Congenital / Pediatric Trigger Digits (Trigger Thumb & Trigger Finger)

Terminology and Classification

Trigger thumb in a 2-year-old child - note the fixed flexion posture of the thumb interphalangeal joint. (Campbell's Operative Orthopaedics, 15th Ed., Fig. 85.79A)

Epidemiology

• Incidence: ~3 per 1,000 children diagnosed by age 1 year
• Males and females affected equally
• 25% of cases are bilateral
• More prevalent in Asian and Hispanic populations
• Possible genetic predisposition: autosomal dominant inheritance with variable penetrance has been reported; higher concordance in monozygotic twins
• Associated conditions (especially with trigger finger): trisomy 13, juvenile rheumatoid arthritis, mucopolysaccharidosis

Pathophysiology

Trigger Thumb

• Abnormal collagen degeneration and synovial proliferation cause the FPL tendon to thicken
• An intratendinous nodule called Notta's nodule forms proximal to the A1 pulley - it is palpable on clinical examination
• Biopsy consistently shows fibroblasts and mature collagen without inflammatory or degenerative changes, arguing against infectious or inflammatory etiology
• The tendon thickening prevents smooth passage through the A1 pulley, causing the characteristic locking in flexion

Trigger Finger (Less Common in Children)

• Abnormalities may extend from the A1 pulley up to the A3 pulley (broader involvement than in adults)
• Abnormal nodularities in both the flexor digitorum superficialis (FDS) and profundus (FDP) tendons
• Abnormal decussation between FDS and FDP tendons
• Campbell's Operative Orthopaedics, 15th Ed., 2026, block42

Clinical Presentation

• Child presents in the first few years of life with a relatively fixed flexion posture of the interphalangeal (IP) joint of the thumb
• Even with passive force, full IP extension may be impossible
• The "snapping/clicking" sensation typical in adults is usually not the presenting complaint in children
• Notta's nodule may be palpable at the base of the thumb (volar side, proximal to the A1 pulley)
• Neurovascular status is typically preserved

• Usually not noted until the patient is several years old
• Snapping sensation with active finger motion at the proximal interphalangeal (PIP) joint
• May present as a fixed flexion deformity

Natural History

• One third to two thirds of trigger thumbs resolve without surgery
• Hutchinson et al.: 32% spontaneous resolution at 5 years; Baek et al.: 76% over 5 years
• Spontaneous resolution is more likely if the initial contracture is < 30 degrees
• Fixed contractures are unlikely if the condition resolves or is surgically corrected before age 3
• For trigger finger: 63% spontaneously resolve at an average age of 60.1 months

Treatment

Conservative (Non-operative)

• Observation alone has limited effectiveness
• Extension splinting (at least 3 hours/day) significantly improves outcomes over observation alone: 67% resolution with splinting vs. 30% with observation alone (Shiozawa et al.)
• More effective in early, flexible deformities where IP joint is not yet fixed
• Corticosteroid injections are used in adults but are generally not recommended in children

Surgical

1. Tourniquet control; transverse incision at the volar crease of the MCP joint of the thumb
2. Carefully protect the two digital nerves
3. Identify the prominent flexor sheath just beneath subcutaneous fat
4. Identify the proximal edge of the A1 pulley and completely incise it longitudinally under direct vision
5. Shaving the nodule or excising a segment of the A1 pulley is generally unnecessary
6. Close wound; soft dressing; no particular immobilization required

• Traditionally recommended around age 3 if spontaneous resolution has not occurred
• Han et al.: excellent results even at an average age of 7.5 years, with return of near-normal motion by 2.7 weeks postoperatively

• Bruner incision centered over the MCP joint and A1 pulley
• Must visualize the flexor tendon sheath and tendons from the A1 to A3 pulley
• Carefully evaluate for tendon nodularities and abnormal FDS/FDP decussation
• Low threshold to resect a slip of FDS to reduce tendon volume within the sheath
• Using A1 pulley release + FDS slip resection: 91% success rate (Bae, 23 patients)
• Release A3 pulley if triggering persists
• Campbell's Operative Orthopaedics, 15th Ed., 2026

Summary Table

Streeter's Dysplasia (Constriction Ring Syndrome / Amniotic Band Syndrome)

What Is It?

Etiology and Pathophysiology

1. Exogenous (Amniotic Band) Theory - Fibrous bands form from rupture or delamination of the amnion in utero, creating free-floating strands that wrap around and constrict developing fetal parts. This is the most widely accepted theory.
2. Endogenous (Vascular Disruption) Theory - Failure of development of subcutaneous tissue (similar to how normal skin creases form), or hemorrhages in the distal rays causing adhesions. Some argue these defects arise from vascular disruption rather than external bands.

