A comparison of semi-custom and custom foot orthotic devices in high- and low-arched individuals during walking

BACKGROUND

Orthotic devices can be a successful treatment for lower extremity injuries. However, the high cost of custom devices prevents some patients from purchasing them. Some orthotic companies have begun to offer a less expensive, semi-custom alternative. The purpose of this study was to examine whether the semi-custom devices can provide similar rearfoot control and comfort as custom devices in individuals with excessively high- and low-arches.

METHODS

Thirty-seven subjects walked through the motion analysis lab under three conditions: no-orthotic, custom orthotics, and semi-custom orthotics. Rearfoot kinematics and comfort were collected in each device.

FINDINGS

Both devices were effective at reducing eversion velocity and excursion. As compared to the no-orthotic condition, the custom device significantly decreased eversion velocity (P=0.03), while the semi-custom device showed a trend toward decreased eversion velocity (P=0.09). Eversion excursion was significantly reduced in both orthotic conditions (P<0.01). In terms of comfort, high-arched individuals tended to be more comfortable in the semi-custom device in the heel and arch regions. However, the differences in comfort between the devices were generally small (<7%).

INTERPRETATION

Overall, with respect to a comfort and ability to control rearfoot motion, the semi-custom orthotic device is a feasible alternative to the custom orthotic device for high- and low-arched individuals.

A prospective study of iliotibial band strain in runners

BACKGROUND

Iliotibial band syndrome is the leading cause of lateral knee pain in runners. It is thought that pain develops from strain on the iliotibial band due to friction of the iliotibial band sliding over the lateral femoral epicondyle. The purpose of this study was to investigate mechanical strain in the iliotibial band as a possible causative factor in the development of iliotibial band syndrome.

METHODS

From a large prospective study, female runners who incurred iliotibial band syndrome during the study were compared to a control group who incurred no injuries. Strain, strain rate and duration of impingement were determined from a musculoskeletal model of the lower extremity.

FINDINGS

The results indicated that the iliotibial band syndrome subjects exhibited greater strain throughout the support period, but particularly at midsupport compared to the control group. Strain rate was significantly greater in the iliotibial band syndrome group compared to the control group and was greater in the involved limb of the iliotibial band syndrome group compared to their contralateral limb. However, there were no differences in the duration of impingement between the groups.

INTERPRETATION

This study indicates that a major factor in the development of iliotibial band syndrome is strain rate. Therefore, we suggest that strain rate, rather than the magnitude of strain, may be a causative factor in developing iliotibial band syndrome. The effect size (>0.5) indicated that strain rate may be biologically significant in the etiology of iliotibial band syndrome.

A common variant in the 3'UTR of the GRIK4 glutamate receptor gene affects transcript abundance and protects against bipolar disorder

Underactivity of the glutamatergic system is an attractive model for the pathophysiology of several major mental illnesses. We previously described a chromosome abnormality disrupting the kainate class ionotropic glutamate receptor gene, GRIK4/KA1, in an individual with schizophrenia and learning disability (mental retardation). We also demonstrated in a case-control study that two physically separated haplotypes within this gene were significantly associated with increased risk of schizophrenia and decreased risk of bipolar disorder, respectively. The latter protective haplotype was located at the 3' end of the gene. We now report the identification from carriers of the protective haplotype of a deletion variant within the 3' untranslated region of the gene. The deletion allele also was found to be negatively associated with bipolar disorder in both initial (P = 0.00000019) and replication (P = 0.0107) case-control studies. Expression studies indicated that deletion-carrying mRNA transcripts were relatively more abundant. We postulate that this may be a direct consequence of the differences in the RNA secondary structures predicted for the insertion and deletion alleles. These data suggest a mechanism whereby the genetic protective effect is mediated through increased kainate receptor expression.

The symmetry angle: a novel, robust method of quantifying asymmetry

Quantification of asymmetry is a common objective in both research and clinical settings. The most common method for quantification of asymmetry of discrete variables is calculation of the symmetry index. Essentially a measure of the percent difference between sides, the symmetry index requires the choice of a reference value. This is a limitation as the choice of value is not always clear, and can lead to inconsistent results and artificially inflated values. Therefore, the purposes of the current study were to examine the limitations of the symmetry index in depth, define a new method of quantifying symmetry that is robust to those limitations (the symmetry angle), and compute the correlations between the two measures. The results showed that, when using the symmetry index, the interpretation of asymmetry can be highly affected by the choice of reference value. The symmetry angle does not require the choice of a reference value. Therefore, it is not prone to the same limitations. While symmetry angle values tend to be smaller than symmetry index values, the measures are very highly correlated. This suggests that the symmetry angle is a good substitute for the symmetry index. Future studies of asymmetry may benefit from the use of the symmetry angle, as it is equally effective for identifying intra-limb differences as the symmetry index, but is not prone to problems due to normalization and provides a standard scale (+/-100%) to interpret results.

