Most of the patients with perilunate dislocations are young males.
The injuries which lead to a progressive disruption of most capsular and ligamentous connections of the lunate result in perilunate dislocations.
The most common pattern of perilunate instability is the transscaphoid perilunate fracture dislocation.
Presentation of Perilunate Dislocation
The patient presents pain, swelling, and deformity . The examination may reveal deformity and disruption of distal and proximmal row. Neural examination may reveal an injury to median or ulnar nerve.
Imaging of Perilunate Dislocation
A grossly altered intercarpal relationship indicated by broken Gilula arcs , triangular shaped lunate [due to rotation] on AP view and palmar deviation of thelunate on lateral view are findings that suggest perilunate dislocation.
CT, MRI and arthroscopy can determine true extent of injury.
Classification of Perilunate Dislocations
Perilunate dislocation is of two types
Lesser-arc perilunate dislocations – Pure ligamentous injuries around the lunate.
Greater-arc perilunate dislocations – Fracture of one or more of the bones around the lunate.
Treatment of Perilunate Dislocations
Acute and Reducible Dislocations,
Closed reduction Tavernier’s maneuver under general or regional and cast immobilization for 12 weeks.
The traction is applied to the wrist and it is brought in extension.The surgeon’s thumb is placed on the lunate volarly to prevent creating a volar lunate dislocation. Then,the wrist is flexed with traction still maintained.
This should result in an audible or palpable clunk signifying reduction of the capitate on the lunate and restoration of normal bony alignment. .
Some authors recommend percutaneous K-wire fixation to stabilize the carpus after closed reduction to reduce chances of loss of reduction later on.
Kwire fixation also enhances the and enhances the healing capability of the intrinsic ligaments by maintaining complete immobility
Acute and Irreducible Dislocations
Those dislocations for which closed reduction cannot be carried out, open repair is indicated
Chronic Perilunate Dislocations
Open reductiona and fixation should be done for the cases if the carpal alignment is feasible [Can be checked under traction xrays].
Generally, injuries seen within 3 to 6 months are still potentially treatable by open reduction because cartilage changes have not set in.
In late presentations where open reduction and internal fixation is not going to help, a salvage procedure like proximal row carpectomy or a total wrist arthrodesis [fusion] is done.
Greater Arc Injuries
This involves combination of fracture dislocation and are best treated by open reduction and internal fixation with Kwire or Herbert screw.
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