MRI as a Stand-Alone Tool Fails to Accurately Assess Medial Patellofemoral Ligament Integrity: A Radiographic Analysis.

Abstract

Background The medial patellofemoral ligament (MPFL) is of critical importance for patellar stability and is universally incompetent in patients with patella dislocations. However, radiologic (MRI) assessment of the MPFL's integrity following dislocation is variable, adding confusion to patients and providers during treatment decision-making. Hypothesis/Purpose We aimed to assess the reliability of MRI to evaluate MPFL integrity by measuring inter- and intra-observer agreement between a musculoskeletal radiologist and an orthopedic surgeon, specializing in sports medicine using a novel standardized MRI-based scoring system. We anticipated higher intra-observer than inter-observer reliability of MPFL integrity. Methods We retrospectively reviewed 100 consecutive knee MRIs: 50 from patients with a clinical history of recent acute patellofemoral dislocation and 50 controls drawn from an ACL-injury cohort who had no history or clinical symptoms of patellar instability. Two blinded reviewers, an orthopedic surgeon with fellowship training in sports medicine and subspecialty expertise in patellofemoral pathology, and a fellowship-trained musculoskeletal radiologist, independently evaluated the medial patellofemoral ligament (MPFL) on axial MRIs. Results Demographic characteristics (age, BMI, sex) did not differ significantly between the instability and control groups. Eight percent of patellar instability patients had their MPFL graded as "intact" in our first review. Twenty-six percent of ACL control patients had their MPFL graded as at least attenuated. Intra-observer reliability was substantial to excellent and inter-observer reliability was fair to moderate. Conclusion Our findings demonstrate that MRI-based evaluation of MPFL integrity lacks the consistency and accuracy required for confident clinical decision-making and that MRI findings do not universally correlate with clinical history. These findings support a growing consensus that current imaging analyses alone are insufficient for surgical decision-making in patellofemoral instability, particularly in the assessment of the MPFL.