An Evaluation of the Bacterial Adherence to Casting Materials.

INTRODUCTION:  The purpose of this study was to evaluate bacterial adherence to common casting materials including plaster of Paris (plaster), fiberglass, three-dimensional (3D) printed plastic, and silicone-coated 3D printed plastic. METHODS: The minimal inhibitory concentration of a phosphate-free detergent (Palmolive) needed to achieve total bacterial kill off was determined. 3D printed polylactic acid plastic samples were coated with silicone. Plaster, fiberglass, plastic, and silicone-coated plastic samples were inoculated with Staphylococcus aureus. After bacterial inoculation, scanning electron microscopy of the samples was performed to visualize bacterial adherence to the materials' surface. Using either sterile water or a 5% detergent solution, the materials were subjected to washings. Each material was run in 30 replicates: 6 without washing, 6 with sterile water for 1 minute, 6 with detergent for 1 minute, 6 with sterile water for 3 minutes, and 6 with detergent for 3 minutes. The replicates that did not undergo a washing trial represented the initial bacterial inoculation. Samples were then rinsed and sonicated in polysorbate to isolate the remaining adherent bacteria on the materials' surface. The sonicated solutions were plated, incubated, and counted for quantification of colony forming units (CFU) of bacteria. This protocol was repeated for a total of four trials. RESULTS: During inoculation, there were significantly less bacteria that adhered to silicone-coated 3D printed plastic (58879 CFU) compared to plastic (217479 CFU), plaster (140063 CFU), and fiberglass (550546 CFU). Silicone coating showed further superiority. Silicone-coated 3D printed plastic was able to be decontaminated as demonstrated by significantly fewer remaining bacteria (9.3%) on its surface after being washed with a 5% detergent solution (1797 CFU) compared to sterile water (19321 CFU). The mean remaining bacteria on silicone-coated 3D printed plastic was significantly less than that remaining on all other materials when washed with either sterile water or a detergent solution for both durations of 1 minute and 3 minutes. CONCLUSIONS: The current study demonstrates that significantly less bacteria adhere to the surface of 3D printed plastic with silicone coating showing added protection and that this material can be decontaminated to a greater degree with washing than conventional casting materials. These results provide evidence that 3D printed casts can be washed and successfully decontaminated during a patient's period of immobilization, which is advantageous especially during an infectious crisis such as the coronavirus disease 2019 (COVID-19) pandemic.

The Accuracy of 3D Printed Carpal Bones Generated from Cadaveric Specimens.

BACKGROUND: Computer assisted three-dimensional (3D) printing of anatomic models using advanced imaging has wide applications within orthopaedics. The purpose of this study is to evaluate the 3D printing accuracy of carpal bones. METHODS: Seven cadaveric wrists underwent CT scanning, after which select carpal bones (scaphoid, capitate, lunate, and trapezium) were dissected in toto. Dimensions including length, circumference, and volume were measured directly from the cadaver bones. The CT images were converted into 3D printable stereolithography (STL) files. The STL files were converted into solid prints using a commercially available 3D printer. The 3D printed models' dimensions were measured and compared to those of the cadaver bones. A paired t-test was performed to determine if a statistically significant difference existed between the mean measurements of the cadavers and 3D printed models. The intraclass correlation coefficients (ICC) between the two groups were calculated to measure the degree of agreement. RESULTS: On average, the length and circumference of the 3D printed models were within 2.3 mm and 2.2 mm, respectively, of the cadaveric bones. There was a larger discrepancy in the volume measured, which on average was within 0.65 cc (15.9%) of the cadaveric bones. These differences were not statistically significant (P > 0.05). There was strong agreement between all measurements except the capitate's length and lunate's volume. CONCLUSION: 3D printing can add value to patient care and improve outcomes. This study demonstrates that 3D printing can both accurately and reproducibly fabricate boney models that closely resemble the corresponding cadaveric anatomy.

