Patellar Instability: A Narrative Review with an Integrated Treatment Algorithm

Patellar instability is a multifactorial condition characterized by episodic dislocation or subluxation of the patella, often affecting young and athletic populations. Patients present with patellar apprehension, swelling, and fear of having another episode. It results from a complex interplay between anatomical abnormalities, soft tissue dysfunction, and biomechanical imbalances.

This narrative review aims to provide a structured, up-to-date synthesis of the current understanding of patellar instability, from pathoanatomy and diagnostic evaluation to non-operative and operative management strategies, including specific considerations in skeletally immature patients.

A comprehensive literature review was conducted across major orthopedic databases and reference texts, focusing on key anatomical risk factors, diagnostic modalities, classification systems, and evidence-based treatment algorithms. Emphasis was placed on integrating recent findings with classical concepts such as Dejour's classification and the role of medial patellofemoral ligament reconstruction.

The management of patellar instability requires accurate identification of contributing factors such as trochlear dysplasia, elevated TT-TG distance, patella alta, and patellar tilt. First-time dislocators without predisposing factors may benefit from conservative management, while recurrent or anatomically predisposed cases often require individualized surgical correction. Procedures such as MPFL reconstruction, tibial tubercle osteotomy, and trochleoplasty have shown favorable outcomes when tailored to the patient's anatomy. In skeletally immature individuals, physeal-sparing techniques and guided growth are preferred to avoid iatrogenic growth disturbances.

A patient-specific, "à la carte" surgical approach grounded in detailed radiographic and clinical assessment yields the best outcomes in patellar instability. Integration of anatomical, biomechanical, and developmental considerations is essential for optimal treatment selection and long-term patellofemoral joint preservation.