Achilles tendon assessment on quantitative MRI: Sources of variability and relationships to tendinopathy.

Quantitative MRI (qMRI) measures are useful in assessing musculoskeletal tissues, but application to tendon has been limited. The purposes of this study were to optimize, identify sources of variability, and establish reproducibility of qMRI to assess Achilles tendon. Additionally, preliminarily estimates of effect of tendon pathology on qMRI metrics and structure-function relationships between qMRI measures and ankle performance were examined. T1, T1ρ, T2, and T2* maps of the Achilles tendon were obtained using a 3T MRI scanner. In participants with asymptomatic tendons (n = 21), MRI procedures were repeated twice, and region of interest selection was performed by three raters. Variance decomposition and reproducibility statistics were completed. To estimate the effect of pathology, qMRI measures from individuals with asymptomatic tendons were compared to qMRI measures from a pilot group of individuals with Achilles tendinopathy (n = 7). Relationships between qMRI and ankle performance measures were assessed. Between-participant variation accounted for the majority of variability (46.7%-64.0%) in all qMRI measures except T2*. ICCs met or exceeded 0.7 for all qMRI measures when averaged across raters or scans. Relaxation times were significantly longer in tendinopathic tendons (mean (SD) T1: 977.8 (208.6) ms, T1ρ: 35.4 (7.1) ms, T2: 42.8 (7.9) ms, T2*: 14.1 (7.6) ms, n = 7) compared to asymptomatic control tendons (T1: 691.7 (32.4) ms, T1ρ: 24.0 (3.6) ms, T2: 24.4 (7.5) ms, T2*: 9.5 (3.4) ms, n = 21) (p < 0.011 for all comparisons). T1 related to functional performance measures in symptomatic and asymptomatic groups. Study findings suggest that qMRI is reliable to assess the Achilles tendon. qMRI quantitatively assesses the presence of tendon pathology and relates to functional performance outcomes, supporting the utility of incorporating qMRI in research and clinic.

Minimal effect of scanning parameters on ultrasound shear wave elastography variability in tendons.

PURPOSE: Ultrasound shear wave elastography has potential use in assessing tendon tissue; however, reducing measurement variability remains challenging. The primary purpose of this study was to identify the amount of variability accounted for by ultrasound parameter (frequency, harmonics and CrossXBeam) settings on shear wave speed at two testing sites. METHODS: Shear wave elastography images of the Achilles tendon were obtained from individuals with healthy tendons (n = 28) at two testing sites with standardised image acquisition/postprocessing protocols. Images were acquired at a range of frequencies (7-15 MHz) with CrossXBeam (a filtering technique) and harmonics settings toggled on and off. Variance decomposition analysis was performed to identify the amount of variability in shear wave speed accounted for by scan acquisition settings and testing sites. RESULTS: Shear wave speed variance was primarily attributed to participants (56.87% of variance; residual error: 35%). All scanning parameters, testing site and interaction terms each accounted for less than 2.5% of the variance. A statistically significant, negative relationship was observed between shear wave speed and image quality (p = 0.001) suggesting poor image quality yields higher shear wave speed estimates. CONCLUSION: The findings of this study suggest that natural variation in Achilles tendon mechanics between individuals without tendon pathology accounts for most of the shear wave speed variability. Optimising image quality, which may be observed in higher frequencies, should be considered to improve shear wave speed estimation. Clinically, this study highlights the need to take multiple images, maintain consistent ultrasound settings when tracking patient progress over time and use caution when comparing raw values from tendon scans performed in different clinics with shear wave elastography. LEVEL OF EVIDENCE: Level III.

Regional skeletal muscle perfusion distribution in diabetic feet may differentiate short-term healed foot ulcers from non-healed ulcers.

