Rupture of the scapholunate ligament is the first event in any sequence of perilunar ligament ruptures. It is the most common pattern of wrist instability.
Its characteristics are the dissociation of the scaphoid and the lunate, with flexion of the scaphoid, and extension of the lunate.
The reconstruction of rotational stability between the scaphoid and the lunate is the key to restoring normal wrist kinematics.
Two joystick K-wires are inserted into the scaphoid and the lunate.
They are used to reduce the scapholunate joint.
In most of the cases, the SL ligament is avulsed from the scaphoid, and still in contact with the lunate.
The avulsion site is debrided for better contact and healing.
A suture anchor is inserted into the debrided area of the avulsion.
The suture anchor must be placed in position slightly oblique to resist rotational forces between both bones (the scaphoid should be pulled from flexion, or the lunate from extension).
The anchor is placed distally in the scaphoid, or proximally in the lunate.
Often, one anchor will be sufficient, but occasionally two anchors will be needed.
The suture is inserted into the ligament proximally when it is anchored in the lunate, and distally when it is anchored in the scaphoid.
If bone anchors are not available, the avulsed ligament is attached using sutures which are passed through small tunnels drilled into the proximal pole of the scaphoid, as illustrated.
Use the two joysticks to extend the scaphoid, flex the lunate, and then close the gap.
A pointed reduction clamp helps to secure the reduction temporarily.
Confirm reduction using image intensification.
Both bones are secured in position by transfixation with two K-wires inserted percutaneously from scaphoid to lunate.
Again, confirm the position of both wires using image intensification.
Afterwards, the sutures are tied to the bone anchor.
If the ligament is torn in the mid-substance, directly repair with resorbable sutures.
Cut the K-wires and bend them so they rest underneath the skin.
Immobilize the wrist with a well-padded below-elbow splint for 2 weeks
While the patient is in bed, use pillows to keep the hand elevated above the level of the heart to reduce swelling.
For ambulant patients, put the arm in a sling and elevate to above the heart.
After 14 days remove the sutures, check the skin over the K-wires, and apply a below-elbow scaphoid cast.
Immediately postoperatively begin active, controlled digital range-of-motion exercises.
Load bearing through the splinted wrist must be avoided. The cast is changed and the skin regularly checked every 2 weeks in the outpatient clinic.
Cast immobilization is usually continued until 8 weeks postoperatively. At that time, an x-ray of the wrist is mandatory to assess bony healing and the position of the carpal bones. If bony healing can not be assessed from the plain radiographs, a CT scan is recommended.
The K-wires that are securing additional ligament lesions are removed at 8 weeks with appropriate pain control.
When bony union is confirmed, the patient can start with range-of-motion exercises of the wrist. A removable wrist splint may be used for patient comfort for a few more weeks.
The importance of mobilization must be emphasized to the patient and rehabilitation should be supervised by a physical therapist.