The contribution of the anterior cruciate ligament to knee joint kinematics: Evaluation of its in situ forces using a robot/universal force-moment sensor test system

Muscle dynamics analysis by clustered categories during jogging in patients with anterior cruciate ligament deficiency

BACKGROUND

Patients with anterior cruciate ligament (ACL) deficiency (ACLD) tend to have altered lower extremity dynamics. Little is known about the changes in dynamic function and activation during jogging in patients with ACLD.

METHODS

Twenty patients with an injured ACL before ACL reconstruction (ACLD group) and nine healthy male volunteers (control group) were recruited. Each volunteer repeated the jogging experiment five times. Based on the experimental data measured, a musculoskeletal multibody dynamics model was employed to simulate the tibiofemoral joint dynamics during jogging. Eighteen muscles were used for analysis. The obtained dynamics data were used for clustering and curve difference analysis.

RESULTS

The 18 muscles studied were divided into 3 categories. All the quadriceps, the soleus, the gastrocnemius, and the popliteus were classified as label 1. All the hamstrings were classified as label 2, and the sartorius muscles were classified as label 3. Among them, the classification of the short head of the biceps femoris was significantly different between the two groups (P < 0.001). The force curves of all 18 muscles and the between-group differences were studied according to clustered categories. Most muscle force in label 1 was approaching zero in the terminal stance phase, which was significantly lower than that in the control group (P < 0.05). The muscle force in label 2 had areas with significant differences in the stance phase. Muscle force in label 3 was significantly lower than that in the control group in the pre-swing phase.

CONCLUSIONS

This study showed that there are various changes of muscle function and activation in patients with ACLD. Through clustering and curve analysis, the joint reactions and changes of different muscle forces in the gait cycle between the ACLD and control groups could be further clarified.

Leveraging Multivariable Linear Regression Analysis to Identify Patients with Anterior Cruciate Ligament Deficiency Using a Composite Index of the Knee Flexion and Muscle Force

Patients with anterior cruciate ligament (ACL) deficiency (ACLD) tend to have altered lower extremity kinematics and dynamics. Clinical diagnosis of ACLD requires more objective and convenient evaluation criteria. Twenty-five patients with ACLD before ACL reconstruction and nine healthy volunteers were recruited. Five experimental jogging data sets of each participant were collected and calculated using a musculoskeletal model. The resulting knee flexion and muscle force data were analyzed using a t-test for characteristic points, which were the time points in the gait cycle when the most significant difference between the two groups was observed. The data of the characteristic points were processed with principal component analysis to generate a composite index for multivariable linear regression. The accuracy rate of the regression model in diagnosing patients with ACLD was 81.4%. This study demonstrates that the multivariable linear regression model and composite index can be used to diagnose patients with ACLD. The composite index and characteristic points can be clinically objective and can be used to extract effective information quickly and conveniently.

Development of the concepts of knee kinematics

OBJECTIVES

To review the experimental evidence and development of concepts in knee kinematics and to present a synthesis of current theories.

DATA SOURCES

Historical literature from private collections and published journals, from Galen in 160 AD, and Weber and Weber in 1860, through to current research in knee kinematics, sourced through MEDLINE and CINAHL.

STUDY SELECTION

Studies of the healthy human knee in vivo and in vitro were included. Other studies were included when relevant, for example, when knee surgery methods have led to a change in kinematic concepts. Of 285 items, 94 were included based on their contribution to original research. When relevant, authors were contacted to resolve issues.

DATA EXTRACTION

Sources included were descriptive studies, anatomic dissections, controlled experimental designs, editorials, and review articles.

DATA SYNTHESIS

The axes of rotation of the knee are fundamental to kinematic models. The hinge model is contradicted by the ellipsoid shape of the femoral condyles, which results in a moving instant center of motion. However, the "instant center of motion" model was based on analysis of sagittal sections, oblique to the plane of movement and neglecting rotation. The four-bar linkage theory linked cruciate ligament isometry with the roll and glide pattern of knee motion. Recently, however, studies of the biomechanics and histology of the knee ligaments have enabled more accurate kinematic modeling. Three-dimensional imaging and computer modeling have made possible analysis of kinematics parallel to the planes of motion and incorporation of conjoint rotation. Femoral roll back is now described as the manifestation of longitudinal rotation during knee flexion.

CONCLUSIONS

Current research concludes that the knee has 4 independent axes: patella, posterior condylar, distal condylar, and longitudinal axes. The axes combine to produce the characteristic helical motion of the knee.

Current trends in anterior cruciate ligament reconstruction. Part 1: Biology and biomechanics of reconstruction

With today's increasing emphasis on sporting activities, the incidence of anterior cruciate ligament injuries has also increased. Epidemiologic studies estimate that the prevalence of anterior cruciate ligament injuries is about 1 per 3000 Americans. Management of these injuries has evolved from nonoperative treatment to extracapsular augmentation and primary ligament repair to anterior cruciate ligament reconstruction. Treatment of these injuries has significantly improved over the last few decades with the application of knowledge gained from both basic science and clinical research. This article is composed of two parts. The first part reviews the biology and biomechanics of the injured anterior cruciate ligament and the basic science of reconstruction. In the second part, to be published later, current operative concepts of reconstruction, as well as clinical correlations, are reviewed. Summarizing the latest information on basic scientific as well as clinical studies regarding the anterior cruciate ligament, this article intends to demonstrate the correlation between the application of basic science knowledge and improvement of clinical outcomes.