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Regeneration (Oxford, England) Aug 2015A variety of digit and limb repair and reconstruction methods have been used in different clinical settings, but regeneration remains an item on every plastic surgeon's... (Review)
Review
A variety of digit and limb repair and reconstruction methods have been used in different clinical settings, but regeneration remains an item on every plastic surgeon's "wish list." Although surgical salvage techniques are continually being improved, unreplantable digits and limbs are still abundant. We comprehensively review the structural and functional salvage methods in clinical practice, from the peeling injuries of small distal fingertips to multisegmented amputated limbs, and the developmental and tissue engineering approaches for regenerating human digits and limbs in the laboratory. Although surgical techniques have forged ahead, there are still situations in which digits and limbs are unreplantable. Advances in the field are delineated, and the regeneration processes of salamander limbs, lizard tails, and mouse digits and each component of tissue engineering approaches for digit- and limb-building are discussed. Although the current technology is promising, there are many challenges in human digit and limb regeneration. We hope this review inspires research on the critical gap between clinical and basic science, and leads to more sophisticated digit and limb loss rescue and regeneration innovations.
PubMed: 27499873
DOI: 10.1002/reg2.41 -
The International Journal of... 2018The distal part of the tetrapod limb, the autopod, is characterized by the presence of digits. The digits display a wide diversity of shapes and number reflecting... (Review)
Review
The distal part of the tetrapod limb, the autopod, is characterized by the presence of digits. The digits display a wide diversity of shapes and number reflecting selection pressure for functional adaptation. Despite extensive study, the different aspects of digit patterning, as well as the factors and mechanisms involved are not completely understood. Here, we review the evidence implicating Hox proteins in digit patterning and the interaction between Hox genes and the Sonic hedgehog/Gli3 pathway, the other major regulator of digit number and identity. Currently, it is well accepted that a self-organizing Turing-type mechanism underlies digit patterning, this being understood as the establishment of an iterative arrangement of digit/interdigit in the hand plate. We also discuss the involvement of 5' Hox genes in regulating digit spacing in the digital plate and therefore the number of digits formed in this self-organizing system.
Topics: Animals; Body Patterning; Extremities; Gene Expression Regulation, Developmental; Genes, Homeobox; Hedgehog Proteins; Signal Transduction
PubMed: 30604849
DOI: 10.1387/ijdb.180200mr -
Entropy (Basel, Switzerland) Oct 2022Related to the letters of an alphabet, entropy means the average number of binary digits required for the transmission of one character. Checking tables of statistical...
Related to the letters of an alphabet, entropy means the average number of binary digits required for the transmission of one character. Checking tables of statistical data, one finds that, in the first position of the numbers, the digits 1 to 9 occur with different frequencies. Correspondingly, from these probabilities, a value for the Shannon entropy H can be determined as well. Although in many cases, the Newcomb-Benford Law applies, distributions have been found where the 1 in the first position occurs up to more than 40 times as frequently as the 9. In this case, the probability of the occurrence of a particular first digit can be derived from a power function with a negative exponent > 1. While the entropy of the first digits following an NB distribution amounts to H = 2.88, for other data distributions (diameters of craters on Venus or the weight of fragments of crushed minerals), entropy values of 2.76 and 2.04 bits per digit have been found.
PubMed: 37420433
DOI: 10.3390/e24101413 -
Bulletin of the Hospital For Joint... Jun 2015Since the first successful digit replantation by Japanese surgeons Komatsu and Tamai, the past half century has seen the field of digit replantation in the USA... (Review)
Review
Since the first successful digit replantation by Japanese surgeons Komatsu and Tamai, the past half century has seen the field of digit replantation in the USA experience exponential growth followed by a steady decline in volume of cases and percentage of successful viable digits. The initial enthusiasm and technical progress of digital replantation has been tempered by mediocre functional outcomes, rising healthcare costs, and limited healthcare resources. The history and approach to digit replantation is reviewed and highlights the likely push toward the development of regional replant centers staffed by highly skilled teams to improve the functional outcomes following these complex procedures. More than 50 years have passed since the first successful digit replantation by Komatsu and Tamai who replanted a sharply amputated thumb in a 28-year-old male at the metacarpal-phalangeal joint level in a 4.5 hour procedure. Two arteries and 2 veins were anastomosed using 8-0 monofilament nylon and 7-0 braided silk suture. The patient remained in the hospital for 40 days and did not return to work for 4 months. News of this triumph of microvascular skill was heralded throughout the world as the first successful replantation of a completely amputated digit. Over the past half century, the field of digit replantation in the USA experienced exponential growth followed by a steady decline in volume of cases and percentage of successful viable digits. The initial enthusiasm and technical progress of digital replantation has been tempered by mediocre functional outcomes, rising healthcare costs, and limited healthcare resources. In the next 50 years, it is possible that the majority of digit replantation procedures in the USA may be performed in tertiary centers or regional replant centers by highly skilled teams.
