AGREEMENT BETWEEN MRI KNEE AND PLAIN RADIO GRAPHIC FINDINGS FOR TROCHLEAR DYSPLASIA AT TERTIARY HOSPITAL

Abstract

Objectives
The objective of this study was to determine the level of agreement between Magnetic Resonance Imaging (MRI) of the knee and plain radiographic findings in the diagnosis of trochlear dysplasia in patients presenting with knee pain or suspected patellofemoral instability.

Methodology
A cross-sectional study was conducted at a tertiary care hospital, in Rawalpindi. A total of 120 patients who presented with knee pain, recurrent patellar instability, or suspected patellofemoral joint abnormalities and underwent both knee MRI and plain radiography were included in the study. Data were collected from radiology department records after obtaining ethical approval. Plain radiographs (lateral and axial views) and MRI scans were reviewed by experienced radiologists to identify features suggestive of trochlear dysplasia. Radiographic signs included the crossing sign, supratrochlear spur, and shallow trochlear groove, while MRI was used to assess trochlear morphology in detail. Qualitative variables included gender and the presence or absence of trochlear dysplasia on MRI and radiography, while quantitative variables included patient age. Data were analyzed using statistical software. Frequencies and percentages were calculated for qualitative variables, and mean ± standard deviation was calculated for quantitative variables. Agreement between MRI and radiographic findings was assessed using Cohen’s kappa coefficient, with p ≤ 0.05 considered statistically significant.

Results
The mean age of the patients was 32.6 ± 9.8 years (range 18–55 years). Among the participants, 70 (58.3%) were male and 50 (41.7%) were female. Trochlear dysplasia was detected in 46 patients (38.3%) on MRI and 39 patients (32.5%) on plain radiography. Concordant positive findings were observed in 34 patients, while 69 patients were negative on both modalities. Twelve patients showed dysplasia on MRI but not on radiography, whereas 5 patients were positive on radiography but negative on MRI. Cohen’s kappa analysis demonstrated moderate agreement (κ = 0.58) with a statistically significant p-value (<0.001).

Conclusion
MRI and plain radiography showed a moderate but significant agreement in the diagnosis of trochlear dysplasia. However, MRI demonstrated higher sensitivity and detected additional cases not visible on radiographs. Therefore, MRI should be considered a valuable complementary imaging modality for accurate assessment of trochlear dysplasia in patients with patellofemoral instability.