Risk of Infection in Trigger Finger Release Surgery Following Corticosteroid Injection.

PURPOSE: To determine the risk for infection in trigger finger release surgery after preoperative corticosteroid injection. METHODS: We retrospectively evaluated all patients undergoing trigger finger release by 16 surgeons over a 2-year period. Data collected included demographic information, medical comorbidities, trigger finger(s) operated on, presence of a prior corticosteroid injection, date of most recent corticosteroid injection, postoperative signs of infection, and need for surgery owing to deep infection. Superficial infection was defined per Centers for Disease Control criteria. Deep infection was defined as the need for surgery related to a surgical site infection. RESULTS: In this cohort of 2,480 fingers in 1,857 patients undergoing trigger release surgery, 53 (2.1%) developed an infection (41 superficial [1.7%] and 12 deep [0.5%]). Before surgery, 1,137 fingers had no corticosteroid injection. These patients developed 1 deep (0.1%) and 17 superficial (1.5%) infections. In contrast, 1,343 fingers had been given a corticosteroid injection before surgery. These patients developed 11 deep (0.8%) and 24 superficial (1.8%) infections. Median time from corticosteroid injection to trigger release surgery was shorter for fingers that developed a deep infection (63 days) compared with those that developed no infection (183 days). The risk for developing a deep infection in patients who were operated on within 90 days of an injection (8 infections in 395 fingers) was increased compared with patients who were operated on greater than 90 days after an injection (3 infections in 948 fingers). CONCLUSIONS: Preoperative corticosteroid injections are associated with a small but statistically significantly increased rate of deep infection after trigger finger release surgery. The risk for postoperative deep infection seems to be time dependent and greater when injections are performed within 90 days of surgery, especially in the 31- to 90-day postinjection period. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Union Rates and Complications After Thumb Metacarpophalangeal Fusion.

Background: Fusion of the thumb metacarpophalangeal joint (MPJ) can be performed using tension band wiring (TBW) or plate and screw (PS) fixation. This study evaluated results and complications using these techniques. Methods: A retrospective review of patients who underwent thumb MPJ fusion at our institution from 2010 to 2016 was performed. Patients with >1 year follow-up were included. Demographic information, indication for fusion, time to fusion, and complications were collected. Final radiographs were examined and alignment measured. Results: There were 56 thumbs in 53 patients (42 women and 11 men) including 12 TBW and 44 PS. The mean age was 60.9 years, and follow-up was 32.4 months. Twenty-eight of 44 plates were nonlocking, and 16 were locking. Of the locking plates, 7 of 26 used all locking screws, and 9 of 26 had a combination of locked and nonlocked screws. The mean flexion angle for TBW was 16.5° and PS was 12.8°. The mean coronal angle for TBW patients was 4.0° ulnar and PS was 2.5° ulnar. The overall union rate was 95%. There were 12 complications, 9 in the PS group. The TBW complications were painful hardware requiring removal. Eight complications in the PS group occurred in patients with locked plates. Five of the delayed or nonunions occurred in patients with locked plates and 4 of these were in plates with all screws locked. Conclusion: Complications using PS or TBW are not infrequent. Alignment with both techniques is similar, but use of locked plates specifically increases the rate of delayed or nonunions. We do not recommend routine use of locked plates for fusion of the thumb MPJ.

Arterial Injury in the Upper Extremity: Evaluation, Strategies, and Anticoagulation Management.

Trauma to the upper extremity can present with an associated arterial injury. After patient stabilization, thorough assessment with physical examination and various imaging modalities allows accurate diagnosis of the specific arterial injury. After diagnosis, efficient treatment is necessary to allow limb salvage. Treatment options include ligation, primary repair, graft reconstruction, endovascular repair, and amputation. The final treatment rendered is frequently dependent on injury location and mechanism. With any of the treatment options, complications may occur, including thrombosis. Currently, no validated anticoagulation protocol has been established for managing arterial injuries in the upper extremity.