Assessment of Static Pelvic Parameters According to Ethnicity: Cohort Analysis of 500 Computed Tomography Scans

Pelvic incidence (PI) is often used to predict ideal lumbar lordosis in an individual. To date, no study has considered the potential influence of Māori ethnicity (Māori are the indigenous people of New Zealand). Identifying variation in key surgical measurements may aid in reducing health care inequities. The aim of this study was to compare static pelvic parameters according to ethnicity from a New Zealand cohort.

A total of 500 computed tomography scans obtained for major trauma assessment were analyzed, and static pelvic parameters were measured, including PI, pelvisacral angle, femorosacral pelvic angle, sacropelvic angle, sacral table angle, sacral anatomic orientation, pelvic thickness, and L5 segmental angle. Analysis was performed comparing age, gender, and ethnicity cohorts.

The mean age of the entire cohort was 42.6 years (SD 18.7). There were 323 men (65%). Only the L5 segmental lordosis differed significantly between the genders. Among the cohort, 287 indicated they were New Zealand European (NZE), 159 Māori, 20 Pacifica, and 34 "Other." Age differences were present between the predominant ethnic groups NZE and Māori (6.95 years; P < 0.001). Significant differences were also seen between these 2 groups for PI (Māori 3° greater), pelvisacral angle, pelvic thickness, sacropelvic angle, sacral table angle, and L5 segmental angle (Māori 1.2° less).

In this first large-scale analysis from New Zealand including Māori, significant differences in a majority of parameters are evident. This reflects significant variation in pelvic morphology and possible differences in normal spinal alignment that should now be a focus of future studies.

Pelvic morphology in Māori differs from that of non-Māori. Efforts are needed to establish normative values in Māori and thus reduce health care inequities.