Current treatment concepts for Achilles tendon rupture.

Achilles tendon rupture is a common and primary cause of lower limb tendon injury suffered during sports-related activities. The causes of Achilles tendon rupture include the calf muscle and tendon overuse, poor tendon quality, and various medical conditions. Historically, acute Achilles tendon rupture was treated conservatively. However, historical techniques are now associated with an increased risk of rerupture. To address this problem, open repair has been proposed. Open repair is associated with a reduced risk of rerupture; however, it is also closely associated with wound complications, like wound infection, whose treatment is time-consuming and costly. Therefore, minimally invasive Achilles tendon repair has been proposed as a promising option with acceptable functional outcomes. Nevertheless, despite its benefits, minimally invasive Achilles tendon repair is associated with increased risks of sural nerve injury and rerupture. In this review, we evaluate the currently used treatment strategies for acute Achilles tendon rupture and their historical evolution to provide evidence-based recommendations for physicians.

Stability of contour augmentation of implant-supported single crowns in the esthetic zone: One-year cone-beam computed tomography results of a comparative, randomized, prospective, two-center clinical study using two different bone grafting techniques in early implant placement.

BACKGROUND: Early implant placement with contour augmentation could provide support and volume to the hard and soft tissues. Herein, we aimed to ascertain whether freeze-dried bone allograft (FDBA) shares with deproteinized bovine bone material (DBBM) the results for esthetic outcomes for anterior teeth and stability of peri-implant facial bone thickness and height by conducting guided bone regeneration. METHODS: Forty-eight patients were randomly assigned into two groups. In the control group, autogenous bone chips was used to cover the exposed implant surface, followed by a layer of DBBM. This graft combination was then covered with two layers of collagen membrane. In the test group, the exposed implant surface was covered with FDBA, combined with the collagen membrane. During this study, the hard tissue dimensional changes were measured at 12-months post-implant loading by using cone-beam computed tomography. RESULTS: At 12 months postoperatively, all 48 implants were clinically successful. The mean thickness of facial bone walls ranged from 1.6 to 2.45 mm at the three levels of measurement in the control group and ranged from 1.6 to 2.10 mm in the test group. The mean facial vertical bone wall peak (IP-FC) after loading 1 year presented with values of 0.8 mm (range, 0.0 to 1.25 mm) and 0.5 mm (range, 0.1 to 1.1 mm) coronal to the implant platform in control and test implants, respectively. There were no significant differences in facial bone wall thickness and IP-FC between groups. CONCLUSIONS: This study demonstrated that autogenous bone chips plus DBBM or FDBA showed similar outcome of peri-implant buccal bone stability in early implant placement after 1 year.

Biomechanical Effects of Plastic Heel Cup on Plantar Fasciitis Patients Evaluated by Ultrasound Shear Wave Elastography.

The plastic heel cup has been adopted to treat plantar heel problems for years. However, its mechanisms and biomechanical effects are yet to be fully understood. The purpose of this study was to investigate the effects of the plastic heel cup on the microchamber and macrochamber layers of the heel pad by comparing the stiffness (in terms of the shear wave speed) and thickness of these two layers with and without a plastic heel cup during static standing. Fifteen patients with unilateral plantar fasciitis were recruited. The shear wave speed and thickness of the microchamber and microchamber layers of each symptomatic heel pad during standing measured by ultrasound shear wave elastography were compared between conditions with and without a plastic heel cup. It was found that a plastic heel cup reduced the shear wave speed of the microchamber layer to 55.5% and increased its thickness to 137.5% compared with the condition without a plastic heel cup. For the microchamber layer, the shear wave speed was reduced to 89.7%, and thickness was increased to 113.6% compared with the condition without a plastic heel cup. The findings demonstrate that a plastic heel cup can help to reduce the stiffness and increase the thickness for both layers of the heel pad during standing, suggesting that the mechanism of a plastic heel cup, and its resulting biomechanical effect, is to reduce the internal stress of the heel pad by increasing its thickness through confinement.

A versatile method for dorsal-approach plantar plate repair using standard operative instruments.

