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1.
Appl Ergon ; 98: 103587, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34547577

RESUMO

Anterior load carriage is common in occupational work and daily activities. Our primary purpose was to systematically review previous work concerning the biomechanics of walking with anterior load carriage. A secondary goal was to conduct a meta-analysis on common gait parameters relevant to front load carriage. An electronic database search yielded eight qualified articles. Meta-analyses were performed for four gait variables: stride length, heel contact velocity, required coefficient of friction, double support time. When possible, subgroup analyses by age were conducted. Results suggest that walking with front load carriage may shorten the stride length, particularly among young adults, but has small effects on the other three variables. Findings should be interpreted with caution given the limited number of studies included and small sample size per study. Future work investigating these four variables and others is needed to further our understanding of the impact of front load carriage on gait.


Assuntos
Marcha , Caminhada , Fenômenos Biomecânicos , Fricção , Humanos , Suporte de Carga , Adulto Jovem
2.
Swiss Dent J ; 131(11): 897-910, 2021 Nov 08.
Artigo em Alemão | MEDLINE | ID: mdl-34753282

RESUMO

Direct composite restorations are placed in the cavities in the posterior region using an incremental layering technique. Numerous different layering concepts are described in the literature. However, only those procedures that can be easily and reliably applied in routine clinical treatment have become established in daily practice. This article is intended to provide a clinically oriented overview of the most common layering procedures for the direct restoration of posterior defects with plastic composite materials.


Assuntos
Cárie Dentária , Restauração Dentária Permanente , Resinas Compostas , Humanos , Suporte de Carga
3.
Sensors (Basel) ; 21(21)2021 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-34770589

RESUMO

Mechanisms behind compromised balance control in people with transtibial amputation need to be further explored, as currently little is known specifically about postural control strategies in people with traumatic transtibial amputation (tTTA). The aim of this study is to assess automatic and voluntary postural control strategies in individuals with unilateral tTTA compared to those in control subjects and to define the effect of balance-related factors on these strategies. Automatic posture reactions and volitional motion toward given direction using standardized posturographic protocols (NeuroCom) of the Motor Control Test (MCT) and Limits of Stability (LOS) were assessed in eighteen participants with tTTA and eighteen age-matched controls. Compared to the controls, the participants with tTTA bore less weight on the prosthetic leg (p < 0.001) during the MCT and had reduced inclination toward the prosthetic leg (p < 0.001) within the LOS. In the tTTA group, the weight-bearing symmetry and the inclination toward the prosthetic leg (p < 0.05) was positively correlated with prosthesis use duration (p < 0.05). The current study indicates that decreased utilization of the prosthetic leg in tTTAs represents adaptive postural control strategy, but as prosthesis use duration increased, the engagement of the prosthetic leg improved.


Assuntos
Membros Artificiais , Equilíbrio Postural , Amputação , Humanos , Postura , Suporte de Carga
4.
Foot Ankle Clin ; 26(4): 685-704, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34752234

RESUMO

This article describes the 3 main surgical options for correction of congenital brachymetatarsia in childhood. The one-stage lengthening by lengthening osteotomy and lengthening with graft interposition are suitable for defects less than 10 mm. For the greater defects from 10 mm to more than 20 mm, gradual lengthening by callus distraction with an external or internal fixator is appropriate. Over the last years, callus distraction with an internal minifixator became commonly established because of the significantly improved aftercare with early full weight-bearing and high postoperative comfort for the child. All 3 surgical procedures are presented with comprehensive image material.


Assuntos
Deformidades Congênitas do Pé , Ossos do Metatarso , Osteogênese por Distração , Fixadores Externos , Humanos , Osteotomia , Suporte de Carga
5.
J Craniofac Surg ; 32(7): 2401-2405, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-34705386

