Christoph Reinschmidt

Effect of skin movement on the analysis of skeletal knee joint motion during running

It is not known how well skin markers represent the skeletal knee joint motion during running. Hence the purpose of this investigation was to compare the skin marker derived tibiofemoral motion with the skeletal tibiofemoral motion during running. In addition to skin markers attached to the shank and thigh, triads of reflective markers were attached to bone pins inserted into the tibia and femur. Three-dimensional kinematics of the stance phase of five running trials were recorded for three subjects using high-speed cine cameras (200 Hz). The knee motion was expressed in terms of Cardan angles calculated from both the external and skeletal markers. Good agreement was present between the skin and bone marker based knee flexion/extension. For abduction/adduction and internal/external knee rotation, the difference between skeletal and external motion was large compared to the amplitude of these motions. Average errors relative to the range of motion during running stance were 21% for flexion/extension, 63% for internal/external rotation, and 70% for abduction/adduction. The errors were highly subject dependent preventing the realization of a successful correction algorithm. It was concluded that knee rotations other than flexion/extension may be affected with substantial errors when using skin markers.

Effects of Foot Orthoses on Skeletal Motion During Running

OBJECTIVE To quantify the effects of medial foot orthoses on skeletal movements of the calcaneus and tibia during the stance phase in running. DESIGN Kinematic effects of medial foot orthoses (anterior, posterior, no support) were tested using skeletal (and shoe) markers at the calcaneus and tibia. BACKGROUND Previous studies using shoe and skin markers concluded that medially placed orthoses control/reduce foot eversion and tibial rotation. However, it is currently unknown if such orthoses also affect skeletal motion at the lower extremities. METHODS Intracortical Hofman pins with reflective marker triads were inserted under standard local anesthetic into the calcaneus and tibia of five healthy male subjects. The three-dimensional tibiocalcaneal rotations were determined using a joint coordinate system approach. Eversion (skeletal and shoe) and tibial rotation were calculated to study the foot orthoses effects. RESULTS Orthotic effects on eversion and tibial rotations were found to be small and unsystematic over all subjects. Differences between the subjects were significantly larger (p<0.01; up to 10 degrees ) than between the orthotic conditions (1-4 degrees ). Significant orthotic effects across subjects were found only for total internal tibial rotation; p<0.05). CONCLUSIONS This in vivo study showed that medially placed foot orthoses did not change tibiocalcaneal movement patterns substantially during the stance phase of running. RELEVANCE Orthoses may have only small kinematic effects on the calcaneus and tibia (measured with bone pins) as well as on the shoes (measured with shoe markers) during running of normal subjects. Present results showed that orthotic effects were subject specific and unsystematic across conditions. It is speculated that orthotic effects during the stance phase of running may be mechanical as well as proprioceptive.

Tibiofemoral and tibiocalcaneal motion during walking: external vs. skeletal markers

Abstract The purpose of this study was to determine the errors in knee (tibiofemoral) and ankle joint complex (AJC; tibiocalcaneal) rotations caused by the skin movement artefact. Intracortical bone pins were inserted into the femur, tibia, and calcaneus of five subjects. Marker triads were attached to these pins, and additionally, six skin markers to the thigh, six to the shank, and three to the shoe. For each subject three walking trials were filmed with three synchronized LOCAM cameras (50 Hz). Flexion/extension, ab/adduction, and longitudinal rotation at the tibiofemoral joint as well as plantar-/dorsiflexion, ab/adduction, and in/eversion at the AJC were calculated from both skin and bone markers during the stance phase of walking. The results showed that the errors in knee rotations were mainly caused by the thigh markers. Knee flexion/extension was generally well reflected with the use of skin markers (mean difference: 2.1°). The agreement between skin and bone marker based kinematics for ab/adduction and internal/external knee rotation ranged from good to virtually no agreement, and in some subjects, the errors exceeded the actual motion. The errors in AJC rotations were mainly caused by the markers on the shoe/foot segment. The tibiocalcaneal rotations were generally well reflected with external markers. However, tibiocalcaneal rotations derived from external markers typically exceeded the true bone motions. The results suggest that (a) knee rotations other than flexion/extension may be affected with substantial errors when using external markers, and (b) tibiocalcaneal rotations are generally well reflected with external markers, but amplitudes are overestimated.

