Epidemiological statistics of congenital thumb duplication in the Chinese population

Background Thumb duplication is a very common congenital malformation. This study describes and compares the phenotypic manifestations of polydactyly between southwest and northeast China. However, previous studies had a limited sample size. Therefore, this study used a large sample. Methods A total of 3549 well-characterized thumb duplication cases were divided into group A (southwest China) and group B (northeast China). Results In group A and group B, the left-to-right ratio was 1:1.5 and 1:1.75, respectively, and the female-to-male ratio was 1:1.5 and 1:1.58, respectively. Conclusions There were no significant differences in gender distribution or the distribution of left and right polydactyly between the two groups, but the distribution of bilateral polydactyly was significantly different.

Modified method for reconstruction of thumb abduction function in children undergoing surgical treatment of thumb duplication

Purpose This study was performed to evaluate a modified method of reconstructing the thumb abduction function in children undergoing surgical treatment of thumb duplication. Methods This retrospective study included 33 children (38 thumbs) with Wassel type III to VII thumb duplication who underwent excision of the polydactylism and osteotomy of the preserved thumb. Among them, 16 children (19 thumbs) underwent reconstruction of the attachment of the articular capsule and collateral ligament of the metacarpophalangeal joint, abductor pollicis brevis and flexor pollicis brevis by the anchor technique (Group A), while 17 children (19 thumbs) underwent suturing the attachment of the above-mentioned soft tissues to the periosteum (Group B). All children were followed up for six years after surgery. The appearance, function and joint stability of the preserved thumb were compared between the two groups; the bone alignment and development were observed. Results The deformity rate of preserved thumbs and the positive rate of lateral stress test were significantly lower in Group A than B (p < 0.05). The modified Tada score and the distance of first web were significantly higher in Group A than B (p < 0.05). Flexion, extension, adduction, abduction and palmar movement of the thumbs were good; bone alignment and development were good and no osteophyte or anchor shadow was left in the preserved thumbs in Group A. Conclusion Reconstruction of the abduction function using the anchor technique is effective in children undergoing surgical treatment for Wassel type III to VII thumb duplication and it may be superior to the conventional technique. Level of evidence III

Long-term outcomes after corrective cartilaginous joint resection based on arthrographic findings of duplicated thumbs

We report greater than 10-year outcomes in duplicated thumbs following corrective cartilaginous resection during the growth period. We have undertaken corrective resection of cartilaginous joint connections based on intraoperative arthrographic findings to reconstruct favourable alignment in six Wassel Type II and IV thumb duplication in six patients. The age at surgery was 13 months (range 10–15), and the average post-surgical follow-up was 134 months (range 120–160). We observed five excellent and one good outcome using the Japanese Society for Surgery of the Hand scoring method. Favourable joint congruency and alignment were preserved, and no growth plate arrest or joint space narrowing was present more than 10 years after surgery. We conclude that corrective resection of the cartilaginous joint based on intraoperative arthrographic findings has long-term reliability for duplicated thumbs, especially those of Wassel Type II and IV, which have a cartilaginous joint connection. Levels of evidence: IV

Thumb duplication/polydactyly

A significant lesson for those assessing the work of others stems from the necessity to review what has been written before. It remains a common but human error to misinterpret or misrepresent the words of others and indeed, for inconsistencies in these to become apparent. This is certainly so in the field of congenital hand surgery and especially so with discussion of thumb duplication/polydactyly. Many of the presentations in this journal issue deal with the subject of thumb duplication. All involve a consideration of classification despite an emphasis on investigative measures and techniques in some. For ease of reading, I will place my comments on these articles within the categories of classification, investigations assisting management decisions and alternative techniques, though the contents of each article are not necessarily restricted to these categories.

Correction of Thumb Duplication: A Systematic Review of Surgical Techniques

Surgical intervention for thumb duplication can be divided into three categories: simple excision of the accessory thumb, excision of the accessory thumb with reconstruction from available “spare parts,” and combining the two thumbs into one, as described by Bilhaut. This prospectively PROSPERO registered systematic review evaluates the overall, aesthetic and functional outcomes for the latter two options (reconstruction from spare parts vs. combining two thumbs into one), aiming to facilitate evidence-based decision making when addressing thumb duplication and direct future research. The review was performed in accordance with the Cochrane Handbook of Systematic Reviews and PRISMA statement. Embase, PubMed, Medline, and Cochrane databases were systematically searched. Studies offering comparisons of techniques were included. Risk of bias was assessed using the Risk of Bias In Non-randomized Studies—of Intervention tool. The quality of the evidence was assessed using the Grading of Recommendations, Assessment, Development, and Evaluation. Ten retrospective observational studies were included. Data did not consistently allow analysis by procedure type. Four studies reported similar overall outcomes between techniques, while two specifically reported poor overall outcomes for the Bilhaut procedure. Two studies reported comparatively worse aesthetic outcomes for the Bilhaut procedure with four studies reporting comparatively improved functional outcomes for this procedure. Overall, interpretation of outcomes was challenging with no patient-reported outcome measures used. The quality of the evidence was universally “very low” due to all studies being at risk of methodological bias. Based on the available evidence, surgical techniques for thumb duplication correction appear comparable regarding overall outcome. There is limited evidence suggesting reconstruction with spare parts offers superior aesthetic outcomes at the expense of stability. The level of evidence is III.

Opening wedge phalangeal osteotomy for correction of Wassel type IV-D thumb duplication

Background Thumb duplication is one of common anomalies of the hand. Among of Wassel type IV subtypes, type IV-D duplication with a zigzag deformity is most challenging for reconstructing. Several factors may affect the surgical outcomes. This study aimed to present an opening wedge osteotomy at proximal phalangeal neck for treating type IV-D duplication. Methods Data from 14 patients are presented in this study. Eight patients had duplication of the right thumb, and six left thumb. After removal of radial supernumerary thumb, a snug collateral ligament was repaired to correct angular deformity of metacarpophalangeal joint (MCP). Angular deformity of the interphalangeal (IP) joint was corrected by an opening wedge osteotomy at the proximal phalangeal neck. A wedge bone from ablated thumb was grafted to correct the malalignment. IP joint was further stabilized by plication of the ulnar capsule. The relocation of radial part of FPL to the center of distal phalangeal base by use of pull-out suture technique Results After surgery, the angulations of the IP joints and the MCP joints were improved. Bone union was observed in all patients. According to the Japanese Society for Surgery of the Hand evaluation form, twelve cases were rated good, 2 cases fair. Stability of IP and MCP joints was good in all cases. The active ROM of IP was less in residual thumb than in normal thumb. Small nails were observed in some patients. Conclusions Although the reconstructed thumbs were smaller than normal counterparts, they were aligned and with stable joints. The opening wedge osteotomy at proximal phalangeal neck could improve realignment of IP joint and prevent reoccurrence of deformity over time.