Update on embryology of the upper limb

Accessory Flexor Carpi Ulnaris Muscle in Humans: A Rare Anatomical Case with Clinical Considerations

Anatomical variations of the forearm flexor muscles are occasionally encountered. Though usually observed incidentally during autopsies or imaging studies, they may at times cause concern due to associated clinical symptoms. This report presents a case of unilateral accessory flexor carpi ulnaris (AFCU) muscle observed in a human male cadaver aged 78 years. During routine cadaveric dissection, an anomalous AFCU muscle was observed in the left forearm of a human male cadaver aged 78 years. Standard institutional guidelines pertaining to the use of human cadaver for teaching and research were followed. A thorough literature review about the flexor carpi ulnaris (FCU) through the PubMed, Embase and Google scholar databases was undertaken, using the keywords - accessory flexor carpi ulnaris muscle, aberrant flexor carpi ulnaris muscle and anatomical variation of flexor carpi ulnaris muscle. Relevant gross anatomical findings were recorded and photographed. AFCU was identified on the medial aspect of the distal third of the left forearm. The AFCU was found originating from the ante-brachial fascia and the fascia covering the FCU on the left forearm, forming a small separate belly deep to the main muscle. It terminated as a thin tendon running alongside the hypothenar muscles and attached distally to the base of the proximal phalanx of the little finger. The AFCU was found to be innervated by a branch of the ulnar nerve. Awareness about the rare AFCU muscle is clinically important as a possible cause of ulnar nerve compression but also as a possible graft in reconstruction surgeries.

My journey in hand surgery: combining patient care, clinical and basic science research

This review is about my clinical and research journey in hand surgery. The journey has been a worthwhile and meaningful one, especially when I felt there were areas I could influence management, whether this be rare cases, common conditions or where a suggested algorithm may be helpful. I also had the unique privilege of working with geneticists, which has resulted in clinical-pathological publications that could influence patient management, as shared from a clinician's perspective. It is hoped this article will inspire young clinician scientists to pursue a journey of collaboration with other researchers.

Epidemiology of Congenital Upper-Limb Anomalies in Southern Taiwan Based on the Updated Oberg, Manske, and Tonkin Classification: A Series of 1,335 Anomalies in 1,188 Patients

PURPOSE

This study aimed to investigate the relative frequency of congenital upper-limb anomalies (CULAs) in southern Taiwan using the 2020-updated the Oberg, Manske, and Tonkin (OMT) classification system and evaluate the practicality of the new classification system.

METHODS

We retrospectively reviewed patients with CULAs from 1987 to 2021 at a referral center in southern Taiwan. All patients were analyzed based on medical records, photographs, and radiographs, and the anomalies were classified according to the 2020 OMT classification system.

RESULTS

A total of 1,188 patients with 1,335 CULAs were retrospectively reviewed. The results demonstrated that the most common type of CULA was malformations (1,092 cases), followed by dysplasias (144 cases), syndromes (51 cases), and deformations (48 cases). Among the malformations, radial polydactyly was the most common anomaly (732 cases), followed by simple syndactyly (66 cases). Among the dysplasias, camptodactyly was the most common anomaly (52 cases), followed by thumb-in-palm deformity (45 cases) and vascular tumors (17 cases). In the deformations, constriction ring sequence accounted for all cases. Poland syndrome (21 cases) occurred most often in the category of syndromes.

CONCLUSIONS

The results of this study show that radial polydactyly (732 cases, 55%) is the most common CULA in southern Taiwan, followed by simple syndactyly (66 cases, 5%) and then camptodactyly (52 cases, 4%).

CLINICAL RELEVANCE

The OMT classification system is reasonably practical for precise classification of CULAs and enables easy comparison of studies over different time periods. However, continually updating the OMT classification system is required to better categorize the highly variable presentations of CULAs.

Camptodactyly: From Embryological Basis to Surgical Treatment

Camptodactyly is a relatively rare hand deformity presenting as the proximal interphalangeal joint's nontraumatic and progressive flexion contracture. Most cases are limited to the fifth finger. The severity and type of camptodactyly should be considered to optimize treatment. Since many structures at the finger base can be involved in the pathogenesis of the deformity, surgical treatment for this particular type of deformity is challenging. This paper aims to bring insight into camptodactyly's pathogenesis and treatment options. We discuss the indication and pitfalls of surgical treatment options for particular camptodactyly types and present a case of a fourteen-year-old boy who was admitted to our department with proximal interphalangeal joint flexion contracture of the left fifth digit.

