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JINJ-6054; No. of Pages 6 Injury, Int. J. Care Injured xxx (2015) xxx–xxx
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Injury journal homepage: www.elsevier.com/locate/injury
Application of 3D printed customized external fixator in fracture reduction Feng Qiao a,*, Dichen Li b,c, Zhongmin Jin c,d, Yongchang Gao c, Tao Zhou c, Jinlong He a, Li Cheng a a
Department of Orthopaedics, Hong-Hui Hospital, Xi’an Jiaotong University College of Medicine, No.555, Youyidong Rd., Xi’an, Shaanxi 710054, China Department of Orthopaedics, Second Affiliated Hospital, Xi’an Jiaotong University, Xi’an, Shaanxi 710004, China State Key Laboratory for Manufacturing System Engineering, School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710054, China d Institute of Medical and Biological Engineering, School of Mechanical Engineering, Uinversity of Leeds, LS2 9JT, UK b c
A R T I C L E I N F O
A B S T R A C T
Article history: Accepted 12 January 2015
Introduction: Long bone fracture is common in traumatic osteopathic patients. Good reduction is beneficial for bone healing, preventing the complications such as delayed union, nonunion, malunion, but is hard to achieve. Repeated attempts during the surgery would increase the operation time, cause new damage to the fracture site and excessive exposure to radiation. Robotic and navigation techniques can help improve the reduction accuracy, however, the high cost and complexity of operation have limited their clinical application. Materials and methods: We combined 3D printing with computer-assisted reduction technique to develop a customised external fixator with the function of fracture reduction. The original CT data obtained by scanning the fracture was imported to computer for reconstructing and reducing the 3D image of the fracture, based on which the external fixator (named as Q-Fixator) was designed and then fabricated by 3D printing techniques. The fracture reduction and fixation was achieved by connecting the pins inserted in the bones with the customised Q-Fixator. Experiments were conducted on three fracture models to demonstrate the reduction results. Results: Good reduction results were obtained on all three fractured bone models, with an average rotation of 1.218(0.24), angulation of 1.848(0.28), and lateral displacement of 2.22 mm(0.62). Conclusions: A novel customised external fixator for long bone fracture reduction was readily developed using 3D printing technique. The customised external fixator had the advantages of easy manipulation, accurate reduction, minimally invasion and experience-independence. Future application of the customised external fixator can be extended to include the fixation function with stress adjustment and potentially optimise the fracture healing process. ß 2015 Elsevier Ltd. All rights reserved.
Keywords: 3D printing Computer-assisted surgery Long bone fracture Closed reduction External fixator
Introduction Lower limb long bone fracture is common in traumatic orthopaedic patients [1,2]. Inappropriate treatment would increase the risk of complications such as nonunion, malunion, secondary fracture and breakage of fixation devices [3–6]. The contact of the viable bones would benefit bone formation and healing [7,8]. Lawyer and Lubbers found that fractures, classified as anatomically reduced, healed in an average of 5.1 months, faster than those classified as not anatomically reduced, which required
* Corresponding author. Tel.: +86 13991941892. E-mail address:
[email protected] (F. Qiao).
an average of 8.2 months to heal [9]. Although open reduction can achieve better reduction result, it would damage soft tissues and blood supply, leading to high margin of nonunion and delayed union [10,11]. Therefore, closed minimally invasive surgery is preferred for long bone shaft fracture. However, closed reduction surgery is hard to conduct and repeated attempts during the surgery would increase surgery time, cause new damage to the fracture site and increase the harm for surgeons and patients due to excessive exposure to radiation. Furthermore, the reduction accuracy is not guaranteed by this process, and the rotational deformity is one of the biggest issues [12–14]. To improve reduction accuracy and decrease the radiation time (the exposure time can often reach 5–10 min [15]), recently, a number of studies have focused on the application of robotic and
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navigation techniques in fracture reductions. With the advantages of automatic operation, radiation-resistance and high accuracy, robot was recognized as an appropriate approach to help reduce long bone shaft [16–18]. Leloup et al. [19] and Kahler et al. [20] studied the navigation method based on the 3D model of the bone for improvement of reduction accuracy, however, Oliver KeastButler et al. [21] reported its inability to significantly increase the rotational alignment accuracy. Besides, the navigation system, which cannot reduce the fracture directly, is only an auxiliary method to assist the surgeons. Therefore, it is unable to shorten the operation time, combined with their disadvantages such as high cost and complexity of operation, and has not been widely used clinically. External fixator is an old and well-established method of treatment for fractures, but is not the first choice in modern orthopaedic trauma surgery. It mainly serves as a temporary fixator for open wounds and soft tissue injuries [22,23]. Taylor et al. invented a computer-assisted reduction fixator in1994, i.e. Taylor Spatial Frame Fixator (TSF) [24]. Computer was used to calculate the required length of six struts based on measuring the posteroanterior and lateral X-ray images. Then the reduction was realised through adjusting the struts. The TSF can improve the reduction accuracy and reduce the radiation, though the quality of X-ray and measurement error would significantly impact the reduction performance. Koo et al. [25] designed a bone reposition device (BRD) for reduction, which was based on the CT data and used seven adjustable struts. The experiments on the model bone showed excellent reduction performance. However, in clinical application, due to the muscular tension, the struts may not be adjusted to the length required and thus, the aggregated error of the seven struts would deteriorate the overall performance. In addition, other shortcomings of BRD, such as the complex structure, complicated operation and poor stability due to its unilateral structure, also prevented its clinical application. As 3D printing technology matures, this new technique is widely applied in the fields such as architecture, industrial design, and aerospace industry. In orthopaedics, this technique was mainly applied in the areas of anatomical models for diagnosis and surgical planning, and customised joint implants [26,27]. However, to the best knowledge of the authors, there were no reports on
combination of 3D printing with computer-assisted technique to create any external fixators in treating bone fractures. The paper presented the first 3D printed customised external fixator for fracture reduction and fixation. Experiments on three cadaveric and model bones demonstrated its excellent reduction function and simplicity in operation.
