| BackgroundFibula is regarded as a degenerate bone of a human in traditional anatomy and orthopaedics, and gravity transferred from knee to ankle is only born by tibia. Fibula and the interosseous membrane between fibula and tibia are only functioned as the starting point of the muscles of the leg, and don't have the weight-load effect. Therefore, resection of the fibular shaft doesn't affect the weight loading of the leg, and neither causes the deformity. But inferior extremity of the fibula must be reserved to maintain the stability of the ankle and prevent talipes valgus. And fibula also performs the only function of supporting tibia in clinics. As an unloading bone of the lower extremity, fibula is not regarded as an object for internal fixation and fibular fractures always need not surgical treatment. Therefore, fibular shaft is always an excellent bone graft material. As the developing of the microsurgical technique, vascularized fibular graft is more and more universal as the material to reconstruct the defects of bones and joints in extremities. Because the effect of fibula is only to stabilize the ankle, domestic and abroad researches focused on the biomechanics of the fibular shaft are absent. It is essential for us to completely understand the biomechanics of the fibula to improve the surgical method of fibular transplantation and to enhance the osseointegration between the fibula and the recipient bone. And it is useful to compare the biomechanics properties between fibula and recipient tibia to understand whether fibula can match perfectly with the recipient tibia in biomechanics. Bone healing in connective site can be improved by bone transplantation with vivo-fibula because fibula is not only a rigid of integument but also has abundant blood supply (two systems of blood supply: periosteum and nutrient artery). Fibula is a long bone and has sufficient length for transplantation, and it also has abundant blood supply, constant anatomy and large caliber of blood-supply vessel and is little harmful for donor site; complex tissue transplantation can be implemented with a vascularised fibular flap graft. Therefore, fibula has been widely used as bone graft in reconstructing large bony defect and is regarded as the best choice to treat bone defect, bone un-union and bone late healing. But for some complex bone fractures and bone defects of special sites, regular fibula transplantation by anastomosing blood vessel is not enough for clinical use. So, it is necessary to expend the use of fibula transplantation to solve the difficult clinical problems of complex bone and joint reconstruction.1 Objectives1.1 To examine the basic biomechanical characteristics of fibula in order to figure out theory evidence for using fibular transplantation to repair and reconstruct bone defect. To prove the fibula'pedestal effect on tibia in clinical use by comparing the biomechanical strength between fibula and tibia.1.2 To expend the use of fibular transplantation with blood supply by using a vascularised fibular osteoseptocutaneous flap to reconstruct combined bone and soft-tissue defects in open-tibial fractures.1.3 To design folded vascularized fibular flap (dividing the shaft of the fibula into two or three struts with preservation of a periosteal blood supply to both or all struts through transverse osteotomy where the periosteum and muscle cuff on the posteromedial aspect of the fibula) to reconstruct the complex bone and joint defects that need several segmental cortical bone to support.1.4 To study the effects of anti-inflammatory, bony support and vivo-bone graft by using free-fibular vascularised osteo-flap in treating osteomyelitis of entire tibial diaphysis.2 Materials and Methods2.1 Sixteen couples of fibula and tibias were donated by patients with above-knee amputation. Eight of them were used to perform axial compression test, in which four output parameters, including the maximum compression strength, stress, stiffness and energy absorbed to failure were defined. On the other eight couples of fibula and tibias, three-point bend test were conducted and the maximum bending strength, moment, stiffness and energy absorbed to failure were measured. The output parameters of fibula were compared with that of tibia using paired-t test.2.2 A fibular osteoseptocutaneous-flap unit, which was vascularised by a single peroneal pedicle, was designed by studying the anatomy of fibula blood supply. Briefly, an elliptical skin incision was carried down to the subcutaneous fascia according to the designed size of the flap. The skin flap was elevated rapidly from the lateral and medial margins toward the posterior crural septum between the soleus and peroneus muscles. The inclusion of the deep fascia helps to avoid accidental injuries to the cutaneous branches that originate from peroneal vessels in the posterior crural septum. Moreover, this approach preserves the superficial peroneal nerve. The skin flap was turned forward so all sizable vessels that were seen in the periphery of the posterior crural septum were identified and traced toward their origin. In general, there were 3–5 sizable cutaneous branches that distributed to the skin flap in the middle crura. After the dissection and evaluation of the vessels leading to the skin flap, the flap was reflected to expose the anterolateral part of the fibula. The peroneus longus and brevis, extensor digitorum longus and extensor hallucis muscles were separated from the fibula to leave a 1–2mm muscle cuff. The