What is thumb hypoplasia?
Congenital underdevelopment of the thumb frequently associated with partial or complete absence of the radius
NB thumb on side of radius
What is the epidemiology of thumb hypoplasia?
Incidence 1/100,000 live births
Location= Bilateral involvement in 60% pts
Right hand > left
What is the pathophysiology of thumb hyoplasia?
Eaxct cause during embrology development is yet to be ellucidated
Name the associated anomalies of thumb hypoplasia?
VACTERL- Vertebral anomalies, Anal atresia, Cardiac defects, Tracheoesophageal fistula and/or Esophageal atresia, Renal & Radial anomalies and Limb defects
Thrombocytopenia- absent radius (TAR)
What is the classification system for thumb hypoplasia?
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
What are the physical findings of thumb hypoplasia?
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
What investigations are useful in thumb hypoplasia?
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
Can you describe an opponensplasty?
An Opposition transfer
Uses Flexor digitorium superficialis or abductor digiti minimi
How do you deepen the first web space, can you draw this?
see picture below
How would you stabilise the MCPJ in thumb hypoplasia?
Reconstruction of UCL with FDS
Reconstruction of UCL with Free tendon graft
Process of creating a thumb from the exisiting index finger
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
reattach and balance musculotendinous units
Reconstruct long extensor tendons
rebalance flexor tendons
What is congenital trigger thumb?
Stenosing tenosynovitis of Flexor pollicis longus at Iat the Interphalangeal joint of the thumb
What is the epidemiology of trigger thumb?
Prevalence is 3 per 1,000 children at 1 year
What is the pathology of congenital trigger thumb?
Thought to be due to CONSTRICTION of Flexor Pollicis Longus (FPL) at A1 pulley
What do you find on examination of a congential trigger thumb?
Fixed flexion deformity cf 'triggering'
Flexor tendon nodule at MC Head- aka Notta's node ( see pic)
What is the Tx of congential trigger thumb?
outcomes- 30% resolve < 1 year old
<10% resolve over 1 year
None resolve if in a 3 yr old
A1 pulley release: if no resolution by 12 months, perform at 12 months.
Complications of congenital trigger thumb?
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
What is congenital clasped thumb?
Deficient Active Thumb extension
Slight limitations of passive extension
Flexion-adduction deformity of the thumb,  pollex varus,  thumb in the hand
What are the classification types of clasp hand?
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
What is the tx of congenital clasp thumb?
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