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The Journal of Hand Surgery Oct 2020Macrodactyly is a rare, nonhereditary congenital deformity. Digital enlargement in macrodactyly involves all tissue types and presents alone or as part of a congenital...
PURPOSE
Macrodactyly is a rare, nonhereditary congenital deformity. Digital enlargement in macrodactyly involves all tissue types and presents alone or as part of a congenital deformity syndromes. Macrodactyly treatment largely depends on surgeons' experience and knowledge. Because there is a paucity of large cohort studies of macrodactyly in the literature, our goal was to retrospectively analyze macrodactyly cases in order to define a better system for diagnosis, classification, and prognosis.
METHODS
Medical records of 90 Chinese macrodactyly patients, including demographic characteristics, clinical presentations, anatomical distributions, x-rays, pathological findings, and treatments, were reviewed. Genetic analyses of 12 patients were also reviewed.
RESULTS
Disease incidence was similar across sex and geographical regions. Multiple-digit involvement was 2.6 times more frequent than single-digit involvement. The index finger, middle finger, and thumb were most commonly involved. Two digits were affected more often than 3, with the affected digits adjacent in most cases. The affected digit was in the median nerve innervation distribution in 79% of cases and was accompanied by enlargement and fat infiltration of the median nerve. Seven cases had syndactyly. Ten of the 12 cases subjected to PIK3CA mutation analysis were positive.
CONCLUSIONS
Macrodactyly represents a heterogeneous group of conditions, without significant sex or geographical predilection, which is usually present at birth. A high PIK3CA mutation-positive rate in affected tissues suggests a similar cellular mechanism for overgrowth in patients with various clinical presentations.
TYPE OF STUDY/LEVEL OF EVIDENCE
Prognostic IV.
Topics: Fingers; Humans; Infant, Newborn; Limb Deformities, Congenital; Retrospective Studies; Syndactyly
PubMed: 32299688
DOI: 10.1016/j.jhsa.2020.03.002 -
Journal of Neurophysiology Oct 2019It is tempting to describe human reach-to-grasp movements in terms of two, more or less independent visuomotor channels, one relating hand transport to the object's... (Review)
Review
It is tempting to describe human reach-to-grasp movements in terms of two, more or less independent visuomotor channels, one relating hand transport to the object's location and the other relating grip aperture to the object's size. Our review of experimental work questions this framework for reasons that go beyond noting the dependence between the two channels. Both the lack of effect of size illusions on grip aperture and the finding that the variability in grip aperture does not depend on the object's size indicate that size information is not used to control grip aperture. An alternative is to describe grip formation as emerging from controlling the movements of the digits in space. Each digit's trajectory when grasping an object is remarkably similar to its trajectory when moving to tap the same position on its own. The similarity is also evident in the fast responses when the object is displaced. This review develops a new description of the speed-accuracy trade-off for multiple effectors that is applied to grasping. The most direct support for the digit-in-space framework is that prism-induced adaptation of each digit's tapping movements transfers to that digit's movements when grasping, leading to changes in grip aperture for adaptation in opposite directions for the two digits. We conclude that although grip aperture and hand transport are convenient variables to describe grasping, treating grasping as movements of the digits in space is a more suitable basis for understanding the neural control of grasping.
Topics: Fingers; Hand Strength; Humans; Illusions; Motor Skills; Movement; Size Perception
PubMed: 31339802
DOI: 10.1152/jn.00123.2019 -
Journal of Bone and Mineral Research :... Feb 2022Amputation of the mouse digit tip results in blastema-mediated regeneration. In this model, new bone regenerates de novo to lengthen the amputated stump bone, resulting...
Amputation of the mouse digit tip results in blastema-mediated regeneration. In this model, new bone regenerates de novo to lengthen the amputated stump bone, resulting in a functional replacement of the terminal phalangeal element along with associated non-skeletal tissues. Physiological examples of bone repair, such as distraction osteogenesis and fracture repair, are well known to require mechanical loading. However, the role of mechanical loading during mammalian digit tip regeneration is unknown. In this study, we demonstrate that reducing mechanical loading inhibits blastema formation by attenuating bone resorption and wound closure, resulting in the complete inhibition of digit regeneration. Mechanical unloading effects on wound healing and regeneration are completely reversible when mechanical loading is restored. Mechanical unloading after blastema formation results in a reduced rate of de novo bone formation, demonstrating mechanical load dependence of the bone regenerative response. Moreover, enhancing the wound-healing response of mechanically unloaded digits with the cyanoacrylate tissue adhesive Dermabond improves wound closure and partially rescues digit tip regeneration. Taken together, these results demonstrate that mammalian digit tip regeneration is mechanical load-dependent. Given that human fingertip regeneration shares many characteristics with the mouse digit tip, these results identify mechanical load as a previously unappreciated requirement for de novo bone regeneration in humans. © 2021 American Society for Bone and Mineral Research (ASBMR).
