ON

TRANSVERSE FRACTURES OF THE

PATELLA.

BY

JONATHAN HUTCHINSON, F.R.C.S.,

SURGEON TO THE LONDON HOSPITAL.

Received May 17th.-Read June 22nd, 1869.

FOR some years fractures of the patella have claimed my especial attention, on account of certain features which seem to me to have been somewhat misunderstood. I have had large opportunities for examining them, and have done my best to follow up my cases until their final results became known. Some errors have, I think, become current owing to the result being recorded at much too early a date, and more especially has this been the case as regards "bony

union."

On the other hand we are liable to mistakes if we venture to found opinions on museum specimens, to which no life history is attached. My aim has been to connect the circumstances observed in the early stages of these injuries with the conditions discovered in the patient's after-life, or revealed by post-mortem dissection, and thus to get a complete view of the whole case.

With a view to conciseness I have stated my conclusions in a series of propositions. Some of these only express the

general creed of surgeons, whilst others more or less differ from it.

PROP. I. For the purposes of clinical discussion fractures of the patella may be conveniently divided into those in which separation between an upper and lower fragment is possible, and those in which it cannot occur.

PROP. II. The cases in which no separation of a distal and proximal fragment is possible, are much fewer in number than the others, with which they have scarcely any feature in common.

In this group we count cases of vertical fracture (probably very rare); those cases of starred fracture from blows in which no mobility is possible, and in which probably the articular surface of the bone is not involved; and the not infrequent cases in which fragments of greater or less size are broken off from the borders of the bone.

In none of these can any important questions of treatment arise, it being clear that the limb should be kept at rest, and probable that in many instances bony union will result.

PROP. III. The cases in which separation between the upper and lower fragments is possible, are common, and occur especially in adults who follow laborious occupations.

PROP. IV. The line of fracture is usually transverse or nearly so, and often near the middle. If one fragment be larger than the other, it will probably be the upper one. Sometimes the lower one is very small. In a few cases the bone is broken into three or more fragments.

PROP. V. These transverse fractures are not infrequently caused by muscular contraction alone.

PROP. VI.-In the numerous cases in which direct violence is applied to the bone at the moment of fracture, there is almost always muscular contraction simultaneously present, and it is impossible to say which takes the chief share in the result.

The patella probably never breaks transversely except when the knee is more or less bent, and the bone balanced as a lever on the condyles of the femur. Sudden and unexpected flexion, or the necessity to prevent such, is more likely to break it than extreme flexion. The position of the fracture may serve roughly to indicate the degree of flexion existing at the time the fracture happened. If the fracture is very low down, probably the knee was but little bent, and thus the greater part of the bone still resting on the condyles. I have met with not a few cases in which, as far as the patient's knowledge went, no violence whatever was received on the bone at the time of fracture. In a majority, however, there is a history of the knee having been struck against something during the fall.

PROP. VII.-If the bone is broken by direct violence at a time when the muscle is not in action, there will be no material separation of the fragments either at the time or subsequently; and the probability is very great that the line of fracture will not be transverse.

Unless the bone be held firmly as a lever by the muscles at the time it receives the blow, there is no reason why the fracture should cross the bone transversely, and the probability is that it would be starred. The fact that most. fractures are transverse is therefore an argument in favour of the current belief that muscular action is a main agent in causing them. The fact that direct violence under such circumstances cannot possibly rupture the strong fibrous structures by which the bone is everywhere surrounded, explains the circumstance that no subsequent separation is likely to occur.

PROP. VIII. The existence of a wide separation proves that the muscle was in vigorous contraction at the time the bone was broken, and also that the fibrous structures have been extensively lacerated.

The fibrous structures at the sides of the patella are especially strong and are firmly united with it. To admit

of wide separation there must necessarily be a considerable laceration into the front of the joint. Such laceration is possible only at the time of the accident.

PROP. IX. In all cases of transverse fracture involving the whole thickness of the bone, the knee-joint is necessarily implicated, and it is probable that blood will find its way into the joint, and that synovitis with effusion will follow.

The quantity of blood in the joint is probably often very small, but in severe cases it may be considerable. In one case under my observation it distended the joint, and it was necessary ultimately to evacuate it by incision. The effusion of synovia is an almost constant result, and is, I believe, a very important complication of the case.

PROP. X.-There is no persistent contraction of the quadriceps extensor, or of any part of it, after transverse fracture with separation. When the spasmodic effort which attended the fracture ceases, the muscle usually remains completely and permanently at rest.

My experience has invariably been to find the front of the thigh soft and flabby, the quadriceps being quite at rest. I have scarcely ever known the muscle pass into spasm during examination, but in reference to this remark I must state that it does not apply to the first few hours after the accident, respecting which my knowledge is very limited.

PROP. XI. The subject of a transverse fracture of the patella is usually quite unable by volition.to put the muscle into action, and there is no reason to believe that the muscle is liable to attacks of accidental spasm.

If you ask a man with a recently broken knee-cap to try to lift his limb from the bed, he will reply helplessly, "I cannot;" if you urge him he will get emphatic and