Osteoarthritis with permanent dislocation of the patella treated by total knee arthroplasty through a lateral approach: A report of two cases

INTRODUCTION: Permanent dislocation of the patella (PDP) is a rare condition. In cases of PDP with tibiofemoral arthritis, total knee arthroplasty may be performed through a medial parapatellar approach with patellar realignment. In this article we present two cases of PDP with tibiofemoral osteoarthritis successfully treated via lateral approach TKA without any additional realignment procedure. We performed two total knee arthroplasties for PDP with lateral tibiofemoral arthritis through a lateral approach without any realignment procedure. Mobile bearing inserts were used to adjust rotational alignment. The patients showed improved functional outcomes (Japanese Orthopaedic Association Knee score and Oxford Knee Score), and improved range of motion. Three years postoperatively, the patellae remain stable without dislocation nor maltracking, maintaining a high functional score. CONCLUSION: To treat permanent dislocation of the patella with lateral knee osteoarthritis, TKA through a lateral approach have potential to be a new treatment option to achieve both a good outcome and repositioning of the patella.