Redistribution of joint moments during walking in patients with drop-foot

Background

The purpose of the study was to analyze the distribution of net joint moments in the lower extremities in patients walking with a drop-foot compared to a group of healthy subjects. A drop-foot causes the patient to walk with a characteristic limp and it was hypothesized that the drop-foot could lead to increased loadings of one or more joints.

Methods

Six patients and fourteen healthy subjects walked at a fixed speed over two recessed force platforms while the movements were recorded by six infrared cameras. Net joint moments were calculated by inverse dynamics.

Findings

The patients showed an almost doubled peak knee extensor moment during the stance phase compared to healthy subjects. This was accompanied by an increased knee joint flexion. The increased extensor moment about the knee joint was found in both the affected and unaffected leg of the patients. This was accompanied by increased maximal knee joint flexion in both legs of the patients compared to the healthy subjects. Several additional differences were observed in joint moments and joint angles between the two groups and between the two legs of the patients.

Interpretation

The increased knee joint extensor moment leads to increased joint loading, which potentially may lead to development of osteo-arthritis over the years. It is recommended that patients with a drop-foot are offered an ankle joint orthosis in an attempt to restore normal function of the ankle joint, which will most likely reduce the knee joint loadings.     

Taylor空间外固定架联合胫骨高位截骨术对膝骨性关节炎并膝内翻患者膝关节功能的影响

目的 探讨分析Taylor空间外固定架联合胫骨高位截骨术(HTO)在膝骨性关节炎并膝内翻患者中的应用.方法 回顾性选取2018年3月至2020年12月唐山市开滦总医院接受治疗的40例膝骨性关节炎并膝内翻患者,按照治疗方法不同分为2组,各20例.观察组患者采用Taylor外固定,对照组患者采用钢板内固定,2组均行HTO....     

Comparison of distinctive gait variables using two different biomechanical models for knee joint kinematics in subjects with knee osteoarthritis and healthy controls

Background

Gait analysis is an important instrument in clinical research and results should be objective. The purpose of this study was to quantify clinical outcomes of two biomechanical models with different anatomical coordinate systems and angle decomposition strategies for knee joint kinematics.

Methods

The study was designed to compare a functional approach and a predictive approach with a single comprehensive marker set. 10 healthy subjects and 12 subjects with knee osteoarthritis were analysed. Distinctive gait variables were averaged across five trials. Agreement between methods was illustrated with the so-called levels of agreement. Differences between models were quantified using a paired t-test or Wilcoxon-Signed Rank test in case of non-normality (Shapiro–Wilk test). Unpaired t-tests/Wilcoxon tests were used to compare gait variables between healthy subjects and subjects with knee osteoarthritis, and to examine whether statistical analysis of this comparison would yield different data interpretations when using different models.

Findings

Outcome variables differed between the functional and predictive approaches in the sagittal plane (0.1–3.1°), and transverse plane (1.0–3.7°). With respect to the range of motion in the given movement plane, variables in the sagittal plane of the knee were more consistent between methods. The functional approach was more sensitive for detecting differences between groups for sagittal plane kinematics. Statistical analysis for transverse plane kinematics differed substantially between models.

Interpretation

Sensitivity to detect differences of kinematic data between population groups can vary between biomechanical models. Rotational gait variables are inconsistent between models and should not be used as clinical outcome variables in daily routine.     

The influence of cyclic concentric and eccentric submaximal muscle loading on cell viability in the rabbit knee joint

Background

Cartilage loading is associated with the onset and progression of osteoarthritis and cell death may play an important role in these processes. Although much is known about cell death in joint impact loading, there is no information on joints loaded by muscular contractions. The aim of this study was to evaluate the influence of muscle generated eccentric and concentric submaximal joint loading on chondrocyte viability. We hypothesised that eccentric muscle activation leads to increased cell death rates compared to concentric loading and to controls.

Methods

16 rabbits received either 50 min of uni-lateral, cyclic eccentric (n = 8) or concentric (n = 8) knee loading. Muscle activation for these dynamic conditions was equivalent to an activation level that produced 20% of maximum isometric force. Contralateral joints served as unloaded controls. Cell viability was assessed using confocal microscopy.

Findings

Eccentric contractions produced greater knee loading than concentric contractions. Sub-maximal contractions caused a significant increase in cell death in the loaded knees compared to the unloaded controls, and eccentric loading caused significantly more cell death than concentric loading.

Interpretation

Cyclic sub-maximal muscle loading of the knee caused increased chondrocyte death in rabbits. These findings suggest that low levels of joint loading for prolonged periods, as occurs in endurance exercise or physical labour, may cause chondrocyte death, thereby predisposing joints to degeneration.