BACKGROUND: The plantar plate is an important static stabilizer of the lesser metatarsophalangeal joints, and disruptions of the plantar plate can lead to significant instability and lesser toe deformities. In recent years, direct plantar plate repair has been proposed. Although direct repair via a dorsal approach is attractive, a torn plantar plate is small and difficult to access using regular instruments in a restricted operative field. METHODS: In this report, a unique method for plantar plate repairs was used to repair various configurations of plantar plate tears with standard operative instruments that are available in most operating rooms. RESULTS: Using this method, 10 patients underwent plantar plate repairs, and the mean follow-up period was 24 (range, 14-38) months. The mean visual analog scale score for pain preoperatively was 4.1 (range, 0-6) and decreased to 0.6 (range, 0-3) at last follow-up. Postoperatively, the mean visual analog scale score for satisfaction was 9.6 (range, 8-10) and the mean American Orthopedic Foot and Ankle Society forefoot score was 88.8 (range, 75-100). CONCLUSIONS: Our study proposes an inexpensive and versatile method for plantar plate repair via a dorsal approach that uses standard operative instruments. TRIAL REGISTRATION: ClinicalTrials.gov , NCT04949685 . July 2, 2021 - Retrospectively registered, LEVEL OF CLINICAL EVIDENCE: 4.

A Modified Extra-articular Lateral Column Lengthening Procedure for Adult Acquired Flatfoot Deformity.

BACKGROUND: Lateral column lengthening (LCL), originally described by Evans, is an established procedure to correct stage II adult acquired flatfoot deformity (AAFD). However, the relative position between the facets is violated, and other problems may include nonunion, malunion, and calcaneocuboid (CC) joint subluxation. Herein, we report a modified extra-articular technique of LCL with hockey-stick osteotomy, which preserves the subtalar joint as a whole, increases bony apposition to enhance healing ability, and preserves the insertion of the calcaneofibular ligament to stabilize the posterior fragment to promote adduction of the forefoot. METHODS: We retrospectively recruited 24 patients (26 feet) with stage II AAFD who underwent extra-articular LCL. The mean age was 55.7 ± 15.7 years, and the mean follow-up period was 33.4 ± 12.1 months. Associated procedures of spring ligament repair/reconstruction and posterior tibial tendon plication or flexor digitorum longus transfer were routinely performed and may also include a Cotton osteotomy, heel cord lengthening, or hallux valgus correction. Clinical and radiographic outcomes at the final follow-up were compared with the preoperative assessments. RESULTS: All patients achieved calcaneus union within 3 months of operation. The VAS pain score improved from 5.3 ± 0.75 preoperatively to 1.2 ± 0.79 at the final follow-up (P < .001), and the AOFAS Ankle-Hindfoot Scale from 63.5 ± 8.5 to 85.8 ± 4.8 points (P < .001). The radiographic measurements significantly improved in terms of the preoperative vs final angles of 8.9 ± 5.3 vs 15.2 ± 3.6 degrees for calcaneal pitch (P < .001), 20.5 ± 9.2 vs 4.9 ± 4.8 degrees for Meary angle (P < .001), 46.5 ± 5.2 vs 41.9 ± 3.2 degrees for lateral talocalcaneal angle (P < .001), 23.9 ± 8.5 vs 3.9 ± 3.1 degrees for talonavicular coverage angle (P < .001), and 18.2 ± 9.2 vs 7.3 ± 5.0 degrees for talus-first metatarsal angle (P = .002). The CC joint subluxation percentage was 7.0% ± 5.4% preoperatively compared with 8.5% ± 2.4% at the final follow-up (P = .101). No case showed progression of CC joint arthritis or CC joint subluxation (>15% CC joint subluxation percentage). One case showed transient sural nerve territory paresthesia, and 1 had pin tract infection. Three cases had lateral foot pain, which could be relieved by custom insoles. CONCLUSION: Modified extra-articular LCL as part of AAFD correction is a feasible alternative technique without subtalar joint invasion and may be associated with less CC joint subluxation compared with the Evans osteotomy. LEVEL OF EVIDENCE: Level IV, retrospective case series.

Ultrasound-Guided Minimally Invasive Surgical Resection of Retrocalcaneal Bursitis: A Preliminary Comparison With Traditional Open Surgery.

