Anatomical variations of the hand extensors

Abdel-Hamid, Ghada A.; El-Beshbishy, Rana A.; Aal, Iman H. Abdel

doi:10.5603/fm.2013.0040

Cited by 26 publications

(21 citation statements)

References 20 publications

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“…The EPB could be missing in 7.6% (Shigematsu et al, ), in 2.1% (Abdel‐Hamid et al, ), in 0% (Nayak et al, ; Kulshreshtha et al, ), in 2% (Jackson et al, ; Joshi and Joshi, ), in 3.75% (Brunelli and Brunelli, ), in 6.2% (Dawson and Barton, ), and in 5.5% (Wood, 1867, 1868). The average absence frequency is 2.7%.…”

Section: Resultsmentioning

confidence: 99%

The Relationship Between Digit Independence and Digital Sesamoids in Humans and a Proposal of a New Digital Sesamoid Evolutionary Hypothesis

Yammine

2018

The Anatomical Record

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Digital sesamoids are found in the metapodial-phalangeal joints of most mammals and quadrupedal tetrapods, yet their functional significance is still unclear. During primate evolution, a slight decline in their frequency has been associated with brachiation in gibbons, followed by a quasi-complete absence in orangutans then a slight resurgence occurred in gorillas and chimpanzees. Simultaneously, forearm muscles showed a progressive division in hominoid evolution towards a more "individualistic" musculature yielding more mobility and independence to some fingers. In humans, sesamoids are consistently observed in thumbs and big toes and frequently in other hypermobile digits such as the index and little fingers. Using a simple mathematical equation, this paper attempted to quantify a presumed association between hypermobile fingers and sesamoid frequency and distribution in humans. To this, an anatomic definition of digital independence has been formulated which includes three variables; (1) number and (2) frequency of independent flexor/extensor forearm muscles destined to a single finger, (3) and number of free/absent webspace. Results of previous meta-analyses and means of big sample studies were used to evaluate the frequency of such muscles. The expected values obtained via this model were found to be very close to the observed (published) values of the ossified sesamoids in human hands, and that in terms of frequency and distribution. The findings in humans showed a quasi-linear association between the degree of mobility and sesamoid frequency. The more the number of independent muscles destined to a finger, the more its metacarpo-phalangeal joint is likely to bear sesamoids. Based on our results and on a new analysis of primates' forearm/hand muscles and sesamoid evolution, a new hypothesis is proposed to answer two questions; the evolution of digital sesamoid frequency in primates and its sesamoid distribution in human digits. It claims that the number/frequency of independent forearm/hand muscles, and particularly the independent extensors, is likely to be a major factor in sesamoid reversion in hominoids. The argument is based on the link between the metatarsal break induced by the digitigrade locomotion observed in quadrupedal mammals and tetrapods and the amount of extra-extension of the metacarpo-phalangeal joints conferred by the individualization of some forearm extensors. The same rationale yielded similar conclusions when applied to both the hand and foot. The manipulative function of the hand and the plantigrade locomotion of the foot required such extra-extension in specific digits and consequently, a higher frequency of digital sesamoids was associated with these two different functions. The new evolutionary analysis suggests evolutionary pathways for both, the sesamoids of the hands and feet, and speculates that muscle individualization would have induced a very slow re-acquisition of digital sesamoids when compared to their rapid decline after brachiation. It is the first hypothesis offering ...

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Section: Resultsmentioning

confidence: 99%

The Relationship Between Digit Independence and Digital Sesamoids in Humans and a Proposal of a New Digital Sesamoid Evolutionary Hypothesis

Yammine

2018

The Anatomical Record

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“…Forty‐two duplicates were removed and initial screening of the remaining 644 articles yielded 104 potentially relevant, of which 18 narrative reviews and 68 clinical or cadaveric case reports were excluded. References cited in the remaining 18 articles yielded another six relevant studies; so in total, we located 24 cadaveric studies reporting the prevalence of at least one of the primary outcomes (Mori, ; Schenk, 1964; el‐Badawi et al, ; Mestdagh et al, ; Godwin and Ellis, ; Wehbe, ; el‐Badawi et al, ; von Schroeder and Botte, ; Gonzales et al, , ; Komiyama et al, ; Hirai et al, ; Zilber and Oberlin, ; Tanaka et al, ; Celik et al, ; Ranade et al, ; Jeon et al, ; Agarwal and Tirthani, ; Bolwar, ; Dass et al, ; Govsa et al, ; van Aken et al, ; Yoo et al, ; Abdel‐Hamid et al, ).…”

