Thumb Hypoplasia Occurring in Patients With Preaxial Polydactyly
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Published on: May 26, 2023
Andrea S Bauer1, Anuj P Netto2, Michelle A James3
1Department of Orthopaedic Surgery, Boston Children's Hospital, Boston, MA.
Insights
Preaxial polydactyly can coexist with unrecognized thumb hypoplasia in children. This study found 8.2% of patients with preaxial polydactyly also had ipsilateral thumb hypoplasia, often diagnosed post-surgery.
Area of Science:
- Hand surgery
- Pediatric orthopedics
- Congenital hand anomalies
Background:
- Thumb polydactyly and thumb hypoplasia are typically considered distinct conditions.
- Case reports suggest a potential association between thumb polydactyly and ipsilateral thumb/radius hypoplasia.
- Embryologic understanding of upper limb development may explain this association.
Purpose of the Study:
- To test the hypothesis that preaxial polydactyly can present with unrecognized ipsilateral thumb hypoplasia.
- To determine the incidence of concurrent thumb hypoplasia in patients with preaxial polydactyly.
- To identify when thumb hypoplasia is diagnosed relative to polydactyly surgery.
Main Methods:
- Retrospective review of surgical database for preaxial polydactyly cases (2002-2014).
- Analysis of medical records for demographics, surgical procedures, and follow-up.
- Radiographic review to identify ipsilateral thumb hypoplasia and diagnostic timing.
Main Results:
- 132 patients with thumb polydactyly were reviewed.
- 8.2% (10 patients) showed evidence of ipsilateral thumb hypoplasia.
- Thumb hypoplasia was diagnosed pre-operatively in only 3 of the 10 affected patients.
Conclusions:
- The study supports the hypothesis that ipsilateral thumb hypoplasia can be present but unrecognized in children with preaxial polydactyly.
- A significant percentage (8%) of patients with preaxial polydactyly may have concurrent thumb hypoplasia.
- Early recognition of thumb hypoplasia may be challenging and often occurs post-operatively.
Purpose:
Thumb polydactyly and thumb hypoplasia are generally regarded as separate clinical entities. However, several case reports indicate that hypoplasia of both the thumb and the radius can occur in patients with thumb polydactyly and improved understanding of the genetics of the developing upper limb may give an embryologic explanation for this occurrence. Our hypothesis was that patients with preaxial polydactyly can have ipsilateral thumb hypoplasia that may not be recognized until after surgical reconstruction of the extra digit.
Methods:
We searched our surgical database for all procedures performed on patients with a diagnosis of preaxial polydactyly between 2002 and 2014. We reviewed the medical record for demographic data, surgical procedures, and follow-up information. In addition, all available radiographs were reviewed. Through this, we identified patients with a diagnosis of ipsilateral thumb hypoplasia, including when in the course of treatment the diagnosis was made, and any related subsequent procedures.
Results:
We reviewed 132 patients who underwent reconstruction of thumb polydactyly, 10 of whom were identified as having evidence of ipsilateral thumb hypoplasia, an incidence of 8.2%. The diagnosis of thumb hypoplasia was made before surgery in 3 of the 10 patients. One additional patient was noted to have a duplicate thumb on one side and a hypoplastic thumb on the contralateral side.
Conclusions:
This study supports the hypothesis that children with preaxial polydactyly can have ipsilateral thumb hypoplasia that may not be noted before surgery. In this study group, 8% of patients with preaxial polydactyly had ipsilateral hypoplasia.
Type Of Study/Level Of Evidence:
Prognostic IV.
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