Vascularized fibular graft in infected tibial bone loss

Background:

The treatment options of bone loss with infections include bone transport with external fixators, vascularized bone grafts, non-vascularized autogenous grafts and vascularized allografts. The research hypothesis was that the graft length and intact ipsilateral fibula influenced hypertrophy and stress fracture. We retrospectively studied the graft hypertrophy in 15 patients, in whom vascularized fibular graft was done for post-traumatic tibial defects with infection.

Materials and Methods:

15 male patients with mean age 33.7 years (range 18 - 56 years) of post traumatic tibial bone loss were analysed. The mean bony defect was 14.5 cm (range 6.5 – 20 cm). The mean length of the graft was 16.7 cm (range 11.5 – 21 cm). The osteoseptocutaneous flap (bone flap with attached overlying skin flap) from the contralateral side was used in all patients except one. The graft was fixed to the recipient bone at both ends by one or two AO cortical screws, supplemented by a monolateral external fixator. A standard postoperative protocol was followed in all patients. The hypertrophy percentage of the vascularized fibular graft was calculated by a modification of the formula described by El-Gammal. The followup period averaged 46.5 months (range 24 – 164 months). The Pearson correlation coefficient (r) was worked out, to find the relationship between graft length and hypertrophy. The t-test was performed to find out if there was any significant difference in the graft length of those who had a stress fracture and those who did not and to find out whether there was any significant difference in hypertrophy with and without ipsilateral fibula union. The Chi square test was performed to identify whether there was any association between the stress fracture and the fibula union. Given the small sample size we have not used any statistical analysis to determine the relation between the percentage of the graft hypertrophy and stress fracture.

Results:

Graft union occurred in all patients in a mean time of 3.3 months, at both ends. At a minimum followup of 24 months the mean hypertrophy noted was 63.6% (30 – 136%) in the vascularized fibular graft. Ten stress fractures occurred in seven patients. The mean duration of the occurrence of a stress fracture in the graft was 11.1 months (2.5 – 18 months) postoperatively. The highest incidence of stress fractures was when the graft hypertrophy was less than 20%. The incidence of stress fractures reduced significantly after the graft hypertrophy exceeded 20%.

Conclusion:

In most cases hypertrophy of the vascularized fibular graft occurs in response to mechanical loading by protected weight bearing, and the amount of hypertrophy is variable. The presence or absence of an intact fibula has no bearing on the hypertrophy or incidence of stress fracture. The length of the fibular graft has no bearing on the hypertrophy or stress fracture.     

Combining free vascularized fibula graft and the Ilizarov external fixator: recent approaches to congenital pseudarthrosis of the tibia

The present study compares a recent approach for congenital pseudarthrosis of the tibia, combining a free vascularized fibula graft and an Ilizarov external fixator. Between 1984 and 1993, seven vascularized fibula grafts were performed. In the first six cases, casts or unilateral external fixators were applied, and five of these cases were complicated by fractures of the graft, necessitating secondary procedures or long-term immobilization. The mean follow-up was 12.1 years. Five patients can now walk unassisted, and one uses a brace only outdoors. On average, a brace was required for 18 months. In the recent Ilizarov external fixator case, the fixator was removed after 4 months and a brace was unnecessary at 10 months. There was no leg-length discrepancy, severe ankle deformity, or fracture of the grafted fibula 7 years postoperatively. Combining a free vascularized fibula graft with an Ilizarov external fixator is recommended for this condition.     

A roentgenographic, biomechanical, and histological evaluation of vascularized and non-vascularized segmental fibular canine autografts