Topics: Amputation, Traumatic; Animals; Biomechanical Phenomena; Finger Injuries; Fingers; History, 20th Century; History, 21st Century; Humans; Postoperative Complications; Recovery of Function; Regeneration; Replantation; Risk Factors; Treatment Outcome
PubMed: 26517169
DOI: No ID Found -
Journal of Exercise Rehabilitation Dec 2016Second to fourth digit ratio is the ratio of second to fourth digit length. It has been known that digit ratio is sexually dimorphic in humans, such that males tend to... (Review)
Review
Second to fourth digit ratio is the ratio of second to fourth digit length. It has been known that digit ratio is sexually dimorphic in humans, such that males tend to have lower digit ratio (longer fourth digits relative to second digits) than females. Digit ratio is thought to be a biomarker of the balance between fetal testosterone (FT) and fetal estrogen (FE) in a relatively narrow developmental window at the end of the first trimester of pregnancy. On the contrary, the relationships between digit ratio and levels of sex steroids in adults are not clear. Most correlational studies between digit ratio and adult sex steroids have revealed that this association is statistically not significant. However, for many years, a lot of researches showed negative relationships between digit ratio and sports performance such as rugby, surfing, rowing, sprinting, endurance, and hand grip strength. Here, we discuss possible mechanisms about the relationships between digit ratio and sports performance.
PubMed: 28119871
DOI: 10.12965/jer.1632862.431 -
The Quarterly Review of Biology Mar 2017The occurrence of supernumerary digits or toes in humans and other tetrapods has attracted general interest since antiquity and later influenced scientific theories of... (Review)
Review
The occurrence of supernumerary digits or toes in humans and other tetrapods has attracted general interest since antiquity and later influenced scientific theories of development, inheritance, and evolution. Seventeenth-century genealogical studies of polydactyly were at the beginning of an understanding of the rules of inheritance. Features of polydactyly were also part of the classical disputes on the nature of development, including the preformation-versus-epigenesis and the atavism-versus-malformation debates. In the evolutionary domain, polydactyly was used in the criticism of the gradualist account of variation underlying Darwin’s theory. Today, extra digit formation plays a role in the conceptualization of gene regulation and pattern formation in vertebrate limb evolution. Recent genetic, experimental, and modeling accounts of extra digit formation highlight the existence of nongradual transitions in phenotypic states, suggesting a distinction between continuous and discontinuous variation in evolution. Unless otherwise noted, all translations are our own.