Posterior heel pain is a common complaint that is often caused by overuse injuries. In such cases, the retrocalcaneal bursa is compressed and chafed repeatedly, leading to local inflammation. Sonography is a popular imaging tool used to study the pathology of soft tissues, and it can be used to assist in diagnosing bursitis because of its accuracy. Herein, we report an innovative method to treat retrocalcaneal bursitis under ultrasound guidance. Ten patients with posterior heel pain for >6 months who failed conservative treatment received this ultrasound-guided minimally invasive surgery. An endoscopic puncher and burr were inserted under ultrasound guidance via a stabbing wound, and the swollen retrocalcaneal bursa and bony prominence were resected. The patients were able to ambulate and undergo a rehabilitation program 2 weeks postoperatively. In the patients who underwent this ultrasound-guided minimally invasive surgery, both the average surgical time and average hospital stay were shorter than in those (n = 12) who underwent open surgery. In outcome rating assessment, the American Orthopaedic Foot & Ankle Society (AOFAS) pain score and total AOFAS ankle-hindfoot score were improved in the ultrasound-guided minimally invasive surgery group compared to the open surgery group at 2 months postoperatively. Other advantages included lesser wound pain, shorter hospital stay, faster recovery time, and minimal blood loss. Accordingly, ultrasound-guided surgery appears to be a good option for the treatment of retrocalcaneal bursitis.

Asymmetric Thickness of Oblique Capitis Inferior and Cervical Kinesthesia in Patients With Unilateral Cervicogenic Headache.

OBJECTIVE: The purpose of this study was to compare the thickness of the oblique cervical inferior (OCI) and the error of the head reposition test between the painful and nonpainful sides of patients with cervicogenic headache (CeH) and between the patients and the asymptomatic group. METHODS: Thirteen patients (24.5 ± 4.8 years) and 14 asymptomatic participants (23.9 ± 2.7 years) were included. The head reposition test was recorded by a 3-dimensional motion analysis system. The thickness of the OCI was recorded by ultrasonography. The measured outcomes were compared between the painful and nonpainful sides and with the asymptomatic participants. RESULTS: The thickness of the OCI in the rest condition on the painful side (9.92 ± 2.31 mm) was smaller than that of the nonpainful side (10.56 ± 2.24 mm). The constant error of the head-to-target test toward the nonpainful side was smaller in the patients with CeH (-1.6 ± 4.3°) than in the asymptomatic group (3.3 ± 3.7°, P = 0.005). CONCLUSION: Asymmetric OCI and cervical proprioception were demonstrated in patients with CeH.

Spatial-dependent mechanical properties of the heel pad by shear wave elastography.

The heel pad plays an important role in gait, and its biomechanical behavior and functionality are determined by its specialized architecture and mechanical properties. The purpose of this study was to apply supersonic shear wave elastography, an ultrasound-based noninvasive modality that can quantitatively estimate the shear stiffness of the tissue, to investigate the spatial-dependent mechanical properties of the heel pad. Measurements were conducted in 40 heel pads of 20 normal participants aged between 20 and 30 years by shear wave elastography. The continuous change in local shear stiffness of the heel pad along the depth direction of the heel pad was measured. The result showed that the mechanical properties of the heel pad were highly heterogeneous but followed a simple and specific pattern that local heel pad shear stiffness was highest beneath the plantar skin and decreased continuously with increasing depth. This finding provides a better understanding of the heel pad biomechanics and basis for further investigation of the heterogeneous properties of the heel pad.

Mechanical deformation of posterior thoracolumbar fascia after myofascial release in healthy men: A study of dynamic ultrasound imaging.