OBJECTIVES: The purpose of this study was to leverage a magnetic resonance imaging (MRI) approach to characterize foot perfusion distribution in patients with diabetes, with or without foot ulcers, and determine the ability of the regional perfusion measurements to identify ulcer-healing status. METHODS: Three groups of participants (n = 15 / group) were recruited: controls (without diabetes), type II diabetes, and type II diabetes with foot ulcers. All participants underwent MRI evaluating foot perfusion in three muscle layers (from plantar to dorsal) at rest and during a standardized toe-flexion exercise. The exercise perfusion and perfusion reserve values were analyzed around and away from ulcers. Participants with foot ulcers were followed up 3 months after the MRI exams to determine the foot healing status. RESULTS: Foot plantar muscle perfusion reserves were progressively lower from controls to diabetes, and to diabetes with foot ulcers (e.g., 2.58 ± 0.67, 1.48 ± 0.71, 1.12 ± 0.35, p < 0.001). In controls, the plantar layer had significantly higher perfusion reserve than the dorsal layer, whereas in either diabetes group, there was no significant difference in perfusion reserve among muscle layers. Using the ratio of total exercise perfusion around ulcers to that away from ulcers, the sensitivity and specificity to differentiate healing from non-healed ulcers were 100% and 86%, respectively. CONCLUSIONS: Our study reveals significantly different foot perfusion distribution among controls, diabetes, and diabetes with foot ulcers. The prognostic value of MRI regional perfusion assessments has the potential to monitor interventions to improve ulcer healing outcomes. KEY POINTS: • Contrast-free MRI permits quantitative assessment of regional foot muscle perfusion at rest and during isometric exercise. • Patients with diabetes and foot ulcers, without clinical evidence of peripheral arterial disease, had significantly impaired foot muscle perfusion and perfusion reserve. • Regional foot perfusion distribution may be used to predict the short-term healing status of foot ulcers in diabetes.

Achilles tendon cross-sectional area at 12 weeks post-rupture relates to 1-year heel-rise height.

PURPOSE: Achilles tendon rupture leads to long-term plantar flexor deficits, but some patients recover functional performance better than others. Early indicators of tendon healing could be helpful in establishing patient prognosis and making individualized decisions regarding rehabilitation progression. The purpose of this study was to investigate relationships between early tendon morphology and mechanical properties to long-term heel-rise and jumping function in individuals after Achilles tendon rupture. METHODS: Individuals after Achilles tendon rupture were assessed at 4, 8, 12, 24, and 52 weeks post-injury. Tendon cross-sectional area, length, and mechanical properties were measured using ultrasound. Heel-rise and jump tests were performed at 24 and 52 weeks. Correlation and regression analysis were used to identify relationships between tendon structural variables in the first 12 weeks to functional outcomes at 52 weeks, and determine whether the addition of tendon structural characteristics at 24 weeks strengthened relationships between functional performance at 24 and 52 weeks. Functional outcomes of individuals with < 3 cm of elongation were compared to those with > 3 cm of elongation using a Mann-Whitney U test. RESULTS: Twenty-two participants [mean (SD) age = 40 (11) years, 17 male] were included. Tendon cross-sectional area at 12 weeks was the strongest predictor of heel-rise height (R2 = 0.280, p = 0.014) and work symmetry (R2 = 0.316, p = 0.008) at 52 weeks. Jumping performance at 52 weeks was not significantly related to any of the tendon structural measures in the first 12 weeks. Performance of all functional tasks at 24 weeks was positively related to performance on the same task at 52 weeks (r = 0.456-0.708, p < 0.05). The addition of tendon cross-sectional area improved the model for height LSI (R2 = 0.519, p = 0.001). Tendon elongation > 3 cm significantly reduced jumping symmetry (p < 0.05). CONCLUSION: Tendon cross-sectional area and excessive elongation related to plantar flexor performance on functional testing after Achilles tendon rupture. Once an individual is able to perform function-based testing, tendon structural measures may inform long-term prognosis. Ultrasound-based measures of tendon structure early in recovery seem to relate to later performance on functional testing. Clinically, assessing tendon structure has the potential to be used as a biomarker of tendon healing early in recovery and better predict patients at risk of negative functional outcome. LEVEL OF EVIDENCE: II.

No difference in strength and clinical outcome between early and late repair after Achilles tendon rupture.

PURPOSE: This retrospective study aimed to determine the patient-reported and functional outcome of patients with delayed presentation, who had received no treatment until 14 days following injury of Achilles tendon rupture repaired with minimally invasive surgery and were compared with a group of sex- and age-matched patients presenting acutely. Based on the outcomes following delayed presentation reported in the literature, it was hypothesized that outcomes would be inferior for self-reported outcome, tendon elongation, heel-rise performance, ability to return to play, and complication rates than for acutely managed patients. METHODS: Repair was performed through an incision large enough to permit mobilisation of the tendon ends, core suture repair consisting of a modified Bunnell suture proximally and a Kessler suture distally and circumferential running suture augmentation. RESULTS: Nine patients presented 21.8 (14.9) days (range 14-42 days) after rupture. The rate of delayed presentation was estimated to be 1 in 10. At 12 months following repair, patients with delayed treatment had median (range) ATRS score of 90 (69-99) compared with 94 (75-100) in patients treated acutely presenting 0.66 (1.7) (0-5) days. There were no significant differences between groups: ATRA [mean (SD) delayed: - 6.9° (5.5), acute: - 6° (4.7)], heel-rise height index [delayed: 79% (20), acute: 74% (14)], or heel-rise repetition index [delayed: 77% (20), acute: 71% (20)]. In the delayed presentation group, two patients had wound infection and one iatrogenic sural nerve injury. CONCLUSIONS: Patients presenting more than 2 weeks after Achilles tendon rupture may be successfully treated with minimally invasive repair. LEVEL OF EVIDENCE: III.

