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We present the results of treatment of 100 patients (72 men, 28 women) by the Ilizarov method of bone transport using circular (55) and monolateral external fixators (45). A total of 26 femurs (18 monolateral, 8 circular) and 74 tibias (49 circular, 25 monolateral) was examined. There were no significant differences between the circular fixator and the monolateral fixator with regard to treatment time, complications in the treated bone segments or compliance with the presence of the fixator. The main complications (pseudoarthrosis at bone contact points after transport, insufficient ossification of lengthened bone, knee stiffness) were resolved with further treatment for all patients with the exception of one case which continued with repeated infections. The circular fixator allows for deformity corrections during bone transport but the monolateral fixator is tolerated better by patients, especially in those with femoral defects.
Bone transport according to the Ilizarov method is widely practised in reconstructive surgery. There are many external fixators which are designed to achieve the surgical objective of managing bone defects using the principles of distraction osteogenesis. We present our clinical experience of 100 consecutive cases of bone transport (26 femurs, 74 tibias) treated with monolateral and circular external fixators. We include a review of the literature [1–10] and report our results according to the bone segments treated, technical variations, complications and the solutions adopted.
Our sample contains 100 patients (72 men, 28 women) with a mean age 34.6 (11–75). There were 55 patients treated with the Ilizarov circular fixator (Amplimedical s.p.a, Milano) and 45 patients treated with the LRS monolateral rail (Orthofix SRL, Verona). A total of 26 femurs (18 treated with the monolateral device and 8 with the circular fixator) and 74 tibias (49 circular fixator, 25 monolateral) were reviewed. A single level bone transport was performed in 80 patients [descending technique in 50 tibias (Figs. 1, ,2)2) and 12 femurs (Fig. 3); ascending technique in 13 tibias and 5 femurs (Fig. 4)], and a double level bone transport in 10 tibias (6 with mid-diaphyseal contact of transported bone ends from proximal and distal metaphyseal osteotomies, and 4 serial “twins” from a double proximal osteotomy) and 5 femurs (all with mid-diaphyseal contact). In 5 cases (2 tibias, 3 femurs), we performed a variation of the bone transport technique through immediate shortening by 15% and subsequent lengthening.
The pathologies causing bone loss, either directly or indirectly from surgical resection, were as follows:
The average bone defect after resection was 8.4 cm (3–19).
In the tibia, the assembly comprised of 5 rings: 2 proximal rings, 1 for transport and 2 distal. Two Kirschner wires were inserted and tensioned for each of the proximal and distal rings; 2 screws coated with hydroxyapatite were applied to the ring used for transport (on the medial subcutaneous surface for the tibia and laterally for the femur) in order to reduce skin problems from the crossed wires. In the femur, a mixed assembly with arches and proximal screws was used with 1 ring for transport and 2 distally. The osteotomy was performed with a Gigli saw  after the fixator was applied. Bone transport was commenced 5 days after osteotomy at an average rate of 1/3 mm every 8 h.
The LRS rail fixator was applied using hydroxyapatite-coated screws: 3 proximal, 3 intermediate for transport and 3 distal. In cases where the resection margins could be determined pre-operatively and the focus of infection identified, the rail fixator was applied first prior to performing the resection. This facilitated maintenance of alignment between proximal, intermediate and distal bone segments. A “crown” osteotomy was performed in the healthy bone tissue to permit distraction in accordance with the callotasis technique . Distraction in order to produce bone transport was started 10 days after surgery at a rate of 1 mm/day.
The process of distraction osteogenesis is associated with an increase in the local blood supply to the limb. For example, in an open tibial fracture with bone loss which needed vascular reconstruction using a bypass graft, two arteriograms which were carried out before and after transport showed an improvement in the vascularization of the foot (Fig. 5).
The following factors in surgical technique were common to both groups irrespective of the type of fixator used:
The process of bone transport is associated with problems, obstacles and complications . We have chosen not to differentiate the difficulties encountered into these groups as we note all types to be clinically relevant. Including cases with complications, the total treatment time ranged from a minimum of 5 months to a maximum of 2 years. The average follow-up was 6 years (min. 2, max. 14). In 96 cases, bone transport led to normal neoformed bone. In our consecutive 100 cases, we observed a variety of complications known to be associated with the bone transport technique. These were as follows:
This review allows us to confirm previously reported data and to highlight some aspects of the technique.
