The Experts below are selected from a list of 20151 Experts worldwide ranked by ideXlab platform

Bo Sanderhoff Olsen - One of the best experts on this subject based on the ideXlab platform.

  • Treatment of the stiff Elbow Joint
    Orthopaedics and Trauma, 2012
    Co-Authors: Bo Sanderhoff Olsen
    Abstract:

    Abstract Elbow Joint stiffness is a significant problem after Elbow trauma, in degenerative and arthritic Elbow Joint disease, and following surgery to the Elbow Joint. Treatment of the disease can be difficult and it requires a team that can access a range of conservative and surgical treatment options. This paper describes the clinical presentation of the disease, its causes, diagnosis and management. The results obtained after treatment will be discussed, based both on the current literature and the senior authors extensive personal experience in treating patients with Elbow Joint stiffness.

  • Elbow Joint kinematics after excision of the radial head.
    Journal of shoulder and elbow surgery, 1999
    Co-Authors: Steen Lund Jensen, Bo Sanderhoff Olsen, Jens Ole Søjbjerg
    Abstract:

    Abstract The contribution of the radial head to Elbow Joint kinematics was studied in 7 osteoligamentous Elbow preparations. During unloaded flexion and extension, radial head excision induced a maximum varus displacement of 1.6° with 20° of Joint flexion and a maximum external rotation of 3.2° at 110° of flexion. With application of a 0.75-Nm load, radial head excision induced a maximum laxity of 3.3° at 20° of flexion in forced varus and a maximum laxity of 8.9° at 10° of flexion in forced external rotation. No laxity was observed in forced valgus or internal rotation. The results were independent of the rotation of the forearm. This study indicates that the radial head acts as stabilizer to the Elbow Joint in forced varus and in forced external rotation. The results suggest that fractures of the radial head cannot be treated by simple excision without altering the basic kinematics of the Elbow Joint.

  • posterolateral Elbow Joint instability the basic kinematics
    Journal of Shoulder and Elbow Surgery, 1998
    Co-Authors: Bo Sanderhoff Olsen, Jens Ole Søjbjerg, Michel Dalstra, K K Nielsen, M T Vaesel, Otto Sneppen
    Abstract:

    Thirty-five osteoligamentous Elbows were included in a study on the kinematics of posterolateral Elbow Joint instability during the pivot shift test (PST) before and after separate ligament cuttings in the lateral collateral ligament complex (LCLC). Division of the annular ligament or the lateral ulnar collateral ligament caused no laxity during the PST. Division of the lateral collateral ligament caused maximal laxity of 4 degrees and 23 degrees during forced PST in valgus and external rotation (supination), respectively. Cutting of the LCLC at the ulnar or the humeral insertion was necessary for any PST stressed Elbow Joint laxity to occur. Total division of the LCLC induced a maximal laxity of 7.9 degrees and 37 degrees during forced PST in valgus and external rotation (supination), respectively. This study suggests the lateral collateral ligament to be the primary soft tissue constraint to PST stress and the annular ligament and the lateral ulnar collateral ligament to be only secondary constraints. This study indicates that the integrity of the medial collateral Elbow ligaments should be evaluated during forced valgus in pronation or neutral forearm rotation. Furthermore an isometric lateral collateral ligament reconstruction was shown to correct the Joint laxity introduced by total LCLC transection.

  • Kinematics of the lateral ligamentous constraints of the Elbow Joint.
    Journal of shoulder and elbow surgery, 1996
    Co-Authors: Bo Sanderhoff Olsen, Jens Ole Søjbjerg, Michel Dalstra, Sneppen O
    Abstract:

