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Biomedical Engineering / Biomedizinische Technik, 52 (4), ISSN:0013-5585, ISSN:1862-278X

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.

Gait analysis is an important instrument to investigate foot and ankle biomechanics in the field of footwear design. Results of this method should be objective and comparable. The purpose of this study was to compare two different approaches to quantify ankle joint kinematics: Functionally determined joint centres/axes (FA) versus a predictive model (PA). A single comprehensive marker set was defined. Twenty-two subjects were analysed, and distinctive gait variables were averaged across five trials. Agreement between methods was quantified according to Bland & Altman (Bland and Altman 1986. Lancet, i (8476), 307). Outcome variables differed remarkably between FA and PA at the talocrural (2–9°) and subtalar joints (1–6°). Considerable differences between variables describing motion of the ankle joint complex were primarily related to the use of different rotational axes and definitions of foot segments. This should be considered when studies using different foot models are compared.

The aim of this work was to use bone anchored external markers to describe the kinematics of the tibia, fibula, talus, calcaneus, navicular, cuboid, medial cuneiform, first and fifth metatarsals during gait. Data were collected from six subjects. There was motion at all the joints studied. Movement between the talus and the tibia showed the expected predominance of sagittal plane motion, but the talocalcaneal joint displayed greater variability than expected in its motion. Movement at the talonavicular joint was greater than at the talocalcaneal joint and motion between the medial cuneiform and navicular was far greater than expected. Motion between the first metatarsal and the medial cuneiform was less than motion between the fifth metatarsal and cuboid. Overall the data demonstrated the complexity of the foot and the importance of the joints distal to the rearfoot in its overall dynamic function.

The risk of injury during landing after a jump is considered high, because large moments can force the foot into a distortion. The goals of this investigation were to measure the foot-movements during landing and to check the hypothesis, whether with changes at the shoe sole the rearfoot can be brought into a vertical and therefore stable position during the landing movement. The results show, that during landing the foot twists between forefoot and rearfoot. This movement is referred to as torsion and is described in detail in the anatomical literature. With grooves in the shoe sole the torsion with shoes comes closer to the barefoot values. The rearfoot is stabilized by 5-10 degrees and the risk of injury is decreased.

The effect of three different types of support inlays for sports shoes was investigated in the basis of measurements made on 37 athletes who use such shoes in their daily training. The date were obtained from force measurements (repulsion force on the ground) and with the aid of films. The investigation showed that there was no difference in the average values of the three types of support (loose inlay, glued-in inlay and support permanently attached to the shoe). All the supports reduced medial bending at the ankle joint. None of them caused a reduction medial bending at the ankle joint. None of them caused a reduction of repulsion forces when the foot came into contact with the support. In propulsion, all the supports caused an increase in the lateral outturn of the foot. The scatter range in the measurements obtained with the loose inlay was greater; a connection was found between this and the possibility of the foot slipping in the shoe.

Background: The dependence of the movements of the calcaneus, cuboid, navicular, and talus on each other have been described as the tarsal gearbox. To provide a basis of its modeling, data on transmissions between tarsal joint rotations within this gearbox are required. The feasibility of tibiocalcaneal rotations to predict tarsal joint rotations is of interest because a meaningful relation would allow the use of common motion analysis with skin markers to investigate rearfoot kinematics. Methods: We performed linear regression analyses between tarsal joint and tibiocalcaneal rotations on the basis of magnetic resonance imaging of tibia and tarsal bone positions during quasi-static foot pronation and supination. Results: In the frontal plane and transverse planes, linear models were found to predict tarsal joint rotations quite well (r2 = 0.83–0.97 for the frontal plane and r2 = 0.73–0.95 for the transverse plane). For each degree of talocalcaneal rotation, there was 1.8° of talonavicular rotation in the frontal plane and 1.6° in the transverse plane; each degree of talocalcaneal rotation resulted in 0.6° of calcanealcuboid rotation in the frontal plane and 0.7° in the transverse plane; each degree of calcaneocuboid rotation resulted in 3° of talonavicular rotation in the frontal plane and 2.8° in the transverse; each degree of tibiocalcaneal rotation resulted in 0.9° of talocalcaneal rotation in the frontal plane and 0.9° in the transverse plane; and each degree of tibiocalcaneal rotation resulted in 1.6° of talonavicular rotation in the frontal plane and 1.3° in the transverse plane. Conclusion: The present study provides a basis on which the tarsal gearbox in the frontal and the transverse planes under quasi-static conditions can be modeled. Furthermore, it is concluded that tibiocalcaneal rotations are practical for predicting tarsal joint rotations during quasi-static motions. (J Am Podiatr Med Assoc 98(1): 45–50, 2008)

