Description
Objectives: Posterior tibial slope (PTS) is defined by the inclination of the tibial plateau in the sagittal plane. Whilst understanding of its role in the kinematics of TKA has increased, its influence on clinical and functional outcomes between implant designs and type of constraint used remain unclear.
The aim of this study was to evaluate whether a significant change between the native and the prosthetic tibial plateau PTS influences functional results and the risk of complications following TKA. Our hypothesis was that the change in PTS ≤ 10° would achieve optimum outcomes.
Methods: This was a retrospective, single-center comparative study. Clinical and radiological data from 793 knees were collected from a prospective surgical database. Inclusion criteria were all patients operated with a fixed or mobile plateau PS TKA for primary tibiofemoral osteoarthritis, with or without associated patellofemoral osteoarthritis, or osteonecrosis of the femoral condyle or tibial plateau, with a minimum follow-up of 5 years. Range of motion and International Knee Society (IKS) score as well as radiological measurements were collected preoperatively and postoperatively at each follow-up visit. Two groups were composed according to the change in PTS between pre- and post-op (Group 1: ≤10°, n=703; Group 2: >10°, n=90).
Results: The mean follow-up was 75.5 months ± 19.1. The mean change in PTS from preoperative was 4.96° ± 3.24 in group 1 and 12.7° ± 1.87. There was no significant difference in the mean IKS Knee subscore (89.5 ± 10.7 and 89.7 ± 10.2, p=0.89) and mean IKS Function subscore (88.2 ± 15.7 and 86.3 ± 16.6, p=0.33) in groups 1 and 2 respectively. Postoperative maximum flexion was very satisfactory in both groups with no clinically relevant difference (120.0 ± 11.9 and 123.0 ± 8.3, p=0.026). Complication rate was 5.0% (n=40) while the most common complication requiring further procedure was deep infection (n=9, 1.1%) and the second most common was stiffness (n=6, 0.8%).
Conclusions: Even a significant change in PTS does not influence postoperative maximum flexion and clinical scores and is not associated with a higher complication rate at a minimum 5-year follow-up after PS-TKA.
