CHAPTER IX. FRACTURES OF THE LOWER END OF THE HUMERUS. (Part 1)

CHAPTER IX. FRACTURES OF THE LOWER END OF THE HUMERUS. Surgical Anatomy. — The lower end of the humerus articulates with two bones; the types of these articulations are entirely different and the fractures occurring in this region are complex. The lower Fig. 164 (top). Fig. 165. Fig. 166 Fig. 164. — Anterior surface of lower end of right humerus. I.E., internal epicon- dyle; C, capitellum ; T., trochlea. Fig. 165. — Lower end of left Jiumerus seen from below. T., troclilea ; C, capitel- lum; I.E., internal epicondyle ; E.E., external epicondyle. Fig. 166. — Mesial aspect of lower end of left humerus. I.E., internal epicondyle: E.T., edge of trochlea. end of the bone curves forward and is flattened from before back- ward. The articular surfaces may be described roughly as a cylinder mounted on the lower end of the shaft, with the axis of the cylinder nearly transverse to the long axis of the shaft. The outer 120 FRACTURES OF LOWER END OF HUMERUS 121 end of the cylinder is at a slightly higher level than the inner end. When the elbow is fully extended the arm and forearm are not in the same straight line but form an angle of about 170 degrees. The difference between this angle and a straight line is 10 degrees, half of which is caused by the obliquity of the articular surfaces of the Icwer end of the humerus, wliile tlie other half is tlie result of the position of the bones of the forearm. In complete extension, therefore, we have the ''carrying angle" wliile in complete flexion the forearm comes in contact with and folds directly upon the arm. AYhen the fragments, in fractures of the lower end of the humerus. Fig. 167. Fig. 168. Fig. 167. — "Crescentic" fracture of lower end of humerus. Slight lateral displace- ment. Fig. 168. — "Crescentic" fracture of lower end of liumerus with more pronounced lateral displacement. are allowed to unite in deformity there may be a disturbance in the carrying angle which is apparent when the arm is extended, and in addition there may also be a deformity in which the fore- arm does not fold directly against the arm in acute flexion. The carrying angle varies considerably in different individuals and the examination should therefore include comparison with the unin- jured elbow. A certain amount of hyperextension is normal in the elbow, and by means of this position longitudinal stress may be borne by the upper extremity independently of the extensor muscles, tlie action resembling that seen in the knee when the joint is hyperextended. 122 FRACTURES AND DISLOCATIONS The lower end of the humerus is deserving of detailed considera- tion so that the fractures occurring in this portion of the bone may be more thoroughl}- understood. The external condyle (epicondyle) is a small, tubercular eminence situated just above and a little external to the capitellum. It affords attachment to the external lateral ligament and some of the extensor and supinator muscles of the forearm. It is rarely fractured without at least a portion of tlie capitellum being included with the fragment. The capitellum is the rounded eminence occupying the outer part of the articular surface. It articulates with the head of the Fig. Fig. 169. — A^ertical fracture of lower end of humerus separating external condyle from remainder of bone. Fig. 170. — Fracture of the external condyle with lateral displacement of elbow. Fracture of the olecranon present but not discernible from this angle. radius, and is rarely injured except when involved in some of the more common fractures of the external condyle. The radius artic- ulates below with the carpus and above with the capitellum, and in falls on the hand violence is transmitted directly to the capitellum through the radius. This type of violence, however, is much more likely to produce Colle's fracture or a break in the sliaft, neck or head of the radius. The obliquity of the fibres of the interosseous ligament enables the ulna to absorb a portion of the shock when violence is sustained in this way. The capitellum occupies only the front and lower part of the bone. The inner portion of the articular surface is taken up by the FRACTURES OF LOWER END OF HUMERUS 123 trochlea wliicli articulates with the greater sigmoid cavity of tlie ulna. It presents a pronounced groove running from before back- ward which is bounded on either side by prominent ridges, the inner being the most marked and extending to a lower level. The Fig. 172. Fig. 171. — T-fracture of lower end of humerus. Pronounced inward and backward displacement of lower fragments. Fig. 172. — "Crescentic" fracture of lower end of humerus with lateral and back- ward displacement of lower fragment. Fig. 173. — Supracondylar fracture with pronounced inward and back-ward displace- ment of lower fragment. Fig. 174. — 'Same case after reduction. trochlea is slightly spiral so that the posterior end is a little external to the anterior extremity. Just above the anterior end of the trochlea is situated the coronoid fossa which, during flexion of the elbow, receives the process on the ulna of the same name. On the 124 FRACTURES AND DISLOCATIONS posterior aspect of the bone in the same corresponding position is found the olecranon fossa. These two fossae are ordinarily sep- arated by only a thin layer of bone and when the depressions are Fig:. 