Achilles tendon ruptures have been linked with detrimental changes in muscle-tendon structure, which may help explain long-term functional deficits. However, the causal effects of muscle-tendon ...structure on joint function have not been tested in a controlled setting. Therefore, the purpose of this study was to test the implications of muscle-tendon unit parameters on simulated single-leg heel raise height. We hypothesized that muscle fiber length and resting ankle angle – a clinical surrogate measure of tendon slack length – would predict single-leg heel raise height more strongly than other parameters. To test this hypothesis, we developed a two-part simulation paradigm that recreated clinically relevant muscle-tendon scenarios and then tested these parameters on single-leg heel raise height. We found that longer muscle fibers had the greatest positive effect on single-leg heel raise height. However, tendon slack length, determined by simulating resting ankle angles in a secondary analysis, revealed a stronger negative correlation with heel raise height. Our findings support previous clinical observations that both muscle fascicle length and resting tendon length are important muscle-tendon parameters for patient function. In addition to minimizing tendon elongation following rupture, treatment plans should focus on preserving plantarflexor muscle structure to mitigate functional loses following Achilles tendon ruptures.
Parametrized motion planning algorithms have high degrees of universality and flexibility, as they are designed to work under a variety of external conditions, which are viewed as parameters and form ...part of the input of the underlying motion planning problem. In this paper, we analyze the parametrized motion planning problem for the motion of many distinct points in the plane, moving without collision and avoiding multiple distinct obstacles with a priori unknown positions. This complements our prior work Cohen et al.
3
(SIAM J. Appl. Algebra Geom.
5
, 229–249), where parametrized motion planning algorithms were introduced, and the obstacle-avoiding collision-free motion planning problem in three-dimensional space was fully investigated. The planar case requires different algebraic and topological tools than its spatial analog.
Background:
Hyperpronation of the first metatarsal in hallux valgus (HV) is poorly understood by conventional weightbearing radiography. We aimed to evaluate this parameter using weightbearing ...computed tomography (WBCT) and to understand its association with other standard measurements.
Methods:
Retrospective evaluation of WBCT and weightbearing radiographs (WBXRs) was performed for 20 patients with HV feet and 20 controls with no such deformity. Axial computed tomography images of both groups were compared for the first metatarsal pronation angle (alpha angle) and tibial sesamoid subluxation (TSS) grades. The HV angle (HVA), first-second intermetatarsal angle (IMA), first metatarsal-medial cuneiform angle (MMCA), Meary’s angle, and calcaneal pitch (CP) angle of the study and control groups were compared on both WBXR and the corresponding 2-dimensional images of WBCT. All measurements were independently performed by 1 musculoskeletal radiology fellow and 1 foot and ankle surgical fellow. Measurements were averaged and interobserver reliability was calculated.
Results:
The HV group demonstrated significantly higher values for TSS grade (P < .001) but not for alpha angle (P = .121) compared with controls. Likewise, significantly elevated HVA and IMA were noted in the HV group on both imaging modalities, while no such differences were observed for the CP angle. Higher MMCA and Meary’s angle in the HV group were evident only on WBXR (MMCA, P = .039; Meary’s, P = .009) but not on WBCT (MMCA, P = .183; Meary’s, P = .171).
Among all, the receiver operating characteristic (ROC) curves demonstrated the greatest area under the curve (AUC) for HVA, followed by IMA. The alpha angle performed only just outside the range of chance (AUC, 0.65; 95% CI, 0.52-0.69). The Pearson’s correlations of the alpha angle, in the HV group, revealed a significant linear relationship with TSS grade and with HVA on WBXR, and only trended toward a weak linear relationship with IMA and with HVA on WBCT.
Conclusion:
The alpha angle, a measure of abnormal hyperpronation of the first metatarsal, was an independent factor that may coexist with other parameters in HV, but in isolation had limited diagnostic utility. “Abnormal” alpha angles were even observed in individuals without HV. Increases in IMA and MMCA were not necessarily associated with similar increases in alpha angle, despite moderate correlations with TSS grade and HVA on WBXR. Nevertheless, the WBCT was a useful method for assessing hyperpronation and guiding surgical management in individual cases.
