Thumb Hypoplasia

Author: Mark Karadsheh

Topic updated on 05/06/13 4:51pm

Introduction

Congenital underdevelopment of the thumb frequently associated with partial or complete absence of the radius
Epidemiology
- incidence
  - 1/100,000 live births
- demographics
  - male = female
- location
  - bilateral involvement in ~60% of patients
  - right hand more common than left
Pathophysiology
- exact cause during embryologic development has yet to be elucidated
Associated anomalies
- greater than 80% of patients will have associated anomalies including
  - VACTERL
  - Holt-Oram
  - thrombocytopenia-absent radius (TAR)
  - Fanconi anemia

Classification & Treatment

Treatment algorithm depends on presence of carpometacarpal joint stability

Blauth Classification
Type	Description	Treatment
Type I	Minor hypoplasia All musculoskeletal and neurovascular components of the digit are present, just small in size	No surgical treatment required
Type II	All of the osseous structures are present (may be small) MCP joint ulnar collateral ligament instability Thenar hypoplasia	Stabilization of MCP joint Release of first web space Opponensplasty
Type IIIA	Musculotendinous and osseous deficiencies CMC joint intact Absence of active motion at the MCP or IP joint
Type IIIB	Musculotendinous and osseous deficiencies. Basal metacarpal aplasia with deficient CMC joint Absence of active motion at the MCP or IP joint.	Thumb amputation & pollicization
Type IV	Floating thumb Attachment to the hand by the skin and digital neurovascular structures
Type V	Complete absence of the thumb

Presentation

Physical exam
- inspection
  - extrinsic tendon abnormalities
    - pollex abductus
      - flexor pollicus longus attaches to normal insertion and the extensor tendon
    - hypoplasia of thenar musculature
  - absence of skin creases indicates muscle or tendon abnormalities
  - excessive abduction of MCP joint
- range of motion and instability
  - ulnar collateral ligament laxity
  - web-space tightness
- evaluation for associated anomalies is essential
  - cardiac
    - auscultation
    - echocardiography
  - kidneys
    - ultrasound
  - abdomen
    - ultrasound

Imaging

Radiographs
- recommended views
  - bilateral films of hand, wrist and forearm

Studies

Labs
- peripheral blood smear and complete blood count
  - important to rule out Fanconi anemia
Additional studies
- chromosomal challenge test
  - detects Fanconi anemia before bone marrow failure

Treatment

Nonoperative
- observation
  - indications
    - Type I hypoplasia where augmentation of thenar musculature (thumb abduction) is not necessary
Operative
- opposition tendon transfer (opponensplasty)
  - indications
    - Type I hypoplasia with insufficient thumb abduction
- release of first web space, opposition transfer, stabilization of MCP joint
  - indications
    - Type II and IIIA hypoplasia
- pollicization
  - indications
    - Type IIIB, IV, V hypoplasia

Surgical Techniques

Opponensplasty (opposition transfer)
- technique
  - performed using
    - flexor digitorum superficialis or
    - abductor digiti minimi
First web space deepening
- technique
  - usually performed with Z-plasty
Stabilization of MCP joint
- technique
  - three options
    - fusion
    - reconstruction of UCL with FDS
    - reconstruction of UCL with free tendon graft
Pollicization
- technique
  - plan skin incision to avoid skin grafts
  - isolate index finger on its neurovascular bundles
  - detach first dorsal and palmar interosseous muscles
  - shorten digit by removing index finger metacarpal and epiphyseal plate
  - stabilize index MCP joint
  - reattach and balance musculotendinous units
  - reconstruct long extensor tendons
  - rebalance flexor tendons

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Qbank (3 Questions)

TAG

(OBQ10.6) The parents of a newly adopted 3-year-old boy bring the child to the office for evaluation of his thumb. A clinical photograph is provided in figure A. Which of the following is the most important factor in determining thumb reconstruction versus ablation and pollicization? Topic

Review Topic

FIGURES: A

1. Stability of the carpometacarpal joint
2. Functional ROM of the wrist
3. Functional ROM of the index, middle, ring, and small fingers
4. Skin contracture of the first web space
5. Absence of a thumb interphalangeal joint

PREFERRED RESPONSE ▶

DISCUSSION: The clinical photograph demonstrates a hypoplastic thumb. The incidence of thumb hypoplasia is 1 in every 100,000 births and associated anomalies including radial aplasia, thrombocytopenia, and renal/cardiovascular/CNS anomalies are frequent. Stability of the carpometacarpal joint is essential for success of thumb reconstruction procedures. If CMC stability is deficient, then ablation and pollicization is preferred.

Light et al describe the evaluation and surgical technique involved in treating the hypoplastic thumb. They note that severe thumb hypoplasia and aplasia are best treated by thumb ablation and pollicization of the index finger.

REFERENCES:

1. Light TR, Gaffey JL. Reconstruction of the hypoplastic thumb. J Hand Surg Am. 2010 Mar;35(3):474-9. PMID:20138713 (Link to Abstract)

2. Waters PM, Mih AD. Forearm, wrist, and hand: pediatrics. In: Vaccaro AR. Orthopaedic Knowledge Update 8. Rosemont, IL: American Academy of Orthopaedic Surgeons; 2005:715-726.

Question Authors:

John Badylak MD, Michael Hughes MD, Ben Taylor MD,

Please Rate Educational Value!