175. — "Crescen-lic" fracture with backward and rotary displacement. Fis. 176. — Fracture of lower end of humerus with backward and rotary displace- Fig. 177. Fig. 178. Fig. 177. — Fracture of lower end of humerus. Deformity not apparent in antero- posterior view. Fig. 178. — Same case seen laterally. Slight backward displacement of lower frag- ment. well marked the bone may be perforated, forming the supracondylar foramen. These two fossge materially weaken the construction of the lower end of the humerus and are usually entered by transverse FRACTURES OF LOWER END OF HUMERUS 125 fractures in this region, and by vertical fractures involving the articular surfaces. The internal condyle (epitrochlea) is much more prominent and larger than the external condyle, and affords attachment to the internal lateral ligament and some of the pronators and flexors of the forearm. It is more easily broken than the external condyle. Directly behind this process is a groove for the ulnar nerve which is not infrequently injured in fractures of the internal condyle. The manner in which the lower epiphysis of the humerus is ossified is of importance in explaining epiphyseal separations in this region, though the resultant conditions are treated in a manner similar to fractures of the same parts. At birth the epiphysis is entirely cartilaginous and throws no shadow under the X-ray, while the lower end of the diaph^^sis is rounded. (See Fig. 251.) Fig. 17 Fig. 179. — Epiphyseal separation of epitrochlea. Fig. 180. — Lateral view of same case. Before the end of the first year the center for the capitellum makes its appearance. At the sixth year the center for the internal condyle is seen; during the eleventh year the trochlea begins to ossify and the center for the external condyle is first seen during the twelfth year. The outer three centers usually fuse with each other and join the diaphysis during the fifteenth year, before the center for the epitrochlea becomes continuous with either epiphysis or diaphysis. The internal condyle joins the rest of the bone at about the eighteenth year. During the latter part of the develop- ment of the lower end of the humerus the diaphysis is seen to project progressively further into the epiphysis so that it comes nearly to the surface between the centers for the internal epicondyle and trochlea. The order in which these centers join the shaft and the thinning of the epiphysis between the trochlea and internal 126 FRACTURES AND DISLOCATIONS epicondyle account for the relative frequency of epiphyseal sep- arations of the internal epicondjde. The ligaments about the elbow play an important part in pro- duction of fractures. With the elbow partially flexed, abduction or adduction of the forearm produces rotation of the humerus. With the elbow fully extended, however, there is practically no rotary effect on the humerus but instead extreme tension is pro- duced on one of the lateral ligaments. If the forearm is abducted the head of the radius is forced against the capitellum and the internal lateral ligament is placed under tension. If the violence Fig. 181. — Fracture of internal epicondyle. Fig. 182. — Separation of epiphysis of external condyle. Fig. 183. — Separation of epiphysis of internal epicondyle. is sufficient the capitellum is fractured, or the bone supporting it is broken off from the remainder of the lower end of the humerus. Instead of either of these lesions the internal lateral ligament may suffer rupture, or an equivalent fracture of the internal epicondyle or trochlea may take place. When the elbow is extended and the forearm forcibly adducted the reverse mechanism obtains. If the forearm is forcibly extended beyond the normal limita- tions of motion the usual result is either rupture of the ligaments or fracture of the lower end of tlie humerus, with backward dis- placement of the fragment. A much more exceptional fracture is one produced by extreme flexion. The types of fracture occurring in the lower end of the humerus are numerous, and have for the most part been named according FRACTURES OF LOWER END OF HUMERUS 127 to tlie portion of the bone involved. The terminology employed by different authors varies and the result has been rather confusing. The usual fractures occurring in this region are : Fracture of the epicondyle. Fracture of the external condyle including the capitellum. Fracture of the internal condyle including tlie trochlea. Fracture of the epitrochlea. Dia-condylar fracture, the break passing transversely through the condyles. Supra-condylar fracture, the break passing just above the con- dyles. T- or Y-fracture, in which a vertical break divides the lower fragment of a supra- or dia-condylar fracture. Comminuted fracture of the lower end of the humerus, in which the lower end of the bone is so broken up that it is difficult to recognize any particular type of fracture. Fracture limited to the capitellum as a result of violence trans- mitted through the radius in falls on the hand. Epiphyseal separations as described above. It wdll be noted that all of the above fractures, except the last two named, may be described as either ''transverse" or "vertical" or a combination of these two. The supra-condylar and dia- condylar fractures are essentially transverse, while the fractures involving the condyles and traversing the articular surfaces are vertical. The Y- or T-fracture shows both vertical and transverse elements. Nearly all transverse fractures pass through the ole- cranon fossa as do the vertical fractures involving the. articular surfaces. Transverse fractures are usually the result of forced hyper- extension of the elbow, and the lower fragment is almost invariably displaced backward. In the typical transverse fracture the low^er fragment is crescentic, the concavity looking upward. This type of fracture has frequently been mistaken for an epiphyseal sep- aration in spite of the fact that there should be no difficulty in differentiating the two conditions when the X-ray is employed. The upper end of vertical fractures may cross either the internal or external supracondylar ridge, but the lower end of the break is frequently placed so that the trochlea is separated from the capitel- lum. This separatioii of the two articular surfaces on the lower 128 FRACTURES AND DISLOCATIONS end of the humerus allows a flail-like lateral mobility at the elbow which is characteristic of the injury. A rare displacement, some- times seen in transverse fractures, is one first described by Posadas, in which the lower fragment is displaced forward while tlie bones of the forearm are luxated backward. AVhen the condyles are separated from each other by a vertical fracture, one or both of the condyles may be