Finite element (FE) analysis has become an increasingly popular technique in the study of human joint biomechanics, as it allows for detailed analysis of the joint/tissue behavior under complex, clinically relevant loading conditions. A wide variety of modeling techniques have been utilized to model knee joint ligaments. However, the effect of a selected constitutive model to simulate the ligaments on knee kinematics remains unclear. The purpose of the current study was to determine the effect of two most common techniques utilized to model knee ligaments on joint kinematics under functional loading conditions. We hypothesized that anatomic representations of the knee ligaments with anisotropic hyperelastic properties will result in more realistic kinematics. A previously developed, extensively validated anatomic FE model of the knee developed from a healthy, young female athlete was used. FE models with 3D anatomic and simplified uniaxial representations of main knee ligaments were used to simulate four functional loading conditions. Model predictions of tibiofemoral joint kinematics were compared to experimental measures. Results demonstrated the ability of the anatomic representation of the knee ligaments (3D geometry along with anisotropic hyperelastic material) in more physiologic prediction of the human knee motion with strong correlation (r ≥ 0.9 for all comparisons) and minimum deviation (0.9° ≤ RMSE ≤ 2.29°) from experimental findings. In contrast, non-physiologic uniaxial elastic representation of the ligaments resulted in lower correlations (r ≤ 0.6 for all comparisons) and substantially higher deviation (2.6°≤ RMSE
Aim: In this study, the relationship between the change in the joint line and lateral knee pain was evaluated after primary total knee arthroplasty. Material and method: Between 2005 and 2012, patients who underwent primary total knee arthroplasty were included in the study. Patients having “cruciate retaining total knee arthroplasty” and with a change of the joint line ≥8 mm and patients having “posterior stabilized total knee arthroplasty” and with a change of the joint line ≥5 mm were selected as the study group (group 1, n = 32). A total of 47 patients having similar demographic characteristics with the study group and the joint line changing below the predetermined level or remaining unchanged were included as the control group (group 2). The 2 groups were compared according to the presence of knee pain, the localization and spread of the pain, iliotibial band, tension and pain in the patellar tendon and quadriceps tendon, front knee pain during squatting, VAS pain score, OBER test positivity, Knee Society knee and function score, and general patient satisfaction. Results: There were statistically significant more lateral knee pain (p < 0.001), OBER test positivity (p < 0.001) and iliotibial band tension (p < 0.001) in group 1 compared to group 2. However, there were no statistically significant differences between the 2 groups regarding rest pain (p = 0.855), pain during squatting (p = 0.761), exertional pain (p = 0.322), pain in the patellar tendon (p = 0.643) and quadriceps tendon (p = 0.873), Knee Society knee (p = 0.954) and function (p = 0.955) scores, and general satisfaction (p = 0.968). Conclusion: In total knee prosthesis operations, distal displacement of the joint line can result in lateral knee pain and iliotibial band tension. However, considering the results of total knee arthroplasty our findings have showed that this condition has no effect on knee functions and patient satisfaction.