RESUMO

PURPOSE: To critically examine reported data to compare patient outcomes between load-sharing and load-bearing plate fixation for edentulous mandibular fractures. MATERIALS AND METHODS: A systematic review and meta-analysis were designed to test the null hypothesis of no difference in postoperative outcomes between load-sharing and load-bearing plate fixation in atrophic, edentulous mandibular fractures. The PubMed, EMBASE, Cochrane Library, Elsevier text mining tool database, and clinicaltrials.gov trial registries were queried up until July 2016. The quality of evidence was determined using the Grading of Recommendations Assessment, Development, and Evaluation method. RESULTS: A total of 1212 studies were screened for inclusion of which we included 1 high-quality Cochrane review, 6 narrative reviews, and 21 publications of case reports and case series. Overall, the quality of evidence was low. No difference was found between load-bearing and load-sharing fixation in functional recovery, nonunion, or infection. An uncontrolled case series portrayed complete functional and morphological restoration in 96.9% of patients (83.2-99.5; 95% confidence interval) in load-bearing osteosynthesis while another demonstrated the same outcome in only 40.0% of patients (17.5-65.0; 95% confidence interval). CONCLUSIONS: The authors did not find a statistically significant difference between load-bearing and load-sharing plate fixation in edentulous atrophic mandibular fracture patients; although this finding may be influenced by type 2 statistical error. Surgeons should continue to use their best clinical judgment in deciding on treatment approach for these challenging fractures. Future studies with higher level evidence are necessary to guide optimal fracture management.


Assuntos
Fraturas Mandibulares , Boca Edêntula , Placas Ósseas , Fixação Interna de Fraturas , Humanos , Fraturas Mandibulares/cirurgia , Suporte de Carga
6.
BMC Musculoskelet Disord ; 22(1): 902, 2021 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-34696737

RESUMO

BACKGROUND: Diagnosing patellofemoral instability disorders correctly, weight-bearing MRI (WB-MRI) has become an option. Aiming for a best possible accuracy in displaying potentially underlying causes, the named MRI modalities were sporadically even investigated in different knee flexion angles. However, despite confirmed MRI-outcome-differences between WB-MRI and non-WB-MRI, none of the described MRI modalities have so far established themselves. Mainly this is due to an unfeasibility in daily clinical routine in regard to time and economic aspects. Thus, we intended to evaluate an additional but reduced patellofemoral MR-imaging solely in a relevant 20° of knee flexion under WB- and non-WB-MRI conditions. METHODS: Seventy-three subjects with and without patellofemoral instability were investigated under supine as well as under WB-MRI conditions in a 20° of knee flexion angle. Patellofemoral risk indices in the sagittal plane (Insall-Salvati-Index, Caton-Deschamps-Index, Patellotrochlear Index) and the axial plane (Patella tilt of Fulkerson and Sasaki) were detected and compared between the different MRI conditions. Significance, reliability and Cohen's effect size was calculated. RESULTS: Nearly all assessed indices showed significant differences between patients and controls in the different MRI positions. Comparing pairwise, all measured indices failed to show significant differences between the two MRI positions. However, patella tilt angles of the patient group showed an elevation from supine to WB-MRI (14.00 ± 7.54° to 15.97 ± 9.10° and 16.34 ± 7.84° to 18.54 ± 9.43°). Here, Cohen's d showed small to medium effects between supine and WB-MRI. CONCLUSION: In comparison to standard MRI in supine position, axial risk indices seem to be accentuated under WB-MRI and a knee flexion angle of 20°. In particular, symptomatic cases with inconspicuous conventional MRI imaging, additional MRI imaging only in the axial plane in a 20° of knee flexion could be beneficious and useful in clinical daily routine.


Assuntos
Articulação Patelofemoral , Humanos , Articulação do Joelho/diagnóstico por imagem , Imageamento por Ressonância Magnética , Patela , Articulação Patelofemoral/diagnóstico por imagem , Reprodutibilidade dos Testes , Suporte de Carga
7.
Mater Sci Eng C Mater Biol Appl ; 130: 112461, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34702536