displaced so that the relation of the three bony prominences is disturbed. In the normal elbow the prominence of the olecranon and the two condyles should be about on the same straight line when the elbow is fully extended. The olecranon is a trifle neai-er the inner con- dyle. When the elbow is in a position of acute fl(^xion these three bony prominences should occupy the apices of an equilateral tri- angle. This anatomical relation is of great value both in diagnosis and treatment. The muscles attached to the condyles may exert a displacing action when either of these processes is detached. In vertical fractures the condyles are usually further apart than they should be, and the condyle on the detached fragment may be dis- placed forward, backward, upward or downward. In any fracture in which the lateral stability of the elbow is destroyed the carrying angle is lost as the arm hangs by the side, and if the condition is severe the forearm may diverge to the inner side, producing the familiar "gunstock deformity," or cubitus varus. This deformity may occur with any of the transverse fractures and with the vertical fractures involving the articular surfaces. Immediately following the accident this deformity is due to gravity and to the position occupied by the displaced fragment or fragments. If the frag- ments are not replaced and recurrence of displacement prevented the deformity will become permanent when union takes place. In the rare T-fracture or in extensive comminution of the lower end of the humerus the lateral stability of the joint is most com- pletely broken up since both condyles are separated from the shaft and from each other, and the line of fracture divides the articular surface. This type of fractiire usually results from a fall directly on the flexed or semiflexed elbow. Symptoms. — The symptoms accompanying fractures of the lower end of the humerus vary considerably according to the position of the fracture and the severity of the lesion. Pain. sAvelling, local tenderness, loss of function and deformity are all present though they vary somewhat with the nature of the fracture. The traumatic FRACTURES OF LOWER END OF HUMERUS 129 reaction following fractures of the lower end of the humerus is usualh^ pronounced, and a few days following the accident the region of the elbow" may be covered with blebs containing blood or serum. Ecchymosis usually develops within twelve to twenty- four hours and may be extensive. The loss of function is usually complete following transverse fractures or those which involve the articular surfaces. In isolated fracture of either the epicondyle or epitrochlea the loss of function may be surprisingly slight. The patient will be able to use the elbow to some extent though of course the action of the part is somewhat limited by pain. The symptoms peculiar to the different fractures in this region v;ill be considered in detail. Fig. 184. — Fracture of external epicondyle with upward displacement of fragment. Prominence on external aspect of elbow suggestive; palpation reveals fragment. Joint is intact, there being no involvement of articular surface. Condition rare. Fractures of the epicondyle (fractures in which the joint is not entered and the capitellum remains intact) are extremely rare and the symptoms are not pronounced. Moderate local swelling and tenderness in the region of the external condyle is present. The fragment may remain in position or may be displaced in any direc- tion. When deformity exists the fragment is usuallj^ displaced downward. The detached particle of bone can, as a rule, be directly 130 FRACTURES AND DISLOCATIONS palpated and, if the fractured surfaces can be rubbed together, crepitus will be noted. Crepitus may be difficult to elicit if the fragment is not displaced and the swelling is pronounced. De- tachment of the epicondyle will destro}^ to a greater or less extent, the function of the external lateral ligament and accordingl}^ the . 186. Figs. 185 and 186. — Two views of a fracture of lower end of humerus without the characteristic baclvward clisphicement of Uiwer fragment. Note prominence of external epicondyle which is detached. The .ioint remains intact and hence the absence of de- formity such as seen in Figs. 188 and 189. Fig. 187. — Splitting of lower end of humerus with separation of external condyle. Gun-stock deformity and abnormal lateral mobility. Picture taken a few hours follow- ing accident. lateral stability of the elbow may be somewhat disturbed. A vary- ing degree of abnormal adduction of the elbow is often possible. Fractures of the external condyle (vertical fractures which enter the joint and include the capitellum in the detached fragment) are much more common than fractures of the epicondyle and the FRACTURES OF LOWER END OP HUMERUS 131 symptoms are decidedly more pronounced. Pain is severe, loss of function complete and swelling pronounced. The lateral stability of the elbow is usuall}' completely lost and the joint is flail-like in a transverse direction. Crepitus is, as a rule, recognized as soon as the parts are manipulated. On palpating the condyles the epi- condyle is found detached from the humerus, while the epitrochlea is continuous with the rest of the bone. The forearm is usually supported by the uninjured member and the patient is reluctant to release it for examination. When the arm hangs by the side the helplessness of the member is apparent and the usual "gunstock" deformity is recognized at a glance. The fragment is usually dis- placed downward and may be so rotated that the fractured surfaces are no longer parallel and facing each other (see Fig. 218). Fractures of the internal condyle (vertical fractures entering the joint and separating all, or a portion, of the trochlea from the remainder of the bone) . The symptoms are similar to those alread}^ described in the preceding type except that the inner side of the elbow is the most painful and tender, and the internal condyle is found to be the movable part. Loss of lateral stability is even more pronounced than