End Of Flexion Research Articles

Intraoperative sensor technology quantifies inter-prosthesis pressure for predicting lower limb alignment after Oxford unicompartmental knee arthroplasty.

Purpose: The aim of this study is to quantify inter-prosthetic pressures at different knee angles in Oxford unicompartmental knee arthroplasty (OUKA) and its correlation with postoperative lower limb alignment. Methods: This study included 101 patients (122 knees) who underwent OUKA from March 2022 to July 2022. The previously designed matrix flexible force sensor was used to measure the inter-prosthesis pressure of different knee joint angles during the UKA operation, and the force variation trend and gap balance difference were obtained. The correlation between inter-prosthesis pressure and postoperative lower limb alignment index including hip-knee-ankle angle (HKAA) and posterior tibial slope (PTS) was analyzed. The effect of PTS change (ΔPTS) on the inter-prosthesis pressure and the range of motion (ROM) of the knee joint was analyzed. Radiographic and short-term clinical outcomes of included patients were assessed. Results: The inter-prosthesis pressure of the different knee joint angles during the operation was not consistent. The mean inter-prosthesis pressure and gap balance difference were 73.68.28 ± 41.65N and 36.48 ± 20.58N. The inter-prosthesis pressure at 0° and 20° was positively correlated with postoperative HKAA (p < 0.001). ΔPTS was positively correlated with the pressure at the end of knee extension and negatively correlated with the pressure at the end of knee flexion (p < 0.001). The HKAA, ROM, degree of fixed knee flexion deformity, and knee society score of the included patients were significantly improved compared with those before the operation (p < 0.001). Conclusion: The inter-prosthesis pressure measured at the knee extension position can predict postoperative HKAA to some degree. Changes in PTS will affect the inter-prosthesis pressure at the end of flexion and end of knee extension, but this change is not related to the range of motion of the knee joint.

Abnormal Patterns of Biceps and Triceps Co-Contraction Following Elbow Surgery May Result in Elbow Stiffness.

This study examines the pattern of muscular contraction and the intensity of this contraction of the biceps and triceps following elbow surgery. We performed a prospective electromyographic study of 16 patients undergoing 19 surgical procedures on the elbow joint. We measured the resting EMG signal intensity of the biceps and triceps of the operated and the normal sides at 90 degrees. We then calculated the peak EMG signal intensity during passive elbow flexion and extension of the operated side. Seventeen of 19 elbows (89%) displayed a co-contraction pattern of the biceps and triceps near the end of flexion and extension during the passive range of motion. The co-contraction pattern was observed near the end of the range of motion in both flexion and extension. In addition to the observed co-contraction patterns, we detected higher contraction intensities for the biceps and triceps muscles in all patients in both flexion and extension for the elbows, which had been treated surgically. Further analysis suggests an inverse correlation between the biceps contraction intensity and the arc of motion measured at the latest follow-up. The co-contraction pattern and increased contraction intensity of periarticular muscle groups may result in internal splinting mechanisms, contributing to the development of elbow joint stiffness, which is frequently observed following elbow surgery.

The Role of the Muscle Brachioradialis in Elbow Flexion: An Electromyographic Study.

In the classical conception, the brachioradialis is a forearm supinator. The hypothesis of this study was that, at least in certain positions of elbow flexion and forearm rotation, the brachioradialis is, along with the biceps and brachialis, one of the main elbow flexors. Fifteen young healthy male volunteers participated in this research. The activities of the biceps, brachialis and brachioradialis muscles were studied using surface electromyography, while the subjects were performing elbow flexions/extensions with as much strength as possible, forearm in neutral position, then in full pronation, then in full supination. The elbow flexion torques were isokinetically measured at 60°/sec for an arc of 120°. The biceps, brachialis and brachioradialis muscles were electromyographically very active throughout resisted elbow flexion, in all three investigated positions of forearm rotation. At certain positions, the electromyographic activities were much higher than the maximal voluntary contraction signal. For what concerns specifically the brachioradialis, in all three forearm rotation investigated positions, the activity curve demonstrated a slow increase during the first part of elbow flexion, reaching in 73.3% of subjects its peak at the end of flexion; in the remaining 26.7%, the brachioradialis had a flat activity without significant peak. The activity was slightly higher in supination. This study indirectly supports the idea that the brachioradialis is one of the main elbow flexors, especially when the elbow flexion is done with the forearm in supination. This observation could be important in clinical elbow and wrist surgical practice.

