Durable infection control and function with the PROSTALAC spacer in two-stage revision for infected knee arthroplasty

Abstract

Background: A two-stage revision total knee arthroplasty is recognized as the gold standard in the treatment of infection. However, traditional spacers limit function in the interval between the two stages and may cause instability, scarring, and bone erosion. The PROSTALAC knee spacer is an antibiotic-loaded cement articulating spacer that allows some movement of the knee between stages. Whether motion enhances long-term function is unknown.

Questions/purposes: We therefore identify the rate of control of infection using the PROSTALAC exchange spacer and to assess the clinical outcome after implantation with a definitive implant.

Methods: We retrospectively reviewed 115 knees that underwent two-stage exchange with the PROSTALAC spacer. Forty-eight of these had a minimum followup of 5 years (mean, 9 years; range, 5-12 years).

Results: At last review, 101 of the 115 knees (88%) had no evidence of infection. Of the 14 knees that became reinfected, four were from the same organism and 10 were with a different organism. After further intervention, using the two-stage approach again, the infection was controlled in 12 of the 14 initially reinfected cases, resulting in a failure to cure in only two cases. We observed improvements in mean WOMAC, Oxford, UCLA, and Patient Satisfaction scores at last review.

Conclusions: The PROSTALAC functional spacer was associated with a 98% rate of control of infection and improvements in the quality-of-life outcomes in the treatment of chronically infected total knee arthroplasties.

Level of evidence: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Figures

Fig. 1

The final 1994 PROSTALAC design is shown just before implantation incorporating small polycentric metal runners, small inlaid polyethylene plateaus, a cam mechanism, and a posterior cross bar.

Fig. 2

The PROSTALAC components are shown implanted.

Fig. 3

An AP radiograph shows a PROSTALAC articulating knee spacer.

Fig. 4

The graph demonstrates the mean preoperative and postoperative WOMAC scores for the PROSTALAC knee. The WOMAC scores were normalized to a scale of 0 to 100 with 100 being a perfect score.

Fig. 5

The graph demonstrates the mean preoperative and postoperative Oxford, SF-12, and the postoperative satisfaction and UCLA scores. The Oxford scores were normalized to a 0 to 100 scale in which 100 is a perfect score.

Fig. 6

The 1987 handmade prototypical femoral component design is shown.

Fig. 7A–B

(A) The 1991 style femoral mold and (B) the implanted femoral and tibial acrylic components without the low-friction interface, which was developed later, are shown.