Irene S. McClay

Arch structure and injury patterns in runners

OBJECTIVE The purpose of this study was to determine if high-arched and low-arched runners exhibit different injury patterns. DESIGN Non-randomized, two-group injury survey. BACKGROUND Running-related injuries are thought to be related, in part, to lower extremity structure. High-arched and low-arched runners with their different bony architecture may exhibit very different lower extremity mechanics and, consequently, different injury patterns. It was hypothesized that high-arched runners will exhibit a greater incidence of lateral injuries, skeletal injuries and knee injuries while low-arched runners will show a greater incidence of medial injuries, soft tissue injuries and foot injuries. METHODS Twenty high-arched and 20 low-arched runners were included in this study. Running-related injuries were recorded and divided into injury patterns of medial/lateral, bony/soft tissue and knee/foot and ankle for both high-arched and low-arched runners. A chi(2) analysis was then employed in an attempt to associate injury patterns with arch structure. RESULTS High-arched runners reported a greater incidence of ankle injuries, bony injuries and lateral injuries. Low-arched runners exhibited more knee injuries, soft tissue injuries and medial injuries. CONCLUSIONS Based on these results, high and low arch structure is associated with different injury patterns in runners. Relevance. Different injury patterns are present in individuals with extreme high arches when compared to those with extremely low arches. These relationships may lead to improved treatment and intervention strategies for runners based on their predisposing foot structure.

Comparison of surface mounted markers and attachment methods in estimating tibial rotations during walking: an in vivo study

The overall goal of this work was to determine an optimal surface-tracking marker set for tracking motion of the tibia during natural cadence walking. Eleven different marker sets were evaluated. The marker sets differed in the location they were attached to the shank, the method used to attach the marker sets to the segment and the physical characteristics of the marker sets. Angular position during stance for each marker set was expressed relative to the orientation of the tibia as measured using bone anchored markers. A marker set consisting of four markers attached to a rigid shell positioned over the distal lateral shank and attached to the leg using an underwrap attachment yielded the best estimate of tibial rotation. Rotational deviations of+/-2 degrees about the medio-lateral and antero-posterior axes, and+/-4 degrees about the longitudinal axis did occur even when using the optimal set of markers.

A comparison of three-dimensional lower extremity kinematics during running between excessive pronators and normals

OBJECTIVE: The purpose of this research was to compare the three-dimensional kinematics of runners exhibiting excessive rearfoot pronation with those having normal rearfoot pronation. DESIGN: The study design was a comparative investigation of two types of running patterns. BACKGROUND: Excessive rearfoot pronation is often linked with overuse injuries of the lower extremity. However, the literature is void of papers describing the rearfoot motion of runners presenting with excessive rearfoot pronation. Many knee-related injuries in runners are associated with increased rearfoot pronation; however, knee mechanics in this population of runners have yet to be studied. Finally, three-dimensional studies are needed to describe joint motion fully during running and these are also lacking. METHODS: Eighteen subjects (nine excessive pronators -- PRs; nine normals -- NLs) were studied during treadmill running at 3.35 m/s. Retroreflective markers were placed on the foot, shank and thigh segments and recorded with four 200 Hz video cameras. Three-dimensional kinematics were computed. RESULTS: A downward shift of the eversion curve was seen in the PR group resulting in an everted position of the rearfoot at both footstrike and toe-off compared with an inverted posture seen in the NL group. The amount of toe-out was not significantly different between the two groups. At the knee, the PR group demonstrated significantly less adduction and significantly greater flexion than the NL. Mean peak velocities of the PR group were greater in all angular measures except knee adduction. However, only foot dorsiflexion and eversion and knee flexion velocities were significantly different. CONCLUSIONS: Kinematic differences were noted at both the rearfoot and the knee of the runners who exhibit excessive rearfoot pronation.

A radiographic analysis of the relationship between the size and shape of the intercondylar notch and anterior cruciate ligament injury

Notch-view radiographs were obtained from 108 persons with anterior cruciate ligament (ACL) injuries (55 women, 53 men) and 186 with intact ACL (94 women, 92 men). Notch width, femur width, and notch width index were determined from each of the 294 radiographs. The notch was also categorized as either A-shaped or non-A-shaped. Intrarater and interrater reliability ranged from 0.82 to 0.99 for notch width and femur width, respectively. Reliability within and between raters for the classification of notch shape ranged from 0.80 to 1.0. Notch width was significantly influenced by a 10° change in knee angle when repeated radiographs were taken. Femur width was not affected by knee angle across this range. Analysis revealed a higher proportion of A-shaped notches among women than men. However, notch shape was not related to injury status. Results showed a smaller notch width and notch width index in ACL-injured patients regardless of notch shape or gender. A-shaped notches were smaller than non-A-shaped notches regardless of injury status or gender. Both notch width and notch width index were found to be significant indicators of ACL injury. Knowledge of the shape of the notch added no useful information in differentiating patients based on injury status. Thus, regardless of gender, individuals who possess smaller notch dimensions appear to be at greater risk of injury than individuals with larger notches.

