In Vitro Elution of Gentamicin from CERAMENT® G Has an Antimicrobial Effect on Bacteria With Various Levels of Gentamicin Resistance Found in Fracture-related Infection.

BACKGROUND: Fracture-related infection is a serious complication after trauma. CERAMENT® G combines dead-space management with local release of gentamicin in a single-stage procedure. Bacterial resistance against antibiotics is increasing. The local effect of CERAMENT® G on bacteria resistant to systemically administered gentamicin is unknown. QUESTIONS/PURPOSES: (1) What is the in vitro elution pattern of gentamicin from CERAMENT® G using a full washout model? (2) What is the in vitro antimicrobial activity (zone of inhibition) of CERAMENT® G against bacterial isolates found in fracture-related infection with different susceptibility levels toward gentamicin? METHODS: Elution of gentamicin from CERAMENT® G was determined in vitro over a period of 2 months. Elution experiments were performed in fivefold, with gentamicin being sampled in threefold at 19 different timepoints within 2 months. Antimicrobial activity was determined using the four most-frequently cultured bacterial species found in fracture-related infection: Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Enterobacter cloacae . For each of the species, four different isolates with a different susceptibility to gentamicin were used. According to the European Committee on Antimicrobial Susceptibility Testing, the susceptibility of each isolate was classified into four different groups: fully susceptible (minimum inhibitory concentration 0.064 to 4 mg/L), minimally resistant (minimum inhibitory concentration 4 to 16 mg/L), moderately resistant (minimum inhibitory concentration 8 to 96 mg/L), and highly resistant (minimum inhibitory concentration 24 to 1024 mg/L), depending on each organism. The antimicrobial activity of CERAMENT® G was determined according to the European Committee on Antimicrobial Susceptibility Testing disk protocol. The experiment was performed in fivefold for each isolate. The zone of inhibition was compared between each bacterial isolate and within each of the four separate species. Nonlinear regression statistics were calculated between the zone of interest and logarithmic minimum inhibitory concentration for each bacterial species. RESULTS: After 24 hours, 95% of all available gentamicin was eluted, and gentamicin was still detectable after 2 months. CERAMENT® G showed antimicrobial activity against all bacterial species; only S taphylococcus aureus (with a minimum inhibitory concentration > 1024 mg/L) was not susceptible. The zone of interest of the different bacterial isolates was correlated with the logarithmic minimum inhibitory concentration. CONCLUSION: CERAMENT® G offers a bone substitute capable of releasing high levels of gentamicin within a short period of time. This study shows that CERAMENT® G has antimicrobial activity against bacterial isolates that are resistant to gentamicin when systemically administered. This finding raises the question of whether European Committee on Antimicrobial Susceptibility Testing cutoff points for systemic application are useful for the use of local CERAMENT® G. Standardized experiments to determine local antibiotic antimicrobial activity in fracture-related infection treatment are needed to form guidelines for the use of local antibiotics and ultimately improve fracture-related infection treatment. CLINICAL RELEVANCE: Local concentrations of gentamicin with CERAMENT® G are much higher than when systemically administered. It seems effective against certain bacterial strains that are not affected by systemically reachable concentrations of gentamicin. CERAMENT® G might still be effective when bacteria that are resistant to systemically administered concentrations of gentamicin are occulated from patients with fracture-related infection.

Influence of approach and implant on reduction accuracy and stability in lisfranc fracture-dislocation at the tarsometatarsal joint.

BACKGROUND: Besides early diagnosis, an anatomical and stable reduction is paramount for obtaining a favorable outcome. The current study looked at the influence that the type of approach for tarsometatarsal injuries has on the accuracy of the reduction and the effect that the type of fixation has on stability. METHODS: Consecutive patients treated surgically for an acute Lisfranc injury were included. All radiographs were reassessed for accuracy and secondary displacement following either a closed or an open approach and in terms of the type of fixation (Kirschner wires alone or a combination of screws and plates and Kirschner wires). A total of 28 patients were included. Six patients were treated with closed reduction and percutaneous fixation and 22 with open reduction internal fixation. Sixteen patients were treated with Kirschner wires only (6 closed, 10 open), 7 with screws with or without Kirschner wires, and 5 with medial plating with or without Kirschner wires. RESULTS: In the closed reduction group, 2 of 6 (33%) reductions were considered acceptable versus 19 of 22 (86%) in the open group (P = .021). All 6 secondary displacements occurred in the Kirschner wire fixation group (37.5%) versus none in the rigid fixation group (P = .024). CONCLUSION: The results demonstrate that open reduction and internal fixation with screws or plate resulted in better reduction and better maintenance of reduction in both low- and high-energy Lisfranc injuries. These results should be further evaluated in light of functional outcome. LEVEL OF EVIDENCE: Level III, retrospective comparative case series.

Combined anterior-posterior surgery versus posterior surgery for thoracolumbar burst fractures: a systematic review of the literature.

STUDY DESIGN: A systematic quantitative review of the literature. OBJECTIVE: To compare combined anterior-posterior surgery versus posterior surgery for thoracolumbar fractures in order to identify better treatments. SUMMARY OF BACKGROUND DATA: Axial load of the anterior and middle column of the spine can lead to a burst fracture in the vertebral body. The management of thoracolumbar burst fractures remains controversial. The goals of operative treatment are fracture reduction, fixation and decompressing the neural canal. For this, different operative methods are developed, for instance, the posterior and the combined anterior-posterior approach. Recent systematic qualitative reviews comparing these methods are lacking. METHODS: We conducted an electronic search of MEDLINE, EMBASE, LILACS and the Cochrane Central Register for Controlled Trials. RESULTS: Five observational comparative studies and no randomized clinical trials comparing the combined anteriorposterior approach with the posterior approach were retrieved. The total enrollment of patients in these studies was 755 patients. The results were expressed as relative risk (RR) for dichotomous outcomes and weighted mean difference (WMD) for continuous outcomes with 95% confidence intervals (CI). CONCLUSIONS: A small significantly higher kyphotic correction and improvement of vertebral height (sagittal index) observed for the combined anterior-posterior group is cancelled out by more blood loss, longer operation time, longer hospital stay, higher costs and a possible higher intra- and postoperative complication rate requiring re-operation and the possibility of a worsened Hannover spine score. The surgeons' choices regarding the operative approach are biased: worse cases tended to undergo the combined anterior-posterior approach.