Background: Change in the position of the patella in relation to the tibiofemoral joint (PB/PPB) is an important but often neglected complication of total knee arthroplasty. Such change may result in pain and decreased knee range of motion after surgery. The aim of this study is to measure the incidence of patella baja and pseudo-patella baja after total knee arthroplasty.  Methods: In a retrospective study, 60 patients (49 women, 11 men) who had knee arthroplasty between 1992 and 2002 at Akhtar teaching Hospital in Tehran were studied for patellar problem. At the time of the study, patients were at least one year and at most eleven years from their operation. All measurements were made by a single person. All the patients received posterior cruciate ligament retaining prosthesis knees through a medial parapatellar arthrotomy. The average age at the time of the study was 62.5 years and the average follow-up was 27.5 months. The Knee Society Scoring System was used to score the knees. Patients' radiographs were examined using the Insall Salvati and Blackburne Peel methods.     Results: Pseudo-patella baja was found in 15 (25%) patients while simultaneous baja and Pseudo-patella baja in 2 (3%) patients. While patella baja or Pseudo-patella baja were associated with more incidence of knee pain or limitation of motion, no relation was seen with final knee society scores.Conclusion: Patella baja or Pseudo-patella baja after knee arthroplasty may cause pain or limitation in knee range of motion. Attention to proper bone cuts and patellar tracking during surgery is suggested.