73. Forearm
From Primary Surgery
73.1 Introduction
The results of treating fractures of the forearm are often so bad that the literature about them is only exceeded by that on the hip. Fractures of the forearm are mostly the result of a direct blow. When a patient's bones are broken, the muscles attached to the fragments pull them out of place, and make treatment particularly difficult.
(1) Either forearm bone can fracture alone. (2) Both ones can fracture simultaneously, usually in their middle thirds. When this happens in a child, the fracture is likely to be greenstick. (3) Either bone can fracture, and at the same time, the upper or the lower joint between them can dislocate. If the radius fractures, the lower radio-ulnar joint may subluxate (Galeazzi fracture). If the proximal third of the ulna fractures, the head of the radius may dislocate anteriorly Monteggia fracture). These dislocations are often missed, so always include a patient's wrist and his elbow on a forearm film, particularly if the fragments are overlapped or angulated.
EXAMINING THE FOREARM Palpate the whole of the subcutaneous
border of the patient's ulna, and the lower two
thirds of his radius.
Squeeze his radius and ulna together in the lower part of his forearm. If this hurts him, he probably has a fracture.
Examine the head of his radius (72.1) (Monteggia fracture) and his inferior radio-ulnar joint (Galeazzi fracture) to make sure they are not dislocated.
Examine his elbow and his wrist.
X-RAYS should include the patient's wrist and a lateral view
of his elbow. A line through the long axis of his radius should
pass through his capitulum in both views, as in Fig. 73-4.
| X-RAY THE PATIENT'S WRIST AND HIS ELBOW |
Most fractures of the radius and all fractures of both bones
are usually treated by open methods where skills and facilities
are good. But if you are not a skilled surgeon, and your facilities
are not perfect, closed methods are more likely to give your
patients adequate function at minimum risk (69.3). Isolated fractures
of the ulna are more easily treated than those of the radius,
because the muscles attached to the ulna are much less likely
to displace its fragments.
Closed methods of reduction use the long arm cast described below, modified by varying the position of the patient's wrist to suit the needs of particular fractures. If both his bones are broken you can gently squeeze the cast from front to back to correct the angulation of the fragments towards one another. A forearm cast is heavy, so hang it from his neck. If you don't, its weight may redisplace the fragments, or press on his radial nerve and paralyse it. Most casts for forearm fractures, especially those for fractures of both bones, must go above the elbow.
CASTS FOR THE ARM
A LONG ARM CAST The first cast on a forearm fracture should always be a long arm cast. Apply a single layer of cotton wool to the patient's arm, then put cotton pads over the bony points around his elbow, and in his antecubital fossa.
Apply the cast from just below his shoulder to his MP joints. Hold his elbow at 90°, and his thumb and fingers free. His thumb must be free enough to touch his little finger. If his thumb is held out in abduction, it will be so stiff when you remove the cast as to be temporarily useless.
Carry the cast to the base of his thumb and knuckles and to his distal palmar crease. If you carry it beyond this point, he will not be able to move his fingers.
Adjust the rotation of his forearm as is best for each particular fracture, as described later (73.5).
Take a narrow plaster bandage, mould a plaster eye over the centre of gravity of the cast, and tie it with a comfortable collar around his neck.
CAUTION ! If the fracture is recent, split the cast (70.4, 70.6).
Alternatively: (1) Instead of applying a circular cast, apply anterior and posterior slabs and bandage them in place. Or, (2) apply plaster to the patient's forearm first, and when this has set, complete the cast above his elbow.
A FOREARM CAST Use this to protect a patient's forearm
bones from refracture for a few weeks after they have united,
until they have consolidated.
73.2 Isolated fractures of the shaft of the ulna
A blow on the back of the patient's forearm breaks his ulna. The fracture is complete and transverse, with minimal displacement. There may be slight angulation and bowing, but there is no shift, no overlap, and no rotation. The subcutaneous border of his ulna is tender and swollen over the fracture. These fractures are common and easily treated, because the intact radius makes a good splint.
FRACTURES OF THE ULNA
Make sure that the head of the patient's radius is not dislocated by including his elbow in a lateral X-ray. If it is, he has a Monteggia fracture (73.3).
THE UPPER TWO THIRDS Treat him with active movements in a sling until he can use his arm without discomfort.
