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.

A definitive consensus on the optimal limb salvage protocol for infected total joints does not currently exist. Popular, is the two-stage revision which calls for the use of an antibiotic loaded spacer followed by a delayed exchange. Our question is whether single-stage revisions for biofilm based infected arthroplasties results in comparable or possibly better patient outcomes as compared to those reported for two-stage revisions. We retrospectively reviewed 500 cases of one-stage revisions for periprosthetic joint infections (PJI) using dual setup with radical debridement, definitive reconstruction with antibiotic loaded cement and implantation of antibiotic calcium sulfate pellets between the years 2005–2017. The revisions included 351 total knees, 122 hips, 2 hip-femur-knees, 13 shoulders, 10 elbows, and 2 shoulder-humerus-elbows. The patient population had a mean follow-up of 60 months (range: 24 months–14 years) and mean patient age of 61 years old, consisting of 250 males and 250 females. Patient comorbidities were reviewed, classified using McPherson’s staging for PJIs, and compared to the Cierny & Mader classification system. Successful treatment was defined as a joint without recurrence of infection, for a minimum of 2 years, and limb preservation. Based on our findings, one-stage revision of PJIs demonstrates at least as good an infection eradication rate as two-stage revision: 88% vs 85% respectively.

The use of local antibiotic delivery systems is common in the management of biofilm-related infections as they provide high concentrations of local antibiotics while simultaneously avoiding complications from systemic toxicity. Older delivery mechanisms were associated with a high incidence of wound complications (up to 25%) requiring reoperation. The high wound complication rate was thought to be due to impurities from the mined calcium sulfate, hydrophobic behavior, and acidic pH. We are presenting a 100% pure synthetic calcium sulfate hemihydrate (PSCSH) powder mixed with 240 mg liquid tobramycin and 500 mg of vancomycin powder per 10 cc of the hemihydrate for use in revision surgeries for periprosthetic joint infections (PJI). The purified carrier demonstrates superior utility to similar vehicles such as poly-methyl-methacrylate (PMMA) due to the bioabsorbablity which takes 2-3 weeks as demonstrated by disappearance of the hydrated crystal on x-ray. This is also preferable to the 4-6 weeks bioabsorbablity seen in the mined crystal calcium sulfate variants. The physiological pH of the PSCSH and the hydrophilicity demonstrated in serum probably account for the low 4% wound complication rate. The elution of vancomycin and tobramycin was greatest on day 1 compared with those concentrations obtained on days 2, 3, 4, and 5 post-operative while serum concentrations were mostly undetectable. Our findings demonstrate that this PSCSH preparation provides therapeutic delivery of vancomycin and tobramycin locally at log 2-3 above the minimum inhibitory concentration (MIC), while avoiding dangerous serum concentrations.

Aim: Currently, there are not many studies on the long-term outcomes of the specific implants used in patients with metal hypersensitivities. The purpose of this study is to report a significant number of TKA revision failures with the CFR-PEEK prosthetic knee implant with an anatomic hinge. Background: Patients can experience multiple issues following a primary Total Knee Arthroplasty (TKA). A growing body of research is finding a correlation between primary TKA failure and metal hypersensitivity, most commonly with nickel and cobalt. Because of this, knee prosthetics are being made from hypoallergenic metals, such as zirconium nitride (ZrN), to minimize the number of failures due to metal allergy. Given the relatively new development of the hypoallergenic prostheses, there is sparse data about their overall success. Objective: The purpose of this study is to report a significant number of TKA revision failures with the CFR-PEEK prosthetic knee implant with an anatomic hinge. Methods: In this study, we analyzed the sequelae of 84 patients between May 2015 to June 2020 who received a total knee revision due to a failed primary TKA with metal hypersensitivity. These patients were revised with the rotating anatomic hinge knee system, which consisted of Carbon Fiber Reinforced Poly-Ether-Ether-Ketone (CFR-PEEK implant) coated with a ZrN, Zirconium, and Chrome Nitride multi-layer surface coating with 30% polyacrylonitrile fiber content. The patients requiring an additional revision operation presented with increasing pain that showed evidence of osteolysis on plain radiographs, CT imaging, positive indium labeled WBC scans and increased uptake on bone scan. Intraoperatively, an open incisional biopsy of the surgical bed was obtained, followed by radical debridement and implantation of porex knee prosthesis. In addition, intraoperative findings included black debris that grossly stained the surrounding synovial tissue black, indicative of wear and debris from carbon fiber bearings and the anatomic hinge. Histology of the intraoperative biopsy showed the accumulation of black debris in the histiocyte, fibrosis, and perivascular cuffing of lymphocytes and multinucleated giant cells stained with black debris. Results: Of the 84 patients, 22 failed, requiring an additional revision procedure, equating to a 26 percent failure rate of the CFR-PEEK implant, averaging 25 months to failure. Conclusion: This study was meant to report the extremely high failure rate of the anatomic hinge secondary to carbon fiber debris. Perhaps carbon fiber-laden implants are not as good an option for total knee revision prosthesis because of the high failure rate compared to those with polyethylene in their hinge mechanism.

