Early Opinions Concerning The Importance Of Bony Fixation Of The Heel Pad To The Tibia In The Juvenile Amputee

Newton C. Mc Collough, M.D. Joseph G. Matthews, M.D. Ardis Traut, R.P.T. Jack Caldwell, CP.


We have collected data on a series of 38 cases of paraxial hemimelia, fibular or tibial (primarily the former). Twenty-four of these patients were operated on by other surgeons, who typically performed a below-knee amputation (14 unilateral, four bilateral), usually at the site of the dimple. The six remaining children had been surgically converted to knee-disarticulation amputees. In these latter cases the surgeons apparently felt at the time of operation that the tibial kyphosis presented an insurmountable prosthetic difficulty to a successful below-knee fitting. In the light of modern prosthetic knowledge, this assumption is no longer true. Even though a child has a short tibia and a small calf, the tibial kyphosis does not present any fitting problem whatsoever, unless it is extremely marked, which is unusual.

Nevertheless, the question still remains as to whether below-knee amputation is the optimal method of treating these children. Some of the cases we have seen were amputated at the below-knee level at a very young age. One, initially operated on at the age of six months, has since had six revisions for bony overgrowth in which the tibia actually protruded through the skin with subsequent infection. This stump is now so short that we are having great difficulty in fitting the patient as a below-knee amputee. The maintenance of maximum stump length by retaining the distal tibial epiphysis is of paramount importance. The rule that the closer the length of the stump approximates that of the lower extremity prosthesis, the better the gait, should never be ignored.

The 14 children who have come directly under our care were managed conservatively In the past, usually without amputation and with the use of non-standard prosthetic appliances. More recently we have begun to apply the surgical technique to be described In this article.

Occurrence of Heel Pad Migration

Two of the 38 cases had a modified Syme amputation of the foot, with surgical removal of the heel pad from the os calcis and re-application over the articular surface of the tibia. In both cases heel pad migration occurred. The first patient underwent the surgical procedure at the age of four years in February 1961, and the heel pad migration was first noted in March 1963, approximately two years and one month later. The second case was treated in a similar manner at the age of seven years, with the heel pad applied in the same manner. However, the pad had migrated so far posteriorly by the time the boy reached teen-age that it was useless as an end-bearing organ. Multiple revisions were necessary because of bony overgrowth.

It is our feeling that when an operation of this type is performed at an early age, as was done with these two patients, the heel pad, scar and neuromata migrate either posteriorly or anteriorly with growth, and the end-bearing potential of the heel pad is completely lost. As the heel pad migrates into a nonfunctioning position, it atrophies markedly and becomes almost unidentifiable. When asked where his heel is, the patient frequently points to a small dimple, appearing as an irregular change in texture of the skin, on the posterior or anterior aspect of the leg.

It is our observation that, in a child, the heel pad cannot be surgically preserved in the proper position to serve as a weight-bearing entity unless the pad retains its original attachment to the plantar surface of the os calcis, which is then arthrodesed to the articular surface of the tibia. The heel pad cannot be surgically removed from the inferior (plantar) surface of the tuberosity of the os calcis without breaking up the fascial cells of the pad, which are similar to a honeycomb, at their superior surface. This destruction considerably decreases the ability of the pad to withstand pressure and, frequently, the function is never regained. Firm re-attachment of the pad to the bone does not occur or does so for only a brief period of time. Failure to unite is the common outcome when the detached heel pad is approximated to the articular surface of the distal tibia. This unfortunate event can be avoided if a portion of the os calcis is used to preserve a firm bony anchorage to the tibia.

Comments of Boyd

This type of surgical procedure does not represent a new development. Boyd1 applied a similar technique in the case of an adult patient whose forefoot had been crushed by a train. He concluded that, "For the patient who cannot afford an artificial leg, or for the laborer, the amputation with calcaneo-tibial arthrodesis, as described, gives an excellent weight-bearing stump and relieves the patient of the inconvenience incident to the use of an artificial limb. The operation is more advantageous, both from an anatomical and from a physiological standpoint than other amputations through the region of the ankle or the tarsus."2 Boyd also cites a reference in the literature indicating that an almost identical operation had been performed in 1907 for "long-standing talipes equinus due to infantile paralysis".3

As far as we know, however, the application of the procedure in the surgical correction of paraxial hemimelia fibular has been limited. We have performed an operation of this type in the three cases described in this article, bet only two of these had paraxial hemimelia fibular. Kruger4 has reported one or two cases of this type, and we have been advised that he is considering the performance of another in the near future. Since the opportunity to perform this operation occurs infrequently, the combined efforts of surgeons participating in the Child Amputee Research Program and other interested parties are necessary if we are to secure an adequate evaluation of this approach.

