Positive ulnar variance means the ulna, the forearm bone on the pinky side, extends slightly farther toward the wrist than the radius beside it. When that length difference becomes large enough, the ulna presses into the small bones of the wrist and the cartilage between them, causing pain, stiffness, and progressive damage to surrounding structures. The condition can develop from a childhood fracture, repetitive loading from sports, or simply from a person’s natural anatomy. Treatment ranges from splinting and activity changes to surgery that shortens the ulna back to its correct length.
What Ulnar Variance Actually Describes
If you hold your arm out with the palm facing down, two bones run side by side from your elbow to your wrist. The radius sits on the thumb side, the ulna on the pinky side. In a “neutral” wrist, the far ends of both bones line up almost evenly. Ulnar variance is the measurement of how much one bone overshoots or undershoots the other. When the ulna sits longer than the radius, the variance is called positive. When the ulna is shorter, it’s negative. Most people fall somewhere close to neutral, but the exact measurement varies from person to person and even between your two hands.
A study of 600 wrists found that women tend to have slightly more positive ulnar variance than men. The median measurement in women was about 0.85 mm on the positive side, compared with 0.4 mm in men, and the difference held regardless of age or which hand was measured. Individual measurements ranged widely, from roughly negative 5 mm to positive 5.7 mm, which means perfectly healthy people can sit at very different spots on this spectrum. The trouble starts when the ulna overshoots far enough to grind against the wrist bones during everyday use.
How Positive Ulnar Variance Develops
Some people are simply born with a slightly longer ulna, and their variance becomes more positive as they age. But the most clinically relevant cases tend to have a clear cause behind them.
The most common cause in younger patients is a fracture of the distal radius, the end of the radius near the wrist. If the fracture heals short or heals crooked, the radius effectively becomes shorter than the ulna, creating a positive variance that wasn’t there before. Malunion of a distal radius fracture often leads to disturbed ulnar variance, and frequently comes paired with damage to the triangular fibrocartilage complex (TFCC), the cushion of cartilage between the ulna and the wrist bones.1PubMed Central. Ulnar Shortening Osteotomy After Distal Radius Fracture Malunion: Review of Literature
In children and adolescents, the concern shifts to the growth plate. The distal radius has a growth plate near the wrist that is responsible for much of the forearm’s lengthening during development. If a fracture or repeated stress damages that growth plate, the radius can stop growing while the ulna keeps going. Growth plate arrest after a distal radius fracture occurs in roughly 5% of pediatric patients, and the resulting ulnar variance can produce significant pain and functional limitations.2PubMed Central. Physeal Growth Arrest in Distal Radius Fracture: A Case Report When the arrest is partial or complete, the consequences extend beyond just the length mismatch. The joint between the two forearm bones at the wrist can become unstable, and the TFCC can be injured as the ulna pushes past its normal position.3PubMed Central. Addressing Bilateral Post-traumatic Distal Radius Growth Arrest with Positive Ulnar Variance with Acute Ulnar Shortening Osteotomy and Distal Radioulnar Joint Fixation in a 13-Year-Old Child: A Case Report
Why Athletes Are Especially Vulnerable
Sports that load the wrist heavily and repeatedly can push ulnar variance in the positive direction even without a single dramatic injury. Gymnasts are the best-studied example. A study of nonelite gymnasts found radiographic signs of stress injury to the distal radial growth plate in a quarter of participants. Ulnar variance in the gymnasts was more positive than age-matched norms, with an average side-to-side difference of about 0.9 mm, suggesting that the loading was either slowing the radius’s growth, accelerating the ulna’s, or both.4PubMed. Distal radial growth plate injury and positive ulnar variance in nonelite gymnasts
A broader scoping review of athletes across multiple sports confirmed that athletes display more positive ulnar variance than nonathletes, and that variance tends to become more positive over time in longitudinal follow-up. The review also found that TFCC tears, focal lunate necrosis, and ulnar abutment were all associated with positive variance in athletes.5PubMed Central. Ulnar Variance in Athletes: A Scoping Review Any sport involving repeated wrist loading, gripping, or forearm rotation can contribute, including racquet sports, rowing, and baseball.
What Happens Inside the Wrist
When the ulna sits too long, it bumps into the lunate and triquetrum, two small carpal bones on the pinky side of the wrist. Between them sits the TFCC, a disc of cartilage and ligaments that acts as both a cushion and a stabilizer for the joint. Positive ulnar variance compresses the TFCC and the nearby cartilage surfaces every time you grip, twist, or bear weight through your hand.