Analysis of muscle moment and reaction force of elbow joint during flexion movement

Since its coming of age in the mid 1960s, continuum biomechanics has contributed much to understanding of human health as well as to disease, injury, and their treatment. Nevertheless, biomechanics has yet to reach its full potential as a consistent contributor to the improvement of healthcare delivery. In this research elbow flexion has been analysed and the moment of muscles and the reaction force exerted on the elbow is calculated in the range of motion. The moment of muscles indicate the performance of movement and the reaction force of the joint is believed to be one of the most important causes of damage, something which has not been studied thoroughly enough in previous researches. The elbow joint has been modelled in CATIA software and we use ADAMS software for the analysis which is one of the most powerful ones available in dynamics analyses. The results indicate that the maximum torque of the arm occurs at 94 degrees and it decreases in the beginning and the end of flexion. The reaction force of the elbow in the beginning of motion is at maximum amount and then decreases to 100 degrees, and from that point on it increases up to the end of the motion. These results indicate that the optimum range of elbow flexion occurs in the mid-range of flexion, approximately at 60-140 degrees.

Analysis of muscle moment and reaction force of elbow joint during flexion movement

Since its coming of age in the mid 1960s, continuum biomechanics has contributed much to understanding of human health as well as to disease, injury, and their treatment. Nevertheless, biomechanics has yet to reach its full potential as a consistent contributor to the improvement of healthcare delivery. In this research elbow flexion has been analysed and the moment of muscles and the reaction force exerted on the elbow is calculated in the range of motion. The moment of muscles indicate the performance of movement and the reaction force of the joint is believed to be one of the most important causes of damage, something which has not been studied thoroughly enough in previous researches. The elbow joint has been modelled in CATIA software and we use ADAMS software for the analysis which is one of the most powerful ones available in dynamics analyses. The results indicate that the maximum torque of the arm occurs at 94 degrees and it decreases in the beginning and the end of flexion. The reaction force of the elbow in the beginning of motion is at maximum amount and then decreases to 100 degrees, and from that point on it increases up to the end of the motion. These results indicate that the optimum range of elbow flexion occurs in the mid-range of flexion, approximately at 60-140 degrees.

Back and hip extensor activities during trunk flexion/extension: Effects of low back pain and rehabilitation

Leinonen V, Kankaanpää M, Airaksinen O, Hänninen O. Back and hip extensor activities during trunk flexion/extension: effects of low back pain and rehabilitation. Arch Phys Med Rehabil 2000;81:32-7. Objective: To compare lumbar paraspinal, gluteus maximus, and biceps femoris muscle function during sagittal trunk flexion and extension in patients with chronic low back pain and healthy control subjects, and to assess the influence of rehabilitation in the back pain patients. Design: A cross-sectional study comparing chronic low back pain patients and healthy controls, and a prospective follow-up in back pain patients during rehabilitation. Setting: Physical medicine and rehabilitation clinic. Subjects: Nineteen women with chronic low back pain, and 19 women without pain (controls). Intervention: Five-week active outpatient rehabilitation (1 hour three times a week) guided by a physiotherapist, followed by 5-week self-motivated exercise at home. Outcome Measures: Subjects performed sagittal trunk flexion and extension while surface electromyogram was bilaterally recorded of paraspinal (L1-L2 level), gluteus maximus, and biceps femoris muscles. The muscle activity was assessed from the average electromyogram and the relative muscle activation onsets and their duration were calculated. Results: During early flexion, lumbar paraspinal and biceps femoris were activated simultaneously before gluteus maximus. At the end of flexion and during extension all investigated muscles were activated and relaxed in order. Lumbar paraspinal and biceps femoris muscles were activated in a similar order in low back pain patients and healthy controls during flexion and extension. However, the duration of gluteus maximus activity was shorter in the back pain patients than in controls during the trunk flexion (p < .05), and it ended earlier during extension. Active rehabilitation did not change the muscle activities of lumbar paraspinal and biceps femoris in the back pain patients, but in the measurements after rehabilitation the onset of gluteus maximus activity occurred later in flexion and earlier in extension. Conclusions: The activity of the gluteus maximus muscle during the flexion-extension cycle was reduced in patients with chronic low back pain. The gluteal muscles should be taken into consideration in the rehabilitation of these patients. © 2000 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation

