Novel Plate Fixation of Tibial Tubercle Osteotomy in Revision Total Knee Arthroplasty: A Cadaveric Study

Background In the setting of revision total knee arthroplasty (RTKA), a tibial tubercle osteotomy (TTO) may be required to gain better exposure to the implant. However, complications still limit its use. The purpose of this study was to inform the design of a novel plate for TTO fixation in the setting of RTKA that reduces the occurrence of osteotomy displacement, nonunion, and malunion. Methods 44 knees from 22 adult cadavers previously dissected for instructional purposes were used in this study. Mean age of cadaver donors at death was 81.9 years (range, 41-101 years). Eight standardized measurements were collected on each knee and included measurements of the patellar tendon footprint as well as the footprint’s spatial relation to the plate. Descriptive statistics were calculated, and statistical significance was evaluated. Results The measurements were evaluated with respect to sex and showed statistical significance (p<0.05) between men and women for all measurements except Distal Footprint Width (p=0.070). On the lateral aspect of the proximal tibia, an average of 6 of 8 holes on the lateral limb of the plate were not contacting the tibia, suggesting modification of the length and angulation of the lateral limb. The current distance from the proximal to distal aspect of the plate is 100mm, adequately bypassing the end of the tibial tubercle in all cases. The current crosspiece sufficiently bypasses the footprint in 91% (40/44) of tibias, demonstrating that one crosspiece at its current position was sufficient. The plate’s proximal inner width was sufficient measuring 44mm as the mean Proximal Footprint Width measured 23.3mm with a maximum of 30.3mm. Conclusion In considering the current plate design, modifications should include converging more at the distal aspect of the lateral portion of the plate and shortening the plate by one hole on the lateral side, necessitating side specific plates.