Anatomic Risk Factors for Lateral Patellar Instability.

Area of Science:

• Orthopedics
• Biomechanics
• Radiology

Background:

• Patellar instability is a common orthopedic condition affecting approximately 42 per 100,000 individuals annually.
• It results from impaired patellar tracking, potentially leading to cartilage damage and dysfunction.
• The stability of the patellofemoral (PF) joint depends on a complex interplay of muscular forces, soft tissues, joint geometry, and limb alignment.

Purpose of the Study:

• To review and define the various anatomical patellar risk factors (APRFs) associated with patellar instability.
• To highlight the biomechanical and clinical significance of APRFs in the context of patellar instability.
• To discuss current evaluation methods and identify gaps in clinical data for guiding treatment decisions.

Main Methods:

• Review of identified anatomical patellar risk factors (APRFs) including patella alta, rotational malalignment, genu valgum, lateralized tibial tubercle, and trochlear dysplasia.
• Discussion of biomechanical consequences of APRFs, such as increased lateralizing forces and maltracking.
• Overview of current diagnostic imaging modalities for APRF evaluation, including radiography, MRI, and CT scans.

Main Results:

• Over 80% of patients with patellar instability exhibit at least one APRF.
• APRFs biomechanically increase lateral patellar forces, maltracking, and PF joint pressure, while decreasing contact area.
• APRFs are clinically associated with higher recurrence rates after initial instability episodes and lower success rates for medial PF ligament reconstruction.

Conclusions:

• Anatomical patellar risk factors are significantly associated with patellar instability and influence treatment outcomes.
• While individual APRFs can be assessed, robust data is lacking to guide treatment thresholds and surgical management decisions.
• Comprehensive evaluation of APRFs is a fundamental component of managing patellofemoral instability.