• Not inherited - there is no evidence of hereditary predisposition; it is a sporadic occurrence
• Deformations occur later than 5-7 weeks of gestation (when most hand anomalies occur); the youngest fetus described had this anomaly at 10 weeks gestation
• The condition is classified under the deformation category in the current OMT (Oberg-Manske-Tonkin) classification, not under malformations
• Campbell's Operative Orthopaedics, 15th Ed., 2026; The Developing Human - Clinically Oriented Embryology

Types / Classification (Patterson Classification, 1961)

Clinical Features

• Grooves vary in depth and circumference - sometimes appear as misplaced normal skin creases
• Shallow rings: skin often normal, but subcutaneous tissue is deficient beneath
• Deeper rings: superficial blood vessels crossing the ring are absent (deep vessels intact)
• With deep, unrelenting rings: progressive necrosis, scarring, and vascular impairment can occur

• Lymphedema distal to the crease is frequent
• Cyanosis and worsening constriction can occur before surgical intervention
• Digits distal to rings may be shortened or completely amputated
• Terminal simple syndactyly with small fenestrations is common

Figure 85.78A - Z-plasty incision planning for constriction ring syndrome release (Campbell's Operative Orthopaedics, 15th Ed.)

Associated Anomalies

• Syndactyly, hypoplasia, brachydactyly
• Symphalangism, symbrachydactyly, camptodactyly

• Clubfoot (talipes equinovarus)
• Cleft lip and/or cleft palate
• Cranial defects

Prenatal Diagnosis

• Prenatal ultrasound can detect ABS - visualization of amniotic bands attaching to the fetus, restriction of motion, constriction rings on extremities, and digital amputation with syndactyly are diagnostic features
• 3D and 4D ultrasound improve sensitivity of prenatal diagnosis
• MRI can provide more detailed characterization

Treatment

Conservative (Observation)

• Shallow, incomplete creases with no distal lymphedema - surgical intervention usually unnecessary except for cosmetic reasons
• Creases should be observed as "baby fat" is lost (may improve in appearance naturally)

Surgical

• Excise down to normal tissue and close with multiple Z-plasty procedures
• If the ring completely encircles the part: staged excision is safer
  • First operation: excise only one half (volar half) of the groove with Z-plasty closure
  • Second operation: 2-3 months later to address the remaining half
  • Splinting maintained for 2-3 weeks; sutures removed at 10-14 days
• Lymphedema and cyanosis typically improve gradually after release
• Simple excision with direct closure combined with limited Z-plasty is an alternative to traditional Z-plasty alone

Figure 85.78B - Z-plasty closure after constriction band excision (Campbell's Operative Orthopaedics, 15th Ed.)

• Early syndactyly reconstruction is essential - all fingertips frequently are bound together, causing permanent deformity if not treated early
• Release of border digits (index and small finger) done within the first 6 months of life
• Release of central digits when the child is approximately 18 months old
• PIP joint stiffness is common after syndactyly release

• Lengthening by osteotomy and distraction
• Shortened thumb may require web space deepening or the Søiland method (adding a shortened index finger "on top" to lengthen the thumb)

Summary

• Campbell's Operative Orthopaedics, 15th Ed., 2026; Miller's Review of Orthopaedics, 9th Ed.; The Developing Human - Clinically Oriented Embryology

Cleft Hand Deformity (Ectrodactyly / Central Longitudinal Deficiency)

Definition and Names

• Ectrodactyly (Greek: "ektroma" = abortion + "daktylos" = finger)
• Split-hand malformation
• Lobster claw hand
• Crab claw hand
• Central longitudinal deficiency (ICD-10: Q68.1)

Clinical Appearance

Fig. 85.63 - Typical bilateral cleft hand with central V-shaped cleft (Campbell's Operative Orthopaedics, 15th Ed.)

Fig. 85.64 - Atypical cleft hand (U-shaped), leaving only thumb and little finger (Campbell's Operative Orthopaedics, 15th Ed.)

