On-Top Osteotomy of the Phalanx Base Combined With Modified Bilhaut: Cloquet Procedure for Atypical Radial Polydactyly

In this report, we present the combination of on-top plasty with a modified Bilhaut-Cloquet procedure for treating atypical radial polydactyly with duplication at the metacarpophalangeal (MP) joint and triphalangism of the radial and ulnar phalanges, hypoplastic middle phalanx of the radial thumb, and hypoplastic phalanx base of the ulnar thumb. To preserve the stable MP and interphalangeal joints of the radial and ulnar thumbs, respectively, on-top plasty involved osteotomizing the middle phalanx and transferring the distal end of the middle phalanx of the ulnar finger to the phalanx base of the radial thumb. A modified Bilhaut-Cloquet procedure was used to combine the tips and nails of both thumbs. Twelve months postoperatively, good joint alignment and thumb tip appearance were achieved. On-top plasties effectively combined the desirable parts of both thumbs. The modified Bilhaut-Cloquet technique is particularly well-suited for atypical cases, such as the present case.

A large, ten-generation family with autosomal dominant preaxial polydactyly/triphalangeal thumb: Historical, clinical, genealogical, and molecular studies

We present a large, ten-generation family of 273 individuals with 84 people having preaxial polydactyly/triphalangeal thumb due to a pathogenic variant in the zone of polarizing activity regulatory sequence (ZRS) within the exon 5 of LMBR1. The causative change maps to position 396 of the ZRS, located at position c.423 + 4909C > T (chr7:156791480; hg38; LMBR1 ENST00000353442.10; rs606231153 NG_009240.2) in the intron 5 of LMBR1. The first affected individual with the disorder was traced back to mid-1700, when some settlers and workers established in Cervera de Buitrago, a small village about 82 km North to Madrid. Clinical and radiological studies of most of the affected members have been performed for 42 years (follow-up of the family by LFGA). Molecular studies have confirmed a pathogenic variant in the ZRS that segregates in this family. To the best of our knowledge, this is the largest family with preaxial polydactyly/triphalangeal thumb reported so far.

Clinical Characteristics and Surgical Outcomes of Congenital Ulnar-deviated Thumbs: Delta Triphalangeal Thumbs and Irregular Epiphyses

BACKGROUND

Delta triphalangeal thumbs (DTPT) and irregular epiphysis thumbs (IET) had different anatomic deformities. Our primary purpose was to evaluate the clinical and radiographic outcomes of surgical treatment in DTPT and IET.

METHODS

In total, 43 ulnar-deviated thumbs were included and categorized into 2 types according to x-ray and exploration during surgery, DTPT and IET. Surgical excision of the delta phalanx in DTPT and intraepiphysis osteotomy in IET was conducted.

RESULTS

In total, 23 ulnar-deviated thumbs were classified as DTPT and 20 as IET. Ten thumbs that could not be classified initially were followed-up until they could be categorized at the mean age of 24 months. The preoperative mean degrees of ulnar deviation at the interphalangeal joints were 40 and 33 degrees, in DTPT and IET, respectively. The mean degrees were 2 and 5 degrees in final follow-up, showing significant improvement (DTPT, P<0.05; IET, P<0.05). Complications during the study included residual ulnar deviation, overcorrection, and nonunion. The stability and range of movement at the interphalangeal joint were good overall. According to the Japanese Society for Surgery of the Hand scoring system, results were excellent in 29 cases, good in 13, and fair in 1.

CONCLUSIONS

Ulnar clinodactyly of the thumb occurs because of different anatomic features such as DTPT or IET. We recommend surgical treatment be postponed until the anatomic abnormality can be ascertained. Furthermore, almost all patients with ulnar-deviated thumbs had significant improvement in clinical and radiographic outcomes after surgery.

Normal and five-fingered hand: comparative X-ray morphometry in the post-natal age

BACKGROUND

Five-fingered hand (5-FH) with completely developed phalanges is a rare phenotype observed so far only in humans and characterised by three phalanges of the 1st ray. A long-lasting, debated question is if the missing element of the normal hand 1st ray is the metacarpal or the phalanx. In this study, comparative X-rays morphometry of long bones in normal and 5-FH is carried out with the aim to face this question through homology analysis of long bone segments in the transverse and longitudinal line of normal hand and 5-FH.

MATERIALS AND METHODS

In the normal hand X-rays (n =20) and in a 5-FH X-rays series (n = 9) the relative length of each segment on the ray total length and the index of growth rate (IGR) were assessed. The calculation of the first parameter in normal hand bi-phalangeal thumb was carried out on the 3rd ray total length in the same hand.

RESULTS

The parameters of relative length and the proximal/distal growth rate asymmetry in the post-natal period (assessed through the IGR) confirmed in 5-FH the homology of all the five segment on the transverse line. In the normal control hand, the relative length assessment methodology was biased by the missing segment of the thumb, therefore, the reference to the 3rd ray total length in the same hand (instead of the 1st), allowed the homology analysis of the thumb metacarpal and 1st phalanx with the lateral segments (2nd-5th ray) of the same hand. The 5-FH analysis was used to choose the more appropriate reference ray for the normal hand group.

CONCLUSIONS

The comparative analysis of relative lengths and IGRs in the two groups suggested homology of the (anatomical) 1st metacarpal with the 2nd-5th proximal phalanges in the same hand and that of the (anatomical) 1st proximal phalanx with the 2nd-5th mid phalanges. These data suggest that the missing segment of the normal hand thumb is the metacarpal.

Analysis of Causes for Congenital Ulnar Deviated Thumbs at the Distal Phalanx Level in 157 Thumbs

PURPOSE

To investigate anatomic abnormalities causing a congenital ulnarly deviated thumb at the distal phalanx.

