Isolated Posterior Cruciate Ligament Deficient Knee - In vivo kinematic evaluation using dynamic biplane radiography and model

In vivo kinematic evaluation using dynamic biplane radiography and model based trackingWang JH; Goyal K; Harner CD; +Tashman S Korea University, S. Korea ; +University of Pittsburgh, Pittsburgh, PA [email protected] INTRODUCTION: Even though PCL is strongest ligament of knee joint, it is considered that isolated PCL injury is often well tolerated. And the importance of the conservative treatment for the PCL injury is being emphasized due to good healing potential with plenty blood supply and synovium . However nonoperative treatment could maintain excellent muscle strength for the isolated PCL injury, degenerative change was increased with the increase of the duration. Osteoarthritis is related increased tangential shearing forces developed by instability after ligament injury. Evaluation of the instability might be the most important prognostic factor. The quantitative methods to evaluate the instability of the PCL injury are stress X-ray using Telos device and KT2000 arthrometer. But we couldn’t predict the dynamic instability with those static methods during the daily activity which could anticipate osteoarthritic change after posterior cruciate ligament (PCL) injury. The purpose of this study is to evaluate the functional instability of the PCL deficient knee compared to the contralateral normal knee during the daily activity such running and stair ascending activity. We hypothesized that the PCL deficient knee could be more functionally unstable than the contralateral normal knee. METHODS: Seven patients (range 18-28 years old) with isolated grade II PCL deficient knee underwent high-speed, biplane cine-radiography during level running (150frames/s) and stair ascending (100 frames/s) activity. The running activities were performed at 2.5m/s on instrumented dualbelt treadmill (Bertec, Inc.). The stair ascending activities were performed on the custom made three-steps based on the international residential code 2006 (tread: 11.5 inches, riser:7.75 inches). The mean interval between the injury time and the test time is 9.9 months. Patients underwent CT scan with 3D reconstruction using Mimics software (Materialise, Leuven, Belgium). Digitally reconstructed radiographs (DRRs) were generated with 3D reconstructed CT data via ray-traced projection. By optimizing the similarity between the two DRRs and the x-ray image pairs from biplane radiography, 3-D cine images of femoral and tibial bones during the activities was reproduced(Fig. 1). During the activity (level running and the stair ascending), the data about two translation parameters (anterior-posterior, medial-lateral) were collected using the relative value of tibial anatomic coordinate over the femoral anatomic coordinate, the data about two rotational parameters (internal/external rotation, abduction /adduction) were collected using the anatomic axis of the femur and tibia,. Paired t-test was used for the comparison of the parameter. p-value was set < .05.