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The Classic: Fracture of the Base of the First Metacarpal and a Variation That Has Not yet Been Described

Rolando, Silvio; Meals, Roy, A

Section Editor(s): Meals, Roy A MD, Guest Editor; Harness, Neil G MD, Guest Editor

Clinical Orthopaedics and Related Research: April 2006 - Volume 445 - Issue - p 15-18
doi: 10.1097/01.blo.0000205897.21233.11
SECTION I: SYMPOSIUM: Problem Fractures of the Hand and Wrist
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(This reprinted Classic Article is reprinted with courtesy from Rolando S. Fracture of the base of the first metacarpal and a variation that has not yet been described. 1910. This article originally was used as the Classic in the June 1996 issue of Clinical Orthopaedics and Related Research.)

With the publication of his article Fracture de la base du premier metacarpien, Silvio Rolando became the third Milanese surgeon to have a fracture named after him, a distinction he shares with Monteggia and Galeazzi. Like his colleagues, Rolando was a general surgeon. During a period of 30 years he published papers in Italian and French medical periodicals on a wide variety of surgical conditions. Rolando was a member of the Societe Internationale de Chirurgie.

Leonard F. Peltier, MD, PhD

In a statistic of 1847, Malgaigne considered fractures of the first metacarpal to be the most frequent and the most numerous, more than fractures of the other 4 metacarpals. However, other authors have hardly been of this opinion. Boyer, Delpech, and Chelius have assured us that the most frequent fracture is that of the fifth metacarpal. Simpson and Tower say it is that of the third and fourth, and Hamilton says it is the fractures of the second.

Today, thanks especially to radiographs which permit observation and study of some forms of fractures of the first metacarpal that have originally been unknown, we have come to the conclusion that really the fractures of the thumb metacarpal are the most frequent, agreeing with the opinion of Malgaigne and Bardernheuer.

Among these forms of relatively unknown fractures must be placed that which is named the Bennett's fracture. In 1887, at the Dublin Congress, Bennett presented 9 anatomic specimens related to first metacarpal fractures. Five of these specimens showed the following lesion:

“The fracture passed obliquely across the base of the bone, detaching the greater part of the articular surface and the piece of bone that was resting on this surface was projected toward the palm of the hand. The separated fragment was very large, and the deformity that resulted there-from seemed more a dorsal subluxation of the first meta-carpal.”

This type of fracture was according to Bennett the most common among the first metacarpal fractures. Miles and Struthers described more than 15 Bennett's fractures and share the opinion of this author about the frequency of the described fracture.

In a recent publication that includes 92 fractures of the first metacarpal, Robinson (of Boston) found that 2 of the fractures belonged to the illustrated type of Bennett's fracture, 5 of them compromised the inferior extremity, and 59 were of the type of fractures of the base, dissimilar to those of Bennett, without communication with the trapeziometacarpal joint and were not accompanied by subluxation.

For the past year I have been studying this lesion at the surgical ambulatory section of the Civil Hospital of Jenes where one notices a great number of trauma cases especially among port workers. I thought it was interesting to offer a summary of the results of my observations. These are 12 cases of first metacarpal fractures among which 2 were of the middle third and the others were of the base. The latter comprised 1 simple fracture of the base, 1 type Y fracture that did not penetrate the joint, 5 Bennett fractures, and 3 Y fractures entering the joint. The latter have not yet been described as far as I know and constitute the principal subject of this article.

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ANATOMY AND ETIOLOGY

The first metacarpal shows a body, a distal extremity or head and proximal extremity or base.

