Positive ulnar variance

What is positive ulnar variance? 

The forearm is made up of two bones: the ulna and the radius. The ulna, which is located on the inner side of the arm, may sometimes show a condition called positive ulnar variance. This means the ulna bone is longer than its neighboring bone, the radius, which is on the outer side of the arm. Normally, these two bones are similar in length, or the ulna may be slightly shorter.

In such cases, it is also referred to as ulnar impaction syndrome because the ulna is exposed to an increased impact on the carpal bones.

The ulnar and radius are connected to each other by a thin membrane and rotate against each other when the wrist turns. The two bones are significantly involved in the elbow joint and play an important role in the function of the wrist.

The wrist can be divided into two partial joints. The proximal part of the wrist is formed by some of the carpal bones and the radius. The ulna is also indirectly involved and connected to the carpal bones via a cartilaginous disc called the discus. An excess length of the ulna therefore is significant for the functioning of the wrist.

Causes of a positive ulnar variance

The positive ulnar variance can arise because of a wrist injury, or it may be congenital.

One of the most common fractures in Germany is a distal radius fracture in the wrist which usually occurs after a fall on the outstretched wrist. Once the radius fracture has healed, in many cases it is slightly shortened, making the ulna longer in comparison.

An ulnar impaction syndrome can also occur because of an ulnar fracture. If the ulnar bone is broken while the patient is still growing, then the body's repair mechanisms can overshoot during the healing causing it to protrude past the radius.

In the case of a congenital positive ulnar variance, the symptoms usually occur in both wrists. Here, both forearm bones grow unequally, and the ulna is relatively too long.

Symptoms of positive ulnar variance: how does it manifest itself?

Symptoms of positive ulnar variance occur in the wrist area and vary in severity depending on the extent of the ulnar overlength. 

Generally, those affected report pain on the ulnar side of the wrist, i.e. on the side of the little finger. Initially, the pain is only felt during exertion and later becomes permanent.

If the condition persists over a longer period, the disc between the ulna and the carpal bones can tear. Affected individuals often notice pain along with a snapping or blocking sensation during the rotational movement of the wrist.

In cases which are milder, with an overlength of about 1-2 millimeters, the positive ulnar variance may not cause any symptoms at all. The diagnosis is therefore often made incidentally, when an X-ray of the wrist is taken following a fall, for example.

How does a specialist diagnose positive ulnar variance?

A hand surgeon should be contacted if the patient has had wrist pain for a long time. The first step is to take a detailed medical history, through which the experienced specialist can gather initial clues to suspect ulnar impaction syndrome. Information about previous injuries is particularly important here.

The thorough examination of the wrist can provide additional clues for the diagnosis. When pressure is applied to the wrist's ulnar end or the cartilage disc located there, patients usually report significant tenderness. To confirm the suspected diagnosis, the specialist will then order further tests.

Different imaging methods can provide information about the variation of the ulna. Generally, a standard X-ray is taken first to determine the excess length. Often, this X-ray is taken under load so that the length of the bones can be evaluated more accurately. During the examination, patients clench their fist or grip a small ball. 

As the positive ulnar variance can exert pressure on the disc and on the cartilage of the adjacent carpal bone, further tests should be carried out to check the condition of the cartilage. This could be done by means of an MRI scan, CT scan or wrist arthroscopy. In a wrist arthroscopy, a camera is inserted into the joint as part of a surgical procedure so that possible damage can be diagnosed or treated as needed. 

If there is suspicion of a congenital positive ulnar variance, an X-ray of both wrists should be taken, even if the symptoms initially only occur on one side. Early diagnosis and treatment can prevent possible consequential damage. 

Positive ulnar variance therapy: how is it treated and what options are available?

Overlength of the ulna should always be treated. The type of treatment that is indicated in each case depends on the severity of the condition. In any case, therapy aims to relieve pressure on the ulna bone and the involved cartilage of the wrist. 

• Conservative therapy

Conservative therapy is only considered in exceptional cases of ulnar impaction syndrome, as it can only alleviate the symptoms and not cure the cause of the pain. 

In the case of acute pain, the wrist can be immobilized for some time in a brace or an orthosis. Taking anti-inflammatory painkillers can also bring relief to those affected. 

Unfortunately, however, these measures only have long-term success in a limited number of cases, which is why surgical measures will have to be considered.  

• Surgical therapy

There are various surgical methods used to treat positive ulnar variance. Most of these techniques are highly complex, and their success depends greatly on the experience of the specific hand surgeon with the method used.

Two main procedures are used. 

The less invasive method involves the removal of part of the ulna in the wrist area, usually part of the cartilage is also removed here. This allows to reduce the pressure on the ulna and the carpal bones. One potential complication of this procedure is injury to ligament structures in the wrist region. 

A more invasive method is the ulnar shortening osteotomy. A thin slice of bone is removed from the middle portion of the ulna. The bone is then secured with screws and a small plate so that the now shortened ulna can heal. The material can either remain in the bone or be taken out again after the healing process. 

Which surgical method is appropriate depends on the surgeon and their experience. The benefits and risks of the operation must be carefully considered in each case. 

Positive ulnar variance treatment in physiotherapy

Physiotherapy cannot cure ulnar impaction syndrome. However, it can be effective as part of conservative therapy and, more importantly, as a part of post-operative rehabilitation. 

In all cases, wrist-stabilizing techniques are primarily used. Since the healing process after surgical treatment of positive ulnar variance can take several months, supportive physical therapy is beneficial. Patients are shown various techniques to gradually increase the load on the wrist.

It is important to remember that physiotherapy should always be adapted to the respective surgical technique and to the individual patient's circumstances. 

Which doctors and clinics specialize in positive ulnar variance?

Wrist complaints should always be evaluated by an experienced hand surgeon and ulnar impaction syndrome requires a high level of expertise from the surgeon. 

We want to help you find a hand surgeon who has extensive experience in the treatment of positive ulnar variance to provide you with the best possible care. 

We have therefore thoroughly reviewed all experts listed here and found them to be extremely competent. So, arrange an initial appointment with one of our specialists quickly and easily.