Background

Antibiotic-impregnated pellets and cement are commonly used as treatment for osteomyelitis and biofilm-related infection. We studied the utility of 100% pure synthetic calcium sulfate hemihydrate pellets impregnated with 240 mg liquid tobramycin and 500 mg vancomycin powder per 10 cc mixture (PSCSH-TOB-VAN) in both septic and aseptic one-stage revision arthroplasties for total hips and total knees. These beads are biodegradable and provide concentrations between 100-1000 times MIC locally without detectable levels in the serum. These pellets soften secondary to hydration almost instantly when placed in a surgical bed.

Methods

466 patients from 2016-2019 were reviewed in a retrospective study. We reviewed patient demographics, physical exam findings, and patient history along with routine labs, and staging studies (bone scan, WBC scan, and CT) to identify patients. We also analyzed the volume of PSCSH-TOB-VAN used and complications such as postoperative drainage and heterotopic ossification.

Results

Of the 466 patients included in this study, 202 are male and 264 are female. The average age was 62 years with a range from 20 to 92 years. The average BMI of our patients was 31.8. 159 patients (34.1%) had periprosthetic joint infections (PJI) as their preoperative diagnosis, of these, 150 (94.3%) had McPherson III-C-3 PJI. PSCSH-TOB-VAN disappeared on x-ray imagery an average of 3 weeks postoperatively. The average volume of PSCSH-TOB-VAN used in these patients was 24 mL with a range from 20-100 mL, depending on the size of the incision site. 133 of our patients (28.5%) had postoperative drainage due to increased PSCSH-TOB-VAN volume usage, most of which were able to be treated conservatively with a wound vac. 37 patients (0.08%) needed reoperation due reinfection.

Conclusion

With our 466 patients as evidence, PSCSH-TOB-VAN is an acceptable tool to be used in an antibiotic carrier with high elution profiles that can kill biofilm. It can be used in infected knees postsurgically and in infected arthroplasties to significantly reduce recurrence of the infection. Since PSCSH-TOB-VAN is soft upon hydration, it does not scratch the cartilage in knees or the joint in the treatment of PJI. At local elution levels of antibiotic at 100-1000 times MIC, without detectable serum levels of the antibiotics, PSCSH-TOB-VAN kills biofilm and is safe to use. With further studies, PSCSH could potentially provide high dosing of a variety of other local drug treatments, including chemotherapeutic agents such as doxorubicin, and pain control targeting opioid receptors. This could be extremely beneficial in mitigating systemic effects of the drugs.