Abstract
Objective
The purpose of the present study was to compare the clinical and radiographic results after TKA using a patellofemoral design modified prosthesis and its predecessor. The other purpose was to investigate whether the use of the recent prosthesis increase the risk of posterior tibial cortex injury or patellar fracture.
Materials and Methods
The clinical and radiographic results of 300 knees which underwent TKA using the Attune®prosthesis (group A) were compared with those in a paired match-control group who underwent TKA using the P.F.C. Sigma® prosthesis (group B). The preoperative demographic data between the 2 groups did not differ significantly. The WOMAC, Feller and Kujala scores, and range of motion (ROM) were compared. The minimal distance between the tibial component stem to posterior tibial cortex, and the remnant patella thickness were compared.
Results
The postoperative WOMAC score was better in the group A than in the group B (17.7 vs. 18.8, p=0.004). The postoperative ROM was greater in the group A than in the group B (131.4° vs. 129.0°, p=0.008). The postoperative Feller score was not different, but postoperative Kujala score was better in the group A. The minimal distance between the tibial component stem and posterior tibial cortex was significantly shorter in group A than in the group B (6.3mm vs 7.0mm, p<0.001). The proportion of high risk group for posterior tibial cortical injury, which had the minimal distance less than 4mm, was higher in the group A (20.0% vs 10.7%, p=0.002). The remnant patella was thinner in the group A than in the group B (14.8mm vs 15.7mm, p<0.001). The proportion of high risk group for patella fracture with remnant thickness of <12mm was higher in the group A (7.5% vs 2.1%, p=0.003).
Conclusion
When comparing the clinical and radiographic results after TKA using the two prostheses of a design modified prosthesis and its predecessor, TKA using the recent prosthesis provided better satisfactory results. However, the risk of injury in the posterior cortex of the tibial metaphysis or remnant patella should be considered in this design modified prosthesis.
Level of Evidence
Level III
