Management of the chronically dislocated patella during total knee arthroplasty

The chronically dislocated patella is usually associated with fixed valgus and often with fixed-flexion deformities. All components of the deformity must be addressed to achieve a satisfactory result following total knee arthroplasty. The proper rotation of the tibial and femoral components is critical, and slight external rotation of either component will assist patellar tracking. Extensor mechanism realignment is performed proximally, usually with the “tube” realignment technique or occasionally with a Coonse-Adams extensor turndown technique. Distal extensor realignment is discouraged. Cemented implants are preferable; metal-backed patellar components should be avoided. Postoperative rehabilitation is modified to protect the extensor mechanism repair.