anterior tibial neurovascular bundle on the anterolateral part of the fibula was identified and protected in the dissection. Both ends of the fibula were severed with an oscillating saw subperiosteally and at a predetermined length usually 5 cm above the lateral malleolus and 5 cm below the fibular head. The interosseous membrane was incised, and the posterior tibial muscle was divided longitudinally to leave only a minimal muscle cuff. The latter was dissected proximally to the bifurcation with the posterior tibial artery and distally to the flexor hallucis longus muscle where the nutrient branch to the fibula can be identified, and the peroneal vessels were traced upwards to their junction with the posterior tibial artery and vein. Then, the peroneal vessels were mutilated according to the recipient site and the free fibular osteoseptocutaneous flap was wrapped with saline-water gauzes.The free fibular osteoseptocutaneous flap was used to reconstruct combined bone and soft-tissue defects in open-tibial fractures in 28 patients. The skin flap was loosely anchored to the wound edge. The vascularized fibula segments were snugly dowelled into the medullary canal of the proximal and distal tibial fragments, so the grafted fibula was bridged across the gaps of comminuted fractures of the tibia by keeping the tibial bone in good alignment with no loss of length. One or two cortical screws were fixed through the tibia and fibualr graft at both ends for the additional stabilization. The available vascularized fracture fragments were arranged around the grafted fibular shaft according to their original sites. The peroneal artery and one of its venae comitantes were anastomosed to the anterior tibial artery and its vena comitans in an end-to-end fashion under the microscope. A cephalosporin and an aminoglycoside were used postoperatively for 7 days. Thromboembolism prophylaxis included: dextran 40(40mg/ml) 500ml for the first two days and then every other day for one week, clorichromene HCL,30mg/die i.v. for the first two days and then 100mg t.i.d. per os for the following eight days. The circulation of grafted flap was carefully observed for six days and the grafted fibula was further protected with a brace for 8-12 weeks. Limited weight loading and functional exercise could be applied according to the condition of bone fusion between the fibula and the recipient tibia.2.3 To design the free vascularized fibular graft nourished by the single pedicle of peroneal vessels by studying the anatomy of fibula blood supply. Five patients with bone defects of both ulna and radius were treated by this method. Briefly, the anterior dissection was carried out by elevating first the peroneal muscle and then the extensor compartment muscle from the anterior shaft of the fibula, where a thin layer of muscle and periosteum was left on the surface of fibula. In accordance with the lengths of bone defects of both radius and ulna, the optimal position of the transverse astronomies of the fibula war defined distally and proximally. Osteotomies of the fibula were made with a Gigli saw to facilitate further dissection of the peroneal pedicle from the posterior compartment muscle after the interosseous membrane was sharply divided. The free vascualrised fibula had been harvested after peroneal vessel was ligated at both ends. At the middle of free fibula, the periosteum and muscle cuff on the posteromedical aspect of the free fibula were elevated for a short distance using a periosteal elevator, and the peroneal vessels were carefully protected during the completion of the transverse osteotomy using an oscillating saw, so the free vascularised fibula was divided into two segments, 5 cm and 6 cm with single vascular pedicle. The distal strut was rotated and folded through 180 degrees so that it lay parallel to the proximal strut. The folded fibula struts were remained good connection and blood supply by muscle and vessel hinge, which usually lied on the internal aspect of each strut. The folded fibula struts were transferred to the forearm, using the distal segment to reconstruct the ulna and proximal segment for the radius respectively. Skeletal stabilizations were achieved with intramedullary Kirschner wires for both ulna and radius. The grafted fibula struts and receipt bones were kept in correct alignment to preserve forearm function as mush as possible. The peroneal artery and vein were anastomosed to the ulna artery and vein at recipient site, where the anastomoses were all made end-to-end with 9/0 nylon interrupted stitches under the microscope. One patient suffered posttraumatic osteomyelitis and nonunions of the forearm, where the complex bone defects of both the ulna and radius combined with large soft-tissue defect were repaired by a fibular osteoseptocutaneous flap.2.4 Long segmental fibula with blood supply was obtained to cure the 15 patients with osteomyelitis of entire tibial diaphysis. Local perfusion with sensitive antibiotic was carried out by femoral artery for 7 days before operation. Length-wise windowing was done in the entire diaphysis of tibia which suffered osteomyelitis, and inflamed and necrosis tissues in the medullary cavity were completely removed. Then, the site was washed by hydrogen peroxide and saline-water with sensitive antibiotics. The fibula was transplanted into the medullary cavity of tibia by screw fixation. The peroneal artery and vein were anastomosed to the anterior tibial artery and vein at recipient site, where the anastomoses were all