Study: Better Range of Motion with Articulating Spacers for Infection After TKA

By: Terry Stanton

A prospective, multicenter, randomized trial presented Wednesday demonstrated that at short-term follow-up, articulating spacers provide significantly better range of motion when compared to static spacers in the treatment of periprosthetic joint infection (PJI) after total knee arthroplasty (TKA).

The study, presented by Peter N. Chalmers, MD, who performed the study while a resident at Rush University, also detected a trend toward increased frequency of tibial metaphyseal augment use at the time of reimplantation in the static group, suggesting that articulating spacers may reduce tibial bone loss.

In noting these findings for the two types of spacers, Dr. Chalmers explained that the study revealed no advantage of one technique over the other in terms of surgical complexity, as there was no difference in surgical times or the need for an extensile surgical exposure. There was also no difference in infection recurrence rates.

“The primary clinical takeaway of the study is that articulating spacers provide superior range of motion in the treatment of infection after total knee arthroplasty and that they may also reduce tibial bone loss,” Dr. Chalmers said. “However, both techniques provide equivalent infection control and operative complexity both at the time of spacer placement and TKA reimplantation.”

In reporting the study, the authors commented, “While many surgeons cite ease of revision at the second stage reimplantation as an advantage of an articulating spacer, among this group of fellowship-trained surgeons at tertiary care centers, we were unable to demonstrate that the second-stage reconstruction was easier for the surgeon as there was no difference in the need for an extensile surgical exposure or in operative time. Similarly although one might hypothesize that an articulating spacer may facilitate early discharge or a greater ability to return to home, no differences in this parameter were identified with the sample size studied.”

Dr. Chalmers noted, “Our study is ongoing both in terms of recruitment and follow-up and thus these preliminary results may certainly change as we complete the study.”

Abstract: “A Randomized Clinical Trial of Articulating and Static Spacers in the Management of Periprosthetic Knee Infection”

Background: Although the use of an interim antibiotic loaded spacer is considered standard for a two-stage exchange for PJI, the use of an articulating as opposed to a static spacer is controversial. The purpose of this multicenter, randomized control trial is to compare articulating and static spacers for the treatment of PJI after TKA.

Methods: 54 patients who met Musculoskeletal Infection Society criteria for PJI following a primary TKA at three centers were randomized: 28 into the articulating group and 26 into the static group. Antibiotics and reimplantation timing were
managed using the standard of care of each surgeon and institution. Power analysis determined that 56 patients were needed to identify a 13º difference in range of motion (ROM) between groups (β = 0.80 and α = 0.05). Demographics between the two groups were not significantly different, suggesting appropriate randomization.

Results: There was no difference in mean operative time, the need for an extensile surgical exposure, blood loss, or length of stay at the first or second stage surgeries. In the subset of 27 patients who had follow-up at a minimum of 1 year following reimplantation (mean follow-up of 1.7 years, range, 1.0 to 2.9 years), knee range of motion was significantly greater in patients who had an articulating spacer (113° vs. 100°, P = 0.033). The change in range of motion was also significantly greater in the articulating group (18 ±16° vs. 3 ± 18°, P = 0.045). There was a trend toward increased frequency of tibial metaphyseal augment use at the time of reimplantation in the static group (33% vs. 8%, P = 0.072), although mean composite polyethylene and tibial augment thickness was not different. 

Conclusions: This prospective, multicenter, randomized trial demonstrates that at short-term follow-up, articulating spacers provide significantly better range of motion when compared to static spacers in the treatment of PJI after TKA. There was no advantage of one technique over the other in terms of operative complexity as evidenced by operative times or the need for an extensile surgical exposure.                

Dr. Chalmers coauthors are Erdan Kayupov, MS; Scott M. Sporer, MD; Keith R. Berend, MD; Gregory K. Deirmengian, MD;  Javad Parvizi, MD, FRCS; Matthew Austin, MD; Antonia Chen, MD, MBA; and Craig J. Della Valle, MD.

Details of the authors’ disclosures as submitted to the Orthopaedic Disclosure Program can be found in the Final Program; the most current disclosure information may be accessed electronically at www.aaos.org/disclosure

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