Download Undergrowth

Hypoplasia/undergrowth
Thumb hypoplasia
 Spectrum of deformities ranging from minimally short thumb to an absent thumb
 hypoplasia of hand most commonly affects thumb
 May be sporadic or inherited (Holt Oram) or in association with absent radius
Classification - by Blauth (modified by Manske)
Grade
Treatment
Grade one
Thumb slightly smaller but all components present,
Thenar muscles and 1st web normal
Surgery not required and function not impaired
Grade Two
Small thumb with hypoplasia of thenar muscles,
adduction of first web and laxity of UCL of MCPJ
1st Web release, opponensplasty, re-insertion of tendons
and reconstruction of MCP Jt ligaments
Grade Three
Absent thenar muscles, abnormal extrinsic tendons and
skeletal hypoplasia, severe 1st web contraction, MCPJ
unstable
3a – CMCJ stable
thumb reconstruction as in Grade 2
Reconstruction of EPL and or FPL
3b - CMCJ is significantly aplastic and unstable
pollicization of IF
free MTPJ or IPJ transfer for CMC reconstruction
Free toe to thumb
Grade Four
Floating Thumb (pouce flotant)
Attached to hand
by skin only contains two rudimentary phalanges and
single neuro vasc bundle and has no function
Pollicization early
Free Toe to thumb
Grade five
Total aplasia of thumb, absence of entire osteoarticular
column and all the soft tissue
Pollicization
Free Toe to thumb
Techniques
Release of web
 Widening and deepening of the contracted web space in grade 2 hypoplasia
requires the release of skin and any underlying tight, deep fascia.
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Z plasty - Zplasty, or four flap z-pasty may improve mild contractures only
Local flaps – dorsal transposition flap from the dorsum of the index finger may be
required. The donor defect is covered by FTSG
Regional flaps – Reverse radial forearm
Free flaps – groin flap
Opponensplasty:
 Restoration of opposition requires transfer of an active muscle unit.
 The superficial tendon of the ring finger or the abductor digiti minimi can be used.
 FDS to RF has better excursion
 FDS exposed though incision through proximal digital crease and retrieved distal
to the flexor retinaculum and rerouted to be looped through the proximal phalanx
and the distal metacarpal, thus reconstructing the lax UCL
 Huber transfer - Abductor digiti minimi is passed through a tunnel and sutured to
the hypoplastic abd pollicus brevis.
Stabilization of MCP Joint
 When the UCL is lax, may be reinforced with a tendon graft. Usually sutured to
thick periosteum.
 If holes required in bone care taken not to damage the growing epiphysis
 Stabilization difficult in setting of hypoplastic muscles thus arthrodesis may be
required.
Tendon adjustment
 When the normal skin crease of the thumb is absent or poorly developed, or when
there is deviation of the distal interphalangeal joint, anomalies of the extrinsic
tendons may be present.
 In some cases where the thenar muscles are absent, the FPL may run a very
superficial course, connecting with the extensor pollicus longus and brevis
tendons and inserting in to the lateral digital sheet to exert an abduction force on
the distal phalanx. Useful flex and ext may not be possible and this complex may
exert a powerful abductor force in poorly stabilized joints of the thumb.
 The anomalous flexor extensor connection (pollex abductus) needs division. The
power of the existing may be improved by reinsertion of the tendon.
Pollicization – Buck gramcko
Timing - 1st year of life
Theoretical concepts
 In creating a new thumb with stability and optimum length a reduction in the
length of the bones is important. Thus the second metacarpal except its head is
removed. The head acts a trapezium and thus attaining the same number of bones
as a thumb
 The metacarpal should not be allowed to grow much thus the epiphysis is
removed
 Rotation of the IF on its longitudinal axis is also performed to provide proper axial
alignment
 The IF needs to be rotated 160 so it is opposite to the pulp of the RF during
suturing the rotation ends up at about 120 degrees
 MCPJ should be in 40 of palmar abduction, 15of extension and 120of
pronation
Operative technique
Four important techniques relating to the following
1. the neurovasc pedicle
2. skeletal readjustment with the preservation of the MCP joint
3. muscular stabilization
4. the skin incision
The N/V bundle
 Freeing up the NV bundle between the IF and RF obtained by ligating the proper
digital artery to the radial side of the long finger.
 The radial artery to the IF is often small or absent
 The common digital nerve is then carefully separated into its component parts of
the two adjacent fingers
 Occasionally there is a Hartmanns boutonniere, where the common digital
artery passes through the digital nerve – do internal neurolysis to mobilize but try
not to cut the nerve
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On the dorsal side at least one of the great veins must be preserved
The skeletal readjustment
1) The Transverse metacarpal ligament is divided and the metacarpal shaft is
exposed to allow excision.