made end-to-end with 9/0 nylon interrupted stitches under the microscope.3 Results3.1 In axial compression tests, the maximum compression strength and the energy absorbed to failure of tibia were significantly larger than those of fibula (P<0.001); there was no significant difference in the stiffness between tibia and fibula (P>0.05); however, the stress of fibula was far greater than that of tibia (P<0.001). Under three-point bending scenario, the maximum bending strength, stiffness and energy absorbed to failure of tibia were all significantly higher than those of fibula (P<0.001); but no statistical difference in the bending moment was found between fibula and tibia (P>0.05).3.2 The 28 free fibular osteoseptocutaneous flaps were all survived to reconstruct the combined bone and soft-tissue defects in open-tibial fractures in a one-stage procedure. Artery articulo happened in 3 patients 24-48 hours after operation. The artery was re-checked in time and thrombus was found at the anastomotic stoma. The two arteries were re-anastomosed in situ and one artery was anastomosed by bridging with a vein. At last, the three flaps were all survived completely. Wounds healed primary in 21 patients. And delayed healing happened in 7 patients, but no bacterium was obtained from the secretion of the wound by bacterial culture, and the wound healed 3-6 weeks after operation by changing dressings. The follow-up period in the patients of this study were from 5 months to 7 years, averaged 3.5 years. The sign of bony union was found between the fibula and the tibia by using X-ray examination 1.8 months after operation. Favourable bone union was achieved 3.5-4.5 months after operation. Bone non-union and disunion of bone fracture did not happened in all cases. The longest follow-up period is 7 years and 1 month in one case, and the fibula had become thick by the stimulation of stress force and the bone fusion had been achieved between the broken fragments of the tibia and the transplanted fibula. The leg had good weight-load function. Functional evaluation after operation included weight-load pain, joint range of motion and recovery degree of normal work, and the results were divided into: excellent (above 5 points), good (4 points), normal (3 points) and bad cases (2 points). There are 18 excellent and good cases, 3 normal cases and 2 bad cases in all the patients.3.3 A free folded vascularized fibular graft successfully reconstructed the radius and ulna nonunions in a one-stage procedure, and the average healing period was 2.4 months in 4 cases. No cases had happened with the crispation of the forearm and the laxity of the muscle tendon, and the function of the forearm recovered well without restriction of revolving. In another case, a free fibular osteoseptocutaneous flap with folded fibula struts graft also successfully reconstructed the large osseous defects of ulna and radius combined with soft-tissues defect in a one-stage procedure. And bone fusion happened in both radius and ulna after 4.5 months without recurring of osteomyelitis.3.4 Osteomyelitis of entire tibia was successfully cured by long segmental fibula transplantation with blood supply in 15 cases. The follow-up period was from 1.5 years to 3 years, and bony fusion was achieved between the fibula and recipient tibia average 3.8 years after operation. Osteomyelitis never happened again in all cases.4 Conclusions4.1 The results of the biomechanical tests demonstrate that the compression stiffness, stress and bending moment of fibula are higher than tibia though fibula is more likely to fracture. When fibula is transplanted, it acts as bone filler as well as biological fixation devices.4.2 The free-fibular vascularised osteoseptocutaneous flap grafting is an effective alternative for management of combined bone and soft-tissue defects in open-tibial fractures in one-stage procedure. The grafted fibula offers good fracture stabilization and vascularised bone graft to accelerate bone healing, and the fibular flap can also provide a large piece of mobile skin to cover the soft-tissues defect in the open-tibial fractures. The free osteoseptocutaneous flap also serves as a visible monitor of the adequacy of the circulation of the grafted fibula. Transplanted fibular shaft can become thicker and thicker as the time going on, and the fibula can also act as a biological bone nail to support the tibia suffered comminuted fracture.4.3 A free folded vascularized fibular graft or a free fibular osteoseptocutaneous flap with folded fibula struts graft have great superiority in reconstructing the radius and ulna nonunions or the large osseous defects of ulna and radius combined with soft-tissues defect in a one-stage procedure. The method can avoid multiple procedures of surgery and cripation of forearm, and the function of forearm can be restored.4.4 The long segmental fibular transplantation by anastomosing the blood- supply vessels has the great anti-infection ability because of its abundant blood supply, and the fibula can not only reconstruct the bone defects but also improve the anti-infection ability of the recipient site. Moreover, the fibular flap can fill the dead space formed after removing the focus of infection, and the local blood-supply can be improved and the concentration of antibiotics can be elevated. Therefore, the method is very useful to control the infection, reduces the chance of re-infection, and offers the opportunity for successful bone graft in one-stage procedure. |
PDF Full Text Request