A lunate dislocation is a rare but are very serious wrist injuries. Left untreated, they lead to long-term wrist instability and disability. Read on to learn about this condition. Let’s start with anatomy.
The wrist
The wrist is made up of 3 joints. These include the distal radioulnar joint, radiocarpal joint, and the midcarpal joint. The distal radioulnar joint is made up of the ends of the forearm bones, the radius and ulna, at the wrist. This joint is essential for supination and pronation. Pronation is rotating the forearm, so the palm faces downward, and supination is forearm rotation where the palm faces upward.
The radiocarpal joint is made up of the radius and the first row of carpals. Carpals are the small wrist bones in between the forearm bones and the hand bones. The first row of carpals is called the proximal row and includes the scaphoid, lunate, and triquetrum. This row is more mobile than the distal row. The radiocarpal joint is the dominant joint for wrist extension. It assists in wrist flexion, radial deviation, and ulnar deviation.
Wrist extension is when the back of the hand moves toward the back of the forearm. Wrist flexion is when the palm of the hand moves toward the forearm. Radial deviation is when the hand moves to the thumb side. Ulnar deviation is when the hand moves towards the little finger side.
The midcarpal joint is the joint made up of the first and second row of carpals. The second row of carpals is also called the distal row and includes the trapezium, trapezoid, capitate, and the hamate. This row is more stable than the proximal row of carpals. The midcarpal joint assists in wrist extension and ulnar deviation. It is the dominant joint for wrist flexion and radial deviation.
What is a lunate dislocation?
A lunate dislocation occurs when the lunate bone dislocates toward the palm side of the wrist. Dislocation means that the lunate bone is no longer in the correct position. The dislocated lunate is no longer in alignment with the radius and capitate. This is a very rare but serious injury.
Lunate dislocations are the result of a very unstable wrist. This instability is a result of a ligament injury and/or fracture (break) of one of the carpal bones. A lunate dislocation is also considered the final phase in a four-phase progression of carpal instability.
The initial injury is thought to progress through phases known as the Mayfield progression.
- Stage 1 – Scapholunate dissociation
- This is a widening gap between the scaphoid and lunate bones.
- It is caused by an injury to the ligament that connects the scaphoid and lunate bones.
- Causes pain with clenched fist.
- Stage 2 – Perilunate dislocation
- This is the stage when the carpals surrounding the lunate dislocate.
- It is caused by a disruption of the ligament that connects the lunate and capitate bones.
- 60% of stage 2 injures are associated with a scaphoid fracture.
- Stage 3 – Midcarpal dislocation
- This is when the capitate dislocates from the lunate and the lunate subluxes from the radius. A subluxation is a partial dislocation. The lunate is still in contact with the radius but not in correct alignment.
- This is caused by a disruption of the ligament that connects the lunate and triquetrum.
- It could also be caused by a triquetrum fracture.
- Stage 4 – Lunate dislocation
- In the final stage, the lunate will dislocate toward the palm of the hand.
- This is caused by a disruption of the ligament that connects the radius and the lunate.
Lunate dislocations usually occur after a high energy injury such as a sports injury, motor vehicle accident, fall, or industrial accident. These injuries are frequently missed. Lunate dislocations are misdiagnosed in about 25% of clinical exams and x-rays. Therefore, the true prevalence of the condition is unknown.
What are the symptoms of a lunate dislocation?
There are several symptoms associated with lunate dislocation. These include:
- Wrist pain
- Decreased wrist mobility
- Swelling at the wrist
- Wrist deformity
- Numbness and tingling in the palm of the hand
- Hand weakness
Will l need surgery?
The answer is probably. Those treated without surgery tend to have poor outcomes and maintain significant wrist instability. The type of surgical repair will depend on the severity and age of the injury.
What are the complications of lunate dislocation?
There are several complications associated with this condition. These include:
- Post -traumatic arthritis – This refers to osteoarthritis that tends to occur over time to joints that have suffered traumantic injuries. Arthritis can cause deformity, disability, stiffness, pain, and swelling at the wrist.
