ObjectiveTo obtain the epidemiological characteristics of re-positive cases infected with SARS-CoV-2 in Pudong New Area from March to July 2022, including clinical manifestations, duration of a negative nucleic acid conversion after tested for re-positive, and length of time from the discharge of the initial infection to the most recent re-positivity, so as to provide a scientific basis for the prevention and control of COVID-19. MethodsA questionnaire survey was conducted among the re-positive cases infected with SARS-CoV-2 after discharged from hospital/quarantine facility in Pudong New Area, and descriptive epidemiological methods were used for characteristics analysis. ResultsA total of 2 422 re-positive cases met the inclusive and exclusive criteria, with males accounting for 61.02%. The age distribution mainly fell between 18 and <60 years old, accounting for 62.39%. Clinical manifestations were predominantly asymptomatic (72.15%), followed by cough (12.03%) and sore throat (6.58%). Among the stratified randomized sample of 416 individuals, there were statistically significant differences in symptoms (χ²=262.667, P<0.001), clinical typing (χ²=12.996, P=0.001), and duration of a negative nucleic acid conversion (χ²=142.578, P<0.001) between the initial positive and re-positive instances. Besides, statistically significant differences in symptoms (χ²=13.696, P=0.016) and self-perception of the severity of re-infection (χ²=7.923, P=0.048) between the initial and re-positive cases were observed by different genders. ConclusionAmong re-positive cases, males experienced milder symptoms compared to females, and the self-perception of symptoms during re-positivity is milder than that in the initial positive infection. The length of time for negative nucleic acid conversion during the initial positive period is shorter than that during the re-positive period.

Objective:To evaluate the clinical effect of derotational distal femoral osteotomy (DDFO) combined with medial patellofemoral ligament (MPFL) reconstruction assisted by digital orthopedic technique in the treatment of recurrent patellar dislocation with enlarged femoral anteversion angle (FAA).Methods:TThe clinical data of 18 patients (4 men and 14 women; mean age 22.1±0.7 years; range, 18-26 years) with recurrent patellar dislocation (FAA≥30°) admitted to Digital Orthopedic Technology Clinical Application Center in Tianjin hospital from May 2022 to December 2023 were retrospectively analyzed. The average number of patella dislocations were 3.6±0.4 (range, 2-8 times), with a mean symptom duration of 4.3±0.4 years (range, 2-7 years). According to Dejour classification of femoral trochlea dysplasia, there were 5 cases of type A, 3 cases of type B, 6 cases of type C and 4 cases of type D. All patients underwent 3D CT scanning and digital modeling before operation. Based on the modeling results, personalized osteotomy and orthopedic integration guide were designed and printed to direct intraoperative DDFO and MPFL reconstruction. Radiological parameters, knee function and complications were assessed during follow-up. Knee function assessments included visual analogue scale (VAS), Intemational Knee Documentation Committee Knee Form (IKDC), Kujala, Lysholm and Tegner score. The radiological parameters included FAA, patellar tilt angle (PTA), tibial tuberosity-trochlear groove distance (TT-TG) and caton-deschamps index (CDI).Results:All patients underwent surgery and were followed up for 15.4±2.8 months (range, 12-20 months). Complications occurred in 3 patients, including deep venous thrombosis in 2 cases and wound effusion in 1 case. No other complications such as wound infection, nerve injury, vascular injury, fracture nonunion or patella dislocation were recorded. The VAS score improved from 5.4±0.3 preoperatively to 2.1±0.2 at one year postoperatively. The IKDC score improved from 44.4±2.7 to 79.2±1.9 points. The Kujala score improved from 51.8±2.6 to 86.1±1.6, the Lysholm from 49.8±2.5 to 84.9±1.5, and the Tegner score from 2.2±0.2 to 4.1±0.2. The FAA decreased from 39.7°±1.2° to 14.9°±0.2°, the PTA from 33.1°±2.6° to 12.6°±1.4°, and the TT-TG from 20.2±0.6 to 13.9±0.4 mm. The differences between time of all the above-mentioned parameters were statistically significant ( P<0.05). The CDI remained stable, which changed from 1.03±0.02 preoperatively to 1.07±0.01 one year after operation ( P>0.05). Conclusions:After the application of DDFO combined with MPFL reconstruction assist by personalized osteotomy and orthopedic integrated guide, the patient's knee function and imaging parameters were significantly improved at one-year follow-up. In the treatment of recurrent patellar dislocation with enlarged FAA, good early clinical efficacy could be achieved with this operation.

