Thumb hypoplasia types and management pollicization of index finger

1. CONGENITAL HAND III –
THUMB HYPOPLASIA
Dr. Satish Kumar.S
Final year MCh resident

2. Introduction
• Represents a wide spectrum of functional and aesthetic differences
• deficiency of any one or all structures that contribute to the “normal” thumb.
• Assessment of thumb:
• (1) size
• (2) position
• (3) relation to other fingers of the hand
• (4) osseous components
• (5) joint integrity and stability
• (6) intrinsic and extrinsic musculotendinous units
• (7) first webspace depth and width
• (8) associated malformations of the hand
• (9) functional consequences for the child.

4. Development
• First 3 months of life
• thumb adducted and flexed within the palm .
• serves as a pacifier.
• 9 months of age
• gains its independence
• mobility from the palm
• 1 year of age
• crucial portion of the hand.

5. • primary ossification centers of the phalanges and
metacarpal of the thumb - second to fourth fetal months
• Secondary ossification centers within the epiphyses of the
thumb - 13 months to 4 years of age
• delayed appearance of both primary and secondary
ossification centers in proportion to degree of hypoplasia.
Development

6. History
• Flatt
• function potential and designated the digits as “adequate” or “inadequate”
• Bayne
• localized positions of deficiencies
• Blauth
• progressive degree of hypoplasia from a slight size discrepancy, with all normal structures present,
to total aplasia of the thumb
• World War II - Bunnell
• digital transpositions
• Littler
• applied them to congenital differences.
• Following thalidomide crisis in Europe - Buck-Gramcko
• large clinical experience and set present day standards for pollicization

7. CLASSIFICATION
• Blauth
• modification proposed by Manske
• subdivides the type III thumb into those with stable CMC joints and unstable CMC joints.
• TYPE I – Mild hypoplasia
• TYPE II – Moderate hypoplasia
• TYPE III – Severe hypoplasia
• A – stable CMC
• B – unstable CMC
• TYPE IV – Floating thumb
• TYPE V – Aplasia of thumb

8. Type I: mild hypoplasia
• Most mild type of hypoplasia
• thumb is slender and slightly shorter
• phalanges and metacarpal - slightly thinner
• trapezium and scaphoid are present
• distal radius and styloid process not affected
• IP, MCP, and CMC joints stable
• may be a slight hypoplasia abductor pollicis brevis , opponens pollicis and lateral head of the flexor
pollicis brevis
• intrinsic muscles present
• joints, ligament and capsules, tendons, nerves, and vascular structures – normal
• minimal narrowing of the first webspace.

11. Type II: moderate hypoplasia
• metacarpal and phalanges - hypoplastic
• trapezium, trapezoid, scaphoid, lunate may be hypoplastic
• first webspace is short with thumb adducted
• ulnar collateral ligament at the MP joint lax
• median innervated thenar muscles underdeveloped
• Best clinical indicator of flexor and/or extensor abnormalities
• absence of IP or MP flexion or extension creases in a slender thumb

14. Pollex abductus
• Extrinsic extensors may have abnormal insertions
• extend over the MP joint in a non-centralized position
• abnormal connections with the extrinsic flexor
• abnormal insertions combined with deviated course
• make tendons act primarily as radial deviators and not flexors or extensors.
• muscles contract
• no IP flexion or extension
• only abduction or radial deviation of thumb

16. Type III: severe hypoplasia
• skeletal shortening and narrowing much more pronounced – metacarpal
• hand and wrist - radially deviated due to hypoplastic/aplastic carpal bones
• trapezium -very small
• Scaphoid- absent
• distal radius - smaller
• styloid process – absent
• Median innervated intrinsic muscles - severely hypoplastic or absent
• Collateral ligament and volar plate - severely hypoplastic or missing

17. Type III: severe hypoplasia
• small thumb with a short webspace is abducted at the MP joint
• extrinsic flexor and extensor are present and weak
• radial origin of the first dorsal interosseous to index finger - severely hypoplastic
• first webspace - severely restricted.

18. Type III: severe hypoplasia
• IIIA
• full-length metacarpal and intact CMC joint
• IIIB
• tapered metacarpal and no CMC joint.
• IIIC (Buck-Gramcko)
• only metacarpal
• no tendons or muscles
• skin bridge is much wider than type IV.