Tibiocalcaneal motion during running, measured with external and bone markers.

OBJECTIVE: The purpose of this study was to compare tibiocalcaneal motion during running based on skeletal markers with tibiocalcaneal motion based on external markers. DESIGN. IN VIVO: measurements of external and skeletal tibiocalcaneal kinematics. BACKGROUND: External (shoe, skin) markers are typically used to determine rearfoot kinematics. However, it is not known if such markers are able to provide a good representation of the skeletal (tibiocalcaneal) kinematics. METHODS: Bone pins were inserted into the tibia and calcaneus of five subjects. The 3-D motion of markers attached to bone pins as well as of external markers attached to the shank and shoe were determined during the stance phase of five running trials. Intersegmental motion was expressed in terms of Cardan angles (plantarflexion/dorsiflexion, abduction/adduction, inversion/eversion). RESULTS: It was found that the skeletal inversion/eversion, abduction/adduction, and plantarflexion/dorsiflexion motions were similar across the subjects. The shape of the tibiocalcaneal rotation curves based on external markers were similar to those based on bone markers. However, the rotations were generally overestimated when using external markers, e.g. the average maximal eversion motion calculated from external markers was 16.0 degrees whereas the skeletal maximal eversion motion was only 8.6 degrees. These discrepancies were mainly due to the relative movement between shoe markers and underlying calcaneus. CONCLUSIONS: External markers are only gross indicators of the skeletal tibiocalcaneal motion. The rotations derived from external shoe and shank markers typically overestimate the skeletal tibiocalcaneal kinematics. RELEVANCE: Quantitative results determined from external markers have to be used with caution. For tibiocalcaneal rotations, external markers may be used to show trends, but absolute values cannot be trusted.

Tibiocalcaneal kinematics of barefoot versus shod running

Barefoot running kinematics has been described to vary considerably from shod running. However, previous investigations were typically based on externally mounted shoe and/or skin markers, which have been shown to overestimate skeletal movements. Thus, the purpose of this study was to compare calcaneal and tibial movements of barefoot versus shod running using skeletal markers. Intracortical bone pins with reflective marker triads were inserted under standard local anesthetic into the calcaneus and tibia of five healthy male subjects. The subjects ran barefoot, with a normal shoe, with three shoe soles and two orthotic modifications. The three-dimensional tibiocalcaneal rotations were determined using a joint coordinate system approach. Test variables were defined for eversion and tibial rotation. The results showed that the differences in bone movements between barefoot and shod running were small and unsystematic (mean effects being less than 2 degrees ) compared with the differences between the subjects (up to 10 degrees ). However, differences may occur during midstance when extreme shoe modifications (i.e. posterior orthosis) are used. It is concluded that calcaneal and tibial movement patterns do not differ substantially between barefoot and shod running, and that the effects of these interventions are subject specific. The result of this in vivo study contrasts with previous investigations using skin and shoe mounted markers and suggests that these discrepancies may be the result of the overestimation with externally mounted markers.

Lateral stability in sideward cutting movements

Sideward cutting movements occur frequently in sports activities, such as basketball, soccer, and tennis. These activities show a high incidence of injuries to the lateral aspect of the ankle. Consequently, the lateral stability of sport shoes seems important. The purpose of this study was to show the effect of different shoe sole properties (hardness, thickness, torsional stiffness) and designs on the lateral stability during sideward cutting movements. A film analysis was conducted including 12 subjects performing a cutting movement barefoot and with five different pairs of shoes each filmed in the frontal plane. A standard film analysis was conducted; for the statistical analysis, various parameters such as the range of motion in inversion and the angular velocity of the rearfoot were used. The results showed a large difference between the barefoot and shod conditions with respect to the lateral stability. Two shoes performed significantly better (P < 0.05) than the others with a decreased inversion movement and less slipping inside the shoe. The two shoes differed mainly in the shoe sole design (hollow inner core) and the upper (high-cut). It is concluded that lateral stability may be improved by altering the properties and design of the shoe sole as well as the upper.