2) The ideal length of the new thumb should meet the MF PIPJ crease in adduction
3) Intrinsics are stripped off the shaft up to proximal 1/3 to preserve nerve supply,
their distal tendons divided and metacarpal head is excised
4) Presence of 1st dorsal interossei and lumbrical is key for a good result
5) The physis is curreted to destroy growth potential and the head is fixed by sutures
to the joint capsule and the carpal bones. 2 Kwires are used.
6) The head is rotated 70 -80 degrees such that its palmar side becomes more
proximal (see figure) ie the prox phalanx is brought into a position of
hypertextension with respect to the proximal phalanx and thus prevents
hyperextension deformity.
7) The IF is also rotated by 160 degrees
Skin incisions
 At the base of the index finger an incision is fashioned to form a long 70 V on
the dorsal aspect extending to a point overlying the neck of the metacarpal.
 1/3rd from the apex to the ulnar midlateral line, a longitudinal incision is made
extending to the index PIPJ (line B)
 It is carried through skin only to preserve vessels and nerves.
 Curvilinear palmar incision from midpoint of the digital crease incision to the
distal wrist crease
 Both neurovascular bundles are kept intact if present, however one is usually
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dominant.
On the ulnar side of the digit the nerve is dissected from the common digital nerve
towards the base of the palm.
The arterial branch to the radial side of the middle finger is ligated to mobilize the
ulnar digital vessel of the index finger.
On the dorsal aspect two veins should be preserved
Tendon transfers/ muscle stabilization
 The intrinsic and extrinsics are essential for the stability of the operation
 the EDC is cut at the MCP joint level and prox end sutured to the base of the
former prox phalanx now acting as a MC to become the new abductor pollicus
longus
 The EI tendon is divided and shortened (to length of metacarpus shortening) and
then resutured to act as a EPL
 The interossei are divided distally and their origin is carefully stripped of the
metacarpal shaft in subperiosteal dissection. They are then sutured to the two
lateral bands
 Tendon of first dorsal interosseous is moved distally and sutured to the radial
lateral band to function as short abductor.
 If this absent (50%), suture EDC more distally and volarly to the proximal
phalanx shaft
 Later, FDS or ADM opponenplasty may be done
st
 1 palmar interosseous tendon is sutured to ulna side lateral band to act as
adductor
 The two flexor tendons do not need to be shortened in young because they
readjust over 6mths in older children shortening speeds recovery
 Summary
1. EDC sutured to P1 to become APL
2. EI sutured to EPL (if present)
3. 1st DI and lumbrical to radial lateral band
4. 1st VI to ulnar lateral band
Postoperative management
 Well padded dressing applied with plaster in older children
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Dressing and k wire removed at 4 wks
Taping the remaning digits or wearing a mitten will encourage prehensile use of
the new thumb
takes upto 6 mths to achieve final functional result
Improved with judicious hand therapy
Complications
 Necrosis due to tight dressings, hematoma or vessel thrombosis (rare
complication)
 Marginal flap necrosis
 Joint imbalance - if metacarpal head is not rotated to prevent hyper ext of the
thumb
 Tendon imbalance
 Nerve supply to dorsal interosseous damaged - corrected with FDS
opponensplasty
Grade IIIa reconstruction with toe joint transfer
 extrinsic tendon abnormalities includes absent extensor pollicis longus tendon,
absent or aberrant flexor pollicis longus tendon, tendon interconnection between
the flexor pollicis longus and extensor aponeurosis, duplication of
musculotendinous units, anomalous muscles between the thumb and index rays,
and abnormal insertions or dense adhesions along tendons as proximal as the
forearm level.
 Repair requires
1. extended approach from the digit to the forearm, through which division of
abnormal connections, reorientation of tendons, and lysis of adhesions was
performed.
2. If EPL/FPL absent, reconstruct
3. UCL reconstruction of MCJ
4. 1st web space widening
5. opponensplasty if required
Grade IIIb with joint transfer
 functionally and cosmetically inferior to the ones observed after pollicization.
 Use vascularized second toe proximal interphalangeal joint transfer for
carpometacarpal joint replacement
 Otherwise similar to IIIa repair
 May need to perform in 2 stages
Free toe transfer
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2nd toe and metatarsal head often used
Avoid use of 1st toe due to sacrifice of the metatarsal head
Similar concepts to pollicisation but with the micro
Opponensplasty required
Hypoplastic digits
 Short under developed digits associated with many cong hand deformities
 Usually digits are skin tubes with deficient underlying structures
 Treatments involve free phalangeal transfer from toes or distraction lengthening