    Thirty osteoligamentous Elbow Joint specimens were included in a study of the lateral collateral ligament complex (LCLC). The morphologic characteristics of the LCLC were examined, and then three-dimensional kinematic measurements were undertaken after selective ligament dissections were performed. Isolated sectioning of the annular ligament (AL) or the lateral ulnar collateral ligament (LUCL) induced only minor laxity to the Elbow Joint with a maximum of 2.2 degrees and 4.4 degrees during forced varus and external rotation (supination), respectively. Transsection of the lateral collateral ligament (LCL) caused a maximal laxity of 15.4 degrees and 22.8 degrees during forced varus and external rotation (supination), respectively. Combined ligament dissections showed that total transection of the LCLC at the ulnar or the humeral insertion was important for Joint laxity. Total transection of the LCLC at the humeral or the ulnar insertion induced a maximal laxity of 24.5 degrees and 37 degrees during forced varus and external rotation (supination), respectively. This study suggests the AL and the LUCL are of minor importance as constraints when cut separately, whereas the LCL is a significant preventer of Elbow Joint laxity. The LCLC was observed to be a complex structure of ligamentous fibers rather than discreet bands. The LCLC forms a ligamentous constraint between the lateral humeral epicondyle and the ulna, stabilizing the Elbow Joint and forming a base for radial head stability and rotation.

  • Elbow Joint instability: A kinematic model
    Journal of shoulder and elbow surgery, 1994
    Co-Authors: Bo Sanderhoff Olsen, Morten G. Henriksen, Jens Ole Søjbjerg, Peter Helmig, Sneppen O
    Abstract:

    The effect of simultaneous ulnar and radial collateral ligament division on the kinematics of the Elbow Joint is studied in a cadaveric model. Severance of the anterior part of the ulnar collateral ligament and the annular ligament led to significant Elbow Joint instability in valgus and varus stress and in forced external and internal rotation. The mean maximum laxity in valgus stress and forced external rotation were 5.7° and 13.2°. The forearms of the Elbow Joint specimens were transfixed in maximum pronation. During valgus and varus stress the corresponding spontaneous ulnar rotation of the specimens was recorded. The reproducibility of the instability pattern suggests that this model is suitable for evaluating stabilizing procedures aimed at correction of Elbow Joint instability before these procedures are introduced into patient care.

Kenzo Akazawa - One of the best experts on this subject based on the ideXlab platform.

  • Estimating Torque-Angle Relations of Human Elbow Joint in Isovelocity Flexion Movements
    IEICE Transactions on Information and Systems, 2006
    Co-Authors: Kenzo Akazawa, Ryuhei Okuno
    Abstract:

    We investigated relations between torque and Elbow Joint angle for constant muscle activations in isovelocity flexion movements of the forearm in three normal subjects. The reference angular velocity was from 0 to 90°/s and the applied torque from 0 to 15% of maximum voluntary contraction. Integrated surface electromyograms (IEMGs) of six muscles, torque, angle and angular velocity of the Elbow Joint were measured. A mathematical model describing the relationship between these variables was constructed with an artificial neural network. We estimated Elbow Joint torque by presenting different Elbow Joint angles, constant IEMGs and constant angular velocity to the model. For Elbow Joint angles greater than 60°, the slope, which was defined as the rate of torque increase with respect to Elbow Joint angle, was negative. For Elbow Joint angles less than 50°, the slope changed from positive to negative when the angular velocity increased. This implied that the flexor muscle-Elbow Joint system could change from unstable to stable when the angular velocity increased.

  • static torque angle relation of human Elbow Joint estimated with artificial neural network technique
    Journal of Biomechanics, 1998
    Co-Authors: Takanori Uchiyama, Tomoyuki Bessho, Kenzo Akazawa
    Abstract:

    Abstract Static relations between Elbow Joint angle and torque at constant muscle activity in normal volunteers were investigated with the aid of an artificial neural network technique. A subject sat on a chair and moved his upper- and forearm in a horizontal plane at the height of his shoulder. The subject was instructed to maintain the Elbow Joint at a pre-determined angle. The wrist was then pulled to extend the Elbow Joint by the gravitational force of a weight hanging from a pulley. Integrated electromyograms (IEMGs), Elbow and shoulder Joint angles and Elbow Joint torque were measured. Then the relation among IEMGs, Joint angles and torque was modeled with the aid of the artificial neural network, where IEMGs and Joint angles were the inputs and torque was the output. After back propagation learning, we presented various combinations of IEMGs, shoulder and Elbow Joint angles to the model and estimated the Elbow Joint torque to obtain the torque–angle relation for constant muscle activation. The Elbow Joint torque increased and then decreased with extension of the Elbow Joint. This suggests that if the forearm is displaced from an equilibrium point, the torque–angle relation would not act like a simple spring. In a view of the musculoskeletal structure of the Elbow Joint, the relation between the Elbow Joint angle and the moment arm of the Elbow flexor muscles seems to have a dominant effect on the torque–angle relation.

