Patellar Instability Current Concepts and Controversies.

Recurrent patellar instability can significantly impact patients' quality of life and function. A large amount of research on patellar instability has been conducted in the past two decades, and a number of traditionally held principles of treatment have been challenged. This review addresses three current concepts and controversies in the treatment of patellar instability, specifically what factors lead to an increased tibial tubercle-trochlear groove distance and how to address them, when to add a tibial tubercle osteotomy to a medial patellofemoral ligament (MPFL) reconstruction, and which medial patellar stabilizers should be reconstructed. Based on current evidence, there are a few recommendations that can be made at this time. While trochleoplasty does have concerns with regard to reproducibility and complication risk, surgeons should consider this technique especially in cases with Dejour D trochlear dysplasia given high failure rates with other techniques. When evaluating whether to concomitantly perform a tibial tubercle osteotomy (TTO) with a MPFL, a TTO does appear to improve outcomes in the presence of maltracking or a positive J sign even with a tibial tuberosity-trochlear grove distance (TT-TG) of 18 to 20 mm, whereas patients without maltracking with a TT-TG of up to 25 mm may do well with an isolated MPFL reconstruction. Lastly, while MPFL reconstruction continues to have the most robust data supporting favorable outcomes, a number of biomechanical studies and short-term clinical studies have suggested promising results with medial quadriceps tendon femoral ligament and hybrid techniques.