Objective:To evaluate the clinical effectiveness of high tibial osteotomy (HTO) assisted by digital orthopedic techniques in the treatment of varus knee osteoarthritis secondary to tibial fracture malunion.Methods:The clinical data were retrospectively analyzed of the 16 patients who had been admitted to Clinical Application Center of Digital Orthopedic Technology, Tianjin Hospital for varus knee osteoarthritis secondary to tibial fracture malunion from April 2022 to October 2023. There were 6 men and 10 women, with an age of (56.3±1.6) years and a mean body mass index of (23.8±0.9) kg/m 2. HTO was performed for all the patients using patient-specific instrumentation integrated osteotomy and orthopedic guide which was designed and printed with digital orthopedic techniques. If preoperative imaging indicated symptomatic meniscus injury (tear), intraarticular free body, or intercondylar fossa stenosis in a patient, arthroscopic clearance was first conducted before subsequent performance of HTO at one stage. Clinical effectiveness was evaluated by measuring and comparing hip-knee-ankle angle (HKA), medial proximal tibial angle (MPTA), posterior tibial slope (PTS), lower limb weight-bearing line (WBL) ratio, Western Ontario and McMaster University (WOMAC) osteoarthritis index, visual analogue scale (VAS) pain score and knee range of motion (ROM) before surgery and 12 months after surgery. Results:The operative time was (41.3±2.1) min and intraoperative fluoroscopy was performed only once in all the patients. All the wounds healed by the first stage with no such complications as hinge point fracture, wound infection, vascular injury, nerve injury, delayed union or nonunion of fracture, lower limb deep venous thrombosis, loosening of internal fixation, or plate rupture. The follow-up time for the 16 patients was (16.3±0.7) months. At 12 months after surgery, the HKA (179.5°±0.5°), MPTA (91.7°±0.5°), WBL ratio (61.2%±0.4%), WOMAC osteoarthritis index [(12.8±0.8) points], VAS pain score [(1.8±0.3) points] and knee ROM (121.8°±1.8°) were significantly better than those before surgery [166.6°±1.3°, 81.8°±0.4°, 29.6%±1.0%, (38.4±2.1) points, (4.8±0.3) points, and 110.5°±2.1°] ( P < 0.05). There was no significant difference in PTS between pre-surgery and 12 months after surgery ( P > 0.05). Conclusions:When HTO is used to treat varus knee osteoarthritis secondary to tibial fracture malunion, assistance of digital orthopedic techniques can improve HKA, MPTA, lower limb alignment, and knee ROM to reduce and recover knee function for the patients.

Objective:To evaluate the clinical effect of derotational distal femoral osteotomy (DDFO) combined with medial patellofemoral ligament (MPFL) reconstruction assisted by digital orthopedic technique in the treatment of recurrent patellar dislocation with enlarged femoral anteversion angle (FAA).Methods:TThe clinical data of 18 patients (4 men and 14 women; mean age 22.1±0.7 years; range, 18-26 years) with recurrent patellar dislocation (FAA≥30°) admitted to Digital Orthopedic Technology Clinical Application Center in Tianjin hospital from May 2022 to December 2023 were retrospectively analyzed. The average number of patella dislocations were 3.6±0.4 (range, 2-8 times), with a mean symptom duration of 4.3±0.4 years (range, 2-7 years). According to Dejour classification of femoral trochlea dysplasia, there were 5 cases of type A, 3 cases of type B, 6 cases of type C and 4 cases of type D. All patients underwent 3D CT scanning and digital modeling before operation. Based on the modeling results, personalized osteotomy and orthopedic integration guide were designed and printed to direct intraoperative DDFO and MPFL reconstruction. Radiological parameters, knee function and complications were assessed during follow-up. Knee function assessments included visual analogue scale (VAS), Intemational Knee Documentation Committee Knee Form (IKDC), Kujala, Lysholm and Tegner score. The radiological parameters included FAA, patellar tilt angle (PTA), tibial tuberosity-trochlear groove distance (TT-TG) and caton-deschamps index (CDI).Results:All patients underwent surgery and were followed up for 15.4±2.8 months (range, 12-20 months). Complications occurred in 3 patients, including deep venous thrombosis in 2 cases and wound effusion in 1 case. No other complications such as wound infection, nerve injury, vascular injury, fracture nonunion or patella dislocation were recorded. The VAS score improved from 5.4±0.3 preoperatively to 2.1±0.2 at one year postoperatively. The IKDC score improved from 44.4±2.7 to 79.2±1.9 points. The Kujala score improved from 51.8±2.6 to 86.1±1.6, the Lysholm from 49.8±2.5 to 84.9±1.5, and the Tegner score from 2.2±0.2 to 4.1±0.2. The FAA decreased from 39.7°±1.2° to 14.9°±0.2°, the PTA from 33.1°±2.6° to 12.6°±1.4°, and the TT-TG from 20.2±0.6 to 13.9±0.4 mm. The differences between time of all the above-mentioned parameters were statistically significant ( P<0.05). The CDI remained stable, which changed from 1.03±0.02 preoperatively to 1.07±0.01 one year after operation ( P>0.05). Conclusions:After the application of DDFO combined with MPFL reconstruction assist by personalized osteotomy and orthopedic integrated guide, the patient's knee function and imaging parameters were significantly improved at one-year follow-up. In the treatment of recurrent patellar dislocation with enlarged FAA, good early clinical efficacy could be achieved with this operation.

Objective:To evaluate the clinical effectiveness of high tibial osteotomy (HTO) assisted by digital orthopedic techniques in the treatment of varus knee osteoarthritis secondary to tibial fracture malunion.Methods:The clinical data were retrospectively analyzed of the 16 patients who had been admitted to Clinical Application Center of Digital Orthopedic Technology, Tianjin Hospital for varus knee osteoarthritis secondary to tibial fracture malunion from April 2022 to October 2023. There were 6 men and 10 women, with an age of (56.3±1.6) years and a mean body mass index of (23.8±0.9) kg/m 2. HTO was performed for all the patients using patient-specific instrumentation integrated osteotomy and orthopedic guide which was designed and printed with digital orthopedic techniques. If preoperative imaging indicated symptomatic meniscus injury (tear), intraarticular free body, or intercondylar fossa stenosis in a patient, arthroscopic clearance was first conducted before subsequent performance of HTO at one stage. Clinical effectiveness was evaluated by measuring and comparing hip-knee-ankle angle (HKA), medial proximal tibial angle (MPTA), posterior tibial slope (PTS), lower limb weight-bearing line (WBL) ratio, Western Ontario and McMaster University (WOMAC) osteoarthritis index, visual analogue scale (VAS) pain score and knee range of motion (ROM) before surgery and 12 months after surgery. Results:The operative time was (41.3±2.1) min and intraoperative fluoroscopy was performed only once in all the patients. All the wounds healed by the first stage with no such complications as hinge point fracture, wound infection, vascular injury, nerve injury, delayed union or nonunion of fracture, lower limb deep venous thrombosis, loosening of internal fixation, or plate rupture. The follow-up time for the 16 patients was (16.3±0.7) months. At 12 months after surgery, the HKA (179.5°±0.5°), MPTA (91.7°±0.5°), WBL ratio (61.2%±0.4%), WOMAC osteoarthritis index [(12.8±0.8) points], VAS pain score [(1.8±0.3) points] and knee ROM (121.8°±1.8°) were significantly better than those before surgery [166.6°±1.3°, 81.8°±0.4°, 29.6%±1.0%, (38.4±2.1) points, (4.8±0.3) points, and 110.5°±2.1°] ( P < 0.05). There was no significant difference in PTS between pre-surgery and 12 months after surgery ( P > 0.05). Conclusions:When HTO is used to treat varus knee osteoarthritis secondary to tibial fracture malunion, assistance of digital orthopedic techniques can improve HKA, MPTA, lower limb alignment, and knee ROM to reduce and recover knee function for the patients.