THE LOWER THIRD A small plaster slab may ease his
discomfort.
Protect both types of fracture in a sling for 5 weeks, then test for union by squeezing his radius and ulna towards one another.
If there is no tenderness, he can use his arm for anything he likes, except heavy manual work.
If there is tenderness, the fragments have not yet united, so apply a skin tight cast from his elbow to his wrist, and continue active movements. Leave it on for five weeks, by which time it should have united.
73.3 Fractures of the proximal third of the ulna, with dislocation of the head of the radius (Monteggia's fracture)
In places where there is much personal violence, this is a common and nasty adult's fracture; elsewhere it is a rare children's fracture. An adult raises his arm to protect his head from a blow, and receives the full force of the blow on his forearm, breaking his ulna and dislocating the head of his radius. The important part of the injury is the dislocation of the head of his radius, not the fracture of his ulna, which is usually broken in its upper third. Rarely, his ulna does not break, and dislocation of the head of his radius is his only injury. When his ulna does break, the fracture may be greenstick, and its fragments may only bow. Or, it may break completely and its fragments overlap, as in Fig. 73-4.
If you suspect that a patient has dislocated the head of his
radius, take an AP and a lateral view, because you may see the
dislocation in one view, but not in the other. A line through
the centre of his radius should pass through his capitulum. If
the fragments of his broken ulna overlap, either his radius must
also be fractured, or its head must be dislocated.
Unless the dislocation of the head of a patient's radius is reduced, he will never be able to bend his elbow again. Closed reduction is usually possible in children, and sometimes in adults. Try to reduce this injury early, because the longer you delay the more difficult it will become.
MONTEGGIA'S FRACTURE
The method is the same, whether or not the patient has fractured his ulna.
Anaesthetize the patient and find two assistants. Extend his arm and supinate it. Ask one of your assistants to hold his upper arm (1, in Fig. 73-4) and your other assistant to exert traction on his wrist (2).
While your two assistants are maintaining traction, press the distal end of the proximal ulnar fragment posteriorly (3). Then try to press the head of the patient's radius posteriorly (4).
Next, while still pressing the head of his radius (5), flex his supinated forearm (6). The head of his radius should reduce with a `slunk; and his ulna should finally straighten completely as it does so.
Apply anterior and posterior slabs directly to his skin from his axilla to the heads of his metacarpals, with his elbow flexed at about 80° and his forearm supinated. Bandage the slabs in place. They will help to keep the head of his radius in place.
Start finger and shoulder exercises immediately. CAUTION ! The head of the radius is unstable after this injury and it can redisplace, so X-ray him at weekly intervals. Hang the slabs from his neck for 3 weeks, remove them, change them for a collar and cuff, and add elbow movements to those he i s already doing. Movements will take months to return-don't force them.
IF REDUCTION OF THE RADIAL HEAD FAILS OR THE
PATIENT PRESENTS LATE, management depends on his age.
If he is an adult, refer him for immediate open reduction,
as described below. If the head of his radius is not reduced,
he will never be able to bend his elbow again.
If he is a child, and the injury is less than 3 months oId,
refer him. If the injury is more than 3 months oId, leave him.
Normal movements will usually return in spite of the unsightly
hypermobility of his radial head.
IF REDUCTION OF THE ULNA FAILS so that it remains
seriously angulated, refer him.
DIFFICULTIES WITH A MONTEGGIA FRACTURE
If the HEAD OF THE RADIUS WILL NOT REDUCE, it may have gone through a hole in the capsule, and so be irreducible by closed methods. Open reduction will be necessary, so refer the patient immediately. If the dislocation is an old one, reduction may be impossible by any method. If he is an adult, it may then be necessary to excise the head of his radius.
If a Monteggia FRACTURE IS OPEN, do a careful wound
toilet. If there is an haemarthrosis, aspirate the patient's elbow
( Fig. 72-4), and reduce the fragments into the best position
you can. Provide skin cover by delayed primary closure or grafting,
and then start early active movements.
73.4 Fractures of the shaft of the radius with dislocation of the lower radio-ulnar joint(Galeazzi's fracture)
These are rare, difficult fractures. In children the fracture of the radius is greenstick, and the only displacement is an anterior bow. Adults have a complete fracture of the radius in which the distal radial fragment tilts, shifts anteriorly, overlaps, and inclines towards the ulna. At the same time the distal end of the ulna dislocates from both the radius and the carpus, and displaces dorsally to make an ugly bulge on the back of the wrist.