Level of Evidence:
Level III, retrospective comparative study.
Background
The published outcomes of total ankle replacement (TAR) implants came from limited institutions creating observational bias. For broader perspective, we queried the Food and Drug ...Administration’s (FDA) Manufacturer and User Facility Device Experience (MAUDE) voluntary database to explore complications reported outside published literature.
Methods
The database was reviewed retrospectively between November 2011 and April 2019 using two product codes assigned to six TAR devices.
Results
Among 648 relevant reports available in the database, common complications were aseptic loosening (19.3%), infection (18.2%), and alignment/mechanical issues (16.5%). Others included instrument/instrumentation complications, impingement, polyethylene problems, fractures, avascular necrosis of talus (AVN), and packaging issues.
Conclusion
MAUDE database revealed various patterns of device-related malfunctions that have been under-reported in published data. Despite inconsistency in the available reports, it provided opportunities for improvements in quality control, device design, and ultimately patient safety. Database would be further strengthened by more robust reporting mechanism or mandatory reporting of device-related complications.
Background
Midfoot arthrodesis is a common procedure performed both for arthritis and correction of deformity. The optimal fixation for midfoot arthrodesis has not been established, though numerous ...studies have been investigating the fixation techniques of midfoot arthrodesis. The purpose of this study was to compare the union rate of midfoot arthrodesis using 4 different fixation strategies and investigate risk factors of nonunion following midfoot arthrodesis.
Methods
A retrospective chart review was performed for patients who underwent midfoot joint arthrodesis between January 2014 and May 2019. The rates of nonunion and postoperative complication were compared among 4 different fixation constructs: staple fixation, compression plate fixation, compression plate with lag screw fixation, and compression screw fixation. Predictors of nonunion following midfoot arthrodesis were investigated through a multivariable logistic regression analysis. A total of 95 patients (99 feet), including 240 midfoot joints were included in this study. The mean follow-up period was 78.4 weeks.
Results
Overall, bony union was achieved in 86 out of 99 (86.9%) patients, which included 218 out of 240 (90.8%) midfoot joints. A significant difference in the nonunion rate according to the type of fixation construct was found (P = .011); the compression screw alone fixation construct was noted to have a significantly higher nonunion rate than other fixation constructs. Diabetes mellitus (odds ratio OR = 0.179 95% CI: 0.059, 0.542), the type of fixation construct (compression screw alone; OR =1.789 95% CI: 1.071, 2.978), lack of adjuvant bone graft (OR = 2.803 95% CI: 1.081, 7.268, and postoperative nonanatomical alignment (OR = 3.937 95% CI: 1.278, 12.126) were identified as independent predictors of nonunion following midfoot arthrodesis.
Conclusion
The rate of nonunion following midfoot arthrodesis among 4 different commonly used fixation constructs was compared in this study. Risk factors of nonunion were investigated revealing that diabetes mellitus, compression screw fixation alone, lack of adjuvant bone graft, and postoperative nonanatomical alignment are independent predictors of nonunion following midfoot arthrodesis.
Levels of Evidence:
Level III: Comparative cohort study
Ecosystem services (the benefits to humans from ecosystems) are estimated globally at $125 trillion/year 1, 2. Similar assessments at national and regional scales show how these services support our ...lives 3. All valuations recognize the role of biodiversity, which continues to decrease around the world in maintaining these services 4, 5. The giant panda epitomizes the flagship species 6. Its unrivalled public appeal translates into support for conservation funding and policy, including a tax on foreign visitors to support its conservation 7. The Chinese government has established a panda reserve system, which today numbers 67 reserves 8, 9. The biodiversity of these reserves is among the highest in the temperate world 10, covering many of China’s endemic species 11. The panda is thus also an umbrella species 12—protecting panda habitat also protects other species. Despite the benefits derived from pandas, some journalists have suggested that it would be best to let the panda go extinct. With the recent downlisting of the panda from Endangered to Vulnerable, it is clear that society’s investment has started to pay off in terms of panda population recovery 13, 14. Here, we estimate the value of ecosystem services of the panda and its reserves at between US$2.6 and US$6.9 billion/year in 2010. Protecting the panda as an umbrella species and the habitat that supports it yields roughly 10–27 times the cost of maintaining the current reserves, potentially further motivating expansion of the reserves and other investments in natural capital in China.
