Analysis of relationship between loading condition and cranial cracking pattern using a three-dimensional finite element model.

Background: A hairline crack on the cranium can occur even under a small external load or impact and are thus often observed in patients who have experienced an accidental fall or collision. Typical finite element analysis is useful to analyze the stress concentration or the propagation of stress waves. However, a stress propagation model does not accurately reproduce the features of hairline cracks on the cranium.

Application of an indentation sensor for the arthroscopic measurement of articular cartilage stiffness.

Direct measurement of cartilage stiffness provides useful clinical information and enables us to develop treatment strategies for patients. We applied an indentation sensor to evaluate cartilage stiffness under arthroscopic control. The purpose of this study was to validate the arthroscopic indentation sensor using cadaver knees and to measure cartilage stiffness in clinical cases.

Three-Dimensional Deformities of Nonoperative Midshaft Clavicle Fractures: A Surface Matching Analysis.

Objective: The purpose of this study was to describe the 3-dimensional deformities of midshaft clavicle fractures, which had been treated nonoperatively, using computed tomography (CT) surface matching.

Methods: Twenty-one patients with unilateral midshaft clavicle fracture, who had been treated nonoperatively, were enrolled and evaluated retrospectively. The 3-dimensional deformity of the fractured clavicle was evaluated by CT surface matching.

Analysis of the factors that correlate with increased knee adduction moment during gait in the early postoperative period following total knee arthroplasty.

Background: Analysis of dynamic knee loading during gait is essential to prevent mechanical failures following total knee arthroplasty. External knee adduction moment during gait is the primary factor producing medial joint reaction force, and an increase in the moment is directly related to an increase in the medial compartment load on the knee.

Methods: Knee adduction moment during gait in 39 knees of 32 female patients following a posterior stabilized knee replacement with a single surgeon was evaluated at 1.

Kinematic motion of the anterior cruciate ligament deficient knee during functionally high and low demanding tasks.

The purpose of this study was to determine whether mechanical adaptations were present in patients with anterior cruciate ligament (ACL)-deficient knees during high-demand activities. Twenty-two subjects with unilateral ACL deficiency (11 males and 11 females, 19.6 months after injury) performed five different activities at a comfortable speed (level walking, ascending and descending steps, jogging, jogging to a 90-degree side cutting toward the opposite direction of the tested side).

A miniature tension sensor to measure surgical suture tension of deformable musculoskeletal tissues during joint motion.

The aim of this study was to develop a new suture tension sensor for musculoskeletal soft tissue that shows deformation or movements. The suture tension sensor was 10 mm in size, which was small enough to avoid conflicting with the adjacent sensor. Furthermore, the sensor had good linearity up to a tension of 50 N, which is equivalent to the breaking strength of a size 1 absorbable suture defined by the United States Pharmacopeia.

Quantification of the spatial strain distribution of scoliosis using a thin-plate spline method.

The objective of this study was to quantify the three-dimensional spatial strain distribution of a scoliotic spine by nonhomogeneous transformation without using a statistically averaged reference spine. The shape of the scoliotic spine was determined from computed tomography images from a female patient with adolescent idiopathic scoliosis. The shape of the scoliotic spine was enclosed in a rectangular grid, and symmetrized using a thin-plate spline method according to the node positions of the grid.

Female recreational athletes demonstrate different knee biomechanics from male counterparts during jumping rope and turning activities.

Background: A variety of athletic exercises are performed in sports training or rehabilitation after knee injuries. However, it remains unclear whether males and females exhibit similar joint loading during the various athletic motions. The purpose of this study was to identify gender differences in knee biomechanics during the athletic motions.

Acromioclavicular joint ligamentous system contributing to clavicular strut function: a cadaveric study.

Hypothesis: We hypothesized that the clavicle overrides the acromion during certain shoulder motions for individuals with acromioclavicular (AC) joint separation producing clinical symptoms. We measured 3-dimensional clavicular and scapular motions in AC joint separation models during humerothoracic motions, which should be impacted by the loss of AC joint continuity.

Materials And Methods: Ten shoulders from 6 whole cadavers were used.

Comparison of knee mechanics among risky athletic motions for noncontact anterior cruciate ligament injury.

It has been suggested that noncontact anterior cruciate ligament injury commonly occurs during sports requiring acute deceleration or landing motion and that female athletes are more likely to sustain the injury than male athletes. The purpose of this study was to make task-to-task and male-female comparisons of knee kinematics and kinetics in several athletic activities. Three-dimensional knee kinematics and kinetics were investigated in 20 recreational athletes (10 males, 10 females) while performing hopping, cutting, turning, and sidestep and running (sharp deceleration associated with a change of direction).

The function of the acromioclavicular and coracoclavicular ligaments in shoulder motion: a whole-cadaver study.

Background: Scapulothoracic dyskinesis is an important consequence of acromioclavicular joint dislocations. However, no reports have described changes in 3-dimensional motions of the scapula and clavicle with respect to the thorax caused by acromioclavicular joint dislocation.

Hypothesis: Sectioning of the acromioclavicular (AC) and coracoclavicular (CC) ligaments affects scapular and clavicular motion in a whole-cadaver model.

A quantitative assessment of varus thrust in patients with medial knee osteoarthritis.

Varus thrust is an abnormal lateral knee motion frequently seen in patients with medial knee osteoarthritis (OA) during gait. It is a worsening of the alignment in the stance phase of the gait cycle and closely relates to disease progression. In this study, we measured the thrust quantitatively using skin markers and examined the relationship to other static and dynamic parameters.

Computer simulation of humeral shaft fracture in throwing.

Hypothesis: Throwing fractures of the humerus are well known, but the exact mechanism of injury is not clear. It has been postulated that these may be stress fractures because the forces have not seemed sufficient to cause acute fractures while throwing.

Materials And Methods: Using finite element analysis, we reproduced fractures of the humerus using 3-dimensional models built from computed tomography images of 5 healthy volunteers.

Tibiofemoral joint contact force in deep knee flexion and its consideration in knee osteoarthritis and joint replacement.

The aim of the study was to estimate the tibiofemoral joint force in deep flexion to consider how the mechanical load affects the knee. We hypothesize that the joint force should not become sufficiently large to damage the joint under normal contact area, but should become deleterious to the joint under the limited contact area. Sixteen healthy knees were analyzed using a motion capture system, a force plate, a surface electromyography, and a knee model, and then tibiofemoral joint contact forces were calculated.