Overgrowth Of The Amputation Stump

George T. Aitken, M.D.


Overgrowth of the stump skeleton is a common complication of amputation surgery in children. This report is concerned with a review of our experiences in this area.

We have thirty-nine patients in our child amputee center who have been treated for overgrowth, representing an incidence of 12.4%. These thirty-nine patients are extracted from 308 traumatic (surgical amputations) and six so-called congenital amputations. The group is composed of twenty-eight males and eleven females. The bones involved are the humerus, fibula, tibia and femur. Thirty-two of the patients are Caucasian and seven are Negro. Four had overgrowth which to date has not required surgical conversion. Twenty-seven had a single operative procedure for overgrowth and eight underwent two or more operative procedures, the maximum being three.

Clinically, bony overgrowth of an amputation stump presents itself as a conical extension at the distal end of the stump involved. The bone becomes increasingly pointed and the skin over the area of overgrowth becomes attenuated, thin, unwrinkled and shiny. Occasionally, a bursa develops between the stump skeleton and the skin. In severe cases, there is penetration of the skin by the stump skeleton with the formation of a chronic ulcer and redundant granulation tissue (see Fig. 1A and Fig. 1B ). The diagnosis of this condition is made by clinical inspection and X-ray examination.

Etiology

The etiology of stump overgrowth is not clearly established at the present time. Prior to 1950 there was very little consideration of this problem in the English surgical literature. Most articles simply recognized the complication and indicated that the treatment was revision of the stump. There were, however, a few authors who believed that the condition occurred because of activity of the proximal epiphysis of the involved bone. Epi-physiodesis of the proximal epiphysis of the overgrown bone has been recommended in addition to stump revision. It was suggested that epiphysiodesis would prevent recurrence of this complication.

It is my opinion that overgrowth represents not an epiphyseal contribution, but rather an endosteal or apposi-tional phenomenon.

Fig. 2 -A demonstrates the postsurgical condition of a primary below-knee amputation in a ten-year-old child. At that time metal markers were placed at the distal end of the tibia and fibula. Fig. 2 -B demonstrates an X-ray of the same patient's amputation stump one year later. It is clearly evident that the overgrowth, particularly of the fibula, has taken place distal to the marker, rather than proximal to it.

Figure Three Discussion

Fig. 3A depicts the appearance of a below-knee stump at the age of eighteen months. The etiology of the surgical amputation was a gunshot wound. Fig. 3B pictures the child at two years of age immediately following conversion for overgrowth. Metal markers were placed at the end of the tibial and fibular stumps. Fig. 3C shows the same patient two and one-half years following conversion. Note that the progressive or recurrent overgrowth is distal to the markers. Fig. 3D depicts the same patient at four years ten months of age, following another surgical correction of symptomatic overgrowth with extirpation of the fibula and the placement of a marker in the distal tibia. Fig. 3E shows the same stump two months later. Fig. 3E and Fig. 3F clearly demonstrate that the stump is overgrowing distal to the marker, rather than proximal to it.

Figure Four Discussion

The treatment for the condition is revision of the stump and removal of the bony overgrowth with reclosure of the stump. Many other surgical techniques have been recommended, including surgical synostosis between the overgrown bone and its partner (if the stump is a below-knee or below-elbow amputation). Fig. 4A , Fig. 4B , Fig. 4C , Fig. 4D , Fig. 4E , Fig. 4F , and Fig. 4G represent an example of surgical synostosis in a below-knee stump. At seven years of age (Fig. 4A ), the patient had definite overgrowth of the tibia and fibula, with the fibula overgrowing more than the tibia. At seven and one-half years of age (Fig. 4B ), the stump was revised and a surgical synostosis between the tibia and fibula was accomplishes

At nine years of age (Fig. 4C ), the synostosis was effective, but there was an overgrowing spur in the lateral aspect of the fibula. Between eleven (Fig. 4D ) and thirteen (Fig. 4E ) years of age, the spikes were removed because they were symptomatic but the synostosis was not taken down. At fourteen years of age (Fig. 4F ), another spike had developed and at eighteen years of age (Fig. 4G ), the patient was asymptomatic and the synostosis was complete.

