CT and MRI as Diagnostic and Management Decision Tools for First Time Lateral Patellar Dislocations: A...

Area of Science:

• Orthopedic Surgery
• Radiology
• Sports Medicine

Background:

• First-time lateral patellar dislocation (FTLPD) often leads to recurrent dislocations in 50% of patients.
• Conservative treatment is common, but surgical decision-making relies on imaging and clinical findings.
• Key surgical indications include intraarticular free bodies, medial patellofemoral ligament (MPFL) tears, and lateral patellar displacement.

Purpose of the Study:

• To evaluate the efficacy of different imaging modalities (radiographs, CT, MRI) in identifying surgical indications after lateral patellar dislocation.
• To compare the diagnostic yield of individual and combined imaging techniques for determining surgical necessity.
• To analyze FTLPD as a distinct subgroup.

Main Methods:

• Retrospective review of knee radiographs, MRI, and CT scans from 34 patients with lateral patellar dislocation (26 with FTLPD).
• Evaluation for intraarticular free bodies, fractures, ligament tears (MPFL), and patellar displacement (TT-TG distance).
• Comparison of surgical indication detection rates between imaging modalities and their combinations.

Main Results:

• CT and MRI detected significantly more intraarticular free bodies than radiographs in FTLPD patients.
• Combined MRI and CT findings indicated surgery for 21 of 26 FTLPD patients, exceeding individual modality detection rates.
• CT demonstrated superior performance over MRI alone or MRI with radiographs in identifying patients requiring surgery.

Conclusions:

• Advanced imaging, specifically MRI or CT, is crucial for determining surgical necessity after lateral patellar dislocation.
• Consider a second, different imaging study if the initial study or clinical presentation does not establish a clear surgical indication.
• Combined imaging approaches enhance the detection of surgical indications for recurrent patellar instability.