Bone Bridge Transtibial Amputation by an Innovative Technique

Abstract

We present a case report of synostosis after transtibial amputation because of distraction regenerate formation after decortication of the lateral surfaces of the tibia and fibula, sequential compression, and distraction using the Ilizarov apparatus. Its advantage is that there is no need to shorten bone. The establishment of distal tibia-fibula synostosis (Ertl) in patients with transtibial amputation has been advocated to improve function and prosthetic wear. There are a variety of techniques to create a bone block. This case reports the successful use of an innovative technique to establish bone block. A patient with transtibial amputation underwent revision of residual limb by decorticating the lateral aspect of the distal tibia and the medial aspect of the distal fibula and acutely compressing the distal ends of the 2 bones with the Ilizarov apparatus. The distal fibula is then slowly and progressively distracted laterally, and the bone is formed in the space between the distal fibula and tibia, creating synostosis with an increased distal bone cross-sectional surface area for improved function and prosthetic wear. The follow-up period was 24 months. Within 3 months, synostosis was formed, which increased the area of the supporting surface and allowed temporary and then permanent prosthetics. After 24 months, synostosis did not differ from the structure of tibial stump bones.

At present, transtibial amputations are performed mainly using the modified Burgess technique¹ and various modifications of the Ertl operation.² Owing to the frequent damage to the interosseous membrane during surgery, the Burgess technique results in the exclusion of the fibula from the loading process in the prosthesis; excessive mobility in the frontal and sagittal planes, which leads to osteogenesis disorders at its end; irritation of the peroneal nerve; and the occurrence of angular deviation, which complicates prosthetics.³ The Ertl technique involves the creation of an osteoperiosteal tube between the tibia and fibula, which is filled with autogenous bone tissue. Based on this, a bone bridge is formed, which expands the bearing surface area and stabilizes the fibula. Other authors⁴ use a fibula graft on a muscle pedicle, which is placed between the tibia and fibula and fixed with a Kirschner spoke or screw. For the same purpose, autografts from the tibia were used,³ which were fixed with the Ilizarov apparatus. Ertl operation makes it possible to obtain a greater vertical reaction force during fast walking, a large stable platform of distal support, and a less load on the distal end of the stump. These advantages are created by the inclusion of the fibula in the walking process. This bone is crucial for the transfer of weight and kinetic energy in knee joint motion and supports the lateral plateau of the tibia. At the same time, the fibula creates an indispensable point of resistance for the mechanical arch between the tibiae.⁵

The disadvantages of the operation are technical difficulty, the need to remove fixators, and a higher rate of complications. The problems of the Ertl operation include nonunion of cortical bone segment or hypertrophic consolidation of cancellous slurry.⁶ The most serious drawback of all modifications of the Ertl operation is the need to shorten the bone.

The Ertl method is especially effective when the stump length is maximally preserved because it provides a sufficient distal platform and good muscle coverage.⁷ According to Bosse et al⁶ and Baumgartner and Botta,⁸ the greater the length of the preserved fibula, the more stable and stronger the knee extension and flexion become. This allows for easier movement and less energy expenditure. According to Plucknette et al,⁹ 46% of patients after Ertl operation and 22% after Burgess operation return to military service.

Case Presentation

A 22-year-old man sustained a mine blast wound to his left lower limb with tissue destruction. In a military field hospital, he underwent amputation in the lower third of his lower leg. The wound was not sutured. Two weeks later, at the next hospital, secondary stitches were applied. The wound healed. He underwent three courses of physical rehabilitation. The primary prosthesis was made. Prosthetics was complicated by persistent pain in the lower third of the stump.

The patient was admitted to our clinic with a moderately conical amputation stump of the left tibia on the border of the lower and middle third. The tibial crest was protruded under the skin. The muscles of the posterior and lateral groups were preserved, sagged in the dorsal direction. The fibula stump was too mobile in the frontal and sagittal planes. During movement, pain was felt on the outer surface of the stump. On radiographs, the stumps of both bones were at the same level. Osteoporosis was moderate. Medullary canals of the tibia (and fibula) were left open (Figure 1).

Figure 1.

Radiographs of the tibial stump in two projections before surgery.

Surgical Technique

The operation was performed under general anesthesia. The surgical field was treated twice with Betadine solution. Two crossed Kirschner wires were inserted into the proximal metaphysis of the tibia and fibula, taking into account the anatomy of the peroneal nerve, without cutting through the muscles, perpendicular to the axis of the limb. A self-tapping half-pin of diameter 3.5 mm was inserted 4 cm below the spokes in the sagittal plane perpendicular to the planum tibia. The wires and pins were fixed in the ring of the Ilizarov apparatus. A flap incision of the skin, subcutaneous tissue, and fascia was made with the removal of old scars. During hemostasis, the stumps of the tibia and fibula and the space between them were isolated. Three linear incisions of the tibial periosteum were made from the edge of the stump in the proximal direction. Two bone and periosteum flaps, 3 × 0.8 cm in size and 2 mm thick, were formed along the cortical plate on the muscle pedicle with a chisel. Similar pieces were formed on the inner surface of the fibula. The formed bone and periosteum plates were laid on the mother bed. The crest of the tibia was sawn off. After perineural injection of 1% novocaine infusion, the tibial, superficial and deep peroneal, and posterior cutaneous nerves were shortened. The end of the fibula was tightly pressed against the outer surface of the tibia. At a distance of 2 and 3 cm from the end of the stump, perpendicular to the axis of the limb, self-tapping rods of diameter 3.5 mm were inserted into the fibula through the decortication zone, which were fixed in the ring of the Ilizarov apparatus using a fixator attachment. The rings of the Ilizarov apparatus were connected by threaded rods. The fibula stump was compressed to the tibia. Muscle plastic surgery (myodesis) was performed with suturing of the anterior tibialis and calf muscles to the tibial crest through the formed transverse channel. The postoperative wound was sutured, drained, and dressed aseptically. The scheme of the operation is illustrated in Figure 2. After 10 days, lateral distraction was performed with the help of nuts, fixing self-tapping half-pins in the bracket with a threaded shank of 0.25 mm 4 times a day. The distraction was continued for 30 days (40 days after surgery). Then, the appliance was set for fixation for 45 days, after which it was dismantled.