Topics: Amputation, Surgical; Animals; Bone Regeneration; Bone and Bones; Mice; Osteogenesis; Wound Healing
PubMed: 34783092
DOI: 10.1002/jbmr.4470 -
Developmental Biology Jun 2022It is long-established that innervation-dependent production of neurotrophic factors is required for blastema formation and epimorphic regeneration of appendages in fish...
It is long-established that innervation-dependent production of neurotrophic factors is required for blastema formation and epimorphic regeneration of appendages in fish and amphibians. The regenerating mouse digit tip and the human fingertip are mammalian models for epimorphic regeneration, and limb denervation in mice inhibits this response. A complicating issue of limb denervation studies in terrestrial vertebrates is that the experimental models also cause severe paralysis therefore impairing appendage use and diminishing mechanical loading of the denervated tissues. Thus, it is unclear whether the limb denervation impairs regeneration via loss of neurotrophic signaling or loss of mechanical load, or both. Herein, we developed a novel surgical procedure in which individual digits were specifically denervated without impairing ambulation and mechanical loading. We demonstrate that digit specific denervation does not inhibit but attenuates digit tip regeneration, in part due to a delay in wound healing. However, treating denervated digits with a wound dressing that enhances closure results in a partial rescue of the regeneration response. Contrary to the current understanding of mammalian epimorphic regeneration, these studies demonstrate that mouse digit tip regeneration is not peripheral nerve dependent, an observation that should inform continued mammalian regenerative medicine approaches.
Topics: Amputation, Surgical; Animals; Denervation; Extremities; Mammals; Mice; Wound Healing
PubMed: 35353991
DOI: 10.1016/j.ydbio.2022.03.007 -
The South African Journal of Psychiatry... 2021Schizophrenia is a debilitating mental health condition affecting the lives of many South Africans. The origins of the heterogeneity in the presentation of the illness...
BACKGROUND
Schizophrenia is a debilitating mental health condition affecting the lives of many South Africans. The origins of the heterogeneity in the presentation of the illness remain uncertain.
AIM
This cross-sectional study performed a retrospective data analysis to determine the usefulness of digit ratio as an endophenotype in a South African schizophrenia population.
SETTING
A large genetic study in a South African schizophrenia population recruited patients from services in the Western and Eastern Cape.
METHODS
Complete clinical histories were captured for participants, including sets of images of the face and extremities. Software was utilised to measure the lengths of participants' digits from said images and digit ratios (2D:4D) were calculated. Descriptive analyses were performed on the ratios and statistical differences in digit ratio means were calculated between groups characterised by sex, age of onset and the presence vs absence of positive symptoms. Linear modelling was utilised to assess for correlates between 2D:4D and positive and negative symptom severity using scores obtained from the Positive and Negative Syndrome Scale (PANSS) and Scale for the Assessment of Negative Symptoms (SANS).
RESULTS
2D:4D in male participants did not significantly differ from female participants as in healthy populations. 2D:4D did not significantly correlate with the severity of positive or negative symptoms and 2D:4D means between groups did not significantly relate to age of onset.
CONCLUSION
2D:4D appears to be a possible endophenotype in schizophrenia in this population. 2D:4D, however, may not be as readily identifiable as certain minor physical anomalies and neurological soft signs significantly associated with schizophrenia in this population.
