Knochenersatzwerkstoffe als lokale Wirkstoffträger: Aktueller Stand bei Ersatzstoffen verschiedenen Ursprungs

Treatment of High-Grade Chronic Osteomyelitis and Nonunions with PerOssal®: A Retrospective Analysis of Clinical Efficacy and Patient Perspectives

Background/Objectives: Traditional autologous bone grafts as a treatment for bone defects have drawbacks like donor-site morbidity and limited supply. PerOssal®, a ceramic bone substitute, may overcome those drawbacks and could offer additional benefits like prolonged, local antibiotic release. This study investigates the clinical and radiological outcomes, including patient-reported outcomes, of using PerOssal® in nonunions (NU) and high-grade chronic osteomyelitis (COM). Methods: A single-center, retrospective study, investigating patients treated with PerOssal® between January 2020 and December 2023. Collected data include patient characteristics as well as various surgical and outcome parameters including the Lower Extremity Functional Scale (LEFS). Results: A total of 82 patients were analyzed. Reinfection occurred in 19.5% of cases. Osseous integration of PerOssal® was achieved in 89% of cases, higher in cavitary defects (91.5%) than segmental defects (72.7%). The revision rate was 32.9%, mainly due to wound healing disorders and reinfections. Mean LEFS score was 53.4 which was heavily influenced by sex (male: 50.7 vs. female: 63.4), revision surgery (no: 55.7 vs. yes: 49.1), reinfection (no: 56.6 vs. yes: 39.4), and osseous integration of PerOssal® (yes: 55.8 vs. no: 38.4). Conclusions: PerOssal® demonstrates promising outcomes in treating NUs and high-grade COM, especially in cavitary defects, with high osseous integration rates and acceptable functional results. However, reinfection remains a concern, particularly with difficult-to-treat pathogens and extensive surgical histories. Early, comprehensive surgical intervention and tailored antibiotic strategies are essential. Patient selection, defect characteristics, and comorbidities significantly influence success. Further research is needed to optimize treatment protocols.

[Bone cement as a local antibiotic carrier]

BACKGROUND

There is widespread consensus that adjuvant local use of antimicrobial agents in combination with their systemic administration can better prevent and treat implant-associated musculoskeletal infections. The advantage of local antibiotics lies in their particular pharmacokinetics with initially high antibiotic concentrations at the implant site with only low systemic uptake.

AIM OF TREATMENT

The aim of local application is to protect the foreign bodies directly at the implantation site from bacterial colonization and biofilm formation (prophylaxis) and to support the eradication of an already established infection after surgical debridement (treatment). Since the observations of Prof. Buchholz, bone cement has been the most frequently used local carrier system.

APPLICATION

In cases of infection, surgeons should ideally work together with microbiologists, infectiologists or clinical pharmacists to determine which anti-infective agents are indicated systemically for the patient and which ones are indicated locally with PMMA cement, based on the pathogen(s) and antibiograms. However, for the anti-infective agents administered with bone cement, there is still uncertainty about which agents can be added to this carrier material and at what concentrations. Accordingly, the authors of this review article not only summarize the rationale and evidence for local antibiotic use but also elaborate on the points that must be considered for admixing these agents to the cement.

Properties of Orthopaedic Cements Biomechanically Little Affected by Exceptional Use of Liquid Antibiotics

OBJECTIVES

To specify the concentration of the liquid antibiotics to be added to polymethylmethacrylate (PMMA) and its impact on the quality of the spacer is the purpose of this study with liquid clindamycin added to different cements.

METHODS

In the present study, eight different cement mixtures were prepared and investigated. In the following, number 1 indicates the references, 2 all cements after liquid clindamycin was added to the liquid cement compound, 3 all cements after liquid clindamycin was added to the cement powder, and 4 all cements after liquid clindamycin was added to the cement dough. After curing, cements were filled into metal moulds and a pressure of 3 bar was maintained for 30 min. Mechanical investigations were carried out according to ISO 5833 (2002) and DIN 53435 (2007). For microbiological tests, standardized cylindrical mouldings (diameter: 25 mm, height: 10 mm) were produced and incubated in 10 ml buffer solution at room temperature for 24 h. All eluates were generated by spreading previously established suspensions of Staphylococcus aureus, Staphylococcus epidermidis, Cutibacterium acnes and methicillin-resistant Staphylococcus aureus (MRSA) with a 0.5 McFarland turbidity standard.

RESULTS

Apparently, we found that in all investigated cases, the admixture of liquid antibiotic negatively affected the mechanical characteristics of the cement mould. Among the various test groups, the influence on the ISO compression strength and ISO flexural modulus of the investigated test groups was only minimal when liquid clindamycin was added to cement liquid. Compared to admixing of liquid clindamycin into cement powder or dough ISO compression strength and ISO flexural modulus and flexural strength showed the maximum reduction. The efficacy against chosen germs was reduced as well when liquid antibiotic was admixed instead of powder. This admixture of liquid anti-infective agents resulted in a 234% enhanced elution after 10 days 29 a negative effect on the inhibition zones were detected during the previous period.

CONCLUSION

The admixture of powdery antibiotic is preferable to liquid antibiotics. If no powdery antibiotic is available, we can recommend the admixture of liquid antibiotic to liquid cement prior to dough production in case powdery antibiotics cannot be used. However, we discourage the admixture of liquid antibiotic to cement powder or cement dough during early low viscose phase.

[Polymethyl methacrylate cement coating of intramedullary implants : A new technique for revision surgery with the example of a temporary knee arthrodesis. Video article]

BACKGROUND

The coating of intramedullary rods with polymethyl methacrylate (PMMA) bone cement containing antibiotics ensures a high concentration of antibiotics locally and stability in fractures that are not yet consolidated. However, bone cement can detach when the implant is removed and remain in the medullary cavity of the long bones.

CASE REPORT

After a periprosthetic knee infection, a 56-year-old patient suffered from a painful reinfection of Staphylococcus epidermidis. This was an indication for removal of the prosthesis.

OPERATION

After soft-tissue debridement and synovectomy, rotating hinge prosthesis that had been inserted was removed. Humeral nails coated with PMMA cement containing antibiotics were used as temporary intramedullary implants. To prevent the bone cement from detaching when the implant was removed and cement residue from remaining in the bone, the humeral nails were reinforced with cerclage wire. The coated implant was then press fit into the medullary cavity.