Treatment of diaphyseal forearm defects caused by infection using Ilizarov segmental bone transport technique

The forearm is a complex joint mechanism and not just two separate bones. The integrity of the anatomical structures is vital for a comprehensive function and synergistic effect, especially for the pronation and supination [28]. There is no doubt that the management of a segmental diaphyseal defect in the forearm is a difficult task for surgeons, especially combined with deep infection. It is so important to reconstruct the forearm function and control the infection process simultaneously.

Various methods have been proposed to treat bone defects in the forearm, including corticocancellous bone graft, nonvascularized fibular graft, vascularized fibular graft, Masquelet’s induced membrane technique, and bone transport [4‐6, 9, 10, 12, 26, 27, 32]. Prasarn et al. [33] conducted iliac crest graft in 12 cases with the average defects measured 2.1 cm in the forearm and achieved union in all patients. Although bone graft is an effective method for bone defects, it is not recommended for the defects exceeds 5 cm due to the risk of resorption [34], nonunion, and fracture of the graft [35]. Vascularized fibular graft has a high success rate, but it is technically demanding and has a potential donor site morbidity. Adani et al. [36] performed vascularized fibular graft in 10 patients with an average forearm bone defect of 8.4 cm and achieved union in 9 of 10 patients. Gore et al. [37] reported there was mild muscle weakness after the partial fibula was removed, and Gonzalez et al. [38] declared that there was a statistical link between valgus and the removal of the partial fibula. The Masquelet technique has the advantage of managing the segmental bone defects and required no advanced skills in microvascular surgery, but the outcome is difficult to predict, especially in post-infective defects [39].

Ilizarov bone transport technique, an effective and minimally invasive method that can preserve the biomechanical microenvironment needed for fracture healing, is the preferable option for the treatment of massive bone defect [12, 13, 20, 21, 24]. As early as 1996, Esser had performed a segmental bone transport on a patient who had a posttraumatic defect of his left forearm [2]. The surgery led to complete bone healing, with the patient resuming his activities as a worker. Subsequently, Smith et al. [3] reported 11 consecutive patients with traumatic forearm bone loss who were treated with Ilizarov ring fixation, and the treatment resulted in ablation of infection, healing of atrophic non-unions with minimal complications, and early extremity use. Qun Zhang et al. [26] performed bone transport to treat 16 infected forearm nonunion and acquired satisfied functional results, concluding that radical debridement is the key step to control bone infection. Tang Liu et al. [27] retrospectively reviewed a consecutive series of 21 patients who were treated for the forearm infected nonunion by bone transport, and they concluded that the technique of bone transport after debridement is a safe, effective, and minimally invasive treatment for forearm infected nonunion. Satisfactory outcomes the two studies above gained, while failed to provide more detailed functional scores at the last clinical visit. Recently, Kliushin et al. [28] also reported a 43 years old man with an infected ulnar defect and dislocated radial head due to infected Monteggia fracture, and the patient was successfully treated by Ilizarov bone transport after failed attempts by a bone spacer and fibular graft.

Although the bone transport technique has been used widely, inevitable difficulties as complications that may affect the procedure have been reported by many studies [14, 24, 40]. Pain and pin site infection are common in our study as expected. The other complications, as pin loosening, axial deviation, soft tissue incarceration, delayed union, and nonunion, are also observed. They are all successfully treated with kinds of methods. The key factors we realized to prevent or minimize complications are particular attention, patient compliance, and the surgeon’s experience. Furthermore, our clinical experience has shown that the volume of antibiotic bone cement should be larger than that of the resected bony fragment to create a large enough space, so as to reduce the risk of soft tissue incarceration during the procedure of bone transport.

In the present study, the external fixation index (mean 46.2 days/cm, range 40.9 to 61.8 days/cm) was higher than that in previous study [13, 24, 26, 27] (mean 45.4 days/cm, range 42 to 48.9 days/cm). We considered that the mechanism of bone defect in our study was responsible for this matter. The radical debridement leads to the destruction of the microenvironment for bone regeneration, both docking union and regenerate maturation thereby underwent an excessive duration. Although the range of motion of the wrist, elbow, and forearm are not back to normal, especially for the pronation and supination in the forearm, the functional results were satisfactory with a mean DASH score of 13.8 (5 to 26) and a mean modified Mayo wrist score 83.8 (65 to 90) in our study. There is only a moderate disability in activities of daily life. To recover the forearm function in our experience, intensive physiotherapy should be emphasized during the whole procedure, including the range of motion exercises for the fingers, wrist and elbow within the tolerance of pain from the second day after the operation. The patients were also encouraged to train the affected limbs by pushing the wall as stress simulation [26, 27].

Bone transport can be performed by different types of external fixation. The circular external fixator is not conducive to the functional exercise of the forearm, and the restriction of pronation and supination can exacerbate the functional impairment. Therefore, a monolateral external fixation system without tensioned transfixion wires was used in our study. It is beneficial to the rotation of the forearm, and there is less risk of neurovascular damage [41]. A large amount of movement in the forearm may lead to the loosening of the pins. We recommend using hydroxyapatite-coated Schanz screws to prevent the complications, especially for the patient with osteoporosis. For proper bone transport technique, the most crucial procedure is that the length and alignment of the injured bone must be restored firstly with reference to the contralateral same bone. Besides, the injured bone should be fixated at the neutral position of the forearm and the elbow positioned at 90° in our experience due to the interosseous membrane is most relaxed in this position, and it can reduce the risk of displacement caused by muscle tension.

When conducting an osteotomy on the injured bone, we recommend the use of the Gigli Saw technique. The periosteum may have less regenerative and reparative potential, and the injury to the periosteum may lead to ischemia or necrosis of the underlying bone ends. The subperiosteal Gigli saw osteotomy technique is especially advantageous with bone defect cases to preserves the periosteum while completely transecting the endosteum and eliminates the possibility of an incomplete corticotomy with minimal soft tissue dissection [42].

Our study described an effective alternative technique for the management of bone defects caused by an infection in the forearm. The consecutive stages contain eradication of infection, restoration of bone defect, proper length regain of the injured bone, union achieved and better functions of the wrist and elbow obtained. The most crucial step is radical debridement of the infectious tissues as a priority to establish mechanical stability of the bony fragments and biological stimulation of the bone in our experience. The procedure is lengthy, with a considerable risk of complications. Appropriate insertion of pins, stability of the transport system, meticulous care, and careful attention contribute to ensuring satisfactory results.

The present study had several limitations. Longer follow-up is necessary to evaluate the clinical efficacy better. The absence of a control group and the relatively small sample size required a conservative attitude when interpreting the outcomes of this study. Multi-centered trials with a larger sample size should be conducted in further investigations.