PubMed: 33824756
DOI: 10.4102/sajpsychiatry.v27i0.1587 -
International Journal of Molecular... Mar 2021Nails are highly keratinized skin appendages that exhibit continuous growth under physiological conditions and full regeneration upon removal. These mini-organs are... (Review)
Review
Nails are highly keratinized skin appendages that exhibit continuous growth under physiological conditions and full regeneration upon removal. These mini-organs are maintained by two autonomous populations of skin stem cells. The fast-cycling, highly proliferative stem cells of the nail matrix (nail stem cells (NSCs)) predominantly replenish the nail plate. Furthermore, the slow-cycling population of the nail proximal fold (nail proximal fold stem cells (NPFSCs)) displays bifunctional properties by contributing to the peri-nail epidermis under the normal homeostasis and the nail structure upon injury. Here, we discuss nail mini-organ stem cells' location and their role in skin and nail homeostasis and regeneration, emphasizing their importance to orchestrate the whole digit tip regeneration. Such endogenous regeneration capabilities are observed in rodents and primates. However, they are limited to the region adjacent to the nail's proximal area, indicating the crucial role of nail mini-organ stem cells in digit restoration. Further, we explore the molecular characteristics of nail mini-organ stem cells and the critical role of the bone morphogenetic protein (BMP) and Wnt signaling pathways in homeostatic nail growth and digit restoration. Finally, we investigate the latest accomplishments in stimulating regenerative responses in regeneration-incompetent injuries. These pioneer results might open up new opportunities to overcome amputated mammalian digits and limbs' regenerative failures in the future.
Topics: Animals; Cell Differentiation; Epidermal Cells; Extremities; Homeostasis; Humans; Nails; Regeneration; Skin; Stem Cells
PubMed: 33799809
DOI: 10.3390/ijms22062864 -
JAMA Network Open Oct 2021Risk-adjusted variation in surgeon outcomes has been traditionally explained by surgeon volume and hospital infrastructure, yet it is unclear how a surgeon's operative...
IMPORTANCE
Risk-adjusted variation in surgeon outcomes has been traditionally explained by surgeon volume and hospital infrastructure, yet it is unclear how a surgeon's operative proficiency directly contributes to their patients' outcomes.
OBJECTIVE
To assess the variation of surgeons' operative proficiency and investigate its association with surgical outcomes.
DESIGN, SETTING, AND PARTICIPANTS
This case series was a retrospective analysis of all digit replantations and revascularizations at a single US university medical center between January 2000 and August 2020. Surgeons were assigned a proficiency score based on the expected procedure difficulty and outcomes from a sample of their cases. Surgeon proficiency scores were then used to determine associations with outcomes from subsequent cases. The expected difficulty of each case was calculated using a novel scoring system that applied pooled relative risks from a meta-analysis of risk factors for replantation and revascularization failure.
EXPOSURES
Digit replantation and revascularization.
MAIN OUTCOMES AND MEASURES
Digit survival at 1-month follow up (case success) and number of complications.
RESULTS
A total of 145 patients and 226 digits were treated by 11 surgeons with training in hand or microsurgery (mean [SD] age, 41.9 [15.2] years; 204 [90%] men); there were 116 replantations and 110 revascularizations. Surgeon proficiency scores ranged from 1.3 to 5.7, with a mean (SD) of 3.4 (1.4). Case success rates among surgeons varied from 20.0% to 90.5%, with a mean (SD) of 64.9%. Higher proficiency scores were associated with fewer case failures: each point increase was associated with 40% decreased odds of failure (odds ratio, 0.60; 95% CI, 0.38-0.94). Every 3-point increase in proficiency score was associated with 1 less complication (effect estimate, -0.29; 95% CI, -0.56 to 0.02). Surgeon proficiency score had a greater association with case failure than surgeon volume (16.7% vs 12.0%). The final model's association with case failure had an area under the receiver operating characteristics curve of 0.93.
CONCLUSIONS AND RELEVANCE
Operative proficiency varied widely among practicing surgeons and accounted for 17% of estimative ability for success of digit replantation and revascularization. Greater surgeon proficiency was associated with better outcomes, indicating that the value of surgical care may be optimized by improving surgeon proficiency.
Topics: Adult; Amputation, Surgical; Clinical Competence; Female; Fingers; Humans; Logistic Models; Male; Middle Aged; Odds Ratio; Propensity Score; Replantation; Retrospective Studies; Surgeons; Treatment Outcome
PubMed: 34698849
DOI: 10.1001/jamanetworkopen.2021.28765 -
Plastic Surgery (Oakville, Ont.) Feb 2023Understanding the variables that influence success in digital replant surgery is essential to guide clinical decision-making and to counsel patients. The purpose of...