Surgical synostosis appeared to be effective in this case, but it is interesting to note that the patient's tibia drifted into increasing varus following the synostosis. It has not been clearly established why he developed the varus, but it is possible that the inequality of growth of the tibia and fibula at the proximal epiphyses may have contributed to the development of the tibial varus. Whether or not the tibial varus is better than or worse than a recurrence of his overgrowth is questionable. However, because of this and similar experiences we have ceased doing surgical synostoses between the tibia and fibula for fibular overgrowth.

Phenomenon of Overgrowth

Formerly it was the author's opinion that overgrowth as described here did not occur in congenital terminal transverse deficiencies. However, four cases originally diagnosed in this category have demonstrated the phenomenon of overgrowth and are included in this report. In each case we have been unable to obtain a history of some type of surgical intervention prior to the overgrowth. It is therefore hypothecated that so-called congenital terminal transverse deficiencies that demonstrate the phenomenon of bony overgrowth are in reality true intra-uterine amputations. The fact that these develop overgrowth indicates that they are following the pattern of surgical amputations rather than congenital deficiencies.

It is also interesting that there were no vestigial skin remnants of the deficient part in the four so-called congenital cases that demonstrated overgrowth. Fig. 1A and Fig. 1B are examples of one of these cases. This patient was originally classified as an upper hemimelia. The overgrowth has been progressive, but has not required surgical intervention. Since it is behaving as a surgical amputation rather than as a congenital deficiency, it is speculated that this may represent true intra-uterine amputation.

Figure Five Discussion

Fig. 5A , Fig. 5B , Fig. 5C , Fig. 5D , Fig. 5E , and Fig. 5F are X-rays of a patient who was originally classified as a congenital partial hemimelia, lower. At eight years of age (Fig. 5A ), the X-rays demonstrated a spontaneous synostosis with overgrowth; this occurred even though there is no history of surgical intervention and no vestigial remnants of the absent foot. The overgrowth was treated by stump revision at the age of eight years. Fig. 5B demonstrates the appearance of the stump approximately one year post-revision. Fig. 5C is two years post-revision, and there is suggestion of overgrowth of the fibula. Fig. 5D is an X-ray of the below-knee stump three years post-surgical revision with increasing fibular overgrowth.

Fig. 5E and Fig. 5F demonstrate the stump six and one-half years post-revision and in both of these there is definite evidence of fibular overgrowth. This case represents overgrowth in an originally diagnosed congenital terminal transverse deficiency, treated by revision of the stump. There has been recurrence of the overgrowth as demonstrated by X-ray, but symptomatic-ally the second overgrowth has not required surgical revision.

Overgrowth as described here is probably related to longitudinal bone growth but is not specifically a manifestation of epiphyseal contribution. It is believed that the presence of metal markers has demonstrated that overgrowth does take place distal to the marker rather than proximal to it. Experience has demonstrated, however, that this phenomenon does not exist in amputees whose epiphyses have physiologically closed. It may be deduced, therefore, that this appositional bone growth is an inherent characteristic of growing bone.

Summary

In summary, bony overgrowth is a complication of amputations in patients whose epiphyseal lines are still open. In this series, it appeared most frequently in the humerus, fibula, tibia and femur, in that order. This phenomenon was observed in four cases that were originally classified as congenital terminal transverse deficiencies without any surgical intervention prior to the overgrowth. It is hypothecated that overgrowth in these so-called congenital amputees may be an indication that the congenital deficiency was a true intra-uterine amputation. Implantation of metal markers at the time of revision of these stumps has demonstrated that overgrowth takes place distal to the marker rather than proximally. Epiphysiodesis of the proximal epiphysis in the overgrowing bone is not recommended as treatment. Revision of the stump with removal of the overgrowth is the recommended procedure.

George Aitken is Medical Co-Director, The Area Child Amputee Center Michigan Crippled Children Commission, Grand Rapids, Michigan