Chronic Oral Antibiotics Boost 5-Year Infection-Free Implant Survival after Certain PJIs
Along with the sharply rising number of total hip and knee arthroplasties performed in the US comes an increasingly compelling need to prevent periprosthetic joint infections (PJIs). If a PJI occurs, guidelines recommend a two- to six-week post-revision course of pathogen-specific intravenous antibiotic therapy. However, the benefit of chronic suppression with oral antibiotics beyond that is unproven.
In the August 5 edition of The Journal of Bone & Joint Surgery, Siqueira et al. compared the infection-free prosthetic survivorship in 92 patients who underwent chronic oral antibiotic suppression for a minimum of six months with prosthetic survivorship in a matched cohort who did not receive extended antibiotic treatment. In so doing, they also attempted to determine factors associated with failure of chronic suppression with oral antibiotics.
The five-year infection-free prosthetic survival rate in the suppression group was 68.5% compared with 41.1% in the non-suppression group. Patients who benefited the most from chronic suppressive antibiotic therapy were:
- Those who underwent irrigation and debridement with polyethylene exchange. (Antibiotic suppression following two-stage procedures did not affect prosthetic survival.)
- Those with Staphylococcus aureus (Chronic antibiotic therapy did not influence infection-free survival after revisions for non-S. aureus infections.)
Suppression-group patients in whom antibiotic treatment failed had had more prior joint revisions and were more likely to have had a knee PJI than a hip infection.
Noting the benefit of suppressive therapy in patients who underwent irrigation and debridement with polyethylene exchange, the authors concluded that “persistence of a latent infection is common in patients with retained implants, and thus antibiotic suppression seems to be a reasonable alternative that avoids the need for a more invasive two-stage revision.”
Meniscal Transplants in Young Patients: Great While They Last
Meniscal transplantation is often recommended after total meniscectomy for patients younger than 50 who remain symptomatic and show articular cartilage deterioration. But for how long are these transplants effective?
That’s what Noyes et al. attempt to answer in a survivorship analysis in the August 5, 2015 Journal of Bone & Joint Surgery. Extending the follow-up from a JBJS study they published in 2005, the authors tracked 40 cryopreserved menisci implanted into 38 patients for an average of 11 years. They measured transplant survival in two distinct ways:
- In terms of symptom-driven endpoints, including transplant removal, revision, or tibiofemoral compartment pain
- In terms of additional asymptomatic “worst-case” endpoints, including grade-3 signal intensity, extrusion (>50% of meniscal width), evident meniscal tear (per MRI or physical examination), or radiographic loss of joint space.
Using Kaplan-Meier survivorship analyses, Noyes et al. estimated transplant survival according to the first set of criteria as follows:
- 88% at 5 years
- 63% at 10 years
- 40% at 15 years
Using the more clinically stringent worst-case criteria, the authors estimated transplant survival as follows:
- 73% at 5 years
- 48% at 10 years
- 15% at 15 years
From these numbers, the authors conclude that “most (if not all) meniscal transplants will undergo a deleterious remodeling process at different time periods postoperatively.” They therefore stress that “patient candidates…should be advised that the procedure is not curative.”
Nevertheless, Noyes et al. emphasize that meniscal transplantation provides many patients with substantial short- and medium-term improvements in knee pain and function and that “there are patients who demonstrate worst-case imaging findings who remain relatively asymptomatic for several years.”
Ultimately, the authors say this study gives clinicians “reasonable survival percentages with regard to the potential to delay the necessity for subsequent major procedures.”
Good Grip Is Key to All-Inside Meniscal Repair
Many meniscus-preserving arthroscopic treatments for meniscus tears have evolved in recent years, including all-inside repairs. Advantages of all-inside techniques include shorter surgical times and reduced risk of damage to neurovascular tissues. Potential drawbacks include risks of local soft-tissue irritation, chondral injury, synovitis, and implant migration or breakage.
One recent generation of all-inside devices, known as FAST-FIX, consists of two polymer anchors connected by a nonabsorbable polyethylene suture in a preloaded delivery needle. In the July 22, 2015, JBJS Case Connector, Rauck et al. presented two cases in which FAST-FIX anchors came loose postoperatively, causing patients to develop knee pain and mechanical symptoms within two to six months after surgery.
To shed additional light on the anchor pullouts described by Rauck et al., we posted a “Watch” article and spoke with Tim Spalding, FRCS, consultant orthopaedic surgeon at the University Hospital in Coventry, England. Dr. Spalding has used FAST-FIX as his main meniscal-repair system for several years.
To minimize potential risks, Dr. Spalding encouraged surgeons to use the supplied slotted cannula when inserting the FAST-FIX delivery needle. “The slotted cannula helps you manipulate the meniscus and steer the needle to exactly where you want it,” Dr. Spalding said.
Perhaps the most important key to success with FAST-FIX is using it in areas of the meniscus that provide strong holding tissue. According to Dr. Spalding, the best grip site for FAST-FIX anchors is the posterior third of the medial meniscus, while tears of the lateral meniscus, especially those near the popliteal hiatus, represent the biggest grip-hold challenge.
“Anchors are not the magic fix some surgeons think they are,” Dr. Spalding concluded. “When they work, they’re simple, fun to use, and you can suture the meniscus in a few seconds, but this major advance might prompt some surgeons to use it in suboptimal situations or with hasty technique.”
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