Ethnic variations of selected cervical spine radiographic parameters of females in KwaZulu-Natal

Aim: To evaluate the normal selected cervical spine radiographic parameters i.e. the cervical lordosis (CL), sagittal canal diameter (SCD), interpedicular distance (IPD) and cervical gravity line (CGL) in asymptomatic young to middle-aged females across four ethnic groups (Black, White, Indian and Coloured) in Durban, KwaZulu Natal, South Africa. Participants: Eighty apparently healthy females between the ages of 18 and 45 years from the Black, Indian, Coloured and White ethnic groups in Durban, KwaZulu Natal. Methodology: Written informed consent was obtained from each participant. A case history, physical examination and an orthopaedic assessment of the cervical spine was conducted for each participant. Study specific data such as ethnicity, age, height and weight was recorded. A lateral and an A-P radiograph of the cervical spine were taken for each participant. The selected radiographic parameters viz. cervical lordosis (CL), sagittal canal diameter (SCD), interpedicular distance (IPD) and cervical gravity line (CGL) were evaluated according to methods described previously. SPSS version 15.0 (SPSS Inc., Chicago, Illinois, USA) was used for data analysis. Coefficients of variation were calculated within ethnic groups to assess intra-group variation. Inter-group variation was assessed using ANOVA testing with Bonferroni-adjusted post-hoc tests in the case of a significant ANOVA test. Pearson’s chi square test was used to assess the association between ethnic groups and position of the CGL. T-tests were used to compare mean CL between those with anterior and normally placed CGL within each ethnic group. Results: The mean ± SD of the CL in South African females by ethnic group using the C1-C7 and C2- C7 methods CERVICAL LORDOSIS (mean ± SD) (°) ETHNICITY C1-C7 C2-C7 Black 42.1° (±13.4) 16.3° (±8.3) White 37.4° (±10.3) 9.9° (±4.8) Indian 33.7° (±9.7) 6.9° (±4.8) Coloured 42.5°(±10.9) 12.1° (±9.5) The mean ± SD of the SCD in South African females by ethnic group SAGITTAL CANAL DIAMETER (mean ±SD)(mm) ETHNICITY Black White Indian Coloured SCDC2 SCDC3 SCDC4 SCDC5 SCDC6 SCDC7 20.2 (±1.7) 17.4 (±1.4) 17.2 (±1.4) 17.0 (±1.4) 17.6 (±1.3) 17.5 (±1.4) 20.8 (± 2.2) 17.9 (±1.6) 17.6 (±1.6) 17.4 (±1.6) 17.6 (±1.4) 21.0 (±2.0) 18.2 (±1.7) 17.5 (±1.5) 17.4 (±1.7) 17.6 (±1.6) 17.1 (±1.5) 20.3 (±1.6) 17.5 (±1.8) 17.4 (±1.5) 17.7 (±1.2) 17.6 (±1.3) 16.9 (±1.2) 16.9 (±1.4) The mean ± SD of the IPD in South African females by ethnic group INTERPEDICULAR DISTANCE (mean ±SD)(mm) ETHNICITY IPDC3 IPDC4 IPDC5 IPDC6 IPDC7 Black 27.0 (±2.8) 27.6 (±3.2) 28.2 (±4.0) 28.9 (±4.2) 27.5 (±3.5) White 28.4 (±2.6) 28.8 (±2.2) 29.5 (±2.3) 29.3 (±2.5) 28.2 (±2.9) Indian 27.2 (±1.8) 27.5 (±1.8) 27.9 (±1.6) 27.9 (±1.6) 27.5 (±2.0) Coloured 27.9 (±2.3) 27.8 (±2.3) 28.3 (±2.2) 28.4 (±1.8) 28.2 (±1.7) The placement of the CGL in South African females in each ethnic group CERVICAL GRAVITY LINE ETHNICITY PLACEMENT OF CGL Black 70% anterior placement White 70% anterior placement Indian 60% anterior placement Coloured 60% anterior placement The C1-C7 measurements and the C2-C7 CL measurements were significantly different amongst the ethnic groups. For the C2-C7 method, Blacks differed significantly from both Whites (p = 0.037) and Indians (p = 0.001; Bonferroni adjusted post-hoc test); with the values for the Blacks being higher than both Whites and Indians. There was no correlation between CL and BMI amongst any of the selected ethnic groups. There were no significant differences in the mean SCD and IPD amongst the ethnic groups (p > 0.05; ANOVA test). There was no significant association between any ethnic group and the position of the CGL (p = 0.830; Pearson’s chi square test). In Black females, those with a normally positioned CGL had significantly higher C2-C7 CL measurements (p = 0.008; T- tests). There was no correlation between the CL and anterior placing of the CGL in any of the ethnic groups. Conclusion: No individual differences were observed in the CL amongst the ethnic groups when using the C1-C7 method. However, significant differences were observed when the C2-C7 method was used. There were no significant differences observed in the mean SCD and IPD amongst the ethnic groups. In Black females, those with a normally positioned CGL had significantly higher C2-C7 CL measurements. The trends observed in this research study and the differences in the findings to those of previous studies lay the platform for a larger population-based study across South Africa to establish normative reference values for each radiographic parameter specific for gender and ethnicity.