Types: Typical vs. Atypical

Pathophysiology

1. Apical Ectodermal Ridge (AER) defect - A wedge-shaped defect in the apical ectodermal ridge of the limb bud during the 5th-6th week of development prevents normal central digital ray formation. This distinguishes cleft hand from symbrachydactyly, which results from primary failure of the underlying bone (hence symbrachydactyly retains small terminal remnants, while pure cleft hand does not).
2. Centripetal suppression theory (Maisels) - Milder deformities have only a simple cleft without significant tissue loss; as severity increases, central ray is lost first, followed by loss of radial rays, and eventually all rays.
3. Association with central polydactyly - Cleft hand and central polydactyly can co-exist, emphasizing the developmental complexity. A rare ulnar-sided cleft hand has also been described (clefting between ring and small, or long and small fingers).
4. Genetics:
   • Most typical cleft hands: autosomal dominant, incomplete penetrance
   • Split-hand/split-foot (SHSF) syndrome: autosomal dominant, ~70% penetrance
   • Many cases are sporadic
   • Associated gene loci: 7q21 (DLX5/DLX6 region), 10q24, 2q31

Classification

Manske and Halikis Classification (most widely used clinically)

OMT Numerical Classification

• Group 0: All central bones present
• Group 1: One ray involved
• Group 2: Two rays involved
• Group 3: Three rays involved Each group is further divided into subgroups by degree of finger involvement.

Radiographic Features

• Transversely oriented bones (delta metacarpals) may be present within the cleft - these will progressively widen the cleft with growth if not removed
• Delta phalanx may be seen
• Two metacarpals supporting one digit, or a split metacarpal supporting two digits
• Metacarpal/phalangeal divergence angle between index and ring fingers should be measured for surgical planning
• Carpal coalition present in older children

Associated Anomalies

• Cleft foot (split-foot)
• Clubfoot, calcaneovalgus, cavovarus foot
• Bilateral absence of the tibia
• Bilateral hip dislocation, short femur, hypoplastic patella
• Short humerus, absent ulna, radioulnar synostosis, elbow synostosis

• Cleft lip/palate
• Deviated nasal septum
• Congenital ptosis, cataracts

• Congenital heart disease
• Imperforate anus
• Deafness
• Anonychia (absent nails)
• Genitourinary anomalies
• Hypoplasia or pseudoarthrosis of the clavicle, absent pectoralis major

• Split-Hand/Split-Foot (SHSF) syndrome - most common; autosomal dominant
• EEC syndrome - Ectrodactyly + Ectodermal Dysplasia + Cleft lip/palate
• Cornelia de Lange syndrome, Fanconi pancytopenia

Function

Treatment

Non-operative

• No effective conservative management exists
• Prostheses have largely been abandoned - even severe bilateral deformities allow significant adaptive function, and prostheses are used only occasionally for cosmesis on request

Indications for Surgery

1. Cleft closure (cosmesis and function)
2. Syndactyly release (especially between digits of unequal length)
3. Narrowed first web space - the most important functional indication
4. Transverse/deforming bony elements - these will progressively widen the cleft during growth; must be removed
5. Absent or hypoplastic thumb reconstruction
6. Delta phalanx correction

Goals of Surgery

• Primary: Achieve good pinch and grasp
• Secondary: Acceptable cosmesis
• Surgery should maintain or improve function; never sacrifice function for appearance

Timing and Sequence

1. Syndactyly release - border digits first (by 6 months of age), central digits by 18 months
2. After 6-month recovery: cleft closure alone, or cleft closure combined with first web deepening
3. For cleft closure with first web deepening: the index metacarpal can be transferred to the long metacarpal position

Key Surgical Techniques

• Snow-Littler procedure - classic technique for cleft closure with first web space deepening
• Miura and Komada technique - less technically demanding, comparable results, fewer complications; 20-year follow-up shows long-term functional success
• Ueba technique - for palmar cleft with absent long finger, especially when combined with narrow thumb web
• Upton-Taghinia technique - simple incision separating glabrous from dorsal skin; avoids complicated dorsal/volar flaps and risk of flap necrosis
• Bipedicle flap/tunneling - index finger tunneled under a bipedicle flap of cleft skin to widen the first web space; good blood supply, no scar within the new web space
• Bony removal - transverse bones blocking cleft closure removed sparingly (excess removal weakens palm and risks cleft recurrence)

For the Atypical Pattern (Symbrachydactyly type)

• Deepening of palm for grasp
• Osteotomies of metacarpals for better opposition
• Tendon transfers for hypoplastic digits
• Single-stage toe-to-hand transfer for the one-digit hand (occasionally)

Worse outcomes associated with:

• Preoperative first web space narrowing
• Postoperative index MCP joint abnormalities

Madelung Deformity

Definition and History

X-Ray Appearance

Fig. 85.15 - Bilateral Madelung deformity: underdevelopment of the volar-ulnar distal radius, increased radial inclination, and proximal immigration of the lunate (Campbell's Operative Orthopaedics, 15th Ed.)