Tendon morphology and mechanical properties assessed by ultrasound show change early in recovery and potential prognostic ability for 6-month outcomes.

PURPOSE: Optimizing tendon structural recovery during the first 12 weeks after Achilles tendon rupture is a prime target to improve patient outcomes, but a comprehensive understanding of biomarkers is needed to track early healing. The purpose of this study was to observe healing of tendon structure over time using ultrasound-based, tendon-specific measures and to identify relationships between tendon structural characteristics and clinical measures of gait and strength. METHODS: Twenty-seven participants (21 males, mean (SD) age 39 (11) years) were assessed at 4, 8, 12, and 24 weeks after injury or surgery using ultrasound imaging techniques. Gait analysis and strength testing were added at the later time points. RESULTS: Ruptured tendons had significantly lower dynamic shear modulus (p < 0.001), greater tendon cross-sectional area (p < 0.001), and greater length (p < 0.001) than the uninjured side. Dynamic shear modulus, cross-sectional area, and length were found to increase over time (p < 0.01). Tendon structure at 4 weeks post-injury [cross-sectional area symmetry (r = 0.737, p = 0.002) and dynamic shear modulus (r = 0.518, p = 0.040)] related to stance phase walking symmetry at 24 weeks. CONCLUSIONS: Tendon structure assessed by ultrasound imaging changes over the first 24 weeks of healing after Achilles tendon rupture, suggesting it could be used as a biomarker to track tendon healing early in recovery. Additionally, tendon structure within the first 12 weeks relates to later walking gait and heel-rise symmetry, which may indicate that tendon structure could have prognostic value in the care of these patients. This study's clinical relevance is in its support for using ultrasound imaging to assess early patient healing and prognosticate later patient outcomes after Achilles tendon rupture. LEVEL OF EVIDENCE: Level 2, prospective cohort prognostic study.

Return to play post-Achilles tendon rupture: a systematic review and meta-analysis of rate and measures of return to play.

AIM: This systematic review and meta-analysis sought to identify return to play (RTP) rates following Achilles tendon rupture and evaluate what measures are used to determine RTP. DESIGN: A systematic review and meta-analysis were performed. Studies were assessed for risk of bias and grouped based on repeatability of their measure of RTP determination. DATA SOURCES: PubMed, CINAHL, Web of Science and Scopus databases were searched to identify potentially relevant articles. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Studies reporting RTP/sport/sport activity in acute, closed Achilles tendon rupture were included. RESULTS: 108 studies encompassing 6506 patients were included for review. 85 studies included a measure for determining RTP. The rate of RTP in all studies was 80% (95% CI 75% to 85%). Studies with measures describing determination of RTP reported lower rates than studies without metrics described, with rates being significantly different between groups (p<0.001). CONCLUSIONS: 80 per cent of patients returned to play following Achilles tendon rupture; however, the RTP rates are dependent on the quality of the method used to measure RTP. To further understand RTP after Achilles tendon rupture, a standardised, reliable and valid method is required.

Feasibility of an early progressive resistance exercise program for acute Achilles tendon rupture.

BACKGROUND: Long-term strength deficits are common after Achilles tendon ruptures. Early use of progressive resistance exercises may help reduce strength deficits, but the feasibility of this approach is unknown. The aim was to investigate the feasibility of early progressive resistance exercises regarding patient acceptability and compliance with the intervention. METHODS: We recruited patients with an acute Achilles tendon rupture treated non-surgically. During 9 weeks of immobilisation with a walking boot, participants attended weekly supervised physiotherapy sessions of progressive resistance exercises and performed home exercises, consisting of isometric ankle plantarflexion, seated heel-rise, and elastic band exercises. Acceptability was evaluated using a 7-point Likert scale (1 = very unacceptable and 7 = very acceptable) with feasibility threshold at 80% of the participants rating ≥ 4. Adherence to the exercises was defined as 80% of the participants performing at least 50% of the home exercises. During the intervention, tendon healing and adverse events were monitored. RESULTS: Sixteen participants (mean age 46 (range 28-61), male/female = 13/3) completed the intervention. Pre-injury Achilles tendon total rupture score was 98 (SD 8). All participants rated the acceptability of the exercises ≥ 5 (moderate acceptable to very acceptable) at 9- and 13-week follow-up and 9/16 rated 7 points (very acceptable). Participants performed 74% (range 4-117) of the total prescribed home exercises and 15/16 performed > 50%. One participant was not compliant with the home exercises due to feeling uncomfortable performing these independently. There were no re-ruptures, but one case of deep venous thrombosis. CONCLUSIONS: The early progressive resistance exercise program for treatment of non-surgically treated Achilles tendon rupture was feasible. Future studies should investigate the efficacy of the progressive intervention. TRIAL REGISTRATION: The study was registered at Clinical Trials (NCT04121377) on 29 September 2019. CLINICALTRIALS: NCT04121377 .