Specific Aspects

Since the basic Boyd operation is described comprehensively elsewhere (e.g., Atlas of Amputations,5 and standard references) , we will restrict our comments here to certain specific aspects of the procedure.

The talus, if it is present, can be removed and the os calcis can be cut in a parallel plane, so that only a fragment remains, with the heel pad firmly attached. Since the loss of vertical height in the hind foot relieves soft tissue tensions, no difficulty is experienced in positioning the fragment to the distal tibial epiphysis, which has been denuded of cartilage. The fragment is then firmly attached with two or three oblique Kirschner wires until bony union is achieved. The forefoot itself may or may not be removed in the initial stages, depending upon the wishes of the patient and the family.

Support for the satisfactoriness of the fusion procedure is supplied by Hatt,6 who has reported that a series of fusions of the talus to the distal tibial epiphysis were performed without disturbing its growth. We recently reviewed a series of long-term cases of this type and concluded that Hatt was correct. Chuinard7 has also reported a method of achieving arthrodesis of the ankle without transgressing the epiphyseal line or arresting growth.

In the many instances where the femur is short, the patient can be fitted with an end-bearing above-knee prosthesis, either with or without arthrodesis of the knee. Even at this level the value of the heel pad as a means of providing full end-bearing should not be overlooked. Prolonged end-bearing contributes to axial growth in both the tibia and the femur during a child's period of rapid development. Another significant factor favoring this surgical method is that firm fixation of the os calcis to the tibia by bony ankylosis prevents scar migration and bursa formation. It also prevents many of the other complications that develop when an amputation is performed between or at the joints.

Three Case Histories

The first patient for whom we fixed the os calcis to the tibia was operated on at the age of six years. He was a terminal paraxial hemimelia fibular with the foot in marked valgus and with the os calcis rotated almost 90° in the direction of the valgus. He was a very active youngster, but was maintained in a nonstandard prosthesis until October, 1963. At that time, in spite of an attempt to hold him in his socket, increasing deformity (rotation of the os calcis) made surgical interference necessary. The talus was removed and the os calcis was partially rotated under the tibia and fixed in this position. Complete rotation was considered undesirable at that time because of the danger of interference to the circulation of the foot. In May 1964, the os calcis was osteotomized to the point where it could be shifted completely under the tibia and was fixed with two Kirschner wires.

A mid-tarsal amputation was then performed. The patient obtained arthrodesis of the os calcis to the tibia with the heel pad in good alignment to the floor. He is completely free of pain either with or without his Syme-type prosthesis. The lad has marked shortening of the femur and when full axial growth is attained, we believe that fitting as an above-knee amputee will not present any problems, with or without arthrodesis of the knee. (Fig. 1A and 1B , Fig. 1C and 1D , Fig. 1E and 1F , and Fig. 1G and 1H depict this patient both pre- and postoperatively.)

Our second case was a 19-year-old male. He elected amputation because of a severe club foot deformity secondary to a spina bifida, with a deep chronic ulcer over the head of the fifth metatarsal, which was his weight-bearing area. A thin sliver of os calcis to which the heel pad was attached was affixed to the end of the tibia with two wires. The fragment of os calcis united with the tibia and the patient now has an excellent end-bearing stump, which is painless with or without the prosthesis. There is no motion of the heel pad over the end of the stump and it has the appearance of a normal heel structure. This older patient is discussed here primarily because of the paucity of cases to whom this type of surgery has been applied in our clinic to date. The basic tenets of the operation are the same, whether the patient is an adult or a child. (Fig. 2A , Fig. 2B , and Fig. 2C and 2D depict the stump and prosthesis four months post-operative.)

The third patient in this series was born on June 1, 1958, with a congenital terminal paraxial hemlmelia fibular (left, complete), and congenital shortening of the ipsilateral femur. Three-and-a-half months after birth, the fibrous band on the lateral side of his leg was released. The boy came under our care at the age of 17 months. Our initial prescription was a Symes-like prosthesis which enclosed the entire foot with two vertical bars extending to a knee joint thigh cuff. A genuvalgus force was applied through the two vertical bar uprights.