Pathophysiology

The Core Mechanism

• Volar and ulnar bowing of the radius
• Increased radial inclination (ulnar tilt of the articular surface)
• Volar tilt of the lunate facet and scaphoid facet
• The ulna continues to grow straight - leading to dorsal prominence of the distal ulnar head
• Triangulation of the carpus - the lunate migrates proximally into the widened gap between radius and ulna

Role of the Vickers Ligament

• Tethers the lunate to the distal radius proximal to the physis
• Acts as a physical tether that impedes growth of the volar-ulnar physis
• Is the primary deforming force in most cases
• A second anomalous radiotriquetral ligament has also recently been identified in many cases

Timing

Demographics and Associations

• Female predominance: affects girls 4 times more than boys
• Usually bilateral (bilateral deformities are often more severe at presentation)
• If bilateral deformity + short stature: suspect Leri-Weill dyschondrosteosis
• Family history often present

Etiology and Classification (Vender & Watson)

Other conditions producing Madelung-like deformity:

• Mucopolysaccharidosis
• Turner syndrome
• Achondroplasia
• Multiple hereditary exostoses
• Multiple epiphyseal dysplasia
• Ollier disease (dyschondroplasia)
• Prior infection or juvenile chronic arthritis

Genetics: SHOX Gene

• Mild short stature
• Shortness of the middle segments of upper and lower extremities (mesomelia)
• Madelung deformity

Clinical Features

• Deformity usually manifests in late childhood or early adolescence
• Decreased wrist motion (particularly wrist extension and supination)
• Minimal to moderate pain - from ulnocarpal impingement
• Prominent dorsal distal ulna (bayonet deformity appearance)
• Volar displacement of the hand relative to the forearm
• As growth occurs, the deformity worsens in appearance

Radiographic Findings (Table 85.8)

Treatment

Fig. 85.16 - Surgical decision algorithm for Madelung deformity (Farr et al., J Hand Surg Eur Vol 2023; adapted in Campbell's Operative Orthopaedics, 15th Ed.)

Conservative (Non-operative)

• Indicated for: mild symptoms, mature patient with cosmetic concerns only
• Oral NSAIDs, activity modification, wrist splinting
• Serial radiographs every 6 months until skeletal maturity
• Most children have minimal pain and excellent function - non-operative approach is warranted initially

Surgical Treatment

In Skeletally IMMATURE Patients

• First-line for young patients with growth remaining
• The anomalous Vickers ligament is released from its radial attachment
• Combined with physeal bar resection and fat interposition to allow the physis to resume growth
• Guided growth (hemiepiphysiodesis) can augment the procedure
• Technique (Vickers-Nielsen):
  1. Volar transverse incision 1.5 cm proximal to the wrist crease
  2. Protect median nerve and radial artery
  3. Approach radial to the flexor tendons to the pronator quadratus
  4. Longitudinal osteotomy in the radius ~5 mm from the radioulnar joint
  5. Reflect the small volar-ulnar radial fragment ulnarward
  6. Identify and excise the physeal bar; interpose fat
  7. Release the Vickers ligament from its radial attachment

• Preferred for immature patients with moderate to severe existing deformity
• Radial osteotomy can be closing or opening wedge as needed
• Dome osteotomy: provides better volar coverage of the lunate and corrects positive ulnar variance; combined with Vickers ligament release gives best long-term results

• For patients over age 10 years
• Prevents progressive ulnar overgrowth and may avoid later ulnar shortening

In Skeletally MATURE Patients

• Distal radius corrective osteotomy (dome or wedge) + ulnar shortening osteotomy
• Darrach procedure (distal ulnar head resection) - with radial osteotomy
• Sauvé-Kapandji procedure - DRUJ arthrodesis with a proximal ulnar osteotomy (creates a pseudarthrosis above the fusion)
• Watson balanced radial osteotomies with matched ulnar resection - preserves radial length
• Radial osteotomy with callus distraction using external fixator (for severe cases)
• Radioscapholunate arthrodesis with neo-DRUJ - for severely abnormal sigmoid notch (experimental)
• Distal radioulnar arthroplasty

Summary

• Campbell's Operative Orthopaedics, 15th Ed. (2026); Grainger & Allison's Diagnostic Radiology
• Most recent review: Madelung Deformity: A Current Concepts Review (Taleghani et al., J Hand Surg Am, Feb 2026 - PMID: 41686103)