Faculty Bibliography

PURPOSE: The present review highlights current concepts regarding the effects of diabetic peripheral neuropathy (DPN) in skeletal muscle. It discusses the lack of effective pharmacologic treatments and the role of physical exercise intervention in limb protection and symptom reversal. It also highlights the importance of magnetic resonance imaging (MRI) techniques in providing a mechanistic understanding of the disease and helping develop targeted treatments. METHODS: This review provides a comprehensive reporting on the effects of DPN in the skeletal muscle of patients with diabetes. It also provides an update on the most recent trials of exercise intervention targeting DPN pathology. Lastly, we report on emerging MRI techniques that have shown promise in providing a mechanistic understanding of DPN and can help improve the design and implementation of clinical trials in the future. FINDINGS: Impairments in lower limb muscles reduce functional capacity and contribute to altered gait, increased fall risk, and impaired balance in patients with DPN. This finding is an important concern for patients with DPN because their falls are likely to be injurious and lead to bone fractures, poorly healing wounds, and chronic infections that may require amputation. Preliminary studies have shown that moderate-intensity exercise programs are well tolerated by patients with DPN. They can improve their cardiorespiratory function and partially reverse some of the symptoms of DPN. MRI has the potential to bring new mechanistic insights into the effects of DPN as well as to objectively measure small changes in DPN pathology as a result of intervention. IMPLICATIONS: Noninvasive exercise intervention is particularly valuable in DPN because of its safety, low cost, and potential to augment pharmacologic interventions. As we gain a better mechanistic understanding of the disease, more targeted and effective interventions can be designed.

OBJECTIVE: To examine the relationship between plantar stress over a step, cumulative plantar stress over a day, and first metatarsophalangeal (MTP) joint pain among older adults. METHODS: Plantar stress and first MTP pain were assessed within the Multicenter Osteoarthritis Study. All included participants were asked if they had pain, aching, or stiffness at the first MTP joint on most days for the past 30 days. Pressure time integral (PTI) was quantified as participants walked on a pedobarograph, and mean steps per day were obtained using an accelerometer. Cumulative plantar stress was calculated as the product of regional PTI and mean steps per day. Quintiles of hallucal and second metatarsal PTI and cumulative plantar stress were generated. The relationship between predictors and the odds ratio of first MTP pain was assessed using a logistic regression model. RESULTS: Feet in the quintile with the lowest hallux PTI had 2.14 times increased odds of first MTP pain (95% confidence interval [95% CI] 1.42-3.25, P < 0.01). Feet in the quintile with the lowest second metatarsal PTI had 1.50 times increased odds of first MTP pain (95% CI 1.01-2.23, P = 0.042). Cumulative plantar stress was unassociated with first MTP pain. CONCLUSION: Lower PTI was modestly associated with increased prevalence of frequent first MTP pain at both the hallux and second metatarsal. Lower plantar loading may indicate the presence of an antalgic gait strategy and may reflect an attempt at pain avoidance. The lack of association with cumulative plantar stress may suggest that patients do not limit their walking as a pain-avoidance mechanism.

CONTEXT/BACKGROUND:Athletes who participate in throwing and racket sports consistently demonstrate adaptive changes in glenohumeral-joint internal and external rotation in the dominant arm. Measurements of these motions have demonstrated excellent intrarater and poor interrater reliability. OBJECTIVE:To determine intrarater reliability, interrater reliability, and standard error of measurement for shoulder internal rotation, external rotation, and total arc of motion using an inclinometer in 3 testing procedures in National Collegiate Athletic Association Division I baseball and softball athletes. DESIGN/METHODS:Cross-sectional study. SETTING/METHODS:Athletic department. PATIENTS OR OTHER PARTICIPANTS/METHODS:Thirty-eight players participated in the study. Shoulder internal rotation, external rotation, and total arc of motion were measured by 2 investigators in 3 test positions. The standard supine position was compared with a side-lying test position, as well as a supine test position without examiner overpressure. RESULTS:Excellent intrarater reliability was noted for all 3 test positions and ranges of motion, with intraclass correlation coefficient values ranging from 0.93 to 0.99. RESULTS for interrater reliability were less favorable. Reliability for internal rotation was highest in the side-lying position (0.68) and reliability for external rotation and total arc was highest in the supine-without-overpressure position (0.774 and 0.713, respectively). The supine-with-overpressure position yielded the lowest interrater reliability results in all positions. The side-lying position had the most consistent results, with very little variation among intraclass correlation coefficient values for the various test positions. CONCLUSIONS:The results of our study clearly indicate that the side-lying test procedure is of equal or greater value than the traditional supine-with-overpressure method.

