Abstract
Background:
Polyethylene wear in total knee arthroplasty (TKA) is influenced by patient, surgeon and implant factors. The objective of this study is to assess the effect of limb alignment, implant position and joint line position on the pattern of wear in posterior stabilized (PS) tibial inserts.
Methods:
This was a retrieval analysis of 83 PS liners collected from patients who underwent revision surgery from 1999 to 2011. Inserts were divided into 16 zones and a microscopic analysis of surface damage was carried out. We determined overall damage with a scoring system. Pre-revisions radiographs were reviewed and analyzed for correlation with the wear profile.
Results:
The mean age was 73 years old (range 45 to 96 years old) and the mean duration of implantation was 3.5 years (range 0.1 to 10.6 years). The most common reason for revision was infection (71%, 59 of 83 liners), followed by aseptic loosening (6%, 5 of 83 liners) and instability (6%, 5 of 83 liners). The most common mode of wear was burnishing, followed by abrasion and pitting. The total damage score was significantly higher in knees with postoperative varus alignment more than 3 degrees (p = 0.03). Postoperative varus alignment was associated with significantly more wear in the medial compartment (p = 0.03). The total damage score to the post was significantly more in knees with joint line elevation more than 5 mm (9.7 ± 3.9, compared to 6.5 ± 3.7 in knees with less joint line elevation) (p = 0.05). The most commonly affected compartment was the medial compartment.
Conclusion:
Limb malalignment and implant malposition resulted in more wear in PS TKA.
