Yukihide Iwamoto

Evaluation of Skills in Arthroscopic Training Based on Trajectory and Force Data

Objective evaluation of surgical skills is essential for an arthroscopic training system. We asked whether a quantitative assessment of arthroscopic skills using scores, time to completion, instrument tip trajectory data, and force data was valid. We presumed more experienced surgeons would perform better on a simulated arthroscopic procedure than novices, therefore validating the quantitative assessment. Surgical trainees (nxa0=xa012), orthopaedic residents (nxa0=xa012), and experienced arthroscopic surgeons (nxa0=xa06) were tested on a Sawbones® knee simulator. Subjects performed a joint inspection and probing task and a partial meniscectomy task. The trajectory data were measured using an electromagnetic motion tracking system and the force data were measured using a force sensor. The experienced group performed both tasks with higher scores and more quickly than the less experienced groups. The path length of the probe and the scissors was substantially shorter and the probe velocity was considerably faster in the experienced group. The trainee group applied substantially stronger forces to the joint during the joint inspection and probing task. Our data suggest a performance assessment using an electromagnetic motion tracking system and a force sensor provides an objective means of evaluating surgical skills in an arthroscopic training system.

Quantitative assessment of rotatory instability after anterior cruciate ligament reconstruction

Background Anterior cruciate ligament reconstruction successfully reduces anterior knee instability, but its effect on rotatory stability is not fully understood. In addition, a definitive method for the quantitative evaluation of rotatory instability remains to be established. Hypothesis Measurement of anterolateral tibial translation by open magnetic resonance imaging could positively correlate with the clinical grading of the pivot-shift test and would clarify residual rotatory abnormalities not shown by conventional methods for measurement of anterior stability. Study Design Controlled laboratory study. Methods An anterior cruciate ligament—reconstructed group (n = 21) and an anterior cruciate ligament—deficient group (n = 20) were examined using a Slocum anterolateral rotatory instability test in open magnetic resonance imaging. Anterior tibial translation was measured at the medial and lateral compartments by evaluating sagittal images. Clinical knee stability was evaluated before the above measurement using the pivot-shift test, KT-2000 arthrometer, and stress radiography. A cutoff value for anterolateral tibial translation relating to pivot-shift was determined using a receiver operating characteristic curve. Results Side-to-side differences of anterolateral tibial translation correlated with clinical grade of the pivot-shift test and stress radiography but not with KT-2000 arthrometry in both groups. The cutoff value was established as 3.0 mm. Although the mean anterolateral translation showed no difference, 9 reconstructed knees revealed greater than 3 mm of anterolateral tibial translation, whereas only 3 uninjured knees did. Conclusion Measurement using an open magnetic resonance imaging successfully quantified the remaining rotatory instability in anterior cruciate ligament—reconstructed knees. Clinical Relevance This method is a useful means for quantifying anterior cruciate ligament function to stabilize tibial rotation.

Comparison of Rotatory Stability After Anterior Cruciate Ligament Reconstruction Between Single-Bundle and Double-Bundle Techniques:

Background: Controversy persists as to whether double-bundle reconstruction of the anterior cruciate ligament (ACL) has any clinical advantage over single-bundle reconstruction. Several studies have used subjective and nonquantitative manual tests to evaluate the rotatory stability of the knee. The authors have developed a method to quantitate the rotatory stability of the ACL-deficient knee using open magnetic resonance imaging (MRI). Hypothesis: Anatomic double-bundle reconstruction restores rotatory stability significantly better than does single-bundle reconstruction. Study Design: Cohort study; Level of evidence, 3. Methods: Twenty-three consecutive patients treated with the single-bundle reconstruction (group S) and 25 consecutive patients treated with the anatomic double-bundle reconstruction (group D) were evaluated. Both reconstruction procedures were performed using hamstring tendon autografts. The Slocum anterolateral rotatory instability (ALRI) test was performed 1 year after surgery using open MRI. To assess rotatory stability, we measured the difference in anterior tibial translation between medial and lateral compartments in the sagittal plane and defined this difference as the ALRI value. In addition, clinical examinations consisting of the Lysholm knee score, Tegner activity score, KT-2000 arthrometer anterior translation examination, and the pivot-shift test were carried out. Results: The mean side-to-side difference in ALRI values was significantly less (P < .001) in double-bundle reconstruction (mean, 1.2 mm) than in single-bundle reconstruction (mean, 4.1 mm). The mean side-to-side difference in KT-2000 arthrometer measurements was significantly less (P = .014) in double-bundle reconstruction (mean, 1.2 mm) than in single-bundle reconstruction (mean, 2.6 mm). The difference in the incidence of positive pivot-shift tests between group S (43%) and group D (16%) did not reach the level of statistical significance (P = .058). No significant differences in Lysholm score or Tegner score between the groups were observed. Conclusion: The rotatory stability of anatomic double-bundle reconstruction was significantly better than the rotatory stability of single-bundle reconstruction.

In Vivo Healthy Knee Kinematics during Dynamic Full Flexion

Healthy knee kinematics during dynamic full flexion were evaluated using 3D-to-2D model registration techniques. Continuous knee motions were recorded during full flexion in a lunge from 85° to 150°. Medial and lateral tibiofemoral contacts and femoral internal-external and varus-valgus rotations were analyzed as a function of knee flexion angle. The medial tibiofemoral contact translated anteroposteriorly, but remained on the center of the medial compartment. On the other hand, the lateral tibiofemoral contact translated posteriorly to the edge of the tibial surface at 150° flexion. The femur exhibited external and valgus rotation relative to the tibia over the entire activity and reached 30° external and 5° valgus rotations at 150° flexion. Kinematics data during dynamic full flexion may provide important insight as to the designing of high-flexion total knee prostheses.