The purpose of this study was to determine the reliability of tarsal bone segmentation based on magnetic resonance (MR) imaging using commercially available software. All tarsal bones of five subjects were segmented five times each by two operators. Volumes and second moments of volume were calculated and used to determine the intra- as well as interoperator reproducibility. The results show that these morphological parameters had excellent interclass correlation coefficients (0.997) indicating that the presented tarsal bone segmentation is a reliable procedure and that operators are in fact interchangeable. The consequences on differences in MR kinematic analysis methods of segmentation due to repetition were also determined. It became evident that one analysis method--fitting surface point clouds--was considerable less affected by repeated segmentation (cuboid: up to 0.2 degrees, other tarsal bones up to 0.1 degrees) compared to a method using principal axes (cuboid up to 6.7 degrees, other tarsal bones up to 0.8 degrees). Thus, the former method is recommended for investigations of tarsal bone kinematics by MR imaging.

The purpose of this study was to quantify kinetic and kinematic effects during the stance phase of walking using three different foot orthoses. All test subjects were measured under five test conditions with 10 repetitions each. The test conditions included: neutral orthosis (tested twice) and three different orthoses (posting, molding and posting combined, proprioceptive). Whereas most previous studies rely on healthy subjects to describe effects of orthoses during gait, the present study used eight patients (all pes valgus). Standard gait analysis was used with force plates (KISTLER) and an optoelectric measuring system (VICON). The results show that the combined molding and posting foot orthosis significantly reduced eversion and eversion moments during walking compared to a posting type and a proprioceptive orthosis in several test parameters. EMG measurements with fine wire electrodes on three of the test subjects revealed that the activity pattern of the tibialis posterior muscle can considerably change between subjects but may not be used to explain apparent individual effects. The results suggest that for subjects with pes valgus a combined molding and posting orthoses reduces eversion best and that individual variations may be due to subject dependent proprioception, internal foot mechanics and/or a combination of both.

Magnetic resonance (MR) imaging is becoming increasingly important in the study of foot biomechanics. Specific devices have been constructed to load and position the foot while the subject is lying supine in the scanner. The present study examines the efficacy of such a newly developed device in replicating tarsal kinematics seen during the more commonly studied standing loading conditions. The results showed that although knee flexion and the externally applied load were carefully controlled, subtalar and talo-navicular joint rotations while lying during MR imaging and when standing (measured opto-electrically with markers attached to intracortical pins) did not match, nor were they systematically shifted. Thus, the proposed MR protocol cannot replicate tarsal kinematics seen during upright standing. It is concluded that specific foot loading conditions have to be considered when tarsal kinematics are evaluated. Improved replication of tarsal kinematics in different postures should comprehensively consider muscle activity, a fixed hip position, and a well-defined point of load application.

The goal of this study was to compare selected parameters of vertical ground reaction forces (GRF) of good outcome patients with different prosthesis designs with a matched control group during level walking, stair ascent and descent. Forty subjects, 29 with three main implant designs (including four subjects with a passive knee flexion restriction), and 11 healthy controls were measured with 8-10 repetitions. Vertical ground reaction forces were measured during two consecutive steps with force plates embedded in the walkway and the staircase. Defined parameters of the force signals were used to compare the results of the test groups. The results show, that, postoperatively, good outcome patients produce gait patterns of the vertical ground reaction force which are comparable to normal healthy subjects with the exception of a few distinct differences: a significant reduction (p

An accurate kinematic description of the intrinsic articulations of the foot during running has not previously been presented, primarily due to methodological limitations. An invasive method based upon reflective marker arrays mounted on intracortical pins drilled into the bones was used in this study. Four male volunteers participated as subjects. Pins (1.6mm diameter) were inserted under local anaesthetic in the tibia, fibula, calcaneus, talus, navicular, cuboid, medial cuneiform and metatarsals I and V. A 10 camera motion analysis system was used for kinematic data capture and the ground reaction force was simultaneously measured. Segment motion relative to adjacent proximal segments was determined using helical axes projected into the coordinate system of the proximal segment. Coefficients of multiple correlation calculated to determine the strength of association between running style with and without the pins inserted indicated that the subjects had little restriction due to the inserted pins. Individual and mean results were presented for rotations defined in the planes of the proximal segment's coordinate system and showed frontal plane rotation of the talocrural joint (12.2+/-7.1 degrees ), which exceeded that of the subtalar joint (8.9+/-3.2 degrees ). Considerable mobility of the talonavicular joint was found (6.5+/-2.9 degrees , 13.5+/-4.1 degrees and 8.7+/-1.4 degrees in the sagittal, frontal and transverse planes, respectively). Furthermore, little, but non-negligible motion between the fibula and tibia was found (3.3+/-2.4 degrees in the sagittal plane). The presented data are of interest as input for future biomechanical modelling and clinical decision making in particular, concerning joint fusion.