The numbers from cadaver and clinical studies are striking. In one study examining wrists with positive ulnar variance, TFCC tears were found in about 91% of cases, compared with 63% in neutral-variance wrists and 40% in controls. Central disc perforations, the classic wear-through injury, were four times more common in positive-variance wrists than in neutral ones. Degenerative changes in the joint between the ulna and the lunate or triquetrum appeared in 42% of the positive-variance group, versus just 5% in neutral-variance wrists.6PubMed Central. Does ulnar variance relate with TFCC lesions?
This progressive grinding has a name: ulnar impaction syndrome, also sometimes called ulnar abutment. It is a degenerative condition in which the mechanical overload from the long ulna gradually wears down the disc, softens the cartilage on the lunate and triquetrum, and can eventually lead to bone necrosis and joint instability. The symptoms tend to worsen with activity and do not reliably improve with rest alone.7PubMed. Arthroscopic treatment of ulnar impaction syndrome
Symptoms and What They Feel Like
The hallmark complaint is pain on the pinky side of the wrist that flares with gripping, twisting a doorknob, pushing off a surface, or rotating the forearm. Some people notice swelling after activity. Others describe a clicking or snapping sensation during wrist movement. In sports, these symptoms tend to appear during activities that involve repeated forearm rotation, wrist bending side to side, axial loading through the palm, or gripping equipment tightly.8Current Sports Medicine Reports. Ulnar-Sided Wrist Pain in the Athlete: Sport-Specific Demands, Clinical Presentation, and Management Options
The challenge is that ulnar-sided wrist pain has a long list of potential causes. Ligament tears, tendon problems, nerve compression, and arthritis can all produce pain in a similar location. A methodical physical exam with provocative tests that stress specific structures is essential for narrowing the diagnosis.9PubMed. Evaluation of Ulnar-sided Wrist Pain In a typical exam, your doctor will press over the TFCC, rotate your forearm, and load the wrist in different positions to see which maneuvers recreate your pain.
How It Shows Up on Imaging
A standard X-ray of the wrist, taken with the forearm in neutral rotation, is the starting point. The measurement of ulnar variance is straightforward on this view: the doctor compares the positions of the far ends of the radius and ulna. But a neutral-rotation film captures the wrist at rest, and some people’s variance changes significantly under load. A pronated grip X-ray, where you squeeze a handle as hard as you can while the image is taken, can reveal increases in ulnar variance that a resting film misses entirely. One study of patients with ulnar wrist pain found that the pronated grip view produced significantly more positive variance readings than the neutral view, and the authors argued that both views should be obtained before planning treatment so that dynamic changes aren’t overlooked.10PubMed. The importance of the pronated grip x-ray view in evaluating ulnar variance
If surgery is being considered, or if the doctor suspects soft-tissue damage to the TFCC or cartilage, MRI usually follows. High-resolution MRI is useful for evaluating the relationship between ulnar variance and the soft-tissue structures on the ulnar side of the wrist.11PubMed. Study of ulnar variance with high-resolution MRI: correlation with triangular fibrocartilage complex and cartilage of ulnar side of wrist MRI can reveal TFCC tears, cartilage softening on the lunate, bone marrow edema from chronic impaction, and early joint degeneration, all of which help guide the treatment decision. Some centers use 3T MRI, which provides higher resolution and can pick up subtle damage that lower-strength magnets miss.12PeerJ. The relationship of ulnar variance with pathologies detected by magnetic resonance imaging in patients with chronic or subacute wrist pain
Measurement technique matters too. Multiple methods exist for measuring ulnar variance on X-ray, with no universal standard. A scoping review of studies on ulnar variance in athletes found that researchers used at least three different measurement techniques, and only about half specified taking a standard posteroanterior view.5PubMed Central. Ulnar Variance in Athletes: A Scoping Review Lateral radiographs may also provide useful information, since traditional methods using only the front-to-back view have known shortcomings.13PubMed. Measurement of ulnar variance from the lateral radiograph: a comparison of techniques The practical takeaway is that if you are comparing measurements taken at different clinics or different time points, the technique used matters just as much as the number itself.
