Backgrounds and Objectives The use of local antibiotic delivery vehicles is common in the management of biofilm-related infections as they provide high concentrations of local antibiotics while simultaneously avoiding complications from systemic toxicity. We present a 100% pure synthetic calcium sulfate hemi-hydrate mixed with 240 mg tobramycin and 500 mg vancomycin per 10 cc mixture for use in revision surgeries of periprosthetic joint infections (PJIs). The purified carrier demonstrates bioabsorbablity, promotion of bone growth, a physiologically favorable pH, and hydrophilicity. These unique properties may alleviate persistent postoperative wound drainage seen in patients with PJI. Our questions consist of two parts: (1) does the novel calcium sulfate carrier provide therapeutic concentrations of antibiotic locally that can kill biofilm related infections? (2) Are serum concentrations of antibiotic significant to cause concern for systemic toxicity? Methods To address these questions, we assayed the elution of antibiotic concentrations obtained from surgical drains and serum among 50 patients in the first 5 postoperative days. Results The elution of vancomycin and tobramycin was greatest on day 1 compared with those concentrations obtained on days 2, 3, 4, and 5; serum concentrations were largely undetectable. Our findings demonstrate that this calcium sulfate preparation provides therapeutic delivery of vancomycin and tobramycin locally at log 2-3 above the minimum inhibitory concentration (MIC), while avoiding toxic serum concentrations. Conclusions When used in one-stage revision arthroplasties, the bioabsorbable, purified carrier delivers high concentrations of antibiotic while avoiding systemic toxicity.
Introduction:No good mechanisms are available for reconstruction of large anterior soft tissue defects associated with infected total knees [periprosthetic joint infections of the knee (PJI-K)]. Patellectomy is usually required due to involvement with adjacent large anterior soft tissue defects left after radical debridement, free flaps are required for closure. This type of flap necessitates the use of a drop lock brace in ambulation. Our question is whether the proximal placement of the knee joint with longer tibial segments can reduce the number of free flaps and reduce the need for a drop lock brace by reattaching the quadriceps directly to the hinged tibial component.
Methods:We retrospectively analyzed 35 cases with a minimum 2-year follow-up. Of 1-stage total knee revisions for PJI-K with the proximal placement of the knee joint for large anterior soft tissue defects left after debridement.
Results:The average knee joint displacement was 85 mm. Eleven recurred with infection and 4 required amputation. Eighteen had enough extensor power to walk with a cane or walker as opposed to requiring a drop lock brace. Fifteen patients did not need any free or local flaps, rather these patients only required adjacent soft tissue transfer during surgery.Discussion: This novel proximal placement of the knee joint in patients with PJI-K who have large anterior soft tissue defects lessens the need for free flaps. The proximal placement also allows for reconstruction of what is left of the quadriceps mechanism into the tibial component and usually provides enough extensor power to lock the hinge joint.
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