A scapholunate ligament injury is one of the most common serious ligament injuries affecting the wrist. The ligament connects the scaphoid and lunate bones and plays an essential role in maintaining normal wrist movement and stability. When this ligament is torn, it can cause pain, weakness, clicking of the wrist and, over time, may lead to arthritis if left untreated.
Mr Robert Farnell is an experienced specialist Consultant Orthopaedic Hand and Wrist Surgeon who has been working in Leeds for over 25 years. He exclusively treats conditions affecting the adult hand and wrist, including wrist ligament injuries, scaphoid fractures, wrist arthritis and complex wrist trauma.
What is the scapholunate ligament?
The wrist is made up of eight small carpal bones which work together to provide both strength and flexibility. These bones are connected by numerous strong ligaments.
One of the most important is the scapholunate ligament. It joins the scaphoid and lunate bones together and helps maintain their normal alignment during wrist movement.
If this ligament tears, the two bones can separate and move abnormally, resulting in pain, weakness and wrist instability.
Figure 1: The scapholunate ligament connecting the scaphoid and lunate bones.
How is the scapholunate ligament injured?
Most scapholunate ligament injuries occur after a fall onto an outstretched hand. Less commonly, they may result from a forceful twisting injury to the wrist.
The mechanism of injury is very similar to that of a scaphoid fracture, which is why the two injuries are sometimes difficult to distinguish during the early stages.
Symptoms of a scapholunate ligament injury
Symptoms depend on whether the injury is recent or longstanding.
Acute injury
- Wrist pain following a fall
- Swelling
- Loss of wrist movement
- Reduced grip strength
- Painful clicking or clunking within the wrist
Chronic injury
- Persistent wrist pain
- Weakness
- Pain after activity
- Clicking or clunking of the wrist
- Background pain caused by secondary arthritis
How is a scapholunate ligament injury diagnosed?
Diagnosis begins with a detailed history and examination.
Mr Farnell will examine the wrist for tenderness over the scapholunate ligament, swelling, reduced movement and signs of instability.
One important clinical examination is the Kirk-Watson test, which specifically assesses the integrity of the scapholunate ligament.
X-rays
Standard wrist X-rays may demonstrate several characteristic findings including:
- Widening of the scapholunate interval, known as the Terry Thomas sign
- An increased scapholunate angle
- The ring sign, where the scaphoid appears shortened and rounded
MRI scan
MRI scanning can assess injuries to the ligament. In some cases an MRI arthrogram is performed, where contrast dye is injected into the wrist joint before scanning to improve the accuracy of the examination.
Wrist arthroscopy
Wrist arthroscopy is a minimally invasive keyhole procedure that allows the ligament to be examined directly. It is often considered the most accurate way of assessing the extent of injury.
Find out what to expect at your outpatient appointment.
Treatment for scapholunate ligament injuries
Treatment depends on whether the ligament has been partially or completely torn and how long ago the injury occurred.
Partial tear
Some injuries represent a sprain rather than a complete rupture of the ligament.
These injuries usually require no specific surgical treatment. Initial management consists of:
- Rest
- A wrist splint
- Pain relief medication
- Gradual return to activity
Although a full recovery is expected, symptoms can continue to improve for up to 18 months after the injury.
Complete tear
In acute injuries the ligament can often be repaired surgically.
The operation is usually performed as a day case using either regional or general anaesthesia. Small smooth wires (K-wires) are inserted to hold the scaphoid and lunate bones together while the ligament heals.
A wrist cast is normally worn for approximately eight weeks. The wires are then removed before wrist mobilisation begins.
Ligament reconstruction
The ligament is ideally repaired within six to eight weeks of injury.
After this time, direct repair is often no longer possible and a ligament reconstruction may be required. This commonly uses one of the patient's own tendons, in a similar way to reconstruction of the cruciate ligaments of the knee.
Post-operative management is similar to that following ligament repair.
Long-term outcome
Even after successful treatment, many patients eventually develop some degree of wrist arthritis. Fortunately, the presence of arthritis on an X-ray does not necessarily mean symptoms will occur.
If arthritis does become symptomatic, treatment options remain available.
Longstanding scapholunate ligament injuries may lead to a pattern of arthritis known as Scapholunate Advanced Collapse (SLAC wrist).
Figure 4: Wrist arthritis following a longstanding scapholunate ligament injury (SLAC wrist).
Treatment of SLAC wrist is similar to that used for advanced scaphoid non-union and will depend on the severity of arthritis and the patient's symptoms.
Read more about post-operative care.
Persistent wrist pain after a fall?
If you continue to experience wrist pain, weakness or clicking following a wrist injury, Mr Robert Farnell can assess whether a scapholunate ligament injury may be responsible and advise on the most appropriate treatment.
Scapholunate Ligament Injury FAQs
What is the scapholunate ligament?
The scapholunate ligament is one of the main stabilising ligaments of the wrist, joining the scaphoid and lunate bones together.
How does a scapholunate ligament tear occur?
Most injuries occur after a fall onto an outstretched hand, although twisting injuries can also cause the ligament to tear.
What are the symptoms?
Common symptoms include wrist pain, swelling, clicking, weakness, loss of grip strength and reduced wrist movement.
What is the Terry Thomas sign?
The Terry Thomas sign describes widening of the gap between the scaphoid and lunate bones seen on an X-ray, indicating a scapholunate ligament tear.
Can MRI detect a scapholunate ligament tear?
Yes. MRI, particularly an MRI arthrogram, is useful for assessing injuries to the ligament.
What is wrist arthroscopy?
Wrist arthroscopy is a minimally invasive keyhole procedure that allows the surgeon to examine the ligament directly.
When is surgery recommended?
Surgery is usually recommended for complete ligament tears, particularly when diagnosed within the first six to eight weeks after injury.
What is a SLAC wrist?
SLAC stands for Scapholunate Advanced Collapse. It describes the pattern of wrist arthritis that may develop following a longstanding untreated scapholunate ligament injury.
Can arthritis develop after a ligament injury?
Yes. Arthritis is common after this injury, although not everyone with arthritic changes on X-rays develops symptoms.