Ch 73 Forearm

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Ch 73 Forearm

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<ul><li><p>CHAPTER 73</p><p>The forearm</p><p>73.1 Introduction</p><p>The results of treating fractures of the forearm are often sobad that the literature about them is only exceeded by thaton the hip. Fractures of the forearm are mostly the result of adirect blow. When a patients bones are broken, the musclesattached to the fragments pull them out of place, and maketreatment particularly difficult.</p><p>(1) Either forearm bone can fracture alone. (2) Both onescan fracture simultaneously, usually in their middle thirds.When this happens in a child, the fracture is likely to begreenstick. (3) Either bone can fracture, and at the sametime, the upper or the lower joint between them can dis-locate. If the radius fractures, the lower radioulnar jointmay subluxate (Galeazzi fracture). If the proximal third ofthe ulna fractures, the head of the radius may dislocate an-teriorly Monteggia fracture). These dislocations are oftenmissed, so always include a patients wrist and his elbow on aforearm film, particularly if the fragments are overlapped orangulated.</p><p>EXAMINING THE FOREARM Palpate the whole of thesubcutaneous border of the patients ulna, and the lower twothirds of his radius.</p><p>Squeeze his radius and ulna together in the lower part ofhis forearm. If this hurts him, he probably has a fracture.</p><p>Examine the head of his radius (72.1) (Monteggia frac-</p><p>0</p><p>45</p><p>PRONATIONNEUTRALSUPINATION position offunction</p><p>this is the mostuseful positionPRONATION AND</p><p>SUPINATION</p><p>Fig. 73.1: IF PRONATION AND SUPINATION ARE LIKELY TO BELIMITED by the nature of the fracture, the patients hand will be mostuseful to him if his forearm is in a position of midpronation. Kindly con-tributed by John Stewart.</p><p>ture) and his inferior radioulnar joint (Galeazzi fracture) tomake sure they are not dislocated.</p><p>Examine his elbow and his wrist.XRAYS should include the patients wrist and a lateral</p><p>view of his elbow. A line through the long axis of his radiusshould pass through his capitulum in both views, as in Fig.73-4.</p><p>XRAY THE PATIENTS WRIST AND HIS ELBOW</p><p>Most fractures of the radius and all fractures of both bonesare usually treated by open methods where skills and facili-ties are good. But if you are not a skilled surgeon, and yourfacilities are not perfect, closed methods are more likelyto give your patients adequate function at minimum risk(69.3). Isolated fractures of the ulna are more easily treatedthan those of the radius, because the muscles attached to theulna are much less likely to displace its fragments.</p><p>Closed methods of reduction use the long arm cast de-scribed below, modified by varying the position of the pa-tients wrist to suit the needs of particular fractures. If bothhis bones are broken you can gently squeeze the cast fromfront to back to correct the angulation of the fragments to-wards one another. A forearm cast is heavy, so hang it fromhis neck. If you dont, its weight may redisplace the frag-ments, or press on his radial nerve and paralyse it. Mostcasts for forearm fractures, especially those for fractures ofboth bones, must go above the elbow.</p><p>CASTS FOR THE ARM</p><p>A LONG ARM CAST The first cast on a forearm fractureshould always be a long arm cast. Apply a single layer of cot-ton wool to the patients arm, then put cotton pads over thebony points around his elbow, and in his antecubital fossa.</p><p>Apply the cast from just below his shoulder to his MPjoints. Hold his elbow at 90, and his thumb and fingersfree. His thumb must be free enough to touch his little fin-ger. If his thumb is held out in abduction, it will be so stiffwhen you remove the cast as to be temporarily useless.</p><p>Carry the cast to the base of his thumb and knuckles andto his distal palmar crease. If you carry it beyond this point,he will not be able to move his fingers.</p><p>1</p></li><li><p>73 The forearm</p><p>A LONGARM CAST B</p><p>A</p><p>C</p><p>this thumb must beable to touch hislittle finger</p><p>suspending thecast avoidspressure on theradial nerve anddisplacement ofthe fragments</p><p>Fig. 73.2: A LONG ARM CAST. Suspending the cast avoids pressure onthe patients radial nerve. Make sure that his thumb is free and able totouch his little finger. Kindly contributed by Peter Bewes.</p><p>Adjust the rotation of his forearm as is best for each partic-ular fracture, as described later (73.5). Take a narrow plas-ter bandage, mould a plaster eye over the centre of gravityof the cast, and tie it with a comfortable collar around hisneck.</p><p>CAUTION! If the fracture is recent, split the cast (70.4,70.6).</p><p>Alternatively: (1) Instead of applying a circular cast, ap-ply anterior and posterior slabs and bandage them in place.Or, (2) apply plaster to the patients forearm first, and whenthis has set, complete the cast above his elbow.</p><p>A FOREARM CAST Use this to protect a patients forearmbones from refracture for a few weeks after they have united,until they have consolidated.