Cartilage transverse relaxation time (T2) has been reported to be sensitive to OA-related changes in cartilage composition, but no study previously reported reference values for femorotibial (FTJ) ...cartilage T2 side-to-side differences for persons with or without previous ACL injury. Since articular cartilage extracellular matrix has a layered organization, this study focused on laminar (deep and superficial) T2 cartilage times.
To assess 1) whether laminar cartilage T2 obtained in two different age groups differs between ACL-injured and contralateral knees and 2) whether between-knee differences differ between ACL injured and healthy controls of the two age groups. In addition, we report laminar T2 thresholds for between-knee differences of healthy controls.
85 participants in four groups (20–30 years healthy, HEA20–30, n=24; 20–30 years ACL injured, ACL20–30, n=23; 40–60 years healthy, HEA40–60, n=24; 40–60 years ACL injured, ACL40–60, n=14) completed data collection. ACL injured participants had a unilateral ACL injury 2–10 years before inclusion. MRIs of HEA left (HEA_l) and right (HEA_r) or ACL injured (ACL_in) and uninjured (ACL_unin) side were acquired using a quantitative 3D DESS sequence (in plane resolution 0.3125*0.3125mm, slice thickness 1.5mm, resolution 512*512, TR 17 ms, TE1 4.85ms, TE2 9.75 ms, FA 15°). Weight-bearing FTJ cartilage plates were manually segmented by Chondrometrics into deep 50% (.D) and superficial 50% (.S) zones and total (.T) cartilage. Between-knee differences in T2 for the FTJ (dif_FTJ) were computed from T2 means (HEA_l–HEA_r or ACL_in–ACL_unin). Nonparametric Dunn and Conover-Iman tests were used for between-group and between-knee comparisons, respectively. Holm correction was used to adjust for multiple comparisons (P<0.05). 80% thresholds for detecting differences between knees were computed from healthy participants as mean(dif_FTJ HEA20–30) ± 1.28*SD(dif_FTJ HEA20–30), and the numbers of participants showing differences in each group exceeding these thresholds were obtained.
Deep zone T2 was longer in ACL_in than in ACL_unin and HEA knees (Fig. A). Between-knee differences were only bigger in ACL20–30 and ACL40–60 than in HEA20–30 or HEA40–60 for deep zone dif_FTJ (Fig. B) and not for superficial dif_FTJ (Fig. C) or total dif_FTJ (Fig. D). For deep zone dif_FTJ, the number of participants outside the 80% threshold limits of -1.57 to 1.60 ms was 3/24 (12.5 %) for HEA20–30, 15/23 for (65.2 %) for ACL20–30, 5/24 (20.8 %) for HEA40–60 and 11/14 (78.6 %) for ACL40–60.
Elevated FTJ deep zone T2 2 to 10 years after ACL injury (with or without surgical ACL reconstruction) suggests a reduction in cartilage quality (i.e. alterations in cartilage composition and mechanics) after trauma. Comparable deep zone dif_FTJ after ACL injury for both age groups suggests that trauma affects cartilage quality in both groups equally. We conclude that the effects of ACL injury were most pronounced in deep zone T2 and most ACL injured participants showed between-knee differences outside the threshold limits for healthy articular cartilage.
Objective. To quantify the effects of posting and custom-molding of foot orthotics on lower extremity kinematics and kinetics during running.
Design. Repeated measures.
Background. Several kinematic ...and kinetic factors have been suggested to increase a runner’s risk for injuries. It has been speculated that foot orthotics can be used to reduce injury related complaints or even prevent running injuries by affecting these factors.
Methods. Twenty one volunteers participated in this study. Kinematic and kinetic variables obtained during overground running for medial posting, custom-molding, and the combination of medial posting and custom-molding of foot orthotics were compared to a control condition. Repeated measures
anova and student
t-tests were used to detect significant differences (
α=0.05).
Results. Posting of foot orthotics reduced maximum foot eversion and ankle inversion moment and increased vertical loading rate and maximum knee external rotation moment (
P<0.05). Molding and posting and molding reduced vertical loading rate and ankle inversion moment and increased maximum foot inversion and maximum knee external rotation moment (
P<0.05).