RESUMO

Laser powder bed fusion (LPBF) additive manufacturing of pure tantalum and their graded lattice structures was systematically investigated, with emphasis on their microstructure evolution, phase formation, surface energy and biological properties in comparison with conventionally forged pure Ta. The LPBF fabricated Ta (LPBF-Ta) exhibited lower contact angles and higher surface energy than the forged-Ta which indicated the better wettability of the LPBF-Ta. The adhesion and proliferation of rat bone marrow stromal cells (rBMSCs) were also enhanced for the LPBF-Ta when compared to forged-Ta. Three different Ta graded gyroid lattice structures (i.e., uniform structure, Y-gradient structure, Z-gradient structure) were designed and fabricated using the same optimised LPBF parameters. Y-gradient structures exhibited the best plateau stress and compressive modulus among three different graded structures due to the maximum local volume fraction on the fracture plane. In fatigue response, Y-gradient outperformed the other two gyroid structures under varying stresses. In terms of cell culture response, the uniform structures performed the best biocompatibility due to its suitable pore size for cell adhesion and growth. This study provides new and in-depth insights into the LPBF additive manufacturing of pure Ta graded lattice structures with desired fatigue and biological properties for load-bearing orthopaedic applications.


Assuntos
Ortopedia , Tantálio , Animais , Teste de Materiais , Porosidade , Ratos , Suporte de Carga
8.
BMC Musculoskelet Disord ; 22(1): 878, 2021 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-34649545

RESUMO

BACKGROUND: Early weight-bearing is becoming increasingly common because it can positively affect the quality of life of patients. Therefore, the efficacy and safety of this conservative treatment should be assessed for different types of ankle fractures. The goal of this study was to compare early weight-bearing and non-weight-bearing in terms of effectiveness and safety in patients with pronation rotation type III ankle fractures treated nonsurgically. METHODS: A prospective multicenter cohort study was conducted over two years. Elderly patients with a nondisplaced pronation rotation type III ankle fracture were included. The main variables were the Barthel Index and SF-12 scores. The patients completed the questionnaires at six weeks, one year and two years. We also compared the complications associated with the two interventions. RESULTS: 30 patients were included in the weight-bearing group, while 32 patients were included in the non-weight-bearing (WB) group. The mean ages were 82.6 ± 2.6 years and 83.1 ± 2.6 years, respectively. Quality of life, measured with the SF-12 scale, increased significantly in both the short and long term in the WB group (53.5 ± 5.8 points vs 65.2 ± 4.4 points at 6 weeks and 70.1 ± 4.2 points vs. 80.9 ± 3.7 points at 2 years; p<0.001). The WB group also showed a higher quality of life, as measured by the Barthel Index (54.5 ± 5.2 points vs. 64.3 ± 4.0 points at 6 weeks and 71.0 ± 4.3 points vs. 80.7 ± 3.4 points at 2 years; p<0.001). CONCLUSIONS: Elderly patients with pronation rotation type III fractures could benefit from an early weight-bearing protocol in terms of quality of life and functionality.


Assuntos
Fraturas do Tornozelo , Idoso , Idoso de 80 Anos ou mais , Fraturas do Tornozelo/diagnóstico por imagem , Fraturas do Tornozelo/terapia , Estudos de Coortes , Fixação Interna de Fraturas , Humanos , Pronação , Estudos Prospectivos , Qualidade de Vida , Rotação , Resultado do Tratamento , Suporte de Carga
9.
J Mech Behav Biomed Mater ; 124: 104854, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34601435

RESUMO

Collagen fibrils are the main structural component of load-bearing tissues such as tendons, ligaments, skin, the cornea of the eye, and the heart. The D-band of collagen fibrils is an axial periodic density modulation that can be easily characterized by tissue-level X-ray scattering. During mechanical testing, D-band strain is often used as a proxy for fibril strain. However, this approach ignores the coupling between strain and molecular tilt. We examine the validity of this approximation using an elastomeric collagen fibril model that includes both the D-band and a molecular tilt field. In the low strain regime, we show that the D-band strain substantially underestimates fibril strain for strongly twisted collagen fibrils - such as fibrils from skin or corneal tissue.


