Educational video describing the Boutonniere deformity of the fingers. Also describing conditions of Swan Neck and Mallet finger deformities.
Deformity is characterize by PIP flexion and DIP extension. Injury to the extensor tendon or central slip usually prevents the finger from active extension.
Anatomy
What are the differences between Boutonneire and other deformities of the finger?
Mallet finger
Rupture or avulsion of the terminal extensor tendon.
Treatment:
•Immobilization of the DIP joint in extension. Keep the PIP joint free.
•Surgery by pinning if subluxation of the joint or avulsion fragment is more than 50%.
Swan neck
Deformity and casues
•Mallet (DIP)
•Volar plate laxity or injury (PIP)
•Subluxation (MP)
Boutonniere
Extenrsor tendon injury. Three components:
1-Central slip rupture
2-Traingular ligament attenuation
3-Lateral band volar migration
Stages to Boutonniere:
1-Injury to the central slip will lead to lack of extension of the PIP
2-Triangular ligament, lateral band separation and volar migration will casue flexion force on the PIP and extension force on the DIP
3-Retinacular ligaments contracture
4-PIP and DIP capsular contracture
Clinical examination
•The extensor tendon of the finger splits into the lateral bands.
•The lateral band then come together and insert into the base of the distal phalanx.
•The central slip insets into the base of the middle phalanx. If the central slip becomes ruptured, the lateral bands will slip down to the volar position.
Elson’s test
•Used to determine possible tear of the central slip before the deformity is evident.
•Patient is asked to curl the affected finger around the edge of a table (the PIP is bent 90 degrees over the edge of the table).
•The examiner then places their finger over the middle phalanx.
•The patient is then asked to extend the finger.
•If the central slip is intact, the examiner will be able to feel the tension of the finger being extended.
•With a ruptured central slip, the examiner will not feel tension, as the patient will be unable to extend the PIP joint.
Treatment
Acute Boutonneire
•Static splint of PIP for 6 weeks
•Used for acute injuries less than 4 weeks
•DIP and MP joints should remain free.
Acute open repair of boutonniere: open injury requires surgical repair
Chronic boutonniere: more than 2 months after injury
Reconstruction of the extensor mechanism. Use splint before surgical release. Full passive range of motion of the PIP and DIP is needed before surgery.
Bad prognosis if:
•Patient is more than 45 years of age
•Associated fracture
•Fixed PIP contracture
•Prior surgery
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