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Passive resistance of the knee after anterior cruciate ligament reconstruction
540
Abstracts of the Fourth Meeting of the European Society of Biomechanics THE BIOMECHANICS
OF KNEE LIGAMENTS
L. E. CLAESand R. K. SCHMID (University of Ulm, Department of Surgery, Oberer Eselsberg, D-79 Ulm, F.R.G.) For the post-operative treatment of acute ligament injuries as well as for prosthetic ligament reconstruction the knowledge of knee ligament biomechanics is necessary. To determine the stress and strain in knee ligaments special measuring cells and a knee simulator were developed. Six cadaver knee joints fixed in this simulator were flexed with a constant rate of motion between 0 and 130” of flexion by a motor. The testmachine allows the simulation of abductional, adductional, internal- and external-rotational movements as well as muscle forces. All ligaments showed their maximum stress and strain between 0 and 30” of flexion. The strain in the collateral ligaments was about five times that of the strain in the cruciate ligaments. The ventral and dorsal parts of the broad MCL showed contrary behaviour. Stress and strain were not proportional, i.e. the largest strain but the lowest tensile force was measured at the dorsal part of the MCL. The highest strain under pure flexion was 5 %, and the largest tensile force was about 20 N. Twenty-two different load combinations were measured. Valgus, varus and rotational loads increased the stress and strain in specific ligaments. EXPERIMENTAL
ROTATORY
INSTABILITY
OF THE KNEE JOINT
STRANGENIELSEN,J. OVESEN,0. RASMUSSENand K. ANDERSEN(Biomechanics Laboratory, Orthopaedic Hospital, Aarhus, Denmark) The importance of the anterior cruciate ligament (ACL) and the medial and lateral compartment ligaments of the knee in relation to valgus-varus and axial rotation instability was investigated on 30 osteoligamentous preparations. Registration of instability was done continuously in the extension-flexion movement during a constant torque submitted to the tibia. Isolated injury to the collateral medial or lateral ligaments did not cause any major valgus or varus instability, but when also the posterior capsule was damaged, a considerable degree of rotatory instability was found even though the cruciate ligaments were intact. The posterior medial capsule was in relation to the ACL the most important stabilizer concerning external rotation second to the medial collateral ligament. Registration of pivot shift meant damage to the ACL. EXPERIMENTAL
ANTERIOR
INSTABILITY
OF THE GLENOHUMERAL
JOINT
J. OVESEN,S. NIELSENand I. HVID (Biomechanics Laboratory, Orthopaedic Hospital, Aarhus, Denmark) In ten osteoligamentous preparations the increment in external rotation of the glenohumeral joint was measured, when the humerus was abducted with a constant external torque of 1.5 Nm, and the anterior stabilizing structures were cut in sequence. It was found that them. subscapularis stabilizes the joint in the lower range ofabduction. As abduction further increased, the stabilizing function of the capsule is shifted from the superior to the inferior part of the capsule.
PASSIVE RESISTANCE
OF THE KNEE AETER ANTERIOR RECONSTRUCTION
CRUCIATE
LIGAMENT
Y. HEERKENS,P. HUIJING, G. VANINGEN SCHENAU,R. WOITTIEZ and R. ROZENDAL(Interfaculty of Physical Education, Free University, Amsterdam, The Netherlands) Passive resistance of the knee of twelve patients was determined with an arthrograph, imposing sinusoidal excursions in the flexion-extension plane, 3-8 months after surgery. Centre torques of the torque angle diagrams showed an increased resistance to flexion for the affected knee (141% of the contralateral torque at an angle of 90’) and a decreased resistance to extension (66 % at 15’). The loss of mechanical energy (area of the diagrams) was lower both in extension (74 7;) as well as in flexion (94%). The higher resistance to flexion may be due to shortening of the quadriceps muscle, and/or a shorter and more ventrally inserted ligament. The lower resistance to extension and the lower energy loss may be due to atrophy. ANTERIOR-POSTERIOR
KNEE INSTABILITY AND STRESS RADIOGRAPHY: A BIOMECHANICAL ANALYSIS
H. U. ST~~UBLI,R. P. JAKOBand B. NOESBERGER(Orthopaedic Clinic, University of Berne, CH-3010 Berne, Switzerland) In a prospective, stress-radiographical analysis, the relative anterior and posterior femoro-tibia1 displacements were compared to the status of the anterior and posterior cruciate ligaments (ACL, PCL). The status of the cruciate ligaments was documented by functional hook-probing during arthrotomy or arthroscopy under anaesthesia in 10” of knee flexion. In 77 complete ACL-tears (PCL intact) a significant anterior tibia1 displacement (p < 0.01) was determined as