3.0

Average 3.0 of 12 Ratings

TAG

(OBQ05.256) What is the most important variable when determining treatment of a hypoplastic thumb? Topic

Review Topic

1. contralateral thumb function
2. thenar muscle function
3. presence of an extensor pollicis longus tendon
4. carpometacarpal joint stability
5. metacarpophalangeal joint stability

PREFERRED RESPONSE ▶

DISCUSSION: Congenital thumb hypoplasia presents as a wide range of first ray deficiencies and frequently occur as part of a larger systemic syndrome such as Holt-Oram, Fanconi’s, or Apert’s syndrome. To function correctly, the thumb must be positioned so that it can oppose the adjacent medial fingers and grasp objects securely from an antiposed (abducted, slightly extended, and pronated) position. Although normal motion is usually not required at the MP or interphalangeal joints, thumb function is greatly dependent on preserving a full arc of circumduction at the carpometacarpal (CMC) joint. The CMC joint must be sufficiently stable to provide resistance during grasp and pinch. The Blauth's classification ranges from type I to V and Types IIIB to V are treated with pollicization. The key difference between a Blauth IIIA and IIIB is the presence of carpometacarpal joint stability in Blauth IIIA.

REFERENCES:

1. Trumble TE: Hand Surgery Update 3: Hand, Elbow, & Shoulder, Rosemont, IL, American Society for Surgery of the Hand, 2003, pp 599-624

2. Kleinman WB, Strickland JW. Thumb Reconstruction. Green DP, Hotchkiss RN, Pederson WC (eds.): Green’s Operative Hand Surgery, ed. 4. Philadelphia, PA, Churchill Livingstone; 1999: 2068-170

3. Blauth W. [The hypoplastic thumb]. Arch Orthop Unfallchir. 1967;62(3):225-46. PMID:4874597 (Link to Abstract)

Question Authors:

Derek Moore,

Please Rate Educational Value!

3.0

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TAG

(OBQ04.120) Using the Blauth classification of thumb hypoplasia, grade IIIA can be treated with thumb reconstruction whereas grade IIIB is treated with thumb amputation & pollicization. What is the key difference between these two grades? Topic

Review Topic

1. presence of complete osseous structures
2. presence of intact musculotendinous structures
3. carpometacarpal joint stability
4. metacarpophalangeal joint stability
5. presence of an extensor pollicis longus tendon

PREFERRED RESPONSE ▶

DISCUSSION: To function correctly, the thumb must be positioned so that it can oppose the adjacent medial fingers and grasp objects securely from an antiposed (abducted, slightly extended, and pronated) position. Although normal motion is usually not required at the MP or interphalangeal joints, thumb function is greatly dependent on preserving a full arc of circumduction at the carpometacarpal (CMC) joint. The CMC joint must be sufficiently stable to provide resistance during grasp and pinch. The Blauth's classification ranges from type I to V and Types IIIB to V are treated with pollicization. The key difference between a Blauth IIIA and IIIB is the presence of carpometacarpal joint stability in Blauth IIIA.

REFERENCES:

1. Kleinman WB, Strickland JW. Thumb Reconstruction. Green DP, Hotchkiss RN, Pederson WC (eds.): Green’s Operative Hand Surgery, ed. 4. Philadelphia, PA, Churchill Livingstone; 1999: 2068-170

2. Blauth W. [The hypoplastic thumb]. Arch Orthop Unfallchir. 1967;62(3):225-46. PMID:4874597 (Link to Abstract)

Question Authors:

Paul D. Kim MD, Derek Moore,

Please Rate Educational Value!

4.0

Average 4.0 of 11 Ratings

Groups

ABOS II: Thumb Hypoplasia

General - Oral Boards Review

7/29/2011

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Evidence & References Show References

Level of Evidence 5 and Other Journal Articles (includes Case Reports, Expert Opinions, Personal Observations, and Biomechanic Studies)

Light TR, Gaffey JL. Reconstruction of the hypoplastic thumb. J Hand Surg Am. 2010 Mar;35(3):474-9. PMID:20138713 (Link to Abstract)

Textbooks

Review of Orthopaedics, 6th Edition, Mark D. Miller MD, Stephen R. Thompson MBBS MEd FRCSC, Jennifer Hart MPAS PA-C ATC, an imprint of Elsevier, Philadelphia, Copyright 2012
AAOS Comprehensive Orthopaedic Review, Jay R. Leiberman. Published by American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2009
Orthopaedic Knowledge Update 10, John M Flyn. Published by American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2011
Hoppenfeld SP. Surgical Exposures in Orthopaedics: The Anatomic Approach. Lipponcott, Williams, and Wilkins, Philadelphia, PA, Copyright 2009
Orthopaedic In-training Examination (OITE) Questions 2004-2012, American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2004-2012
Self-Assessment Examination (SAE) Questions 2004-2012, American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2004-2012
Waters PM, Mih AD. Forearm, wrist, and hand: pediatrics. In: Vaccaro AR. Orthopaedic Knowledge Update 8. Rosemont, IL: American Academy of Orthopaedic Surgeons; 2005:715-726.

Undefined

Trumble TE: Hand Surgery Update 3: Hand, Elbow, & Shoulder, Rosemont, IL, American Society for Surgery of the Hand, 2003, pp 599-624
Kleinman WB, Strickland JW. Thumb Reconstruction. Green DP, Hotchkiss RN, Pederson WC (eds.): Green’s Operative Hand Surgery, ed. 4. Philadelphia, PA, Churchill Livingstone; 1999: 2068-170
Blauth W. [The hypoplastic thumb]. Arch Orthop Unfallchir. 1967;62(3):225-46. PMID:4874597 (Link to Abstract)
Kleinman WB, Strickland JW. Thumb Reconstruction. Green DP, Hotchkiss RN, Pederson WC (eds.): Green’s Operative Hand Surgery, ed. 4. Philadelphia, PA, Churchill Livingstone; 1999: 2068-170
Blauth W. [The hypoplastic thumb]. Arch Orthop Unfallchir. 1967;62(3):225-46. PMID:4874597 (Link to Abstract)

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Thumb Hypoplasia

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