Tae Soo Bae

An Anatomical and Biomechanical Comparison of Anteromedial and Anterolateral Approaches for Tibial Tunnel of Posterior Cruciate Ligament Reconstruction: Evaluation of the Widening Effect of the Anterolateral Approach

Background An anterolateral approach to the tibial tunnel of posterior cruciate ligament reconstruction is used to reduce the sharpness of the graft-tunnel angle, the so-called killer turn effect. However, with the anterolateral approach, the tunnel might be widened into an ovoid shape because of the small angle between the tunnel and the anterolateral cortex. Hypothesis The fixation strength of the posterior cruciate ligament graft in the tibial tunnel will be weaker in the anterolateral approach compared with the anteromedial approach. Study Design Controlled laboratory study. Methods Twenty paired cadaveric tibias were used. Tibial tunnels were made using following approaches: an anteromedial approach for 10 tibias and an anterolateral approach for 10 tibias. The anterior cortex-tunnel angle and the diameter of the tunnel entrance were measured by 2-dimensional computed tomographic scans. After fixation of the Achilles tendon allograft with a biodegradable screw, the maximal strength of the graft at failure was measured using a materials testing machine. Results The mean cortex-tunnel angle was 47.5° ± 9.3° in the anteromedial approach group and 28.3° ± 7.4° in the anterolateral approach group. The mean long diameter of the tunnels in the anteromedial approach group was 10.6 ± 1.0 mm and in the anterolateral approach group it was 14.0 ± 1.5 mm. These two parameters showed statistically significant differences between the 2 groups (P < .01). The mean maximum load at failure for the anteromedial approach group was 385.4 ± 139.7 N, and for the anterolateral approach group it was 225.1 ± 144.1 N. This difference was statistically significant (P = .021). Conclusion The anterolateral approach resulted in a tunnel with a wider entrance, a more acute cortex-tunnel angle, and a lower maximal load at failure compared with tunnels created using the anteromedial approach. Clinical Relevance The use of additional fixation methods, such as post ties or ligament washers and screws, should be considered when using an anterolateral approach for tibial tunnel of posterior cruciate ligament reconstruction.

Effect of lumbar lordotic angle on lumbosacral joint during isokinetic exercise: A simulation study

BACKGROUND It is important to consider lumbar lordotic angle for setup of training program in field of sports and rehabilitation to prevent unexpected posture deviation and back pain. The purpose of this study was to to analyze the biomechanical impact of the level of lumbar lordosis angle during isokinetic exercise through dynamic analysis using a 3-dimensional musculoskeletal model. METHODS Gait analysis and isokinetic exercise for the healthy adults (n=10) were performed to design a 3-dimensional musculoskeletal model and then we made each model for normal lordosis, excessive lordosis, lumbar kyphosis, and hypo-lordosis according to lordotic angle and inputted experimental data as initial values to perform inverse dynamic analysis to quantify muscle joint torque, joint forces of each joint, system energy, and estimated muscle forces at lumbosacral joint. FINDINGS Comparing the joint torques, the largest torque of excessive lordosis was 16.6% larger than that of normal lordosis, and lumbar kyphosis was 11.7% less than normal lordosis. There existed no significant difference in the compressive intervertebral forces of each lumbar joint (P>0.05), but statistically significant difference in the anterioposterior shear force (lumbar kyphosis>hypo-lordosis>excessive lordosis>normal lordosis, P<0.05). Lastly, lumbar kyphosis required the least and most energy during flexion and extension respectively. INTERPRETATION During the rehabilitation process, more efficient training will be possible by taking into consideration not simply weight and height but biomechanical effects on the skeletal muscle system according to lumbar lordortic angles.