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This article explores the positioning of the patellar component in total knee arthroplasty (TKA) and its impact on patellar tracking. It reviews existing literature and presents the findings of a cadaver study on the effects of different implant locations. The study suggests that medially placed, optimally sized patellar components result in the best tracking within the femoral groove. However, there is no consensus on the appropriate degree of medialization, and individualized positioning may be necessary based on the patient's anatomy. The article emphasizes the need for further research to validate the optimal placement of the patellar implant. [Extracted from the article]

We present a case series with the objective of identifying risk factors for nonunion after open and arthroscopic primary ankle arthrodesis. Eighty-seven patients who underwent primary ankle arthrodesis and met inclusion criteria were divided into open (N = 46) and arthroscopic (N = 41) groups. Patient and operative characteristics were retrospectively analyzed as possible risk factors for nonunion within each technique. The nonunion rate was 11% in the open and 12% in the arthroscopic group. Obesity, smoking, and ASA class 3 were highly prevalent in both groups. In the arthroscopic group, a remote history of infection and the use of headed screws had notably higher risk of nonunion, though not statistically significant. In the open group, use of bone graft trended toward lower risk of nonunion, though also not statistically significant. The results of this study demonstrated, nonunion rates are comparable between open and arthroscopic ankle arthrodesis in high-risk patients. For patients with a remote history of infection, open ankle arthrodesis may be preferable, and bone graft importance may vary with open versus arthroscopic technique. Level of evidence: III. [ABSTRACT FROM AUTHOR]

Plastic waste poses an ecological challenge1–3 and enzymatic degradation offers one, potentially green and scalable, route for polyesters waste recycling4. Poly(ethylene terephthalate) (PET) accounts for 12% of global solid waste5, and a circular carbon economy for PET is theoretically attainable through rapid enzymatic depolymerization followed by repolymerization or conversion/valorization into other products6–10. Application of PET hydrolases, however, has been hampered by their lack of robustness to pH and temperature ranges, slow reaction rates and inability to directly use untreated postconsumer plastics11. Here, we use a structure-based, machine learning algorithm to engineer a robust and active PET hydrolase. Our mutant and scaffold combination (FAST-PETase: functional, active, stable and tolerant PETase) contains five mutations compared to wild-type PETase (N233K/R224Q/S121E from prediction and D186H/R280A from scaffold) and shows superior PET-hydrolytic activity relative to both wild-type and engineered alternatives12 between 30 and 50 °C and a range of pH levels. We demonstrate that untreated, postconsumer-PET from 51 different thermoformed products can all be almost completely degraded by FAST-PETase in 1 week. FAST-PETase can also depolymerize untreated, amorphous portions of a commercial water bottle and an entire thermally pretreated water bottle at 50 ºC. Finally, we demonstrate a closed-loop PET recycling process by using FAST-PETase and resynthesizing PET from the recovered monomers. Collectively, our results demonstrate a viable route for enzymatic plastic recycling at the industrial scale.Untreated, postconsumer-PET from 51 different thermoformed products can all be almost completely degraded by FAST-PETase in 1 week and PET can be resynthesized from the recovered monomers, demonstrating recycling at the industrial scale. [ABSTRACT FROM AUTHOR]

Background: Arthrodesis is considered the gold standard for end-stage ankle arthritis in patients who fail conservative management. Achieving union is paramount while minimizing complications. An essential item for successful union is preparation of the articular surface. Our study aims to evaluate the difference in joint preparation between direct lateral and dual mini-open approaches. Materials and Methods: Ten below knee fresh-frozen specimens were used for this study. Five were prepared through lateral approach, and five using dual mini-incisions. After preparation, all ankles were dissected and images of tibial plafond and talar articular surfaces were taken. Surface areas of articulating facets and unprepared cartilage of talus, distal tibia, and distal fibula were measured and analyzed. Results: A greater amount of total surface area was prepared with the mini-open approach in comparison to the transfibular approach. Percentage of prepared surface area of total articulating surface (including talus and tibia/fibula), talus, tibia, and fibula with the transfibular approach were 76.9%, 77.7%, and 75%, respectively. Percentages were 90.9%, 92.9%, and 88.6% with the mini-open approach. When excluding medial gutter, there was no significant difference between techniques (83.94% vs. 90.85%, p = 0.1412). Conclusion: Joint preparation with the mini-open approach is equally efficacious as the transfibular approach for the tibiotalar joint. The mini-open approach does provide superior preparation of the medial gutter and inferior tibial surface which may help to increase union rates and decreased complications. Level of Evidence: V. [ABSTRACT FROM AUTHOR]