Figure 2.

Illustration showing the operation scheme.

Radiography was performed once every 10 days in the distraction period and once a month in the fixation period. The magnitude of diastasis and the nature of the course of osteogenesis were determined.

Ultrasonography examinations were done on VOLUSON-730 PRO (Austria) using linear and convex transducers at 7.5 MHz. The state and size of the regenerate, character of diastasis, homogeneity of the echogenic substrate, presence of endosteal and periosteal bone formation, and hypoechogenic areas were visually evaluated. The echo density index (PEC unit) was determined in seroscale mode. The intact area of the proximal tibia of a healthy limb was taken as a control. The presence of vessels in the distraction zone and in the surrounding soft tissues was assessed in color Doppler mapping and energy Doppler modes. The distraction regenerate was examined after 10 and 30 days of distraction, 60 days of fixation, and 24 months.

Results

In the radiograph obtained after 10 days, signs of a periosteal reaction in the form of a light cloud-like shadow appeared at the site of bone contact closer to the upper edge of the compression site. After 20 days of distraction (30 days after surgery), the width of the regenerate over the entire diastasis area corresponded to the pace and rhythm of distraction (Figure 3). Cloud-like shadows of medium intensity were visualized over its entire area. By the end of the distraction, a normoplastic regenerate was formed, which evenly filled the interosseous space. After 1 month of fixation, homogeneous shadows of high intensity were detected. By the end of the fixation (85 days after surgery), fusion of the bone trabeculae was observed (Figure 4). A cortical diaphyseal layer was formed along the upper and lower edges of the regenerate.

Figure 3.

Radiographs of the stump in two projections 20 days after surgery.

Figure 4.

Radiographs of the stump in two projections 85 days after surgery.

During the scan after 30 days of distraction, the presence of linear hyperechogenic structures of periosteal reaction in the diastasis area was noted. Areas of osteogenesis with different activity were determined (echo density index from 118 to 146 units). Scanning of the regenerate in duplex and triplex modes 10 days after surgery revealed a large number of vessels in the soft tissues. Vessels with a diameter of 0.10 to 0.15 cm were found in the regenerate. On the 85th day after the operation, a continuous contour of the cortical layer and areas of blood vessels in the middle zone of the regenerate with a diameter of 0.21 to 0.26 cm with peripheral indices PI = 3.37 and PI = 1.2, respectively, were found on all scanned surfaces, indicating the maturity of the distraction regenerate (Figure 5). The cross-sectional area of the tibia before the operation was 4.0 cm² and that of the fibula was 1.3 cm². After removal of the device, the area of the end surface of the stump was 13.2 cm².

Figure 5.

Scan of vessels in the regenerate 85 days after surgery.

Discussion and Conclusions

The presented case shows that bone and periosteum decortication with compression of the fibula to the tibia, followed by dosed distraction to the extent of diastasis and subsequent fixation leads to the formation of a regenerate filling the interosseous space.

The first condition for the development of a reparative regenerate is to ensure the immobility of the tibia using the Ilizarov apparatus.^10-12 The second condition is the maximum preservation of the periosteum and adjacent soft tissues, which are the source of blood supply.¹³ This is achieved by bone and periosteal decortication. Bone plates, which retain connection with the periosteum and soft tissues and receive blood supply from them, are a source of reparative regeneration in the early stages.¹⁴ The process of bone formation begins along the periosteal surface of both bones and is facilitated by the presence of laminae. The fusion is formed because of the formation of fibrous connective tissue and periosteal bone and cartilage callus in the compression zone.¹¹ With the distraction of the fibula, the formed connective tissue bridges are gradually stretched.¹⁵ From the periosteal callus, there is sprouting of blood vessels into the vascular-free cartilage and vascular-poor fibrous tissue. On the basis of fibers of immature fibrous tissue and cartilage, coarse-fiber bone beams are formed on the border of bone sections of the regenerate.^10,15 Owing to high reparative activity by the end of the fixation period (85 days after surgery), a regenerate was formed, tightly holding the bones together. A cortical closure plate sealing the medullary canal was formed along the edge of the file because of endosteal bone formation. This made it possible to perform primary and then permanent prosthetics. Two years later, the synostosis and bone cortical closure plate did not differ from the structure of the tibia stump bones (Figure 6). The medullary canals of the tibia (and fibula) are closed by the bony cortical closure plate.

Figure 6.

Radiographs of the stump in two projections 2 years after surgery.

According to the data of Shevchuk³ and Hobusch⁷ obtained during the study of stump supporting with the help of magnetostrictive sensors, the formed synostosis allows increasing the load on the stump by 60%.

After the operation, the prosthesis quality index—the Locomotor Capabilities Index as part of the Prosthetic Profile of the Amputee Questionnaire (Canada, 1993)—was 56. The patient currently uses the prosthesis without additional means of support. He works as a mechanic. He walks up to 15 km per day.

The discussed case testifies to the usefulness of such operations and the possibility of their use in clinical practice.