MANAGEMENT OF THE CHRONIC IRREDUCIBLE PATELLAR DISLOCATION IN TOTAL KNEE ARTHROPLASTY

Neglected dislocation of the patella with gonarthrosis, genu valgum, f lexion, and external rotation deformity is rarely encountered. Experie nce with five total knee arthroplasties in three patients with chronic patellar dislocation and gonarthrosis is reported. All knees had a mo dified proximal patellar realignment and arthroplasty with a constrain ed prosthesis. Preoperative Hospital for Special Surgery knee scores a veraged 55. Average follow-up period was 40 months. At latest follow-u p examination, the average Hospital for Special Surgery knee score was 83, the Knee Society knee score was 95, and the functional score aver aged 50. There was one complication: a full-thickness lateral skin nec rosis requiring flap coverage. The patellar score was zero in all knee s. Four knees had mild quadriceps weakness. Three knees rated as excel lent and two as good on both The Hospital for Special Surgery and Knee Society rating systems. Radiographic analysis revealed no radiolucent lines or osteolysis. The patellas were well centralized in the trochl ear groove in all patients. Patellar height averaged 14 mm (range, 12- 17 mm). In conclusion, satisfactory results were obtained by restoring axial alignment with a constrained implant and realigning the patella with an extensive proximal realignment.