Ilizarov method as limb salvage in treatment of massive femoral defect after unsuccessful tumor arthroplasty

Introduction. Surgical management of massive bone defects is very challenging in terms of estimating possibilities of saving the extremity and adequate method that can make it possible. Selection of methods is additionally limited in the presence of infection at site of defect. Case report. The female patient, diagnosed with Ewing sarcoma was treated by segmental bone resection and implantation of Kotz modular tumor endoprosthesis. After 5 years the signs of infection occured and persisted with low grade intensity. After falling, 12 years following implantation, the patient acquired periprosthetic fracture. Then endoprosthesis was removed, all along with surgical debridement of wound and application of the Ilizarov apparatus. The apparatus was applied, osteotomy of callus and the tibia performed with transport of bone segments, untill reconstruction of defect and arthrodesis of the knee was achieved. Conclusion. The Ilizarov apparatus offered us huge possibilities for management of massive bone defects with natural bone which has superior biomechanical characteristics comparing to the implant. The most frequent complication of this method is a prolonged treatment period that demands good patient selection and preparation and wide surgical experience.


Introduction
Ewing sarcoma is a highly malignant tumor.In most cases its origin is in bone tissue (approximately 10% origina-tes from tissues that are surrounding bone) 1 .Population younger than 30 years is usually affected 2 .The fact that almost 25% of this tumor are metastatic at the diagnosis time is one of the biggest problems in succesfull treatment 3 .For a Correspondence to: Aleksandar Radunović, Clinics for Orthopedic Surgery and Traumatology, Military Medical Academy, Crnotravska 17, 11 000 Belgrade, Serbia.E-mail: aradunovic@yahoo.comlong period amputation surgery was the only treatment for this pathology.The first announcement of possible new treatment option was made in 1950 when Buchanan 4 introduced total femur replacement.First results of reconstructive surgery were controversial comparing to amputation, a standard procedure for this pathology at that time 5 .The cardinal reason for this was a high frequency of tumor recidives.
Together with improvement of adjuvant hemiotherapy and advancement in endoprosthesis design limb salvage surgery has been established as standard in this area of orthopedic oncology 6,7 .A spectar of new complications arises comparatively with this procedure with infection and residual bone defects among most frequent ones.
There are few available options for treatment of this complication with its benefits and imperfections.One of those, used with a significant succes is the Ilizarov method.First attempts of external or extrafocal fixation originated from the first half of 19th century and were represented by a work of Malgagnie in 1843 8 .In 1966 Russian physician Ilizarov introduced a new method of reconstruction of defects of long bones based on de novo bone formation between bone selvedges created by osteotomy and their latter graduated distraction.The osteosinthesis process is performed in two manners, by bilocal sinchronized compressive distraction or by alternate distraction compressive osteosinthesis 9 .At the very beggining of external fixation, the Ilizarov major aim was treating of bone infection ensued after fracture 10 .He was first who described the influence of exerted distraction in the processes of osteogenesis and suppresion of tissue inflamation reaction without use of antibiotics.