This is necessary to remove necrotic and infected bone and soft tissue. Resection must be radical and cross over into healthy tissue. In order to ascertain the vitality of the residual bone, it is best to drill several holes into the bone ends and observe bleeding with the tourniquet deflated. Samples of removed tissue should be examined both histologically and microbiologically. Collaboration with a specialist in infectious diseases is essential for appropriate antibiotic therapy.
This was carried out with the “crown” technique in 45 cases and with a Gigli saw in 55 cases without significant differences in the quality of the newly formed bone.
The transported segment of bone was almost always held with 3 screws in the axial fixator and with 2 in the circular. The extra screw is advisable in the monolateral fixator because it improves stability and reduces the risk of osteolysis. Although the diameter of the screws is greater than that of the tensioned wires, the screws were tolerated better. This is especially true of the tibia where the screws are inserted through the medial subcutaneous surface which not being covered by muscle is tolerant of the presence of screws.
In osteoporotic bone and where the bone ends need to be transported for less than 5 cm, we found it preferable to increase the latency period after osteotomy to 10 days and reduce the rate to 0.5 mm/day, at least for the first 10 days. Ultrasound imaging will provide an indicator of the quality of osteogenesis and the possibility of accelerating distraction.
In our opinion, this should always be explored surgically. In the light of the results obtained, and especially for the last 50 cases, we believe that, in the tibia, it is always necessary to remove interposed fibrous tissue and sometimes even cutaneous tissue (skin) whilst maintaining external fixation. Skin, especially in transport involving more than 3 cm, caps the transported bone end. This needs to be freed and the bone ends carefully abraded with autoplastic grafts to accelerate consolidation. In these cases, especially those from a proximal–distal bone transport, the circular fixator gives better results as the disconnection of the two most distal rings allows reduction and optimal alignment of the two docking ends. This is then stabilised by re-connecting the rings. In the femur, we believe that the most effective method of solving nonunion of the docking site is by intramedullary nailing, this is with prior reaming of the medullary canal in order to remove all fibrous interposed growth and to prepare the site for reduction (Fig. 4).
An acute reduction of the size of bone defect by shortening the limb decreases treatment times because the two ends can be reduced and consolidate earlier. Shortening may reach 15% in the femur. The tibia cannot be shortened by more than 10% due to the risk of a compartment syndrome. In addition, resection of the fibula also requires further optimal corticalisation of the tibia before the fixator can be removed. However, this modification of the classic bone transport method is effective in the femur but should be avoided in the tibia. This is because it is preferable to maintain the continuity of the fibula except where trauma has already caused a gap of a few centimetres in the fibula.
This can decrease bone transport times and is carried out by osteotomy of both proximal and distal femoral and tibial metaphyses and bringing the transported ends into contact with each other in the mid-diaphyseal region. Twin transport, with the bone ends both being taken in the same direction, is less effective. In the 4 cases of twin tibia transport, we encountered long corticalisation times of the newly formed regenerate bone from the more distal osteotomy, which is usually carried out in the diaphysis.
Circular fixators are heavier and more uncomfortable for the patient, especially in assemblies on the thigh, and were found to be associated with longer medication times in this series. However, an advantage is that the assembly can be adjusted and modified without return to the operating room unless there is need for re-implantation of wires or screws during the transport procedure. Another advantage is in the tibia where, in proximal–distal bone transport, the two distal rings can be disconnected from the main assembly to allow access for surgical debridement of the docking site and for optimal reduction of the transported end to the distal tibia, and this followed by re-connection of the two rings. The experiences we have gathered in this series have led us to choose a monolateral fixator for femoral problems and the circular type for the tibia although we recognise that surgery should be planned with the possibility of using both types.
We present the results of 100 consecutive cases of bone transport with particular reference to the complications and their management. Bone transport is a reliable method for reconstruction of bone defects in the femur and tibia and remains a safe treatment for resection after bone infection. The prolonged treatment times and the need for repeated prescriptions for medication make this form of surgery inadvisable for the socially disadvantaged, those with poorly managed mental illness or those without a supportive family environment. Limb ablation by amputation is an alternative means of treatment and should be considered when local and patient-related factors indicate it is a preferred option.