Preservation Of A Very Short Below-Knee Stump
Leon M. Kruger, M.D.
In the past, considerable material has been written on the topic of selection of amputation level, and charts for elective site of amputation have been published frequently. In recent years, however, there has been an increasing realization among those surgeons dealing with children that site of election as a precise location no longer has meaning. Instead, the surgeon must learn to operate on a philosophy of "save all length possible".
An extension of this philosophy includes the preservation of all epiphyses possible, and specifically, the preservation of joints regardless of the shortness of the stump. This is particularly true with respect to the knee joint, and many devices nave been created in an effort to maintain function in the very short below-knee amputation stump.
The philosophy that a below-knee stump should always be preserved in a small child, regardless of how short it is or how much deformity is involved, is illustrated in the following case history.
Case History of Subject B.K.
Subject B.K. was born on August 16, 1956 and was first seen in the clinic at the age of one year in August, 1957. At that time a diagnosis of lower-extremity hemimelia left and a partial hemimelia right was made. It was noted that the boy had soft tissue nubbins on the stump of the right limb. The knee on this limb was described as having a 45° fixed flexion deformity, and the tibial fragment was so small that it was referred to as a "small bony prominence".
On April 2, 1958, the boy was admitted to the hospital for the removal of the soft tissue masses on his limbs. The right knee was then described as having a 50° flexion deformity (Fig. 1 ) and X-rays revealed what appeared to be a 2 cm. rudimentary proximal tibia (Fig. 2 ). The soft tissue nubbins were removed and an effort was made to release the structures at the knee. However, only about 10° of extension was gained by this surgery (Fig. 3 ). The wounds were allowed to heal, and the boy was measured for stubbies which, in effect, were modified UCB sockets elongated and broadened at the bases with an opening posteriorly on the right limb for the tibial stump to protrude. He was actually fitted with the knee in the flexed position (Fig. 4 ).
Use of Stubbies
In August 1958, the patient was readmitted to the hospital for delivery of these stubbies and training in their use. Three months later, he was found to be doing satisfactorily, and it was felt that the stubbies might be elongated by four inches. This was done, and again he experienced no difficulty in achieving balance and was fully ambulatory. It was decided, therefore, to attempt correction of the right knee deformity by supracondylar osteotomy and then to fit him with articulated prostheses.
The surgery was carried out in January of 1960, and three months later the boy was fitted on the left side with a UCB end bearing socket with side hinges and a SACH foot; and on the right side with a standard be low-knee prosthesis with a thigh corset and a toddler's harness. He could ambulate almost immediately, the only major problem being his failure to utilize the knee joint on the above-knee side, which was certainly not unusual for a bilateral amputee.
Readmission to Hospital
The boy's right knee flexion deformity had recurred to approximately 30° in May 1960, and a subsequent Z-ray, a month later, revealed that spontaneous correction of angulation had occurred at the osteotomy site. His flexion deformity continued to increase in severity, and in October, 1960 it was described as between 50° and 60°, and a year later as 90° (Fig. 5A , Fig. 5B , and Fig. 6 ). He was therefore re-admitted to the hospital, and on October 5, 1961, Z plasty incision was carried out in the popliteal space and all posterior structures divided, including the hamstrings and the posterior capsule of the knee joint. This permitted complete extension of the knee, which was maintained by fixation of the tibial stump to the femur with an intramedullary Kirschner wire. Correction was obtained, but it was necessary to use skin graft to close the wound.
Postoperatively, the wound healed, the wire was removed and the patient was started on physiotherapy, and fitted with a new pair of articulated limbs, using a standard willow socket with a thigh corset and side hinges on the below-knee side, and a modified UCB socket on the left side. He has maintained complete independent ambulation and, except for a brief setback in May 1963, when he fell and sustained a subperiosteal crack of his left femur, has experienced no real problem. His stump has continued to grow through the years of treatment, being two-and-a-half inches (inferior patella to tip) at approximately five years, and three-and-a-half inches at seven years, four months, with well defined development of the proximal tibial epiphyses (Fig. 7 ). (Fig. 8A , Fig. 8B , and Fig. 9 depict the patient wearing his left above-knee and right below-knee prostheses at the age of seven years and nine months. Fully clothed his appearance is essentially normal.)
In summary, then, we have described a case in which a very short, flexed, below-knee stump was preserved with ultimate complete correction of deformity and documented evidence of growth of the tibia to provide a suitable and functional below-knee stump.
Leon Kruger is with Shriners Hospital for Crippled Children Springfield, Massachusetts