ABSTRACT
Traditionally, the angle between the intersecting central axes (lateral projection intersecting central axes - LCA) of the proximal and distal fragments of metacarpal fractures is measured on radiographs. We recommend using the angle between the intersecting dorsal tangent lines instead (lateral projection intersecting dorsal tangent lines - LDT). We analyzed radiographs of 25 fractures of the fifth metacarpal bone shaft in three planes. Intraclass correlation coefficients (ICC) were used to estimate inter-rater and intra-rater reliability. Mean palmar tilt was 35.6° ± 12.5° according to LCA and 27.6° ± 12.0° according to LDT. There were no differences during repeated measurements. Intra-rater reliability was high: ICC (95% CI) for LDT was 0.82 (0.74-0.88) and for LCA it was 0.71 (0.51-0.83). Mean values of palmar tilt using LCA exceeded those using LDT by 8.0° ± 7.7° (p < 0.001). Only LDT measurements provided comparable results between all raters. In conclusion, we demonstrated the feasibility and reliability of intersecting dorsal tangent lines for measuring palmar tilt in fifth metacarpal fractures as an alternative to the commonly used angle between the intersecting central axes.
