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The valgus cut angle is the angle between mechanical and anatomical axis of the femur (FMA and FAA), and femoral condyle rotation is the angle between surgical trans-epicondylar axis and posterior condylar axis (sTEA and PCA). We used these indexes in total knee arthroplasty.
JOURNAL OF MEDICAL RESEARCH RESULTS OF TOTAL KNEE ARTHROPLASTY USING THE FEMORAL CONDYLE ROTATIONAL AND THE VALGUS CUT ANGLE Huy Phuong Nguyen, Dung Tran Trung Hanoi Medical University We conducted a prospective study of 48 patients with 54 diagnoses of osteoarthritis of the knee All patients were underwent knee MRI and long leg radiograph pre-operatively The valgus cut angle is the angle between mechanical and anatomical axis of the femur (FMA and FAA), and femoral condyle rotation is the angle between surgical trans-epicondylar axis and posterior condylar axis (sTEA and PCA) We used these indexes in total knee arthroplasty The results of total knee arthroplasty, based on imaging criteria and KSS scale (KS and KFS) following up post-surgery to 15 months, are as follows: the mean of valgus cut and femoral condyle rotational angle were 7.47º ± 1.25º and 3.52º ± 1.86º, respectively There were no differences between men and women The mean of mechanical axis post-surgery was 1.22º ± 0.45º (0.02º - 5.05º) The mean of pre-operative and post-operative KS scoring and KFS scoring were 32.74 ± 10.36 and 88.8 ± 9.3, 39.35 ± 12.36 and 82.77 ± 15.63, respectively Applying femoral condyle rotational and valgus cut angles as indexes for surgery can improve the precision and outcomes of total knee arthroplasty Keywords: femoral condyle rotational, valgus cut angle, knee osteoarthritis, total knee arthroplasty I INTRODUCTION Osteoarthritis of the knee is a common disease leading to disability among the elderly According to the epidemiology studies, about 13 % of people aged 60 and above report having symptoms of knee osteoarthritis [1] Total knee arthroplasty (TKA) is a surgery in which damaged articular cartilage is removed and replaced by artificial components Restoring the lower limb axis and correctly placing the artificial components are basic requirements of total knee arthroplasty There are many Corresponding author: Nguyen Huy Phuong, Department of Surgery, Hanoi Medical University Email: drhuyphuong@gmail.com Received: 27/11/2018 Accepted: 12/03/2019 JMR 118 E4 (2) - 2019 techniques which are used to determine the femoral condyle rotation, however they are mainly based on landmarks of femoral condyle [2] The anatomical landmarks which are normally used to achieve correct rotational alignment of the femoral component during surgery are the posterior condylar axis (PCA), anteroposterior axis (AP axis), and transepicondylar axis (TEA) The surgical transepicondylar axis (sTEA) has been evaluated as an axis that reflects exactly the knee flexion axis and perpendicular to mechanical axis of femur [3] Studies in Europe and America have shown that the line connecting posterior edges of femoral condyle rotates about 3º in comparison with sTEA which means that the femoral rotation is 3º to the horizontal knee axis [4; 5] 37 JOURNAL OF MEDICAL RESEARCH To identify the femoral condyle rotation and valgus cut angle in knee osteoarthritic patients who have indicated total knee arthroplasty To evaluate the results of total knee arthroplasty which was applied femoral condyle rotational and valgus cut angle technique II METHODS Figure Diagram demonstrating the TEA, APA and PCA, axes The 3º femoral rotation angle is currently being used in Vietnam However, several studies in Asian populations have showed that this angle ranges from 1.7º to 9.7º [6] Moreover, the recovery of the lower limb axis post-surgery can be better when the axis is close to 0º It also depends on the distal femoral cut and valgus cut angle, which are created by mechanical axis and anatomical axis of the femur (figure 2) This angle is also different between patients Materials 1.1 Subject Inclusion criteria - The osteoarthritis patients have indications for total knee arthroplasty - The patients underwent MRI (Magnetic resonance imaging) and long leg radiograph before surgery - The patient who participated in the research Exclusion criteria - Osteoarthritis patients who not have indications or who have contraindications to total knee arthroplasty - Patients who had various axes cannot be identified in MRI and long leg radiograph - Patients who had bone fractures or general surgical interventions of the knee before Sample size We used total population sampling type (purposive sampling), recruiting 48 patients with 54 osteoarthritic knees in which total knee arthroplasty surgery was appropriate Figure The anatomical and mechanical axis of the femur Therefore, we conducted this research on Vietnamese patients with the following purposes: 38 1.2 Study Design Prospective cross-sectional study 1.3 Place Department of Orthopedic and Trauma and Department of Radiology in Saint Paul Hospital JMR 118 E4 (2) - 2019 JOURNAL OF MEDICAL RESEARCH and Hanoi Medical University Hospital 1.4 Duration From July, 2016 to May, 2018 1.5 Variable research - Age and gender; the femoral rotated angle (sTEA and PCA) - The valgus cut angle (FMA - Femoral mechanical-anatomical angle, and FAA Femoral anteversion angle); the mechanical axis of lower limb post-surgery - KSS score (including KS - Knee score, and KFS - Knee functional score) before and after surgery Methods MRI scanning system 1.5 Tesla which was made in Florida, USA, in November, 2009, serial 037255, thin slice cut 1mm, 256 slices and X-rays machine Simple Angle Measurement software and eFILM to measure the angle Figure Demonstrating measure rotation and valgus cut angle by the software 2.1 Surgical technique applying femoral condyle rotation and valgus cut angle - Distal cutting slice based on intramedullary and valgus cut angle (the angle between mechanical axis and anatomical axis) (FMA Figure Distal cutting slice based on valgus cut angle JMR 118 E4 (2) - 2019 and FAA) - Anterior and posterior cutting slice based on the angle between sTEA and PCA - Other cutting slices is similar to normal total knee arthroplasty Figure Anterior and posterior cutting slice based on femoral rotated angle 39 JOURNAL OF MEDICAL RESEARCH III RESULTS 2.2 Collecting the data The variable research was collected following a medical record pattern Statistical analysis STATA 12.0 software to calculate p-value, T-test Age and sex characteristics The youngest patient is 55 years and oldest patient is 78 years The mean of age is 68.47 ± 12,06 years The ratio of male/female was 4/44 The femoral condyle rotational and the valgus cut angle Table The mean of rotation and valgus cut angle Mean Rotation angle 3.52º ± 1.86º (0.09º - 6.79º) Valgus angle 7.47º ± 1.25º (4.24º - 10.23º) The mean rotation and valgus angle were 3.52º and 7.47º respectively Table The mean of rotation angle in respect of gender Rotation angle Mean Male 3.52º ± 1.86º (0.09º - 6.79º) 3,28º ± 1,27º p = 0.75 (T-test) The mean rotation angle in male and female were 3.28º and 3,57º respectively There is no statistically significant difference Table The mean of valgus angle in relation to gender Valgus cut angle Average Male 7.47º ± 1.25º (4.24º - 10.23º) 7,28º ± 0,97º p = 0.5 (T-test) There is no statistically significant difference between male and female (p = 0.5) Table Mechanical axis between pre – operation and post - operation Mechanical axis p-value Pre-Op 15.47º ± 2.25º Post-Op 1.22º ± 0.45º 0.003 (T-test) The mechanical axis between pre-operation and post-operation are statistically significant difference (p = 0.003) 40 JMR 118 E4 (2) - 2019 JOURNAL OF MEDICAL RESEARCH Table The improvement in terms of KSS scoring KS score KFS score p-value Pre-Op 32.74 ± 0.36 39.35 ± 12.36