Incomplete Galeazzi fractures (children) cause a child's lower forearm to bow forwards. He is tender over a greenstick fracture of his radius, usually in its distal third. The distal end of his ulna is also tender. Closed reduction is usually straightforward.
Complete Galeazzi fractures (adults) are often open, with the skin punctured on the front or back of the patient's foreann, and his radius sticking through it. There is usually no need to explore the wound because there is no dead tissue to remove. Instead, seal the puncture hole with a dressing, before you reduce the fracture.
GALEAZZI'S FRACTURE
INCOMPLETE GALEAZZI FRACTURES
If the fracture is in the distal third of the radius, even a 45° angulation in a small child does not matter, and soon corrects itself as he grows. The younger he is, and the closer the fracture to the epiphysis, the greater the angulation you can accept.
If the fracture is higher up in the middle third of the child's radius, moulding is less rapid and less complete, especially if he is older. So anaesthetize him, and bend his radius back into place. This reduces the fracture and the dislocation of his distal radio-ulnar joint. If the distal end of his ulna happens also to have been fractured, the overlap of the radius usually remains.
Apply a long arm cast with his elbow at 90°, his arm in mid-rotation, and his wrist slightly palmar flexed.
After 6 weeks, replace this cast by a shorter one extending from the upper part of his forearm to above his knuckles. This will hold his radius straight and prevent him dorsiflexing his wrist. Leave this short cast on for 6 weeks.
COMPLETE GALEAZZI FRACTURES
CLOSED REDUCTION Anaesthetize the patient, using a relaxant if possible. Then suspend his forearm over the side of the table from a drip pole as in Fig. 73-10.
Reduce the fracture until his forearm looks normal, apply a long arm cast, and mould it to give it a flat cross-section as in Fig. 73-9. Complete the cast, and include a ring in it.
X-ray him again, and consult Fig. 73-5. If his radial styloid I s distal to his ulnar styloid, reduction is adequate. If his ulnar styloid is distal, reduction is not adequate.
If reduction is adequate, continue treatment as for a midshaft
fracture of the radius and ulna (73.6).
If reduction is not adequate, his radius slips anteriorly into its displaced position, and his ulna slips distally to the head of his radius. If possible, refer him within the first week for open reduction of his radius. This will correct the position of his ulna at the same time.
DISASTER WITH A GALEAZZI FRACTURE
If the FRACTURE WAS MISSED, both bones will have united solidly, and the lower end of the patient's ulna will stick out as a lump on the back of his wrist, which will be stiff and painful. Refer him for the excision of the lower end of his ulna.
73.5 Isolated midshaft fractures of the shaft of the radius
The fact that a patient's radius rotates makes its fractures much more difficult to treat than those of his ulna. If there is no overlap, no reduction is necessary, and you can treat him with a plaster forearm splint. But if the fragments overlap, treatment is more difficult, because his intact ulna prevents you distracting and angulating his broken radius. Closed methods may work, but if they fail, this fracture needs open reduction and internal fixation. The radius usually breaks through its proximal third. If it breaks through the junction of its middle and distal thirds, closed methods are even less likely to succeed.
A fracture allows the proximal fragment of the radius to rotate on the distal one. You cannot alter the position of the proximal fragment, so all you can do is to try to find out where it is, and line up the distal fragment with it, before you immobilize them both.
The supinating muscles, biceps, and supinator are attached to the proximal end of the radius, and the pronating muscles, pronator teres, and pronator quadratus are attached to its distal end. In fractures above the insertion of pronator teres (half-way down the radius) the supinators supinate the proximal fragment. In more distal fractures its position is more variable. There are several ways of finding out how far the proximal fragment has rotated.
(1) You can assume that, (a) in fractures of the proximal third of the radius (above the insertion of pronator teres), the proximal fragment will be in full supination, and (b) that in fractures of the distal two thirds below the insertion of this muscle, it will have pulled the proximal fragment into mid-pronation. This is a useful compromise because a forearm fixed in mid-pronation is only a minor disability, whereas one which becomes fixed in full supination will be a considerable handicap.