The dorsal surface of the first metacarpal is flat and terminates near the base in a rounded off extremity. The palmar surface, covered by muscles of the thenar eminence, is not accessible on the living subject. The body has 2 borders, the radial and the ulnar. On the ulnar side the palpating finger notices first coming proximally from the head a cutting, sharp edge which goes just up to the middle third which falls afterwards in a small cavity and which finishes in a tubercle, rather noticeable and which is found immediately under the trapeziometacarpal ligament. The radial edge, more obtuse and irregular than the 1 that we have just described, ends under the trapeziometacarpal ligament in a small tubercle. The articular surface of the base of the first metacarpal has the shape of a saddle with a concavity dorsal-palmar and a small convexity laterally. The trapezium straddles the saddle. The concavity of the saddle is limited by 2 lips, of which the posterior or dorsal (B) is put almost exactly on the part of the dorsal surface of the metacarpal, while the palmar (A) constitutes a sharper lip which slightly protrudes on the palmar side of the metacarpal surface.

Fig 1

Fig 1

It is easy to understand that the dorsal articular process will present a greater resistance to external trauma than will the palmar process, mainly to those forces that act in the direction of the longitudinal axis of the metacarpal. The effect of this trauma is to make the angle formed by this palmar articular process sharper with the metacarpal palmar surface: from this will result an oblique fracture which will compromise this process, following from a particular point there will radiate out from the center of the articular saddle just up to the palmar surface. It is the mechanism by which one can produce a Bennett's fracture. In this fracture the dorsal articular process and the body of the bone tend to sublux dorsally, but this subluxation can only be incomplete if the ligaments uniting the trapezium to the metacarpal remain intact. Then whenever more intensive or sustained trauma occurs to the long axis of the metacarpal, it can also bring along with it the fracture of the more resistant joint process, that is to say, the dorsal process. In this case what happens is a Y shaped fracture is produced by which the proximal first metacarpal is divided into 3 fragments of which 2 parallel the base, dorsal and palmar respectively, and the other corresponds to the body of the bone.

The palmar articular joint fragment always turns toward the thenar eminence. The dorsal joint fragment on the other hand generally keeps its relationship with the trapezium. The distal diaphyseal fragment can sublux dorsally just like a Bennett's fracture as I noticed in 1 of my observations or not turn away a noticeable extent like in the other 2 observations.

In the 5 fracture cases that I have described, the trauma acts on the base of the first metacarpal. In 3 cases this occurred after a blow with a closed fist with the thumb in adduction and in 2 cases, after a fall to the ground with the thumb folded into the palm of the hand. In the 3 cases of Y fractures, the etiologic factor is represented in 1 case by a blow with a closed fist, very strongly against the head of the adversary with the thumb folded and held into the palm of the hand, in the other 2 cases by a fall on the radial side with the thumb in adduction.

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SYMPTOMATOLOGY

Symptoms vary according to whether fracture occurs with or without dorsal subluxation of the distal fragment, however, there are some common symptoms that can be described.

The person sustaining the trauma feels very strong pain which makes him give up work, the swelling that comes right away is very noticeable. This swelling is exclusively on the dorsal radial side of the metacarpal and the trapezium, the first interosseous space, and the thenar eminence.

When the thumb is hyperextended one notices that the indentation in the anatomic snuff box, the depression which normally is found on the ulnar side of the long extensor tendon of the thumb, disappears and is flattened. The long extensor tendon does not show under the skin when the thumb is extended and abducted. Sometimes active movements of the flexion and extension of the thumb are hardly painful but the movements of abduction and adduction can be painful, especially opposition which is accomplished in the trapeziometacarpal joint. The poor man when asked to grasp an object with his fist, has sharp pain corresponding to the base of the thenar region. He can do light manual labor but any work that requires manual force is impossible.

When one palpates the dorsal surface and the medial margin in fractures without dorsal subluxation one sometimes cannot notice any bony deformity. One notices on the other hand diffuse, very strong pain on the ulnar side corresponding to the tubercle, which is under the trapeziometacarpal joint on the dorsal and radial side immediately underneath the articular ligament.

Pressure on the base of the metacarpal, whether in the lateral direction or in the dorsal-palmar direction is very painful. In general, however, it is possible in comparison with the healthy side to notice that there is an enlargement of the metacarpal base. In taking the distal portion of the first metacarpal and bringing it strongly toward the palm of the hand the proximal edge lifts up and knocks against the palpation digit, provoking a very strong pain in the patient. I have not at all been able to feel crepitus in 2 of the cases I have observed and where the radiograph showed the presence of a Y fracture of the base.