Genetics, Clinical Presentation, Radiological Features, and Midterm Outcome of Closing Wedge Osteotomy in Children With Brachydactyly Type C

BACKGROUND

Brachydactyly (BD) type C is a rare form of familial BD caused by GDF5 mutations. Some of the affected children have severe clinodactyly requiring surgery. The literature is limited to case reports.

PATIENTS AND METHODS

The current retrospective study included 15 Saudi Arabian families with 42 affected children seen by the author for 25 years. A total of 23 digits (in 23 hands) underwent surgical correction of clinodactyly using a closing wedge osteotomy. The current study reports on the genetics, clinical presentation, radiological features, and midterm outcome of surgery.

RESULTS

Genetic analysis was done in 6 families and confirmed the presence of 2 novel missense mutations (p.Met173Val in 3 families and p.Thr203Asn in 3 families) in the GDF5 gene. All cases in the study group demonstrated the classical clinical and radiographic features of BD type C. However, only 1 hand showed all the features of angel-shaped bony defect. The clinodactyly defect was mostly observed in the index or middle fingers. Surgery for the clinodactyly defect was only done if there was finger overlap. Closing wedge osteotomy was done in a total of 23 digits with a satisfactory outcome.

CONCLUSIONS

This study represents the largest reported series of children undergoing surgery for correction of BD type C clinodactyly with a uniform technique performed by a single surgeon. The closing wedge osteotomy used resulted in good midterm outcomes, although long-term follow-up is lacking.

Preoperative MRI Evaluation of Hand Vessels in Children With Congenital Syndactyly Malformation by a Contrast-Enhanced Three-Dimensional Water-Selective Cartilage Scan

BACKGROUND

It is crucial to preoperatively assess the arteries of the hands in congenital syndactyly malformation (CSM) patients because this information can affect the therapeutic outcome and prognosis.

OBJECTIVE

To investigate the value of a contrast-enhanced three-dimensional water-selective cartilage scan for the preoperative evaluation of CSM in children.

MATERIALS AND METHODS

Contrast-enhanced three-dimensional water-selective cartilage scan 3.0 T magnetic resonance imaging (MRI) performed in 16 clinically diagnosed CSM patients with 17 affected hands. The arteries of the hands were displayed with a focus on the bifurcation position of the common palmar digital arteries (CPDAs) and the maturity of the proper palmar digital arteries (PPDAs). The MRI results were interpreted by consensus between two experienced pediatric radiologists with 10 years of MRI experience each. The MRI findings were compared with the operation results.

RESULTS

Of 51 CPDAs in the 17 affected hands, MRI showed that 30 had an abnormal bifurcation position and 20 had a normal position, and of the 102 PPDAs, 14 were shown to have an abnormal maturity and 85 a normal state, which were confirmed by surgery. The accuracy, sensitivity and specificity for determining the bifurcation position of the CPDAs based on MR maximum intensity projection reconstructed images were 98.04% (50/51), 96.77% (30/31) and 100% (20/20), respectively. The maturity of the PPDAs was judged by MR maximum intensity projection reconstructed images with an accuracy, sensitivity and specificity of 97.06% (99/102), 82.35% (14/17) and 100% (85/85), respectively.

CONCLUSION

Contrast-enhanced three-dimensional water-selective cartilage scan has excellent performance in displaying the bifurcation position of the CPDAs and the maturity of the PPDAs and is of high value for the preoperative evaluation of CSM in children.

The Classification of VACTERL Association into 3 Groups According to the Limb Defect

The VACTERL association (VA) is defined as the nonrandom co-occurrence of 6 anomalies: vertebral anomalies (V), Anal atresia (A), Cardiac defects (C), Tracheo-esophageal fistula (TE), Renal defects (R), and Limb anomalies (L). The current communication presents an argument that patients with VA should be classified into three district groups based on their limb defects: VACTERL1: patients with normal limbs; VACTERL2: patients with limb anomalies other than radial ray defects of the upper limbs; and VACTERL3: patients with radial ray defects of the upper limbs. The author will demonstrate that the rationale behind the L1-3 classification in patients in VA is based on the embryogenesis of the 6 affected anatomical areas in VA. The pathogenesis of VACTERL1 is secondary to perturbations of Sonic Hedgehog (SHH) interactions. SHH signaling is known to have a major role in the normal development of the vertebrae, ano-rectal area, heart, tracheo-esophageal area, and kidney. However, SHH is not involved in the development of the radial ray; hence, patients present with no limb defects. The pathogenesis of VACTERL2 is variable depending on the type of gene mutation. The pathogenesis of VACTERL3 is related to errors in a group of proteins (namely, the proteins of the TBX5-SALL4-SALL1 loop and the FGF8-FGF10 loop/ pathway). These proteins are essential for the normal development of the radial ray and they interact in the development of the other anatomical areas of VA including the heart and kidney. Hence, VACTERL3 patients present with radial ray deficiency.

