Influence of Patellar Tilt Angle in Merchant View on Postoperative Range of Motion in Posterior Cruciate Ligament-Substituting Fixed-Bearing Total Knee Arthroplasty

BACKGROUND: We investigated whether the patellar tilt angle influences the maximum knee flexion after total knee arthroplasty (TKA) performed by using a posterior cruciate ligament-substituting (PS) fixed-bearing prosthesis in patients with relatively loose or tight flexion gap. METHODS: In this prospective cohort study, we followed up 169 patients for at least 2 years after TKA using PS fixed-bearing prosthesis. The patients were divided into two groups according to the flexion gap value—calculated by subtracting the thickness of the final bearing from the flexion gap measured intraoperatively under 200-cN·m force after patellar reduction and insertion of the final femoral and tibial components—into a relatively tight group (group T; 3–6.5 mm) and a relatively loose group (group L; 7–11 mm). Patellar tilt angles and maximum non–weight-bearing active knee flexion angles were assessed postoperatively. Group T was further divided into subgroup Tn if the patellar tilt angle was < 5° and subgroup Tw if the angle was ≥ 5°. Pearson correlation test was used for the correlation analysis of the flexion gap, patellar tilt angle, and postoperative flexion range. RESULTS: The mean postoperative flexion was 137.3° in group T and 137.5° in group L. The mean patellar tilt angle was 6.5° in group T and 6.9° in group L. In group T, a strong negative correlation (r = −0.78, p < 0.05) was observed between the patellar tilt and postoperative flexion range. However, further analysis revealed that only the subgroup Tw showed a strong negative correlation (r = −0.76, p < 0.05). Significant correlations were not found in the subgroup Tn and group L. CONCLUSIONS: In TKA where a relatively tight flexion gap (≤ 6.5 mm) is created because of concerns about postoperative flexion instability due to a loose flexion gap, the patellar tilt angle should be < 5° for maximal postoperative knee flexion.

Treatment of Wide Gap Non-Unions in Lower Extremities

PURPOSE: To analyze the end results of the treatment for patients with wide gap non-unions of the long bones in the lower extremities. MATERIALS AND METHODS: A total of 62 cases of wide gap unions, with a mean age of 38 years, were included for analysis. Study cohort included six children under the age of seven years. The average size of established bone defect was 7 cm (4-23 cm). Bone defects under 7 cm were treated with plating and various bone grafts, and those over 7 cm were managed with vascularized fibular graft (VFG), distraction-osteogenesis, tibial strut, plating and etc. Two boys with a defect of the whole tibia but with an intact fibula were treated with tibialization of intact fibula and with rotation-plasty of the leg. Their end results were evaluated by the time of bony union in accordance with the treatment of defect size of the long bone as well as their age. RESULTS: Bony unions were obtained for an average period of at least 27 months. Fifty-one cases showed an average leg-length discrepancy of 2.8 cm, and 11 cases showed no leg-length discrepancy. The VFG, distraction-osteogenesis, and tibial cortical-strut graft and plating were the most effective methods for non-unions of wide, long bone defections (>7 cm). The prognosis was more favorable in children, muscular femur, and in cases with tibial defect but intact fí bula. CONCLUSION: Various bone union techniques should be considered carefully, considering the ages of patients and the size of bone defects. Due to severe physical and mental disabilities of patients during the long-treatment period, specialized orthopedic doctors for trauma and mental care were necessary.

Treatment of Wide Gap Non-Unions in Lower Extremities

PURPOSE: To analyze the end results of the treatment for patients with wide gap non-unions of the long bones in the lower extremities. MATERIALS AND METHODS: A total of 62 cases of wide gap unions, with a mean age of 38 years, were included for analysis. Study cohort included six children under the age of seven years. The average size of established bone defect was 7 cm (4-23 cm). Bone defects under 7 cm were treated with plating and various bone grafts, and those over 7 cm were managed with vascularized fibular graft (VFG), distraction-osteogenesis, tibial strut, plating and etc. Two boys with a defect of the whole tibia but with an intact fibula were treated with tibialization of intact fibula and with rotation-plasty of the leg. Their end results were evaluated by the time of bony union in accordance with the treatment of defect size of the long bone as well as their age. RESULTS: Bony unions were obtained for an average period of at least 27 months. Fifty-one cases showed an average leg-length discrepancy of 2.8 cm, and 11 cases showed no leg-length discrepancy. The VFG, distraction-osteogenesis, and tibial cortical-strut graft and plating were the most effective methods for non-unions of wide, long bone defections (>7 cm). The prognosis was more favorable in children, muscular femur, and in cases with tibial defect but intact fí bula. CONCLUSION: Various bone union techniques should be considered carefully, considering the ages of patients and the size of bone defects. Due to severe physical and mental disabilities of patients during the long-treatment period, specialized orthopedic doctors for trauma and mental care were necessary.

