Antibiotic coated hinged threaded rods in the treatment of infected nonunions and intramedullary long bone infections

INTRODUCTION

Local delivery of high dose antibiotics in the form of antibiotic impregnated polymethyl methacrylate (PMMA) cement beads or coated rods is commonly used in the management of long bone infections. The downsides of antibiotic cement beads for intramedullary long bone infections are associated with difficulty in removal from the medullary canal, bead breakage, and lack of stability. Antibiotic cement-coated smooth flexible guide wires, rods and nails can have complications such as delamination or debonding of the cement. In addition, the current techniques for cement rod insertion have a risk of iatrogenic joint contamination. To improve upon this technique and decrease potential complications, we propose the use of an antibiotic cement-coated hinged threaded rod as a temporary intramedullary spacer. This technique utilizes both an antegrade and retrograde insertion of the threaded rod into the medullary canal through the bony defect site with connection at the hinge to treat intramedullary long bone infections and infected nonunions.

MATERIAL AND METHODS

A total of 40 patients were included in the study. The details in making the cement rod were well documented. The shape of cement rod and the integrity of the cement at the time of rod insertion and rod removal were compared to identify any cement debonding or delamination. Potential postoperative complications including iatrogenic joint infection, displacement or breakage of the threaded cement rods, and fracture displacement were all carefully documented. The preliminary biological effect of the initial debridement and antibiotic cement rod placement was determined using the negative conversion rate of intraoperative cultures.

RESULTS

A single antibiotic coated threaded rod was inserted in 18 cases. Two separate antibiotic coated threaded rods were inserted and connected via hinge in 22 cases. There were zero cases of rod breakage and no secondary loss of reduction from antibiotic rod placement to the definitive staged operation. There were zero iatrogenic joint infections. There were zero cases of cement debonding or delamination from the rod. The conversion rate to a negative culture after initial debridement and antibiotic rod placement was 85% (34/40 cases).

CONCLUSIONS

The use of an antibiotic coated cement threaded rod with a hinge as an intramedullary spacer provides the benefits of local antibiotic delivery, offers improved construct stability, makes implant removal easier without delamination of the cement mantle, and utilizes the versatility of a hinge to prevent violation of native joints when treating infected nonunions and intramedullary long bone infections.

Custom-made antibiotic cement nails: a comparative study of different fabrication techniques

INTRODUCTION

The management of intramedullary long bone infections remains a challenge. Placement of antibiotic cement nails is a useful adjuvant to the antibiotic treatment of osteomyelitis. However, fabrication of antibiotic cement nails can be arduous. The purpose of this article is to introduce an easy and reproducible technique for the fabrication of antibiotics cement nails.

MATERIALS AND METHODS

We compared the time required to peel the chest tube off the 6 antibiotic cement nail using 2 different cement-cooling techniques and the addition of mineral oil in the chest tube. Additionally, we evaluated the optimal time to cut the chest tube (before and after cement hardening), consistency of nail's diameter, and the roughness of its surface. Cooling and peeling times were measured and failure was defined as a working time (from cement mixing to have a usable antibiotic cement nail) that exceeded 1 h.

RESULTS

When the antibiotic cement nail was left to cool by convection (i.e. air-cooling), we failed to peel the plastic off the cement nail. When the chest tube was cut after conductive cooling (i.e. cold water-cooled), the cooling time was 10 min and the peeling time was 30 min without the use of mineral oil; the addition of mineral oil reduced peeling time to 7.5 min. Following peeling, residual adherent plastic pieces were found along the entire surface of the nail when no mineral oil was used. This was rarely seen when mineral oil was utilized to coat the inner layer of the chest tube.

CONCLUSION

Conductively cooling of the cement nail (in cold water) and pre-lubricating the chest tube with mineral oil are 2 tricks that render fabrication of antibiotic nail more efficient, reliable, and practical.