Scapholunate Ligament Rupture
Some of the content in this handout is reproduced with permission from Dr Stuart Myers at www.myhand.com.au
The wrist is a complicated combination of bones and ligaments.
There is a radiocarpal and midcarpal joint that are responsible for allowing the wrist to move up & down & side-to-side.
(Flexion / Extension / Radial and Ulnar Deviation)
There are many ligaments in the wrist.
Ligaments are strong soft tissues that connect bones to each other.
There are two types of ligaments
- Ligaments connecting the small bones of the wrist together (intrinsic) and
- Thickenings in the wrist capsule (extrinsic)
The scapholunate ligament is an intrinsic ligament connecting the scaphoid to the lunate.
It is important stabiliser of the wrist to control the movements between the bones.
It is "C" shaped with the back (dorsal) and front (volar) component being the strongest.
The dorsal component of the ligament is the most important.
If the scapholunate ligament is torn there is a loss of the balance of the wrist.
The bones change position and move differently with wrist movement.
There is abnormal contact between the bones which eventually results in wrist arthritis (wear and tear).
The abnormal movement of the wrist can cause a clicking sensation in the wrist.
The scapholunate ligament usually ruptures with trauma - this can occur with a simple fall or with high energy trauma.
The diagnosis is often delayed as the wrist is thought to be only "sprained".Sometimes it can occur as a generalised degeneration of the wrist.
X-Ray - often the signs are very subtle and special "instability" views are required.
Often there is a wider than normal gap between the scaphoid and lunate (Terry Thomas Sign).
The position of the small bones in the wrist changes. Later arthritis develops in the wrist.
MRI - can help with diagnosis.
Arthroscopy - is sometimes required to assess.
The natural history of a scapholunate ligament rupture is to develop arthritis of the wrist in the future.
The difficulty is it is hard to predict how long until this occurs and how symptomatic each individual patient will be.
This is why the management of SL ligament injury can be so varied from surgeon to surgeon.
Arthritis tends to affect the radiocarpal joint first followed by the mid-carpal joint.
If the scapholunate ligament rupture is symptomatic the treatment will depend on the following factors
How long since the injury?
- In acute (new) injuries often the ligament can be repaired. An injury that occured some time ago this may not be possible
Has the position of the bones changed permanently to an abnormal position?
- In a chronic injury (old) the bones change position and there is scarring of the wrist capsule stopping reduction to a normal position
Is there any arthritis in the wrist?
If so where is the arthritis.
Partial tears of the ligament are best diagnosed with an arthroscope. The scapholunate gap can be probed to asses its stability. Partial acute tears can be pinned with fine metal wires until there has been healing.
If the ligament is acutely completely torn an assessment about the ability to repair the ligament needs to be made.
Bone anchors can be used to reattach ligaments pulled off the bone.
The wrist capsule (lining of the joint) is sometimes used to protect the repair. This is called a capsulodesis.
Fine wires are also used to protect the repair.
Generally after surgery the wrist needs to be in a cast for 8 weeks at which stage the wires are removed.
A removable wrist splint is then used for the next 4 weeks.
After this period the wrist is very stiff. It takes several months to regain some range of motion and strength in the wrist.
Generally the range of motion will be less than normal.
If the ligament is not repairable and the bones can be reduced to their normal position I use a ligament reconstruction.
I use half of a tendon (FCR) at the front of the wrist which is transferred to the back of the wrist via a drill hole made in the scaphoid bone.
It is then attached to the lunate (to recreate the SL ligament) and augmented with a capsulodesis. Again wires help hold the bone until healing has occured.
If the bones cannot be reduced to a normal position, or there is arthritis in the wrist, a salvage surgical procedure is required. This may involve removing the scaphoid and fusing the remaining small bones in the wrist (4 corner fusion) or removing the proximal row.