[Recentering the patella in the treatment of external femoropatellar arthrosis with displacement of the patella]. 
The authors report their experiences of the surgical treatment of external femoro-patellar arthrosis with displacement of the kneecap, by recentering the kneecap, on knees that were not deformed as seen from the front.  This recentering of the kneecap, which was monitored during the operation by radiographs with axial projection, was obtained by internal transposition of anterior tibial tuberosity and section of the external " wing " of the patella.  No inert or living material was placed between the patella and the trochlea.  The reduction in pain and the improvement in articular function depend on how well the patella is recentered.  Twenty-two cases of external femoro-patellar arthrosis with displacement of the kneecap were treated in this way; in 18 operations, 14 results that remained favourable for more than 6 months have encouraged the authors to continue their trials and to abandon, at least for the time being, patellectomies and patelloplasties.