In fractures with mobile fragments, the symptomatology of the fracture is much more evident. It is equal to the 1 already indicated, the Bennett's fracture. That is to say it is characterized by noticeable deformities which are due to the dorsal subluxation of the diaphyseal fragment of the first metacarpal. This subluxation is reduced with ease by the simple pressure on the displaced fragment, and you can notice just a fleeting crepitus, but it is reproduced easily when one stops the pressure.

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DIAGNOSIS

The fractures of the metacarpal base without dislocation are generally not recognized and they are mistaken for trapeziometacarpal sprains. Some of the patients whom I have studied went back to work just a few days after their injury spontaneously or advised by the physicians who took care of them; but they had to stop their work immediately because of the sharp pain felt at the thenar eminence when they held tools or objects in their hand.

The differential diagnosis with an articular sprain is not hard; but we have to keep in mind all the indicated symptoms: dorsal radial swelling of the metacarpal and the thenar eminence, disappearance of the thumb extensor tendon prominence, general pain corresponding to the base, and deformity with an accentuated enlargement of the base.

In any case one must never neglect to make a radiographic investigation, which is not a study of luxury. It is a necessity of major importance in the treatment.

Fractures with dorsal subluxation are often confused with incomplete dislocation of the first metacarpal. Its differential diagnosis is not difficult because the deformity of fractures is easily reduced, but it happens again as soon as one ceases the traction on the thumb while the dislocation once reduced does not come back.

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PROGNOSIS

The prognosis is unfavorable from the functional point of view whenever this fracture (principally when the fragments are mobile and there is noticeable displacement) is left to itself or has not received the appropriate treatment. I had to examine a patient who 3 months before had undergone a Bennett's fracture with a very pronounced displacement of the palmar fragment. This lesion was taken for a sprain and it was cared for with massages. The unfortunate patient who was a dock worker, had to give up his job. He had very strong pain with movements of adduction and opposition of the thumb and said that he could not hold anything in his hand because of the extreme pain he felt at the base of the thenar eminence.

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TREATMENT

One must remember that the thumb possesses a very large freedom of movement necessary to its function; and that when we are talking about intraarticular fractures, even relatively small displacements of fragments will be sufficient to alter this reciprocal motion which represents the gliding trapeziometacarpal joint which will have a pretty serious influence on the function.

It is because of this that for all intraarticular thumb base fractures into the joint, I think it is opportune to immobilize the part in extension with maximum abduction of the thumb. Actually according to what I have seen in radiographic research, abduction is the position that is the most convenient, that most easily leads to a good reduction, and that already has been observed in Bennett's fractures by Miles, Struthers, and Robinson. Ordinarily this immobilization must be maintained for 3 weeks whether they are Bennett's fractures or those in Y with dorsal subluxation of the diaphyseal fragment; there is a considerable tendency for the displacement to recur and the dangers resulting from incomplete treatment are increased. In these cases I have gotten very good results from traction exerted by 2 small bands of diachylon applied on the dorsal and palmar side of the thumb and its metacarpal and maintained during application of a plaster apparatus which includes the thumb and fist. This apparatus has to be taken off around the fourth week to begin the methodical mobilization and massage. With this treatment I have been able in almost all my cases to obtain cures without any unusual or untoward consequences.

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CONCLUSION

Resulting from my observations, I have found that there exists a type of fracture of the base of the first metacarpal that has not yet been described as far as I know. This fracture that I have noticed in 3 cases of 10 of base fractures follows an injury acting along the longitudinal axis of the metacarpal. It has a Y form and cannot be distinguished from a Bennett's fracture without radiographic studies, and like the Bennetts's fracture, it has to have a special kind of treatment.

© 2006 Lippincott Williams & Wilkins, Inc.