Assuntos
Matriz Extracelular , Tendões , Colágeno , Elasticidade , Suporte de Carga
10.
Medicina (Kaunas) ; 57(9)2021 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-34577864

RESUMO

Diabetic foot ulcers (DFU) are a leading cause of the global disease burden. Most DFUs are caused, and prolonged, by high plantar tissue stress under the insensate foot of a person with peripheral neuropathy. Multiple different offloading treatments have been used to try to reduce high plantar tissue stress and heal DFUs, including bedrest, casting, offloading devices, footwear, and surgical procedures. The best offloading treatments are those that balance the benefits of maximizing reductions in high plantar tissue stress, whilst reducing the risks of poor satisfaction, high costs and potential adverse events outcomes. This review aimed to summarize the best available evidence on the effects of offloading treatments to heal people with DFUs, plus review their use in clinical practice, the common barriers and solutions to using these treatments, and discuss promising emerging solutions that may improve offloading treatments in future. Findings demonstrate that knee-high offloading devices, non-removable or removable knee-high devices worn for all weight-bearing activities, are the gold standard offloading treatments to heal most patients with DFU, as they are much more effective, and typically safer, quicker, and cheaper to use compared with other offloading treatments. The effectiveness of offloading treatments also seems to increase when increased offloading mechanical features are incorporated within treatments, including customized insoles, rocker-bottom soles, controlled ankle motion, and higher cast walls. However, in clinical practice these gold standard knee-high offloading devices have low rates of prescription by clinicians and low rates of acceptance or adherence by patients. The common barriers resulting in this low use seem to surround historical misperceptions that are mostly dispelled by contemporary evidence. Further, research is now urgently required to close the implementation gap between the high-quality of supporting evidence and the low use of knee-high devices in clinical practice to reduce the high global disease burden of DFU in future.


Assuntos
Diabetes Mellitus , Pé Diabético , Pé Diabético/terapia , , Humanos , Articulação do Joelho , Suporte de Carga , Cicatrização
11.
Res Sports Med ; 29(6): 586-592, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34477036

RESUMO

This study examined the biomechanics of the lower limbs during four typical Tai Chi (TC) movements: wave hand in cloud, leaning fly side, repulse monkey, and brush knee and twist step, in order to provide biomechanical evidence-based recommendations for patients with knee osteoarthritis (OA) practicing TC. Joint angles and joint moments of the hip, knee, and ankle in frontal and sagittal plane as well as ground reaction forces were examined while performing TC and regular walking in an experienced 38 years old TC master. The results showed that relative to walking, the four TC movements are characterized by a wide motion range of lower limbs, slow increase in joint loading, and strong muscle activity during performance. Therefore, these TC movements could be suitable for patients with knee OA to practice for improving the muscle strength of their lower limbs and functional ability.


Assuntos
Extremidade Inferior/fisiologia , Osteoartrite do Joelho/fisiopatologia , Osteoartrite do Joelho/reabilitação , Amplitude de Movimento Articular/fisiologia , Tai Ji/métodos , Caminhada/fisiologia , Suporte de Carga/fisiologia , Adulto , Fenômenos Biomecânicos , Humanos , Cinética , Masculino
12.
FASEB J ; 35(10): e21792, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34516688

RESUMO

The benefits of increased human lifespan depend upon duration of healthy, independent living; the healthspan. Bone-wasting disorders contribute significantly to loss of independence, frailty, and morbidity in older people. Therefore, there is an unmet need globally for lifestyle interventions to reduce the likelihood of bone fractures with age. Although many mechanisms are involved in disorders of bone loss, there is no single regulatory pathway and, therefore, there is no single treatment available to prevent their occurrence. Our aim in these studies was to determine whether fasting/feeding interventions alter the effect of mechanical loading on bone anabolic activities and increase bone mass. In young 17-week-old mice, 16-hour fasting period followed by reintroduction of food for 2 hours increased markedly the potency of mechanical loading, that mimics the effect of exercise, to induce new cortical bone formation. Consistent with this finding, fasting and re-feeding increased the response of bone to a loading stimulus that, alone, does not stimulate new bone formation in ad-lib fed mice. Older mice (20 months) experienced no potentiation of loading-induced bone formation with the same timing of feeding interventions. Interestingly, the pre-, prandial, and postprandial endocrine responses in older mice were different from those in young animals. The hormones that change in response to timing of feeding have osteogenic effects that interact with loading-mediated effects. Our findings indicate associations between timing of food ingestion and bone adaptation to loading. If translated to humans, such non-pharmacological lifestyle interventions may benefit skeletal health of humans throughout life-course and in older age.