•We estimate the value of ecosystem services of the giant panda and its nature reserves•Ecosystem services include provisioning, regulatory, and cultural services•The total value of ecosystem services was US$2.6–US$6.9 billion/year in 2010•Protecting the panda and its habitat yields 10–27 times the cost in conservation
Wei et al. estimate that the value of ecosystem services of the giant panda and its nature reserves was US$2.6–US$6.9 billion/year in 2010. Protecting the panda and its habitat yields roughly 10–27 times the cost of maintaining the current reserves, potentially motivating expansion of the reserves and other investments in natural capital in China.
We conduct a large-scale meta-analysis of heart failure genome-wide association studies (GWAS) consisting of over 90,000 heart failure cases and more than 1 million control individuals of European ...ancestry to uncover novel genetic determinants for heart failure. Using the GWAS results and blood protein quantitative loci, we perform Mendelian randomization and colocalization analyses on human proteins to provide putative causal evidence for the role of druggable proteins in the genesis of heart failure. We identify 39 genome-wide significant heart failure risk variants, of which 18 are previously unreported. Using a combination of Mendelian randomization proteomics and genetic cis-only colocalization analyses, we identify 10 additional putatively causal genes for heart failure. Findings from GWAS and Mendelian randomization-proteomics identify seven (CAMK2D, PRKD1, PRKD3, MAPK3, TNFSF12, APOC3 and NAE1) proteins as potential targets for interventions to be used in primary prevention of heart failure.
Background
There remains no clear consensus on patient satisfaction and functional outcomes following synthetic cartilage implant (SCI) implantation for hallux rigidus. The purpose of this study was ...to review our experience at a single academic institution using an SCI for treatment of hallux rigidus.
Methods
A retrospective review was performed of patients who underwent the SCI procedure for treatment of hallux rigidus between January 2017 and May 2019. Functional outcomes were evaluated using Patient-Reported Outcome Measures Informational System (PROMIS)-10 scores as well as a survey investigating patient satisfaction, self-reported clinical improvement, and changes in sporting ability. Patients were divided into satisfied versus unsatisfied subgroups, and between-group differences in preoperative variables and complications were reviewed. A total of 90 patients (96 implants) were included in this study. The mean follow-up time was 26.4 months.
Results
In all, 81.2% of patients reported that their foot was “much improved” (55.2%) or “improved” (26.0%) since undergoing the SCI procedure, whereas a slightly lower percentage, 74.0%, stated that they were “extremely satisfied” (41.7%) or “satisfied” (32.3%) at final follow-up. Patients were able to tolerate higher impact sporting activities after the procedure, and 75.0% of patients stated they would have the same surgery again. PROMIS-10 T-scores averaged 54.2 points for physical health and 57.4 points for mental health. Only 2.1% of patients required conversion to arthrodesis. Significant differences between the satisfied versus unsatisfied subgroups were found in preoperative corticosteroid injection use (21.1% vs 41.1%, respectively; P = .029) and preoperative VAS pain score (8.2 vs 7.1, respectively; P = .036).
Conclusion
The SCI procedure can be a viable option for treating hallux rigidus with high satisfaction overall, increased sport activity levels, and a very low revision rate. However, maximizing patient satisfaction may require more careful consideration of preoperative prognosticators and extensive patient counseling to ensure realistic expectations for recovery time and individual outcome.
Level of Evidence:
Level IV: Retrospective case series
PDF
