Congenital thumb duplication is estimated to occur between 0.08 and 7.6 times per 1,000 live births; however its cause is still undetermined. In this report, we present a case of Wassel type VI thumb polydactyly. clinical examination revealed an optimal functional position and an aesthetically pleasing shape of the ulnar thumb as well as a superior nail and pulp. However, preoperative X-ray indicated a well formed carpometacarpal joint of the radial thumb compared to an underdeveloped CMC joint of the ulnar thumb. Through surgical procedure we combined the best parts of both thumbs with on-top plasty to achieve the most optimal outcome. In conclusion, it is important to determine an adequate treatment strategy for a patient based on both clinical and radiological assessments.

Thumb duplication is one of the most challenging pediatric reconstructive hand surgeries. Wassel types II and IV are the most frequent, but also the most complex reconstructions as the duplication arises at the joint level. Ablation and reconstruction, the most widely used technique, aims at achieving a stable, well-aligned, mobile and esthetically acceptable thumb. The paucity of reliable surgical guidelines leads to high rates of suboptimal surgical outcomes. This review evaluated the various reconstruction techniques detailed in the literature and highlighted useful methods to prevent common secondary complications.
A comprehensive PubMed and Embase literature search was made. Inclusion criteria were Wassel type II and/or IV, pediatric patients, and primary or secondary surgeries. Exclusion criteria were Bilhaut-Cloquet reconstruction and its modifications. Techniques were screened, collected and analyzed for the following secondary complications: instability, axial deformity, and contour deformity.
Thirty-two articles met the inclusion criteria and were reviewed. Postoperative instability was prevented by tightening the joint capsule by plication, advancement of the volar plate, or reconstruction of the collateral ligaments using a periosteal flap or the double-breasting technique. Axial deformity was prevented by arthroplasty, shaving a triangular portion of the metacarpal head, centralization of eccentric tendons, pulley reconstruction using flexor pollicis longus, or corrective osteotomies of the phalangeal or metacarpal bones using the wedge or oblique techniques. Limited range of motion was prevented by first webspace Z-plasty, and soft-tissue contouring was addressed by planned skin incisions and soft-tissue augmentation. Preoperative, perioperative and postoperative considerations, including splinting, imaging and immobilization, were also described.
Despite the ongoing advances and abundant knowledge in reconstructive strategies for thumb duplication, there are few studies that reviewed and analyzed the various reported options. This review provides physicians and trainees with guidance in surgical planning to prevent common secondary complications. Further research should focus on the development of standardized assessment tools, enabling reliable prospective comparative studies on thumb duplication reconstruction.
IV.

We report the application and results of skin defect coverage using the free lateral great toe flap in revision surgery for residual postoperative deformities in Wassel-Flatt type IV-D thumb duplications. This retrospective study included five patients treated between June 2020 and September 2021 to correct angular deformity and repair the secondary skin defect. All the flaps survived. The patients were followed up for 8-12 months and all the reconstructed thumbs had a satisfactory appearance. The results of the Japanese Society for Surgery of the Hand scoring system were excellent in one patient, good in three patients and fair in one patient. The results of the Alignment, Ulnar and Radial stability, Range of motion and Aesthetical aspects (ALURRA) scoring system were good in four patients and moderate in one patient.Level of evidence: IV.

Radial polydactyly or thumb duplication is a relatively common congenital malformation of the hand, whereby the surgical techniques can be broadly divided into simple excisions, reconstructions and a Bilhaut-Cloquet procedure. The aim of this study was to identify the appropriate surgical procedures and to present the clinical outcomes that can be achieved. We performed a multicenter analysis of cases of radial polydactyly surgically treated with reconstruction or a Bilhaut-Cloquet procedure between 2015 and 2022. The clinical outcome was assessed using a modification of the Tada score. A total of 28 cases of 27 patients with radial polydactyly were included in the study. The most common Wassel type was type IV (13 cases), and the most common surgical procedure was reconstruction (24 cases). Our study validates an algorithm from the literature as a helpful tool for decision making in selecting a surgical technique for radial polydactyly, although individual surgical experience should also be considered.

Long-term follow-up after surgical correction of patients with radial polydactyly might reveal unexpected or undesired outcomes that are accentuated by growth. It should be stressed that assessment of outcomes differs considerably by the system used. Preoperative examination can elucidate the underlying pathological anatomy of these anomalies and consequently, these anatomical differences should be corrected as much as possible during the first operation to prevent worse outcomes at long-term follow-up. In various long-term studies, the reoperation rate was in the range of 7%-28%, with the most common reasons being deviation, instability, nail deformity and suboptimal appearance. Most unfavourable results occur during growth and are frequently revealed only at longer-term follow-up. Concentration of care to a few centres is advised since these malformations occur in small numbers and experienced surgeons tend to have better results. Consensus on the used assessment system and multicentred studies are essential in future to better understand how we can prevent reoperations.