Advocates of vascularized bone grafts believe that these grafts should have a decreased time to graft-host union, and that they should be mechanically stronger than conventional (non-vascularized) grafts. The objectives of the present study were to determine the rate and pattern of repair in vascularized autogenous cortical bone grafts, to determine the mechanical strength of the grafts, and to correlate the mechanical strength with the biological repair. Forty-nine adult male mongrel dogs were divided into six groups to evaluate conventional (non-vascularized), cuff (periosteal-encased, non-vascularized), and vascularized segmental grafts. The fibula was the site of experimentation and all grafts were four-centimeter cortical segments. The vascularized and conventional grafts were analyzed at two, six, twelve, and twenty-four weeks. The cuff grafts were analyzed at twenty-four weeks and were compared with conventional grafts to assess the effect of the periosteal soft tissue. Roentgenograms were made every two weeks to evaluate the time to union. The mechanical strength of each graft was assessed by determining rapid torsional load to failure. Biological repair was assessed by tetracycline labeling for new-bone formation and by microradiographic techniques for porosity and cross-sectional areas. The study showed that conventional and cuff grafts were similar in terms of mechanical and biological repair at six months. At all sampling intervals, the vascularized grafts exhibited histological findings that were consistent with viability. The conventional and vascularized grafts underwent different mechanisms of repair. The conventional, non-vascularized grafts healed by peripheral and internal resorption followed by callus encasement and osteonal remodeling.(ABSTRACT TRUNCATED AT 250 WORDS)     

Experimental vascularized bone transplantations

The postoperative hypertropy of the vascularized fibula graft is of particular interest. In order to clarify the etiology of the hypertrophy, we conducted experimental projects on vascularized bone grafts using fluorochrome bone labelings, his-tomorphometry and measurement of blood flow in rats and rabbits. In the murine vascularized tibio-fibula graft for bone defects of the tibia, where mechanical stress to the graft can be expected, cross-sectional bone growth was maintained with acceleration of new bone formation and an alteration of growth direction at 3 weeks after the transplantation. In vascularized bone grafts where no mechanical stress to the graft is expected, more bone resorption was seen than bone formation. In the murine tail bone graft to a bony defect of the femur, the cancellous bone gradually disappeared, and the trabeculae took on an architecture characteristic of the femur. This process slowly transforms the graft into a femur with the morphologic features of a long bone. These results suggested that remodeling of the graft corresponding with the changes in the dynamic environment was accompanied by adequate resorption. The cross-age transplantation of vascularized tibio-fibula grafts in rats showed that the younger the donor, the faster the hypertrophy. Age is one of the important factors affecting remodeling of the vascularized bone graft. The blood flow of the grafted bone in the rabbits increased immediately after the transplantation as a reaction to surgery. Thereafter the blood flow of the graft may depend on the biological demands for new bone formation in adapting to the biomechanical environment of the recipient site. © 1995 Wiley-Liss, Inc.     

One-stage treatment of infected bone defects of the tibia with skin loss by free vascularized osteocutaneous grafts

Twenty-six patients who had an infected nonunion or segmental defect of the tibia with skin loss were treated in one stage with debridement and a free vascularized osteocutaneous fibula or iliac graft. Successful control of infection, closure of skin defects, and incorporation of bone union were achieved in all patients except one. In an average follow-up of 39 months, no recurrence of infection was seen. There were four stress fractures of the grafted fibula; these healed within 2 months with cast immobilization. Graft hypertrophy was common in the fibula grafts, but it took 1 1/2 years for hypertrophy of the graft to be strong enough to remove external supports without stress fracture or an additional cancellous bone graft. The use of a one-stage free vascularized osteocutanous graft for the management of infected bone defects of the tibia with skin loss is effective because extensive debridement can remove all devitalized and infected tissue and can increase vascularity in the region of infection and osseous defect to enhance antibiotic delivery. © 1995 Wiley-Liss, Inc.     

Limb reconstruction with vascularized fibular grafts after bone tumor resection

Limb-salvage operations are being used with increasing frequency for patients with malignant bone tumors. For children, when a biologic reconstruction is desired, the choice is often between conventional and vascularized fibular grafts. An experimental study was performed in dogs to compare the two types of fibular grafts for bridging segmental defects in the radius and ulna. Twenty-six adult dogs were divided into two groups and studied at intervals of two, three, four, six, and 12 months after transplantation. The conventional grafts healed by creeping substitution i.e., they were first partially resorbed before new bone was laid down. In contrast, the vascularized fibulae maintained their normal structure and hypertrophied by subperiosteal new bone formation. The conventional fibulae eventually hypertrophied but much later than the vascularized grafts. The vascularized grafts were stronger at four and six months. Between six and 12 months, both grafts remodeled to resemble the size and shape of the forearm bones they were replacing. These experimental results have influenced the treatment of patients. Vascularized fibular grafts are ideal for diaphyseal defects greater than 10 cm long, especially in very young children, a poorly vascularized bed, or when bone healing is delayed by chemotherapeutic agents. To maximize hypertrophy, an external fixator is used to immobilize the graft rather than a plate, which acts as a stress shield.     