Use of computed tomography to identify muscle quality subgroups, spatial mapping, and preliminary relationships to function in those with diabetic peripheral neuropathy.

BACKGROUND: Decreased muscle volume and increased muscle-associated adipose tissue (MAAT, sum of intra and inter-muscular adipose tissue) of the foot intrinsic muscle compartment are associated with deformity, decreased function, and increased risk of ulceration and amputation in those with diabetic peripheral neuropathy (DPN). RESEARCH QUESTION: What is the muscle quality (normal, abnormal muscle, and adipose volumes) of the DPN foot intrinsic compartment, how does it change over time, and is muscle quality related to gait and foot function? METHODS: Computed tomography was performed on the intrinsic foot muscle compartment of 45 subjects with DPN (mean age: 67.2 ± 6.4 years) at baseline and 3.6 years. Images were processed to obtain volumes of MAAT, highly abnormal, mildly abnormal, and normal muscle. For each category, annual rates of change were calculated. Paired t-tests compared baseline and follow-up. Foot function during gait was assessed using 3D motion analysis and the Foot and Ankle Ability Measure. Correlations between muscle compartment and foot function during gait were analyzed using Pearson's correlations. RESULTS: Total muscle volume decreased, driven by a loss of normal muscle and mildly abnormal muscle (p<0.05). MAAT and the adipose-muscle ratio increased. At baseline, 51.5% of the compartment was abnormal muscle or MAAT, increasing to 55.0% at follow-up. Decreased total muscle volume correlated with greater midfoot collapse during gait (r = -0.40, p = 0.02). Greater volumes of highly abnormal muscle correlated with a lower FAAM score (r = -0.33, p = 0.03). SIGNIFICANCE: Muscle volume loss may progress in parallel with MAAT accumulation, impacting contractile performance in individuals with DPN. Only 48.5% of the DPN intrinsic foot muscle compartment consists of normal muscle and greater abnormal muscle is associated with worse foot function. These changes identify an important target for rehabilitative intervention to slow or prevent muscle deterioration and poor foot outcomes.

Effect of Diabetes on Tendon Structure and Function: Not Limited to Collagen Crosslinking.

Diabetes mellitus (DM) is associated with musculoskeletal complications-including tendon dysfunction and injury. Patients with DM show altered foot and ankle mechanics that have been attributed to tendon dysfunction as well as impaired recovery post-tendon injury. Despite the problem of DM-related tendon complications, treatment guidelines specific to this population of individuals are lacking. DM impairs tendon structure, function, and healing capacity in tendons throughout the body, but the Achilles tendon is of particular concern and most studied in the diabetic foot. At macroscopic levels, asymptomatic, diabetic Achilles tendons may show morphological abnormalities such as thickening, collagen disorganization, and/or calcific changes at the tendon enthesis. At smaller length scales, DM affects collagen sliding and discrete plasticity due to glycation of collagen. However, how these alterations translate to mechanical deficits observed at larger length scales is an area of continued investigation. In addition to dysfunction of the extracellular matrix, tendon cells such as tenocytes and tendon stem/progenitor cells show significant abnormalities in proliferation, apoptosis, and remodeling capacity in the presence of hyperglycemia and advanced glycation end-products, thus contributing to the disruption of tendon homeostasis and healing. Improving our understanding of the effects of DM on tendons-from molecular pathways to patients-will progress toward targeted therapies in this group at high risk of foot and ankle morbidity.

Remote Research: Resources, Intervention Needs, and Methods in People with Diabetes and Peripheral Neuropathy.