Assuntos
Adaptação Fisiológica , Densidade Óssea , Comportamento Alimentar , Osteogênese , Estresse Mecânico , Animais , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Suporte de Carga
13.
Acta Biomed ; 92(4): e2021236, 2021 09 02.
Artigo em Inglês | MEDLINE | ID: mdl-34487095

RESUMO

BACKGROUND AND AIM OF THE WORK: The incidence of pelvic and acetabular fractures is increasing during the years, counting 37 pelvic fractures per 100000 people annually. No weight bearing or toe touch weight bearing are usually chosen in the initial management to allow fracture and ligamentous healing and avoid fracture displacement and fixation failure. On the other hand, early weight bearing may stimulate fracture healing and allow prompt functional recovery, faster return to work and recreational activities and reduce complications linked to late rehabilitation.  Aim of the study is to review the literature about weight bearing indications for pelvic and acetabular fractures to highlight clinical and biomechanical evidence supporting early weight bearing. METHODS: Two independent reviewers independently extracted studies on early weight bearing of pelvic and acetabular fractures. All selected studies were screened independently based on title and abstract. Then the full text of any article that either judged potentially eligible was acquired and reviewed again. Any disagreement was resolved by discussing the full text manuscripts. RESULTS: 44 studies including reviews, meta-analysis, clinical and biomechanical studies were selected. CONCLUSIONS: Despite biomechanical data, few clinical evidences can be found to support early weight bearing in pelvic and especially acetabular fractures treatment. The promising results of some clinical experiences, however, should direct further studies to clearly define the indications and limits of early weight bearing in these injuries. Recognizing intrinsic lesion stability and bone and fixation technique quality, together with patient age and compliance, should be the mainstay for post-operative management choice.


Assuntos
Fraturas Ósseas , Ossos Pélvicos , Acetábulo/diagnóstico por imagem , Fixação Interna de Fraturas , Humanos , Suporte de Carga
14.
Bone Joint J ; 103-B(9): 1505-1513, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34465147

RESUMO

AIMS: Anterior cruciate ligament (ACL) rupture commonly leads to post-traumatic osteoarthritis, regardless of surgical reconstruction. This study uses standing MRI to investigate changes in contact area, contact centroid location, and tibiofemoral alignment between ACL-injured knees and healthy controls, to examine the effect of ACL reconstruction on these parameters. METHODS: An upright, open MRI was used to directly measure tibiofemoral contact area, centroid location, and alignment in 18 individuals with unilateral ACL rupture within the last five years. Eight participants had been treated nonoperatively and ten had ACL reconstruction performed within one year of injury. All participants were high-functioning and had returned to sport or recreational activities. Healthy contralateral knees served as controls. Participants were imaged in a standing posture with knees fully extended. RESULTS: Participants' mean age was 28.4 years (SD 7.3), the mean time since injury was 2.7 years (SD 1.6), and the mean International Knee Documentation Subjective Knee Form score was 84.4 (SD 13.5). ACL injury was associated with a 10% increase (p = 0.001) in contact area, controlling for compartment, sex, posture, age, body mass, and time since injury. ACL injury was associated with a 5.2% more posteriorly translated medial centroid (p = 0.001), equivalent to a 2.6 mm posterior translation on a representative tibia with mean posteroanterior width of 49.4 mm. Relative to the femur, the tibiae of ACL ruptured knees were 2.3 mm more anteriorly translated (p = 0.003) and 2.6° less externally rotated (p = 0.010) than healthy controls. ACL reconstruction was not associated with an improvement in any measure. CONCLUSION: ACL rupture was associated with an increased contact area, posteriorly translated medial centroid, anterior tibial translation, and reduced tibial external rotation in full extension. These changes were present 2.7 years post-injury regardless of ACL reconstruction status. Cite this article: Bone Joint J 2021;103-B(9):1505-1513.


