Table 1. Tabulated risk factors for patellar instability.

Several bones, ligaments, and muscle abnormalities have been identified as risk factors for patellar instability. Trauma is another risk factor that can cause patellar instability directly or indirectly by affecting bones, ligaments, or muscles.

mpFL: medial patellofemoral ligament; TTTG: tibial tubercle-trochlear groove

Bones	Ligaments	Muscles	Trauma
Femoral torsion	mPFL	Weakness	Accident
Tibial torsion	Generalized laxity	Hypotonia	Habitual (no accident)
Valgus knee alignment		Hypertonia
Trochlear dysplasia
Patellar dysplasia
Patella alta
High TTTG