BACKGROUND: Myofascial release (MR) on the posterior thoracolumbar fascia (PLF) is one of the manual techniques aim to restore the normal length and tension of restricted fasciae and muscles. OBJECTIVES: The present study aimed to quantify the immediate effects of MR on fascial properties of the PLF in healthy men. DESIGN: Cross-sectional study. METHOD: Participants (N = 10, aged 22.8 ± 2.0 years) performed a press-down to maximal voluntary contraction (MVC) in the prone position. Deformation of the PLF was measured using an ultrasonographic apparatus. Force output was simultaneously measured. The stiffness index and hysteresis index were then represented by the slope of the loading curve, and the percentage of the area within the loading-unloading curve. One-way ANCOVA was used to compare differences in the stiffness index or hysteresis index of the PLF before and after MR. Two-way repeated ANOVA was used to compare deformation of the PLF or force output after MR. RESULTS: The primary findings included a decrease (before: 24.1 ± 8.3 vs. after: 18.9 ± 5.3 N/mm; mean difference, -5.2 ± 4.9 N/mm, p = 0.002 < 0.05) in the stiffness index of the PLF and a greater difference in deformation of the PLF between 50% and 100% MVC (before: Def50% = 6.5 ± 1.8 mm and Def100% = 9.8 ± 1.9 mm vs. after: Def50% = 6.4 ± 2.5 mm and Def100% = 10.2 ± 2.4 mm; p = 0.037 < 0.05, power = 58.5%). CONCLUSION: After MR, stiffness of the PLF decreased in healthy men.

An Artifact in Supersonic Shear Wave Elastography.

Supersonic shear wave elastography is a novel ultrasound technology that allows objective evaluation of soft tissue stiffness. The purpose of this study is to report an artifact in supersonic shear wave elastography that may strongly affect the accuracy and quality of the measurement of soft tissue stiffness, and to step-by-step describe how the artifact was found and how it was verified by a series of experiments under different conditions. There were a total of three longitudinal band-like artifacts, 1.3 cm apart from each other on the entire image along the length of the SuperLinear SL15-4 transducer surface, with the middle one at the center of the image. When using supersonic shear wave elastography, users should be keenly aware of the possible occurrence of the artifact and avoid it by choosing the quantification measurement regions of interest (ROIs) away from the artifact regions.

Increased sliding of transverse abdominis during contraction after myofascial release in patients with chronic low back pain.

PURPOSE: Recent evidence suggested the significance of integrity of the tension balance of the muscle-fascia corset system in spinal stability, particularly the posterior musculofascial junction which is adjacent to dorsal located paraspinal muscles joining each other at lateral raphe (LR). The purpose of this study was to compare the contraction of the transversus abdominis (TrA) at both anterior and posterior musculofascial muscle-fascia junctions in patients with low back pain (LBP) and asymptomatic participants before and immediately after a sustained manual pressure to LR. METHODS: The present observational cohort study used a single-instance, test-retest design. The outcome variables included the resting thickness (Tr), the thickness during contraction (Tc), change in thickness (ΔT), sliding of musculofascial junction (ΔX), muscle length at rest (L) and displacement pattern (ΔD) of the TrA using ultrasonography. Vertical tolerable pressure at the LR was applied manual for 1 min. Tr, Tc, ΔT, and ΔX were analyzed by three-way ANOVA (musculofascial junction sites*group* pre-post manual release). ΔL and ΔD were analyzed by two-way ANOVA (group* pre-post manual release). RESULTS: Participants with LBP revealed less Tc, ΔT and ΔX at both sites (p < 0.005). After myofascial release, LBP group demonstrated a positive ΔD of the musculofascial junctions at both end (p < 0.001). Nevertheless, both groups increased the ΔT and ΔX at both sites (p < 0.001 and 0.001, respectively). CONCLUSION: The result indicated immediately effect of sustained manual pressure on musculofascial junction of TrA and supported the concept that the possible imbalanced tension of the myofascia corset of TrA in patients with LBP.

Heel Pad Stiffness in Plantar Heel Pain by Shear Wave Elastography.

The goal of the study was to evaluate the reliability of supersonic shear wave elastography in measuring heel pad stiffness and the change in heel pad stiffness in patients with plantar heel pain. In the reliability test involving 12 normal participants, each heel pad was tested six times in succession, and adequate reliability was reflected in the intraclass correlation coefficients (0.95, 0.93 and 0.96 for the microchambers, macrochambers and bulk heel pad, respectively). In the clinical assessment involving 20 normal participants and 16 unilateral plantar heel pain patients, diseased heel pads (86.8 ± 22.9, 36.8 ± 7.7 and 46.6 ± 10.9 kPa for the microchambers, macrochambers and bulk heel pad, respectively) were significantly stiffer than unaffected heel pads (66.8 ± 14.1, 25.2 ± 5.7, 34.2 ± 6.6 kPa) and those of normal participants (60.9 ± 11.4, 26.3 ± 6.1, 31.8 ± 6.3 kPa), suggesting that the heel pad with plantar heel pain was associated with loss of elasticity.

