Triphalangeal Thumbs in the Pediatric Population: Long Term Outcomes Following Surgical Intervention
Condition: Phalanx of Supernumerary Digit of Hand
MeSH terms: Polydactyly
Study type: Observational

Summary: 
      A triphalangeal thumb is a thumb with three phalanges. The thumb often appears long and
      fingerlike, and can sometimes be in the same plane as the other fingers. Anatomically, the
      extra phalanx can have different shapes. Several classification systems have been used, but
      the simplest and most often used is the Wood (1976) classification by the shape of the extra
      phalanx. If the extra phalanx is triangularly shaped it is classified as a type I. Type II
      has a rectangular shaped extra phalanx but it has not developed as a full phalanx. Type III
      is a full extra phalanx.
    

Detailed description: 
      A triphalangeal thumb is a thumb with three phalanges. The thumb often appears long and
      fingerlike, and can sometimes be in the same plane as the other fingers. Anatomically, the
      extra phalanx can have different shapes. Several classification systems have been used, but
      the simplest and most often used is the Wood (1976) classification by the shape of the extra
      phalanx. If the extra phalanx is triangularly shaped it is classified as a type I. Type II
      has a rectangular shaped extra phalanx but it has not developed as a full phalanx. Type III
      is a full extra phalanx.

      Different treatment strategies have been developed based on the type of triphalangeal thumb.
      This project looks specifically at type I, or a delta phalanx. The goals of surgery in any
      type are to reconstruct the anatomic deformity with a stable, functional thumb while
      providing an acceptable appearance.

      There is no consensus on how triphalangeal thumbs with a delta phalanx should be treated.
      Bunnell and Campbell in the 1940s advocated doing no surgery at all. Milch advocated excising
      the abnormal phalanx in the pediatric population but supporting non-operative treatment for
      the adult population. A potential unwanted result of excision has been an angulated joint.
      Buck-Gramcko proposed that excision of the delta phalanx combined with ligament
      reconstruction could give a better result than with excision alone.

      Hovius recommended different treatment based on the age of presentation. For patients less
      than 6 years, he advocated excision of a transverse oval piece of skin, resection of the
      extra phalanx with reconstruction of the radial collateral ligament at the new IP joint, and
      lengthening of the ulnar collateral ligament. For patients older than 6 years, he advocates
      partial resection of the extra phalanx with correction of the angle and arthrodesis of the
      DIP joint. Usually, collateral ligament reconstruction is not necessary in these cases.

      Horii et al reviewed 13 type I delta triphalangeal thumbs with no associated hand
      abnormalities. Surgical treatment for these patients consisted of excision of an accessory
      phalanx and the repair of the collateral ligament. The IP joint was temporarily fixed with
      Kirschner wires for 4-6 weeks. Mean follow-up was 8.9 years. All patients were satisfied with
      the improvement in appearance. The mean IP joint motion was 54 degrees. No patients
      complained of instability or pain in the IP joint. Only one patient had ten degrees of
      lateral bending. They recommend operating on these patients between ages 1-2 years, when the
      phalangeal epiphyses becomes clear. They felt that earlier excision allows for better joint
      adaptation. The children also will learn how to use their hands correctly.

      Recently it has been debated that it is beneficial to wait to operate on these children until
      they are older, and their bones and joints have matured. At that point, an osteotomy could be
      performed. Although these results have not been published yet, several well-respected hand
      surgeons have concluded that their outcomes have been better on patients who have had delayed
      surgery.

      In our institutions, children generally have their thumb reconstructed using a delta phalanx
      excision with repair of the ligament around 1 to 2 years.
    

Observational model: Cohort
Sampling method: Non-Probability Sample
Study population: 
        A search will be performed using CPT code 26587 (reconstruction of a supernumerary digit)
        at both Primary Children's Hospital and Shriners to identify all patients who Dr. Wang and
        Hutchinson operated on with a delta phalanx.
      
Keywords: delta phalanx; thumb reconstructed; triphalangeal thumbs