When the patient was almost three years old, he was fitted with a single lateral bar prosthesis with a large build-up in the shoe and a medial "T" strap encasing the foot. In October, 1962, a year and four months later, it was decided that the boy was ready for his third prosthesis. This unit was composed of a single lateral bar upright, thigh lacer, heavy duty knee hinge, leather foot socket, and large rubber rocker bottom pad.

In May of this year, surgery was performed. A rudimentary talus was dissected out as well as part of the navicular, which also blocked inversion. The upper portion of the os calcis was surgically excised and, without invading the epiphyseal plate, the articular surface of the distal tibia was also excised. This was accomplished through an anterior approach, using a horizontal excision from one side of the ankle joint to the other. The os calcis was then repositioned under the talus and it was speared, utilizing a 7/64th Steinmann pin. We were careful to avoid violating the heel pad with any of the incisions or traumatisation of the distal epiphysis of the tibia. (Fig. 3A and 3B , Fig. 3C , Fig. 3D and 3E , Fig. 3F , Fig. 3G and 3H , and Fig. 3J depict the patient both pre- and post-operatively.)

Three Surgical Procedures

In order to preserve the circulation, as many as three surgical procedures may be necessary to gradually move the heel pad under the tibia in the weight-bearing line. Achievement of the ultimate goal of end-bearing is not as difficult as it may seem for either the surgeon or the patient.

These cases are awkward to fit in the early stages, but as time passes the stump tends to mold itself by shrinkage. If an end bearing prosthesis with maximum cosmesis is desired, particularly in the case of a female patient, bone can be removed from the anterior-posterior, lateral or medial aspects of the stump with an osteotome. This trimming will not conflict with the major goal of a stable, comfortable, end-bearing stump which should endure for the life span of the amputee. The basic physiology of the heel pad is not disrupted by the attempt to provide a more attractive appearance.

Four cases of paraxial hemimelia fibular have been operated on at an early age for removal of the fibrous band as described by Thompson.8 Pereneal tendon and heel cord releases were also provided, either by severance or by lengthening. The foot position is invariably improved, and is maintained by Denis-Browne night splints. Ambulation is achieved with a non-standard prosthetic appliance. As body weight increases, however, it becomes increasingly difficult to maintain the heel in its correct alignment. Tilt recurs; valgus in the case of paraxial hemlmelia, fibular; and varus for paraxial hemlmelia, tibial. This deterioration is attributed to the inability of the non-standard prosthetic socket to withstand the pressures exerted, and maintain alignment. Because of this circumstance, it may be desirable to perform the Boyd-type surgical procedure at an early age, even as young as six years.

Conclusions

In paraxial hemlmelia, fibular, the goal of surgical management is to provide a permanent end-bearing stump suitable for prosthetic fitting.

On the basis of past clinical experience, the below-knee or Syme-type operations, when performed on a young child, are not completely adequate for this purpose.

Although experience in its application has been quite limited to date, the Boyd-type procedure involving arthrodesis of a portion of the os calcis (with heel pad attached) to the distal tibia appears promising.

Further investigation of the Boyd-type procedure is necessary to clearly establish its advantages and disadvantages. The cooperation of the participating clinic chiefs to this end is solicited.

Bibliography

  1. Boyd, H. B., "Amputation of the Foot, with Calcaneo-Tibial Arthrodesis," Journal of Bone and Joint Surgery, Volume 21, Number 4, 1939.

  2. Ibid., page 1000.

  3. Loc. Cit.

  4. Kruger, L. M., Shriners' Hospital for Crippled Children, Springfield, Massachusetts, personal communication, 1964.

  5. "The Boyd Amputation" (An Atlas of Amputations) . St. Louis: 1949, pp. 199-200.

  6. Hatt, R. N., "The Central Bone-Graft in Joint Arthrodesis," Journal of Bone and Joint Surgery, 22: 394-402, April 1940.

  7. Chuinard, E. G. and Peterson, R. E., "Distraction-Compression Bone-Graft Arthrodesis of the Ankle," Journal of Bone and Joint Surgery, 45-A: No. 3, 481-490, April 1963.

  8. Thompson, T. C, Straub, L. R. and Arnold, H. D., "Congenital Absence of the Fibula," Journal of Bone and Joint Surgery (American Volume), Volume 39-A, Number 6, December 1957.

Child Amputee Clinic, Florida Crippled Children's Commission, Orlando, Florida