Achieving optimal function with a very short transtibial amputation is challenging, for both the patient and the prosthetist. The gain of even a few centimeters can open the door for better prosthetic options. Lengthening of short amputation stumps has become an accepted, though uncommon, treatment for amputees.1-18
Some benefits of creating a longer lever arm are decreased energy expenditure during gait19 and implied emotional and psychological benefits.20 Because of the greater surface area to distribute weight, we would expect a decreased occurrence of skin breakdown. A longer lever arm would also provide improved prosthetic fitting (patellar tendon bearing prostheses using supracondylar suprapatellar [PTB-SCSP] suspension vs. joints and lacer) with decreased cost of fabrication and repairs using simpler components. In addition, it is conceivable that early prosthetic fitting could prevent knee and hip flexion contractures and muscle atrophy and help minimize possible psychological problems.
Although the time invested during this procedure seems insignificant compared with a lifetime of improved function, patient/family frustrations and concerns persist. Their frustrations are caused by a decline in function and independence because of the patient's inability to ambulate and impaired perception of self-image.
A 19-year-old man required multiple amputations in 1994, when he fell near an electrical transformer and grasped it with his left hand. He sustained severe electrical burn injuries to the left hand and to both lower extremities, resulting in amputation of three extremities: 1) a left shoulder disarticulation, 2) a right long transfemoral amputation, and 3) a left short transtibial amputation.
After his first team evaluation at our institution in 1997, he was fit on the right lower extremity with a standard transfemoral prosthesis with a single axis knee joint and a solid ankle, cushion heel (SACH) foot. Because of the lack of tibial length on the left, the patient was fit with a PTB-SCSP transtibial prosthesis with SACH foot, with the possible consideration of joints and lacer. His most recent transtibial prosthesis was fabricated at Shriners hospital and applied in October of 1999. At that time, his fit and function were less than ideal because his residual limb was so short (8 cm) (Fig. 1).
In July of 2000, the team discussed treatment options, including lengthening his very short transtibial limb. The risks of performing the limb-lengthening procedure include nonunion, malunion, intra-articular injury or joint stiffness, and pin tract infections—all problems necessitating lengthy hospitalization and creating an inability to wear the prosthesis for an extended period. The patient agreed to proceed with the limb lengthening via use of an external fixator.
On August 29, 2000, the patient underwent the initial procedure for lengthening. The proximal tibia was divided in a transverse half-barrel cut to ensure that the lengthening took place distal to the insertions of the patellar ligament anteriorly and the hamstring tendons posteriorly.12 A Hoffman external lengthening fixator (Stryker Howmedica Osteonics, Geneva, Switzerland) was applied. This fixator has been our preference in our eight tibial stump lengthenings because of the very small bone fragments involved and the freedom the apparatus gives during the lengthening process for the patient to move the knee (Fig. 2). The Hoffman fixator uses through-and-through pins. This fixator choice contrasts with our use of a small Wagner device (Synthes, Monument, CO) for our 16 femoral lengthenings.12
One week after installing the Hoffman external fixator, lengthening began at the rate of 1 mm/day. Six weeks after surgery (10/12/00), distraction was discontinued because of increased tension of the skin over the distal end of the tibia. The tibia had now been lengthened seven centimeters resulting in a tibial length of 15 centimeters (Figs. 1 and 3). The patient continued to wear the external fixator until the bone consolidation (7 months). At the end of the active lengthening period (6 weeks after surgery), the patient was referred back to the clinic for a temporary transtibial prosthesis modified to fit around the external fixator.
The design and fabrication of the patient's temporary prosthesis were predicated on the distraction fixator selected. In this situation, the Hoffman device had three superior and three inferior pins that protruded from both the medial and lateral sides of the patient's stump. The ends of the pins were connected to a Hoffman distracter both medially and laterally.
During prosthetic fitting, it was our goal to design a temporary socket that prevented distal end contact and to provide relief to both medial and lateral pin sites. Because slot reliefs on each side of the socket were required to enable donning and doffing, it was imperative to fabricate a socket that did not allow for any anterior-posterior expansion.
In phase one, accurate anterior-posterior measurements were vital, along with 1-inch incremental measurements. Plastic cling wrap was draped over the transtibial limb to provide as intimate a cast as possible. Four-inch splints of rigid plaster were used to make an anterior wall template. To capture the contour of the transtibial limb, a 2-inch elastic plaster bandage was wrapped over the rigid plaster and around the pin sites. To assure appropriate pressure along the anterior tibia, it was essential to extend the popliteal wall proximally and apply significant pressure to the patellar tendon at medial tibial plateau. Cast scissors were used to cut the medial and lateral sides to allow removal of the negative cast. In phase two, diagnostic check sockets were fabricated using 12-mm Durr-plex plastic (Fillauer Inc., Chattanooga, TN), The popliteal shelf was modified 18 mm above the medial tibial plateau to emphasize horizontal counter-pressure at the patellar tendon and along the anterior socket wall.10 Although the higher posterior wall did limit knee flexion, primarily while sitting, it was necessary to help prevent any distal end contact. Openings on both medial and lateral sides of the socket provided 12 mm anterior-posterior weight relief to the proximal and distal pin site. Twelve millimeters of clearance inferior to the distal pins was necessary to prevent pin contact against the check socket while weight bearing. Three check sockets were pulled to reach these dimensions.
