Peter K. Larsen

Nordic Walking does not reduce the loading of the knee joint

The use of Nordic Walking (NW) as a rehabilitation modality has increased considerably. NW (walking with poles) is advocated as a healthy physical activity that reduces the load on the knees. Few studies using the techniques of NW exist, and the findings are contradictory. The aim of this study was to investigate whether NW reduces the loadings upon the knee joint compared with walking without poles (NP). Seven experienced female NW instructors volunteered. Three‐dimensional gait analyses were performed. Internal flexor and extensor joint moments were calculated using an inverse dynamics approach and the knee joint compressive forces were calculated. No differences in compression or shear forces between NW and NP were found. The peak knee flexion angles were larger during NW (−32.5±6.0°) compared with NP (−28.2±4.2°). The hip range of motion (ROM) was significantly increased during NW (64.4±10.2°) compared with NP (57.8±9.7°); no differences in the knee and ankle joint ROM were observed. The changes in the joint angles were not followed by changes in the joint dynamics. The present study does not support the statement that NW reduces the load on the knees.

Biomechanical analysis of rollator walking

BackgroundThe rollator is a very popular walking aid. However, knowledge about how a rollator affects the walking patterns is limited. Thus, the purpose of the study was to investigate the biomechanical effects of walking with and without a rollator on the walking pattern in healthy subjects.MethodsThe walking pattern during walking with and without rollator was analyzed using a three-dimensional inverse dynamics method. Sagittal joint dynamics and kinematics of the ankle, knee and hip were calculated. In addition, hip joint dynamics and kinematics in the frontal plane were calculated. Seven healthy women participated in the study.ResultsThe hip was more flexed while the knee and ankle joints were less flexed/dorsiflexed during rollator walking. The ROM of the ankle and knee joints was reduced during rollator-walking. Rollator-walking caused a reduction in the knee extensor moment by 50% when compared to normal walking. The ankle plantarflexor and hip abductor moments were smaller when walking with a rollator. In contrast, the angular impulse of the hip extensors was significantly increased during rollator-walking.ConclusionWalking with a rollator unloaded the ankle and especially the knee extensors, increased the hip flexion and thus the contribution of hip extensors to produce movement. Thus, rollator walking did not result in an overall unloading of the muscles and joints of the lower extremities. However, the long-term effect of rollator walking is unknown and further investigation in this field is needed.

Variability and Similarity of Gait as Evaluated by Joint Angles: Implications for Forensic Gait Analysis

Closed‐circuit television (CCTV) footage is used in criminal investigations to compare perpetrators with suspects. Usually, incomplete gait cycles are collected, making evidential gait analysis challenging. This study aimed to analyze the discriminatory power of joint angles throughout a gait cycle. Six sets from 12 men were collected. For each man, a variability range VR (mean ± 1SD) of a specific joint angle at a specific time point (a gait cycle was 100 time points) was calculated. In turn, each individual was compared with the 11 others, and whenever 1 of these 11 had a value within this individuals VR, it counted as positive. By adding the positives throughout the gait cycle, we created simple bar graphs; tall bars indicated a small discriminatory power, short bars indicated a larger one. The highest discriminatory power was at time points 60–80 in the gait cycle. We show how our data can assess gait data from an actual case.

Gait as evidence

This study examines what in Denmark may constitute evidence based on forensic anthropological gait analyses, in the sense of pointing to a match (or not) between a perpetrator and a suspect, based on video and photographic imagery. Gait and anthropometric measures can be used when direct facial comparison is not possible because of perpetrators masking their faces. The nature of judicial and natural scientific forms of evidence is discussed, and rulings dealing with the admissibility of video footage and forensic evidence in general are given. Technical issues of video materials are discussed, and the study also discusses how such evidence may be presented, both in written statements and in court.

Gait analysis of adults with generalised joint hypermobility.

BACKGROUND The majority of adults with Generalised Joint Hypermobility experience symptoms such as pain and joint instability, which is likely to influence their gait pattern. Accordingly, the purpose of the present project was to perform a biomechanical gait analysis on a group of patients with Generalised Joint Hypermobility and compare them to a group of healthy subjects. METHODS Seventeen adults clinically classified with Generalised Joint Hypermobility (6 males and 11 females) and seventeen healthy subjects (9 males and 8 females) were included in the project. The subjects walked across three force platforms while they were filmed by five video cameras. Net joint moments were calculated in 3D by inverse dynamics and peak values were input to statistical analyses. A 3D knee joint model was used to calculate bone-on-bone forces. FINDINGS In the frontal plane both the peak knee and hip abductor moments were 13% higher in the patient group. In the sagittal plane the peak knee extensor moment was 10% higher for the patients and the flexor moment about the knee joint in the middle of stance was 27% lower for the patients. Increased flexion in the knee joint for the patients was also observed. INTERPRETATION The finding that adults with Generalised Joint Hypermobility display higher joint moments during walking in both the frontal and the sagittal planes and increased knee joint loadings may explain the pain symptoms in the patient group and indicate these subjects are subjected to an increased risk of developing osteo-arthritis.

