Effect of Unilateral Knee Extension Restriction on the Lumbar Region during Gait.

Unilateral knee extension restriction might change trunk alignment and increase mechanical load on the lumbar region during walking. We aimed to clarify lumbar region mechanical load during walking with restricted knee extension using a musculoskeletal model simulation. Seventeen healthy adult males were enrolled in this study. Participants walked 10 m at a comfortable velocity with and without restricted right knee extension of 15° and 30° using a knee brace. L4-5 joint moment, joint reaction force, and muscle forces around the lumbar region during walking were calculated for each condition. Peaks of kinetic data were compared among three gait conditions during 0%-30% and 50%-80% of the right gait cycle. Lumbar extension moment at early stance of the bilateral lower limbs was significantly increased in the 30° restricted condition (p ≤ 0.021). Muscle force of the multifidus showed peaks at stance phase of the contralateral side during walking, and the erector spinae showed force peaks at early stance of the bilateral lower limb. Muscle force of the multifidus and erector spinae increased with increasing degree of knee flexion (p ≤ 0.010), with a large effect size (η 2 = 0.273-0.486). The joint force acting on L4-5 showed two peaks at early stance of the bilateral lower limbs during the walking cycle. The anterior and vertical joint force on L4-5 increased by 14.2%-36.5% and 10.0%-23.0% in walking with restricted knee extension, respectively (p ≤ 0.010), with a large effect size (η 2 = 0.149-0.425). Restricted knee joint extension changed trunk alignment and increased the muscle force and the vertical and anterior joint force on the L4-5 joint during walking; this tendency became more obvious with increased restriction angle. Our results provide important information for therapists engaged in the rehabilitation of patients with knee contracture.

Contribution of hip and knee muscles to lateral knee stability during gait.

[Purpose] Lateral knee instability is frequently observed in patients with knee injury or risk factors associated with knee osteoarthritis. Physical exercises can strengthen muscles that stabilize the knee joint. The purpose of this study was to define the contribution of the knee and hip muscles to lateral knee stability by comparing the muscle forces, as assessed by musculoskeletal simulation using one or two degrees-of-freedom (1-DOF and 2-DOF) knee models. [Participants and Methods] We evaluated the normal gait of 15 healthy subjects. We conducted a three-dimensional gait analysis using a motion analysis system and a force plate. We considered a muscle as a lateral knee stabilizer when the calculated muscle force was greater with the 2-DOF model than with the 1-DOF model. [Results] During early and late stance, the muscle forces of the lateral knee and hip joint increased in the 2-DOF model as opposed to in the 1-DOF model. In contrast, the forces of the medial knee muscles decreased. Furthermore, hip muscle forces increased during the late stance. [Conclusion] Our results show that the lateral knee and hip muscles contribute to lateral knee stability. Thus, exercises to strengthen these muscles could improve lateral knee stability.

Effectiveness of simple tracing test as an objective evaluation of hand dexterity.

This study aimed to demonstrate that the simple tracing test (STT) is useful for assessing the hand dexterity in patients with cervical spondylotic myelopathy (CSM) by comparing STT scores between healthy volunteers and CSM patients. This study included 25 CSM patients and 38 healthy volunteers. In the STT, the participants traced a sine wave displayed on a tablet device at a comfortable pace, and the tracing accuracy, changes in the total sum of pen pressures, and tracing duration were assessed. Data were analyzed using an artificial neural networks (ANN) model to obtain STT scores. All participants were evaluated using the subsection for the upper extremity function of the Japanese Orthopaedic Association (JOA) scoring system for cervical myelopathy (JOA subscore for upper extremity function) and the grip and release test (GRT). The results were compared with the STT scores. The mean STT scores were 24.4 ± 32.8 in the CSM patients and 84.9 ± 31.3 in the healthy volunteers, showing a significant difference. The STT scores showed highly positive correlations with both the JOA subscore for upper extremity function (r = 0.66; P < 0.001) and GRT values (r = 0.74; P < 0.001). Furthermore, receiver operating characteristic analysis showed an area under the curve of 0.89 (95% confidence interval, 0.76-1.00), demonstrating that STT has excellent discriminative ability. This study revealed that STT enables accurate assessment of the hand dexterity in CSM patients.

Biomechanical characterization of slope walking using musculoskeletal model simulation.

PURPOSE: Upslope and downslope walking are basic activities necessary for normal daily living in community, and they impose greater joint load on the lower extremities than during level walking. Thus, the purpose of this study was to quantify the resultant and shear forces in the hip and knee joints during slope walking. METHODS: Twelve healthy volunteers were evaluated when walking under level and 10° up- and downslope conditions. Three-dimensional gait analysis was conducted using a 7-camera optoelectronic motion analysis system combined with a force plate to measure ground reactive force. Joint forces in the hip and knee joints were estimated using musculoskeletal model simulation. RESULTS: Results showed that the resultant hip force was increased significantly to 117.2% and 126.9%, and the resultant knee force was increased to 133.5% and 144.5% in up- and downslope walking, respectively, compared to that of level walking. Furthermore, increased shear force in the hip and knee joints was noted during both slope walking conditions. CONCLUSIONS: This information may be beneficial for therapists advising elderly people or patients with osteoarthrosis on an appropriate gait pattern, gait assistive devices, or orthoses according to their living environment.