- Flexion at PIPJ
- Extension at DIPJ
- Extension at MCPJ
Pathology is at PIPJ alone.
It’s more of an aesthetic problem than functional – as the patient can still make fist and grasp objects
Deformity is characterized by –
Central slip dysfunction – either due to injury or attenuation secondary to synovitis (from inflammatory disorder such as RA)
Triangular ligament stretches over time – allowing the lateral bands to migrate volar to the PIPJ axis of rotation so that they become flexor of PIPJ and extension of DIPJ.
Ruptured central slip also allows the force from the lumbricals and interossei to be transmitted directly to distal phalanx resulting in DIPJ extension.
Nalebuff’s classification –
Stage I – Mild – PIP extension lag that is passively correctable with some DIPJ flexion limitation.
Stage II – moderate – PIPJ flexion deformity >40 ° that may or may not be passively correctable
Stage III – Fixed – Fixed PIPJ flexion deformity with joint destruction
Burton’s classification –
Stage I – supple, passively correctable deformity
Stage II – fixed contracture with contracted lateral bands
Stage III – fixed contracture with joint fibrosis, collateral ligament and volar plate contracture
Stage IV – stage III plus PIPJ arthritis
Passively correctable deformity is managed by –
Splinting to achieve full PIP joint extension – by means of serial casting, splinting, or dynamic splinting. After full PIP joint extension is achieved it is maintained in this position for at least for 6 to 12 months.
During whole of this time DIP joint active and passive flexion exercise is done.
If full passive PIP joint extension is not achieved through non-operative means then – surgical release of contracted collateral bands or volar capsulotomy are done.
If full passive PIP joint extension is achieved but there is active extension lag then – there are multiple surgical procedure for correction.
Fixed deformities with joint destruction are managed by – PIP joint arthrodesis
Curtis staged reconstruction of boutonneire deformity –
These operation relies on full passive mobility of PIPJ preoperatively.
Surgery is performed under local anesthesia.
After release at each stage, PIPJ is actively extended by patient and surgery proceeds to next stage if full extension is not achieved.
Stage I –
Lazy “S” incision made centered over PIPJ laterally.
Transverse retinacular ligament is freed distally and proximally and
Tenolysis of extensor tendon performed.
If full extension is achieved then the operation stops
Stage II –
If full extension is not achieved then TRL is transected, allowing the lateral bands to swing dorsally.
If full extension is achieved after this then the MCPJ is splinted in 70° of flexion and PIPJ & DIPJ splinted in 0° for 1 week followed by dynamic PIPJ splinting.
Stage III –
If there is still 20-degrees or lesser extensor lag after stage II then – distal Fowler tenotomy is performed.
A “step-cut” lengthening of the lateral bands to prevent a mallet finger. Or the extensor mechanism can be obliquely transected just distal to the triangular ligament.
If full extension is present, then operation stops.
Stage IV –
If extensor lag after stage II is more than 20 degrees then step III can be skipped and operation proceeds directly to stage IV.
The central tendon is dissected free and advanced about 4 to 6 mm into a drill hole in the dorsal base of the middle phalanx. The lateral bands, now slack, are loosely sutured to central tendon.
After surgical correction –
PIPJ is stabilized in extension with K-wire.
DIPJ is kept free and active ROM exercises is ordered.
PIP joint ROM exercises begun after 3 weeks with intermittent splinting
Curtis stage reconstruction –
- Stage I – Tenolysis of extensor mechanism
- Stage II – Release of TRL
- Stage III – Fowler tenotomy of distal extensors
- Stage IV – Central slip reconstruction
Acute central slip injury –
Central slip rupture alone will not cause boutonneire deformity and hence acute central slip injury does not present as boutonneire deformity.
In acute stage, Elson test should be done to diagnose central slip injury in suspected cases.
If lateral bands are also cut over PIPJ or if triangular ligament is also injured allowing volar migration of lateral band then classical boutonneire deformity occurs with PIPJ extensor lag.
Untreated central slip disruption usually present after 2-3 weeks as triangular ligament stretches and lateral band migrate volarly.
Treatment of acute central slip injury –
Splinting or pinning PIPJ in full extension for 6 weeks with active DIPJ flexion exercise hourly
Central slip injury with avulsion of piece of bone.
Small piece of bone and minimally displaced – splinting for 6 weeks
Large piece of bone and displaced >2mm – K-wire fixation
Small or comminuted fragment – excision of fragment and tendon repaired directly to bone using pull-out suture or suture anchors.
“Pseudoboutonneire” deformity –
PIPJ flexion contracture without DIPJ extension
Cause is usually due to collateral ligament injury typically following PIPJ hyperextension injury – resulting in collateral ligament and volar plate scarring.
Lateral bands and central slip remains competent.
Treatment – is aimed at decreasing PIPJ flexion contracture by dynamic splinting or serial static casting.
Terminal tendon tenotomy (Distal Fowler or Dolphin tenotomy) –
Surgery aims at operatively creating a “mallet finger” – this would decrease the extensor tone at the DIP joint thus allowing DIPJ flexion. This procedure will also result in proximal migration of extensor mechanism and hence increasing the extensor tension at PIP joint.
This procedure is designed for patient with – full passive PIPJ extension.
It is contraindicated in patient with a fixed PIP joint flexion deformity.
A dorsal incision is made over middle phalanx and the extensor mechanism is divided transversely over the junction of its middle and proximal thirds, distal to the triangular ligament.