Treatment for Wassel Types V and VI Thumb Polydactyly

Abstract

Background: Polydactyly of the thumb is the most common congenital anomaly of the hand, but there have been few reports regarding Wassel types V and VI. The purpose of this study is to present our surgical strategies and outcomes for cases of Wassel types V and VI polydactyly of the thumb. Methods: Twenty-nine thumbs of 29 patients were included in this study; 17 cases were Wassel type V and 12 cases were type VI. Our strategies for initial surgery were appropriate tendon and muscle relocations. Opponensplasty with the abductor digiti minimi or the flexor digitorum superficialis and osteotomy were not performed in the initial surgery. We evaluated pinch motion ability and the number of additional surgical procedures. The first web space and radial instability of the metacarpophalangeal (MCP) joint were measured by radiography while the patient held a polystyrene foam cone. Results: Twenty-two patients were able to perform a pulp pinch. Narrowing of the first web defined as the angle between the first and second metacarpus (1–2 MCA) < 40° occurred in five cases. Radial instability of the MCP joint defined as the angle between the first metacarpus and thumb proximal phalanx (1 MPA) > 20° occurred in seven cases. Additional surgery was performed in seven cases (24%) to improve insufficient thumb opposition, radial instability of the MCP joint, and narrowing of the first web. Patients in all reoperation cases were able to perform a pulp pinch. Conclusions: Our strategies for initial surgery often had satisfactory outcomes, but careful follow-up observations and appropriate reoperation for cases with poor initial outcomes were more important.

Abductor pollicis brevis rerouting and first web deepening for clasped thumb deformity in arthrogryposis multiplex congenita

“…Second, our study did not provide information about patientoriented outcomes and functional evaluations. In our experience, it is difficult to measure these parameters using any method in infants or young children and we have focused on obtaining radiographic evaluations for the first web space using a polystyrene cone (Bessho et al, 2020;Takagi et al, 2012Takagi et al, , 2016. Third, we did not have a control group to compare the efficacy of the APB rerouting with other techniques, such extensor tendon reconstruction only.…”

Soft tissue abnormalities in Wassel Type VI radial polydactyly: a detailed anatomical study

“…Makino et al (2003) reported long-term follow-up of patients with Type V and Type VI radial polydactyly, where 60% of patients required revision surgery but 80% of these patients who underwent revision surgery did not have any functional improvement. Bessho et al (2020) reported short-term surgical outcomes of 12 patients with Type VI radial polydactyly; three of the five patients with MCP joint radial deviation and one out of seven patients without MCP joint radial deviation required revision surgery, including opponensplasty with stabilization on the ulnar side of the MCP joint or reuse of the transferred abductor pollicis brevis for joint stabilization. In our patients, the abductor pollicis brevis and superficial head of the flexor pollicis brevis were not long enough to reach the MCP joint.…”

“…Although adduction deformity of the ulnar duplicate in Type VI radial polydactyly has been described in the literature (Bessho et al., 2020; Ogino et al., 1996), its anatomical basis has not been well discussed. In normal thumb anatomy, muscles associated with first metacarpal abduction include the abductor pollicis longus tendon, abductor pollicis brevis and opponens pollicis (McFarlane, 1962).…”

“…Wassel VI radial polydactyly is relatively uncommon, characterized by complete duplication of the first metacarpal and accounting for 3–5% of all radial polydactyly phenotypes (Ogino et al., 1996; Zuidam et al., 2008). These radial polydactyly cases are commonly associated with a narrowed first web and ulnar instability of the metacarpophalangeal (MCP) joint of the ulnar duplicate (Bessho et al., 2020; Ogino et al., 1996). A combination of an abducted radial thumb and an adducted ulnar thumb results in a divergent appearance of the thumb duplications.…”

On-top plasty for atypical Wassel type VI thumb duplication: Timing and key points of surgery

“…Thumb duplication is one of the most common congenital hand deformities, characterized by diverse morphological changes [1,2]. The Wassel classi cation is frequently used based on the shape of duplication and X-ray ndings.…”