The Natural History and Treatment of Arm Problems in HME

Mr Peter Burge FRCS
Consultant Orthopaedic Surgeon and Arm Specialist

The information in this page was taken from the Minutes of HME Support Group Meeting held on Saturday 8th May 1999 at the Nuffield Orthopaedic Centre, Oxford, UK. It was edited by Dr D. G. Small, BM, BCh, MRCP (UK) and has been checked by the Speaker.

Mr Peter Burge FRCS

Mr. Peter Burge then spoke to the meeting using slides and X-rays to illustrate his talk, plus samples of bones and fixators. He is an arm specialist with experience of the problems HME presents in the arms. First he told us that in medical terms the arm is the part between the shoulder and the elbow and the forearm is the part below the elbow. Problems in the arm are mainly just the existence of exostoses on the humerus and are usually cosmetic. Problems in the forearm, however, which is affected in 30% to 60% of people with HME, are the commonest cause of functional impairment in this condition.

The ulna is the bone on the small finger side of the forearm (we were shown X-ray pictures). This bone is wider at the elbow and narrower at the wrist. The radius is on the thumb side of the arm and is smaller at the elbow and thickest at the wrist. Normally there is a range of rotation of 180°. The two bones are linked by ligaments along their length.

Half an inch from both ends of the radius and ulna is a plate of cartilage right across the bone. It is at these points that the cells proliferate and new length is gained. They are known as the growth plates. Commonly, in HME, ulnar growth is reduced and instead of being at a slight outward angle to the arm, the forearm is straight or has an inward bow. We were shown X-rays showing an exostosis and typical HME curve. It is also possible for the head of the radius to pop out of joint (become dislocated) at the elbow. This is not uncommon in affected adults. We were shown a picture of a severely affected forearm.

Forearm Problems in HME

These can include:

• Swelling due to exostosis - usually on the ulna
• Loss of rotation - can make it difficult to hold out palm, say to accept change
• Inadequate growth - in one bone only causes bowed forearm, in both bones causes short straight forearm
• Ulnar deviation at the wrist
• Radial head dislocation at the elbow
• Pain - more problems are found in adults than in children and an operation may be necessary

Mr Burge then described two contrasting approaches to forearm problems in HME.

The Conservative Approach
In favour of this is:

• Young people are adaptable
• People accept the deformity
• Deformity is consistent with good function
• Removal of dislocated radial head if painful
• Deterioration in later life has not been reported

This list is based on findings reported by Manske et al, St Louis, USA, 1997.

The Aggressive Approach:

• Deformity is often progressive
• Deformity causes weakness, loss of function and poor appearance
• Recommend early and aggressive treatment to prevent disability

These findings were reported by Peterson H, Mayo Clinic, USA, 1994.

One reason for the difference between the two approaches might be that patients seen at the Mayo Clinic tend to be the more severely affected.

In the United Kingdom orthopaedic consultants take an approach somewhere in between these two.

Treatment of Forearm Problems

The options include:

• Remove exostoses
• Lengthen short ulna
• Shorten radius
• Staple radial growth plate (to slow growth)
• Remove dislocated radial head (adults only)

The commonest forms of treatment are the first two. Some options may be undesirable because they may reduce the length of an already short forearm.

Removal of Exostoses:

• May be helpful to relieve persistent pain or to remove a large swelling
• It is sensible to weigh up the amount of disability versus the scar that may result
• No evidence that removal increases growth of the affected bone

Forearm Lengthening:

• For progressive loss of length of the ulna
• In childhood, not in adults
• Long treatment time involved
• May need to be repeated
• May help to keep radial head in joint

Fixator with key

We were shown the fixator device used for lengthening bones which has a key to turn the pins. We also saw an X-ray picture showing the device in place.

The bone is broken and is then left a week for the healing process to begin. The bone is then pulled apart by 1 mm a day. The key has to be turned 4 times a day at regular intervals to achieve this. 3.5 cm of growth can be produced with the device we were shown. The aim is to slightly overdo the lengthening. Turning takes place over about 5-6 weeks and then the device has to be left in place for a further 5-6 weeks for healing to take place. The whole procedure takes about 6 months. However, after a year or two, it is not possible to see where the device was, even on X-ray.

X-ray of forearm with fixator in place

The body deploys it's own healing process to remodel the radius which changes in response to the forces on it. Children's joints adapt well to the new geometry. There may be some pain and stiffness at first, due to stretching of the nerves and other soft tissues, but this is temporary. The procedure cannot be done in adults as growth is complete and the joints and other tissues would not adapt. The procedure can be done at any age up to 11, this limit allowing time for the joints to adjust before the end of growth. It is not carried out unless the forearm is getting progressively worse and the risks and benefits have to be weighed up. There are no real direct risks but it is inconvenient to have the device in place and it involves a lot of hospital visits over a minimum of 6 months.

Helen reported that her son had had it done aged 5 and she would recommend it to anybody with doubts about their child having it done. Children can write with the device in place.

Forearm Lengthening Technique:

• External fixation device is fitted and bone is cut
• Gradual distraction begins after 1 week - 0.5 to 1 mm per day in 4 increments, ¼ turn each time spaced evenly over 24 hour period
• Phase 1 - gain length
• Phase 2 - wait for secure healing
• Phase 3 - protective cast or splint

Forearm Lengthening Problems:

• Pin track infection/loosening
• Slow healing
• Premature healing
• Loss of rotation of forearm, usually temporary but can take months to regain full function

Conclusions:

Treatment generally works well, but it involves many hospital trips and is inconvenient for the child. Forearm lengthening is done in many centres world wide. Six cases have been done in Oxford and experience is still being gained. In the United Kingdom the procedure is available in most large teaching hospitals, for example in Oxford, Southampton, Birmingham and London. If a particular hospital does not do it they will know the nearest centre that does and will be able to make a referral or else monitor the patient and refer at a later date.

The inability to touch the shoulder indicates stiffness in the elbow. This and the loss of a slight curve in the arm are indications that treatment is necessary. The procedure can be done if the radius is already dislocated but it is difficult to put it back into joint even with surgery. The radial head can be removed when growth is complete but not before, as this may affect growth. 90% patients have the problem of a short ulna compared to 10% with a short radius. It is easier to shorten bones than to lengthen them but in HME, where the limbs are already shorter, it is undesirable to shorten the bones still further.

Sometimes adjusting clothes to fit is helpful on its own. Sometimes hands can be straightened by removing a wedge of bone from the wrist. This can help a lot with self image and from a cosmetic point of view because the hand is so visible. Surgery can cure pain and straighten limbs but so far it is not so good at improving function. Nowadays X-rays are kept to a minimum and ultra sound is a useful alternative.