Evaluation and Management of Preaxial Polydactyly

PURPOSE OF REVIEW

To provide a current review of the embryology, classification, evaluation, surgical management, and clinical outcomes related to preaxial polydactyly.

RECENT FINDINGS

Recent studies include a proposed embryologic link between preaxial polydactyly and other congenital abnormalities, an evaluation of long-term postsurgical outcomes, and an examination of important predictors for postsurgical outcomes. Preaxial polydactyly, while relatively uncommon, is a complex congenital hand abnormality that requires careful preoperative classification and proper surgical intervention timing to yield optimal outcomes.

Oberg-Manske-Tonkin Classification of Congenital Upper Extremity Anomalies: The First Report From Turkey

PURPOSE

Although the Oberg-Manske-Tonkin (OMT) classification has been recommended by the International Federation of Societies for Surgery of the Hand owing to some insufficiencies of the Swanson classification system, it has not achieved a universal adoption by hand surgeons. In this study, we hypothesize that the OMT classification can be used easily to classify congenital upper extremity anomalies. We also aim to make epidemiological analysis of congenital upper extremity anomalies with the OMT classification and to compare the applicability of the OMT and the Swanson classifications.

METHODS

We retrospectively analyzed 711 patients and 833 extremities operated on between 2012 and 2017. Photographs, plain x-rays, and brief medical histories of the patients were evaluated by 4 plastic surgeons. Two independent evaluations were made by each surgeon in 1-month interval using these classification systems.

RESULTS

Total number of upper extremity anomalies recorded was 1050. Of the 711 patients operated on, 122 had bilateral anomalies. The anomalies were identified in 833 extremities because many extremities had more than a single diagnosis. We were able to classify all of the anomalies within the OMT classification. The OMT classification gives better reliability results compared with the Swanson classification according to intrarater and interrater reliabilities.

CONCLUSIONS

Compared with the Swanson classification system based on phenotypic evaluation of the extremity, the OMT classification system is easier to apply and the association of the anomaly with the embryologic origin during evaluation is possible. We believe that multiple studies from different centers will boost the international acceptance of the OMT classification.

GLI3: a mediator of genetic diseases, development and cancer

The transcription factor GLI3 is a member of the Hedgehog (Hh/HH) signaling pathway that can exist as a full length (Gli3-FL/GLI3-FL) or repressor (Gli3-R/GLI3-R) form. In response to HH activation, GLI3-FL regulates HH genes by targeting the GLI1 promoter. In the absence of HH signaling, GLI3 is phosphorylated leading to its partial degradation and the generation of GLI3-R which represses HH functions. GLI3 is also involved in tissue development, immune cell development and cancer. The absence of Gli3 in mice impaired brain and lung development and GLI3 mutations in humans are the cause of Greig cephalopolysyndactyly (GCPS) and Pallister Hall syndromes (PHS). In the immune system GLI3 regulates B, T and NK-cells and may be involved in LPS-TLR4 signaling. In addition, GLI3 was found to be upregulated in multiple cancers and was found to positively regulate cancerous behavior such as anchorage-independent growth, angiogenesis, proliferation and migration with the exception in acute myeloid leukemia (AML) and medulloblastoma where GLI plays an anti-cancerous role. Finally, GLI3 is a target of microRNA. Here, we will review the biological significance of GLI3 and discuss gaps in our understanding of this molecule. Video Abstract.

Treatment of congenital syndactyly

Defined as the union of two adjacent digits, syndactyly is one of the most common congenital deformities. The severity of the malformation depends on the fusion level, the tissues involved in the union, and whether it is isolated or syndromic. In order to improve the hand's appearance and function, surgery is recommended in the great majority of cases, ideally during early childhood (i.e., before entering school). Web space reconstruction is done using local flaps. Depending on the flap design, digital resurfacing can be done with or without skin grafts. While graftless techniques have shorter operating times and no morbidity associated with skin harvesting, their cosmetic outcomes seem to be worse than those of traditional grafting techniques, with more postoperative complications; furthermore, such techniques cannot be used in all cases, especially those with osteoarticular fusions. When the fingertip is involved, paronychial reconstruction is carried out with pulp flaps. The prognosis for these deformities directly depends on their severity, with excellent outcomes in cases of cutaneous fusion, and much less predictable ones when osteoarticular and/or tendinous tissues are involved.