Topics: Animals; Biological Evolution; Epigenesis, Genetic; Genetic Predisposition to Disease; Heredity; Humans; Inheritance Patterns; Pedigree; Phenotype; Polydactyly
PubMed: 29558608
DOI: 10.1086/690841 -
Journal of Morphology Sep 2022Alvarezsauroidea (Tetanurae) are nonavian theropod dinosaurs whose forelimb evolution is characterised by the overdevelopment of digit I, at the expense of the other two... (Review)
Review
Alvarezsauroidea (Tetanurae) are nonavian theropod dinosaurs whose forelimb evolution is characterised by the overdevelopment of digit I, at the expense of the other two digits, complemented by a drastic forelimb shortening in derived species (Parvicursorinae). These variations are recognised as evolutionary developmental anomalies. Evolutionary teratology hence leads to a double diagnosis with (1) macrodactyly of digit I and microdactyly of digits II and III, plus (2) anterior micromelia. The teratological macrodactyly/microdactyly coupling evolved first. Developmental mechanisms disturbing limb proportion are thought to be convergent with those of other Tetanurae (Tyrannosauridae, Carcharodontosauridae). As for the manual anomalies, both are specific to Alvarezsauroidea (macrodactyly/microdactyly) and inherited (digit loss/reduction). While considering the frame-shift theory, posterior digits develop before the most anterior ones. There would therefore be a decrease in the area devoted to digits II (condensation 3) and III (condensation 4), in connection with the Shh signalling pathway, interacting with other molecular players such as the GLI3 protein and the Hox system. Developmental independence of digit I (condensation 2) would contribute to generating a particular morphology. Macrodactyly would be linked to a variation in Hoxd-13, impacting Gli3 activity, and increasing cell proliferation. The loss/reduction of digital ray/phalanges (digits II and III), would be associated with Shh activity, a mechanism inherited from the theropodan ancestry. The macrodactyly/microdactyly coupling, and then anterior micromelia, fundamentally changed the forelimb mechanical function, compared to the 'classical' grasping structure of basal representatives and other theropods. The distal ossification of the macrodactylian digit has been identified as physiological, implying the use of the structure. However, the debate on a particular 'adaptive' use is pointless as the ecology of an organism is interactively complex, being both at the scale of the individual and dependent on circumstances. Other anatomical features also allow for compensation and different predation (cursorial hindlimbs).
Topics: Animals; Dinosaurs; Fingers; Forelimb; Hindlimb; Limb Deformities, Congenital; Teratology
PubMed: 35915891
DOI: 10.1002/jmor.21500 -
European Journal of Orthopaedic Surgery... Sep 2023The ability to perform surgical replantation of individual digits and limbs can provide substantial functional improvement for patients who sustain devastating upper...
The ability to perform surgical replantation of individual digits and limbs can provide substantial functional improvement for patients who sustain devastating upper extremity injuries. Defining success in replantation surgery extends beyond the acute period and the binary metrics of survival or loss of the replanted part to include the long-term overall functional outcomes. Functional outcomes include both objective clinical evaluation and patient-reported outcomes. There has been significant variation in the way outcomes following replantation are measured, which inherently leads to heterogeneity in the reported outcome data. Given the variability among outcome measures, we aim to explore the outcomes of replantation surgery, particularly clinical evaluation and patient-reported functional outcomes following replantation.
PubMed: 37755559
DOI: 10.1007/s00590-023-03729-1 -
Hand (New York, N.Y.) Jan 2021Digit replantation affords the opportunity to restore hand function following amputation. To date, however, few studies have evaluated functional outcomes following... (Meta-Analysis)
Meta-Analysis Review
Digit replantation affords the opportunity to restore hand function following amputation. To date, however, few studies have evaluated functional outcomes following replantation. Therefore, it was the objective of this study to perform a meta-analysis to better characterize the predictors of hand function. A literature search was performed using the PubMed database to identify studies that focused on digit amputation/replantation and functional outcomes. Studies were evaluated for patient- and injury-related factors and their respective effects on clinical outcomes of sensation, grip strength, and Disabilities of the Arm, Shoulder, and Hand (DASH) scores. Statistical analysis was conducted across the pooled data set to identify significant trends. Twenty-eight studies representing 618 replanted digits were included in this study. We found the average grip strength was 78.7% (relative to contralateral), the average 2-point discrimination (2PD) was 7.8 mm, and the average DASH score was 12.81. After conducting statistical analysis, we found patients with more proximal injuries had lower grip strength scores ( < .05). We found 2PD scores were influenced by age, mechanism of injury, and amputation level ( < .05). Finally, we found DASH scores after replantation were predicted by mechanism of injury and level of amputation ( < .05). The following variables did not influence outcomes: gender, tobacco use, ischemia time, and digit number. Digit replant does not restore premorbid hand function but does result in adequate hand function. Expected functional outcomes following replant should be considered in the decision-making process. These data can help risk-stratify patients, guide postreplant expectations, and influence the decision for replantation.
Topics: Amputation, Surgical; Amputation, Traumatic; Finger Injuries; Humans; Replantation; Retrospective Studies
PubMed: 30938181
DOI: 10.1177/1558944719834658