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Chronic suppressive antibiotic therapy
0%
1/757
Debridement, exchange of all modular components, and long term antibiotics (DAIR)
3%
25/757
One-stage exchange arthroplasty with dynamic spacer placement
1%
7/757
One-stage exchange arthroplasty with gastrocnemius flap coverage
3/757
Two-stage exchange arthroplasty with temporary static spacer
95%
718/757
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This patient presents with a chronic periprosthetic joint infection (PJI) of her total knee replacement (TKA) with an identified resistant organism. She should undergo two-stage revision arthroplasty (Answer 5) with a temporary static spacer given the lack of collateral ligamentous stability. Revision arthroplasty is associated with higher costs, mortality, and complication rates compared to primary arthroplasty procedures. Currently, two-stage revision arthroplasty is considered the gold-standard treatment for chronic PJIs. However, there has been a growing interest in the utilization of one-stage revision arthroplasty for the treatment of hip and knee PJIs. Proponents of one-stage exchange arthroplasty cite the comparably lower patient morbidity, avoidance of second-stage major procedures, decreased costs, and shorter treatment duration when compared to the standard two-staged treatment approach. However, the success rates of one-stage arthroplasty are generally inferior to two-stage treatment in the setting of multiple complex comorbidity/immunocompromised hosts, highly virulent/resistant organisms, and atypical PJIs (i.e. fungal). Given this patient’s infection with a methicillin-resistant enterococcus species, she would best be treated with a two-stage revision arthroplasty. Given the lack of medial/lateral collateral ligamentous support from her prior implant, a static spacer (stage 1 surgery, Illustration A) would be more appropriate to use than a dynamic spacer. After 6 weeks of antibiotics, this patient underwent a one-month antibiotic holiday with labs/aspiration confirming no detectable residual infection followed by a second-stage re-implantation procedure.Charette and colleagues provided an overview of two-stage revision arthroplasty to include diagnosis, treatment options, and operative techniques. They discuss the key differences between static and dynamic spacers for TKA in which static spacers are indicated in patients with severe uncontrolled infection (i.e. septic), ligamentous laxity, extensor mechanism dysfunction/insufficiency, those requiring flap coverage, or those with severe bone loss after prosthesis explantation. However, they note that static spacers lead to soft tissue stiffness that makes the second stage procedure more technically difficult with the need for more extensive exposure/releases. The authors note that dynamic spacers do have significantly improved knee range of motion after the second stage procedure while maintaining soft tissue tension; however, this does not impart improved functional outcomes nor superior infection eradication. The authors conclude that dynamic spacers are overall better to use with the exception of the aforementioned static spacer indications. Thakrar and colleagues performed a systematic review of one-stage revision arthroplasty and risk factors for persistent infection. They reported that patients at risk for one-stage revision include those with multidrug-resistant and fungal microbiologic profile infections, immunocompromised hosts, or preoperative soft tissue/boney deficits. The authors concluded that single-stage exchange arthroplasty remains an acceptable form of surgical treatment in well-indicated patients. They stressed the importance of awaiting the results of current multicentered randomized control trials prior to drawing definitive conclusions. Citak and colleagues reviewed their institutional risk factors for failure after one-stage exchange revision TKA for PJIs. The authors analyzed 91 patients who failed one-stage treatment over a 10-year period and compared them to a 1:1 propensity-matched control group (i.e. patients who did not require revision after one-stage attempt). They utilized binary logistic regression analysis and reported that patients with prior history of one- or two-stage exchange arthroplasty, enterococci infections, or streptococci infections were at increased risk for failure of one-stage revision exchange procedures. Figure A displays the presenting AP and lateral radiographic images of this patient’s posterior stabilized (PS) TKA. Illustration A displays a static antibiotic spacer fabricated out of a tibial intramedullary nail, antibiotic-imbued cement, and antibiotic-imbued PMMA beads. Incorrect Answers: Answer 1. Chronic suppressive antibiotic therapy is reserved for PJI patients with considerable comorbidities that otherwise preclude them from having surgery. Answer 2. Debridement, exchange of all modular components, and long-term antibiotics (DAIR) has been described for the management of acute postoperative and hematogenous PJI. In general, DAIR is not recommended in the setting of high-resistance organisms, nor is it recommended for chronic periprosthetic joint infections due to the high rate of failures (i.e. persistent infection). Answer 3. One-stage exchange arthroplasty alone could be considered in a healthy host without a high-resistance organism. Further, a dynamic spacer is generally contraindicated with gross ligamentous laxity. Answer 4. The presence of a draining sinus tract does not translate to the need for flap coverage. Draining sinus tracts should be excised via an elliptical incision during the two-staged approach, and the majority of small wounds can be primarily closed.
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