Case report
At the age of 18 the patient was diagnosed with Ewing sarcoma.The patient was treated surgically by segmental resection of the femur and reconstruction of the distal femur with the Kotz type of modular tumor endoprosthesis.Five years afterwards, the signs of low-grade infection occurred (secretion from wound and local rudiness).This was treated by occasional peroral antibiotic therapy in addition to which infection persists.Twelwe years following implantation, after falling, the patient acquired a periprosthetic fracture of the proximal femur and was referred to our hospital for the first time.After clinical processing was completed, we ascertained periprosthetic fracture and the presence of fistula with low secretion of serous pus content.Laboratory parameters for infection as well as culture results of smear were negative.As there were data about a long history of infection and significant wound secretion earlier, we decided to perform extraction of endoprosthesis and surgical debridement.Intraoperatively, we found a small amount of pus and intraoperative culture was negative.Postoperatively, the leg was immobilized with coxofemoral imobilisation.Antibiotic therapy was administered by the protocol that was apllied at that time and, meanwhile changed a lot.It consisted of the 3rd generation of cefalosporin intravenously for 10 days and continued with peroral antibiotics for 21 day.Afterwards, the patient tried to manage further medical treatment in the Ilizarov Center in the city of Kurgan, Russia, but after some time changed her mind and continued with treating at our Clinic.
Before surgery, new x-ray was obtained and healing of the fracture of the proximal femur was found.Femoral defect was estimated approximately 15 cm (on x-ray) relative shortening, while clinical (absolute) shortening of the leg was about 22 cm.After 6 months without clinical and laboratory signs of infection the Ilizarov apparatus was positioned on the thighs and lower leg, corticotomies of the tibia and fibula performed as well as osteotomy of a callus of the fractured fragment of the proximal femur.Then we started with simultaneous transport of a free femoral fragment and distraction of the lower leg aiming at arthrodesis of the knee.The dinamics of fragment transport and distraction was 0.5 mm per day (Figures 1 and 2).Occasionaly, we noticed cut-in of a K wire through skin and consecutive minimal skin necrosis which was treated by local wound cleaning and healed per secundam.Ankle distraction resulted in contracture, as well as equinus foot deformity, that are frequently reported as complications of this method, so we removed this construction after 6 months.Then we performed Achilles tendon elongation (Hoke) and placed construction for correction of equinus deformity.As fractured femoral fragment transport was finished, with good bone regenerate forming, two hoops were placed on the distal femur and adequate construction of the lower leg in order to aplly compression and achieve arthrodesis of the knee.This was enhanced with patellar autologous bonegrafting.This construction was successful for correcting foot deformity and Achilles tendon elongation, but unsuccessful about knee arthrodesis.After 8 months we estimated that the existing bone quality was not good for a new Ilizarov construction, so we removed the existing one and put immobilisation, that was used for next 2 years.Then, in agreement with the patient, a new construction was positioned, accompanied with osteoplastics with alografts, bone ends refreshing and graduate compression, so we reached arthrodesis in 5 months (Figure 3).After finishing surgical treatment, residual leg shortening was 1.5 cm, the patient walked without using any tool, with no pain in everyday activities.The patient restored the same level of activities as before the failed artrhoplasty.Ankle function was excellent, with submaximal range of movement and no pain (Figure 4).

Discussion
Managing the presented patient, the surgeon was in enviable position and in a great dilemma choosing the therapeutic approach.Amputation was a possible option, with the possibility for quick rehabilitation.As the patient was young, with no complications of primary pathology, and highly motivated for reconstructive surgery, it was decided to use the experience with the Ilizarov technique and attempted to manage the existing defect with bone transport and distraction with final knee arthrodesis.The patient was acquainted with the inevitable long period of treatment, as well as with the possibility of other complications.
Surgical treatment of bone defects following trauma, tumors, infections, failed arthroplasties or congenital anomalies can be performed with different methods: free bone grafts, vascularized fibular grafts, custom made endoprosthesis and arteficial bone substitutes.There are advantages and imperfections of each of these methods regarding defect size that can be managed, percentage of nonunion, mechanical strength, donor site comorbidity and surgeons experiance that is needed [11][12][13][14] .Autologous bone grafts can be used in treating smaller defects.Vascularized fibular grafting is an extremely technically demanding procedure and there are reports of significant incidence of pseudoarthrosis and nonunions.Song et al. 15 , published a study that suggested advantage of bone transport comparing to vascularized fibular graft when it come to functional results.
The Ilizarov metod of osteodistraction is a reliable method for managing defects larger than 8 cm 13 , like the one we had to deal with.The most frequently reported complications of this method are a prolonged period of treatment and pin tract infection [16][17][18] .Some authors suggest intramedulary nailing and bone transport over nail for the reduction of treatment time [19][20][21] .There is a widely accepted opinion that pin tract infection is successfully managed by local wound toilette, antibiotics administration and, eventually correction of needle position 16,17,22,23 .One of the most frequently reported complications of this metod is docking site fracture in 25% of patients 24,25 .
Principal advantage of distraction osteogenesis is the possibility to achieve regeneration of live bone that has the same or closely same strength like former bone, with the possiblity of live tissue to adopt for mechanical loads in future.
Difficulties we dealt with during treatment of the presented patient are the most frequent complications of the Ilizarov method in general.At the planning phase and during the treatment, possibilities that could reduce treatment time were considered, but we thought none of them could successfully be applied in this case.We deem that key factors for the success in such a long treatment are patient cooperability and a good relation between a patient and the doctor.If we take a look on economical side, inital expenses for amputation are much lower, but projected expenses of lifetime prosthetic works are larger 26,27 .

Conclusion
The Ilizarov method is an excellent choice for managing massive bone defects accompanied with local infection.A principal disadvantage is a prolonged treatment time, that demands good selection and preparation of patients.It is very important to mention a long learning curve and the need to plan the well-timed education.