Conclusions. The effects of posting and molding of foot orthotics are extremely different and when combining posting and molding, the effects of molding appear to be dominant. It yet remains to be determined whether posting or molding is more beneficial with respect to overuse running injuries.
Relevance The potential of foot orthotics for reducing pain and injuries is convincing. The current study provides valuable information about the role of specific structural components of foot orthotics and contributes to the knowledge about the mechanism underlying the effect of foot orthotics in running.
The purpose of this study was to quantify the effects of selected foot orthoses on muscle activity in the lower extremity during running. Nine male and 12 female recreational runners, clinically and ...functionally classified as ‘pronators’, volunteered for this study and performed over-ground running trials at 4
m/s in each of four experimental conditions: control, posting, molding, and posting & molding. Electromyographic (EMG) signals were recorded from seven lower extremity muscles. Wavelet analysis was performed to obtain EMG intensities in two frequency bands that were averaged for the pre-heel-strike and post-heel-strike intervals and for 30–100% of stance phase. Posting and custom-molding of foot orthoses increased the global EMG intensity of most muscles of the lower extremity for the stance phase of running (
P
<
0.05). The increases in EMG intensity were greater in the high- than in the low-frequency bands for some lower extremity muscles (
P
<
0.05). The effects on muscle activity of posting and custom-molding of foot orthoses differed between the three phases of running gait. The three tested foot orthoses did affect lower extremity muscle activity differently and these effects were specific to the phases of running gait. Combinations of increased requirements of controlling joint motion and minimizing soft tissue vibrations may have led to greater increases in shank muscle activity for the posted condition. The substantial changes in EMG due to orthotic interventions found in this study documents the importance of the study of muscle activity as a reaction to shoe inserts and foot orthoses.
The purposes of this project were to assess the effect of four different shoe inserts on the path of the center of pressure (COP), to quantify the effect of these inserts on selected knee joint ...moments during running, and to assess the potential of COP data to predict the effects of inserts/orthotics on knee joint moments.
Kinematics for the lower extremities, resultant ankle and knee joint moments, and the path of the COP were collected from the right foot of 15 male subjects while running heel-toe with five different shoe inserts (full or half with 4.5-mm postings).
Individual movement changes with respect to the neutral insert condition were typically small and not systematic. Significant changes for the path of the COP were registered only for the full lateral insert condition with an average shift toward the lateral side. The mediolateral shift of the COP was not consistent for the full medial and the two half-shoe inserts. The subject-specific reactions to the inserts' intervention in the corresponding knee joint moments were typically not consistent. Compared with the neutral insert condition, subjects showed increases or decreases of the knee joint moments. The correlation between the individual COP shifts and the resultant knee joint moment was generally small.
The results of this study showed that subject-specific reactions to the tested inserts were often not as expected. Additionally, reactions were not consistent between the subjects. This result suggests that the prescription of inserts and/or orthotics is a difficult task and that methods must be developed to test and assess these effects. Such methods, however, are not currently available.
The purpose of this study was to determine the relationship between differences in comfort and changes in lower extremity kinematic and kinetic variables and muscle activity in response to foot ...orthoses.
Twenty-one recreational runners volunteered for this study. Three orthotic conditions (posting, custom-molding, and posting and custom-molding) were compared with a control (flat) insert. Lower extremity kinematic, kinetic, and EMG data were collected for 108 trials per subject and condition in nine sessions per subject for overground running at 4 m.s-1. Comfort for all orthotic conditions was assessed in each session using a visual analog scale. The statistical tests used included repeated measures ANOVA, linear regression analysis, and discriminant analysis (alpha = 0.05).
Comfort ratings were significantly different between orthotic conditions and the control condition (lower, upper confidence limits; posting: -3.1, -0.8; molding: 0.4, 3.4; and posting and molding: -1.1, 1.9); 34.9% of differences in comfort were explained by changes in 15 kinematic, kinetic, and EMG variables. The 15 kinematic, kinetic, and EMG variables that partially explained differences in comfort classified 75.0% of cases correctly to the corresponding orthotic condition.
In general, comfort is an important and relevant feature of foot orthoses. Evaluations of foot orthoses using comfort do not only reflect subjective perceptions but also differences in functional biomechanical variables. Future research should focus on defining the relationship between comfort and biomechanical variables for material modifications of footwear, different modes of locomotion, and the general population.
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