Jens Ole Søjbjerg - One of the best experts on this subject based on the ideXlab platform.

  • Elbow Joint kinematics after excision of the radial head.
    Journal of shoulder and elbow surgery, 1999
    Co-Authors: Steen Lund Jensen, Bo Sanderhoff Olsen, Jens Ole Søjbjerg
    Abstract:

    Abstract The contribution of the radial head to Elbow Joint kinematics was studied in 7 osteoligamentous Elbow preparations. During unloaded flexion and extension, radial head excision induced a maximum varus displacement of 1.6° with 20° of Joint flexion and a maximum external rotation of 3.2° at 110° of flexion. With application of a 0.75-Nm load, radial head excision induced a maximum laxity of 3.3° at 20° of flexion in forced varus and a maximum laxity of 8.9° at 10° of flexion in forced external rotation. No laxity was observed in forced valgus or internal rotation. The results were independent of the rotation of the forearm. This study indicates that the radial head acts as stabilizer to the Elbow Joint in forced varus and in forced external rotation. The results suggest that fractures of the radial head cannot be treated by simple excision without altering the basic kinematics of the Elbow Joint.

  • posterolateral Elbow Joint instability the basic kinematics
    Journal of Shoulder and Elbow Surgery, 1998
    Co-Authors: Bo Sanderhoff Olsen, Jens Ole Søjbjerg, Michel Dalstra, K K Nielsen, M T Vaesel, Otto Sneppen
    Abstract:

    Thirty-five osteoligamentous Elbows were included in a study on the kinematics of posterolateral Elbow Joint instability during the pivot shift test (PST) before and after separate ligament cuttings in the lateral collateral ligament complex (LCLC). Division of the annular ligament or the lateral ulnar collateral ligament caused no laxity during the PST. Division of the lateral collateral ligament caused maximal laxity of 4 degrees and 23 degrees during forced PST in valgus and external rotation (supination), respectively. Cutting of the LCLC at the ulnar or the humeral insertion was necessary for any PST stressed Elbow Joint laxity to occur. Total division of the LCLC induced a maximal laxity of 7.9 degrees and 37 degrees during forced PST in valgus and external rotation (supination), respectively. This study suggests the lateral collateral ligament to be the primary soft tissue constraint to PST stress and the annular ligament and the lateral ulnar collateral ligament to be only secondary constraints. This study indicates that the integrity of the medial collateral Elbow ligaments should be evaluated during forced valgus in pronation or neutral forearm rotation. Furthermore an isometric lateral collateral ligament reconstruction was shown to correct the Joint laxity introduced by total LCLC transection.

  • Kinematics of the lateral ligamentous constraints of the Elbow Joint.
    Journal of shoulder and elbow surgery, 1996
    Co-Authors: Bo Sanderhoff Olsen, Jens Ole Søjbjerg, Michel Dalstra, Sneppen O
    Abstract:

    Thirty osteoligamentous Elbow Joint specimens were included in a study of the lateral collateral ligament complex (LCLC). The morphologic characteristics of the LCLC were examined, and then three-dimensional kinematic measurements were undertaken after selective ligament dissections were performed. Isolated sectioning of the annular ligament (AL) or the lateral ulnar collateral ligament (LUCL) induced only minor laxity to the Elbow Joint with a maximum of 2.2 degrees and 4.4 degrees during forced varus and external rotation (supination), respectively. Transsection of the lateral collateral ligament (LCL) caused a maximal laxity of 15.4 degrees and 22.8 degrees during forced varus and external rotation (supination), respectively. Combined ligament dissections showed that total transection of the LCLC at the ulnar or the humeral insertion was important for Joint laxity. Total transection of the LCLC at the humeral or the ulnar insertion induced a maximal laxity of 24.5 degrees and 37 degrees during forced varus and external rotation (supination), respectively. This study suggests the AL and the LUCL are of minor importance as constraints when cut separately, whereas the LCL is a significant preventer of Elbow Joint laxity. The LCLC was observed to be a complex structure of ligamentous fibers rather than discreet bands. The LCLC forms a ligamentous constraint between the lateral humeral epicondyle and the ulna, stabilizing the Elbow Joint and forming a base for radial head stability and rotation.