Stress fracture of free vascularized bone grafts]

Three cases of stress fracture within free vascularized bone graft were found among 35 patients with completed treatment. In 32 years old male stress fracture of free vascularized fibular graft used for tibial reconstruction occurred after a dozen of one (operated) leg hops. In 29 years old female operated due to tibial pseudoarthrosis with free vascularized iliac wing graft the fracture appeared after couple of days of intense walking. In both cases fracture occurred after incorporation of the graft, several months after removal of the external fixator. Pain and swelling of the limb increased over couple of days. In the last case of 25 years old male vascularized fibula transferred to the femur fractured in the presence of external fixator one year after surgery in the course of remodeling of the graft. In all cases X-ray revealed transverse fracture line in the middle of the graft. Plaster cast immobilization has been used in one case only. Graft remodeling with marked hypertrophy was found 4 month later.     

Die vaskularisierte Knochentransplantation

Vascularized pedicled bone grafts are known since the beginning of the last century. Microvascular bone grafts (free vascularized bone transfer) are known since the beginning of the seventies. In many experimental and clinical studies vascularized bone grafts were compared to their non-vascularized analogues. Because of their own non-interrupted blood supply and thus nearly normal vitality vascularized bone grafts show more rapid fracture healing, more pronounced adaptation to the new mechanical loadings (e. g. graft hypertrophy), higher survival and consolidation rate in poor or bad recipient bed conditions (infection, bad vascularization) and some neovascularization potential on the surrounding tissue. Because of those properties, it became possible to successfully treat a large segmental bone defect by only few operations. As the treatment of complicated combined soft tissue/bone defects led to high complication rate up to 40 to 60% the indications of this method were altered.     

Experimental study and clinical observations on hypertrophy of vascularized bone grafts

In order to understand the mechanisms involved in the hypertrophy of vascularized bone grafts, a series of animal experiments were carried out and 32 clinical cases were studied. A defect in the tibial shaft was created in puppies and the ipsilateral fibula was transferred into the medullary cavity of the tibia with the anterior tibial artery and vein. The same procedure was performed on a control group but without vessel supply. Radiologically, in the vascularized group mild hypertrophy in the fibula was seen at 2 weeks, became marked by 4 weeks, but in no case did the thickening (hypertrophy) of the graft ever exceed the diameter of the recipient tibia. The control group did not show hypertrophy but fracture callus formed in the recipient tibia at both ends of the graft. On histological evaluation no reactive bone formation was evident in the control group but some reactive bone formation was seen in the vascularized group just beneath the periosteum. There was no change in the periosteum itself. In the clinical cases 47% of patients showed hypertrophy. Hypertrophy was noted mainly in the fibulae but rarely in other bones such as ilium or rib. The important factors were age and good vascularity of the grafted bone. During the period of study, weight-bearing was eliminated, so that the effects of mechanical force did not explain hypertrophy. We conclude from these studies that true hypertrophy is an essentially different process from reactive callus which forms normally in response to fracture healing. Vascularized bone grafts show remarkable hypertrophy of the grafted bone, but the exact mechanism is ill defined. In order to investigate the mechanisms, a series of animal experiments were carried out and clinical cases were studied. © 1994 Wiley-Liss, Inc.     

Dynamic external fixation for stabilization of nonunions.

Twenty-five long-bone nonunions were stabilized until healing with a dynamic axial fixator (DAF). Seventeen cases were culture positive and ten had open draining wounds. Five cases had segmental gaps larger than 3 cm. In addition to the DAF, infected atrophic cases received debridement, coverage, and bone graft. Cases with segmental gaps were usually treated with massive posterolateral grafts to create a tibiofibular synostosis. Hypertrophic cases received only compression and weight bearing. Bone grafts were performed in 14 cases. The DAF was usually removed after 16-24 weeks of treatment. Twenty of the twenty-five cases were healed at DAF removal and required no further intervention. Nine of the ten hypertrophic cases healed in an average of 18.1 weeks without graft. Thirteen of 15 atrophic cases were bone grafted. Cases with segmental gaps larger than 3 cm were treated with prolonged external fixation to protect maturing grafts, but were still subject to stress fracture after fixator removal.     

