Swan Neck Deformity

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Swan Neck Deformity

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Swan neck deformity. The volar plate is torn,
causing the joint to open abnormally under the
pull of the extensor ligaments.
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Swan-Neck Deformity

• Typically defined as
• proximal interphalangeal (PIP) joint
  hyperextension
• with concurrent distal interphalangeal (DIP)
  joint flexion
• Not necessarily unique to RA but rather an end
  result of muscle and tendon imbalance caused by
  RA.

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Swan-Neck Deformity

• Not necessarily unique to RA but rather an end
  result of muscle and tendon imbalance caused by RA

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Nalebuff Classification1989

• Type I - PIP joints flexible in all positions
• No intrinsic tightness or functional loss
• Type II - PIP joint flexion limited in certain
  positions
• Intrinsic tightness
• Limited PIP motion with extended MCP with ulnar
  deviation
• Type III - PIP joint flexion limited in all
  positions
• Near normal radiograph
• Type IV - PIP joints stiff with poor radiographic
  appearance

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Pathophysiology

• The intercalated joint collapse concept of
  Landsmeer means that collapse of a joint in one
  direction will result in deformity of the next
  distal joint in the opposite direction.
• Z deformity

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Pathophysiology

• In a normal finger, intrinsic muscles serve as
• flexors of the MCP joint
• extensors of the PIP and DIP joints
• By being located volar to the MCP joint axis and
  dorsal to the PIP and DIP joint axes

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Pathophysiology

• Intrinsic tightness increases the flexor pull on
  the MCP joint and hyperextension of PIPJ
• Weak flexor power aggravates this by being
  unable to pull the middle phalanx.
• DIPJ and MCPJ hyperextension follows
• Constant efforts to extend the finger against
  this pull then leads to stretching of the
  collateral ligaments and weakening of the volar
  plate at the PIPJ.

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Pathophysiology

• the lateral bands are constrained in their dorsal
  position with the extensor apparatus migrating
  proximally
• therefore upsetting the flexor-extensor balance,
• The lateral bands in this position act to
  increase the pull of the central slip that
  attaches to the dorsal base of the middle
  phalanx.
• Leading to hyperextension of PIPJ

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Pathophysiology

• The increase of FPL tension resulting from
  hyperextension of the PIP joint leads to a
  reciprocal flexion of the DIP joint.
• DIP mallet deformity also from
• Joint erosion
• Extensor tendon attentuation or rupture
• Progressive disease leads to joint destruction
  and fixed contracture.

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Hashemi-Nejad and Goddard (1994)

• -multidisciplinary approach is best
• -an affected joint will affect other joints
• -early synovectomy is worthwhile after a 6-month
  trial of non-operative treatment
• -tenosynovectomy decreases the risk of tendon
  rupture,
• -the wrist is the key in the RA hand
• -the thumb is a very important source of
  disability
• -silastic MCPJ arthroplasty is successful in
  reducing pain and improving function

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Feldon (1993) lists the aims of surgery in the RA
hand

• 1. pain relief
• 2. functional improvement
• 3. preventing disease progression
• 4. cosmetic improvement
• Note that the presence of a painless deformity
  with minimal function deficit is not an
  indication for surgery.

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Management

• Millender and Nalebuff staging system (1975) is a
  good guideline for identifying treatment options
  in RA

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Principles

• Prevention
• Correct PIPJ hyperextension
• Restore DIPJ extension

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Type1

• Silver ring splint to flex PIPJ
• Volar dermatodesis
• Correction of any MCPJ abnormality first
• Flexor tenosynovectomy (if synovitis is present)
• Flexor tenodesis - FDS slip through A2 pulley
  then looped back to itself
• Retinacular ligament reconstruction
• Release ulnar lateral band proximally and pass
  volar to PIPJ axis ? sheath

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Silver Ring Splint

• Permit active PIP flexion and limit
  hyperextension of the PIP joint

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DIP Fusion

• Difficult and unreliable to restore the extensor
  apparatus at DIP level cause underlying RA
  disease will destroy the repair
• Also secondary arthritis within DIP may make
  attempts to mobilise joint unwise

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Dermadesis

• Used to prevent PIP hyperextension bu creating a
  skin shortage volarly
• Elliptical skin wedge (4-5mm at widest) is
  removed from volar aspect of PIP
• Care not too disturb venous drainage or violate
  the flexor sheath
• Skin closed with PIP in flexion
• Only useful if done in conjunction with other
  procedures ie DIP fusion

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Flexor Tendon Tenodesissublimis sling

• Used as checkrein against hyperextension ie
  restoration of strong volar support
• One slip of FDS is divided 1.5cm proximal to PIP
• This is then separated from its corresponding
  slip bit left attached distally
• With joint at 20-30 degrees the detached slip is
  fixed proximally
• Anchored to thickened margin of sheath, distal
  edge of A2 or Mitek
• Nalebuff did simpler procedure whereby he passed
  split tendon around A1 pulley

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Reticular Ligament Reconstruction

• Credited to Littler
• Ulnar lateral band is freed from extensor
  mechanism proximally but left attached distally
• Passed volar to Clelands fibres to bring it
  volar to axis of PIP
• Band is sutured to the fibrous tendon sheath
  under enough tension to restore DIP extension
  and prevent hyperextension at PIP
• However, in RA may have destruction of terminal
  tendon so no amount of tension applied to the
  relocated tendon will achieve DIP extension

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Type 2

• Looks like Type 1 but PIP movement is limited in
  certain positions related to position of MCPJ
• MCPJ extended/radial deviation then limited
  passive PIP ROM
• MCPJ flexed/ulnar deviated then PIP ROM increased
• As MCPJ subluxates and the intrinsics get tight a
  secondary swan neck develops as a result of
  muscular imbalance
• Not sufficient to restrict PIPJ hyperextension,
  intrinsics must be released plus MCPJ subluxation
  must be corrected /- arthroplasty

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Intrinsic Release

• Photo on camera
• A rhomboid portion of the ulnar extensor
  aponeurosis is then resected
• This procedure resects the lateral band through
  which the abnormally tight intrinsics have caused
  MP flexion and PIP hyperextension

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Type 3

• unlike type 1 2 have significant functional
  disability due to inability to grasp objects
• Not joint destruction but restriction due to
• Extensor mechanism
• Collateral ligaments
• Skin
• First goal is to restore passive ROM
• PIPJ manipulation
• Skin release
• Lateral band mobilisation
• Then correction of deformity after motion restored

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PIPJ Manipulation

• MUA possible up to 80-90 degrees
• Usually in conjunction with intrinsic release,
  arthroplasty or tenosynovectomy

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Skin Release

• Dorsal skin may limit the amount of passive
  flexion that is achieved during manipulation
• Tension minimised with an oblique incision just
  distal to the PIPJ
• Allowing skin edges to spread
• Closes 2-3 weeks by secondary intention
• PHOTO 2112

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Lateral Band Mobilisation

• Lateral bands are displaced dorsally
• Free lateral bands from central slip using 2
  parallel incisions allows flexion without
  releasing lateral bands or lengthening central
  slip
• PHOTO 2113

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Type 4

• Patients with stiff PIPJ and radiographic
  evidence of advanced intra-articular changes
  require salvage procedure
• Fusion or arthroplasty
• PHOTO 2114