Background: Footwear has a profound effect on walking speed, and lower extremity kinematics and kinetics. The purpose of this study is to identify possible predictors of walking speed and stride length in high- and low- heeled footwear. Methods: Thirty-one female subjects, each of whom were screened for lower extremity pain or dysfunction, and were determined not to be regular users of high-heeled shoes, participated in this study. Standardised, appropriately sized low- and high- heeled footwear were provided for all subjects. Euler angles were used to calculate the motion of the distal segment relative to the proximal segment. An inverse dynamics approach was used to calculate the net joint moment and power at the ankle, knee and hip joint. A paired t-test was used to assess the effect of footwear, and stepwise linear regression was performed to identify possible kinematic and kinetic predictors of walking speed and stride length. Results: Use of high-heeled footwear resulted in slower walking speed and shorter stride length. Regression analyses indicated that the most significant predictors of self-selected walking speed in high-heeled footwear were sagittal power generation at the knee, hip flexion, and sagittal power absorption at the ankle. Determinants of stride length when walking in high-heeled footwear included ankle sagittal power generation, hip sagittal range and the hip extension moment. Conclusion: A relatively simple model (three predictors or less) was able to explain 30-60% of the variance in walking speed and stride length. The key findings of our study underscore that altering heel height results in a change in motor strategy and attendant joint contribution used to maintain walking speed and stride length.

BACKGROUND:Low arch alignment and metatarsus primus elevatus (MPE) have been postulated to increase dorsal compressive stresses in the joints of the medial column of the foot and to contribute to the development of degenerative changes. The primary purposes of this study were (1) to examine the relationship between radiographic measures of arch alignment and MPE and (2) to assess arch alignment and MPE in individuals with midfoot arthritis and in asymptomatic controls. The secondary aim was to examine the reliability of radiographic measures of arch alignment and MPE. METHODS:Radiographic measures of arch height and MPE were quantified on 28 individuals with midfoot arthritis and 22 individuals in a control group. Reliability was assessed using the intraclass correlation coefficient (ICC). The Pearson product moment correlation (r) was used to assess the relationship between arch alignment and MPE. Between-group differences were assessed using a two-sample t test (α = 0.05). RESULTS:Good to excellent reliability was noted for measures of arch height (ICC[2,3] = 0.919-0.994) as well as MPE (ICC[2,3] = 0.891-0.882). A modest positive association was noted between normalized cortical elevation and normalized navicular height (r = 0.274, P = .030) and calcaneal inclination angle (r = 0.263, P = .035). Individuals with midfoot arthritis demonstrated lower arch alignment, reflected in a significantly higher calcaneal-first metatarsal angle (P = .002), lower calcaneal inclination angle (P = .004), and lower normalized navicular height (P < .001) compared with controls. No evidence was found to support between-group differences in lateral intermetatarsal angle (P = .495) and normalized cortical elevation (P = .146). CONCLUSIONS:These findings provide objective data establishing the reliability of measures of MPE and arch alignment and their potential clinical significance.

The purpose of this study was to compare estimates of gastrocnemius muscle length (GML) obtained using a segmented versus straight-line model in children. Kinematic data were acquired on eleven typically developing children as they walked under the following conditions: normal gait, crouch gait, equinus gait, and crouch with equinus gait. Maximum and minimum GML, and GML change were calculated using two models: straight-line and segmented. A two-way RMANOVA was used to compare GML characteristics. Results indicated that maximum GML and GML change during simulated pathological gait patterns were influenced by model used to calculate gastrocnemius muscle length (interaction: P = .004 and P = .026). Maximum GML was lower in the simulated gait patterns compared with normal gait (P < .001). Maximum GML was higher with the segmented model compared with the straight-line model (P = .030). Using either model, GML change in equinus gait and crouch with equinus gait was lower compared with normal gait (P < .001). Overall, minimum GML estimated with the segmented model was higher compared with the straight-line model (P < .01). The key findings of our study indicate that GML is significantly affected by both gait pattern and method of estimation. The GML estimates tended to be lower with the straight-line model versus the segmented model.