HONGSEN CHIANGJiang C.-C.2020-07-012020-07-0120102210-7940https://www.scopus.com/inward/record.uri?eid=2-s2.0-79955963506&doi=10.1016%2fj.fjmd.2010.10.002&partnerID=40&md5=f70097ffa3fe6c0a1f58d2515939aca4https://scholars.lib.ntu.edu.tw/handle/123456789/507519Background: Patella baja happens after revision total knee arthroplasty (TKA), by patellar ligament shortening and/or elevated joint line (" pseudo" patella baja), and may restrict knee flexion. Methods: We studied 29 revision TKA of the same surgical procedure and type of prosthesis with an average follow-up of 28.3 months. Results: At the last follow-up, patella baja was found in 59%, 83%, and 90% of patients, as defined by Insall-Salvati (IS), Blackburne-Peel, and Caton-Deschamps indexes, respectively. Higher incidence by the latter two indexes indicated existence of pseudo patella baja. Mean maximal flexion angle was 95.5°, poorly correlated with any of the three indexes by linear regression. Mean maximal flexion angle of IS index-defined patella baja knees (97.9°) was not significantly different from that of the nonbaja knees (92.1°). Mean IS index significantly decreased after surgery (0.82-0.78), but joint line position did not change significantly. Conclusion: Both true and pseudo patella baja could exist after revision TKA but would not restrict knee flexion. ? 2010, Taiwan Orthopaedic Association.[SDGs]SDG3adult; aged; article; clinical article; controlled study; female; follow up; human; joint limitation; joint mobility; knee disease; knee function; knee prosthesis; male; outcome assessment; patella baja; priority journal; surgical risk; surgical technique; total knee replacementjournal article10.1016/j.fjmd.2010.10.0022-s2.0-79955963506