Assuntos
Lesões do Ligamento Cruzado Anterior/diagnóstico por imagem , Lesões do Ligamento Cruzado Anterior/terapia , Fêmur/diagnóstico por imagem , Imageamento por Ressonância Magnética/métodos , Tíbia/diagnóstico por imagem , Adulto , Reconstrução do Ligamento Cruzado Anterior , Fenômenos Biomecânicos , Feminino , Fêmur/cirurgia , Humanos , Masculino , Rotação , Posição Ortostática , Tíbia/cirurgia , Suporte de Carga
15.
Biomater Sci ; 9(20): 6753-6762, 2021 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-34498620

RESUMO

Fast advances in soft robotics and tissue engineering demand for new soft materials whose mechanical properties can be interchangeably and locally varied, thereby enabling, for example, the design of soft joints within an integral material. Inspired by nature, we introduce a competitive ligand-mediated approach to selectively and interchangeably reinforce metal-coordinated hydrogels. This is achieved by reinforcing carboxylate-containing hydrogels with Fe3+ ions. Key to achieving a homogeneous, predictable reinforcement of the hydrogels is the presence of weak complexation agents that delay the formation of metal-complexes within the hydrogels, thereby allowing a homogeneous distribution of the metal ions. The resulting metal-reinforced hydrogels show a compressive modulus of up to 2.5 MPa, while being able to withstand pressures as high as 0.6 MPa without appreciable damage. Competitive ligand exchanges offer an additional advantage: they enable non-linear compositional changes that, for example, allow the formation of joints within these hydrogels. These features open up new possibilities to extend the field of use of metal reinforced hydrogels to load-bearing applications that are omnipresent for example in soft robots and actuators.


Assuntos
Hidrogéis , Engenharia Tecidual , Ligantes , Suporte de Carga
16.
J Am Acad Orthop Surg ; 29(23): 985-997, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34478409

RESUMO

Up to 10% of ankle sprains are considered "high ankle" sprains with associated syndesmotic injury. Initial diagnosis of syndesmotic injury is based on physical examination, but further evaluation of the distal tibiofibular joint in the sagittal, coronal, and rotational planes is necessary to determine instability. Imaging modalities including weight-bearing CT and ultrasonography allow a physiologic and dynamic assessment of the syndesmosis. These modalities in turn provide the clinician useful information in two and three dimensions to identify and consequently treat syndesmotic instability, especially when subtle. Because there is notable variability in the shape of the incisura between individuals, contralateral comparison with the uninjured ankle as an optimal internal control is advised. Once syndesmotic instability is identified, surgical treatment is recommended. Several fixation methods have been described, but the foremost aspect is to achieve an anatomic reduction. Identifying any associated injuries and characteristics of the syndesmotic instability will lead to the appropriate treatment that restores the anatomy and stability of the distal tibiofibular joint.


Assuntos
Traumatismos do Tornozelo , Instabilidade Articular , Traumatismos do Tornozelo/diagnóstico por imagem , Traumatismos do Tornozelo/cirurgia , Articulação do Tornozelo/diagnóstico por imagem , Articulação do Tornozelo/cirurgia , Artroscopia , Fixação Interna de Fraturas , Humanos , Instabilidade Articular/diagnóstico , Instabilidade Articular/cirurgia , Suporte de Carga
17.
Iowa Orthop J ; 41(1): 103-109, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34552411

RESUMO

Background: Malrotation of medial column bones of the foot has been advocated as an important factor in foot conditions such as hallux valgus and progressive collapsing foot deformity. Although stated as a deformity component, variances of normality in the general population are not completely understood. This study intended to describe the rotational profile of all medial column bones using weightbearing computed tomography (WBCT) images in a cohort of patients with different foot and ankle problems. Methods: In this retrospective study, 110 feet of 95 consecutive patients that received a WBCT for assessment of different foot and ankle pathologies were included. Measurements were performed by a blinded fellowship-trained orthopedic foot and ankle surgeon. Rotation of the navicular, medial cuneiform, proximal and distal first metatarsal as well as proximal phalanx of the first toe were recorded. Positive values were considered pronation and negative values were considered supination. Rotational profile of each bone/ segment was assessed by ANOVA and comparison between each segment was performed using Wilcoxon Each-Pair analysis. P-values of less than 0.05 were considered significant. Results: On average, a rotational positioning in pronation (internal rotation) was observed for all medial column bones. The navicular (43.2°, CI 41.1°-45.3°) and the proximal metatarsal (33.9°, CI 31.8°-36.0°) showed the highest mean rotation values. The medial cuneiform presented the lowest mean pronation (6.1°, CI 4.0°-8.3°). Comparison between each bone segment demonstrated statistically significant differences of rotational alignment for the different bones (p<0.0001), with the exception of the distal metatarsal and proximal phalanx, that had similar amounts of pronation. A zig-zag rotational pattern of alignment was observed from proximal to distal, with relative supination/pronation of adjacent medial column bones. Conclusion: The overall rotational profile of medial column bones was found to be in absolute pronation, most pronounced at the navicular and proximal first metatarsal, with significant differences in the amount of pronation when comparing most of the medial column bones. The presented data may be utilized as reference/ baseline values of medial column rotation, supporting future prospective, comparative and controlled studies.Level of Evidence: IV.


