What is a Perilunate Dislocation?
Perilunate dislocations, and perilunate fracture dislocations, involve traumatic rupture of the radioscaphocapitate (RSC) ligament, the scapholunate interosseous (SLI) ligament, and the lunotriquetral interosseous (LTI) ligament.
Fractures of the radial styloid, the scaphoid, the trapezium, the capitate, and the triquetrum may also be associated with the dorsal or the volar perilunate dislocation.
Characteristics and Clinical Presentation of Perilunate Dislocation
Many patients present with acute injury resulting from a fall onto a dorsiflexed wrist. Volar skin lacerations could represent an open dislocation or fracture dislocation. This injury presents with obvious deformities, such as marked swelling.
Patients may complain of a sprained wrist. In dorsal perilunate dislocations, the carpus is dislocated dorsally, and the radius is prominent volarly. Lunate dislocations present with prominent volar lunate.
Because of the high-energy nature of perilunate fracture dislocations, Dr. Mark Pruzansky and Dr. Jason Pruzansky perform a careful, thorough trauma survey with assessment for associated injuries of the hand, wrist, and elbow.
Causes of Perilunate Dislocation
Most perilunate dislocations and perilunate fracture dislocations typically young adults who are exposed to high-energy trauma. In these injuries, the fall generally results in the wrist being axially loaded by the body.
The mechanism of perilunate dislocations has been described as a four-stage process, as follows:
- First stage: the RSC ligament and the SLI rupture
- Second stage: dislocation of the capitolunate joint occurs as the injury progresses through the space of Poirier
- Third stage: the LTI ligament ruptures
- Fourth stage: the lunate becomes dislocated
Injuries Associated with Perilunate Dislocation
Damage to the median nerve is the most common associated injury in lunate and perilunate dislocations of the wrist. Volar skin lacerations may represent open dislocation or fracture dislocation and can become ischemic from pressure by the volar radius.
Patients may present with arterial compromise or established compartment syndromes.
Getting a Diagnosis for Perilunate Dislocations
Acute PA, lateral, and oblique radiographs over the carpus without splint materials or dressings are required for accurate diagnosis of carpus trauma in patients with a significant wrist injury.
Computed tomography (CT) can be helpful for defining scaphoid fractures, capitate fractures, radial styloid fractures, and triquetral fractures.
Differential Diagnosis for Perilunate Dislocations
Lunate dislocation can mimic a perilunate dislocation, especially on AP projection. In order to not confuse the two, please note:
- in a lunate dislocation, the radiolunate articulation is disrupted and the lunate is dislocated in a palmar direction
- in a perilunate dislocation, the radiolunate articulation is maintained
Treatment Options for Perilunate Dislocations
Perilunate dislocations and perilunate fracture dislocations must be corrected with open reduction and internal fixation (ORIF) immediately following the injury.
A perilunate dislocation should be reduced as soon as possible. Fractures associated with perilunate dislocations may require small compression screws or percutaneous pins.
Nonsurgical Treatments for Perilunate Dislocation
If definitive surgical management of the perilunate dislocation or fracture dislocation is delayed, closed management of the radiocarpal and midcarpal joints must proceed on an emergency basis. The wrist should be splinted in a well-padded plaster mold to prevent injury progression and control pain.
Surgical Treatment Options for Perilunate Dislocation
Depending on the severity of the dislocation, Dr. Mark Pruzansky and Dr. Jason Pruzansky may determine that surgery is the best option. In this case, there are several surgical options:
- Closed reduction and casting
- Closed reduction and percutaneous pin fixation
- Open reduction and open ligamentous repair with internal fixation or with percutaneous pin fixation
The surgical treatment of choice is open reduction and ligamentous repair with percutaneous pin fixation. Internal fixation is preferred in instances of distal radial styloid fracture or carpal bone fracture.
The splint is removed 3-5 days after surgery. At 10-14 days, the sutures are removed, and a short arm cast is applied.
Complications of Perilunate Dislocations
Left untreated, these injuries can cause loss of motion and median nerve dysfunction. Unreduced dislocations of the carpus have the potential for skin ischemic pressure necrosis.
Patients may present with stiffness, weakness, and osteoarthritis. Latent carpal instability presents with the development of carpal instability dissociative (CID) in either the volar intercalated segment instability (VISI) form (CID-VISI) or the dorsal intercalated segment instability (DISI) form (CID-DISI).
Other complications include ulnar translocation of the carpus and combination of dissociative and nondissociative instability, creating carpal instability complex.
A cast is maintained for 3 months following surgical intervention. Periodic radiographs ensure maintenance of midcarpal and radiocarpal reduction. Splinting is recommended for 6 months. Full activity is usually not renewed until 8 months after surgery.
The outcomes of perilunate dislocations and perilunate fracture dislocations are best when emergency reduction of the carpus is performed, followed by accurate open reduction and internal fixation (ORIF).
Capo et al reported reasonable and functional clinical results after treatment of perilunate fracture dislocations with a combined volar-dorsal approach.
If You Believe You Have Perilunate Dislocation, Contact HandSport Surgery Institute
Please contact us as soon as possible to schedule an appointment with our talented team. People experiencing perilunate dislocation should be evaluated to try and prevent further injury and mobility issues.
If you have been injured, it’s important to be evaluated by a highly skilled professional. Call Drs. Mark and Jason Pruzansky at 212-249-8700 to schedule an appointment, obtain an accurate diagnosis, and start to restore comfort to your wrist.