23. Type IV: floating thumb
• Pouce flottant – French
• Pendeldaumen - German
• arise distally from the palm and lie along the radial midaxial border
• a digital artery, two vena comitantes
• one or two nerves within the skin bridge
• no metacarpal
• two small phalanges
• diminutive nail represents distal phalanx
• Intrinsic muscles do not insert onto these bones
• Trapezium and scaphoid absent
• Radial styloid may be absent, but distal end of radius is normal

25. Type V: aplasia
• thumb is completely absent
• radius is normal
• index digit is normal
• strong abduction at the MP joint due to the presence of a strong first dorsal interosseous
• Autopollicization
• pulp of the index finger widens
• digit pronates and sits in a more abducted position
• widening of the intermetacarpal space
• the index ray is stiffer, shorter
• often joined by simple syndactyly to the long digit
• fifth finger always the best on the hand

27. Type VI: central deficiencies – cleft hand and
symbrachydactyly thumb
• CLEFT HAND
• hypoplasia or aplasia of the central ray forming a “V” or funnel-shaped cleft
• moderate to severe deficiencies of first webspace
• thumb usually slightly small with all skeletal components present.
• Carpals, radius, ulna normal
• Median innervated thenar intrinsics present
• Ulnar innervated intrinsic - severely hypoplastic or absent.
• first dorsal interosseous, extrinsic flexor and extensor units - unaffected

29. Symbrachydactyly thumb
• always unilateral
• varying degrees of hypoplasia of the central three rays
• Nubbins with minute nail complexes
• All degrees of variation exist
• Thumb - invariably smaller
• severe hypoplasia or aplasia of the phalangeal components
• median innervated thenar intrinsic muscles are intact
• fifth ray usually the best in the hand
• Radius and ulna are present
• may be small in comparison to opposite limb.

31. Type VII: constriction ring syndrome
• amniotic band sequence
• Streeter’s dysplasia
• fenestrated syndactyly
• acrosyndactyly
• deficiency in the length of the thumb
• transverse failure of formation at any level
• anatomy proximal to the level of band - normal
• hypoplasia or lymphedema of distal segment
• hypoplastic nail remnants
• slender, truncated phalanges

33. Type VIII: five-fingered hand
• Thumb is smaller in width longer in length and has the characteristics of a finger
• lies in same plane as the ulnar four digits and non-opposable
• same length as adjacent index finger
• may be joined to index finger - incomplete simple syndactyly.
• Severe deficiency first web
• Metacarpal with a distal growth center and three phalanges with proximal growth centers.
• scaphoid absent or hypoplastic
• Thenar musculature absent
• Instead digital intrinsics are present – lumbrical, palmar and dorsal interosseous
• extrinsic flexors and extensors mimic those of the normal fingers

35. Type IX: radial polydactyly
• abnormalities in nail plate, osteoarticular column, intrinsic and extrinsic
musculotendinous units
• pollex abductus
• first web unaffected in polydactylies of distal phalanx
• level of arborization lies more proximally - first webspace becomes
increasingly deficient and tight.

36. Type X: syndromic short skeletal thumb ray
• Deficiencies of the osteoarticular column of the thumb
• short, hypoplastic thumb
• anomalies of a single bone, brachymetacarpia, or brachyphalangia,
• Remaining components of the thumb - unaffected
• whole spectrum of patients with metabolic bone diseases, skeletal dysplasias, benign skeletal
tumors, and many syndromes may include thumb hypoplasia

37. MANAGEMENT
• Ideal prerequisites for reconstruction of a functional thumb –
1. mobile, stable CMC joint with an intact metacarpal
2. scar-free first webspace of adequate width and depth lined with full-thickness skin
3. Mobility in at least two of its three joints (CMC, MCP, IP)
4. MCP joint stability, particularly of the ulnar collateral ligament
5. Adequate motors for strong MP or IP flexion and extension
6. Capacity to be placed in a palmar abducted position for pinch and grasp maneuvers

38. TIMING
• EARLY vs LATE
Pros -
• Anatomically - release of tethered musculotendinous units and joint contractures will allow
unrestricted growth
• physiological - adaptation of the reconstructed thumb will occur secondary to growth and functional
use.
• Cognitive level - prior to thumb corticalization - 18 months of age better devolopment
• Psychologically - correction will alleviate anxiety in the parents and child.
Cons -
• growth-related complications
• Functional need assessment
• patient cooperation

39. Type I: mild hypoplasia
• not usually functionally impaired
• Very little or no difficulty with key pinch, pulp-to-pulp pinch, opposition and grasping activities.
• surgical correction - not often needed.
• Might require release of mildly contracted web
• four-flap Z-plasty provides the best contour and appearance

40. Type II: moderate hypoplasia
• Five specific problems must be addressed individually
1. narrowed first webspace
2. instability of MCP joint
3. poor palmar abduction (opposition) for pinching and grasping
4. lack of IP joint flexion
5. pollex abductus
• release of first webspace
• stabilization of MP joint
• with or without tendon transfer for opposition

