Measurement of Neck-Shaft Angle Using CT Scout View in Healthy Jordanian Adults - A Reliability and Agreement Study

Aims: To report estimates of the reliability and agreement of a new method for measuring the femoral Neck-shaft angle in the Jordanian population. The neck-shaft angle is an important anatomical indicator in orthopedics of the hip. While there are different approaches to measuring the neck-shaft angle in the literature, there is no agreement on the best technique used for measurement. CT scout view was used in this study to provide a promising alternative.

Study Design: Observational reliability and agreement study.

Places and Duration of the Study: Department of physiotherapy, school of rehabilitation science, University of Jordan and University of Jordan Hospital between March 2014 and October 2015.

Methodology: Two independent raters calculated the neck-shaft angle on each hip of 50 pelvic CT scout images of healthy adults to determine inter-rater reliability. One rater performed the measurement twice to determine the intra-rater reliability. Intra-class correlation coefficients were used to examine relative reliability. The standard error of measurement (SEM) and 95% minimal detectable change (MDC) were calculated to examine absolute reliability.

Results: The mean value of all angle measurements was 131.3. Intra-class correlation coefficients were 0.726 and 0.63 for inter and intra-rater measurements respectively. SEM and MDC for inter-rater measurements were 2.69 and 7.46 respectively. For intra-rater measurements, they were 2.84 and 7.86 respectively.

Conclusion: The new method proposed in this study for measuring the neck-shaft angle showed good reliability and small measurement error.