Section: Resultsmentioning

confidence: 99%

“…Fifteen studies reported the prevalence of EDC‐II (Mori, ; Mestdagh et al, ; Godwin and Ellis, ; El‐Badawi et al, ; von Schroeder and Botte, ; Gonzales et al, ; Komiyama et al, ; Hirai et al, ; Zilber and Oberlin, ; Celik et al, ; Ranade et al, ; Agarwal and Tirthani, ; Bolwar, 2011; Dass et al, ; Abdel‐Hamid et al, ) with a total of 2,005 hands and a PPE of 99.8%. The pooled prevalences were 98% (95% CI = 0.960–0.993, I 2 = 85.5%), 1.8% (95% CI = 0.005–0.038, I 2 = 85.1%), and 0.2% (95% CI = 0.0004–0.004, I 2 = 0%) for the single, double, and triple EDC‐II slips, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…Nineteen studies reported the prevalence of EDC‐V (Mori, ; Schenk, 1964; el‐Badawi et al, 1985; Mestdagh et al, ; Godwin and Ellis, ; el‐Badawi et al, ; Gonzales et al, ; von Schroeder and Botte, ; Hirai et al, ; Zilber and Oberlin, ; Tanaka et al, ; Celik et al, ; Jeon et al, ; Agarwal and Tirthani, ; Dass et al, ; Govsa et al, 2011; van Aken et al, 2011; Yoo et al, ; Abdel‐Hamid et al, ) with a total of 1,927 hands and a PPE of 63.2% (95% CI = 0.478–0.772, I 2 = 97.7%). The pooled prevalences from all above studies except that of Yoo et al (), totaling 1333 EDC‐V (in 1,878 hands), were 58.5% (95% CI = 0.414–0.745, I 2 = 97.1%), 10.4% (95% CI = 0.043–0.185, I 2 = 93.6%), 0.94% (95% CI = 0.004–0.015, I 2 = 0%) for the single, double, and triple EDC‐V slips, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…Five studies reported the side‐based prevalences for the three ulnar fingers (Zilber and Oberlin, ; Celik et al, ; Agarwal and Tirthani, ; Dass et al, ; Abdel‐Hamid et al, ) with a total of 205 right and 214 left hands. For EDC‐III, the ORs were 1.1 (95% CI = 0.702–1.820, P = 0.6, I 2 = 13.5%), 1.1 (95% CI = 0.704–1.755, P = 0.6, I 2 = 0%), 0.58 (95% CI = 0.109671–3.140464, P = 0.5, I 2 = 68.2%) for the single‐, double‐, and triple‐slip variant, respectively.…”

Section: Resultsmentioning

confidence: 99%

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The prevalence of the extensor digitorum communis tendon and its insertion variants: A systematic review and meta‐analysis

Yammine

2014

Clinical Anatomy

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The tendons of the Extensor Digitorum Communis (EDC) are frequently injured in hand trauma. Dislocation and spontaneous rupture can also occur during the course of wrist osteoarthritis and rheumatoid arthritis. The EDC exhibits many variations including splitting of its individual slips to the medial four fingers or their absence. The aim of this systematic review is to assemble evidence about the prevalence of the EDC and its variants on the dorsum of the hand. Twenty-four cadaveric studies met the inclusion criteria, providing data from a total of 2,005 hands. Meta-analysis yielded the following results: (a) for EDC-II (Index), the pooled prevalence estimates (PPEs) were 99.8, 98, 1.8, and 0.2% for the total, single, double, and triple slips, respectively; (b) for EDC-III (Middle), the PPEs were 100, 67.7, 24.2, 6, and 0.42% for the total, single, double, triple, and quadruple slips, respectively; (c) for EDC-IV (Ring), the PPEs were 100, 58.6, 29.1, 7.1, and 1.3% for the total, single, double, triple, and quadruple slips, respectively; (d) for EDC-V (Little), the PPEs were 63.2, 58.5, 10.4, 0.94, and 25% for the total, single, double, triple, and common 4th-5th slips, respectively. There were no significant differences in relation to hand side. Many EDC slip variants demonstrated some interaction with ancestry. A sound knowledge of EDC variants and their prevalences is paramount for assessing and treating hand injuries and disorders.

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Anatomy of the extensor mechanism of the thumb in relation to the clinical presentation of extensor pollicis longus rupture

et al. 2019

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Anatomical variations of the hand extensors

Abstract: This study was performed to investigate the anatomy and variations of the human ' data. (Folia Morphol 2013; 72, 3: 249-257)

Cited by 26 publications

References 20 publications

The Relationship Between Digit Independence and Digital Sesamoids in Humans and a Proposal of a New Digital Sesamoid Evolutionary Hypothesis

The Relationship Between Digit Independence and Digital Sesamoids in Humans and a Proposal of a New Digital Sesamoid Evolutionary Hypothesis

The prevalence of the extensor digitorum communis tendon and its insertion variants: A systematic review and meta‐analysis

Anatomy of the extensor mechanism of the thumb in relation to the clinical presentation of extensor pollicis longus rupture

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