No clinically relevant relationship between different quantitative measurement methods of the lateral femoral condyle morphology on lateral radiographs in anterior cruciate ligament-injured patients.

PURPOSE: To clarify whether different methods of quantifying lateral femoral condyle (LFC) bone morphology as risk factors for anterior cruciate ligament (ACL) injury on lateral radiographs should be considered as individual risk factors and to assess inter- and intraobserver reliability.

METHODS

We retrospectively reviewed 487 patients undergoing primary ACL reconstruction at our institution. Routine lateral radiographs of the injured knees were utilized to measure the following parameters: LFC ratio (LFCR), height of LFC to anteroposterior diameter ratio (HAPR), femur tibia size ratio (FTSR), tibia to posterior femoral condyle ratio (TPFCR) and Porto ratios (XY/AB; B/AB; B/XY). Malrotated radiographs were excluded. Pearson's correlation coefficients were used to identify relationships. Intraclass correlation coefficients were calculated for inter- and intraobserver reliability for two raters.

RESULTS

Fifty-eight patients were included. Means and standard deviations for LFCR were 63.7% ± 2.8%, HAPR 0.35 ± 0.02, FTSR 1.23 ± 0.07, TPFCR 2.99 ± 0.28, XY/AB 0.41 ± 0.08, B/AB 1.20 ± 0.06 and B/XY 3.05 ± 0.58. Significant correlations were observed between FTSR and XY/AB (r = 0.425), B/AB (r = 0.582) and TPFCR (r = -0.326), between XY/AB and HAPR (r = -0.309) and B/XY (r = -0.933) and between TPFCR and B/AB (r = 0.302). Intraobserver agreement was excellent for LFCR, HAPR, FTSR, TPFCR and B/AB and good for XY/AB and B/XY. Interobserver agreement varied from poor for XY/AB and B/XY, good for HAPR, B/AB, FTSR and TPFCR to excellent for LFCR.

CONCLUSION

Different methods of quantifying LFC bone morphology should be considered as individual risk factors, characterized by good to excellent intraobserver reliability, but highly variable interobserver reliability.

LEVEL OF EVIDENCE: Level III.