Embryology of the Upper limb and congenital hand anomalies Flashcards
1
Q
Describe upper extremity embryogenesis
A
- Wk 4-8 - at end of embryogensis, structures are present (including cartilage, not bone) and will then differentiate/mature
- at birth - carpal bones and epiphyseal plates not yet ossified/not visible on xray
3 axes of development
- derived from MESODERM (lateral plate & somatic)
- PROXIMODISTAL = AER and PZ
- Apical Ectodermal Ridge controls the apoptosis interdigital and guides differentiation of cells in Progress Zone defines digits
- ANTEROPOSTERIOR = ZPA
- Zone of Polarizing Activity defines A-P axis by amount of SHH signalling defines thumb on radial side
- DORSOVENTRAL = WNT
- Wnt singnalling in dorsal ectoderm defines nail pulp from plate
OSSIFICATION
- clavicle first to ossify
- Radius, ulna, DP, MC, PP, MP
- Carpal bones post natal - C, H, Tq, L, STT, Pisiform
2
Q
How do you classify and list congenital upper extremity deformities
A
IFSSH
- FAILURE OF FORMATION
- transverse arrest
- longitudinal arrest
- Ulnar longitudinal deficiency
- Radial longitudinal deficiency
- Central ray deficiency (cleft hand
- longitudinal Intercalary deficiency (phocomelia)
- FAILURE OF DIFFERENTIATION
- Syndactyly
- Apert
- Acrosyndactyly
- symphalangism
- clinodactyly
- camptodactyly
- arthrogriposis
- flexed thumb
- trigger
- clasped
- Syndactyly
- DUPLICATION
- Polydactyly
- preaxial (thumb)
- postaxial (little)
- axial (central)
- Ulnar dimelia (mirror hand)
- Triphalangism
- Polydactyly
- UNDERGROWTH
- symbrachydactyly
- hypoplastic/adactyly
- OVERGROWTH
- macrodactyly
- limb
- CONGENITAL BAND SYNDROME
- GENERALIZED SKELETAL ABNORMALITIES
3
Q
What is the incidence of congenital hand anomalies
A
1/600
and 10% of these have functional sequelae
4
Q
What is the etiology of congenital hand anomalies
A
- Unknown (60%)
- Genetics (30%)
- unknown mutations
- Environment (10%)
- Warfarin => limb hypoplasia
- Dilantin => nail dysplasia, DP hypoplasia
- Alcohol => nail dysplasia, DP hypoplasia
- Thalidomide => phocomelia
- Varicella =>longitudinal deficiency
5
Q
At what age is power grip, tip pinch and hand preference established?
A
- power grip: 7mths
- tip pinch: 9mths
- hand preference 3-4yo
6
Q
What are the goals of surgical planning for correction of congenital hand anomaly
A
- precise pinch
- palmar pinch most used
- lateral pinch also important
- tip pinch precise but used less often
- power grasp
7
Q
Failure of formation: Transverse arrest
What is the etiology, clinical presentation, management
A
- Etiology
- sporadic mutation
- RFs: smoking, cocaine, misoprostol, CVS
- Clinical presentation
- usually, LEFT, UNILATERAL
- level of amputation proximal forearm most common, then midcarpal/metacarpal
- named according to last present structure
- contralateral and proximal structures hypoplastic
- may have finger nubbis/nails
- Management
- prosthesis is mainstay
- may remove nubbins or not (usefu lfor sensory feedback)
- revision of stump for prosthesis fitting
8
Q
Failure of formation: longitudinal deficiency, Radial
What is the etiology, clinical presentation, classification
A
- Etiology:
- injury to AER
- Clinical presentation
- RIGHT, MALE
- 50% bilateral
- 50% associated with congenital syndrome
- On exam -
- wrist: unstable, radially deviated, pronation
- ulna - bowed, shortened
- radial structures absent (including muscle, nerve, vessel and upper arm/BP too
- Classification: Baynes & Klug
- Type 1 - <2mm hypoplastic radius
- short epiphysis
- no wrist angulation
- Type 2: >2mm hypoplastic radius
- short epiphysis and proximal hypoplasia
- wrist radially deviated, supported
- ulna bowed
- Type 3: partial absence of radius
- wrist radially deviated, unsupported
- ulna thick, bowed, shortened+ anlage (fusion of tendon/fibrous tissue 2’ to absnt muscle)
-
Type 4: Absent radius
- most commone type
- wrist: unstable, radial, pronated
- ulna short bowed, anlage
- elbow may be unstable
- Type 1 - <2mm hypoplastic radius
9
Q
What syndromes are associated with radial longitudinal deficency and what work-up is necessary if RLD is identified?