Assuntos
Hallux Valgus , Ossos do Metatarso , Hallux Valgus/diagnóstico por imagem , Hallux Valgus/cirurgia , Humanos , Ossos do Metatarso/diagnóstico por imagem , Estudos Retrospectivos , Tomografia Computadorizada por Raios X , Suporte de Carga
18.
Iowa Orthop J ; 41(1): 111-119, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34552412

RESUMO

Background: Weightbearing computed tomography (WBCT) is a reliable and precise modality for the measurement and analysis of bone position in the foot and ankle, as well as associated deformities. WBCT to assess three dimensional relationships among bones allowed the development of new measurements, as the Foot and Ankle Offset (FAO), which has high inter and intra-rater reliability. This study reports the University of Iowa's experience utilizing WBCT for the care of foot and ankle patients by describing its utility across different orthopedic diseases in improving diagnostic assessment, aiding surgical planning, and expanding the use for objective clinical follow-up. Methods: The medical records of consecutive patients with various foot and ankle disorders that underwent WBCT examination as part of the standard of care at a single institution between November 2014 and August 2020 were retrospectively reviewed. Patient factors, including body mass index (BMI), sex, and patient comorbidities were collected. 3D coordinates for calculation of FAO were harvested using the Multiplanar Reconstruction (MPR) views were calculated from the obtained exams. Descriptive statistics were performed with Shapiro-Wilk test and the Anderson-Darling tests. Results: 1175 feet and ankles (820 patients) had a WBCT performed over the studied 68 months. 53% of the subjects were male and 47% female. 588 of the acquisitions were from the right side (50.04%) and 587 from the left side (49.96%). Diabetes was present in 15.47% of, Rheumatic diagnoses in 4.52% and smoking habits in 44.10% of patients. Mean BMI of the sample was found to be 32.47 (32.03-32.90, 95% CI). The mean Foot and Ankle Offset (FAO) encountered in the study's population was 2.43 (2.05-2.82, 95% CI; min -30.8, max 37.65; median 2.39). Conclusion: This study contains the largest cohort of WBCTs with accompanied FAO measurements to date, which can aid with establishing a new baseline FAO measurement for multiple pathological conditions. Acquiring WBCTs resulted in a variety of more specific diagnoses for patient with foot and ankle complaints. The ability to utilize WBCT for presurgical planning, the capability to provide a 3D reconstruction of patient anatomy, and its use for assessment of advanced relational foot and ankle measurements, such as FAO, demonstrate how WBCT may serve as a remarkable utility in clinical practice and has become a standard of care in our practice at the University of Iowa.Level of Evidence: IV.


Assuntos
Tornozelo , Tomografia Computadorizada por Raios X , Feminino , Humanos , Iowa , Masculino , Reprodutibilidade dos Testes , Estudos Retrospectivos , Suporte de Carga
19.
Acta Biomater ; 135: 705-722, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34469790