Effects of shoe sole construction on skeletal motion during running

PURPOSE The purpose of this study was to quantify effects of shoe sole modification on skeletal kinematics of the calcaneus and tibia during the stance phase of running. METHODS Intracortical bone pins with reflective marker triads were inserted under standard local anesthetic into the calcaneus and tibia of five healthy male subjects. The three-dimensional tibiocalcaneal rotations were determined using a joint coordinate system approach. Three shoe sole modifications were tested with different sole geometry: a lateral heel flare of 25 degrees (flared), no flare 0 degrees (straight), and a rounded sole. RESULTS The results showed that these shoe sole modifications did not change tibiocalcaneal rotations substantially. The shoe sole effects at the bone level were small and unsystematic (mean effects being less than 1 degrees ) compared with the differences between the subjects (up to 7 degrees ). Shoe eversion measured simultaneously with shoe markers showed no systematic shoe sole effects. A comparison of shoe and bone results showed the total shoe eversion and maximum shoe eversion velocity to be approximately twice as large as the respective measurements based on bone markers (correlations being r = 0.79 for maximum eversion velocity; r = 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 modifications may not be able to change them substantially.

The movement of the heel within a running shoe.

Most running shoe investigations have used the same standard procedure for the evaluation of the shoes: the runners are filmed from behind and a film analysis is carried out digitizing markers at the heel counter of the shoe and on the lower leg. The angular displacement of these markers relative to the horizontal or the vertical is assumed to be an indicator for various sports injuries. The goal of this investigation was to measure the movement of the heel counter as well as the movement of the heel inside the shoe. First, the influence of the size of different heel counter windows was controlled and found negligible for the test conditions of this study. Second, 15 subjects performed the following procedure: running (a) barefoot, (b) with shoes with windows, and (c) without windows. Overall, the heel was found to move similarly but not identically to the heel counter. The maximum change of pronation was (a) 13.7 +/- 3.7 degrees, barefoot; (b) 14.1 +/- 3.8 degrees for the shoe with windows and 12.1 +/- 3.7 degrees for the heel inside these shoes; and 14.9 +/- 4.2 degrees for the shoes with no windows. To achieve a general impression of a shoe in the sense of a qualitative description, the previous method without heel counter windows still seems adequate. However, for a detailed analysis of quantitative nature, it is important to use the method with heel counter windows.

Helical axes of skeletal knee joint motion during running.

The purpose of this study was to determine the changes in the axis of rotation of the knee that occur during the stance phase of running. Using intracortical pins, the three-dimensional skeletal kinematics of three subjects were measured during the stance phase of five running trials. The stance phase was divided into equal motion increments for which the position and orientation of the finite helical axes (FHA) were calculated relative to a tibial reference frame. Results were consistent within and between subjects. At the beginning of stance, the FHA was located at the midepicondylar point and during the flexion phase moved 20mm posteriorly and 10mm distally. At the time of peak flexion, the FHA shifted rapidly by about 10-20mm in proximal and posterior direction. The angle between the FHA and the tibial transverse plane increased gradually during flexion, to about 15 degrees of medial inclination, and then returned to zero at the start of the extension phase. These changes in position and orientation of FHA in the knee should be considered in analyses of muscle function during human movement, which require moment arms to be defined relative to a functional rotation axis. The finding that substantial changes in axis of rotation occurred independent of flexion angle suggests that musculoskeletal models must have more than one kinematic degree-of-freedom at the knee. The same applies to the design of knee prostheses, if the goal is to restore normal muscle function.

Movement coupling at the ankle during the stance phase of running.

The purpose of this study was to quantify movement coupling at the ankle during the stance phase of running using bone-mounted markers. Intracortical bone pins with reflective marker triads were inserted under standard local anaesthesia into the calcaneus and the tibia of five healthy male subjects. The three-dimensional rotations were determined using a joint coordinate system approach. Movement coupling was observed in all test subjects and occurred in phases with considerable individual differences. Between the shoe and the calcaneus coupling increased after midstance which suggested that the test shoes provided more coupling for inversion than for eversion. Movement coupling between calcaneus and tibia was higher in the first phase (from heel strike to midstance) compared with the second phase (from midstance to take-off). This finding is in contrast to previous in-vitro studies but may be explained by the higher vertical loads of the present in-vivo study. Thus, movement coupling measured at the bone level changed throughout the stance phase of running and was found to be far more complex than a simple mitered joint or universal joint model.