Patella baja after displacement of tibial tuberosity for patellofemoral disorders.

The change of patellar height after the displacement of tibial tuberosity and its effect on the improvement of clinical signs of knees was studied. The anterior displacement of tibial tuberosity was performed on fourteen knees and the anteromedial displacement on twenty knees with patellofemoral arthrosis of twenty-nine patients, four men and twenty-five women with the age at operation ranging from 47 to 79 years (average: 58.3). The anteromedial displacement of tibial tuberosity was performed on ten knees and medial displacement on fifteen knees with recurrent patellar dislocation (eleven knees) or patellar subluxation (fourteen knees) of twenty-four patients, two men and women with the an age range from 14 to 37, (average: 22.4). Patellar height was measured on lateral view by the Insall-Salvati method using Ligament/Patella ratio (Lt/Lp ratio). Ligament/Patella ratio of the older group with patellofemoral arthrosis was decreased significantly (p < 0.01) after surgery, from 1.10 to 0.94. The ratio of the younger group with patellar dislocation or subluxation showed no significant changes, but of seven knees with high riding patella, which ratio revealed more than 1.2 before operation, decreased significantly (p < 0.001) from 1.47 to 1.31. The postoperative patella baja had no poor effect on the improvement of clinical signs.