Elution Profiles of Synthetic CaSO4 Hemihydrate Beads Loaded with Vancomycin and Tobramycin.

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.

The evolution from the two stage to the one stage procedure for biofilm based periprosthetic joint infections (PJI).

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.

New methods for the detection of orthopedic and other biofilm infections.

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.

Extrapleural benign solitary fibrous tumor in the shoulder of a 9-year-old girl: case report and review of the literature.

We report a case of a benign solitary fibrous tumor that occurred in the right shoulder of a 9-year-old girl. This case is remarkable due to the unusual location of its occurrence and the young age of the patient. In addition, cytogenetic analysis revealed a karyotype unreported in this neoplasm: 46,XX,der(4)t(4;9)(q31.1;q34), del(9)(p22p24),der(9)t(4;9)(q31.1;q34)ins(9;?)(q34;?) (17 cells)/46,XX (3 cells).

Skip metastasis in osteosarcoma.

Skip metastasis is rare in high-grade osteosarcoma and indicates a very poor prognosis. The authors describe two patients who had high-grade osteosarcoma and skip metastasis. MRI detected the skip lesion in both patients, and both lesions were confirmed by histology. The patients were treated with adjuvant chemotherapy and radical surgical resection. Both are alive and free of disease 3 and 6 years from diagnosis.

Revision total hip arthroplasty.

Endoscopic visualization and pneumatically-powered ballistic chisels that can be used to remove cement and cementless prostheses are recent developmental improvements for revision total hip arthroplasty (THA). Use of these new tools facilitates the revision procedure, reduces tissue trauma, and may reduce surgical time. Understanding the anatomy of the hip joint, pathophysiology that leads to the need for joint replacement, and the implant selection process can assist perioperative nurses in caring for and teaching patients who require revision THA and their family members. This article describes implant choices based on the type of bone deformity present and the use of the ballistic chiseling system during revision THA. Potential postoperative complications also are described.

Variability in dose intensity of high-dose methotrexate for nonmetastatic osteosarcoma.

The authors evaluated their ability to maintain planned dosing schedules for high-dose methotrexate (HD-MTX) in patients with nonmetastatic osteosarcoma. Twenty-seven patients who received therapy according to 2 POG protocols (8651 and 9351), both of which included HD-MTX (12 g/m(2)/week for 2 consecutive weeks), between 1988 and 1998 were studied. Significantly fewer HD-MTX infusions were given on the second week to patients treated on POG 9351 (33 vs. 93%; p < .0001). The hydration guidelines were identical and there was no difference in peak serum MTX levels either within or between protocols. Differences in the administration of combination chemotherapy in 9351 compared to 8651 may have contributed to the increased toxicity associated with HD-MTX on 9351, although this is speculative. The use of HD-MTX should be carefully planned so that it does not decrease its dose intensity or that of other effective agents.