The Use of a Novel On-bone Femoral Spacer Molding Device for Reducing Femoral Spacer Complications in Periprosthetic Total Knee Infection: Preliminary Results.

Background: The complications of mobile cement spacer are common. To address these issues, a novel on-bone femoral molding device (FMD) has been developed to enhance stability between the spacer-bone. This study investigated the clinical outcomes and complications associated with this novel FMD. Methods: The FMD was developed using a reverse engineering program with the on-bone molding concept. Five knees of 4 patients were examined. The bone status, ambulatory ability, knee range of motion, and femoral spacer complications were followed up until 3 months after the second-stage surgery. Results: The infection was successfully treated in all patients. The interim period was 21.6 ± 4.5 weeks. The range of motion measured before the first surgery, before the second surgery, and 3 months after the second surgery was 104.2 ± 43.1, 105.8 ± 20.0, and 124.0 ± 18.5 degrees, respectively. No femoral spacer complications were observed. One knee joint subluxation and 1 minor tibial spacer fracture occurred. Conclusions: Newly developed FMD appears safe during initial proof-of-concept in patients with stage 1 to 2B bone loss. It prevents femoral spacer complications in a specific bone defect type without causing additional bone loss and facilitates range of motion during the interim period. Precise gap assessment and appropriate tibial cement spacer thickness could prevent knee dislocation.

Effectiveness of laser welding in cerclage wiring fixation: a biomechanical study.

Introduction: Cerclage wiring is a common orthopedic procedure for fracture fixation. However, previous studies reported wiring-related perioperative complications, such as wire loosening or breakage, with an incidence rate of up to 77%. Recently, the use of laser welding on medical implants was introduced to connect biomedical materials. This study used laser technology to weld between wires after conventional cerclage fixation. We hypothesized that the laser welding could significantly increase the biomechanical properties of cerclage wiring fixation. Materials and methods: Twenty-five wiring models underwent biomechanical tests in five cerclage wiring configurations (five models per group), namely, (1) single loop, (2) single loop with laser welding, (3) double loop, (4) double loop with one-side laser welding, and (5) double loop with two-side laser welding. Characteristics such as load to failure, mode of failure, and wiring failure were compared between groups. The biocompatibility for a 316L stainless steel wire with laser welding was evaluated via an in vitro hemolysis test. Results: Mean load to failure of the double loop with one-side and two-side laser welding groups were 3,596 ± 346 N and 3,667 ± 240 N, which were significantly higher than for the double-loop group (2,919 ± 717 N) (p = 0.012 and p = 0.044, respectively). Conversely, no significant difference was shown in the comparison of the mean load to failure between the single loop and the single loop with laser-welded cerclage wire (1,251 ± 72 N, 1,352 ± 122 N, and p = 0.12). Untwisted wire and wire breakage were the most common mode of failure. All welding specimens revealed non-hemolytic effects from in vitro hemolysis test. Conclusion: Laser welding on cerclage wiring significantly increases the biomechanical property of double cerclage wire fixation. However, further biocompatibility tests and clinical studies are still recommended.

Effectiveness of prophylactic double-looped wiring in cementless Hip arthroplasty: A biomechanical study in osteoporotic bone model using impaction simulation system.

BACKGROUND: Periprosthetic femoral fracture (PFF) is well-known complication in cementless hip arthroplasty (HA), especially in the elderly with osteoporosis. To prevent intraoperative PFFs during HA, prophylactic cerclage wiring on the calcar area during femoral broaching and implant insertion is recommended. However, biomechanical data on the benefits of cerclage wiring in osteoporotic bone during impaction are limited and controversial. This study aimed to assess the efficacy of prophylactic double-looped cerclage wiring (PDLCW) during femoral broaching in the osteoporotic bone model with an impaction simulation system. METHODS: Fifteen osteoporotic femur models were prepared and allocated to three groups; control group (no cerclage), PW group (received PDLCW), and CC+PW group (prepared as having calcar crack and received PDLCW). All femurs were broached under impaction force that sequentially increased until the visible fracture or calcar crack propagation was visible. The primary outcomes were mallet impaction force (MIF-CF) and mallet velocity (MV-CF) at the time of calcar fracture. The secondary outcomes were calcar fracture pattern and subsidence during calcar fracture (S-CF). RESULTS: PW group showed a significant increase in average MIF-CF, by 40.4% and 120.2% (p<0.001) compared to the control and CC+PW groups, respectively. The average MV-CF in PW group was also significantly greater, 13.1% and 64.6% (p<0.001), compared to the control and CC+PW groups, respectively. Control group revealed significantly greater incidence of complete calcar fracture (60% vs. 0% vs. 0%, p = 0.024), and the highest S-CF compared to those in the PW and CC+PW groups (10.6 ±â€¯6.0 mm, 6.7 ±â€¯4.4 mm, and 1.3 ±â€¯2.0 mm, p = 0.020). CONCLUSIONS: This study showed that PDLCW significantly improved hoop stress resistance by increasing the calcar fracture threshold related to mallet impaction, decreasing the risk of complete calcar fracture.