Tobacco Use Is Associated with More Severe Adverse Outcomes Than Morbid Obesity after Aseptic Revision TKA.

The association of morbid obesity with increased revision total knee arthroplasty (rTKA) complications is potentially confounded by concurrent risk factors. This study was performed to evaluate whether morbid obesity was more strongly associated with adverse aseptic rTKA outcomes than diabetes or tobacco use history-when present as a solitary major risk factor. Demographic characteristics, surgical indications, and adverse outcomes (reoperation, revision, infection, and amputation) were compared between 270 index aseptic rTKA performed for patients with morbid obesity (n = 73), diabetes (n = 72), or tobacco use (n = 125) and 239 "healthy" controls without these risk factors at a mean 75.7 (range: 24-111) months. There was no difference in 2-year reoperation rate (17.8 vs. 17.6%, p = 1.0) or component revision rate (8.2 vs. 8.4%) between morbidly obese and healthy patients. However, higher reoperation rates were noted in patients with diabetes (p = 0.02) and tobacco use history (p < 0.01), including higher infection (p < 0.05) and above knee amputation (p < 0.01) rates in patients with tobacco use history. Multivariate analysis retained an independent association between smoking history and amputation risk (odds ratio: 7.4, 95% confidence interval: 1.7-55.2, p < 0.01). Morbid obesity was not associated with an increased risk of reoperation or component revision compared with healthy patients undergoing aseptic revision. Tobacco use was associated with increased reoperation and above knee amputation. Additional study will be beneficial to determine whether risk reduction efforts are effective in mitigating postoperative complication risks.

Sterility of 3D-Printed Orthopedic Implants Using Fused Deposition Modeling.

The use of 3-dimensional (3D) printing in orthopedics is developing rapidly and impacting the areas of preoperative planning, surgical guides, and simulation. As this technology continues to improve, the greatest impact of 3D printing may be in low- and middle-income countries where surgical items are in short supply. This study investigated sterility of 3D-printed ankle fracture fixation plates and cortical screws. The hypothesis was that the process of heated extrusion in fused deposition modeling printing would create sterile prints in a timely fashion that would not require postproduction sterilization. A free computer-assisted design program was used to design the implant models. One control group and 8 study groups were printed. Print construct, orientation, size, and postproduction sterilization differed among the groups. Sterility was assessed using thioglycollate broth cultures at 24 hours, 48 hours, and 7 days. Positive growth was speciated for aerobic and anaerobic bacteria. Print time and failed prints were recorded. Control samples were 100% positive for bacterial growth. All test samples remained sterile at all time points (100%). Speciation of control samples was obtained, and Staphylococcus was the most common species. Print times varied; however, no print time exceeded 6.75 minutes. Eighteen prints (17%) failed in the printing process. These findings demonstrate an intrinsic sterilization process associated with fused deposition modeling 3D printing and indicate the feasibility of 3D-printed surgical implants and equipment for orthopedic applications. With future research, 3D-printed implants may be a treatment modality to assist orthopedic surgeons in low- and middle-income countries. [Orthopedics. 2020; 43(1): 46-51.].