41. Type IIIA: severe hypoplasia
• Five specific problems
1. narrowed first webspace
2. instability of MCP joint
3. poor palmar abduction (opposition) for pinching and grasping
4. lack of IP joint flexion
5. pollex abductus

42. Index finger pollicization - treatment of choice
• Type IIIB, type IIIC: severe hypoplasia
• Type IV: floating thumb
• Type V: aplasia

43. Deficient first webspace
1. local transposition flaps
2. Local rotational or sliding flaps with or without skin grafts
3. regional vascular island flaps
4. free fasciocutaneous tissue transfer
5. distant pedicled flaps
6. use of skin expansion

44. Deficient first webspace
• Lengthening the contractual limb of the Z-plasty five-flap (“jumping man”) technique
involves small flaps with vulnerable tips.
• Simple Z-plasty - does not give the proper contour
• creates central depression at the base of the webspace
• 4 flap z plasty - ideal
• local flaps with skin grafts on dorsum of hand or on index - popular but not preferred
• Distally based radial artery or PIA flap
• Free groin flaps

47. MCP joint instability
Stabilization of lax joint in type II and IIIA thumbs :
1. tightening of the existing ligament and capsule
2. free tendon graft reconstruction
3. ligament reconstruction using the end of a tendon used to improve palmar abduction (opposition)
4. Arthrodesis or chondrodesis
• In growing child, all must be performed without injury to the growth plate
• FDS is used simultaneously for palmar abduction (opposition)
• one slip is passed through a bone tunnel in the metacarpal neck to be used on the ulnar side
• other slip for the radial side of the joint

48. MCP joint instability
• IIIA thumbs
• with flail joints and poor extrinsic motors
• stability more critical than motion
• chondrodesis in young child or
• arthrodesis in adolescent
• MC head shaved without injury to growth plate and fused to epiphysis of PPx
• Tendon graft stabilization
• palmaris tendon
• ring finger FDS

49. Poor/absent palmar abduction (opposition)
• key pinching maneuvers
• cannot abduct thumb for pulp-to-pulp pinch or grasp
• two-handed grasp for holding larger objects.
• transfer of either the abductor digiti minimi or FDS of ring finger

50. Technique of ADM transfer
• Incision from pisiform proximally to mid-axial line of PPx
• muscle harvested and passed through subcutaneous tunnel made between the skin and palmar
fascia and attached to -
1. 1st metacarpal
2. radial collateral ligament at the MP joint or
3. the abductor aponeurosis
• Advantage of myocutaneous ADM
• Improving the soft-tissue deficit in the palm

53. Technique of FDS transfer
• Longitudinal incision at the base of the ring finger
• A1 pulley is released
• finger flexed
• Both slips of FDS pulled into the wound and cut as far distally as possible
• Tendon delivered through incision over FCU dorsally
• Passed through subcutaneous tunnel to radial side of the thumb
• Pivot point for the transfer - through Guyon’s canal or around FCU.
• two slips of the FDS - reconstruction of the radial and ulnar collateral ligaments

55. Lack of IP joint motion
• Ring FDS for IP flexion
• EIP for IP extension

56. Pollex abductus
• flexor and extensor tendons are exposed through radial incision
• interconnecting bands along the radial side of the MCP joint and PPx - divided and excised
• Pulley system strengthened by
1. tendon graft
2. piece of extensor retinaculum

57. Pollicization
Principles
1. transposition of the index digit as a vascular island
2. rotation and recession shortening of the ray
3. rebalancing of muscles and tendons
4. create a normal first web

58. Procedure
• A racquet-shaped incision – around base of index ray along MCP flexion crease and extends down
the radial border of the hand
• Site of new thenar flexion crease is marked and distal portion of incision is connected to the incision
around index ray.
• If a type IIIB, C or IV thumb is present, the skeleton is filleted from soft-tissue envelope and intrinsic
muscles transferred to new thumb

59. • Index extrinsic flexors not altered and lumbrical left
intact
• A1 pulley is decompressed
• On the dorsal side, EDC and EIP to index are
isolated and divided at the level of MCP joint.
• lateral bands are separated from common extensor
over PPx
• index finger is now “recessed and rotated” and
secured anterior to the base of the index metacarpal
with one or more interosseous sutures
• In this position, the MCP joint must be
hyperextended between 60 and 80°

60. • EDC is sutured to ulnar base of index PPx - AbdPL
• 1st volar interosseous becomes new AddP -
attached to ulnar collateral ligament at MCP joint
• 1st DI - new Abductor PB- inserted into the radial
collateral ligament or the radial base of new PPx

61. • First, new thumb thenar flexion crease is sutured with the thumb in palmar
abducted position.
• In this position, dorsoradial flap of the index finger is advanced toward MCP joint
of middle finger to create a normal appearing webspace
• flaps on the radial side of the thumb are trimmed and closed

65. Postoperative care
• Immobilization in a well-padded long arm cast - 3–4 weeks
• next 6–8 weeks compressive dressing at night to reduce swelling
• Thumb spica thermoplast splint at night
• the child works with the parents using special play activities
• long and ring digits are buddy taped to encourage key pinch and grasp using new thumb.
• By 6 months postop
• all children will have actively integrated thumb into activities of daily living.