No influence of coronal laxity and alignment on lift-off after well-balanced and aligned total knee arthroplasty

PurposeIn vivo fluoroscopic analyses have revealed the kinematics after total knee arthroplasty (TKA), including femoral condylar lift-off. This study asked whether differences in static varus–valgus laxity or coronal limb alignment after TKA affect lift-off under weight-bearing conditions. It was hypothesised that there is a correlation between coronal laxity or alignment and lift-off during walking.MethodsThe current study analysed nineteen subjects undergoing cruciate-retaining TKA performed by the measured resection technique. The varus–valgus laxity at knee extension was measured using a 150xa0N stress radiograph. The mechanical axis was measured using a full-standing radiograph. Continuous radiological images were taken while the subject walked on a treadmill, and the images during single-leg stance were analysed to determine the lift-off using a 3D-to-2D image-to-model registration technique.ResultsThe average angle in varus/valgus stress was 6.8xa0±xa01.8°/6.6xa0±xa02.1°. No statistically significant differences were observed between the varus and valgus laxity. The average amount of lift-off was 0.7xa0±xa00.4xa0mm. The static varus–valgus laxity (n. s.) or the differences in the laxities (n. s.) on the stress radiograph did not influence lift-off. The weight-bearing ratio was achieved within the middle third of the knee in 90xa0% of subjects. Two outliers with valgus alignment (68xa0±xa01xa0%) demonstrated no significant difference in lift-off in comparison with the majority of the subjects (46xa0±xa09xa0%).ConclusionThe static coronal laxity and alignment did not influence the lift-off under dynamic weight-bearing conditions after well-balanced and aligned cruciate-retaining TKA. Measured resection technique can produce sufficient coronal stability and alignment without significant lift-off during walking.Level of evidenceIV.

Kinematic Analysis of Healthy Hips during Weight-Bearing Activities by 3D-to-2D Model-to-Image Registration Technique

Dynamic hip kinematics during weight-bearing activities were analyzed for six healthy subjects. Continuous X-ray images of gait, chair-rising, squatting, and twisting were taken using a flat panel X-ray detector. Digitally reconstructed radiographic images were used for 3D-to-2D model-to-image registration technique. The root-mean-square errors associated with tracking the pelvis and femur were less than 0.3u2009mm and 0.3° for translations and rotations. For gait, chair-rising, and squatting, the maximum hip flexion angles averaged 29.6°, 81.3°, and 102.4°, respectively. The pelvis was tilted anteriorly around 4.4° on average during full gait cycle. For chair-rising and squatting, the maximum absolute value of anterior/posterior pelvic tilt averaged 12.4°/11.7° and 10.7°/10.8°, respectively. Hip flexion peaked on the way of movement due to further anterior pelvic tilt during both chair-rising and squatting. For twisting, the maximum absolute value of hip internal/external rotation averaged 29.2°/30.7°. This study revealed activity dependent kinematics of healthy hip joints with coordinated pelvic and femoral dynamic movements. Kinematics data during activities of daily living may provide important insight as to the evaluating kinematics of pathological and reconstructed hips.

Continuous Sagittal Radiological Evaluation of Stair-Climbing in Cruciate-Retaining and Posterior-Stabilized Total Knee Arthroplasties Using Image-Matching Techniques

In this study, we evaluated the in vivo kinematics of stair-climbing after posterior stabilized (PS) and cruciate retaining (CR) total knee arthroplasty (TKA) using radiographic-based image-matching techniques. Mid-flexion anteroposterior stability was demonstrated in all knees after CR TKA. However, paradoxical femoral translation at low flexion angles was seen in both designs. The post-cam mechanism did not function after PS TKA. Larger posterior tibial slope in PS TKA was linked to forward sliding of the femur at mid-flexion and unintended anterior tibial post impingement at knee extension. CR TKA is more sagittally stable in mid-flexion during stair climbing and attention must be given to minimize posterior tibial slope when using late cam-post engaging PS TKA designs.

The biomechanical assessment of gap formation after flexor tendon repair using partial interlocking cross-stitch peripheral sutures

The gap formation of five core plus peripheral suture techniques for flexor tendon repair was evaluated by cyclic load testing. Fifty pairs of dental roll tendon models were sutured using six-strand Pennington modified Kessler core suture with 4-0 Polypropylene. One-half or three-fourths circumferential interlocking cross-stitch, or three complete circumferential peripheral suture techniques were performed using 6-0 Polypropylene. An initial cyclic load of 10u2009N for 500 cycles was applied and increased by 5u2009N for an additional 500 cycles at each new load until rupture. The complete circumferential interlocking cross-stitch had the greatest fatigue strength. The partial circumferential cross-stitches resulted in significantly larger gap formations at both the repaired and unrepaired sides than the complete circumferential sutures, and were also associated with early rupture. The full circumference of the cut tendon must be sutured using an interlocking cross-stitch peripheral suture to improve strength and avoid gap formation.

Bio Rapid Prototyping Project: Development of Spheroid Formation System for Regenerative Medicine

Cells construct is made by spheroid-culturing the cells and collecting the spheroids. The spheroids are manufactured by dispensing cell turbid liquid into a special multiwell plate. If there is a difference in the number of cells when dispensing the cells turbid liquid, spheroids in different sizes are generated. Moreover, spheroids are not generated if the number of cells is extremely small, and if large, spheroids in distorted shapes are generated. Therefore, this study was aimed to develop a system that generates similar spheroids. In result, all the spheroids generated using developed system came in a pure spherical shape, and generation of spheroids is confirmed on all the wells.