(2) The most accurate way is to take an AP X-ray of the upper end of the patient's injured radius, and use the position of his radial tuberosity as a guide to how far the proximal fragment has rotated. Either, (a) use Fig. 73-8 as a guide, or (b) better, if you have plenty of X-ray film and can spare it, take several X-rays of his normal radius, in various degrees of pronation and supination, and find the position which best matches the fractured one. When you immobilize it, do so in this position.
Some surgeons routinely convert isolated greenstick fractures of the radius and greenstick fractures of both bones into complete ones. If this is done, they are said to be less likely to redisplace inside the cast after reduction.
| IMMOBILIZE PROXIMAL THIRD FRACTURES IN SUPINATION IMMOBILIZE MIDDLE AND DISTAL THIRD FRACTURES IN MID-PRONATION |
ISOLATED MIDSHAFT FRACTURES OF THE RADIUS
Examine the patient's lower radio-ulnar joint carefully to make sure it is not abnormally prominent and dislocated. If it is, he has a Galeazzi fracture.
ADULTS WITH AN ISOLATED VIDSHAFT FRACTURE OF THE RADIUS
If possible, refer the patient for internal fixation, particularly if: (1) the fracture is at the junction of the middle and distal thirds, or (2) you need to immobilize his forearm in either of these extreme positions, because subsequent rotation is more likely to be limited.
If you cannot refer him, proceed as follows.
WITHOUT OVERLAP No reduction is necessary, but the
fragments need a splint to stop them rotating, so apply a long
arm cast. Use the methods described above to decide the correct
degree of pronation and supination in which to
immobilise his arm. Flatten the cross section of his cast as in Fig. 73-9. Don't pad it, except over the bony points at his
elbow.
Start active finger movements immediately.
WITH OVERLAP Make one or even two attempts to reduce
the fracture by the gentle 'squeezing grip', shown in Fig. 73-
9. If you fail, refer him.
CAUTION ! Don't grip too hard, or you may impede the circulation in his arm.
CHILDREN WITH AN ISOLATED VIDSHAFT FRACTURE OF THE RADIUS
Management depends on the degree of angulation.
If angulation is minimal, bandage the child's arm.
If angulation is more than minimal, anaesthetize him, suspend his forearm, reduce the fracture, and apply a cast as above. To prevent the fracture slipping subsequently, slightly overcorrect the position.
CAUTION ! More than a minimal degree of angulation at the centre of the bone is not acceptable. If necessary, break the bone completely and realign the fragments.
Alternatively, apply the cast. While it is still wet and soft, quickly snap the greenstick fracture through completely. Hold the fragments reduced until the cast is hard.
| THE POSITION OF FUNCTION IS THE POSITION OF MID-PRONATION |
73.6 Midshaft fractures of the radius and ulna
These are common and difficult fractures: (1) The fragments are difficult to align, (2) they displace easily, and (3) cross-union may occur, and prevent the patient rotating his forearm. If he is under 18, open reduction and internal fixation are unnecessary, but in older patients this is one of the fractures which is generally treated by open methods-if skills and operating conditions are good enough. They seldom are in the district hospitals for which we write. So refer the patient immediately if you can; if necessary, internal fixation can be delayed 10 days. If you wait, make sure you correct overlap by applying traction meanwhile.
If you cannot refer the patient, treat him as we describe. Make quite sure that if rotation will later be limited, his forearm will at least be fixed in the most convenient position for him. This is in 45 ° of pronation, as in Fig. 73-1. For many patients a forearm fixed in this position is only a minor disability, because movements of the shoulder can compensate to some extent for pronation and supination of the forearm. Fixation in any other position is a completely unnecessary tragedy. Bowing may be ugly, but it is much less serious.
73.6a Greenstick midshaft fractures of the middle third of both forearm bones
These cause an obvious bowing of a child's forearm. Correct angulation carefully, because the fracture is in the centre of the bone and remodelling will not correct it later (69.6). Some surgeons deliberately break greenstick fractures through completely with the aim of reducing the risk of displacement recurring.
| APPLY THE CAST IN MID-PRONATION |
GREENSTICK FRACTURES OF BOTH FOREARM BONES
Anaesthesia is kind but not essential. Ketamine is satisfactory (A 8.2).
If the fracture is undisplaced, apply a plaster slab.
