Congential Thumb Flashcards

1
Q

What is thumb hypoplasia?

A

Congenital underdevelopment of the thumb frequently associated with partial or complete absence of the radius

NB thumb on side of radius

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2
Q

What is the epidemiology of thumb hypoplasia?

A

Incidence 1/100,000 live births

Males= Females

Location= Bilateral involvement in 60% pts

Right hand > left

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3
Q

What is the pathophysiology of thumb hyoplasia?

A

Eaxct cause during embrology development is yet to be ellucidated

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4
Q

Name the associated anomalies of thumb hypoplasia?

A

VACTERL- Vertebral anomalies, Anal atresia, Cardiac defects, Tracheoesophageal fistula and/or Esophageal atresia, Renal & Radial anomalies and Limb defects

Holt- Oram

Thrombocytopenia- absent radius (TAR)

Faconi Anaemia

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5
Q

What is the classification system for thumb hypoplasia?

A

BLAUTH Classification ( see pic)

Tx depends on CMCJ stability

1 = Minor Hypoplasia- all muscleskeletal + neurovascular intact just small hand = NO surgery

2= All bones present. MCPJ + Ulnar collat lig instability

Thenar hypoplasia = Stabilise MCPJ, Release 1st Web space, opponensplasty (opposition tendon transfer)

3A= muscle/bone def. CMCJ intact. Absent active motion MCPJ/ IPJ = Stabilise MCPJ, Release 1st Web space, opponensplasty (opposition tendon transfer)

3B= muscle/bone def. Basal MC aplasia w def CMCJ. Absent active motion at MCPJ/IPJ = Thumb amputation/ pollicization

4= Floating thumb, attach to hand by skin alone = Thumb amputation/ pollicization

5= Complete absence of thumb

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6
Q

What are the physical findings of thumb hypoplasia?

A

Pollex Abductus- FPL attaches to normal insertion and extensor tendon

Hypoplasia of thenar musculature

**Absence of skin creases= **muscle/tendon abnormalities

Range of motion and instability- Ulnar collat lig laxity

Web space tightness

Evaluate for other anomalies- vertebra, anal, cardiac, tracheoesphageal, radius, renal and limbs

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7
Q

What investigations are useful in thumb hypoplasia?

A

xrays- bilateral hands, wrists and forearm

Bloods- peripheral blood smear and FBC= rule out Fanconi anaemia

Chromosomal challenge test= detects Fanconi anaemia before bone marrow failure

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8
Q

Can you describe an opponensplasty?

A

An Opposition transfer

Uses Flexor digitorium superficialis or abductor digiti minimi

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9
Q

How do you deepen the first web space, can you draw this?

A

Z plasty

see picture below

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10
Q

How would you stabilise the MCPJ in thumb hypoplasia?

A

3 options:

Fusion

Reconstruction of UCL with FDS

Reconstruction of UCL with Free tendon graft

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11
Q

Describe pollicization?

A

Process of creating a thumb from the exisiting index finger

Principles are:

Plan skin incision to avoid skin graft

isolate index finger NV bundles

Detach 1st dorsal and palmar interosseous muscles

shorten digit - removing index finger MC and epiphyseal plate

stabilise MCPJ

reattach and balance musculotendinous units

Reconstruct long extensor tendons

rebalance flexor tendons

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12
Q

What is congenital trigger thumb?

A

Stenosing tenosynovitis of Flexor pollicis longus at Iat the Interphalangeal joint of the thumb

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13
Q

What is the epidemiology of trigger thumb?

A

Prevalence is 3 per 1,000 children at 1 year

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14
Q

What is the pathology of congenital trigger thumb?

A

Thought to be due to CONSTRICTION of Flexor Pollicis Longus (FPL) at A1 pulley

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15
Q

What do you find on examination of a congential trigger thumb?

A

Fixed flexion deformity cf‘triggering’

Flexor tendon nodule at MC Head- aka Notta’s node ( see pic)

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16
Q

What is the Tx of congential trigger thumb?

A

Non operative

clinical observation

outcomes- 30% resolve < 1 year old

<10% resolve over 1 year

None resolve if in a 3 yr old

Operative

A1 pulley release: if no resolution by 12 months, perform at 12 months.

17
Q

Complications of congenital trigger thumb?

A

Digital nerve injury whilst doing the A1 pulley release- high proximity to flexor tendon and A1 pulley

Radial digital nerve especially at risk-both nerves hug flexor tendon

18
Q

What is congenital clasped thumb?

A

Deficient Active Thumb extension

Slight limitations of passive extension

Flexion-adduction deformity of the thumb, [2] pollex varus, [3] thumb in the hand

19
Q

What are the classification types of clasp hand?

A

Supple Type- due to weak /absent EPL/EPB

**Rigid **type- due to hypoplastic extensor tendons, MCPJ contractures, Ulna collateral ligament deficiency, thenar muscle hypoplasia and indequate 1st web space skin

20
Q

What is the tx of congenital clasp thumb?

A

Non operative- first line SPLINTING 3-6 months

Operative**- tendon transfer to EPL- **for SUPPLE type with residual deficiency in active extension

**Thumb reconstruction- rigid **type with MCPJ contracture may include web space deeping, opposition transfer, extensor transfer, muscle releases, capsular release, FPL z lengthening