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Background: Recently, high-flexion PCL-retaining (CR) and -substituting (PS) knee prostheses were designed to allow greater and safer flexion after TKA. However, the advantages of high-flexion TKA over standard design have been debated in terms of early maximal flexion. A recent study reported a high incidence of early loosening of the femoral component related to the deep flexion provided by high-flexion PS TKA. Questions/Purposes: We determined whether high-flexion fixed bearing CR and PS prostheses would provide (1) a better flexion, (2) a better function, and (3) a higher incidence of radiographic loosening than TKA performed using standard fixed bearing CR prostheses in Asian patients. Methods: From a total of 182 patients with primary unilateral TKA, we retrospectively reviewed 137 TKAs: 47 with high-flexion CR, 42 with high-flexion PS, and 48 with standard CR designs. ROM, Knee Society scores, and WOMAC scores were evaluated and compared among the three groups. Radiographically, we assessed radiolucent zones and component loosening. Minimum followup was 5 years (mean, 6.2 years; range, 5-8 years). Results: We found no differences among the three groups in mean maximal flexion (high-flexion CR: 135°; high-flexion PS: 134°; standard CR: 136°), Knee Society scores, and WOMAC scores at last followup. Also, there were no differences among the three groups in terms of radiolucent lines around the prosthesis. No patient in any group had loosening of the femoral component. Conclusions: The high-flexion CR or PS design had no advantages over the standard CR design with respect to ROM, clinical scores, and radiolucent lines around the femoral or tibial component after 5 years' followup. Level of Evidence: Level III, therapeutic study. See Instructions for Authors for a complete description of levels of evidence. [ABSTRACT FROM AUTHOR]

Rationale: A case of traumatic atlanto-axial rotatory subluxation (AARS), dens fracture, rupture of transverse atlantal ligament (TAL), and subaxial spinal cord injury without radiographic abnormality (SCIWORA) of Brown-Sequard syndrome has never been reported in a child., Patient Concerns: A 7-year-old boy presented to hospital with torticollis, neck pain, and limited neck rotation after a seat-belt injury sustained during a car accident. Neurologic examination revealed right-side motor weakness and left-side sensory abnormality, known as Brown-Sequard syndrome., Diagnosis: Radiologic examinations revealed type II AARS (Fielding and Hawkins classification), increased atlanto-dental interval (ADI) of 4.5 mm due to a type 1B TAL rupture (Dickman classification), a displaced transverse dens fracture along with an ossiculum terminale, and an intramedullary hemorrhage on the right side of the spinal cord at C3-4., Interventions: The patient immediately received methylprednisolone, and his motor weakness and sensory abnormality gradually improved. At the same time, the patient underwent initial halter traction for 2 weeks, but he failed to achieve successful reduction and required manual reduction under general anesthesia., Outcomes: At the 7-month follow-up visit, radiologic examinations showed a corrected type II AARS that was well maintained and normalization of the ADI to 2 mm. The reduced transverse dens fracture was well maintained but still not united. All clinical symptoms were significantly improved, except the remaining motor weakness of the right upper extremity., Lessons: To the best of our knowledge, this is the first report of traumatic AARS, dens fracture, TAL rupture, and subaxial SCIWORA of Brown-Sequard syndrome in a child. Appropriate diagnosis and careful treatment strategy are required for successful management of complex cervical injuries in a child., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2021 the Author(s). Published by Wolters Kluwer Health, Inc.)

Study Design: We demonstrated the differentiation of notochordal cells by direct observation using a live automated cell imaging system. We also hypothesized that notochordal cells have characteristics of chondrocyte-like cells., Objective: To determine characteristics of notochordal cells by matrix protein expression and their differentiation using a live automated cell imager., Summary of Background Data: Although notochordal cells are critical to homeostasis of intervertebral disc, their fate has not been extensively studied and there is little evidence of notochordal cells as progenitors., Methods: Notochordal cells purified from rabbit nucleus pulposus were isolated after serial filtration. Notochordal cells in 3-dimensional culture were compared to chondrocyte-like cells by S sulfate incorporation into proteoglycan and reverse transcription polymerase chain reaction for gene expression(collagen II and aggrecan). Notochordal cells in 2-D culture were used for immunocytochemical staining (collagen II, aggrecan, and SOX9) and time-lapsed cell tracking study., Results: Notochordal cells were capable of proteoglycan production at a rate comparable to chondrocyte-like cells (108% +/- 22.6% to chondrocyte-like cells) and expressed collagen II, aggrecan, and SOX9. In time-lapsed cell tracking analysis, notochordal cells were slower in population doubling time than chondrocyte-like cells and differentiated into 3 morphologically distinct cell types: vacuolated cells (area: 2392 +/- 507.1 microm, velocity: 0.09 +/- 0.01 microm/min); giant cells (area: 12678 +/- 1637.0 microm, velocity: 0.08 +/- 0.01 microm/min) which grew rapidly without cell division; polygonal cells (area: 3053 +/- 751.2 microm, 0.14 +/- 0.01 microm/min) morphologically similar to typical differentiation type of chondrocyte-like cells (area: 2671 +/- 235.6 microm, 0.19 +/- 0.01 microm/min). Rarely, notochordal cells formed clusters analogous to that observed in vivo., Conclusion: These studies demonstrate a chondrocyte phenotype of notochordal cells and are the first direct evidence of notochordal cell differentiation, suggesting that they may act as progenitor cells, which has the potential to lead to their use in novel approaches to regeneration of degenerative intervertebral disc.

Although significant differences exist in the methods of treatment and prognoses of septic coxitis and transient synovitis in children complaining of acute hip pain, similar symptoms are present in these two diseases at the early stages, and differential diagnosis is difficult. To differentiate between these two diseases, the authors evaluated the clinical, serologic, and radiologic findings and tried to determine factors that could be used as diagnostic criteria. The authors performed a retrospective study by evaluating medical records, plain hip radiographs, and clinical findings in 97 patients with transient synovitis and 27 patients with septic arthritis. Univariate analysis showed significant differences in body temperature, serum WBC count, and ESR and CRP levels of the two patient groups. Plain radiographs showed a displacement or blurring of periarticular fat pads in all patients with acute septic arthritis, and multivariate regression analysis showed that body temperature >37 degrees C, ESR >20 mm/h, CRP >1 mg/dL, WBC >11,000/mL, and an increased hip joint space of >2 mm were independent multivariate predictors of acute septic arthritis. The authors conclude that the independent multivariate predictors are effective indices for the differential diagnosis of acute septic coxitis and transient synovitis.