Hyperextension at PIPJ
Flexion at DIPJ
Flexion at MCPJ
Possible causes of swan-neck deformity may involve any of the joints.
Site wise cause –
Synovitis of joint à leading to attenuation of volar plates and TRL (Transverse retinacular ligament) à allowing dorsal translocation of lateral bands & Destruction of FDS insertion àLeading to hyperextension of PIPJ
Hyperextension at PIPJ leads to tightening of FDP tendon and loss of tension in lateral bands à leading to DIPJ flexion
Over time adhesions develops leading to fixed deformity
Synovitis of MCPJ à causes weakening of insertion of long extension on proximal phalanx à causing force to be transmitted to base of proximal phalanx à leading to PIPJ hyperextension
Synovitis also leads to weakening of volar plates à cause subluxation of MCPJ – leading to adhesion and later shortening of intrinsic muscles – further contributing to PIPJ hyperextension.
Rupture of extensor tendon (due to trauma or synovitis) – leads to proximal migration and relaxation of lateral bands.
Extensor power is then concentrated on central slip à resulting in PIPJ hyperextension and SND
Synovitis causes – carpal collapse, carpal supination & ulnar tranlocation
Carpal collapse – leads to relative lengthening of long flexors and extensors à allowing intrinsics to overpower their action à leading to hyperextension at PIPJ and then to SND
|DIPJ||Mallet finger (rupture of extensor tendon)|
|PIPJ||Volar plate laxity |
Dorsal migration of TRL
|MCPJ||MP joint volar subluxation |
Intrinsic muscle tightness
Weakening of insertion of long extensors on proximal phalanx
|Wrist joint||Carpal collapse|
Feldon et al
Type I – PIPJ – flexible in all position
Type II – PIPJ – flexion limited in certain position
Type III – limited flexion in all positions
Type IV – stiff joint with poor radiographic appearance
Nalebuff classification –
Type I – full PIPJ flexibility without intrinsic tightness
Type II – PIPJ flexible but with P joint volar subluxation and associated intrinsic tightness
Type III – motion of PIPJ limited by extensor mechanism but with radiographic preservation of joint surface
Type IV – stiff PIP joint with intrarticular joint destruction
Type I –
Can be managed non-operatively – by Splinting with Silver ring
Operative management –
If primary pathology at DIPJ – Mallet finger – DIPJ arthrodesis
If pathology at PIPJ level –
Flexor tenodesis @ PIPJ
Distally based slip of FDS
Littler’s ORL reconstruction
Free tendon graft (Spiral ORL reconstruction)
Type II –
In addition to above also require –
MCPJ reconstruction or MP implant arthroplasty
Type III –
In addition to above – PIPJ manipulation is required
Lateral band release
Central slip release or lengthening
PIPJ dorsal capsulotomy
Type IV –
PIPJ fusion or arthroplasty
Summary of treatment options for SND
|Type||Site wise treatment required|
|I||Dermodesis FDS sling (flexor tenodesis) Littler’s ORL reconstruction||Fusion|
|II||Intrinsic release||As for type I||Fusion|
|III||As for type I Plus MCPJ reconstruction as needed||As for type I Plus PIPJ manipulation(dorsal capsulotomy) Skin release Lateral band release Central slip release or lengthening Check flexor tendons||Fusion|
|IV||As for type III||As for type III Plus Arthroplasty or fusion||Fusion|
ORL (Oblique Retinacular ligament) –
ORL was described by Landsmeer hence a/k/a Landsmeer ligament
Originates – from flexor sheath at volar aspect of PIP joint and
Inserts – dorsally into terminal tendon
ORL thus connects flexor mechanism to extensor mechanism.
It tightens during PIPJ extension and results in DIPJ extension
ORL reconstruction –
Littler’s ORL reconstruction –
Ulnar lateral band is divided proximally and
Re-routed palmar to axis of PIPJ rotation using Cleland ligament as fulcrum and
Secured to flexor tendon sheath
Lateral band now act as ORL
Thompson’s Spiral ORL reconstruction –
Free tendon graft is used.
Tendon graft is placed through gauzed hole in distal phalanx and directed in spiral fashion over middle phalanx, deep to neurovascular bundle, over the flexor sheath and transversely through base of proximal phalanx
Graft tension is adjusted with PIPJ and DIPJ in neutral extension.
Proximal end is secured with button or hemoclips or both.
Active motion is allowed 3 weeks post-op.
Kleimen modification of Spiral ORL reconstruction –
Axial K-wire used to keep DIP in neutral and
Oblique K-wire to keep PIPJ in 10-15° of flexion.
Proximal pin removed at 3 weeks
DIP pin removed at 4.5 weeks
Followed by splinting of DIP for 1.5 weeks in extension
Secured the tendon graft to dorsal distal phalanx with 4-0 Bunnell steel pull-out wire
Proximal juncture was attached to palmar flexor sheath with non-absorbable suture.
FDS sling –
Distally based slip of FDS can be sutured to leading edge of A1 pulley or can be secured to bone at the base of proximal phalanx.
Lateral band release –
Lateral band release done through two parallel incision and released from central slip and now are slide volar to the condyle.
Central slip tenotomy or lengthening –
Relies on mature terminal tendon
Procedure is done usually 6-12 months after the injury.
The procedure results in proximal migration of extensor mechanism and thus correct “the slack” induced by elongation at the terminal tendon.
Finger is exposed by midlateral incision centered over PIPJ
Transverse retinacular ligament is incised
Freer elevator is inserted under the extensor mechanism proximal to the central slip and underneath the lateral bands distal to central slip.
The insertion of central slip is visualized under the extensor mechanism, the insertion is divided by sliding a scalpel from proximal to distal underneath the extensor mechanism and active extension of DIP joint attempted.
A dorsal view of extensor mechanism will not reveal any discontinuity.
This technique can correct extension lag of DIPJ up to 35°.
Triangular ligament is not damaged and hence boutonneire deformity will not occur.