If the fracture is displaced, apply a circular cast from the child's knuckles to the middle of his upper arm with his forearm in mid-pronation. While the cast is still soft, straighten his forearm. Correct angulation carefully, especially in the lateral (coronal) plane, which moulds even less readily than angulation in the anteroposterior (sagittal) plane.
CAUTION ! Split the cast. If you don't split it, he would be much safer with a plaster backslab. Some surgeons routinely treat displaced greenstick forearm fractures with slabs.
Start active movements of the child's shoulder and fingers as soon as possible.
X-ray him during the first 3 weeks, look for angulation, and if necessary, correct it under anaesthesia, as described below for angulation in complete fractures.
After 5 weeks, remove the long arm cast, and test for clinical union. If the fracture has united, replace it by a sling, and continue active movement. If it has not united, reapply the cast.
Alternatively, break his bones through with a sharp bending force, and slightly overcorrect the deformity. Suspend his forearm as for a complete fracture, apply a long arm cast, and be sure to split it!
73.6b Complete fractures of the middle third of both forearm bones
If both a patient's forearm bones are broken in the middle, his forearm is free to bend in the middle. You can easily correct this angulation; the difficult part is separating the fragments when they have inclined towards one another. In the following method the patient's arm is suspended vertically from a drip stand while a cast is applied. This: (1) prevents the fragments bending under the influence of gravity while the cast sets, (2) allows you to apply the cast in a single stage, and (3) lets you correct the inclination of the radius and ulna towards one another by gently squeezing the cast anteroposteriorly while it sets. This flattens its cross section, compresses the muscles of the patient's forearm, and so makes them push the two bones apart.
This is a potentially dangerous cast, so remember to split it as described below. If you split it correctly, you will not lose reduction. Never use an ordinary backslab, which is quite ineffective in complete fractures.
The details are critical. If you neglect them, your results will be bad. Try to enthuse the patient with the part he can play in getting his bones to unite by using his fingers early and actively. The muscles of his fingers arise from his broken bones, so active finger exercises will cause small movements of his muscles inside the cast, and promote union. Tell him to do up his own buttons, to feed himself, and to do anything he can with his hands.
| GIVE THE CAST A FLATTENED CROSS SECTION |
COMPLETE FRACTURES OF THE MIDDLE THIRD OF THE RADIUS AND ULNA
If you can refer the patient to an expert for open reduction, do so.
CAUTION ! If there Is: (1) much swelling, or (2) weakness of finger movements, suspend the patient's arm from a drip stand using metacarpal traction (Fig. 70-13), or skin traction (70.10), until these signs have subsided. If he is unconscious, apply metacarpal traction until he recovers.
Anaesthetize him. Ketamine is satisfactory (A 8.2). Find an assistant. if a spicule of bone has punctured his skin, wash and dress it before attempting reduction.
Find two assistants.
If the patient is already in metacarpal traction, leave it on
until you have completed the cast.
If he is not In metacarpal traction, use a bandage and clove hitch knots to suspend his thumb and middle finger from a drip stand, so that you can later pass a plaster bandage across his palm.
Lie him horizontally close to the edge of the table. Adjust the height of the drip stand, so that his forearm is vertical, with his elbow flexed at 90° well clear of the table.
If any overlap remains, reduce it by applying a sling and a weight of 5 kg or more to his upper arm. Or, ask your assistant to press downwards on his arm, or to hold his elbow and pull it downwards.
Except in very fat, muscular, or swollen arms, you should be able to feel when the fragments are aligned. Traction usually reduces any overlap, but if it does not, proceed as follows.
If the patient is an adult, increase the deformity by angulating the fragments, getting them to hitch, and then straightening them, as in Fig. 73-13.
If he is a child, perfect end to end apposition is not necessary, and some overlap is acceptable.
CAUTION I if you fail to correct the angular or rotational deformity in an adult or a child, loss of pronation and supinetion may follow.
APPLY A LONG ARM CAST When the arm looks and feels
good, apply the cast. Apply the forearm part of the cast first,
with the sling and weight still attached to the patient's upper
arm to steady his elbow. First, apply a single layer of wool
to his arm, then put cotton wool pads over the bony points
round his elbow. These will make the cast more comfortable,
and make rehabilitation easier.
