Different Patellar Indices and Their Role in Decision-Making: An MRI-Based Study

Area of Science:

• Orthopedics
• Radiology
• Biomedical Engineering

Background:

• Knee MRI is crucial for evaluating patellofemoral pain.
• Surgical decisions for patellofemoral pain can benefit from standardized imaging metrics.
• Assessing normal patellar indices is key to understanding patellofemoral alignment.

Purpose of the Study:

• To establish normal ranges for patellar indices from knee MRI.
• To analyze correlations and agreements between different patellar indices.
• To compare these indices across diverse ethnic populations.

Main Methods:

• Prospective analysis of 117 knee MR images.
• Calculation of Insall-Salvati (IS), modified IS, patellotrochlear (PT), and patellophyseal (PP) indices.
• Statistical analysis including Cohen's kappa and Pearson's correlation.

Main Results:

• Mean values: IS=1.00, modified IS=1.53, PT=0.40, PP=0.58.
• Strong negative correlation and good agreement observed between PT and PP indices.
• 4% of asymptomatic patients fell outside standardized cut-off values, with varying classifications by different indices.

Conclusions:

• Patellar position is one of many factors in surgical decisions for patellofemoral pain.
• Existing patellar indices show limited correlation, except for PT and PP.
• Further research is needed to clarify the clinical utility of these indices in surgical planning.