thumb deformity and hypoplasia

1. Thumb Hypoplasia
Ashraf Abdelaziz MD
Lecturer of orthopedic surgery
Hand and reconstructive surgery
Alzhraa University Hospital
Al-Azhar university
2014

2. Review
 Introduction
 Classification
 Clinical Examination
 Management

3. Introduction
 Congenital thumb hypoplasia
frequently associated with partial or
complete absence of the radius
 Epidemiology
◦ 4.6% of congenital deformities consist of
thumb hypoplasia
◦ 1/100,000 live births
 Male = female

4.  Bilateral involvement in 60% of patients
 The right thumb is more affected
 Associated anomalies
◦ > 80% of patients have
associated anomalies including;
 VACTERL syndrome
 Holt-Oram syndrome
 Thrombocytopenia absent radius (TAR)
 Fanconi anemia

5. Classification
(modified)Blauth classification 1967
I Minimal shortening and narrowing
II
Web space narrowing
Hypoplastic intrinsic thenar muscles
MCP joint instability
A: uniaxial B: Multiaxial
III
A
Type II +extrinsic tendon abnormalities,
Hypoplastic metacarpal , and stable
carpometacarpal
B
Type II + extrinsic tendon abnormalities, Partial
metacarpal aplasia , and unstable
carpometacarpal
IV Floating thumb
V Absent thumb

7.  Buck-Gramcko incorporated soft-tissue
abnormalities in his classification of thumb
hypoplasia.
 Lister subdivided Blauth grade II into IIA
and IIB, based on the stability of the MCP
joint; uniaxial or multiaxial.
 The importance of Lister’s modification is
that with grade IIA, the MCP joint can be
reconstructed,

8.  The most common type of thumb hypoplasia is type V
 Buck-Gramcko modification of the Blauth classification
Hand Clin 1990

9.  Type III B

10.  Type III B

11.  Type IV

12. Clinical examination
 Careful upper limb examination
 Passive motion of all joints.
 Assessment of laxity of the collateral ligaments
of the interphalangeal (IP) joint and MCP .

13.  Inspection
 Extrinsic tendon abnormalities
 Hypoplasia of thenar musculature
 Absence of skin creases indicate 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.

14.  Radiographs
◦ recommended views
 bilateral films of hand, wrist and forearm

15. Studies
 Labs
◦ Peripheral blood smear and CBC
 important to rule out Fanconi anemia
 Additional studies
◦ Chromosomal challenge test
 detects Fanconi anemia before bone marrow failure

16. Treatment
 Nonoperative
◦ Observation
 Type I thumb hypoplasia.
 Operative Management of the hypoplastic
thumb is determined by the grade of thumb
hypoplasia.

17.  Opposition tendon transfer (Opponensplasty)
 Type I hypoplasia with insufficient thumb abduction
 Release of first web space, Opponensplasty,
and Stabilization of MCP joint
Type II and IIIA hypoplasia

18.  Opponensplasty
 An opponensplasty is the preferred to augment the
deficient thenar muscles
 The choice of donor tendon and pulley
reconstruction is debatable
 performed using
 Flexor digitorum superficialis(FDS)or
 Abductor digiti minimi(ADM).
 It is recommended about 1-2 years of age
 The ring finger flexor digitorum superficialis (FDS) has
adequate length for both tendon transfer and UCL
reconstruction.

20.  The abductor digiti minimi(ADM)

21.  First web space deepening
 usually performed with Z-plasty or V-Y flap
 partial release of the insertions of the intrinsic
muscles (ie, first dorsal interosseous, )

22.  Stabilization of MCP joint
 Three options
 Fusion
 Reconstruction of UCL with FDS
 Reconstruction of UCL with free tendon graft

23.  A type IIIA also requires transfers to
overcome the extrinsic musculotendinous
abnormalities
 Extensor indicis proprius(EIP) is good for
Extension of the thumb.
 And reconstruction of the flexor pollicis
longus(FPL).

24. Pollicization
◦ Type IIIB, IV, V hypoplasia
◦ Tips
 Plan skin incision to avoid skin grafts
 Isolate index finger on its
neurovascular bundles
 Detach first dorsal and palmar
interosseous muscles
 Removing most index metacarpal and
epiphyseal plate

25.  Stabilize index MCP joint (40°
ABD, 15°EX, and 120° pronation).
 Reattach and balance
musculotendinous units
 Reconstruct long extensor
tendons
 Rebalance flexor tendons

26.  Type V with
polydactyl

27. Summary
 Thumb hypoplasia frequently associated with
other anomalies.
 Blauth classification with other modifications are
very important for management of thumb
Hypoplasia.
 Good clinical examination with lab investigations
are very important before reconstruction.

28. Thank you