Restoration of the distal femur impacts patellar height in revision TKA

Clin Orthop Relat Res. 2012 Jan;470(1):205-10. doi: 10.1007/s11999-011-1995-7.


Background: Restoring patellar height is important in revision TKA for normal knee function and kinematics. Alteration in patellar height after revision TKA is associated with inferior extensor mechanism function.

Questions/purposes: We determined whether gap balancing with bone preservation and distal femoral augmentation would restore patellar height and patellar height changed in patients undergoing septic and aseptic revision TKA.

Patients and methods: We retrospectively reviewed 76 patients who had revision TKA between 2006 and 2009; 12 had two-stage revisions for infected TKA, and 64 had revision for aseptic failure. We compared preoperative and postoperative radiographs and measured the patellar height using the Insall-Salvati ratio in both groups. We reviewed operative records to determine type of exposure and amount of distal femoral augmentation used to restore the joint line.

Results: Overall mean preoperative and postoperative Insall-Salvati ratios were 1.02 and 1.04, respectively. In the septic group, mean preoperative and postoperative Insall-Salvati ratios were 1.07 and 0.99, respectively. In the aseptic group, mean preoperative and postoperative Insall-Salvati ratios were 1.01 and 1.05, respectively. Overall, nine patients had preoperative patella baja; seven of these had an improvement to normal height. There was little difference in preoperative and postoperative Insall-Salvati ratios in patients with patella alta. Distal augmentation was used in 10 of 12 patients in the septic group and 48 of 64 patients in the aseptic group.

Conclusions: Surgeons can maintain normal patellar height and improve patella baja by preserving bone stock and using distal femoral augments to restore the distal joint line during revision TKA.

Publication types

  • Comparative Study

MeSH terms

  • Aged
  • Aged, 80 and over
  • Arthroplasty, Replacement, Knee / adverse effects*
  • Arthroplasty, Replacement, Knee / methods
  • Cohort Studies
  • Female
  • Femur / diagnostic imaging
  • Femur / surgery*
  • Follow-Up Studies
  • Humans
  • Knee Prosthesis*
  • Male
  • Middle Aged
  • Patella / diagnostic imaging*
  • Patella / surgery
  • Prosthesis Design
  • Prosthesis Failure*
  • Radiography
  • Range of Motion, Articular / physiology*
  • Recovery of Function
  • Reoperation / methods*
  • Retrospective Studies
  • Risk Assessment
  • Treatment Outcome