BACKGROUND: Stay-at-home orders associated with the SARS-CoV-2 (COVID-19) pandemic were particularly important for older adults with type 2 diabetes, at risk for severe COVID-19 complications. In response, research shifted to remote telehealth methodology. Study participant interests, equipment needs, and ability to adapt methods to the remote/telehealth environment were unknown. Study purposes to assess (1) resource needs (internet/devices accessibility), (2) future telehealth interests, and (3) ability to adapt common research and clinical measures of glycemic control, physical function, activity measures, and quality of life outcomes to a telehealth setting. METHOD: Twenty-one participants with type 2 diabetes and peripheral neuropathy were recruited from a longitudinal study (11 female; age: 66.3 ± 8.3 years; DM: 15.1 ± 8.7 years). Technology needs and future telehealth interests were assessed. A glycemic measure (HbA1c), a five-times chair rise, a one-week activity monitor, and surveys (self-efficacy, depression, and balance) were collected. All aspects of the study were completed remotely over email and video/phone call. RESULTS: Twelve participants used computers; nine used phones for study completion. Participants had the following resource needs: connectivity (n = 3), devices (n = 6), and technical support (n = 12). Twenty people expressed interest in participating in future telehealth studies related to balance, exercise, and diabetes management. Methodological considerations were primarily the need for assistance for participants to complete the home HbA1c test, five-time chair rise, wearable activity monitoring, and surveys. CONCLUSIONS: Older adults with type 2 diabetes and peripheral neuropathy would need technological and personal assistance (connection, device, guidance) to complete a long-term telehealth intervention. Despite technology needs, participants were interested in telehealth interventions. CLINICAL TRIAL: Parent study, "Metatarsal Phalangeal Joint Deformity Progression-R01 (NCT02616263) is registered at https://clinicaltrials.gov/.

Rate of tarsal and metatarsal bone mineral density change in adults with diabetes mellitus and peripheral neuropathy: a longitudinal study.

BACKGROUND: In people with diabetes (DM) and peripheral neuropathy (PN), loss of bone mineral density (BMD) in the tarsals and metatarsals contribute to foot complications; however, changes in BMD of the calcaneal bone is most commonly reported. This study reports rate of change in BMD of all the individual bones in the foot, in participants with DM and PN. Our aim was to investigate whether the rate of BMD change is similar across all the bones of the foot. METHODS: Participants with DM and PN (n = 60) were included in this longitudinal cohort study. Rate of BMD change of individual bones was monitored using computed tomography at baseline and 6 months, 18 months, and 3-4 years from baseline. Personal factors (age, sex, medication use, step count, sedentary time, and PN severity) were assessed. A random coefficient model estimated rate of change of BMD in all bones and Pearson correlation tested relationships between personal factor variables and rate of BMD change. RESULTS: Mean and calcaneal BMD decreased over the study period (p < 0.05). Individual tarsal and metatarsal bones present a range of rate of BMD change (-0.3 to -0.9%/year) but were not significantly different than calcaneal BMD change. Only age showed significant correlation with BMD and rate of BMD change. CONCLUSION: The rate of BMD change did not significantly differ across different foot bones at the group level in people with DM and PN without foot deformity. Asymmetric BMD loss between individual bones of the foot and aging may be indicators of pathologic changes and require further investigation. TRIAL REGISTRATION: Metatarsal Phalangeal Joint Deformity Progression-R01. Registered 25 November 2015, https://clinicaltrials.gov/ct2/show/NCT02616263.

Fascicular elastin within tendon contributes to the magnitude and modulus gradient of the elastic stress response across tendon type and species.

Elastin, the main component of elastic fibers, has been demonstrated to significantly influence tendon mechanics using both elastin degradation studies and elastinopathic mouse models. However, it remains unclear how prior results differ between species and functionally distinct tendons and, in particular, how results translate to human tendon. Differences in function between fascicular and interfascicular elastin are also yet to be fully elucidated. Therefore, this study evaluated the quantity, structure, and mechanical contribution of elastin in functionally distinct tendons across species. Tendons with an energy-storing function had slightly more elastin content than tendons with a positional function, and human tendon had at least twice the elastin content of other species. While distinctions in the organization of elastic fibers between fascicles and the interfascicular matrix were observed, differences in structural arrangement of the elastin network between species and tendon type were limited. Mechanical testing paired with enzyme-induced elastin degradation was used to evaluate the contribution of elastin to tendon mechanics. Across all tendons, elastin degradation affected the elastic stress response by decreasing stress values while increasing the modulus gradient of the stress-strain curve. Only the contributions of elastin to viscoelastic properties varied between tendon type and species, with human tendon and energy-storing tendon being more affected. These data suggest that fascicular elastic fibers contribute to the tensile mechanical response of tendon, likely by regulating collagen engagement under load. Results add to prior findings and provide evidence for a more mechanistic understanding of the role of elastic fibers in tendon. STATEMENT OF SIGNIFICANCE: Elastin has previously been shown to influence the mechanical properties of tendon, and degraded or abnormal elastin networks caused by aging or disease may contribute to pain and an increased risk of injury. However, prior work has not fully determined how elastin contributes differently to tendons with varying functional demands, as well as within distinct regions of tendon. This study determined the effects of elastin degradation on the tensile elastic and viscoelastic responses of tendons with varying functional demands, hierarchical structures, and elastin content. Moreover, volumetric imaging and protein quantification were used to thoroughly characterize the elastin network in each distinct tendon. The results presented herein can inform tendon-specific strategies to maintain or restore native properties in elastin-degraded tissue.

