebral disk in the Nepalese population. materials and methods This is a cross-sectional study done with a nonprobability consecutive sampling at a tertiary care center in Nepal, over duration of 1 year. All the cases included were Nepalese citizens aged between 18 to 60 years, who underwent cervical spine magnetic resonance imaging for various indications but reported to be normal. All the traumatic cases and pathological lesions, such as infection, tumor were excluded from the study. The variables measured in this study were age, gender, anterior-posterior (AP) diameter (Fig. 1), lateral diameter 1,2,4 Consultant, 3 Medical Officer 1-4 Department of Neurosurgery, National Institute of Neurological and Allied Sciences, Kathmandu, Bagmati, Nepal Corresponding Author: Pankaj R Nepal, Consultant Department of Neurosurgery, National Institute of Neurological and Allied Sciences, Kathmandu, Bagmati, Nepal, Phone: , drprnepal@yahoo.com Fig. 1: Anterior-posterior diameter of C3 to C7 vertebral body The Journal of Spinal Surgery, April-June 2017;4(2):

2 Pankaj R Nepal et al Fig. 2: Lateral diameter of cervical vertebral body (Fig. 2), height (Fig. 3) of C3 to C7 vertebral body, and the intervertebral disk height (Fig. 4) of C2/3 to C7/T1. To confirm the normal distribution of the variables; first of all, the normality testing of all the variables were done. Normality testing was done in three steps. Skewness and Kurtosis value obtained with Z-value between to in all the variables measured, followed by Shapiro- Wilk test where null hypothesis was kept as data to be normally distributed and was not rejected with p-value >0.05 in all tested variables. The graphical confirmation of the variables was done using histogram, Q-Q plot, and box plot, where all the variables were normally distributed. Predictive interval or the reference value was obtained using the formula 95% PI = mean ± t 0.975,n-1 (n + 1/n) SD DATA ANALYSIS Data analysis was done using the Statistical Package for the Social Sciences 20 version. Mean and standard deviation was calculated for the age, whereas mean, standard deviation, and predictive interval were calculated for the AP, lateral, and height of the vertebral body of C3 to C7, along with height of the intervertebral disk of the C2/3 to C7/T1 level. Two-tailed Pearson correlation of these dimensions was done with the age and the means were compared between different genders. The p-value <0.05 was considered significant. RESULTS Fig. 3: Vertical height of C3 to C7 vertebral body There were a total of 52 cases, with 63% male and 37% female (Graph 1). Mean age of the sample was (standard deviation 12.29) years. The mean with predictive interval of various dimensions of cervical spine are tabulated in Table 1; similarly, its correlation with age and gender in Table 2 and Table 3 respectively. Though females had smaller size vertebral bodies and disc dimensions of their respected levels, but the value is not significance (Table 3). However, the AP diameter of C5, C6 and C7 seems to be significantly correlated (Table 2) and showed increasing AP diameter with increasing age (Graph 2) DISCUSSION The ACDF is a commonly performed procedure in neurosurgery and orthopedic units throughout the world. Various methods to maintain the disk height after ACDF 56 Fig. 4: Intervertebral disk height of C2/3 to C7/T1 Graph 1: Gender distribution

3 Table 1: Mean with predictive interval of various dimensions of cervical spine Mean Standard deviation t 0.975,n-1 (n +1/n) SD Lower range (mm) Upper range (mm) C3 AP C4 AP C5 AP C6 AP C7 AP C3 lateral C4 lateral C5 lateral C6 lateral C7 lateral C3 vertical C4 vertical C5 vertical C6 vertical C7 vertical C2/C C3/C C4/C C5/C C6/C C7/T ; *P value < 0.05; ** is P value < 0.01 Table 3: Comparing means of dimensions between genders Vertebra Female Male p-value C3 AP C4 AP C5 AP C6 AP C7 AP C3 lateral C4 lateral C5 lateral C6 lateral C7 lateral C3 vertical C4 vertical C5 vertical C6 vertical C7 vertical C2/C C3/C C4/C C5/C C6/C C7/T have been described including autologus bone graft and instrumentation (viz. cage). Standard AP diameter of the cage used during ACDF ranges from 12 to 16 mm. 16 In this study, the mean AP of Table 2: Correlation of age with different dimensions of cervical spine Vertebra Pearson correlation value Sig (two tailed) C3 AP C4 AP C5 AP * C6 AP ** C7 AP ** C3 lateral C4 lateral C5 lateral C6 lateral C7 lateral C3 vertical C4 vertical C5 vertical C6 vertical C7 vertical C2/C C3/C C4/C C5/C C6/C C7/T C3 to C7 ranged 14.5 to mm, and the lower range is as small as mm (Table 1). Therefore, the required AP diameter of the cage for our population is slightly smaller. The standard lateral width of cage used are 12 to 20 mm in diameter, 16 and this size seems to be appropriate while using grafts or cage even in the Nepalese population. However, slight larger lateral diameter does not seem to be inappropriate, as mean lateral width in Nepalese population is mm in C3 to in C7 level (Table 1). The mean height of the intervertebral disk in Nepalese population is around 6 mm (Table 1), however, the height of the cage used in ACDF is 10 to 15 mm which is obviously larger. 17 Using cage of this height in our population causes cord traction. Therefore, appropriate height of cage needs to be considered during ACDF for Nepalese patients. The dimensions of the cervical vertebral body also seem to be different when compared with the other international studies. The vertical height of C3 to C7 vertebral body seems to be smaller compared with the study done at Israel 15 and the US population 13 (Table 4). The AP diameter of the Nepalese C3 to C7 vertebral body seems larger compared with the US population (Table 5). In contrast, the AP diameter is smaller when compared with Israeli and Mexican population. 12,15 However, the lateral dimension is larger than that of Mexican population (Table 6). 12 These changes could be attributed to the geographical variation of people living in the different parts of world. The Journal of Spinal Surgery, April-June 2017;4(2):

