Published papers

The purpose of the current study was to investigate inpatient recovery process during relaxed standing, and to clarify the question of when postoperative standing function would improve beyond preoperative level of function following total knee arthroplasty (TKA). Thirty patients with bilateral knee osteoarthritis, averaged 75 years old, participated. Subjects underwent unilateral TKA. Evaluations were divided into two categories; subjective and objective components. Subjective component was based on pain level (Visual Analog Scale: 100 mm), and objective component consisted of vertical knee force (%BW) and knee flexion angle (degrees) during relaxed standing. Data evaluations were done pre- and post-operatively. Preoperative pain score was 69.1. After TKA, pain level became maximum (89.9) and significantly larger on postoperative day 3. Thereafter, pain gradually decreased, and it (60.4) was significantly smaller on postoperative day 8 than preoperative score. Preoperative vertical knee force was 43.5%BW. After TKA, it became minimum (32.8) on postoperative day 3. Thereafter, knee force gradually increased, and it (44.1) was significantly larger on postoperative day 17. Preoperative knee flexion angle was 15.6°. After TKA, knee flexion angle during standing became maximum (20.0) on postoperative day 4. Thereafter, subjects could gradually extend the knee, and on postoperative day 16, it (14.3°) was smaller. From our results, subjective pain was significantly reduced from postoperative day 8, and objective knee condition, including vertical knee force on TKA side and knee flexion angle on TKA side during standing, significantly became better from postoperative day 17 and 16, respectively. © 2008 Elsevier B.V. All rights reserved.

The purpose of the current study was to investigate the effect of knee flexion contracture on the knee mechanics both in affected and contralateral limbs during gait. Ten healthy old women, with mean age of 62 years, participated. Unilateral knee flexion contractures of 0, 15, and 30° were simulated with a knee brace. All subjects performed walking trials with or without the simulation. Net knee extension moments, net knee adduction moments (%BW Ht), external knee forces (%BW), and maximum axial loading rate (%BW/s) at the knee were calculated both in contracture side and non-contracture side under different contracture conditions. Bilateral net knee extension moment gradually increased as the angle of contracture increased. The net knee extension moments in non-contracture limb were significantly larger with 15 and 30° contracture than those without the contracture. Net knee adduction moment in non-contracture limb significantly increased with 15 and 30° contracture. The knee shearing forces in contracture side and the knee compressive force in non-contracture side also significantly increased with 15 and 30° simulation. As the flexion contracture became greater than 15°, maximum axial loading rate also significantly increased in non-contracture side. From our results, the knee flexion contracture greater than 15° led to mechanical overloads in both limbs. Correction of the contracture is clinically important to avoid any adverse effect. © 2008 Elsevier B.V. All rights reserved.

Knee flexion contracture influences the physiological movements in lower extremities and may cause the kinematic changes of the trunk. Our purpose was to investigate static and dynamic changes in trunk kinematics with simulated knee flexion contracture. Ten healthy females averaged 62 years participated in our study. Unilateral knee flexion contractures of 15° and 30° were simulated with a knee brace. Relaxed standing and level walking were measured at our laboratory using a motion analysis system which consisted of five cameras, a force plate, and thirteen retro-reflective markers. Three-dimensional trunk kinematics and vertical knee forces (% Body Weight) with the contractures were compared with those without the contracture. The 15° contracture did not significantly change trunk kinematics. However, the 30° contracture significantly changed the kinematics in each of the following planes. In the coronal plane, the trunk tilted to the contracture side in standing and walking. In the sagittal plane, posterior inclination of the pelvis in standing significantly increased. In addition, anterior inclination of the trunk and pelvis during walking significantly increased. In the axial plane, trunk rotation to the unaffected side significantly decreased during walking. The vertical knee force in the contracture limb decreased, being accompanied by the increase of the force in the unaffected limb during standing and walking. Results of our study suggest that knee flexion contracture significantly influences three-dimensional trunk kinematics during relaxed standing and level walking, and will lead to spinal imbalance. These facts may explain the onset of the "Knee-Spine Syndrome". © 2008 Elsevier B.V. All rights reserved.

The purpose of the current study was to compare midterm outcomes of posterior cruciate-retaining (CR) versus posterior cruciate-substituting (PS) procedures using the Genesis II total knee arthroplasty (TKA) system (Smith and Nephew, Memphis, TN). Ninety-nine (99) CR and 93 PS TKA's were analyzed in this prospective, randomized clinical trial. Surgeries were performed at seven medical centers by participating surgeons. Clinical outcomes (Knee Society Score, Range of Motion, WOMAC, SF-12, and Radiographic Findings), in addition to postoperative complications, were evaluated with a minimum follow-up of 5 years. Following data analysis, there were no significant differences in patient demographics or preoperative clinical measures between the two groups. At the latest follow-up interval, no significant differences were found between the CR and PS groups with regards to functional assessment, patient satisfaction, or postoperative complication. However, the PS group did display statistically significant improvements in range of motion when compared with the CR group. The results of this investigation would suggest that, while comparable in regards to supporting good clinical outcomes, the PS Genesis II design does appear to support significantly improved postoperative range of motion when compared with the CR design. © 2007 Elsevier B.V. All rights reserved.