Quantative MRI predicts tendon mechanical behavior, collagen composition, and organization.

Quantitative magnetic resonance imaging (qMRI) measures have provided insights into the composition, quality, and structure-function of musculoskeletal tissues. Low signal-to-noise ratio has limited application to tendon. Advances in scanning sequences and sample positioning have improved signal from tendon allowing for evaluation of structure and function. The purpose of this study was to elucidate relationships between tendon qMRI metrics (T1, T2, T1ρ and diffusion tensor imaging [DTI] metrics) with tendon tissue mechanics, collagen concentration and organization. Sixteen human Achilles tendon specimens were collected, imaged with qMRI, and subjected to mechanical testing with quantitative polarized light imaging. T2 values were related to tendon mechanics [peak stress (rsp = 0.51, p = 0.044), equilibrium stress (rsp = 0.54, p = 0.033), percent relaxation (rsp = -0.55, p = 0.027), hysteresis (rsp = -0.64, p = 0.007), linear modulus (rsp = 0.67, p = 0.009)]. T1ρ had a statistically significant relationship with percent relaxation (r = 0.50, p = 0.048). Collagen content was significantly related to DTI measures (range of r = 0.56-0.62). T2 values from a single slice of the midportion of human Achilles tendons were strongest predictors of tendon tensile mechanical metrics. DTI diffusivity indices (mean diffusivity, axial diffusivity, radial diffusivity) were strongly correlated with collagen content. These findings build on a growing body of literature supporting the feasibility of qMRI to characterize tendon tissue and noninvasively measure tendon structure and function. Statement of Clinical Significance: Quantitative MRI can be applied to characterize tendon tissue and is a noninvasive measure that relates to tendon composition and mechanical behavior.

Midfoot and ankle movement coordination during heel rise is disrupted in people with diabetes and peripheral neuropathy.

BACKGROUND: A heel rise task can be used to evaluate midfoot and ankle movement dysfunction in people with diabetes mellitus and peripheral neuropathy. Quantifying movement coordination during heel rise is important to better understand potentially detrimental movement strategies in people with foot pathologies; however, coordination and the impact of limited excursion on coordination is not well-understood in people with diabetes. METHODS: Sixty patients with diabetes mellitus and peripheral neuropathy, and 22 older and 25 younger controls performed single-limb heel rise task. Midfoot (forefoot relative to hindfoot) sagittal and ankle (hindfoot relative to shank) sagittal and frontal kinematics were measured and normalized to time (0 to 100%). Cross-correlation coefficients were calculated across individuals in each group. A graphical illustration was used to interpret the relationship of midfoot and ankle excursion and cross-correlation coefficient during heel rise. FINDINGS: People with diabetes mellitus and peripheral neuropathy showed significantly lower midfoot and ankle cross-correlation coefficients during heel rise compared to older controls (p = 0.003-0.007). There was no difference in the midfoot and ankle cross-correlation coefficients during heel rise for the older and younger controls (p = 0.059-0.425). The graphic data illustrated a trend of greater excursion of two joints and a higher cross-correlation coefficient. Some individuals with lower excursion showed a high cross-correlation coefficient. INTERPRETATION: Foot pathologies, but not aging, impairs midfoot and ankle movement coordination during heel rise task. Investigating both movement coordination as well as joint excursion would better inform and characterize the dynamic movements of midfoot and ankle during heel rise task.

Body mass index and maximum available midfoot motion are associated with midfoot angle at peak heel rise in people with type 2 diabetes mellitus and peripheral neuropathy.