The definitive socket in phase three was fabricated with extra carbon to increase rigidity and strength. Ratchet buckles were anchored between the superior and inferior pins on each side of the socket, to insure against anterior-posterior socket expansion. No socket liner or padding was used as an interface for fear that blood or drainage from the pin sites would be absorbed by the material and become unsanitary. A hard socket would always be easier to keep clean. Because edema was present on the patient's transtibial limb, it was important to use sock ply fit for total contact. Subsequent volume shrinkage would be expected after some use of the temporary prosthesis.
To don his socket, our patient was instructed to pull a 6-inch stockinet completely over the entire leg lengthening apparatus. With his right arm, he was able to slide the socket on; holes were made through the stockinet to allow fastening of the ratchet buckles.
The temporary prosthesis had an adjustable pylon and SACH foot. With few alternatives for suspension, a PTB cuff along with a waist belt and fork strap were attached to the temporary prosthesis (Fig. 4). To emphasize weight bearing onto the anterior wall surface, our patient's socket had an additional 3° to 5° of socket flexion beyond standard bench alignment.
As a bilateral lower extremity amputee and having left shoulder disarticulation, it was very difficult for the patient to pull himself to stand. When he began gait training in the parallel bars, slight alignment adjustments were necessary on the transfemoral prosthesis to provide a wider base of support. Upon initial weight bearing, the patient complained of pain along his pin site region. It had been 8 weeks since our patient last walked, and he was very motivated to begin ambulating. With only one sound arm, it was very difficult for the patient to limit his transfer weight bearing onto the temporary prosthesis. Once he was upright, he primarily leaned onto the right transfemoral side. It was vital that the alignment of this transfemoral prosthesis be very stable to provide the security he needed. Gradually, he increased the amount of time and weight transferred onto the lengthened limb. After 1 day of therapy, he progressed outside the parallel bars and was able to walk using an axillary crutch.
To ensure that there was no distal contact, we would frequently ask the patient whether he felt any distal end contact. We also placed a small silicone ball in the socket, in an effort to determine whether he was compressing it. The silicone ball was slightly compressed, indicating approximately 6 mm of distal end relief.
While in physical therapy, the patient's confidence increased as he experienced decreased pain and discomfort. He thoroughly enjoyed his opportunity to stand and walk on his temporary prosthesis. As he continued to practice he became more confident and stable, increasing both endurance and strength.
Five weeks after terminating the leg-lengthening process, the patient was ready for discharge from Shriners Hospital on his temporary left transtibial prosthesis. He was scheduled to return in 1 month to evaluate bone condensation and decide when to remove his leg-lengthening fixator.
When the patient returned 1 month later, he stated that he used the temporary prosthesis on a daily basis and was now ambulating without any assistive device. He was wearing approximately a two-ply fit but stated that after prolonged use, his stump would occasionally swell, preventing further usage that day. On evaluation of the radiographs, the orthopedic surgeon felt that the bone consolidation was significant but recommended that the patient continue wearing the external fixator for 1 month longer. When the patient's radiographs were examined the following month, the orthopedic surgeon decided the bone had consolidated sufficiently to schedule removal of the external fixator.
With a residual limb now measuring 15 centimeters, the CAPP physician prescribed a standard PTB prosthesis with a patellar cuff and SACH foot. Upon completion of the definitive prosthesis, the patient stated that he felt a greater degree of control over his new socket fit.
There were few if any adjustments necessary in transitioning the patient from the temporary prosthesis onto the definitive prosthesis. Some small blisters did develop over the newly scarred tissue around the pin tracts. They were treated with topical medications and dressing changes.
Nearly 2 weeks after admission for removal of his external fixator and fabrication of a new definitive prosthesis, the patient was ready for his final discharge from Shriners, having completed the entire lengthening process of his onceshort left transtibial limb.
Early prosthetic fitting during the consolidation phase of the lengthening procedure has many potential benefits. We observed many of these benefits in the patients who were fit with a transfemoral temporary prosthesis over the Wagner lengthening device.8-12,19-21 The small Wagner device is a lateral fixator with pins protruding on the lateral side only; this made fabrication of a transfemoral temporary prosthesis easier.21
Although some benefits are probably achieved, they have not been empirically measured. Research referring to amputees and energy consumption is currently based on levels of amputation (Symes, transtibial, knee disarticulation, transfemoral, hip disarticulation).16 Yet little or no research has been done to relate the length segment of amputation level (8 cm vs. 16 cm transtibial) and energy consumption. We believe that additional length in transtibial amputations allows for a lower consumption of energy, along with a more efficient gait using a simpler prosthesis (joints and corset vs. PTB-SCSP).17 The patient also expressed a greater degree of control of his transtibial prosthesis.
We believe patients may also experience implied psychological benefits from the decreased time without a prosthesis. The ability to maintain some function and independence using a temporary prosthesis similar to their definitive prosthesis may provide added incentive to undergo this procedure. In this case, the patient was fit immediately after discontinuation of the distraction process. Fitting him promptly with a temporary prosthesis decreased the time the patient spent without a prosthesis to only 2 months, instead of the 7 to 15 months that has been reported in other case reports, reducing the time without a prosthesis by 65%. By using a temporary prosthesis during his rehabilitation process, the patient regained his independence earlier and retained more function during the lengthening process.
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