The ulna is the bone on the pinky side of your forearm. It interacts with the radius (bone on the thumb side) and with the carpal bones (small bones in your wrist). Because the radius ends with an angle, you could say the ulna is shorter than the radius. This leaves a bit of space between the ulna and the carpal bones. This can often lead to instability on the ulnar side which is why ulnar-sided wrist pain is so common.
So what goes wrong? There a number of common issues on this side of the wrist that we will go over in this week’s blog:
We previously did a blog about TFCC injuries. The TFCC is the complex of ligaments that stabilizes the ulna to the radius and carpal bones on that side of the wrist. It can be injured with overuse/repetitive motion over time or an acute injury such as a fall.
If you experience wrist pain due to this, your therapist can do some tests with to determine if your TFCC is what’s causing your pain. Typically patients with TFCC injury have difficulty bearing weight onto their wrists.
Ulnar Nerve Impingement at Guyon’s Canal, Tingling & Wrist Pain
The ulnar nerve (often indicated in cubital tunnel syndrome, travels along the ulnar side of your wrist and through Guyon’s canal. The ulnar nerve travels under one of the wrist bones, the hamate. This bone has a hook structure on it which makes up Guyon’s canal. An injury to the hook of the hamate can cause increased pressure on the nerve which leads to nerve symptoms.
These nerve symptoms could be numbness, tingling, pins & needles, or it may be as mild as a “weird feeling” in your pinky and ring finger. In later stages of nerve irritation or injury, you may experience “clawing” of your ring and pinky finger–this is when the tip joints start to rest in a more flexed position. If the nerve is left in an irritated or compressed state for a long period of time, you may then experience muscle wasting in some of the muscles in the hand. For more information regarding ulnar nerve impingement, check out this link.
ECU and FCU Tendinitis
The ECU, or extensor carpi ulnaris, is a muscle found on the dorsal or back of your forearm. It travels right along the ulna and its tendon often gets irritated at the ulnar styloid (bump that sticks up on pinky-side of your wrist). The ECU functions to lift your wrist back and also bends it sideways toward the pinky side (think about moving wrist sideways while reaching keys on keyboard). Any activity requiring this motion repetitively can cause tendinitis of the ECU.
The FCU (flexor carpi ulnaris) is a muscle on the palm-side of your forearm.
Here’s more information on the first step of treating arthritis.
Typically, the ulna is shorter than the radius at the wrist. Ulnar impaction occurs when for some reason, the ulna becomes the same length or longer than the radius. The measurement is called ulnar variance. Typically, the ulnar variance is negative, because it should be shorter than the radius.
In ulnar impaction, there will be a positive ulnar variance as it is now longer than the radius. Ulnar impaction is the wear and tear that occurs on the wrists bones from the ulna being too long. This can occur from injury such as a radius fracture, or some people are born with a positive ulnar variance. Your doctor may recommend 4-6 weeks of hand therapy with bracing to see if the pain calms down. If this does not work, the next steps could be cortisone injections or surgery to shorten the ulna.
For more information, check out a case study here.
Having ulnar-sided wrist pain? Interested in trying therapy before seeing a hand surgeon? Call LB Hand Therapy today to see if you are eligible to come to therapy before seeing a doctor! We’re here to help! Visit Where to begin to learn how to become a patient.
Julie Williford MOT, OTR/L, CPAM