(6) Traumatic popliteal aneurism.—Wounded at Modder River. Entry (Mauser), over centre of tibia 1 inch above the tubercle. Exit, about centre of popliteal space. No hæmorrhage of any importance occurred from the wound, but there was a typical hæmarthrosis, which subsided slowly. Twelve days after the injury a pulsating swelling the size of a hen's egg, to which attention was drawn on account of pain, was noted in popliteal space. The pulsation extended upwards in the line of the artery some 3 inches. The limb was placed on a splint and treated by rest, and a month later the aneurism had decreased to one half its former size, the wall having greatly increased in firmness. Pulsation was easily controlled by pressure above the tumour; there was no thrill present, but a high-pitched bellows murmur. The patient was sent home on February 1.
When admitted at Netley the patient came under the care of Major Dick, R.A.M.C., who ligatured the popliteal artery on the proximal side by an incision in the line of the tendon of the adductor magnus. The aneurism then consolidated.
(7) Traumatic popliteal aneurism.—Wounded at Magersfontein. Entry (Mauser), centre of patella. Exit, centre of popliteal space; the knee was bent at the time it was struck. There was considerable primary external hæmorrhage, and so much blood collected in the knee-joint that it was aspirated. On the eighth day secondary hæmorrhage occurred from the exit wound and the femoral artery was tied in Hunter's canal. No further hæmorrhage occurred, but at the end of three weeks feeble pulsation was palpable in the popliteal space, suggesting an aneurism; the latter decreased and the patient was sent home apparently well.
(8) Traumatic axillary aneurism.—Wounded at Karree. The bullet entered 2½ inches below the acromial end of the right clavicle and emerged over the 9th rib in the posterior axillary line. The Mauser bullet was found in the patient's haversack. Both apertures were of the slit form, and healed per primam. Three weeks later at Wynberg a large arterial hæmatoma which pulsated was noted in the axilla. Signs of injury to the musculo-spiral nerve were also observed. The tumour altered little, but a fortnight later Major Burton, R.A.M.C., cut down upon it through the pectorals. The aneurism was of the third part of the axillary artery, and a ligature was applied at the lower margin of the pectoralis minor. The wound healed by primary union and the aneurism rapidly shrank. The patient left for England a month later; the musculo-spiral paralysis was improving. I am indebted to Major Burton for the notes of this case.
(9) Traumatic popliteal aneurism.—Wounded in Natal. Entry (Mauser), immediately above head of fibula. Exit, immediately inside semi-tendinosus tendon at level of central popliteal crease. Fulness but no pulsation was noted at end of three weeks; seven days later pulsation was evident, and an aneurism the size of a pigeon's egg, with firm walls, became localised and palpable. It gave rise to no symptoms, and patient refused operation during the three weeks he remained in hospital. The aneurism continued to contract, and the patient was sent home. The aneurism has since spontaneously consolidated.
Aneurismal varix and varicose (arterio-venous) aneurism.—Uncomplicated cases of aneurismal varix, as might be expected, were less common than those in which the arterio-venous communication was accompanied by the formation of a traumatic sac. The initial lesion accountable for each condition was, however, probably identical, and dependent on the passage of a bullet of small calibre across the line of large parallel arteries and veins. Thus, obliquely coursing antero-posterior wounds of the neck produced carotid and jugular varices; vertically coursing tracks laid the subclavian vessels in communication; antero-posterior tracks the brachial, popliteal, and lower part of the femoral; and transverse tracks, the vessels of the calf and forearm. Given an arterial wound, the mode of development of the aneurismal sac in no way differs from that of the ordinary traumatic variety; the main point of interest, therefore, is to seek an explanation of the causes which may restrict the ultimate result to the formation of a pure aneurismal varix. The explanation is possibly to be found in some of the following circumstances.
Size, position, and symmetry of the vascular wound.—It seems scarcely necessary to insist on the calibre of the projectile, since this alone determined the frequency of these conditions, but it must be borne in mind that in the diameter of the bullets, classed as of small calibre during this war, a range of from 6.5-8 mm. existed. In the case of both the Krag-Jörgensen and Mauser, the shape of the bullet also was better adapted to pure perforation of the vessels. I saw no case of arterio-venous communication in which a larger bullet than one of the four types chosen had been responsible for the primary injury, but a difference of 1½ mm. in calibre in the small projectile might well determine the division, the pure and symmetrical perforation of the two vessels, or the giving way of one side, so that they were deeply notched instead of perforated.
Such positive evidence as was afforded by operation as to the exact condition of the vessels in two cases of femoral arterio-venous aneurism was, that in either case a clean perforation existed.
It is improbable that notching of the two vessels can primarily produce a pure varix, although it may result in the formation of an arterio-venous aneurism, especially if the bullet should have passed between the two vessels in such a way as to notch the contiguous sides. It is impossible to say, in any given case, what the result of secondary contraction of a sac produced in this manner may be in the determination of the ultimate relation of the vessels. In many of the cases clinically designated pure varix, the remains of such a sac may still actually persist. In the case also of pure perforation of the vessels, it is difficult to believe that a localised blood cavity has not originally existed. Given complete division of the vessels, as far as my experience went, arterial hæmatoma was the uniform result.
Under these circumstances I am inclined to believe that a symmetrical perforation of both vessels is the most common precursor of either condition; that the pure varix is the rarer and less likely result, and that its formation is dependent mainly on certain anatomical conditions. The most important of these conditions are the proximity and degree of cohesion of the two vessels, the comparative spaciousness or the opposite of the vascular cleft, and the degree of support afforded by surrounding structures.