Use cold water to make the plaster set slowly. First apply a cast from the patient's knuckles to his lower axilla. Apply it with his forearm in that position of rotation in which reduction is most easily obtained. Preferably apply it in mid-pronation, so that if rotation is limited later, it will be in the most useful range. Bring the cast as far as the iP joint of his thumb, and his micipalmar crease. This will help to prevent his thumb moving and dislodging the lower fragment of his radius. The cast must allow free movements of his fingers, and of the distal phalanx of his thumb.
As the cast sets, squeeze it lightly between your hands from front to back, to flatten it slightly and to separate his radius and ulna. Some surgeons mould anteroposterior grooves in the cast to separate the two bones.
Remove the sling and continue the cast to his axilla. Build a loop into the cast and support it in a sling. Later, support the cast with a sling through the loop.
CAUTION ! ALWAYS split the cast! Do this while it is still soft (70.6). Make a single cut along its ulna side, from the patient's hand to his axilla. if his arm is painful, or he is unable to move his fingers, spread the cast (70.6), and treat him as described below.
X-ray him immediately after reduction. if this is unsatisfactory, have one further attempt at reduction. if this fails, refer him for internal fixation.
If reduction is unsatisfactory, and you cannot refer him for internal fixation, accept the overlap and allow his forearm to heal in mid-pronation, which is the position of function. Provided his arm is in this position, he will probably have reasonable function, even if there is overlap.
POSTOPERATIVE CARE Watch the circulation in his fingers
carefully. The compartment syndrome described below can
occur.
CAUTION ! Can he move his fingers? is passive extension painful?
Start shoulder and finger exercises immediately. Tell him to put his hand as far behind his head as he can. This will exercise his shoulder. Encourage him to use his hands.
X-ray him at 2 weeks, and again at 4 weeks, and make sure that the rotation has remained in the position of function. if necessary, correct any angulation.
You can correct mild angulation by wedging (70.7), but a change of cast is safer. if you decide to wedge it, do this carefully, because it can precipitate Volkmann's ischaemic contracture. More severe angulation will need a new cast. After 4 weeks the bones will have united and it will be too late to do any correction.
If the patient is an adult, the cast must remain intact for
6 to 8 weeks. This is a long time, so it must be a good one.
Examine for clinical union after 8 weeks. Gently spring his
forearm bones. if these angulate or are tender, reapply the
cast. Otherwise, put his arm in a sling, and encourage him
to move his elbow and rotate his wrist.
If the cast needs to be changed for any reason, such as looseness, suspend his arm by his fingers to prevent the fracture angulating while you apply a new one.
If he is a child, keep his long arm cast on for 4 to 6 weeks,
and then examine for union. He is very likely to refracture his
arm, so apply a cast for another 6 weeks. This time, apply it
to his forearm only. When you remove it, put his arm in a sling
and encourage active movements.
DIFFICULTIES WITH MIDSHAFT FRACTURES OF THE FOREARM
If PAIN OR LOSS OF FINGER MOVEMENT DEVELOPS, split the cast if you have not already done so, spread it (70.6), and treat him as described in Section 73.7. The soft tissue swelling may be causing ischaemia which is much more serious than loss of position. You can correct this later by applying another cast.
If his FOREARM BONES WILL NOT UNITE, refer him. Reasons include: (1) sloppy plaster technique resulting in failure to immobilize his bones, (2) the failure to exercise his fingers, (3) not getting satisfactory reduction, soft tissue injury, or interposition and infection.
If his FRACTURED ULNA IS OPEN, there will probably be only a spike of bone projecting through his skin. Clean it and pull it back, or nibble it away. Toilet the wound, and suspend his forearm with Kirschner wire traction through his metacarpals (70.11) or skin traction on his fingers (70.10). Let his forearm hang vertically, so that the weight of his arm reduces the fracture. When the wound has begun to heal, treat him as for a closed fracture.
| WATCH THE CIRCULATION IN HIS HAND CAREFULLY! HE MUST KEEP MOVING HIS FINGERS! |
73.7 The compartment syndrome in the forearm
If a patient with a forearm fracture suffers from the four Ps= pain, paraesthesiae, pallor (if he is Caucasian), and paralysis, suspect that he has developed the compartment syndrome and may be in danger of its sequel, Volkmann's ischaemic contracture (70.4). This is more common with fractures of the forearm than it is with supracondylar fractures (72.8, 72.9).
