patella - The Lyon contribution to patellofemoral surgery part 1: from Albert Trillat to Henri Dejour
Background: Patellofemoral instability and pain have historically been managed with varied surgical techniques, often lacking a standardized diagnostic framework. The Lyon School of Knee Surgery has contributed significantly to the understanding of these pathologies over seven decades, transitioning from empirical procedures to a systematic, anatomy-based analytical approach.
Objective: This article reviews the chronological evolution of patellofemoral surgery in Lyon, detailing the development of diagnostic indices, the classification of instability, and the refinement of surgical interventions based on specific morphological abnormalities.
Key Points: Early management focused on distal realignment via medial transfer of the anterior tibial tubercle, notably the Elmslie-Trillat procedure. The introduction of the Caton-Deschamps index provided a reliable measure for patellar height. In 1987, a landmark classification distinguished objective patellar instability from patellofemoral pain syndrome. Four primary factors for instability were identified: trochlear dysplasia, present in 96% of cases, patella alta, an increased tibial tuberosity-trochlear groove distance, and excessive patellar tilt. Trochlear dysplasia is characterized on lateral radiographs by the crossing sign, supratrochlear spur, and reduced trochlear depth. These findings led to the "à la carte" surgical strategy, which addresses specific anatomical deficits, including the development of deepening trochleoplasty to correct high-grade dysplasia. Secondary factors such as femoral anteversion and genu valgum also influence patellar tracking but are less frequently corrected.
Conclusion: The Lyon School’s systematic methodology established a rigorous framework for diagnosing and treating patellofemoral disorders. By identifying specific morphological triggers for instability, surgeons can implement targeted procedures, moving beyond palliative realignment toward anatomical restoration of the extensor mechanism.