  • Elbow Joint instability: A kinematic model
    Journal of shoulder and elbow surgery, 1994
    Co-Authors: Bo Sanderhoff Olsen, Morten G. Henriksen, Jens Ole Søjbjerg, Peter Helmig, Sneppen O
    Abstract:

    The effect of simultaneous ulnar and radial collateral ligament division on the kinematics of the Elbow Joint is studied in a cadaveric model. Severance of the anterior part of the ulnar collateral ligament and the annular ligament led to significant Elbow Joint instability in valgus and varus stress and in forced external and internal rotation. The mean maximum laxity in valgus stress and forced external rotation were 5.7° and 13.2°. The forearms of the Elbow Joint specimens were transfixed in maximum pronation. During valgus and varus stress the corresponding spontaneous ulnar rotation of the specimens was recorded. The reproducibility of the instability pattern suggests that this model is suitable for evaluating stabilizing procedures aimed at correction of Elbow Joint instability before these procedures are introduced into patient care.

Charles J. Robinson - One of the best experts on this subject based on the ideXlab platform.

  • Dependence of Elbow Joint stiffness measurements on speed, angle, and muscle contraction level
    Journal of biomechanics, 2013
    Co-Authors: Laurel Kuxhaus, Sisi Zeng, Charles J. Robinson
    Abstract:

    Elbow Joint stiffness is critical to positioning the hand. Abnormal Elbow Joint stiffness may affect a person's ability to participate in activities of daily living. In this work, Elbow Joint stiffness was measured in ten healthy young adults with a device adapted from one previously used to measure stiffness in other Joints. Measurements of Elbow stiffness involved applying a constant-velocity rotational movement to the Elbow and measuring the resultant displacement, torque, and acceleration. Elbow stiffness was then computed using a previously-established model for Joint stiffness. Measurements were made at two unique Elbow Joint angles, two speeds, and two forearm muscle contraction levels. The results indicate that the Elbow Joint stiffness is significantly affected by both rotational speed and forearm muscle contraction level.

Takanori Uchiyama - One of the best experts on this subject based on the ideXlab platform.

  • static torque angle relation of human Elbow Joint estimated with artificial neural network technique
    Journal of Biomechanics, 1998
    Co-Authors: Takanori Uchiyama, Tomoyuki Bessho, Kenzo Akazawa
    Abstract:

    Abstract Static relations between Elbow Joint angle and torque at constant muscle activity in normal volunteers were investigated with the aid of an artificial neural network technique. A subject sat on a chair and moved his upper- and forearm in a horizontal plane at the height of his shoulder. The subject was instructed to maintain the Elbow Joint at a pre-determined angle. The wrist was then pulled to extend the Elbow Joint by the gravitational force of a weight hanging from a pulley. Integrated electromyograms (IEMGs), Elbow and shoulder Joint angles and Elbow Joint torque were measured. Then the relation among IEMGs, Joint angles and torque was modeled with the aid of the artificial neural network, where IEMGs and Joint angles were the inputs and torque was the output. After back propagation learning, we presented various combinations of IEMGs, shoulder and Elbow Joint angles to the model and estimated the Elbow Joint torque to obtain the torque–angle relation for constant muscle activation. The Elbow Joint torque increased and then decreased with extension of the Elbow Joint. This suggests that if the forearm is displaced from an equilibrium point, the torque–angle relation would not act like a simple spring. In a view of the musculoskeletal structure of the Elbow Joint, the relation between the Elbow Joint angle and the moment arm of the Elbow flexor muscles seems to have a dominant effect on the torque–angle relation.