Metacarpo-phalyngeal joint dislocation.pptx

Metacarpo-phalyngeal joint dislocation

1. Metacarpo-phalyngeal joint dislocation Dr JUNAID JAVED MS orthopaedic surgery

2. Summary MCP Dislocations are a dislocation of the metacarpophalangeal joint, usually dorsal, caused by a fall and hyperextension of the MCP joint. Diagnosis can be made clinically and is confirmed by orthogonal radiographs. Treatment is closed reduction unless soft tissue interposition blocks reduction, in which case open reduction is indicated.

3. Anatomic location dorsal dislocations  are most common index finger  is most commonly involved thumb is second most common digit involved

4. Etiology Pathophysiology mechanism of injury usually a fall on outstretched hand leading to  hyperextension of MCP joint leads to avulsion of the volar plate from metacarpal neck

5. Anatomy

6. Classification Anatomic classification of MCP dislocation Volar Results from hyperextension or hyperflexion injury Dorsal Most commonResults from hyperextension injury

7. Complexity of MCP dislocation Simple (subluxation) No interposition of volar plate and/or sesamoid Base of proximal phalanx remains in contact with the metacarpal head Complex (complete) Interposition of volar plate and/or sesamoids Metacarpal head becomes entrapped by     -displaced natatory ligaments distally     -superficial transverse metacarpal ligament proximally Kaplan's lesion (rare)     -most common in index finger     -metacarpal head buttonholes into palm ( volarly )     -volar plate is interposed between base of proximal phalanx and metacarpal head

8. Presentation Physical exam deformity seen on inspection depends on type of dislocation dorsal dislocation simple hyperextension of proximal phalanx  on metacarpal head flexion of PIP joint complex bayonet positioning of proximal phalanx  (dorsal to metacarpal shaft) skin dimpling  in proximal palmar crease volar dislocation extensor lag present dorsal skin depression  found proximal to base of proximal phalanx

9. Imaging Radiographs recommended views AP lateral best view to see dislocation   oblique findings complex dislocation joint space widening  may indicate interposition of volar plate   entrapment of sesamoid in MCP joint is diagnostic of complex dislocation

10. Nonoperative closed reduction indications simple dislocations Operative open reduction                indications complex dislocations

11. Complications Joint stiffness due to soft tissue trauma at time of injury or prolonged immobilization Post-traumatic arthritis or osteonecrosis due to repeated attempts at closed reduction, prolonged dislocation, traumatic open reduction Premature physeal closure rare