Table 1.

Classification of procedure codes and explanations of the procedures in each class

Procedure codes	Includes
Ligament reconstruction or repair
NGE60; NGE65	MPFL or MPTL reconstruction or repair
Extensor realignment
NGL66; NGL30; NGK99	Tibial tubercle transfer Patellar tendon shift Imbrication of vastus medialis
Trochleoplasty
NGG00	Trochleoplasty
Femoral osteotomies
NFK30	Varus-producing osteotomy of femur Torsional osteotomy of femur
Reimplantation of osteochondral fractures
NGF30; NGF35	Open or arthroscopic reimplantation of osteochondral fractures
Debridement
NGA30; NGD05; NGF00; NGF25	Arthroscopy Loose fragment removal Plica resection Menisci debridement
Capsular release
NGE10; NGE15	Lateral capsular release
Unspecified procedures
NGH20

The included procedure codes were used together with patellar dislocation diagnosis. Each included procedure code was used more than 100 times during the study period