Analysis of Impingement between Patella Bone and Bearing Post in Cruciate-Substituting High-Flexion Total Knee Arthroplasty

BACKGROUND: We investigated the causes of impingement between the patella bone and the bearing post during high flexion in cruciate-substituting total knee arthroplasty and proposed a treatment strategy. METHODS: This prospective cohort study included 218 cases that had undergone cruciate-substituting total knee arthroplasty from February 2014 to January 2015; a single surgeon performed the operation using the same method without patellar resurfacing in all patients. RESULTS: In these patients, the occurrence of impingement was determined by performing more than 120° high knee flexion after inserting a bearing perioperatively. The incidence of impingement was significantly associated with bearing design, femoral implant size, patella bone length, and patella inferior pole angle (p < 0.05). The impingement was resolved by resection of the lower articular side of the patella bone. CONCLUSIONS: In the cruciate-substituting high-flexion total knee arthroplasty, impingement between the patella bone and bearing post was more common in patients with mobile bearing, small-size femoral component, and a long patella or a large inferior pole angle. In cases of intraoperative impingement between the patella bone and the bearing post, resection in the lower portion of the patella prevented impingement of the bearing with soft tissue or the patella by widening the space between the patella and the bearing post, which in turn prevented postoperative reduction in range of motion.

Analysis of Impingement between Patella Bone and Bearing Post in Cruciate-Substituting High-Flexion Total Knee Arthroplasty

BACKGROUND: We investigated the causes of impingement between the patella bone and the bearing post during high flexion in cruciate-substituting total knee arthroplasty and proposed a treatment strategy. METHODS: This prospective cohort study included 218 cases that had undergone cruciate-substituting total knee arthroplasty from February 2014 to January 2015; a single surgeon performed the operation using the same method without patellar resurfacing in all patients. RESULTS: In these patients, the occurrence of impingement was determined by performing more than 120° high knee flexion after inserting a bearing perioperatively. The incidence of impingement was significantly associated with bearing design, femoral implant size, patella bone length, and patella inferior pole angle (p < 0.05). The impingement was resolved by resection of the lower articular side of the patella bone. CONCLUSIONS: In the cruciate-substituting high-flexion total knee arthroplasty, impingement between the patella bone and bearing post was more common in patients with mobile bearing, small-size femoral component, and a long patella or a large inferior pole angle. In cases of intraoperative impingement between the patella bone and the bearing post, resection in the lower portion of the patella prevented impingement of the bearing with soft tissue or the patella by widening the space between the patella and the bearing post, which in turn prevented postoperative reduction in range of motion.

Quantitative PCR for Etiologic Diagnosis of Methicillin-Resistant Staphylococcus aureus Pneumonia in Intensive Care Unit / 결핵및호흡기질환

BACKGROUND: Ventilator-associated pneumonia (VAP) requires prompt and appropriate treatment. Since methicillin-resistant Staphylococcus aureus (MRSA) is a frequent pathogen in VAP, rapid identification of it, is pivotal. Our aim was to evaluate the utility of quantitative polymerase chain reaction (qPCR) as a useful method for etiologic diagnoses of MRSA pneumonia. METHODS: We performed qPCR for mecA, S. aureus-specific femA-SA, and S. epidermidis-specific femA-SE genes from bronchoalveolar lavage or bronchial washing samples obtained from clinically-suspected VAP. Molecular identification of MRSA was based on the presence of the mecA and femA-SA gene, with the absence of the femA-SE gene. To compensate for the experimental and clinical conditions, we spiked an internal control in the course of DNA extraction. We estimated number of colony-forming units per mL (CFU/mL) of MRSA samples through a standard curve of a serially-diluted reference MRSA strain. We compared the threshold cycle (Ct) value with the microbiologic results of MRSA. RESULTS: We obtained the mecA gene standard curve, which showed the detection limit of the mecA gene to be 100 fg, which corresponds to a copy number of 30. We chose cut-off Ct values of 27.94 (equivalent to 1x10(4) CFU/mL) and 21.78 (equivalent to 1x10(5) CFU/mL). The sensitivity and specificity of our assay were 88.9% and 88.9% respectively, when compared with quantitative cultures. CONCLUSION: Our results were valuable for diagnosing and identifying pathogens involved in VAP. We believe our modified qPCR is an appropriate tool for the rapid diagnosis of clinical pathogens regarding patients in the intensive care unit.