Osteosynthesis of infected and impaired growth of the femur with vascularized fibular graft]

The authors present the causes of difficulties arising during treatment of infected non-unions. Much attention was paid to the unique character of the infection in the thigh and the technical problems related to it. The role of vascularized bone grafts was emphasised. Different possibilities of surgical treatment of bone loss in different localisations were presented basing on clinical material of 7 patients. The authors used various osteosynthesis techniques, most frequently external fixators. Graft healing anf remodelling with different kind of fixators is discussed. The frequency of graft fractures was stressed. The differences in the healing of graft fractures and normal fractures was discussed. The need of suitable elasticity of the external fixator for the correct healing of the transplant and its remodelling was emphasised.     

Experimental study of vascularized bone grafts in rat: Effect of mechanical loading on bone dynamics

We studied the etiology of postoperative hypertrophy of vascularized bone grafts in a murine experimental model. Syngeneic grafting of revascularized ulna to rat tibia was performed with (group 1) or without (group 2) mechanical loading. The effect of simple overloading on intact bone was studied by segmental resection of the radius (group 3). Bone dynamics were examined by histomorphological measurements. Significant hypertrophy was observed in the early postoperative period in both groups 1 and group 2. After the initial phase, bone growth continued and extensive remodeling was observed in group 1, while marked bone resorption was observed in group 2. Adaptive remodeling was also observed in group 3 after surgery, but was slower than that in groups 1 and 2. Early hypertrophy of vascularized grafts did not correspond to mechanical loading. These results suggest that mechanical loading is the principal factor responsible for remodeling in vascularized bone grafts for their adaptation to a new environment.     

Free non-vascularized fibular graft for treatment of large bone defect around the elbow in pediatric patients

Background

Large bone defect is a challenging problem in orthopedics practice. Several methods are available for bridging of these bone defects, including cancellous bone graft, free vascularized fibula graft, and bone transport with external ring fixator. The aim of this study was to describe our experience in nine pediatric cases of free non-vascularized autogenous fibular strut bone graft in which large bone defect and bone loss of >7 cm was caused by open fracture and infective nonunion around the elbow joint.

Objective

To describe our experience in nine pediatric cases of free non-vascularized autogenous fibular strut bone graft in which large bone defect and bone loss of >7 cm was caused by open fracture and infective nonunion around the elbow joint.

Method

This retrospective review was conducted in patients with large bone defect with bony gap >7 cm. Time to union, range of motion, complications, Mayo Elbow Performance Score, and Foot and Ankle Disability Index (FADI) were recorded.

Result

The large bone defects included in this study were managed by free non-vascularized fibular strut bone grafts (FNVFG) that were harvested subperiosteally. Nine patients with a mean age of 11 years (range: 6–17) underwent this procedure. Nine grafts (100%) united at both ends within an average of 9 weeks (range: 8–14). Mean length of defect was 9.3 cm (range: 8–13 cm). Mean postoperative Mayo Elbow Performance Score was significantly higher than the mean preoperative score (98.33 vs. 64.44, respectively; p < 0.001). Three fibulae were observed for hypertrophy. Mean Foot and Ankle Disability Index score was 100 both preoperatively and postoperatively in all patients.

Conclusion

Free non-vascularized fibular graft is a simple procedure and a reliable method for bridging large bone defect or loss caused by open fracture and/or infection around the elbow in pediatric patients.

