Mackenzie A. Roof, BS, Jessica L. Baylor, BS, Jenna A. Bernstein, MD, Brielle J. Antonelli, BS, David N. Kugelman, MD, Alexander J. Egol, BS, Christopher M. Melnic, MD, Antonia F. Chen, MD, MBA, William J. Long, MD, Vinay K. Aggarwal, MD, Ran Schwarzkopf, MD, MSc

The Journal of Arthroplasty:  January 20, 2021
DOI:https://doi.org/10.1016/j.arth.2021.01.039

Summary by: Francis J Sirch IV, BS

Prosthetic joint infection (PJI) is the second most common cause of total knee arthroplasty revision and poses a significant financial burden to our healthcare system.^1–3 Given the significant costs associated with prosthetic joint infections (PJI), attempts to deliver safe effective treatments have resulted in a variety of options in operative management.  A common strategy is two-stage all-component revision with the use of an antibiotic-impregnated spacer between stage one and stage two surgery. Traditionally, surgeons are required to choose between number of subtypes of static and articulating antibiotic-impregnated spacers, but recent trials have reported that articulating spacers have greater range of motion (ROM) and improved long term patient outcomes as compared to static spacers.⁴ While articulating spacers may provide improvements in ROM , further investigation into what type of articulating spacer provides optimal patient outcomes has been limited.

In this study, Roof et al investigated the efficacy of articulating all-cement spacers and articulating real component spacers in patient ROM after stage one, and infection control in two-stage-all component revisions. They retrospectively reviewed 164 patients with confirmed PJI undergoing revision total-knee arthroplasty between 2011-2020. The cohort was further divided into 72 all-cement articulating spacers, and 92 real-component articulating spacers. This study found real component spacers had significantly greater pre-stage 1 ROM arc (96.3 ± 25.6° vs 86.4 ± 29.1°; P<.037), post-stage 1 ROM arc (83.6 ± 27.9° vs 58.2 ± 28.4°; P <.001), and ROM arc at most recent follow up (104.1 ± 21.7° vs 93.7 ± 28.0°; P <.016), but no differences between the two groups at post-stage 2 ROM arc. Real-component spacers had shorter hospital length of stay (LOS) after stage one (5.8 ± 4.3 vs 8.4 ± 6.8 days; P <.006) and stage two (3.3 ± 1.7 vs 5.4 ± 4.9 days; P <0.003), as well as lower estimated blood loss (224.2 ±155.7 vs 316.6 ± 210.5 mL; P <0.009) and operative time (162.2 ± 47.5 vs 188.0 ± 66.0 minutes; P<0.014).

The authors of this study concluded there were no differences in ROM from pre-Stage 1 to most recent follow-up between all-cement and real-component spacers. There was also no difference in time to reimplantation or reinfection rates following reimplantation. The authors found that real-component spacers had improvements in operative time, blood loss, and hospital LOS compared to all-cement articulating spacers. The authors conclude that these improvements suggest real-component spacers allow for easier reimplantation and improved patient recovery and may be superior to all-cement spacers. Limitations of this study include its retrospective nature. Additionally, as the institutions participating in this study were academic, a few patients had stage one procedures performed at outside institutions and subsequently transferred care with missing information. Lastly, all institutions participating were urban academic centers, potentially limiting the generalizability of the results to other patient populations.

References:

1. Delanois RE, Mistry JB, Gwam CU, et al. Current Epidemiology of Revision Total Knee Arthroplasty in the United States. J Arthroplast 2017;32:2663–8.
2. Zamora T, Garbuz DS, Greidanus NV, et al. An articulated spacer made of new primary implants in two-stage exchange for infected total knee arthroplasty may provide durable results. Bone Jt J 2020;102-B:852–60.
3. Sharkey PF, Lichstein PM, Shen C, et al. Why Are Total Knee Arthroplasties Failing Today—Has Anything Changed After 10 Years? J Arthroplast 2014;29:1774–8.
4. Nahhas CR, Chalmers PN, Parvizi J, et al. A Randomized Trial of Static and Articulating Spacers for the Treatment of Infection Following Total Knee Arthroplasty. J Bone Joint Surg 2020;102:778–87.