Dorsal and Ventral Dimelia in the Same Hand in A Patient with Severe Ulnar Ray Deficiency: A Case Report

Dorsal dimelia (the appearance of dorsal hand structures on the palmar aspect of the hand) and ventral dimelia (the appearance of ventral hand structures on the dorsal aspect of the hand) are rare congenital anomalies of the hand. None of the previously reported cases had combined dorsal and ventral dimelia in the same patient. Here, we report a case of severe ulnar ray deficiency. The hand had two digits: the radial digit had a palmar nail (dorsal dimelia) and the ulnar digit had absence of the normal dorsal nail along with the appearance of an ectopic pulp on the dorsal aspect of the digit (ventral dimelia). Ulnar ray deficiency is an error of sonic hedgehog (SHH) responsible for antero-posterior patterning of the limb in-utero. Ventral and dorsal dimelia are errors of dorso-ventral patterning of the hand. The complex interactions of SHH with the dorso-ventral axis of development may explain the concurrent dimelia in our patient.

A Review of the Genetics and Pathogenesis of Syndactyly in Humans and Experimental Animals: A 3-Step Pathway of Pathogenesis

Embryology of normal web space creation and the genetics of syndactyly in humans and experimental animals are well described in the literature. In this review, the author offers a 3-step pathway of pathogenesis for syndactyly. The first step is initiated either by the overactivation of the WNT canonical pathway or the suppression of the Bone Morphogenetic Protein (BMP) canonical pathway. This leads to an overexpression of Fibroblast Growth Factor 8 (FGF8). The final step is the suppression of retinoic acid in the interdigital mesenchyme leading to suppression of both apoptosis and extracellular matrix (ECM) degradation, resulting in syndactyly.

Classification of congenital upper limb anomalies: towards improved communication, diagnosis, and discovery

Recently the International Federation of Societies for Surgery of the Hand replaced the Swanson scheme for classifying congenital upper limb anomalies with the Oberg, Manske, Tonkin (OMT) classification. This review explores the reasons for this change after nearly 50 years of using the Swanson classification. In particular, it documents the state of our understanding regarding genetics and limb development at the time Swanson generated his classification. It also describes the continued progress in clinical genetics and developmental biology. Such progress drives the need to embrace and incorporate these changes within a new classification scheme; one that will improve communication, diagnosis, and support further discovery of the pathogenesis of congenital hand anomalies.

Severity of ulnar deficiency and its relationship with lower extremity deficiencies

To assess the characteristics of ulnar deficiency (UD) and their relationship to lower extremity deficiencies, we retrospectively classified 82 limbs with UD in 62 patients, 55% of whom had femoral, fibular, or combined deficiencies. In general, UD severity classification at one level (elbow, ulna, fingers, thumb/first web space) statistically correlated with similar severity at another. Ours is the first study to show that presence of a lower limb deficiency is associated with less severe UD on the basis of elbow, ulnar, and thumb/first web parameters. This is consistent with the embryological timing of proximal upper extremities developing before the lower extremities.

The Impact of Microsurgery on Congenital Hand Anomalies Associated with Amniotic Band Syndrome

Supplemental Digital Content is available in the text.

Background:

Amniotic Band Syndrome is a clinical constellation of congenital anomalies characterized by constricting rings, tissue synechiae and amputation of body parts distal to the constriction bands. Involvement of the hand with loss of multiple digits not only leads to devastating deformities but also loss of functionality.

Methods:

In this series, utilizing microvascular transfer of the second toe from both feet, along with local tissue reconfiguration, a tetra-digital hand with simile of normal cascade was reconstructed. A consecutive series of eight children with Amniotic Band Syndrome, younger than two years in age operated on by single surgeon over a twenty five year interval was reviewed.

Results:

There was no flap loss. The hands were sensate with effective simple prehensile function.

Conclusion:

Application of Microvascular toe-to-hand transfer for well selected, albeit severe hand deformity in Amniotic Band Syndrome is a valid surgical concept.

