• ABSTRACT
    • Numerous anatomic factors have been shown to contribute to patellar instability. Patellar height remains a critical, yet underappreciated contributor to instability that is amenable to surgical correction through the performance of a tibial tubercle distalization osteotomy (TTDO). The indications for a distalizing tibial tubercle osteotomy are not completely clear and depend on multiple factors. One must consider patient factors and physical examination findings in addition to radiographic measures. In general, the addition of a TTDO to medial patellofemoral ligament reconstruction should be considered when the degree of patella alta exceeds a Caton-Deschamps Index (CDI) of 1.4. The presence of trochlear dysplasia, patellar maltracking (J-sign), lateral patellar apprehension that persists at higher flexion angles, and decreased patellotrochlear articular cartilage contact on sagittal magnetic resonance imaging may drive the decision to proceed with distalization when the CDI is lower. Complications of distalization osteotomies are frequent and careful attention to surgical technique is critical to obtain good outcomes.