Non-consecutive versus consecutive footstrikes as an equivalent method of assessing gait asymmetry

Asymmetry of gait is often studied to characterize populations and assess the efficacy of treatment protocols. However, despite the continuous nature of gait, many studies have made comparisons between data from non-consecutive footstrikes. This is typically considered a limitation of these studies. However, if gait characteristics are sufficiently repeatable within a side, consecutive footstrikes may not be necessary to properly describe the asymmetry between sides. Therefore, one purpose of this study was to compare asymmetry values calculated from consecutive and non-consecutive footstrikes. Additionally, the variability of gait within and between sides was compared to assess the repeatability and distinctiveness of the characteristics on each side. The results suggest that kinetic and kinematic asymmetry can be assessed from either consecutive or non-consecutive footstrikes. Further, the patterns of movement tend to be sufficiently consistent within a side, such that the variability within a side is much lower than the variability between sides. However, there may be some variables, or populations, that exhibit high within-side variability. Several trials of consecutive footstrikes may be a better way to characterize asymmetry of those variables.

ASB clinical biomechanics award winner 2006 prospective study of the biomechanical factors associated with iliotibial band syndrome

BACKGROUND

Iliotibial band syndrome is the leading cause of lateral knee pain in runners. Despite its high prevalence, little is known about the biomechanics that lead to this syndrome. The purpose of this study was to prospectively compare lower extremity kinematics and kinetics between a group of female runners who develop iliotibial band syndrome compared to healthy controls. It was hypothesized that runners who develop iliotibial band syndrome will exhibit greater peak hip adduction, knee internal rotation, rearfoot eversion and no difference in knee flexion at heel strike. Additionally, the iliotibial band syndrome group were expected to have greater hip abduction, knee external rotation, and rearfoot inversion moments.

METHODS

A group of healthy female recreational runners underwent an instrumented gait analysis and were then followed for two years. Eighteen runners developed iliotibial band syndrome. Their initial running mechanics were compared to a group of age and mileage matched controls with no history of knee or hip pain. Comparisons of peak hip, knee, rearfoot angles and moments were made during the stance phase of running. Variables of interest were averaged over the five running trials, and then averaged across groups.

FINDINGS

The iliotibial band syndrome group exhibited significantly greater hip adduction and knee internal rotation. However, rearfoot eversion and knee flexion were similar between groups. There were no differences in moments between groups.

INTERPRETATION

The development of iliotibial band syndrome appears to be related to increased peak hip adduction and knee internal rotation. These combined motions may increase iliotibial band strain causing it to compress against the lateral femoral condyle. These data suggest that treatment interventions should focus on controlling these secondary plane movements through strengthening, stretching and neuromuscular re-education.

Use of an interferon-gamma based assay to assess bladder cancer patients treated with intravesical BCG and exposed to tuberculosis

OBJECTIVE

Compare the QuantiFERON-TB Gold In-Tube (QFT) assay and the tuberculin skin test (TST) in bladder cancer patients receiving high dose BCG therapy (BCG patients).

DESIGN AND METHODS

BCG patients and healthy visitors, both exposed to tuberculosis, were screened with a TST and QFT.

RESULTS

QFT-TST correlation was excellent in visitors, but poor in BCG patients. BCG therapy predicted a positive TST (p<0.001) but not a positive QFT (p=0.35).

DISCUSSION

The management of BCG patients was impacted, by measuring the QFT.

Effect of footwear on high and low arched runners' mechanics during a prolonged run

INTRODUCTION

Running shoes are designed specifically for different foot types in order to reduce injuries. Running in the correct footwear matched for foot type may have a greater influence on mechanics when runners become exerted. Therefore, the purpose of this study was to evaluate changes in kinematics and kinetics over the course of a prolonged run when low (LA) and high (HA) arched runners wear motion control and cushioning shoes.

METHODS

Twelve HA and 12 LA recreational runners were recruited for this study. Subjects ran in a motion control (MC) and cushion trainer (CT) shoe. Lower extremity kinematics and tibial accelerometry were collected while the runners ran at a self-selected training pace. The data were analyzed using a two-way (footwear x time) repeated measures ANOVA (p=0.05) for each arch type.

RESULTS

Low arched runners: Peak tibial internal rotation decreased in the MC shoe and was increased in the CT over the course of the prolonged run. However, no interactions or main effects were noted for peak eversion or eversion excursion. High arched runners: No shoe by time interaction was observed for tibial shock. However, there was a main effect for shoe, with lower tibial shock associated with the CT shoe.