To present a surgical technique of combining the on-top plasty with modified Bilhaut-Cloquet procedure for reconstructing a rare type of complicated radial polydactyly and evaluate the outcomes.
Fourteen complicated radial polydactyly in 13 patients were corrected by combining the on-top plasty with modified Bilhaut-Cloquet procedure. Osteotomies were performed as required, and the acral part of the ulnar thumb was transposed onto the proximal part of the radial thumb. The distal parts of the two thumbs were isolated as neurovascular pedicled composite tissue flaps, including part of the distal phalanx and nail bed, and were attached together in an extra-articular way. The tendons were rebalanced, and the nail bed was reconstructed. Objective and subjective outcomes were assessed.
The average follow-up time was 32.4 months (6-60 months). All reconstructed thumbs were rated as good in appearance and function. The mean Vancouver Scar Scale score was 1.3 (range 1-2) and the mean Wang-Gao score of the reconstructed thumbnail was 9.4 (range 8-11). The Tada score for the function of the reconstructed thumb was 5.5 (range 5-6). The main active range of motion (ROM) of the interphalangeal joint (IPJ) was 2.1-38.9°. All parents were satisfied with the outcomes.
Because of the diverse manifestations of thumb polydactyly, individualized surgical treatment is recommended, and careful preoperative planning should be made with the principle of combining the best parts of the two thumbs. By combining an on-top plasty with modified Bilhaut-Cloquet procedure, a satisfactory result can be achieved for treating complicated radial polydactyly.

Wassel type IV-D thumb duplication is the most complex form and anatomic reconstruction is difficult. The aim of this study was to create an aesthetically satisfactory anatomical reconstruction for Wassel type IV-D radial polydactyly thumbs using the modified Bilhaut-Cloquet procedure. Surgery was performed on 24 thumbs with Wassel type IV-D radial polydactyly. To align the joint surfaces, the proximal phalanxes were unequally joined, primarily on the ulnar, and the distal phalanx was either symmetrically joined or unequally joined via curvature osteotomy. The patients were followed up for 12-91 months. The interphalangeal joint remained stable in all cases. The average functional score was 13.5 points (maximum 14 points). The overall average cosmetic score was 3.3 (maximum 4 points). Our modification of the Bihaut-Cloquet procedure produced good functional results for patients with Wassel type IV-D radial polydactyly. This method is used to correct the alignment and to stabilize the interphalangeal joint in both hypoplastic thumbs.

Radial longitudinal deficiency (RLD) is commonly associated with thumb hypoplasia. The association between RLD and radial polydactyly (RP) is uncommon, but case reports or case series have been reported. We report our experience of managing patients with this association. A total of 97 patients with RLD were seen in our department, of which six were children with concomitant RLD and RP. Four children had both RLD and RP in the same limb; of them, three also had RLD in the contralateral limb. The mean age at presentation was 11.6 months. Awareness of this association alerts the clinician to look for RLD in the presence of RP and vice versa. This case series supports recent experimental and clinical evidence that RP and RLD may be part of the same developmental spectrum. Further studies may guide its inclusion as a possible new category in the Oberg-Manske-Tonkin (OMT) classification of congenital upper-limb anomalies.Level of evidence: IV.

We studied the pathological anatomical structures of atypical Wassel Type VI thumb duplication to provide a theoretical basis for surgical treatment. Forty-seven patients with atypical Wassel Type VI thumb duplication were treated. We found that some of cases had an ulnar thumb without an extensor tendon, or without a flexor tendon, or without both. All the ulnar metacarpal bones were abnormal to variable degrees. On-top-plasty is currently the best procedure for the treatment of this type of anomaly. Flexor tendon reconstruction is an important factor in functional reconstruction of the thumb, and keeping the pulley and sheath intact is a key step in flexor tendon reconstruction. Placing the on-top-plasty level at the distal end of the metacarpal or at the proximal phalanx depends on the presence of the flexor tendon. According to the condition of the flexor tendon, the atypical Wassel Type IV duplication can be divided into two types: the absent type and the intact type.Level of evidence: VI.

UNASSIGNED: This study aims to evaluate functional and esthetic outcomes of thumb duplication correction in pediatric age.
UNASSIGNED: Retrospective study including all pediatric patients with thumb duplication undergoing surgical treatment between 2012 and 2017. We analyzed demographic data, surgical technique, and surgical outcomes considering Tada, Horii, and Tien scores, according to the following parameters: active mobility of the metacarpophalangeal and interphalangeal joints, stability, alignment, and family\'s opinion about cosmetic and function of the thumb. The Wassel-Flatt classification was used to classify the duplicated thumbs.
UNASSIGNED: A total of 11 patients were included, predominantly male (ratio 1.8:1), with a median age at time of surgery of 19[10-26] months and a median follow-up time after surgery of 23 [3-63] months. The Wassel- Flatt type IV thumb was the most frequent (73%). The postoperative evaluation revealed that 82% of patients had good results in Tada score, 73% had good results in Horii score, and all patients showed good results in Tien score. We found a relation between lower age and fair postoperative alignment (P = .047) and between fair postoperative alignment and fair final Tada (P = .022), Horii (P = .006), and Tien (P = .009) scores.
UNASSIGNED: Excision and reconstruction procedures are good options in the treatment of thumb duplication providing good clinical results, with excellent parent satisfaction. Timing of surgery is important for favorable esthetic outcomes, while angular deformity is a determining factor that for postoperative dissatisfaction.