A
- Holt-Oram
- ASD/VSD
- VACTERL
- Verterbral, Anam, Choanal/Cardiac, TE fistula, Renal, Limb
- TAR
- thrombocytopenia + absent radius
- Fanconi
- pancytopenia, ASD, poly/clino/syndactyly
- Nager
- craniosynostosis
WORK-UP
- blood panel (low plat, pancytopenia)
- cardiac echo (HO, VACTERL, Fanconi)
- renal U/S (VACTERL)
- xrays
10
Q
How what are treatment options for RLD?
A
Non-operative
- start at birth
- splinting, serial casting, PT/hand therapy
- improve position of wrist, maintain full PROM
Operative
Indicated: no wrist stability, extensor excursion
Contraindicated: elbow stiff (want wrist radial to feed)
- Wrist/Hand
- centralization: realign 3rd MC with distal ulna and fixate (steinmann/kwire)
- radialization: realign 2nd MC with distal ulna
- ulnocarpal arthrodesis
- closing wedge ulna osteotomy
- Soft tissue relese/rebalance
- tendon trasner FCU to ECU
- release anlage to achieve ROM (watch median nerve
11
Q
Failure of formation: longitudinal deficiency, Ulnar
What is the etiology, clinical presentation, classification
A
- Etiology
- ZPA abnormal
- Clinical presentation
- elbow unstable, fixed in flexion. fused w radius
- wrist stable
- Many associated HAND abnormalities: thumb hypoplasia, syndactyly ulnar digit, absense radial digit
- wrist deviated ulnar
- 25% bilateral
- 50% associated with MSK defect or 3 syndromes (CdL, PFFD, Schinzel)
- Classification (Baynes)
- Type 1 - ulna hypoplastic
- distal + proximal epiphysis present
-
Type 2 - partial ulna absence
- most common
- presence distal 1/3 only
- Type 3 - total ulna absence
- Type 4 - radiohumeral synostosis (fusion)
- Type 1 - ulna hypoplastic
12
Q
What 3 syndromes are most commonly associated with ULD and what MSK abnormalities are associated w ULD
A
- Cornelia de Lange
- excess facial hair, short, DD, seizure
- PFFD
- proximal femoral focal deficiency
- Schinzel
- renal abnormalitiy, DD
- MSK abnormalities
- scoliosis, spia bifida
- fibula/femur deficiency
- contralat phocomelia
13
Q
What are treatment options for ULD
A
Non-operative
- splinting, serial casting to maintian PROM
Operative
- Correct ass. HAND abnormalities
- thumb recon: pollicization, web deepen, MC rotational osteotomy
- syndactyly release
- wrist/forearm/elbow
- release anlage
- rerotational radius osteotomy/humerus
14
Q
What are difference between ULD/RLD
A
- Incidence: RLD 10x more common
- Associated syndrome/abnormalities
- RLD - cardiac/renal/hematopoetic
- ULD - MSK, DD
- Hand abnormalities
- RLD - thumb
- ULD - syndactyly ulnar digit, absent radial 2-3digits
- Elbow/wrist
- RLD - elbow stable, wrist unstable
- ULD - wrist stable, elbow unstable
*
15
Q
Failure of formation: longitudinal deficiency, Central
How do you distinguish between the 2 types of central deficiency
- cleft hand
- symbrachydactyly
A
- Cleft hand = D5 intact
- V-shaped cleft
- variable deficiency of D3
- hypoplasia of radial digits
- syndactyly 1st web
- AR/sporadic genetics
- MALE
- BILATERAL
- may have 1-4 limbs affected
- no finger nubbins
- carpal bones normal
- Associated with: EED (ectrodermal-ectrodactyly Dysplasia w clefting), eye, nail, teeth abnormalities
- Symbrachydactyly (thumbs up!)
- U-shaped cleft
- involves D2,3,4, leaving only D1/D5
- hypoplasia/absence of ulnar digits
- finger nubbins present
- sporadic - no inheritance
- UNILATERAL
- only hands affected, normal legs/feet
- carpal bones hypoplastic
- Associated with POLANDS syndrome
- Common to both
- transverse lying MC bones
- triphalangeal thumb, Longitudinal Bracketed epiphyses (clinodactyly)
- PIP flexion contracture (camptodactyly
