[Is use of the Knee Society Roentgenographic Evaluation and Scoring System for radiologic control of knee prostheses reliable?].

PURPOSE

To follow the radiographic parameters of prosthetic loosening of the Knee Society Roentgenographic Evaluation and Scoring System (KSRESS) and to test their clinical relevance.

METHODS

This prospective study documents the use of the KSRESS and clinical rating system in 333 primary posterior cruciate retaining PFC total knee arthroplasties preoperatively, at 3 month and at yearly intervals postoperatively. The average follow-up period was 3.2 years (range 2-5.5 y).

RESULTS

The average component position and alignment angles remained unchanged at biomechanically correct angles during the follow-up period. Radiolucent lines were observed regularly at the edges of the tibial and femoral components. The average total radiolucent lines score decreased for the tibial component. Patellar and femoral lucencies remained unchanged. The total radiolucent lines scores did not correlate with postoperative pain, body-mass-index, alignment, stability, knee and function score. Four revisions, one with relevant radiolucent lines, had to be performed.

CONCLUSIONS

The KSRESS is a useful tool. Standardisation of roentgenograms is mandatory. The PFC arthroplasty, the operative technique and the instruments ensure a biomechanically correct implantation.