The critical test is pain on passive extension of the patient's fingers. A normal radial pulse does not rule out ischaemia. If he cannot extend his fingers, there is compression in the anterior compartment of his forearm. If he cannot flex them, there is compression in the posterior compartment (rare). If, when you have removed the cast, the circulation and movement of his fingers does not rapidly return, decompress his forearm as described below. If possible, operate within a few hours of the onset of symptoms, but if he presents late, be prepared to operate even weeks later. If his muscles feel tense, swollen, and almost woody hard, decompression is urgent. Unfortunately, in splitting the cast you will lose reduction, so as soon as his circulation returns, apply skeletal traction. Later, reduce the fracture again, and reapply the cast.
Occasionally, a patient with a fractured forearm has signs of the compartment syndrome even before a cast is applied. It can also follow soft tissue injuries of his forearm, especially stab wounds, but sometimes even muscle contusion, as in the case below.
| ASLAM (43 years) struck his forearm while water-skiing but did not fracture it. Eight hours later it became acutely painful and he could not extend his wrist or fingers. He consulted his neighbour, an orthopaedic surgeon, who decompressed his forearm within the hour, from wrist to elbow, as in Fig. 73-I1, leaving his skin and fascia open. Dark swollen muscle bulged out of the wound. He was discharged the following morning, and his incision was closed 5 days later. He recovered completely. LESSONS (1) Remember the compartment syndrome. A happy outcome followed what might have been a major tragedy after a minor injury. (2) Be quick! Immediate decompression is imperative. |
| INDURATION OF THE MUSCLES IS PATHOGNOMONIC |
THE COMPARTMENT SYNDROME IN THE FOREARM
If a patient in a forearm cast complains of pain, believe him, and if he has a cast on, split it, spread it, and elevate his arm. if this does not rapidly relieve his symptoms, remove it. if the syndrome is advanced his arm will swell and become red. if his symptoms do not improve rapidly, proceed as follows.
Make an incision from his medial epicondyle to the ulnar end of the flexor crease on his wrist, as in A, Fig. 73-11. incise the fascia over his flexor carp! ulnaris, and retract this muscle medially. Retract his superficial flexor muscles laterally, and incise the fascia over his deep flexors. Decompress each muscle by making a longitudinal incision through its sheath, carefully avoiding its nerve. The pale compressed muscle tissue will bulge up gratefully, as you release the pressure in its sheath. if you have acted in time, a conspicuous hyperaemia will follow. if you are much too late, the deep flexor muscles will be yellow and necrotic.
CAUTION ! Don't cut his ulnar nerve or his ulnar artery. The nerve lies close to the artery underneath his flexor carp! ulnaris, and between it and his deep flexors.
Put Kirschner wires through his second, third, and fourth metacarpals (70.12), suspend his arm vertically, and leave the wound open and unsutured, under a vaseline gauze or a hypochlorite dressing.
Continue to apply traction. This usually reduces the fracture.
Leave the fascia open. if you can close the skin easily, do so. if you cannot close the skin easily, apply a gauze dressi ng and attempt secondary closure 5 days later. Apply a cast over the graft.
DIFFICULTIES WITH THE COMPARTMENT SYNDROME
If you have NO KIRSCHNER WIRE, decompress the patient's forearm, splint it with a plaster backslab, and refer him immediately. If the SYNDROME iS ADVANCED when you decompress his forearm, maintain a high alkaline urine output, to assist the excretion of the myoglobin released from the necrotic muscle, and watch for renal failure (53.3).
If a CONTRACTURE DEVELOPS, apply splints to minimize the deformity as much as possible.
| DECOMPRESSING THE FOREARM IS AN ACUTE EMERGENCY |
73.8 Fractures of the lower quarter of the radius and ulna (usually young children)
In this common injury a young child breaks both his bones transversely about 4 cm above his wrist. The fracture is usually greenstick, and the lower fragments angulate radially and anteriorly. Sometimes his ulna remains intact, and the only Xray sign is buckling of the cortex of his radius on one side wrinkle fracture). If the fracture is complete, both lower ragments displace behind the shafts and produce a dinner fork deformity. The lower quarter of the forearm bones readily remodel, particularly in very young children, so that unless there is a significant degree of angulation, no reduction is necessary. Opinions vary as to whether you should reduce overlap or not. If necessary you can leave it. The younger the child, the more the displacement you can accept. See also Section 69.6 on the bony injuries of young children.