Non-Surgical Treatment
When positive ulnar variance is causing symptoms but the damage hasn’t progressed to advanced cartilage loss or joint instability, conservative treatment is a reasonable first step. The standard approach includes activity modification to avoid the loading patterns that provoke pain, anti-inflammatory medication, and sometimes a corticosteroid injection into the wrist.
Splinting can also help. A study of patients with ulnocarpal abutment syndrome found that a custom-made wrist splint significantly reduced both pain scores and functional disability scores. Seven of ten patients in the study continued wearing the splint long-term, and three of those seven achieved complete pain relief.14PubMed. Conservative treatment using a newly designed custom-made wrist splint for ulnocarpal abutment syndrome That said, conservative management works best for milder cases. If the TFCC is already torn through, or if cartilage and bone changes are visible on MRI, nonoperative treatment may control symptoms temporarily but is unlikely to reverse the underlying problem.
Surgical Options
When conservative treatment fails, surgery aims to eliminate the mechanical conflict between the ulna and the wrist. The two most common procedures are ulnar shortening osteotomy and the arthroscopic wafer procedure.
Ulnar Shortening Osteotomy
This is the workhorse operation for positive ulnar variance. The surgeon cuts across the ulna shaft, removes a thin wafer of bone (typically 2 to 3 mm), and fixes the bone back together with a plate and screws. The goal is to bring the ulna back to neutral or slightly negative variance. In a retrospective study of 47 patients treated with ulnar shortening osteotomy, the median follow-up was about three years. Functional outcome scores were quite good: the median PRWE score was 7 and the median Quick-DASH score was 4.5, both indicating low levels of residual pain and disability. Twenty-four of the 29 patients who returned for follow-up rated their subjective improvement as very high, and bone healing was achieved in all cases.15PubMed Central. Ulnar shortening osteotomy for ulna impaction syndrome with positive ulnar variance: retrospective outcome analysis
Grip strength also recovers meaningfully after the procedure. A cohort study of 106 patients found that mean grip strength improved from 24 kg before surgery to 30 kg at twelve months.16PubMed Central. Outcomes of ulna shortening osteotomy: a cohort analysis of 106 patients A separate prospective series showed that range of motion and grip strength began improving significantly between the eighth and twelfth postoperative weeks.17PubMed Central. Time-Dependent Recovery of Outcome Parameters in Ulnar Shortening for Positive Ulnar Variance: A Prospective Case Series
Arthroscopic Wafer Procedure
For patients with less than about 3 mm of positive ulnar variance and a concurrent central TFCC tear, the arthroscopic wafer procedure is an alternative. Rather than cutting the ulna shaft, the surgeon works through small incisions to shave down the distal tip of the ulna from the wrist side while also cleaning up the torn TFCC. The ulna is trimmed to neutral or slightly negative variance. Because there is no bone cut to heal and no plate needed, recovery tends to be faster and complication rates are lower.18PubMed Central. Arthroscopic wafer procedure for ulnar impaction syndrome
A meta-analysis comparing the two procedures across eight studies found that functional outcomes, pain scores, grip strength, and the amount of ulnar shortening achieved were similar between the two groups. Where the arthroscopic wafer procedure stood out was in safety: patients who had the arthroscopic approach had significantly fewer complications and a much lower reoperation rate than those who had the osteotomy.19PubMed Central. Arthroscopic wafer procedure versus ulnar shortening osteotomy for ulnar impaction syndrome: a systematic review and meta-analysis The limitation is that the wafer procedure is only suitable for milder degrees of positive variance. Patients with more than 3 mm of excess ulna length generally need the osteotomy.
Complications Worth Understanding
Ulnar shortening osteotomy is effective, but it is not a minor procedure, and anyone considering it should understand the trade-offs. The ulna is a relatively thin bone, and cutting across it and re-fixing it creates a healing challenge. A multicenter review noted that nonunion rates have been reported as high as 18% and hardware removal rates as high as 45%.20PubMed. Risk Factors for Complications in Ulnar Shortening Osteotomies: A Multicenter Retrospective Review In a study of 98 patients, about one in five needed hardware removal, roughly 6% developed a nonunion, and about one in three ultimately underwent some form of reoperation.21PubMed Central. Nonunion and Reoperation After Ulna Shortening Osteotomy
Hardware irritation is the single most common reason patients return to the operating room. The plate sits right under the skin on the back of the forearm, and many patients can feel it or find it bothersome. Nonunion, where the bone fails to heal across the osteotomy site, is the more serious complication. Plate design and size influence healing rates, and newer systems specifically designed for ulnar shortening have improved outcomes compared with generic small-fragment plates.22PubMed Central. Influence of Plate Size and Design upon Healing of Ulna-Shortening Osteotomies Other complications include chronic regional pain syndrome and pseudoarthrosis, both of which were seen in a small number of patients in the retrospective outcome study mentioned earlier.15PubMed Central. Ulnar shortening osteotomy for ulna impaction syndrome with positive ulnar variance: retrospective outcome analysis
These complication rates don’t mean the surgery is a bad option. Most patients end up with substantially less pain and better function. But if your variance is under 3 mm and you have a TFCC tear, the arthroscopic wafer procedure’s lower complication profile makes it worth discussing with your surgeon before defaulting to the osteotomy.