Modeling and Analysis of the Viscoelastic Response of the Ankle Ligament Complex in Inversion Ankle Sprain.

Since inversion ankle sprain (IAS) damages ankle ligaments and induces changes in their viscoelastic properties, evaluating these properties may provide an approach to assess injury. The study purposes were to investigate how the viscoelastic properties of the ankle ligament complex can be used to quantitatively assess IAS, and to investigate the usefulness of the stretched exponential function to analyze the relaxation behavior of the ankle ligament complex. Fifteen participants with unilateral IAS and 15 controls were included. The relaxation behavior of each ankle was measured by an instrumented anterior drawer test, and was then curvefitted by the stretched exponential function. By a modeling approach, both parameters of the function were found to be associated with the viscous response. Statistical analysis was performed to determine differences in these two parameters between sprained and uninjured ankles. It was found that sprained ankles exhibited significantly lower viscous response than uninjured ankles. No significant difference was found among uninjured ankles. In conclusion, by using the viscoelastic properties, sprained ankles were successfully differentiated from uninjured ankles. In clinical application, this method could be a diagnostic tool for quantitative assessment of IAS injury. The stretched exponential function was a useful model to analyze the relaxation behavior.

Relationship between viscosity of the ankle joint complex and functional ankle instability for inversion ankle sprain patients.

OBJECTIVES: Measurement of viscosity of the ankle joint complex is a novel method to assess mechanical ankle instability. In order to further investigate the clinical significance of the method, this study intended to investigate the relationship between ankle viscosity and severity of functional ankle instability. DESIGN: Cross-sectional study. METHODS: 15 participants with unilateral inversion ankle sprain and 15 controls were recruited. Their ankles were further classified into stable and unstable ankles. Ankle viscosity was measured by an instrumental anterior drawer test. Severity of functional ankle instability was measured by the Cumberland Ankle Instability Tool. Unstable ankles were compared with stable ankles. Injured ankles were compared with uninjured ankles of both groups. The spearman's rank correlation coefficient was applied to determine the relationship between ankle viscosity and severity of functional ankle instability in unstable ankles. RESULTS: There was a moderate relationship between ankle viscosity and severity of functional ankle instability (r=-0.64, p<0.0001). Unstable ankles exhibited significantly lower viscosity (p<0.005) and more severe functional ankle instability (p<0.0001) than stable ankles. Injured ankles exhibited significantly lower viscosity and more severe functional ankle instability than uninjured ankles (p<0.0001). CONCLUSIONS: There was a moderate relationship between ankle viscosity and severity of functional ankle instability. This finding suggested that, severity of functional ankle instability may be partially attributed to mechanical insufficiencies such as the degenerative changes in ankle viscosity following the inversion ankle sprain. In clinical application, measurement of ankle viscosity could be a useful tool to evaluate severity of chronic ankle instability.

Quantitative evaluation of the viscoelastic properties of the ankle joint complex in patients suffering from ankle sprain by the anterior drawer test.

PURPOSE: Biological tissues such as ligaments exhibit viscoelastic behaviours. Injury to the ligament may induce changes of these viscoelastic properties, and these changes could serve as biomarkers to detect the injury. In the present study, a novel instrument was developed to non-invasive quantify the viscoelastic properties of the ankle in vivo by the anterior drawer test. The purpose of the study was to investigate the reliability of the instrument and to compare the viscoelastic properties of the ankle between patients suffering from ankle sprain and controls. METHODS: Eight patients and eight controls participated in the present study. The reliability test was performed on three randomly chosen subjects. In patient and control test, both ankles of each subject were tested to evaluate the viscoelastic properties of the ankle. The viscosity index was defined for quantitatively evaluating the viscosity of the ankle. Greater viscosity index was associated with lower viscosity. Injured and uninjured ankles of patient and both ankles of controls were compared. RESULTS: The instrument exhibited excellent test-retest reliability (r > 0.9). Injured ankles exhibited significantly less viscosity than uninjured ankles, since injured ankles of patients had significantly higher viscosity index (8,148 ± 5,266) compared with uninjured ankles of patients (948 ± 617; p = 0.008) and controls (1,326 ± 613; p < 0.001). CONCLUSIONS: The study revealed that the viscoelastic properties of the ankle can serve as sensitive and useful clinical biomarkers to differentiate between injured and uninjured ankles. The method may provide a clinical examination for objectively evaluating lateral ankle ligament injuries.