Malalignment, in particular femoral component malrotation, is a commonly accepted failure mode in total knee arthroplasty. The general objective of this paper is twofold: firstly, it accentuates clinical observations of the effects of rotational malalignment in total knee arthroplasty. Secondly, it discusses the relevant parameters of existing knee joint models with regards to rotational malalignment and its biomechanical background, thereby setting a basis for future studies. To summarise, when modelling malalignment in total knee arthroplasty, the following aspects should be considered: Friction between the implant components, ligamentous and capsular structures, deformable body to model the PE inlay, and an in vivo validation of the model. Because of the large variance in anthropometrical data between individuals, future knee joint models should also incorporate individual data.

The biomechanics of the human tarsus have been extensively modelled using different types of links within the tarsal bones. Since movement coupling ratios between the calcaneus and tibia have been reported to change continuously, many recent studies accept neither a single rigid hinge joint nor a universal joint representing movement coupling between the rearfoot and lower leg. Traditionally, bony structures and ligaments limiting the range of motion are considered in kinematic chains. However, recent studies suggest distinguishing between limiting (strained) and guiding (isometric) ligaments. The consideration of guiding ligaments in models of tarsal gears has already been shown to improve the simulation of tarsal movements in the sagittal plane. To improve the knowledge on movement coupling, e.g. three-dimensional, additional tarsal gears need to be established. The large discrepancies of the reported movement coupling ratios indicate that there is presently no validation available which allows to characterisation of human tarsal function to an acceptable degree.

The goal of the present article is to provide a review and summary (2) of biomechanical research on the ankle joint, (3) ankle joint models, (4) ankle endoprostheses, and (5) reflections with respect to possible applications of ankle prosthesis design. Knowledge of the biomechanical function is essential for a successful design of a joint replacement for the ankle, which is highly complex. Presently, predictions of joint compressive forces are the primary basis for the design development of artificial total ankle replacements. Shear forces at the bone-to-implant interface, accountable for an increased loosening rate of the implant, are obviated with the so-called unconstrained design philosophy. However, the knowledge of transverse forces and shank torsional moments in conjunction with artificial ankle replacements and problems possibly related to these loads is rare. This review summarizes contributions of relevance with respect to the modelling of the ankle joints and a prosthetic replacement design and discusses some potentially important aspects for future ankle prostheses.

STACOFF, A., C. REINSCHMIDT, B. M. NIGG, A. J. VAN DEN BOGERT, A. LUNDBERG, J. DENOTH, and E. STUSSI. Effectsof shoe sole construction on skeletal motion during running. Med. Sci. Sports Exerc., Vol. 33, No. 2, 2001, pp. 311–319.Purpose: Thepurpose of this study was to quantify effects of shoe sole modification on skeletal kinematics of the calcaneus and tibia during the stancephase of running. Methods: Intracortical bone pins with reflective marker triads were inserted under standard local anesthetic into thecalcaneus and tibia of five healthy male subjects. The three-dimensional tibiocalcaneal rotations were determined using a jointcoordinate system approach. Three shoe sole modifications were tested with different sole geometry: a lateral heel flare of 25° (flared),no flare 0° (straight), and a rounded sole.Results: The results showed that these shoe sole modifications did not change tibiocalcanealrotations substantially. The shoe sole effects at the bone level were small and unsystematic (mean effects being less than 1°) comparedwith the differences between the subjects (up to 7°). Shoe eversion measured simultaneously with shoe markers showed no systematicshoe sole effects. A comparison of shoe and bone results showed the total shoe eversion and maximum shoe eversion velocity to beapproximately twice as large as the respective measurements based on bone markers (correlations being r 5 0.79 for maximum eversionvelocity; r 5 0.88 for total eversion), indicating that there may be a relationship or coupling effect between the shoes and the bone.Conclusions: It is concluded that the tibiocalcaneal kinematics of running may be individually unique and that shoe sole modificationsmay not be able to change them substantially. Key Words: RUNNING INJURIES, SHOES, SOLE FLARE, PRONATION,INTERNAL TIBIAL ROTATION