Understanding the variables that influence success in digital replant surgery is essential to guide clinical decision-making and to counsel patients. The purpose of this study was to determine the replant success rate and identify predictors of success at our tertiary care centre. This was a single centre, retrospective cohort study of consecutive patients who underwent digital replantation from January 2000 to September 2018. Adult patients with flexor zone I to III amputations were included. Patient demographics, comorbidities, injury pattern, operative data, and post-operative care were reviewed. The primary outcome was survival of the replanted digit at discharge. A total of 146 patients met inclusion criteria. Of these, 100 had single-digit replants and 46 underwent multi-digit replants for a total of 220 digits. The success rate was 71%. Predictors of success included sharp mechanism of injury (P < .01), incomplete amputation (P < .01), amputation proximal to zone I flexor level (P = .02), post-operative acetylsalicylic acid use (P < .01), absence of leech use (P = .05), and absence of operative re-exploration (P < .01). Daytime replants had similar outcome compared to nighttime replants despite having increased ischemia time (7.9 ± 3.9 hours vs 6.8 ± 2.6 hours, P = .02). However, daytime operative time (7.8 ± 3.7 hours) was significantly shorter than nighttime replant time (9.6 ± 5.9 hours, P = .01). Sharp amputation, intact venous drainage, proximal amputation, and acetylsalicylic acid use were associated with replant survival and are factors to consider when managing patients for digital replantation. Leech therapy and operative re-exploration were associated with poor outcome. Nighttime replants required significantly longer operative time than daytime replants despite similar survival outcome.
PubMed: 36755824
DOI: 10.1177/22925503211024767 -
Human Movement Science Oct 2022In the referent control theory, grip force emerges by designating the referent aperture (R) as a threshold position inside the object. This study quantified R and...
In the referent control theory, grip force emerges by designating the referent aperture (R) as a threshold position inside the object. This study quantified R and investigated whether the synergistic control of digit referent coordinate (RC) and apparent stiffness (k) depend on the external mechanical constraints on the hand-held object. Subjects held a motorized handle capable of adjusting the grip width and performed static multi-digit prehension tasks in which the handle was free and externally fixed in different conditions. The RC and k of individual digits were reconstructed from the changes in digit normal forces and the positions as the grip width was modulated. RCs of the thumb and virtual finger were used to calculate the width and midpoint of R, and synergy indices quantifying the task-specific covariation in the space of the digit normal forces and {RC, k} variables were computed. We found that the k and width of the R were larger when holding a free handle than the fixed handle. The higher stiffness in the free condition could be a strategy to ensure grip stability. The midpoint of R was skewed toward the virtual finger, reflecting different magnitudes of k for the two digits. Further, the normal forces and control variables {RC, k} displayed synergistic covariation for stabilization of the total grasping force. Finally, the synergies were weaker when the handle was externally fixed, demonstrating the dependence of synergies on external constraints. These results add to the current literature by demonstrating that grasp control involves modulation of digit apparent stiffness in addition to the referent coordinate and by identifying the synergistic organization of the control variables during static grasp.
Topics: Fingers; Hand Strength; Humans; Movement; Psychomotor Performance; Thumb
PubMed: 35986961
DOI: 10.1016/j.humov.2022.102994 -
Developmental Cell Apr 2022During embryonic development, digits gradually emerge in a periodic pattern. Although genetic evidence indicates that digit formation results from a self-organizing...
During embryonic development, digits gradually emerge in a periodic pattern. Although genetic evidence indicates that digit formation results from a self-organizing process, the underlying mechanisms are still unclear. Here, we find that convergent-extension tissue flows driven by active stresses underlie digit formation. These active stresses simultaneously shape cartilage condensations and lead to the emergence of a compressive stress region that promotes high activin/p-SMAD/SOX9 expression, thereby defining digit-organizing centers via a mechanical feedback. In Wnt5a mutants, such mechanical feedback is disrupted due to the loss of active stresses, organizing centers do not emerge, and digit formation is precluded. Thus, digit emergence does not result solely from molecular interactions, as was previously thought, but requires a mechanical feedback that ensures continuous coupling between phalanx specification and elongation. Our work, which links mechanical and molecular signals, provides a mechanistic context for the emergence of organizing centers that may underlie various developmental processes.
Topics: Activins; Chondrogenesis; Extremities; Feedback; Gene Expression Regulation, Developmental; Morphogenesis
PubMed: 35413235
DOI: 10.1016/j.devcel.2022.03.004