Ultrasound-guided minimally invasive surgery for achilles tendon rupture: preliminary results.

BACKGROUND: Many surgeons prefer surgical repair for Achilles tendon ruptures in an attempt to reduce the risk of rerupture. To minimize wound complications, the use of minimally invasive surgery has become more popular recently. In line with this, the use of ultrasound to guide Achilles tendon repair is reported in this study. METHODS: From March 2005 to January 2008, 23 patients with Achilles tendon rupture were repaired by the same surgeon. The ages of the patients ranged from 19 to 67 years old, with an average of 43 years old. The repair of the Achilles tendon was achieved through a stab wound under the guidance of ultrasonography. A control group consisted of 25 patients who received traditional open Achilles tendon repair. RESULTS: The average operation time was 52 minutes, and the average wound size was 1.1 cm. The short leg cast was removed 4 weeks after the surgery, and serial casting was used for another 3 to 4 weeks. The postoperative AOFAS ankle-hindfoot scores were 98.7 in the experimental group, 96.5 in the control group with no significant difference. The rates of local infection, stiffness of the ankle, pain of the scar and sural nerve injury were better in the experimental group than in the control group with significant difference. CONCLUSIONS: Ultrasound-guided surgery was a good choice due to its availability and real-time soft tissue visualization. It can further minimize the size of the surgical wound. Our method has the potential to achieve reliable results.

Reliability and relationship between 2 measurements of transversus abdominis dimension taken during an abdominal drawing-in maneuver using a novel approach of ultrasound imaging.

STUDY DESIGN: Reliability study of clinical measurement. OBJECTIVES: The primary purpose was to develop a reliable method for measuring muscle length changes of the transversus abdominis (TrA) during contraction. The secondary purpose was to investigate the relationship between changes in thickness and length (as indicated by the lateral sliding of the anterior muscle-fascia junction) of the TrA muscle during an abdominal drawing-in maneuver. We also provide data on between-day reliability of change in thickness (ΔT) of the TrA. BACKGROUND: Ultrasound imaging measurements of TrA thickness at rest (Thr) and during maximal contraction (Thm) have been shown to be reliable. However, limited data exist on quantifying changes in TrA length (as indicated by the lateral sliding of the muscle-fascia junction [Δx]) and ΔT during contraction. METHODS: Eighteen healthy adults (mean ± SD age, 22.6 ± 2.5 years) participated in this study. Brightness mode ultrasound images of the TrA were collected at rest and during an abdominal drawing-in maneuver. Subjects were examined by the same examiner twice within a 48-hour period. ΔT, ΔT/Thr, Thr, Thm, and Δx of the TrA were calculated. Medial-lateral movement of the transducer during measurement was corrected through a custom-written program that used an internal marker created by an echo-absorptive thread attached to the skin. Intraclass correlation coefficients (ICC3,1), within-subject coefficient of variance, and standard error of measurement were calculated. The relationship between ΔT and adjusted Δx of the TrA muscle was investigated. RESULTS: The ICC values for Thr, Thm, and ΔT of the TrA muscle were greater than 0.75, with the exception of the left ΔT (0.62) and left ΔT/Thr (0.49). After adjusting for medial-lateral motion of the transducer, the ICC values of adjusted Δx were above 0.75, and the within-subject coefficient of variance was below 10%. There was no significant correlation between ΔT and adjusted Δx of the TrA. CONCLUSION: Ultrasound imaging measurements of TrA thickness and length change were shown to be reliable using a novel method to control for medial-lateral transducer motion. Measuring different but unrelated dimensional changes in the TrA might provide further insight as to the function of the TrA.

Relationship between plantar pressure and soft tissue strain under metatarsal heads with different heel heights.