</p><p>73.2 Isolated fractures of the shaft of the ulna</p><p>A blow on the back of the patients forearm breaks his ulna.The fracture is complete and transverse, with minimal dis-placement. There may be slight angulation and bowing, butthere is no shift, no overlap, and no rotation. The subcu-taneous border of his ulna is tender and swollen over thefracture. These fractures are common and easily treated, be-cause the intact radius makes a good splint.</p><p>FRACTURES OF THE ULNA</p><p>Make sure that the head of the patients radius is not dislo-cated by including his elbow in a lateral Xray. If it is, he hasa Monteggia fracture (73.3).</p><p>THE UPPER TWO THIRDS Treat him with active move-ments in a sling until he can use his arm without discomfort.</p><p>the patients elbowshould have beenincluded in the Xray!</p><p>ISOLATED FRACTUREOF THE SHAFTOF THE ULNA</p><p>Fig. 73.3: ISOLATED FRACTURES OF THE SHAFT OF THE ULNA.Make sure that the head of the patients radius is not dislocated by includ-ing his elbow in a lateral Xray. If it is dislocated, he has a Monteggiafracture. Unfortunately, this has not been done here!</p><p>THE LOWER THIRD A small plaster slab may ease hisdiscomfort.</p><p>Protect both types of fracture in a sling for 5 weeks, thentest for union by squeezing his radius and ulna towards oneanother.</p><p>If there is no tenderness, he can use his arm for any-thing he likes, except heavy manual work.</p><p>If there is tenderness, the fragments have not yet united,so apply a skin tight cast from his elbow to his wrist, andcontinue active movements. Leave it on for five weeks, bywhich time it should have united.</p><p>73.3 Fractures of the proximal third of theulna, with dislocation of the head of theradius (Monteggias fracture)</p><p>In places where there is much personal violence, this is acommon and nasty adults fracture; elsewhere it is a rarechildrens fracture. An adult raises his arm to protect hishead from a blow, and receives the full force of the blow onhis forearm, breaking his ulna and dislocating the head ofhis radius. The important part of the injury is the disloca-tion of the head of his radius, not the fracture of his ulna,which is usually broken in its upper third. Rarely, his ulnadoes not break, and dislocation of the head of his radius ishis only injury. When his ulna does break, the fracture maybe greenstick, and its fragments may only bow. Or, it maybreak completely and its fragments overlap, as in Fig. 73-4.</p><p>If you suspect that a patient has dislocated the head of hisradius, take an AP and a lateral view, because you may see thedislocation in one view, but not in the other. A line throughthe centre of his radius should pass through his capitulum.If the fragments of his broken ulna overlap, either his radiusmust also be fractured, or its head must be dislocated.</p><p>Unless the dislocation of the head of a patients radiusis reduced, he will never be able to bend his elbow again.Closed reduction is usually possible in children, and some-times in adults. Try to reduce this injury early, because thelonger you delay the more difficult it will become.</p><p>MONTEGGIAS FRACTURE</p><p>The method is the same, whether or not the patient has frac-tured his ulna.</p><p>Anaesthetize the patient and find two assistants. Extendhis arm and supinate it. Ask one of your assistants to hold</p><p>2</p></li><li><p>73.4 Fractures of the shaft of the radius with dislocation of the lower radioulnar joint (Galeazzis fracture)</p><p>MONTEGGIASFRACTURE</p><p>D</p><p>C</p><p>B</p><p>A</p><p>1</p><p>6</p><p>5</p><p>23</p><p>4</p><p>NORMAL linethrough head ofradius passesthrough capitulum</p><p>ulna fractured and overlapped</p><p>radius dislocated</p><p>Fig. 73.4: MONTEGGIAS FRACTURE. A, in a normal arm a linethrough the head of the radius passes through the capitulum. B, in Mon-teggias fracture this line passes through the shaft of the humerus. C, studD, you will need two assistants to help you reduce the head of the radius.After de Palma, with kind permission.</p><p>his upper arm (1, in Fig. 73-4) and your other assistant toexert traction on his wrist (2).</p><p>While your two assistants are maintaining traction, pressthe distal end of the proximal ulnar fragment posteriorly (3).Then try to press the head of the patients radius posteriorly(4).</p><p>Next, while still pressing the head of his radius (5), flex</p><p>his supinated forearm (6). The head of his radius shouldreduce with a clunk and his ulna should finally straightencompletely as it does so.</p><p>Apply anterior and posterior slabs directly to his skin fromhis axilla to the heads of his metacarpals, with his elbowflexed at about 80 and his forearm supinated. Bandage theslabs in place. They will help to keep the head of his radiusin place.</p><p>Start finger and shoulder exercises immediately.CAUTION! The head of the radius is unstable after this</p><p>injury and it can redisplace, so Xray him at weekly intervals.Hang the slabs from his neck for 3 weeks, remove them,</p><p>change them for a collar and cuff, and add elbow movementsto those he is already doing. Movements will take months toreturndont force them.</p><p>IF REDUCTION OF THE RADIAL HEAD FAILS OR THEPATIENT PRESENTS LATE, management depends on hisage.</p><p>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.