Ulnar Impaction Syndrome in Vienna
The pain sits on the little-finger side of the wrist, exactly where the ulna ends. It comes on when turning the forearm, when leaning on the hand and when unscrewing a lid. Often the ulna projects too far relative to the radius — in everyday language, an ulna that is too long. I investigate this with an X-ray in the standard position.
In short
In ulnar impaction syndrome, the ulna projects too far relative to the radius (ulna plus variant). Under load and when the forearm is turned, its head strikes the carpal bones, above all the lunate and the triquetrum; between them lies the triangular disc (TFCC), which is worn down in the process. Typical is pain on the little-finger side that increases with rotation and pressure. The projection can be measured on an X-ray in the standard position; I assess the disc and cartilage with MRI. Treatment starts with offloading; if the pain persists, shortening the ulna can relieve the pressure.
What is ulnar impaction syndrome?
The forearm consists of two bones: the radius and the ulna. At the wrist both end side by side, with the carpal bones resting on them. How the load is distributed depends on how far the ulna projects in relation to the radius.
If it is level with the radius or slightly shorter, the radius carries most of the load. If it projects further — the ulna plus variant — a greater share of the load shifts onto the ulna. Its head then strikes the lunate and the triquetrum under load and during rotation. This repeated impact is called impaction.
The projection is often congenital, and in many people it never causes symptoms throughout their lives. It can also be acquired: if a distal radius fracture heals shortened or tilted, the ulna afterwards projects too far in relation to the radius. Symptoms arise when load is added — forceful gripping, weight-bearing with the wrist extended, twisting under load, weight-bearing exercises in strength training or gymnastics.
The triangular disc (TFCC) as a cushion
Between the head of the ulna and the carpal bones lies the triangular disc, the central part of the TFCC. It is a disc of cartilage with ligamentous parts; it distributes load and stabilises the connection between the ulna and the radius.
In ulnar impaction syndrome, this cushion lies in the path of the force. Constant pressure wears it down; a degenerative tear develops, and later cartilage damage on the lunate and the ulnar head as well. This is where the distinction matters: a TFCC tear after a fall or a sudden twist is an injury with a clear triggering event and is covered on the page about ligament injuries of the wrist. Ulnar impaction syndrome, by contrast, has a bony cause. If only the tear is treated and the projection is overlooked, the pressure remains.
Typical symptoms
- Pain on the little-finger side — where the ulna ends
- Pain when turning the forearm — keys, screw caps, door handles
- Pain when leaning on the hand — getting up from a chair, press-ups, support positions in training
- Tenderness over the head of the ulna — the spot is easy to point to
- Clicking or grinding — when turning under load
- Loss of grip strength — the grip becomes unreliable
How I make the diagnosis
First I ask about load, previous history and earlier fractures, and then examine specifically: the tender point over the ulnar head, pain when the ulna and the carpus are pressed together towards the little finger, and the stability of the ulnar head. The decisive step is the X-ray in the standard position — forearm in neutral rotation, elbow at a right angle, shoulder at the level of the wrist. Only in this position can the projection be measured comparably; images taken with the forearm in any other rotation suggest sometimes more, sometimes less length. An image taken with a clenched fist makes the impaction clearer. In the practice I use ultrasound for tendons and joint effusion; for the disc, the cartilage and bone marrow oedema in the lunate, I arrange an MRI.
Treatment: offloading first
Treatment begins with offloading. I discuss which movements cause the impaction and how they can be changed: supporting yourself on your fist instead of on the extended hand, making turning movements with the whole arm instead of the wrist, and adapting grips and training exercises. A support or a splint that limits rotation temporarily takes pressure off the little-finger side.
An ultrasound-guided injection can calm an accompanying irritation and at the same time helps me work out where the pain is coming from. For control and strength of the wrist, I work together with the physiotherapists in the same building at the Orthozentrum Döbling.
What offloading cannot do is change the relative lengths of the bones. If the pain persists, this is not a sign that you have not cooperated enough, but an indication of the bony cause.
My practice is a private practice, in Austria a Wahlarztordination. I do not settle directly with any public health insurer; you receive an invoice and submit it to your insurer — on request I take care of the submission for you. I explain how this works on the page about private practice and reimbursement.
When an operation is necessary
The aim of every procedure is to take the pressure off the little-finger side. The common approach is a shortening osteotomy of the ulna: I remove a narrow slice of bone from the shaft and fix the ends with a plate. The ulnar head moves back, the impaction stops, and at the same time the ligaments running to the radius are tightened slightly. The plate can be removed later, but does not have to be.
If the projection is small and the ligaments are stable, removing the joint surface of the ulnar head is also possible (wafer procedure) — either as an open procedure or arthroscopically, by looking into the joint with a camera. The shaft is left untouched. If the disc is torn, I treat it arthroscopically in the same session. I carry out necessary procedures at the ATOMOS Klinik Währing, the Privatklinik Döbling or the Rudolfinerhaus, and I accompany you from planning through the procedure to aftercare.
Which route is right depends on the extent of the projection, the condition of the disc and the cartilage — and on what your hand needs to do at work and in sport. Related conditions are a fracture of the radius at the wrist and wrist osteoarthritis; I explain other causes of symptoms on the little-finger side under assessing hand pain. An overview is given under hand surgery in Vienna.
Whether shortening is necessary is not decided by the X-ray alone. I make that choice together with you, once all the findings are available.
Frequently asked
Common questions about ulnar impaction syndrome
It refers to a difference in length at the wrist: the ulna projects too far relative to the radius, known technically as an ulna plus variant. The difference is small but changes the distribution of load considerably, because a greater share of the force passes through the ulna. Many people with this variant never have symptoms in their lifetime.
Typical is pain on the little-finger side of the wrist, where the ulna ends. It occurs when turning the forearm, when leaning on the hand and when gripping firmly; some people also feel grinding or clicking. The painful spot can usually be pinpointed exactly. Often there is no single injury that started it.
A TFCC tear is an injury to the cartilage and ligament complex, usually after a fall or a sudden twist. Ulnar impaction syndrome has a bony cause: under load, the projecting ulna strikes the carpus and wears down the disc over time. Both can exist side by side. If only the tear is treated and the projection is overlooked, the pressure remains.
The basis is an X-ray of the wrist in the standard position: forearm in neutral rotation, elbow at a right angle, shoulder at the level of the wrist. Only then can the projection of the ulna be measured reliably. For the disc, the cartilage and possible bone marrow oedema in the lunate, I also arrange an MRI. I use ultrasound in the practice.
First, offloading: avoid bearing weight with the wrist extended, make turning movements with the whole arm, and adapt grips and training exercises. A support or splint that limits rotation temporarily takes pressure off the little-finger side; an ultrasound-guided injection can calm an accompanying irritation. None of this changes the relative lengths of the bones.
In a shortening osteotomy, I remove a narrow slice of bone from the shaft of the ulna and join the ends with a plate. This moves the ulnar head back, and the impaction against the carpus stops. If the projection is small, removing the joint surface of the ulnar head is possible instead. Which route is right depends on the findings.
Yes. If a fracture of the radius at the wrist heals shortened or tilted, the ulna afterwards projects too far relative to the radius, even though the ulna itself is unchanged. Symptoms on the little-finger side that persist after the fracture has healed are therefore a reason to measure the relative lengths.
Dr. med. Martin Eigenschink
Specialist in Orthopaedics and Traumatology · Specialist in elbow, shoulder and hand surgery
Surgical and conservative treatment of the elbow, shoulder and hand, preferably minimally invasive. Practice at the Orthozentrum Döbling, 1190 Vienna. More about my background
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