BACKGROUND: Metatarsalgia due to increased plantar pressure under the metatarsal head (MTH) is often seen with wearing high-heeled shoes. However, the concomitant soft tissue strain has not been well discussed. The objective of our study was to explore the standing plantar pressure and corresponding soft tissue strain under the metatarsal heads (MTHs) with different heel heights. MATERIALS AND METHODS: Twenty-one healthy subjects (10 male and 11 female) participated. The plantar pressure and soft-tissue thicknesses were measured simultaneously with a load cell and a 10-MHz linear-array ultrasound (US) transducer respectively. The changes in plantar pressure and soft tissue strain under the MTHs were analyzed for different heel heights. RESULTS: As hypothesized, plantar metatarsal pressure significantly increased and shifted to the first and second MTHs with increasing heel height from 2 cm to 4 cm (p < 0.05). However, the change in soft tissue strain under the medial forefoot became insignificant when the heel height was greater than 2 cm (p = 0.473 and 0.517). CONCLUSIONS: Increased heel height resulted in increasing medial forefoot loading pressure; however, the soft tissue exhibited stationary compressibility when the heel height was greater than 2 cm. CLINICAL RELEVANCE: Our finding provides an understanding of the biomechanical changes with wearing high-heeled shoes and suggests possible strategies to reducing discomfort and risk of injury, such as limiting heel height to no greater than 2 cm and using medial padding under MTHs.

Diabetic effects on microchambers and macrochambers tissue properties in human heel pads.

BACKGROUND: The study attempted to highlight the differences of mechanical properties in microchambers and macrochambers between patients with type 2 diabetes mellitus and age-matched healthy volunteers. METHODS: A total of 29 heels in 18 diabetic patients and 28 heels in 16 age-matched healthy participants were examined by a loading device consisting of a 10-MHz compact linear-array ultrasound transducer, a Plexiglas cylinder, and a load cell. Subjects in both groups were on average about 55 years old with a body mass index of approximately 25 kg/m(2). A stepping motor was used to progressively load the transducer on the tested heels at a velocity of 6mm/s from zero to the maximum stress of 78 kPa. Unloaded thickness, strain, and elastic modulus in microchambers, macrochambers and heel pads were measured. FINDINGS: Microchambers strain in diabetic patients was significantly greater than that in healthy subjects (0.291 (SD 0.14) vs. 0.104 (SD 0.057); P<0.001). Macrochambers strain in diabetic patients was significantly less than that in healthy subjects (0.355 (SD 0.098) vs. 0.450 (SD 0.092); P=0.001). Microchambers stiffness in diabetic patients was significantly less than that in healthy persons (393 (SD 371)kPa vs. 1140 (SD 931)kPa; P<0.001). Macrochambers stiffness in diabetic patients was significantly greater than that in healthy persons (239 (SD 77)kPa vs. 181 (SD 42)kPa; P=0.001). INTERPRETATION: Heel pad tissue properties are altered heterogeneously in people with diabetes. Increased macrochambers but decreased microchambers stiffness may cause diminished cushioning capacities in diabetic heels.

A novel method for measuring electromechanical delay of the vastus medialis obliquus and vastus lateralis.

Electromechanical delay (EMD) of the vastus medialis obliquus (VMO) and vastus lateralis (VL) is determined by measuring the interval between the time of onset of muscle activities and the time of onset of mechanical output. However, individual mechanical output of the VMO or the VL cannot be obtained with the conventional method because of the knee extension force as the mechanical output. Therefore, the objective of the present study was to develop a new method for measuring EMD of the VMO and VL individually. Twelve healthy volunteers participated in the experiment. The motor point of the target muscle was electrically stimulated to evoke a muscle twitch. Simultaneously, the electrical stimulation signal was transmitted to ultrasound apparatus via the electrocardiography input channel. The ultrasound apparatus was used to capture the patellar movement elicited by the muscle twitch. EMD was measured from the onset of the electrical stimulation to the onset of patellar movement. The results showed that the intraclass correlation coefficients for the reproducibility of the EMD measurements of the VMO and VL were greater than 0.8. The EMDs of the VMO and VL were 18.3 +/- 2.2 ms and 24.8 +/- 5.8 ms, respectively. This new method provides a more precise measurement of EMD in the VMO and VL than does the conventional method because of the use of patellar movement as the mechanical output.