METHODS

A total of 122 children with 157 congenital ulnarly deviated thumbs at the distal phalanges were reviewed, including those with isolated deformity or polydactyly. We analyzed the incidence and characteristics of the underlying anatomic abnormalities as well as the differential diagnoses.

RESULTS

Three main causes of an ulnarly deviated thumb were observed. Abnormal hypertrophic epiphyses were found in 96 thumbs. An extra phalanx lying between the normal proximal and distal phalanges was found in 59 thumbs. A previously undescribed cause was found in 2 thumbs with Wassell IV polydactyly, in which an obliquely angled articular surface of the proximal phalanx manifested with ulnar deviation at the interphalangeal joint. Radiographic analysis showed that in cases with abnormal epiphyses, the epiphysis was in good apposition and good alignment with its relevant distal phalanx; the distance from the abnormal epiphysis to the phalanx was usually less than 1 mm. In contrast, in cases of extra phalanges, the distance from the epiphysis to the phalanx averaged more than 2 mm and there was poor apposition between the distal phalanx and the extra bone.

CONCLUSIONS

Abnormal hypertrophic epiphysis and triphalangeal thumb are the 2 main causes of a congenital ulnarly deviated thumb. A distance of more than 2 mm between the abnormal bone and the distal phalanx suggests a triphalangeal thumb.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Homozygous noncanonical splice variant in LSM1 in two siblings with multiple congenital anomalies and global developmental delay

Two siblings, one male and one female, ages 6 and 13 yr old, have similar clinical features of global developmental delay, multiple congenital anomalies affecting the cardiac, genitourinary, and skeletal systems, and abnormal eye movements. Whole-genome sequencing revealed a homozygous splice variant (NM_014462.3:c.231+4A>C) in LSM1 that segregated with the phenotype in the family. LSM1 has a role in pre-mRNA splicing and degradation. Expression studies revealed absence of expression of the canonical isoform in the affected individuals. The Lsm1 knockout mice have a partially overlapping phenotype that affects the brain, heart, and eye. To our knowledge, LSM1 has not been associated with any human disorder; however, the tissue expression pattern, gene constraint, and the similarity of the phenotype in our patients and the knockout mice models suggest it has a role in the development of multiple organ systems in humans.

Triphalangeal thumb: clinical features and treatment

Triphalangeal thumb is a rare congenital anomaly in which the thumb has three phalanges. Clinical presentation of triphalangeal thumb can vary considerably and can be present in both hands or unilateral. The thumb can be long with a finger-like appearance. The presence of clinodactyly depends on the shape of the extra phalanx varying from wedge-shaped to rectangular. Various joints, ligaments, muscles, and tendons of the first ray can be hypoplastic or absent, with varying degrees of stiffness or instability. The aim of surgical treatment is to reconstruct or correct the anatomic anomalies to obtain greater function and a more acceptable appearance. In our series, operations varied from removal of the delta phalanx with ligament reconstruction to multiple osteotomies and rebalancing of soft tissues. Results in these often complex cases can be rewarding if the surgeon has sufficient knowledge of the underlying anatomic differences. This review summarizes our current concepts of presentation and management of the triphalangeal thumb.

A novel mutation (g.106737G>T) in zone of polarizing activity regulatory sequence (ZRS) causes variable limb phenotypes in Werner mesomelia

Werner mesomelia is characterized by a sequence variation in the specific region (position 404) of the enhancer ZRS of SHH. The phenotype comprises variable mesomelia, abnormalities of the thumb and great toe and supernumerary digits. We describe extensive variation in limb phenotype in a large family and report on a novel sequence variation NG_009240.1: g.106737G>T (traditional nomenclature: ZRS404G>T) in the ZRS within the LMBR1 gene. The newly recognized clinical features in this family include small thenar eminence, sandal gap, broad first metatarsals, mesoaxial polydactyly, and postaxial polydactyly. We provide information on 12 affected family members. We review the literature on how a sequence variation in ZRS may cause such diverse phenotypes.

Bilaterally cleft lip and bilateral thumb polydactyly with triphalangeal component in a patient with two de novo deletions of HSA 4q32 and 4q34 involving PDGFC, GRIA2, and FBXO8 genes

We report on a newborn boy with a bilateral cleft of the primary palate, duplicated triphalangeal thumbs, and a patent foramen ovale. During childhood he had moderate developmental delay. Brain MRI at 4 years was normal. The concurrence of non-syndromic clefts of the lip/palate (CL/P) and duplicated thumbs with triphalangeal component has, to our knowledge, not been reported so far. In our case, array-CGH analysis documented two de novo deletions (∼1.2 Mb and ∼400 Kb) of the long arm of chromosome 4, containing four genes: platelet-derived growth factor C (PDGFC), glycine receptor beta subunit (GLRB), glutamate receptor ionotropic AMPA2 (GRIA2), and F-box protein 8 gene (FBXO8). PDGFC codes for a mesenchymal cell growth factor already known to be associated with clefts of the lip. Pdgfc(-/-) mice have skeletal anomalies, and facial schisis resembling human cleft/lip palate. GRIA2 codes for a ligand-activated cation channel that mediates the fast component of postsynaptic excitatory currents in neurons, and may be linked to cognitive dysfunction. FBXO8, a gene of unknown function, is a member of the F-box gene family, among which FBXW4, within the minimal duplicated region associated with human split-hand/foot malformation type 3 (SHFM type 3). The presence of overlapping deletions in patients who do not share the same phenotype of our case suggests incomplete penetrance, and a possible effect of modifier genetic factors.