CONCLUSION

In LA runners, MC shoes decreased tibial internal rotation compared to CT shoes over the course of a prolonged run. In HA runners, running in the CT shoes reduced tibial shock compared to the MC shoes.

Discrete and continuous joint coupling relationships in uninjured recreational runners

BACKGROUND

Abnormal joint coupling is thought to be related to overuse injuries in runners. However, researchers do not yet know what constitutes normal joint coupling during running, which makes abnormal coupling difficult to define.

METHODS

Lower extremity kinematics were collected from 40 recreational runners during stance. Joint coupling methods were applied and, for each method, means and both within- and between-subject variability were calculated. The 95% confidence interval was used to compare differences across coupling relationships and periods of stance.

FINDINGS

Timing between rearfoot eversion, tibial internal rotation, and knee flexion were relatively synchronous while relationships involving knee internal rotation were more asynchronous. The excursion ratios showed that every 2 degrees of rearfoot eversion was coupled with 1 degrees of both tibial internal rotation and knee internal rotation. Vector coding results showed that just beyond maximum loading, all joint coupling relationships resulted in relatively equal amounts of motion, while the within-subject variability was similar throughout stance. The continuous relative phase results showed that the most out-of-phase coupling occurred in the periods around heel-strike and toe-off while the most in-phase coupling occurred in the period just beyond maximum loading of the leg. The continuous relative phase within-subject variability was greatest at the periods around heel-strike and toe-off and smallest just beyond maximum loading.

INTERPRETATION

With a better understanding of joint coupling in uninjured runners, these data will help to serve as a reference for future studies investigating the relationship between running injuries and abnormal joint coupling.

The effect of a single treatment of the Protonics system on lower extremity kinematics during gait and the lateral step up exercise

INTRODUCTION

Patellofemoral pain (PFP) is often attributed to abnormal patellar tracking. The Protonics knee orthosis was developed to reduce femoral internal rotation by altering pelvic alignment via hamstring activation. The purpose of this research was to determine if a single treatment with the orthosis improved lower extremity alignment during gait and the lateral step up exercise. We hypothesized that anterior pelvic tilt, hip internal rotation and adduction, and external rotation of the tibia with respect to the femur would decrease after use of the brace.

METHODS

Nineteen females (23.4+/-3.1 year, 1.66+/-0.05 m, 65.3+/-20.4 kg) with chronic PFP participated. Three-dimensional kinematic data were collected for each subject at 60 Hz during pre-treatment (PRE), after a placebo condition with the orthosis set at zero resistance (PLAC), and post-treatment (POST). Treatment consisted of having the subject perform the rehabilitation exercises recommended by the Protonics manufacturer. A repeated measures ANOVA was performed on each dependent variable (alpha=0.05).

RESULTS

This investigation did not verify the changes in alignment proposed by the manufacturer as a result of acute application of the Protonics system. However, after the use of the brace, pelvic rotation and hip hike were decreased during the lateral step up exercise.

CONCLUSION

Based on the results of this study, it was concluded that a single application of the Protonics system did not alter anterior pelvic tilt, hip internal rotation and adduction, or tibial external rotation during the lateral step up and gait.

Core strength and lower extremity alignment during single leg squats

INTRODUCTION/PURPOSE

Muscles of the trunk, hip, and knee influence the orientation of the lower extremity during weight bearing activities. The purpose of this study was threefold: first, to compare the orientation of the lower extremity during a single leg (SL) squat among male and female athletes; second, to compare the strength of muscle groups in the trunk, hips, and knees between these individuals; and third, to evaluate the association between trunk, hip, and knee strength and the orientation of the knee joint during this activity.

METHODS

Twenty-four male and 22 female athletes participated in this study. Peak isometric torque was determined for the following muscle actions: trunk flexion, extension, and lateral flexion, hip abduction and external rotation, and knee flexion and extension. The frontal plane projection angle (FPPA) of the knee during a 45 degrees SL squat was determined using photo editing software.

RESULTS

Males and females moved in opposite directions during the SL squat test (F(1,42) = 5.05, P = 0.03). Females typically moved toward more extreme FPPA during SL squats (P = 0.056), while males tended to move toward more neutral alignment (P = 0.066). Females also generated less torque in all muscle groups, with the exception of trunk extension. The projection angle of the knee during the SL squat test was most closely associated with hip external rotation strength.

CONCLUSION

Using instruments suitable for a clinical setting, females were found to have greater FPPA and generally decreased trunk, hip, and knee isometric torque. Hip external rotation strength was most closely associated with the frontal plane projection angle.