RESUMO

Additive manufacturing (AM) has enabled the fabrication of biodegradable porous metals to satisfy the desired characteristics for orthopedic applications. The geometrical design on AM biodegradable metallic scaffolds has been found to offer a favorable opportunity to regulate their mechanical and degradation performance in previous studies, however mostly confined to static responses. In this study, we presented the effect of the geometrical design on the dynamic responses of AM Mg scaffolds for the first time. Three different types of porous structures, based on various unit cells (i.e., biomimetic, diamond, and sheet-based gyroid), were established and then subjected to selective laser melting (SLM) process using group-developed Mg-Nd-Zn-Zr alloy (JDBM) powders. The topology after dynamic electropolishing, dynamic compressive properties, and dynamic biodegradation behavior of the AM Mg scaffolds were comprehensively evaluated. It was found that dynamic electropolishing effectively removed the excessive adhered powders on the surfaces and resulted in similar geometrical deviations amongst the AM Mg scaffolds, independent of their porous structures. The geometrical design significantly affected the compressive fatigue properties of the AM Mg scaffolds, of which the sheeted-based gyroid structure demonstrated a superior fatigue endurance limit of 0.85 at 106 cycles. Furthermore, in vitro dynamic immersion behaviors of the AM Mg scaffolds revealed a decent dependence on local architectures, where the sheeted-based gyroid scaffold experienced the lowest structural loss with a relatively uniform degradation mode. The obtained results indicate that the geometrical design could provide a promising strategy to develop desirable bone substitutes for the treatment of critical-size load-bearing defects. STATEMENT OF SIGNIFICANCE: Additive manufacturing (AM) has provided unprecedented opportunities to fabricate geometrically complex biodegradable scaffolds where the topological design becomes a key determinant on comprehensive performance. In this paper, we fabricate 3 AM biodegradable Mg scaffolds (i.e., biomimetic, diamond, and sheet-based gyroid) and report the effect of the geometrical design on the dynamic responses of AM Mg scaffolds for the first time. The results revealed that the sheeted-based gyroid scaffold exhibited the best combination of superior compressive fatigue properties and relatively uniform dynamic biodegradation mode, suggesting that the regulation of the porous structures could be an effective approach for the optimization of AM Mg scaffolds as to satisfy clinical requirements in orthopedic applications.


Assuntos
Materiais Biocompatíveis , Substitutos Ósseos , Metais , Porosidade , Tecidos Suporte , Suporte de Carga
20.
Acta Biomater ; 135: 425-440, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34481053

RESUMO

The leaflets of the atrioventricular heart valves (AHVs) regulate the one-directional flow of blood through a coordination of the extracellular matrix components, including the collagen fibers, elastin, and glycosaminoglycans. Dysfunction of the AHVs, such as those caused by unfavorable microstructural remodeling, lead to valvular heart diseases and improper blood flow, which can ultimately cause heart failure. In order to better understand the mechanics and remodeling of the AHV leaflets and how therapeutics can inadvertently cause adverse microstructural changes, a systematic characterization of the role of each constituent in the biomechanical properties is appropriate. Previous studies have quantified the contributions of the individual microstructural components to tissue-level behavior for the semilunar valve cusps, but not for the AHV leaflets. In this study, for the first time, we quantify the relationships between microstructure and mechanics of the AHV leaflet using a three-step experimental procedure: (i) biaxial tension and stress relaxation testing of control (untreated) porcine AHV anterior leaflet specimens; (ii) enzyme treatment to remove a portion of either the collagen or elastin constituent; and (iii) biaxial tensile and stress relaxation testing of the constituent-removed (treated) specimens. We have observed that the removal of ∼100% elastin resulted in a ∼10% decrease in the tissue extensibility with biaxial tension and a ∼10% increase in the overall stress reduction with stress relaxation. In contrast, removal of 46% of the collagen content insignificantly affected tissue extensibility with biaxial tension and significantly increased stress decay (10%) with stress relaxation. These findings provide an insight into the microstructure-mechanics relationship of the AHVs and will be beneficial for future developments and refinements of microstructurally informed constitutive models for the simulation of diseased and surgically intervened AHV function. STATEMENT OF SIGNIFICANCE: This study presents, for the first time, a thorough mechanical characterization of the atrioventricular heart valve leaflets before and after enzymatic removal of elastin and collagen. We found that the biaxial tensile properties of elastin-deficient tissues and collagen-deficient are stiffer. The fact of elastin supporting low-stress valve function and collagen as the main load-bearing component was evident in a decrease in the low-tension modulus for elastin-deficient tissues and in the high-tension modulus for collagen-deficient tissues. Our quantification and experimental technique could be useful in predicting the disease-related changes in heart valve mechanics. The information obtained from this work is valuable for refining the constitutive models that describe the essential microstructure-mechanics relationship.


Assuntos
Valva Aórtica , Elastina , Animais , Fenômenos Biomecânicos , Colágeno , Estresse Mecânico , Suínos , Suporte de Carga
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