Precise Measurement of the Outer Diameters of Antibiotic-Laden Cement Nails Produced by Various Sized Thoracostomy Catheter Molds.

Objectives: At our institution, custom-made antibiotic-laden cement nails (ACNs) fabricated during surgery using a thoracostomy catheter as a mold are commonly used to treat long-bone infection. As the outer diameter of the nails produced has not previously been described, we designed a study to measure the outer diameter of ACNs fashioned using commercially available and commonly utilized thoracostomy catheters of various sizes.

Methods: Six thoracostomy catheters from 2 different manufactures (Argyle PVC Thoracic Catheters; Covidien Ltd and Atrium PVC Thoracic Catheters; Atrium Medical Corporation), ranging from 20 French to 40 French, were utilized in this study. Each catheter was filled with antibiotic-laden cement, and the most proximal segment (largest outer diameter) and most distal segment (smallest outer diameter) were detached for study. Once the cement was cured, the thoracostomy catheters were cut away and the segments were measured using a calibrated digital caliper (Mitutoyo Corp, Aurora, IL). Because the ACNs produced using the technique taper from proximal to distal according to the shape of the thoracostomy catheter design, data were recorded as a maximum and minimum outer diameter for each ACN produced by each of the 6 thoracostomy catheter sizes studied. All measurements were in millimeters and were rounded to the nearest one-tenth of a millimeter.

Results: The ACNs produced using the various sized thoracostomy catheters had segments with outer diameters ranging from 4.2 mm to 11.2 mm. Both brands of catheters produced nails with similar distal diameters. Specifically, the mean distal diameter measurements were 4.2 mm for a 20 French catheter, 5.5 mm for a 24 French catheter, 6.6 mm for a 28 French catheter, 7.7 mm for a 32 French catheter, 8.4 mm for a 36 French catheter, and 9.9 mm for a 40 French catheter. The Argyle brand catheters produced nails with proximal diameters that increased with the catheter's size, from 7.1 mm for a 20 French catheter to 11.2 mm for a 40 French catheter. The Atrium brand catheters produced nails with a much tighter range of proximal diameters ranging from 9.4 mm to 11.1 mm.

Conclusions: Thoracostomy catheters are commonly utilized to produce ACNs. The results of our study confirm that the fabricated nails taper in diameter from proximal to distal. Knowledge of the specific dimensions of the ACN produced by each size thoracostomy catheter will aid the orthopaedic surgeon in selecting the right size based on the diameter of the medullary canal being treated.