4 Pankaj R Nepal et al A B C Graphs 2A to C: Scattered diagram of correlation of C5-7 AP with age Table 4: Comparison of vertical height of C3 to C7 vertebral body with other study Israel US (male/female) Nepal C3 vertical C4 vertical C5 vertical C6 vertical C7 vertical Table 5: Comparison of AP diameter of C3 to C7 vertebral body with other study Israel Mexico Nepal (male/female) C3 AP C4 AP C5 AP C6 AP C7 AP Table 6: Comparison of lateral dimension of C3 to C7 vertebral body with other study Nepal Mexico C3 lateral C4 lateral C5 lateral C6 lateral C7 lateral CONCLUSION There seems to exist geographical variation in the dimension of the cervical spine and may possess a greater clinical impact. The dimensions of the cervical spine may need to be considered while designing the prosthesis used in ACDF for Nepalese population. REFERENCES 1. Abuzayed B, Tutunculer B, Kucukyuruk B, Tuzgen S. Anatomic basis of anterior and posterior instrumentation of the spine: morphometric study. Surg Radiol Anat 2010 Jan;32(1): Kayalioglu G, Erturk M, Varol T, Cezayirli E. Morphometry of the cervical vertebral pedicles as a guide for transpedicular screw fixation. Neurol. Med Chir (Tokyo) 2007 Mar;47(3): ; discussion Pal GP, Routal RV. A study of weight transmision through the cervical and upper thoracic regions of the vertebral columna in man. J Anat 1986 Oct;148: Olsewski JM, Simmons EH, Kallen FC, Mendel FC, Severin CM, Berens DL. Morphometry of lumbar spine: anatomical perspectives related to transpedicular fixation. J Bone Joint Surg Am 1990 Apr;72(4): Hou S, Hu R, Shi Y. Pedicle morphology of the lower thoracic and lumbar spine in a Chinese population. Spine (Phila Pa 1976) 1993 Oct 1;18(13): Ebraheim NA, Rollins JR, Xu R, Yeasting RA. Projection of the lumbar pedicle and its morphometric analysis. Spine (Phila Pa 1976) 1996 Jun 1;21(11): Pal GP, Routal RV. The role of the vertebral laminae in the stability of the cervical spine. J Anat 1996 Apr;188(Pt 2): Christodoulou AG, Apostolou T, Ploumis A, Terzidis I, Hantzokos I, Pournaras J. Pedicle dimensions of the thoracic and lumbar vertebrae in the Greek population. Clin Anat 2005 Sep;18(6): Liau KM, Yusof MI, Abdullah MS, Abdulla S, Yusof AH. Computed tomographic morphometry of thoracic pedicles: safety margin of transpedicular screw fixation in malaysian malay population. Spine (Phila Pa 1976) 2006 Jul 15;31(16):E45-E Ebraheim NA, Patil V, Liu J, Haman SP, Yeasting RA. Morphometric analyses of the cervical superior facets and implications for facet dislocation. Int Orthop 2008 Feb;32(1): Urrutia-Vega E, Elizondo-Omaña RE, De la Garza Castro O, Guzman López S. Morphometry of pedicle and vertebral body in a Mexican population by CT and fluroscopy. Int J Morphol 2009;27(4):

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