Abstracts of the Fourth Meeting of the European Society of Biomechanics THE BIOMECHANICS
OF KNEE LIGAMENTS
L. E. CLAESand R. K. SCHMID (University of Ulm, Department of Surgery, Oberer Eselsberg, D-79 Ulm, F.R.G.) For the post-operative treatment of acute ligament injuries as well as for prosthetic ligament reconstruction the knowledge of knee ligament biomechanics is necessary. To determine the stress and strain in knee ligaments special measuring cells and a knee simulator were developed. Six cadaver knee joints fixed in this simulator were flexed with a constant rate of motion between 0 and 130” of flexion by a motor. The testmachine allows the simulation of abductional, adductional, internal- and external-rotational movements as well as muscle forces. All ligaments showed their maximum stress and strain between 0 and 30” of flexion. The strain in the collateral ligaments was about five times that of the strain in the cruciate ligaments. The ventral and dorsal parts of the broad MCL showed contrary behaviour. Stress and strain were not proportional, i.e. the largest strain but the lowest tensile force was measured at the dorsal part of the MCL. The highest strain under pure flexion was 5 %, and the largest tensile force was about 20 N. Twenty-two different load combinations were measured. Valgus, varus and rotational loads increased the stress and strain in specific ligaments. EXPERIMENTAL
ROTATORY
INSTABILITY
OF THE KNEE JOINT
STRANGENIELSEN,J. OVESEN,0. RASMUSSENand K. ANDERSEN(Biomechanics Laboratory, Orthopaedic Hospital, Aarhus, Denmark) The importance of the anterior cruciate ligament (ACL) and the medial and lateral compartment ligaments of the knee in relation to valgus-varus and axial rotation instability was investigated on 30 osteoligamentous preparations. Registration of instability was done continuously in the extension-flexion movement during a constant torque submitted to the tibia. Isolated injury to the collateral medial or lateral ligaments did not cause any major valgus or varus instability, but when also the posterior capsule was damaged, a considerable degree of rotatory instability was found even though the cruciate ligaments were intact. The posterior medial capsule was in relation to the ACL the most important stabilizer concerning external rotation second to the medial collateral ligament. Registration of pivot shift meant damage to the ACL. EXPERIMENTAL
ANTERIOR
INSTABILITY
OF THE GLENOHUMERAL
JOINT
J. OVESEN,S. NIELSENand I. HVID (Biomechanics Laboratory, Orthopaedic Hospital, Aarhus, Denmark) In ten osteoligamentous preparations the increment in external rotation of the glenohumeral joint was measured, when the humerus was abducted with a constant external torque of 1.5 Nm, and the anterior stabilizing structures were cut in sequence. It was found that them. subscapularis stabilizes the joint in the lower range ofabduction. As abduction further increased, the stabilizing function of the capsule is shifted from the superior to the inferior part of the capsule.
PASSIVE RESISTANCE
OF THE KNEE AETER ANTERIOR RECONSTRUCTION
CRUCIATE
LIGAMENT
Y. HEERKENS,P. HUIJING, G. VANINGEN SCHENAU,R. WOITTIEZ and R. ROZENDAL(Interfaculty of Physical Education, Free University, Amsterdam, The Netherlands) Passive resistance of the knee of twelve patients was determined with an arthrograph, imposing sinusoidal excursions in the flexion-extension plane, 3-8 months after surgery. Centre torques of the torque angle diagrams showed an increased resistance to flexion for the affected knee (141% of the contralateral torque at an angle of 90’) and a decreased resistance to extension (66 % at 15’). The loss of mechanical energy (area of the diagrams) was lower both in extension (74 7;) as well as in flexion (94%). The higher resistance to flexion may be due to shortening of the quadriceps muscle, and/or a shorter and more ventrally inserted ligament. The lower resistance to extension and the lower energy loss may be due to atrophy. ANTERIOR-POSTERIOR
KNEE INSTABILITY AND STRESS RADIOGRAPHY: A BIOMECHANICAL ANALYSIS
H. U. ST~~UBLI,R. P. JAKOBand B. NOESBERGER(Orthopaedic Clinic, University of Berne, CH-3010 Berne, Switzerland) In a prospective, stress-radiographical analysis, the relative anterior and posterior femoro-tibia1 displacements were compared to the status of the anterior and posterior cruciate ligaments (ACL, PCL). The status of the cruciate ligaments was documented by functional hook-probing during arthrotomy or arthroscopy under anaesthesia in 10” of knee flexion. In 77 complete ACL-tears (PCL intact) a significant anterior tibia1 displacement (p < 0.01) was determined as