Pediatric Cases and Growth Plate Management
Managing positive ulnar variance in a child whose bones are still growing presents a different problem. The underlying issue is often that the radius growth plate has been damaged by a fracture and has partially or fully closed, so the radius stops lengthening while the ulna keeps growing. Simply shortening the ulna in a child who still has years of growth remaining would be a temporary fix at best, since the discrepancy would return as the ulna continues to grow.
One approach is ulnar epiphysiodesis, a procedure that intentionally stops the ulna’s growth plate from adding more length. If done at the right time, this prevents the variance from getting worse and avoids repeated surgeries. A study evaluating this technique found that it can effectively halt further positive variance development after a distal radius growth plate arrest.23PubMed. Radial Inclination and Volar Tilt Following Ulnar Epiphysiodesis for Distal Radius Physeal Arrest Timing is critical: if the epiphysiodesis is done too early, it may leave the child with a short ulna on the other side of neutral. If it’s done too late, the variance may already have caused damage. In some cases, when the variance is already substantial at the time of diagnosis, an acute ulnar shortening osteotomy is performed alongside the growth-plate procedure to correct the existing mismatch while preventing future worsening.3PubMed Central. Addressing Bilateral Post-traumatic Distal Radius Growth Arrest with Positive Ulnar Variance with Acute Ulnar Shortening Osteotomy and Distal Radioulnar Joint Fixation in a 13-Year-Old Child: A Case Report
When the Problem Is Dynamic
Some people have X-rays that look close to neutral at rest but develop clinically meaningful positive variance only when they grip hard or rotate the forearm. This “dynamic positive variance” is easy to miss. It happens because gripping causes the radius to shift slightly toward the elbow, effectively lengthening the ulna relative to the wrist without the ulna itself actually moving. The standard resting X-ray does not capture this shift, which is why the pronated grip view is so important for anyone with unexplained ulnar-sided wrist pain.10PubMed. The importance of the pronated grip x-ray view in evaluating ulnar variance
Wrist position compounds the effect. A pilot study examining the combined influence of forearm pronation, gripping, and wrist deviation on ulnocarpal relationships found that the distance between the ulna and the lunate changed with wrist position, and that a greater portion of the lunate became uncovered by the radius during certain movements.24PubMed Central. Pronated Grip View With Wrist Deviation: A Pilot Study on the Effect on Ulnocarpal Relationships This explains why some patients have severe symptoms during specific activities but feel fine at rest, and why their resting X-rays can look deceptively normal. If your symptoms are clearly activity-related but your initial films look unremarkable, asking for a pronated grip view could reveal what’s actually going on.
Living With Mild Positive Variance
Not everyone with a slightly long ulna needs treatment. As the measurement data on 600 wrists show, plenty of healthy people walk around with a millimeter or two of positive variance and never develop symptoms. The variance becomes a clinical problem when it combines with repetitive use, prior injury, or enough excess length to overload the TFCC and cartilage surfaces. If you’ve been told you have mild positive ulnar variance on an incidental X-ray but have no wrist pain, there is typically no reason to pursue treatment.
For those with early or intermittent symptoms, the practical steps are straightforward: limit the activities that aggravate the wrist, consider a wrist splint for high-load tasks, and strengthen the forearm muscles that help stabilize the joint. Athletes may need to modify training volume or technique rather than stop entirely. Surgery enters the conversation when conservative measures have been given a fair trial and the pain continues to interfere with daily life or sport. At that point, the imaging workup, including the pronated grip view and MRI, determines whether the arthroscopic wafer procedure can handle the job or whether a full osteotomy is needed.