The lunate bone is one of 8 critical bones in the wrist that, due to its unique shape and position, help to stabilise the wrist and support movement.
However, due to the lunate position, it is also one of the most common bones to see trauma and impact affect it, hence causing pain and stiffness in the wrist. Often resulting in the lunate bone condition known as Kienböck’s disease.
In this post, we look at lunate instability in more detail, as well as Kienböck’s wrist and how our wrist specialists can help you.
Lunate bone
The human wrist consists of 8 critical bones (known as carpal bones), which are divided into two rows, composed of four bones in each, allowing for a range of movement in the wrist.
All bones are then connected through a series of ligaments.
The specific lunate is located in the proximal row, alongside the scaphoid, pisiform, and triquetrum, and is unique for its small, crescent-shaped structure.
Acting as a bridge between the two rows of carpal bones, ensuring smooth motion, specifically, the lunate sits lateral to the scaphoid bone and medial to the triquetrum, and when we delve into more detail, you will find the lunate inferior to the capitate and hamate.
Connected to two other bones that make up the forearm, the radius and ulna, the lunate bone helps to provide movement and stability to the wrist.
Lunate instability
Lunate instability is one of the most common instabilities you will find in the wrist. It can occur at any age; however, adults aged 20 to 40 are more susceptible.
It is most often caused by trauma to the wrist from falling onto an outstretched hand and extended wrist. When this occurs, trauma to the ligament’s valor radio scapholunate, scapholunate interosseous, or dorsal scapholunate occurs.
However, lunate instability can also be caused by other conditions, such as:
- Gout
- Irregular/different length forearm bones
- Sickle cell
- Lupus
- Repetitive wrist stress
- Irregular lunate shape.
Kienböck’s wrist
When such conditions or trauma affect the lunate, blood flow to it can be disrupted, leading to what is termed Kienböck’s wrist.
Well known as avascular necrosis of the lunate bone, Kienböck’s disease can lead to arthritis, as when blood flow is disrupted to the lunate bone, this lack of blood flow will lead to the bone slowly dying unless treatment is sought.
Some of the symptoms you may experience can include:
- Pain, increasing over time if receiving no treatment
- A creaking or crackling sound when you move your wrist
- A feeling of instability in the wrist when carrying out certain activities
- The wrist may be tender to the touch
- Swelling
- Stiffness
- Weakness
- You don’t have a full range of motion.
Kienböck treatment
If you suspect Kienböck’s disease or are experiencing wrist pain, it’s important to speak to a specialist as soon as possible.
Treatment will include taking a complete medical history as well as understanding the symptoms you are currently experiencing.
A physical examination will be carried out, followed by a diagnostic exam, where measurements can be taken to examine the space between the lunate and the scaphoid.
If there is an identified space larger than 2mm, then this may indicate lunate instability, and further diagnostics may be carried out.
Such as an MRI or CT scan to check blood flow, ligament damage, and bone structure.
Treatment options available
The good news is that there is a range of treatment options available for lunate instability, and the treatment option type will depend on the individual, stage, and symptoms experienced.
The most immediate treatment is to rest and immobilise the wrist using a splint, to reduce movement and manage pain.
Over-the-counter pain relief can also help to reduce swelling and minimise discomfort.
Physiotherapy can help by providing the right range of exercises to build and strengthen the wrist ligaments and help the wrist regain full movement.
Corticosteroid injections to help with pain and reduce inflammation. However, these are not a long-term solution.
If lunate instability is severe and there is significant ligament damage, surgery may be the best course of action. Surgery can range from ligament repairs to carpal bone fusion. For example, surgery can include:
- Revasculisation
- Joint levelling
- Partial or total joint fusion
- Core radial compression procedures.
The experts at Ladan Hajipour
Treatment of lunate instability will depend on the severity and stage of the disease; however, at Ladan Hajipour, our aim is always to relieve wrist and hand pain and to help restore full function.
Advising you on the best course of treatment as well as tailoring treatment plans to you, the individual, our team is an expert in their field, understanding the importance of getting your full range of motion back to allow you to continue with your everyday activities.
If you are experiencing any symptoms in your hand or wrist, please book a consultation with one of our hand and wrist specialists today.
Read the next article: How is Kienböck’s disease diagnosed?