</p><p>If he is a child, and the injury is less than 3 months old,refer him. If the injury is more than 3 months old, leavehim. Normal movements will usually return in spite of theunsightly hypermobility of his radial head.</p><p>IF REDUCTION OF THE ULNA FAILS so that it remainsseriously angulated, refer him.</p><p>DIFFICULTIES WITH A MONTEGGIA FRACTURE</p><p>If the HEAD OF THE RADIUS WILL NOT REDUCE, it mayhave gone through a hole in the capsule, and so be irre-ducible by closed methods. Open reduction will be neces-sary, so refer the patient immediately. If the dislocation is anold one, reduction may be impossible by any method. If heis an adult, it may then be necessary to excise the head ofhis radius.</p><p>If a Monteggia FRACTURE IS OPEN, do a careful woundtoilet. If there is an haemarthrosis, aspirate the patients el-bow (Fig. 72-4), and reduce the fragments into the best posi-tion you can. Provide skin cover by delayed primary closureor grafting, and then start early active movements.</p><p>73.4 Fractures of the shaft of the radius withdislocation of the lower radioulnarjoint (Galeazzis fracture)</p><p>These are rare, difficult fractures. In children the fracture ofthe radius is greenstick, and the only displacement is an an-terior bow. Adults have a complete fracture of the radius inwhich the distal radial fragment tilts, shifts anteriorly, over-laps, and inclines towards the ulna. At the same time thedistal end of the ulna dislocates from both the radius andthe carpus, and displaces dorsally to make an ugly bulge onthe back of the wrist.Incomplete Galeazzi fractures (children) cause a childs</p><p>lower forearm to bow forwards. He is tender over a green-stick fracture of his radius, usually in its distal third. Thedistal end of his ulna is also tender. Closed reduction is usu-ally straightforward.Complete Galeazzi fractures (adults) are often open,</p><p>with the skin punctured on the front or back of the patientsforearm, and his radius sticking through it. There is usually</p><p>3</p></li><li><p>73 The forearm</p><p>GALEAZZIS FRACTURE</p><p>fragments bowanteriorly</p><p>fragmentsoverlap</p><p>POSTREDUCTIONFILM</p><p>if the ulna isdisplaced distal tothe radius, reductionis unadequate</p><p>Fig. 73.5: GALEAZZI FRACTURES are rare and difficult. In childrenthe fracture of the radius is greenstick, and the only displacement is ananterior bow. Adults have a complete fracture.</p><p>no need to explore the wound because there is no dead tis-sue to remove. Instead, seal the puncture hole with a dress-ing, before you reduce the fracture.</p><p>GALEAZZIS FRACTURE</p><p>INCOMPLETE GALEAZZI FRACTURES</p><p>If the fracture is in the distal third of the radius, evena 45 angulation in a small child does not matter, and sooncorrects itself as he grows. The younger he is, and the closerthe fracture to the epiphysis, the greater the angulation youcan accept.</p><p>If the fracture is higher up in the middle third of thechilds radius, moulding is less rapid and less complete,especially if he is older. So anaesthetize him, and bend hisradius back into place. This reduces the fracture and thedislocation of his distal radioulnar joint. If the distal end ofhis ulna happens also to have been fractured, the overlap ofthe radius usually remains.</p><p>Apply a long arm cast with his elbow at 90, his arm inmidrotation, and his wrist slightly palmar flexed.</p><p>After 6 weeks, replace this cast by a shorter one extendingfrom the upper part of his forearm to above his knuckles.This will hold his radius straight and prevent him dorsiflexinghis wrist. Leave this short cast on for 6 weeks.</p><p>COMPLETE GALEAZZI FRACTURES</p><p>CLOSED REDUCTION Anaesthetize the patient, using a re-laxant if possible. Then suspend his forearm over the side</p><p>AN ISOLATED FRACTUREOF THE RADIUS</p><p>Fig. 73.6: ISOLATED FRACTURES OF THE SHAFT OF THE RA-DIUS. Management depends on the degree of augulation. If angulation isminimal, bandage the childs arm. More than a minimal degree of angu-latinn at the centre of the bone is not acceptable. If necessary, break thebone completely and realign the fragments.</p><p>of the table from a drip pole as in Fig. 73-10.Reduce the fracture until his forearm looks normal, apply</p><p>a long arm cast, and mould it to give it a flat crosssectionas in Fig. 73-9. Complete the cast, and include a ring in it.</p><p>Xray him again, and consult Fig. 73-5. If his radial styloidis distal to his ulnar styloid, reduction is adequate. If his ulnarstyloid is distal, reduction is not adequate.</p><p>If reduction is adequate, continue treatment as for amidshaft fracture of the radius and ulna (73.6).</p><p>If reduction is not adequate, his radius slips anteriorlyinto its displaced position, and his ulna slips distally to thehead of his radius. If possible, refer him within the first weekfor open reduction of his radius. This will correct the positionof his ulna at the same time.</p><p>DISASTER WITH A GALEAZZI FRACTURE</p><p>If the FRACTURE WAS MISSED, both bones will haveunited solidly, and the lower end of the patients ulna willstick out as a lump on the back of his wrist, which will be stiffand painful. Refer him for the excision of the lower end ofhis ulna.</p><p>73.5 Isolated midshaft...</p></li></ul>