PURPOSE: Midfoot movement dysfunction, as measured by heel rise performance, is associated with midfoot deformity in people with diabetes and peripheral neuropathy. Understanding contributors of midfoot movement dysfunction may help clinicians understand deformity progression. The purpose of this study was to determine the factors associated with midfoot angle at peak heel rise. METHODS: The outcomes of fifty-eight participants with type 2 diabetes mellitus and peripheral neuropathy were analyzed. Midfoot (forefoot on hindfoot) sagittal kinematics during unilateral heel rise task were measured using 3-dimensional motion analysis. A multivariate linear regression model was used to predict midfoot sagittal movements at peak heel rise. Independent variables that were entered in the model were (in order of entry): age, body mass index, intrinsic foot muscle volume, and maximum available midfoot plantarflexion range of motion. Intrinsic foot muscle volume was obtained from magnetic resonance imaging and maximum available midfoot motion was measured during non-weightbearing plantarflexion using 3-dimensional motion analysis. RESULTS: Body mass index (R2 = 30.5%, p < 0.001) and maximum available midfoot plantarflexion range of motion (R2 = 10.9%, p = 0.001) were significant factors that accounted for 41.4% of variance of midfoot angle at peak heel rise, while age and intrinsic foot muscle volume were not significant predictors. CONCLUSIONS: Greater body mass index and less available midfoot plantarflexion range of motion were associated with greater midfoot movement dysfunction. These two significant predictors are potentially modifiable, suggesting possible improvements in midfoot movements with reduction in body weight and increasing midfoot plantarflexion range of motion. Health care professionals should consider patient's weight and joint motion when prescribing foot exercise(s) to prevent excessive midfoot collapse during weightbearing tasks.

Functional Ankle Range of Motion but Not Peak Achilles Tendon Force Diminished With Heel-Rise and Jumping Tasks After Achilles Tendon Repair.

BACKGROUND: Deficits in sporting performance after Achilles tendon repair may be due to changes in musculotendinous unit structure, including tendon elongation and muscle fascicle shortening. PURPOSE/HYPOTHESIS: The purpose was to discern whether Achilles tendon rupture reduces triceps surae muscle force generation, alters functional ankle range of motion, or both during sports-related tasks. We hypothesized that individuals who have undergone Achilles tendon repair lack the functional ankle range of motion needed to complete sports-related tasks. STUDY DESIGN: Descriptive laboratory study. METHODS: The study included individuals 1 to 3 years after treatment of Achilles tendon rupture with open repair. Participants (n = 11) completed a heel-rise task and 3 jumping tasks. Lower extremity biomechanics were analyzed using motion capture. Between-limb differences were tested using paired t test. RESULTS: Pelvic vertical displacement was reduced during the heel-rise (mean difference, -12.8%; P = .026) but not during the jumping task (P > .1). In the concentric phase of all tasks, peak ankle plantarflexion angle (range of mean difference, -19.2% to -48.8%; P < .05) and total plantar flexor work (defined as the area under the plantar flexor torque - ankle angle curve) (range of mean difference, -9.5% to -25.7%; P < .05) were lower on the repaired side relative to the uninjured side. No significant differences were seen in peak Achilles tendon load or impulse with any of the tasks. There were no differences in plantar flexor work or Achilles tendon load parameters during eccentric phases. CONCLUSION: Impaired task performance or increased demands on proximal joints were observed on the repaired side in tasks isolating ankle function. Tasks that did not isolate ankle function appeared to be well recovered, although functional ankle range of motion was reduced with rupture. Reduced plantar flexor muscle-tendon unit work supports previous reports that an elongated tendon and shorter muscle fascicles caused by Achilles tendon rupture constrain functional capacity. Achilles tendon peak load and impulse were not decreased, suggesting that reduced and shifted functional ankle range of motion (favoring dorsiflexion) underlies performance deficits. CLINICAL RELEVANCE: These findings point to the need to reduce tendon elongation and restore muscle length of the triceps surae after Achilles tendon rupture in order to address musculature that is short but not necessarily weak for improved performance with sports-related activities.

Midfoot and ankle motion during heel rise and gait are related in people with diabetes and peripheral neuropathy.