Three-dimensional kinetic analysis of running: significance of secondary planes of motion.

PURPOSE The study of angular kinetic data provides important information regarding muscle function and may lend insight into the etiology of overuse injuries common to runners. These injuries are often due to deviations in the secondary planes of motion. However, little is known about the angular kinetics in these planes leaving no reference for comparison. METHODS Therefore, three-dimensional kinematic and ground reaction force data were collected on 20 recreational runners with normal rearfoot mechanics. RESULTS Findings suggest that sagittal plane kinetic data were similar to the two-dimensional studies reported in the literature. Sagittal plane data were least variable (CV: 9.3-11.0%) and comprised the largest percentage of positive or negative work done (80.2-88.8%) at both the rearfoot and knee joints. Transverse plane kinetics were most variable (CV: 68.5-151.9%) and constituted the smallest percentage of work done at both joints (0.7-7.4%). CONCLUSIONS Although relatively smaller than the sagittal plane component, a substantial amount of positive work was done in the frontal plane at both joints (16.1-18.9%), suggesting that this component should not be ignored.

Knee moment profiles during walking: errors due to soft tissue movement of the shank and the influence of the reference coordinate system

The effect soft tissue movement of the shank had on knee joint moments during natural cadence walking was investigated in this study. This was examined by comparing knee moments determined from bone-anchored and surface mounted tracking targets. Six healthy adult subjects participated in this study. The largest difference (3 N m) occurred about the AP axis, with smaller differences of approximately 2 and 1 N m about the flexion/extension (F/E) and longitudinal (Long) axes, respectively. The magnitude of these differences would not likely affect the clinical interpretation of the data. The effect of reporting knee moments in two different orthogonal reference systems was also examined. The peak extension moment was significantly greater when expressed about an anatomical axis following the line of the malleoli than when the moment was reported about an axis parallel to the frontal plane of the shank. In contrast, the first peak abduction moment was significantly greater when expressed about an axis perpendicular to the frontal plane of the shank. Care should therefore be exercised whenever comparisons between studies are made in which the reference axes are not aligned.

The Influence of Foot Abduction on Differences between Two-Dimensional and Three-Dimensional Rearfoot Motion

The advantage of a three-dimensional over a two-dimensional approach to rearfoot analysis has been questioned in the past. The purpose of this study was to examine differences in typical rearfoot variables obtained using a two-dimensional analysis compared with a three-dimensional approach. In addition, the influence of foot placement angle on these differences was assessed. Two- and three-dimensional rearfoot kinematics were collected from 18 recreational runners. Two-dimensional values for eversion at toe-off and time to peak eversion were found to be significantly different from the three-dimensional results. Differences between two-dimensional and three-dimensional variables were magnified with increased toe-out. Differences between eversion values were found to be minimal when the foot was abducted between 7 and 10°. The premise that excessive pronators have more pronounced toe-out was not supported by this study. Results suggest that caution should be exercised when assessing two-dimensional rearfoot motion in subjects with excessive toe-out.

Acute effects of the Protonics system on patellofemoral alignment: an MRI study

This study used magnetic resonance imaging (MRI) to determine whether changes in patellofemoral alignment occur after initial treatment with the Protonics exercise device. The first scan was obtained before the device was used. After performing a set of exercises with no resistance on the device the device was removed, and a second scan was obtained. The same set of exercises was again performed with resistance on the device set at the appropriate level, and a final scan was obtained with the device removed. An isometric leg press was maintained as each image was obtained to simulate more closely a functional weight-bearing activity. Subjects were 26 women with complaints of patellofemoral pain. The main outcome measures were: patellar tilt angle, bisect offset, and lateral facet angle. Nonparametric repeated measures analysis of variance tests showed no differences between test conditions for any of the three measures of patellofemoral alignment. We conclude that after an initial treatment session using the Protonics system there is no change in patellofemoral alignment as determined by MRI.

The Subtalar Angle: A Proposed Measure of Rearfoot Structure

The purpose of this study was to propose a new measure of rearfoot structure to further enhance the understanding of the function of the foot. Landmarks visible on sagittal plane radiographs were used to represent the approximate direction of the subtalar joint axis in the sagittal plane based upon descriptions from the literature of its orientation. Four landmarks were chosen, resulting in four calculated angles. One hundred lateral view radiographs were analyzed. The mean values ranged from 28.7° to 47.7°. These values are within the ranges reported from both cadaver and in vivo studies. Tests of repeatability of the measures resulted in intraclass coefficient values between 0.94 and 0.98, suggesting good reliability. All four angles correlated highly among each other (r = 0.88–0.97). Examination of the validity of any one of these measures is left to those who are able to accurately calculate the orientation of the subtalar joint axis.