Jordy van Sambeeck

Patellar height measurements: Insall-Salvati ratio is most reliable method 2 35 Results Of the 48 patients, 11 were male and 37 were female. Median age was 22 (18-51) years. The radiographs and scans were of variable quality because some of these patients were referrals from other hospitals where imaging had already been performed. However, none of the scans needed to be rejected due to poor quality. Table 1 shows the minimum and maximum ICC values for intra-observer reliability of each measurement. The IS was the only measurement that had a moderate to good or excellent intra- observer reliability on CR (0.72 – 0.91), CT (0.78 – 0.83) and MRI (0.70 – 0.85). The intra-observer reliability of the PTI for MRI was good to excellent for all observers (0.81 – 0.91). The lowest intra-observer reliability was seen with the other MRI measurements (BP 0.42 – 0.73, CD 0.26 – 0.84, MIS 0.18 – 0.76). Of all observers the radiologist scored the best overall intra-observer reliability. The overall ICC’s of the medical student however were clearly lower than those of the other three observers. To include these measurements in the calculation of inter-observer reliability would significantly alter and cloud the final inter-observer reliability results. For this reason, and because in every day practice these measurements are not done by students, the results of the medical student were excluded from calculating the ICC’s for inter-observer reliability. CR CT MRI IS 0.72 (0.56 - 0.83) 0.91 (0.83 - 0.95) 0.78 (0.65 - 0.87) 0.83 (0.72 - 0.90) 0.70 (0.53 - 0.82) 0.85 (0.60 - 0.93) BP 0.63 (0.42 - 0.77) 0.80 (0.67 - 0.89) 0.38 (-0.07 - 0.67) 0.84 (0.73 - 0.90) 0.42 (-0.24 - 0.32) 0.73 (0.33 - 0.88) CD 0.71 (0.54 - 0.83) 0.84 (0.67 - 0.91) 0.67 (0.49 - 0.80) 0.83 (0.71 - 0.90) 0.26 (0.00 - 0.49) 0.84 (0.64 - 0.92) MIS 0.48 (0.07 - 0.72) 0.73 (0.56 - 0.83) 0.48 (0.21 - 0.67) 0.85 (0.74 - 0.91) 0.18 (-0.10 - 0.44) 0.76 (0.57 - 0.87) PTI -- -- 0.81 (0.70 - 0.89) 0.91 (0.84 - 0.95) Table 1. Intra-observer reliability: ICC min/max values (CI 95%) Table 2 shows the ICC’s for inter-observer reliability of each measurement. The inter-observer reliability was good for IS measurements on CR (0.80), CT (0.75) and MRI (0.78). The overall ICC was moderate to good for CR and CT. The PTI showed good inter-observer reliability (0.80), however ICC for BP, CD and MIS was poor on MRI (0.09, 0.41 and 0.27 resp.).