66. Outcomes pollicization
• New thumb will never be normal
• preop condition determines postop result
• newly created CMC does not have same degree of freedom as the normal jt
• normal cone of thenar intrinsic muscles are absent
• strength and stability in pinch and grasp maneuvers does not approach normal
• total active range of motion averaged 50% of normal
• standard grip strength 21%
• lateral pinch 22%
• use in normal activities 84%

67. Complications
• Venous compromise
• Adduction contractures of the new thumb
• Aseptic necrosis of the new trapezium
• growth arrest of the proximal phalanx (new metacarpal)
• Ossification of the periosteal tissue

68. Treatment of other types of thumb hypoplasia
(types VI–X)
Cleft hand
• Principles to be followed:
1. Release the first web syndactyly and contracture
2. Maintain maximal thumb mobility
3. Preserve the adductor pollicis, if present
4. Rotate full-thickness skin flaps into first webspace
5. Release any syndactyly involving the two ulnar digits

69. Cleft hand
• thumbs are triphalangeal –
1. stable, well-aligned, mobile but long thumb is left uncorrected
2. longer, flexed, or deviated triphalangeal thumbs should be treated.
• Shortening the thumb -
• excision of the extra phalanx or osteotomies
• Causes stiffening
• Some cases, no phalangeal segments are present-
• vascularized toe to thumb transfer using the distal portion of great toe (if present) is preferred
• Distraction lengthening
• Motion is poor, but sensation is good

71. Symbrachydactyly thumb
• most functional
• Almost all can oppose thumb to the small finger
• hypoplastic thumb with good MP motion, stable joints, and present thenar intrinsics – no
Sx
• Excision of non-functional nubbins will improve the shape and provide a deeper
webspace for grip
• lack pulp-to-pulp pinch due to poor pronation of thumb
• Rotational osteotomies at metacarpal level will resolve this problem
• severely hypoplastic thumb, with absent or diminutive PPx and flail MP joint
• non-vascularized toe phalangeal transfer into the proximal phalangeal level
• Transfers are more likely to grow if performed before 1 year of age

73. Type VII: constriction ring syndrome
• Principles of management –
1. Immediate treatment of any vascular compromise or progressive lymphedema
2. Early liberation of thumb ray when involved with syndactyly
3. Release of adduction contractures within first webspace and
resurfacing with full thickness tissue prior to any augmentation of thumb length

74. Type VII: constriction ring syndrome
• Constriction ring at TPx level at or beyond the interphalangeal joint-
• no operative intervention
• Only correction of proximal constriction ring.
• nail and palmar pulp atrophic but thumbs are functional.
• Instability at IP joint - collateral ligament reconstruction with tendon graft
• Thumb length augmented by -
1. Distraction lengthening at the metacarpal level
2. Non-vascularized toe phalangeal transfer
3. Composite vascularized toe-to-thumb transfer

76. • Distraction lengthening
• performed at the metacarpal level
• two-staged procedure
1. application of distraction apparatus and osteotomy
2. bone grafting of the intercalated gap and internal fixation

78. Five-fingered hand
• pollicize radial digit
• technique similar to that for thumb aplasia (type V)
• secondary opponensplasty
• with ADM or ring FDS transfer- occasionally necessary.
• most important procedure - creation of broad first webspace with unscarred flap tissue

80. Syndromic short skeletal thumb ray
• Do not require any treatment
• length deficiency is mild
• distraction lengthening with a secondary bone graft at metacarpal level
• generalized syndromes require a multidisciplinary approach
• hand procedures coordinated with other required treatments

82. The inadequate index finger
• less than normal (i.e., stiff) index finger is available for potential pollicization
1. syndactylized index ray in a child with Holt–Oram syndrome
2. index joined to the long finger with a complete simple syndactyly
3. stiff index finger associated with a complete or partial absence of the radius
4. stiff index ray with a fixed proximal interphalangeal joint flexion contracture with or without a
complete or partial absence of the radius
5. mirror hand (ulnar dimelia)
6. five-fingered hand.

83. • Options for reconstruction
1. no surgical treatment (syndromic associations, which include major central neurologic deficits)
2. rotation–recession osteotomy of the index ray
3. formal pollicization of index ray
4. pollicization of the fifth finger

84. THANK YOU !