Knee Disarticulation Following Snakebite in a Young Child

G. Gray Wells, M.D. Eugene Bigelow, M.D. Duane G. Messner, M.D.


The first American to report on knee disarticulation as a definitive level of amputation was Nathan Smith in 1824. He recognized the importance of a long stump and noted that the procedure caused a minimum of trauma to bone and soft tissue3. Following the Civil War, Otis5 reported a large series comparing the mortality rate with that of above-knee amputations. Modifications of the procedure were soon to be described, such as the Gritti-Stokes procedure6. This operation consists of a supracondylar amputation and fitting the denuded cartilage surface of the patella to the end of the femur as an end-bearing surface. In 1935 Callander2 reported a new operation in which he performed a supracondylar amputation and patellectomy. He attached the rectus femoris tendon in the popliteal fossa to act as an end-bearing buffer for the femur. In 1940 Rogers5 reported 23 knee-disarticulation cases. He emphasized the importance of attaching the patella to the anterior aspect of the femur by a dovetail mechanism so as to increase the end-bearing surface area. He also stressed the importance of suturing the hamstring tendons to the patellar tendon in order to preserve muscle function. In 1954 Batch, Spittler, and McFaddin1 were enthusiastic over the results of their 28 knee disarticulations. They emphasized the importance of maintaining most of the collateral circulation about the knee. In 1966 Mazet4 reported a new technique for knee disarticulation. He advocated patellectomy and shaving of the medial and lateral condyles in an attempt to obtain a less bulbous stump.

Case Report

K. W. was two years of age when she sustained a rattlesnake bite on her left lower leg on Oct. 7, 1965. She received local wound and parenteral injection of antiserum within 20 minutes from the time of wounding and was hospitalized in a community hospital in her hometown. Ice packs were applied to the leg and elevation of the extremity was maintained. Over the next few days the extremity developed edema, ecchymosis and blisters One week after injury she was transferred to Children's Hospital in Denver for further care. At the time of admission the patient appeared toxic and her leg appeared gangrenous from the proximal tibia distally ( ). Following appropriate supportive measures, the patient underwent a knee disarticulation. The wound was closed primarily and healed without incident ( and ). The patient's generalized condition improved rapidly. Three weeks postsurgery she was fitted with her first prosthesis.

Discussion

The knee disarticulation has never gained great popularity as a definitive level of amputation. The main objection has been the difficulty in fitting this length and shape of stump with a satisfactory prosthesis. The bulbous stump occupies the space that could be used to contain the knee-control mechanism. Any attempt to place this mechanism distal to the stump results in a cumbersome and cosmetically unappealing extremity. The prosthesis available today uses external knee hinges and lacks control during swing phase.

In spite of these prosthetic difficulties, the knee disarticulation has recognized advantages. The skin that covers the stump is accustomed to withstanding external pressure. In a child who will be end-bearing in a prosthesis and who will spend a great deal of time crawling, this is certainly of some value. The problem of bony overgrowth which often requires stump revisions is eliminated. More important is the fact that the distal femoral epiphysis which provides about 70 per cent of growth in the femur is preserved. The long stump will provide better balance and proprioception and should lessen the likelihood that hip-flexion contractures will develop.

Prosthetic Fittings

The patient described in the case history was initially fitted with a quadrilateral, total-contact, suction socket, a constant-friction knee, and a SACH foot ( ). She required frequent adjustments to her prosthesis and even developed an allergic reaction to the shellac lining of her socket. She has been changed to a standard knee-disarticulation prosthesis with a leather thigh lacer, external knee hinges, and a SACH foot ( ). This type of fitting has alleviated many prosthetic problems and her gait has steadily improved. Her end-bearing stump stays well healed and her femur lengths remain equal.

Summary

Ideal amputation levels in children cannot be rigidly defined. Epitheses and as much length as possible should be preserved. If a below-knee level cannot be obtained, a knee disarticulation is preferred over a supracondylar level. This amputation preserves the distal femoral epiphysis and provides a good end-bearing stump without the likelihood that bony overgrowth will occur. The difficulty of fitting a knee-disarticulation stump with a quadrilateral socket with resulting disparity in knee-joint levels has been emphasized in this case. It is the feeling at this Clinic that when this patient becomes a teen-ager we will be able to fit her with a quadrilateral suction socket, thereby eliminating the poor cosmesis of the standard knee-disarticulation prosthesis.

Regional Amputee Center Children's Hospital Denver, Colorado

References:
Batch, Joseph W., August W. Spittler, and James G. McFaddin, Advantages of the knee disarticulations over amputations through the thigh J. Bone and Joint Surg., 36-A:921-930, October 1954.
Callander, C Lattimer, A new amputation in the lower third of the thigh. J Amer. Med. Assn., 105:22:1746-1753, November 1935.
Cleveland, Mather, and Oliver S. Hayward, Nathan Smith (1762-1829) on amputations. J. Bone and Joint Surg., 43-A:8:1247-1254, December 1961.
Mazet, Robert, Jr., and Charles A. Hennessy, Knee disarticulation A new technique and a new knee-joint mechanism. J Bone and Joint Surg., 48-A:l:126-139, January 1966
Rogers, S. Perry, Amputation at the knee joint. J. Bone and Joint Surg., 22:973-979, October 1940.
Weale, Felix A , The supracondylar amputation with patellectomy. Brit. J. Surg., 56:589-593, August 1969.