BACKGROUND: Midfoot and ankle movement dysfunction in people with diabetes mellitus and peripheral neuropathy (DMPN) is associated with midfoot deformity and increased plantar pressures during gait. If midfoot and ankle motion during heel rise and push-off of gait have similar mechanics, heel rise performance could be a clinically feasible way to identify abnormal midfoot and ankle function during gait. RESEARCH QUESTION: Is midfoot and ankle joint motion during a heel rise associated with midfoot and ankle motion at push-off during gait in people with DMPN? METHODS: Sixty adults with DMPN completed double-limb heel rise, single-limb heel rise, and walking. A modified Oxford multi-segment foot model (forefoot, hindfoot, shank) was used to analyze midfoot (forefoot on hindfoot) and ankle (hindfoot on shank) sagittal angle during heel rise and gait. Pearson correlation was used to test the relationship between heel rise and gait kinematic variables (n = 60). Additionally, we classified 60 participants into two subgroups based on midfoot and ankle position at peak heel rise: midfoot and ankle dorsiflexed (dorsiflexed; n = 23) and midfoot and ankle plantarflexed (plantarflexed; n = 20). Movement trajectories of midfoot and ankle motion during single-limb heel rise and gait of the subgroups were examined. RESULTS: Peak double-limb heel rise and gait midfoot and ankle angles were significantly correlated (r = 0.49 and r = 0.40, respectively). Peak single-limb heel rise and gait midfoot and ankle angles were significantly correlated (r = 0.63 and r = 0.54, respectively). The dorsiflexed subgroup, identified by heel rise performance showed greater midfoot and ankle dorsiflexion during gait compared to the plantarflexed subgroup (mean difference between subgroups: midfoot 3°, ankle 3°). SIGNIFICANCE: People with DMPN who fail to plantarflex the midfoot and ankle during heel rise have difficulty plantarflexing the midfoot and ankle during gait. Utilizing a heel rise task may help identify midfoot and ankle dysfunction associated with gait in people with DMPN.

A limited number of slices yields comparable results to all slices in foot intrinsic muscle deterioration ratio on computed tomography and magnetic resonance imaging.

Diagnostic imaging modalities, like computed tomography (CT) and magnetic resonance imaging (MRI), can be used to assess in vivo muscle quality. Quantitative assessment using these techniques is time-intensive and costly due in part to extensive post-processing needs. The purpose of this study was to identify whether a subset of slices on CT and MRI would yield comparable results to the full number of slices for a measure of muscle quality (muscle deterioration ratio = fat volume/muscle volume) in the foot intrinsic muscles of people with diabetes and peripheral neuropathy. CT (0.6 mm slice thickness) and MRI (3.5 mm slice thickness) scans were obtained using previously described methods. The total number of slices acquired during the scan was compared to several conditions using a portion of slices. Bland-Altman plots and Lin's concordance correlation coefficient were used to test agreement. Any condition using at least three slices yielded substantial to almost perfect agreement with the total number of slices on both CT and MRI (Range of Lin's concordance correlation coefficient: 0.947-0.999). Using a single slice in the middle of the region of interest demonstrated poor to moderate agreement with the total number of slices. The findings of this study suggest that using a limited number of slices to quantify muscle deterioration ratio on CT or MRI is a viable way to balance the combined need for measurement accuracy with feasibility in research and clinical settings.

Heel Rise and Non-Weight-Bearing Ankle Plantar Flexion Tasks to Assess Foot and Ankle Function in People With Diabetes Mellitus and Peripheral Neuropathy.

OBJECTIVE: The objective of this study was to examine the effects of diabetes mellitus and peripheral neuropathy (DMPN), limited joint mobility, and weight-bearing on foot and ankle sagittal movements and characterize the foot and ankle position during heel rise. METHODS: Sixty people with DMPN and 22 controls participated. Primary outcomes were foot (forefoot on hindfoot) and ankle (hindfoot on shank) plantar-flexion/dorsiflexion angle during 3 tasks: unilateral heel rise, bilateral heel rise, and non-weight-bearing ankle plantar flexion. A repeated-measures analysis of variance and Fisher exact test were used. RESULTS: Main effects of task and group were significant, but not the interaction in both foot and ankle plantar flexion. Foot and ankle plantar flexion were less in people with DMPN compared with controls in all tasks. Both DMPN and control groups had significantly less foot and ankle plantar flexion with greater weight-bearing; however, the linear trend across tasks was similar between groups. The DMPN group had a greater percentage of individuals in foot and/or ankle dorsiflexion at peak unilateral heel rise compared with controls, but the foot and ankle position was similar at peak bilateral heel rise between DMPN and control groups. CONCLUSION: Foot and ankle plantar flexion is less in people with DMPN. Less plantar flexion in non-weight-bearing suggests that people with DMPN have limited joint mobility. However, peak unilateral and bilateral heel rise is less than the available plantar flexion range of motion measured in non-weight-bearing, indicating that limited joint mobility does not limit heel rise performance. A higher frequency of people with DMPN are in foot and ankle dorsiflexion at peak unilateral heel rise compared with controls, but the position improved with lower weight-bearing. IMPACT: Proper resistance should be considered with physical therapist interventions utilizing heel rise because foot and ankle plantar flexion position could be improved by reducing the amount of weight-bearing.