Copy-number variants and candidate gene mutations in isolated split hand/foot malformation

Split hand/foot malformation (SHFM) is a congenital limb deficiency with missing or shortened central digits. Some SHFM genes have been identified but the cause of many SHFM cases is unknown. We used single-nucleotide polymorphism (SNP) microarray analysis to detect copy-number variants (CNVs) in 25 SHFM cases without other birth defects from New York State (NYS), prioritized CNVs absent from population CNV databases, and validated these CNVs using quantitative real-time polymerase chain reaction (qPCR). We tested for the validated CNVs in seven cases from Iowa using qPCR, and also sequenced 36 SHFM candidate genes in all the subjects. Seven NYS cases had a potentially deleterious variant: two had a p.R225H or p.R225L mutation in TP63, one had a 17q25 microdeletion, one had a 10q24 microduplication and three had a 17p13.3 microduplication. In addition, one Iowa case had a de novo 10q24 microduplication. The 17q25 microdeletion has not been reported previously in SHFM and included two SHFM candidate genes (SUMO2 and GRB2), while the 10q24 and 17p13.3 CNVs had breakpoints within genomic regions that contained putative regulatory elements and a limb development gene. In SHFM pathogenesis, the microdeletion may cause haploinsufficiency of SHFM genes and/or deletion of their regulatory regions, and the microduplications could disrupt regulatory elements that control transcription of limb development genes.

GLI3-related polydactyly: a review

GLI3 mutations are known to be associated with nine syndromes/conditions in which polydactyly is a feature. In this review, the embryology, pathogenesis, and animal models of GLI3-related polydactyly are discussed first. This is followed by a detailed review of the genotype-phenotype correlations. Based on our review of the literature and our clinical experiences, we recommend viewing GLI3-related syndromes/conditions as four separate entities; each characterized by a specific pattern of polydactyly. These four entities are: the preaxial polydactyly type IV-Greig-acrocallosal spectrum, postaxial polydactyly types A/B, Pallister-Hall syndrome (PHS), and oral-facial-digital overlap syndrome. We also provide illustrative clinical examples from our practice including a family with a novel GLI3 mutation causing PHS. The review also introduces the term 'Forme Fruste' preaxial polydactyly and gives several conclusions/recommendations including the recommendation to revise the current criteria for the clinical diagnosis of PHS.

The pathogenesis of congenital radial head dislocation/subluxation

The pathogenesis of congenital radial head dislocation/subluxation is unknown and has not been previously investigated. In this review, we explore the pathogenesis and define five different primary insults: collagen abnormalities, abnormal endochondral ossification of the developing growth plate, abnormalities of forearm ossification outside the growth plate, disproportionate growth of the radius and ulna, and altered HOX D expression/activity. Finally, the clinical relevance of our review is discussed.

Radiological imaging of congenital hand anomalies--a 6-year single-centre experience and what the hand surgeons want to know

OBJECTIVE

Congenital hand anomalies present a rare but important physical and emotional challenge for children and parents. Radiological imaging is important for accurate diagnosis, to aid decision making and to monitor changes in the growing hand. The goal of any treatment is to help the child achieve his/her maximum potential, to provide a useful hand with attention to cosmesis. We investigated the range of congenital hand anomalies imaged in a tertiary referral centre. We examined the timing of imaging and the key clinical questions.

METHODS

The radiology imaging system was searched retrospectively for radiographs of congenital hand anomalies over a 6-year period. The images were reviewed and patient demographics, diagnosis and other imaging recorded.

RESULTS

Over 6 years, 85 patients had imaging. Twenty-three patients had bilateral problems and 11 had recognised syndromes. The most common abnormalities imaged were duplicated thumbs (28 %), followed by syndactyly (18 %). Children were first imaged as early as 1 day old, with the median age of initial imaging 12 months.

CONCLUSIONS

Thumb duplication and syndactyly are the most common conditions for which radiographs are requested at our hospital, although overall syndactyly is considered the most common congenital hand anomaly. For a variety of reasons, children are often imaged very early, before review by the Specialist in Children's Hand Surgery (despite surgery being unlikely before 1 year of age.) We discuss the classification systems and specific issues that hand surgeons want to know from the radiologists.

Concurrent dorsal dimelia in 160 consecutive patients with congenital anomalies of the hands and feet

This study was designed to investigate the prevalence of dorsal dimelia in a series of 160 consecutive patients with congenital anomalies of the hands and feet, and to investigate the distribution of dorsal dimelia and the concurrent anomalies. Five cases (3.1%) showed evidence of dorsal dimelia and the distribution of dorsal dimelia was similar to the distribution of concurrent anomalies in all five cases. Another 11 cases of concurrent dorsal dimelia with other congenital anomalies have been reported previously with a positive match in the distributions in all cases. This similarity in the distribution in all 16 reported cases (including the five cases in the current study) is statistically significant. It is concluded that dorsal dimelia in humans is not as rare as it is generally thought to be, and that it may be viewed as an error of dorso-ventral patterning, which occurs in the same distribution as other concurrent anomalies.