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? 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. 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. When used in one-stage revision arthroplasties, the bioabsorbable, purified carrier delivers high concentrations of antibiotic while avoiding systemic toxicity.

Laboratory cultures are the main scientific input into the decision-making process that determines the course of treatment for suspected orthopedic infections, just as they constitute the mainstay of the diagnosis of infections in other medical specialties. This situation is archaic because culture techniques were virtually abandoned in Environmental Microbiology (Hugenholtz et al. 1998) many years ago, following the conclusion that <1% of the bacteria in any natural ecosystem can be recovered by standard cultural methods. Medical Microbiology has clung to culture techniques because they detect the bacteria that cause acute infections, with reasonable sensitivity and accuracy, but the time has come to examine both their sensitivity and their accuracy for the detection and identification of bacteria in chronic biofilm infections (Costerton et al. 1999).

The detection and identification of bacteria present in natural and industrial ecosystems is now entirely based on molecular systems that detect microbial RNA or DNA. Culture methods were abandoned, in the 1980s, because direct observations showed that <1% of the bacteria in these systems grew on laboratory media. Culture methods comprise the backbone of the Food and Drug Administration-approved diagnostic systems used in hospital laboratories, with some molecular methods being approved for the detection of specific pathogens that are difficult to grow in vitro. In several medical specialties, the reaction to negative cultures in cases in which overt signs of infection clearly exist has produced a spreading skepticism concerning the sensitivity and accuracy of traditional culture methods. We summarize evidence from the field of orthopedic surgery, and from other medical specialties, that support the contention that culture techniques are especially insensitive and inaccurate in the detection of chronic biofilm infections. We examine the plethora of molecular techniques that could replace cultures in the diagnosis of bacterial diseases, and we identify the new Ibis technique that is based on base ratios (not base sequences), as the molecular system most likely to fulfill the requirements of routine diagnosis in orthopedic surgery.

The detection and identification of bacteria present in natural and industrial ecosystems is now entirely based on molecular systems that detect microbial RNA or DNA. Culture methods were abandoned, in the 1980s, because direct observations showed that <1% of the bacteria in these systems grew on laboratory media. Culture methods comprise the backbone of the Food and Drug Administration-approved diagnostic systems used in hospital laboratories, with some molecular methods being approved for the detection of specific pathogens that are difficult to grow in vitro. In several medical specialties, the reaction to negative cultures in cases in which overt signs of infection clearly exist has produced a spreading skepticism concerning the sensitivity and accuracy of traditional culture methods. We summarize evidence from the field of orthopedic surgery, and from other medical specialties, that support the contention that culture techniques are especially insensitive and inaccurate in the detection of chronic biofilm infections. We examine the plethora of molecular techniques that could replace cultures in the diagnosis of bacterial diseases, and we identify the new Ibis technique that is based on base ratios (not base sequences), as the molecular system most likely to fulfill the requirements of routine diagnosis in orthopedic surgery.