     

Experimental study of vascularized tibiofibula graft in inbred rats: a preliminary report

An experimental study of vascularized tibiofibula grafts in inbred rats was performed. Roentgenologic and histologic changes of the grafted bone in the first seven postoperative weeks were especially investigated. After preliminary experiments on the vascular anatomy of the lower limbs of rats, tibiofibular vascularized grafts with femoral artery and vein were utilized in Fischer strain F-344 rats. The rate of bony union in the vascularized graft group was superior to that in the nonvascularized control groups. Fluorochrome-labeling studies of the grafted bone at the mid-diaphysis showed active periosteal new bone formation, following the vascularized graft. In contrast, normal tibial bone growth at the mid-diaphysis was mainly endosteal. However, both vascularized graft and normal bone demonstrated evidence of a "drift phenomenon" in the direction of growth. Since the life cycle of the rat is very short, compared with other laboratory animals, this experimental model may be useful in investigating the postoperative course of vascularized bone grafts with a short follow-up period.     

Reconstruction of large posttraumatic skeletal defects of the forearm by vascularized free fibular graft

Vascularized bone graft is most commonly applied for reconstruction of the lower extremity; indications for its use in the reconstruction of the upper extremity have expanded in recent years. Between 1993-2000, 12 patients with segmental bone defects following forearm trauma were managed with vascularized fibular grafts: 6 males and 6 females, aged 39 years on average (range, 16-65 years). The reconstructed site was the radius in 8 patients and the ulna in 4. The length of bone defect ranged from 6-13 cm. In 4 cases, the fibular graft was harvested and used as a vascularized fibula osteoseptocutaneous flap. To achieve fixation of the grafted fibula, plates were used in 10 cases, and screws and Kirschner wires in 2. In the latter 2 cases, an external skeletal fixator was applied to ensure immobilization of the extremity. The follow-up period ranged from 10-93 months. Eleven grafts were successful. The mean period to obtain radiographic bone union was 4.8 months (range, 2.5-8 months). Fibular grafts allow the use of a segment of diaphyseal bone which is structurally similar to the radius and ulna and of sufficient length to reconstruct most skeletal defects of the forearm. The vascularized fibular graft is indicated in patients with intractable nonunions where conventional bone grafting has failed or large bone defects, exceeding 6 cm, are observed in the radius or ulna.     

Histological characteristics of acute rejection in vascularized allografts of bone

Using a genetically defined rat model for the heterotopic transplantation of a vascularized knee in the rat, histological and histochemical studies of acute rejection in vascularized allografts of bone were carried out. The graft consisted of the knee joint with the distal end of the femur, the proximal part of the tibia, the cartilaginous growth plates, the articular cartilage, and a minimum cuff of muscle, which was transferred to a location under the abdominal skin. A total of 160 transplants, including vascularized and non-vascularized isografts, vascularized and non-vascularized allografts that were transplanted across a strong histocompatibility barrier, and vascularized allografts of bone that were transplanted across a weak histocompatibility barrier, were studied by light microscopy at intervals for as long as twelve weeks after transplantation. Vascularized allografts of bone that were transplanted across a strong histocompatibility barrier showed evidence of rapid rejection, similar to that after transplantation of allografts of visceral organs. This was manifested at one week by necrosis of osteocytes, cessation of microcirculatory flow, massive extravasation of red cells, and deposition of fibrin in the marrow. The large vessels demonstrated changes that were characteristic of vascular rejection. Allografts that were transplanted across a weak histocompatibility barrier showed a more gradual, less intense process of rejection that allowed observation of the evolution of the process. In these grafts, the osteoblasts and marrow in the primary spongiosa of the metaphysis were early targets of rejection, as indicated by necrosis of osteoblasts, extravasation of red blood cells, and deposition of fibrin in the marrow spaces. Loss of osteoblasts from the surfaces of osteoid as well as from bone on spicules of calcified cartilage resulted in the cessation of new-bone formation. Calcification of the longitudinal septa between the lowermost hypertrophic chondrocytes was decreased. However, the proliferation and maturation of chondrocytes in the zone of proliferating chondrocytes and in the upper hypertrophic zone continued and resulted in the formation of a thickened growth plate. The loss of osteocytes in other areas of the graft occurred later and only in the areas where the microcirculation had been lost. These data suggest that ischemic damage, which is probably secondary to an immune-related vascular compromise, is a significant factor in the failure of grafts. In the grafts that were transplanted across a weak histocompatibility barrier, the growth of new bone and revascularization by the host occurred by twelve weeks.     