Hopping and swimming in the leopard frog, Rana pipiens: I. Step cycles and kinematics.

This study presents a model for the step cycle patterns used during both hopping and swimming by the leopard frog, Rana pipiens. The two behaviors are essentially similar in movement pattern and in the ways they are modified from quadrupedal gaits. In hopping, there is marked hind limb extension throughout stance. The swing begins with a suspension equivalent to the leap that occurs in a galloping or bounding quadruped. Following suspension, as the frog descends from the apex of its leap, the hind limbs remain posterior and in line with the spine while they flex. Near the end of flexion, there is a rapid downward rotation of the hindquarters to bring the hind feet underneath the body. This movement utilizes the planted forelimb as a pivot. A similar pattern of movement occurs in swimming; the stance (propulsion) phase involves extension at all hind limb joints. The swing (recovery) phase begins with the hind feet fully extended and includes a protracted gliding phase, equivalent to the suspension in the hop. The hind limb then recovers to its initial position during a flexion phase. Since there is no landing and the hind limbs remain lateral rather than ventral to the pelvis, less flexion occurs in the spine or the limb joints. In both behaviors, the extensor muscles of hip (M. semimembranosus), knee (M. cruralis), and ankle (M. plantaris longus) achieve their longest lengths, when they likely can produce near maximal force, at the beginning of extension. All three muscles shorten during extension, but, because they are multiple-joint muscles, the amount of shortening is relatively small (approximately 15%). Hopping and swimming in frogs are comparable asymmetrical gaits with the same relative contact intervals (25% of stride). The step cycles in both gaits are modified from quadrupedal locomotion in the same ways: by 1) loss of knee and ankle extension toward the ground prior to landing (or end of flexion in swimming), 2) loss of a yield phase on landing (or end of flexion in swimming), and 3) inclusion of extended suspensions in both gaits.

Hip-spine movement interaction and muscle activation patterns during sagittal trunk movements in low back pain patients.

Profiles of hip-spine movement interaction and muscle activations were characterized in 10 low back pain patients and in 10 normal subjects during trunk forward bending and extension. Electrogoniometric recordings showed that patients performed the movements significantly more slowly than normal subjects when asked to choose a comfortable cadence. For movements performed at the same velocity and amplitude, only the movement profiles at the spine and activation patterns of the erector spinae (ES) muscle during flexion were found to be significantly different between the two groups. A detailed analysis revealed that a subgroup of six patients (SG2) with an abnormal hip-spine movement interaction showed a significant (P < 0.01) lack of relaxation in ES muscle at the end of flexion. Patients from SG2 had pain for a longer time (P < 0.01) compared to patients from SG1 with normal movement and electromyographic profiles. Given the small sample size, these results are not conclusive, but they suggest that the lack of relaxation of the ES muscle may be associated with perturbation of movement patterns and the duration of the symptoms.

Passive motion of the elbow joint

A previously unreported method of measuring three-dimensional motion of joints, applied to two elbows obtained post mortem, showed that during flexion there is a continuous and linear change in the carrying angle, the forearm going into varus angulation as elbow flexion progresses. In addition, internal axial rotation of the forearm occurs near the beginning and external axial rotation, toward the end of flexion. With the elbow extended, the ulna shows little tendency to deviate laterally or to rotate axially during pronation and supination. The axis of rotation during elbow flexion lies approximately at the center of the trochlea.