Introduction: Tibiocalcaneal (TC) arthrodesis is commonly performed in patients with severe hindfoot disease. These include severe Charcot deformities, ankle malformations, chronic osteomyelitis (COM), and avascular necrosis (AVN). The talar vascular becomes disrupted to the point that the bone can no longer be salvaged. The procedure involves performing a talectomy and fusing the tibia to the calcaneus. This helps in preserving the remaining hindfoot anatomy, while allowing the patient to regain function and mobility. Our study highlights certain risk factors that influence the rate of postoperative complication after tibiocalcaneal surgery. Materials and Methods: We retrospectively reviewed the charts of 18 patients from a single institution who underwent tibiocalcaneal between the years of 2011 and 2019. Preoperative diagnoses, comorbidities, and post-operative outcomes were noted among all patients. Then, the rates of non-union, below-knee amputations, revision surgeries, postoperative infections, and hardware failure were recorded. These data were then analyzed to determine which preoperative and perioperative factors affected postoperative outcomes for patients after tibiocalcaneal arthrodesis surgery. Results: Nonunion was the most commonly reported complication in this series. Eight of the eighteen patients were documented to have nonunion including three patients with stable pseudarthrosis. Diabetic patients had a slightly higher incidence of nonunion (4 of 7 patients) compared to those without diabetes (4 of 11 patients). Of the nine patients diagnosed with Charcot arthropathy, five had nonunion. Three of the five individuals with a BMI ranging from 25 to 30, and four of the six individuals with a BMI of greater than 30 had a nonunion. Infection was a post-operative complication for four of the eighteen patients. Two of the four patients had multiple comorbidities in addition to chronic infections in the joint which were recurrent after surgery. Conclusion: In conclusion, TC arthrodesis provides a viable option for high-risk patients with complicated ankle pathology who have not had successful outcomes from previous treatment. It is not without complications considering the comorbidities the patients present with before requiring this procedure. Further studies are necessary to validate the trends of outcomes and comorbidities of patients with TC arthrodesis. [ABSTRACT FROM AUTHOR]

Background: The use of ultrasound for peripheral nerve blocks has proven extremely useful for improving the accuracy and efficacy of many regional anesthetic techniques. There remain a few nerve blocks which have lagged behind in employing the assistance of ultrasound consistently, one of which is the ankle block. This block is commonly utilized for either surgical anesthesia or post-operative analgesia for a variety of foot and ankle procedures. The objective of this study was to compare the accuracy of traditional anatomical landmark-guided technique with an ultrasound-guided approach for ankle block by assessing the spread of injectate along the posterior tibial nerve (PTN) in cadaver models. Materials and Methods: Ten below-knee cadaver specimens were used for this study. Five were randomly chosen to undergo anatomical landmark-guided PTN blocks, and five were selected for ultrasound-guided PTN blocks. The anatomical landmark technique was performed by identifying the medial malleolus and Achilles tendon and inserting the needle (4 cm long, 21G Braun® Stimuplex) at the midpoint of the two structures, aiming toward the medial malleolus and advancing until bone was contacted. The ultrasound technique was performed with a linear probe identifying the medial malleolus and the PTN, with the needle subsequently advanced in-plane with a posterior to anterior trajectory until the tip was adjacent to the nerve. Each specimen was injected with 2 mL of acrylic dye. All the specimens were dissected following injection to determine which nerves had been successfully coated with dye. Results: The PTN was successfully coated with dye in all five (100%) ultrasound-guided blocks. In the anatomical landmark group, two (40%) PTN were successfully coated with dye. Of the three unsuccessful attempts, two specimens were noted to have dye injected posterior to the PTN; dye was injected into the flexor digitorum longus tendon in one. Conclusion: The base of evidence has dramatically increased in recent years in support of the use of ultrasound in regional anesthesia. This study substantiates the superiority of ultrasound guidance for ankle block by demonstrating a 100% success rate of delivering a simulated nerve block to the correct anatomic location. [ABSTRACT FROM AUTHOR]

Background: Arthrodesis is considered the gold standard for end-stage ankle arthritis in patients who fail conservative management. Achieving union is paramount while minimizing complications. An essential item for successful union is preparation of the articular surface. Our study aims to evaluate the difference in joint preparation between direct lateral and dual mini-open approaches., Materials and Methods: Ten below knee fresh-frozen specimens were used for this study. Five were prepared through lateral approach, and five using dual mini-incisions. After preparation, all ankles were dissected and images of tibial plafond and talar articular surfaces were taken. Surface areas of articulating facets and unprepared cartilage of talus, distal tibia, and distal fibula were measured and analyzed., Results: A greater amount of total surface area was prepared with the mini-open approach in comparison to the transfibular approach. Percentage of prepared surface area of total articulating surface (including talus and tibia/fibula), talus, tibia, and fibula with the transfibular approach were 76.9%, 77.7%, and 75%, respectively. Percentages were 90.9%, 92.9%, and 88.6% with the mini-open approach. When excluding medial gutter, there was no significant difference between techniques (83.94% vs. 90.85%, p  = 0.1412)., Conclusion: Joint preparation with the mini-open approach is equally efficacious as the transfibular approach for the tibiotalar joint. The mini-open approach does provide superior preparation of the medial gutter and inferior tibial surface which may help to increase union rates and decreased complications., Level of Evidence: V., Competing Interests: Conflict of interestNo benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article., (© Indian Orthopaedics Association 2020.)