One-bone forearm formation using vascularized fibula graft for massive bone defect of the forearm with infection: case report

Massive long-bone defects of greater than 6 cm are difficult to treat with conventional bone grafts, and other methods are sometimes recommended, such as vascularized bone grafts or bone transport using the Ilizarov external fixator. The combination of local infection with a massive bone defect exacerbates the problem, and provides an even more negative prognosis. The authors treated a large bone defect of the forearm with local infection, using a one-bone forearm formation with a large vascularized fibula graft. They attached an adequate amount of muscle fascia to the vascularized fibula, which was useful not only for coverage of the skin defect, but also for treatment of the local infection. Twenty months after surgery, elbow and hand functions were maintained, and the patient had no disturbance of hand function in daily activities, although rotation of the forearm was sacrificed.     

Treatment of an open distal tibia fracture with segmental bone loss in combination with a closed proximal tibia fracture: a case report

The treatment of open distal tibia fractures remains challenging, particularly when the fracture is infected and involves segmental bone loss. We report the case of a 38-year-old man who sustained an open distal tibiofibular fracture with segmental bone loss and a closed proximal tibial fracture. The fractures were initially fixed with a temporary external fixator. The open distal tibial fracture was infected, and the skin was covered after the wound became culture negative. The tibia was then internally transported with a ring external fixator; the closed fracture of the proximal tibia served as the corticotomy for internal transport without conventional corticotomy. After 5?cm internal transport, the docking site of the distal tibia was fixed with a locking plate and autogenous cancellous bone graft. Bone graft was also used to the distal tibiofibular space to achieve distal tibiofibular synostosis. We describe one treatment option for an infected open fracture of the distal tibia with segmental bone loss that is accompanied by a closed fracture of the proximal tibia. This method can treat two fractures simultaneously.     

The effects of early postoperative radiation on vascularized bone grafts

The effects of early postoperative radiation were assessed in free nonvascularized and free vascularized rib grafts in the canine model. The mandibles of one-half of the dogs were exposed to a cobalt 60 radiation dose of 4080 cGy over a 4-week period, starting 2 weeks postoperatively. The patency of vascularized grafts was confirmed with bone scintigraphy. Histological studies, including ultraviolet microscopy with trifluorochrome labeling, and histomorphometric analyses were performed. Osteocytes persist within the cortex of the vascularized nonradiated grafts to a much greater extent than in nonvascularized, nonradiated grafts. Cortical osteocytes do not persist in either vascularized or nonvascularized grafts subjected to radiation. New bone formation is significantly retarded in radiated grafts compared with nonradiated grafts. Periosteum and endosteum remained viable in the radiated vascularized grafts, producing both bone union and increased bone turnover, neither of which were evident to any significant extent in nonvascularized grafts. Bone union was achieved in vascularized and non-vascularized nonradiated bone. In the radiated group of dogs, union was only seen in the vascularized bone grafts.     

Biological and physical properties of autogenous vascularized fibular grafts in dogs

The biological and biomechanical properties of normal fibulae, fibulae that had had a sham operation, and both vascularized and non-vascularized autogenous grafts were studied in dogs at three months after the operation. The study was designed to quantify and correlate changes in these properties in orthotopic, stably fixed, weight-bearing grafts and to provide a baseline for additional studies of allografts. The grafts were eight centimeters long and internally fixed. The mechanical properties of the grafts were studied by torsional testing. Metabolic turnover of the grafts was evaluated by preoperative labeling of the dogs with 3H-tetracycline for resorption of bone mineral and with 3H-proline for turnover of collagen. Cortical bone area and porosity were measured. Postoperative formation of bone was evaluated by sequential labeling with fluorochrome. The vascularized grafts resembled the fibulae that had had a sham operation and those that had not had an operation with regard to the total number of osteons and the remodeling process, as measured both morphometrically and metabolically. The vascularized grafts were stronger and stiffer than the non-vascularized grafts and were not different from the bones that had had a sham operation. In contrast, the non-vascularized grafts were smaller, weaker, less stiff, and more porotic, had fewer osteons, and demonstrated increased turnover and resorption compared with the vascularized grafts, the bones that had had a sham operation, and the bones that had not been operated on.