Variability of Bodily Measures of Normally Dressed People Using PhotoModeler® Pro 5*

Abstract:  Photogrammetry is used in forensic science to help identify perpetrators from crime scenes by way of surveillance video, but the reproducibility of manually locating hidden body‐points such as the joints remains to be established. In this study, we quantified the inter‐ and intra‐observer variability of bodily measures of clothed individuals in two different poses and examined whether body segment lengths could be used to distinguish between people of similar stature. Stature was reproduced within ±1.5 cm in both the intra‐ and inter‐observer study. Segment lengths were best reproduced when flexion in the joints was present in the intra‐observer study, but only the length of the trunk could be used to distinguish between people of similar height. The reproducibility between the two poses was low. Other measures than stature should be used with caution and with the perpetrator and suspect in the same pose. Consistent guidelines for locating body‐points should be developed.

Dynamic balance during gait in children and adults with Generalized Joint Hypermobility.

BACKGROUND The purpose of the study was to investigate if differences of the head and trunk stability and stabilization strategies exist between subjects classified with Generalized Joint Hypermobility and healthy controls during gait. It was hypothesized that joint hypermobility could lead to decreased head and trunk stability and a head stabilization strategy similar to what have been observed in individuals with decreased locomotor performance. METHODS A comparative study design was used wherein 19 hypermobile children were compared to 19 control children, and 18 hypermobile adults were compared to 18 control adults. The subjects were tested during normal walking and walking on a line. Kinematics of head, shoulder, spine and pelvis rotations were measured by five digital video cameras in order to assess the segmental stability (angular dispersion) and stabilization strategies (anchoring index) in two rotational components: roll and yaw. FINDINGS Hypermobile children and adults showed decreased lateral trunk stability in both walking conditions. In hypermobile children, it was accompanied with decreased head stability as the head was stabilized by the inferior segment when walking on a line. Several additional differences were observed in stability and stabilization strategies for both children and adults. INTERPRETATION Stability of the trunk was decreased in hypermobile children and adults. This may be a consequence of decreased stability of the head. Hypermobile children showed a different mode of head stabilization during more demanding locomotor conditions indicating delayed locomotor development. The findings reflect that Generalized Joint Hypermobility probably include motor control deficits.

Gait analysis in forensic medicine

We have combined the basic human ability to recognize other individuals with functional anatomical and biomechanical knowledge, in order to analyze the gait of perpetrators as recorded on surveillance video. The perpetrators are then compared with similar analyses of suspects. At present we give a statement to the police as to whether the perpetrator has a characteristic gait pattern compared to normal gait, and if a suspect has a comparable gait pattern. We have found agreements such as: limping, varus instability in the knee at heel strike, larger lateral flexion of the spinal column to one side than the other, inverted ankle during stance, pronounced sagittal head-movements, and marked head-shoulder posture. Based on these characteristic features, we state whether suspect and perpetrator could have the same identity but it is not possible to positively identify the perpetrator. Nevertheless, we have been involved in several cases where the court has found that this type of gait analysis, especially combined with photogrammetry, was a valuable tool. The primary requisites are surveillance cameras recording with sufficient frequency, ideally about 15 Hz, which are positioned in frontal and preferably also in profile view.

Gait pattern in 9-11-year-old children with generalized joint hypermobility compared with controls; a cross-sectional study

BackgroundTo study differences in gait patterns in 10-year-old children with Generalized Joint Hypermobility (GJH) and with no GJH (NGJH).MethodsA total of 37 children participated (19 GJH, 18 NGJH, mean age 10.2 (SD 0.5) years). Inclusion criteria for GJH were a Beighton score of ≥5, with at least one hypermobile knee joint; for NGJH a Beighton score of ≤4, and no hypermobile knees and for both groups no knee pain during the previous week. All children were recorded by five video cameras, while they walked across three force platforms. Net joint moments were calculated in 3D by inverse dynamics and peak values provided input to statistical analyses.ResultsIn the frontal plane, children with GJH had a significantly lower peak knee abductor moment and peak hip abductor moment. In the sagittal plane, the peak knee flexor moment and the peak hip extensor moment were significantly lower in the GJH group although the absolute difference was small.ConclusionsThe walking pattern was the same for children with GJH and for healthy children, as there were no differences in kinematics, but it was, however, performed with different kinetics. Children with GJH walked with lower ankle, knee and hip joint moments compared to children with NGJH. However, the clinical importance of these differences during normal gait is unknown. To obtain this knowledge, children with GJH must be followed longitudinally.Trial registrationThe study was approved by the Committee on Biomedical Research Ethics for Copenhagen and Frederiksberg, Denmark (jnr. KF01-2006-178).

Markerless motion capture systems for tracking of persons in forensic biomechanics: an overview

Markerless motion capture is a pronounced topic in computer vision. In forensic science, markerless motion capture can be an important tool for identification through gait analysis. Recent studies of gait analysis in forensic science have shown that individuals can be identified when analysing the postures from a sagittal viewpoint. Although integrating all three dimensions (3D) might improve the results considerably. The purpose of this paper is to give an overview of the 3D multi-view markerless motion capture systems which could be applicable for 3D gait analysis. This paper contains presentation of the state of the art in obtaining 3D poses from multi-camera configurations and discussion of the cons and pros of the approaches.