- Median nerve neuropathy – If the lunate dislocates toward the palm, it can go into the carpal tunnel. This would compress the median nerve and cause numbness, tingling, and weakness in the palm.
- Transient lunate ischemia – This is when there is inadequate blood supply to the lunate. It is a self-limiting condition and will go away over time.
- Osteonecrosis – This is the death of a bone due to lack of blood supply.
- Complex regional pain syndrome – This is a complex pain disorder that can affect an area of injury. It is characterized by pain that is greater than would be expected from the injury.
Who should I see?
- Orthopedic hand specialist – If you have had a previous high energy wrist injury (whether recent or in the past) and you suspect that you have wrist instability, then it is best to see an orthopedic hand specialist. Because of the potential complications, this injury should be treated quickly. The orthopedist can order imaging and inspect the wrist to determine the extent of the injury and advise on the best course of treatment.
- Physical therapist – Physical therapy will be needed to regain mobility and strength in the wrist after surgery. Because of the extended time in a cast or splint, the wrist will be stiff and sore when trying to move or use it. Your PT can evaluate you to determine the extent of your mobility and strength deficits and use manual therapy, as well as, stretching and strengthening to help address all problems in and around the wrist.
What can I do?
- Relative rest – Resting the area to decrease further pain and damage from occurring is one of the best ways to allow the wrist to heal. If you are not able to participate in your activity or sport, then you can supplement with non-irritating activities such as walking or jogging while your wrist is healing.
- Ice – Ice can help decrease pain and symptoms at the wrist. Ice the painful area for 15 to 20 minutes at a time. I would recommend using an ice pack several times per day if the pain is constant or is preventing you from participating in an activity. Ice immediately after activity.
- The following are activities that you can do after the cast or splint is removed and you are cleared by your surgeon.
- Wrist flexion and extension stretching – You will need to stretch out the wrist flexors and extensors. This will feel very tight and sore at first. Begin with a gentle stretch. You can stretch more aggressively as the soreness subsides. See the video below.
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- Wrist strengthening – It is important to strengthen the wrist after a long period of immobilization. Begin with low to no resistance and slowly increase as it becomes easier. You should have minimal pain when performing the exercise and no pain afterwards. Below is a video showing how to strengthen the wrist using resistance bands.
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- Grip strengthening – Strengthening the muscles for gripping is important since a wrist instability can affect this action. Performing gripping exercises is helpful for recovering hand strength. See the video below.
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- Strengthening the muscles around the elbow and shoulder – Strengthening the muscles around the elbow and shoulder are also important in being able to return to your activity. Decrease your resistance or number of repetitions if you are having pain in the wrists. Using loop resistance bands, dumbbells, or resistance bands can increase strength and difficulty. See the videos below.
In review
- The wrist is made up of 3 joints.
- These include the distal radioulnar joint, radiocarpal joint, and the mid carpal joint.
- Carpals are the small wrist bones in between the forearm bones and the hand bones.
- A lunate dislocation occurs when the lunate dislocates towards the palm side of the wrist.
- Lunate dislocations are the result of a very unstable wrist.
- The initial injury will progress through phases known as the Mayfield progression.
- Lunate dislocations usually occur after a high energy injury.
- Symptoms include wrist pain, swelling, and deformity.
- This is a frequently missed diagnosis which could lead to long-term disability and pain.
- There are several complications that could occur including arthritis and median nerve neuropathy.
- Surgery will probably be needed.
- There are things that you can do.
- Rest
- Ice
- After surgery or cast is removed
- Wrist flexion and extension stretching
- Wrist strengthening
- Grip strengthening
- Elbow and shoulder strengthening
As always, If you have questions about the content of this post or any other musculoskeletal questions, please e-mail me.
Additional resources
https://www.orthobullets.com/hand/6045/lunate-dislocation-perilunate-dissociation
https://coreem.net/core/lunate-dislocation/