FRACTURES OF THE LOWER QUARTER OF THE RADIUS AND ULNA
ACCEPTABLE DISPLACEMENT This includes most greenstick fractures, especially those with any slight buckling of the cortex of the bone. (1) Angulation less than 30° in the plane of the wrist. (2) Lateral displacement without shortening. (3) Some surgeons also accept overlap.
Protect the child's arm with a slab and a crepe bandage, put it in a sling, and start active movements immediately.
UNACCEPTABLE DISPLACEMENT (1) More than 30° of
angulation in the plane of the wrist. (2) Rotation. (3) Overlap
is sometimes considered unacceptable.
In greenstick fractures anaesthesia is not essential. In complete fractures anaesthetize the child, preferably with ketamine.
CLOSED REDUCTION OF FRACTURES OF THE LOWER QUARTER OF THE RADIUS AND ULNA
If the lower fragment of the radius is angulated, straighten it. Disregard the ulna.
If you decide to reduce the overlap, increase the angulation as far as possible, press on the base of the distal fragments when they are fully angulated, get the ends to hitch, and then straighten and distract them as in Fig. 73-13. Apply a long arm cast in full pronation.
Consolidation takes 6 weeks. Keep the cast on for the full 6 weeks. The child may fall again and refracture his arm, so apply a forearm cast for another six weeks, and split it!.
IF CLOSED REDUCTION FAILS Attempts to correct overlap
may fail because the pronator quadratus muscle comes between
the bone ends. Management now depends on whether
the child's epiphyseal growth lines have closed or not.
If the epiphyseal growth line at the lower end of the child's radius is open, it is not important if the fragments are end on or not, provided you get his radius reasonably straight. They will remodel themselves completely in 2 years, so some overlap is permissable. If you fail after two attempts, stop. Apply a long arm cast (73.1), and start exercises immediately.
If the epiphyseal growth line is closed, make a second attempt at closed reduction. If this fails, refer him.
Or, you can attempt open reduction if you are experienced. Do this as early as you can, but before 10 days.
OPEN REDUCTION Incise the back of the child's forearm longitudinally over the fracture, separate the muscles, open the periosteum longitudinally, and lever the displaced fragments into place with any convenient instrument, such as MacDonald's dissector. Close the wound in layers, and apply a backslab held in place with a crepe bandage. Take out the stitches a week later, and apply a long arm cast as for an extension fracture of the wrist (74.2), but extending above his elbow with his wrist in a neutral position.
Leave the long arm cast on for 6 weeks, and then apply a forearm cast for 4 more weeks.
73.9 Fracture separation of the distal radial epiphysis (10 to 15 years)
This is the most common epiphyseal injury. The fracture passes partly through the metaphysis of the child's radius, and partly through his epiphyseal line (Salter Harris Type II, Section 69.6). Its lower end usually displaces and tilts radially and posteriorly. There may also be a fracture of the styloid process of his ulna, or a separation of its epiphysis. Fortunately, if you reduce the epiphysis, subsequent disability is rare.
| CHIBWE (7 years) had a minor fracture separation of his distal radial epiphysis. When he was first seen there was no displacement or swelling. A circular cast was applied and he was sent home. Next day he returned complaining of pain and stiff fingers. He was given aspirin and again sent home. Three days later he returned with a gangrenous hand and his forearm muscles sloughing under the cast. His forearm was amputated. LESSONS (1) Always split all circular casts on fresh fractures. (2) Where possible use slabs. (3) Take painful casts seriously. (4) `Think Volkmann's'! |
FRACTURE SEPARATION OF THE RADIAL EPIPHYSIS Give
the child ketamine or a general anaesthetic.
If his radial epiphysis is displaced dorsally, press it firmly
forwards into place. There is no need to exert traction,
because his epiphysis is not impacted. It will hinge forwards
on his intact dorsal periosteum, which will prevent over correction.
Apply a well moulded cast extending above his elbow
with his forearm pronated and his wrist ulnar deviated and
slightly flexed. As always, split it (see the sad story above!).
Leave it in place for 3 weeks.
His epiphysis may redisplace, so X-ray his wrist at short intervals. If it displaces, refer him for internal fixation.
The prognosis is good, even if there is slight residual angulation after reduction.
