Carpal & Scapholunate Instability

I have torn a ligament in my wrist

If you are suffering from a painful and swollen wrist after a fall on the outstretched hand, you might have torn a ligament in your wrist.

What is carpal and scapholunate instability?

The wrist is a construct made of 15 bones, radius and ulna, 8 carpal bones and 5 metacarpal bones. The carpal bones are organised in two rows and there are strong connections between theses bones reinforced by ligaments. When the wrist is forcefully hyperextended beyond breaking point, one of three things can happen: the radius brakes, the scaphoid (one of the carpal bones) breaks or the ligaments between scaphoid and lunate (another carpal bone) breaks. Torn ligaments between carpal bones cause instability and abnormal motion amongst them.

Who gets carpal and scapholunate instability?

Carpal and scapholunate instability occur when the ligamentous connection between carpal bones tear. This is in most cases following a traumatic event that forces the wrist in hyperextension like a fall on the outstretched hand. Some degenerative conditions however can also lead to attenuation of ligaments and subsequent instability.

Symptoms of carpal and scapholunate instability

Often there is swelling at the back of the hand and painful restriction of motion. There will be spot tenderness at the site of the ligament tear. In established carpal instability chronic pain and loss of grip strength are key features.

How is carpal and scapholunate instability diagnosed?

The history of a traumatic event where the wrist has been forced backwards is the first clue. Local spot tenderness, loss of range of motion and grip strength can be clinically evaluated and there are provocative manoeuvres that can elicit a click which indicates instability. X-ray and MRI are the best imaging studies. The instability between scaphoid and lunate causes those bones to loose their anatomical position. Where the scaphoid slips into flexion, the lunate gets extended. This phenomenon is called ‘DISI’ - dorsal intercalated segment instability.

Treatment for carpal and scapholu nate instability

Acute carpal ligamentous tears should be surgically repaired if diagnosed early. In these cases the torn ligaments can be repaired and the carpal bones are temporarily stabilised with wires. Often the diagnosis is made late and if symptoms persist ligament reconstruction is required.

Surgery for carpal and scapholunate instability

There are many procedures available to address carpal ligamentous instability. They all require a surgical approach at the back of the wrist and it depends on surgeons preference if local tendons are used as graft source or other grafts made available. In some cases temporary carpal bone stabilisation with wires is required to allow for the reconstruction to heal. The wires are usually removed at the 6 to eight week mark following the index procedure.

Preparing for carpal and scapholunate instability

Often an external brace for wrist immobilisation is necessary following the procedure. We will arrange fitting of a custom brace prior to the date of surgery. If required we will arrange for a bulk billed pre-admission clinic at the hospital. This is run by a specialist anaesthetist who will gather information and request investigations that are required for safe anaesthesia. Our reception staff will advise of costs, hospital and admission details.

Recovery from surgery for carpal and scapholunate instability

This surgery is in most cases performed as an over night stay in the hospital and follow up is closely manage by hand therapist for wound care and oedema management. Exercises are limited for the first six to eight weeks and recovery of range of motion will take several months to improve.