Materials and methods Structure of Q-Fixator Structure: The Q-Fixator, abbr. QF, is named after its shape, which looks like ‘‘Q’’ from the top vie as shown in Fig. 1. The QF is a customised external fixator with reduction function, consisting of proximal frame (a) and distal frame (b). The frame is made of photosensitive resin and manufactured by 3D printing. The two frames are connected by four parallel 6 mm diameter threaded rods (1), attached through adjustable nuts (2), which control the distance between the two frames. Three to four mounting holes (3) on each frame are used to connect the frames and bone by inserting pins (4) through them. For the sake of simplifying the installation of fixator, each frame is divided into two parts joined by bolts. The frames can be optimised by reducing excessive materials and strengthened according to the state of stress. When clinically applied, two accessory metal rings can be attached to each frame to improve the stiffness of the fixator. The fixation principle of QF is the same as that of the Ilizarov apparatus. In both fixators, pins, inserted into bones, are used to link the bones with distal the proximal frames or rings. Two frames or rings are connected by four parallel threaded rods. The structure can provide stable fixation, and strong anti-rotation and antibending abilities [28], preventing the shear and rotary forces. Since the threaded rods are parallel to the line of force through the bone, this structure enables adjustment of compressive loading through the nuts on rods and micro-movement at the fracture sites, which has a beneficial effect on bone healing [29]. However, the operation and installation principles applied by QF are different, which has low demand for the location and direction of pin insertion, surgeons’ experiences and skills. Fracture reduction by the computer-aided QF is less experience-dependent, easier to be
Fig. 1. Structure of Q-Fixator (a) proximal frame; (b) distal frame. The frame is made of photosensitive resin and manufactured by 3D printing. (1) Threaded rods; (2) adjustable nuts; (3) mounting holes; (4) pin and half-pin; (5) connecting holes; (6) metal rings, which can improve the stiffness of the fixator.
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operated and more accurate, compared with the Ilizarov apparatus.
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Design and manufacture of QF
Three fracture models, including 1 foam femur, 1 cadaveric femur and 1 cadaveric tibia, were used in the experiment. A saw cut was made in the middle of each bone, the fracture types were respectively AO type 32A2, 32A2, and 42B2. Two to three pins (3 half-pins or 2 pins or 1 pin + 2 half-pins) were inserted proximally and distally (Fig. 2a). All the pins were aimed to penetrate the cortex on both sides. The models were wrapped with opaque soft cloth, making the bones invisible during fixator installations to avoid the effect of visual observation and experience.
The data obtained by model reduction were imported into design software (solidworks) and then used to determine the size of the frame based on the leg size and fracture position (Fig. 3b). The direction of the connection rods was made parallel to the line of force through the bones and the mounting holes were made to coincide with the new fixation pin positions (Fig. 3c). To simplify the installation, each frame was divided into two parts (Fig. 3d). In order to assure the feasibility of the designed fixator, the installation of the fixator was carried out on computer firstly. Then the data generated from the computer was delivered to the Rapid Form Machine (SPS600B, Xi’an Jiaotong University, China) for manufacturing using photosensitive resin materials (Fig. 3e).
3D Fracture images reconstruction & model reduction on computer
Assemble QF to complete fracture reduction
The CT data obtained by scanning the fracture was imported to computer for reconstructing the 3D image of the fracture (Fig. 2b). The image, based on the state of the fracture, was divided into subimages containing each fractured fragment. Each bone fragment would generate a sub-image. Based on the surface features and shapes of bones, the fractured fragments were reduced by combining these sub-images through rotation and transformation on the computer (Fig. 2c). The accuracy of fracture reduction and line of force was ensured by visually observing the line of force and reduction circumstance in 3D view (Fig. 2d). To reaffirm the accuracy of the fracture reduction, 2D cross-sections were cut from the 3D model reduction images (Fig. 2e), and visually inspected. The whole process was continued until the best accuracy of the simulated reduction on computer was achieved. After confirming its accuracy, the sub-images were integrated to a new image and the simulated fracture reduction process was completed. As a result, new positions for the fixation pins were obtained.
The proximal frame was connected with the fixation pins on the proximal bone segment so that the proximal frame, fixation pins and bone segments became integral. Then, the distal part was connected in the same way (Figs. 4a and Fig. 3f). Two same-sized metal rings were attached to the upper and lower frames to increase the stiffness. The bones were dragged to make the fracture site apart. The proximal and distal frames were connected with the threaded rods based on the plan generated by the computer (Figs. 3g and Fig. 4b). Finally, the nuts were screwed to finish the reduction. For the comminuted fracture, after CT scanning was conducted, the third bone segment was attached with the proximal segment visually before the fixator was assembled. Because the direction of the connection rods was made parallel to the line of force through the bones, the axial stress and distance between the distal and proximal bone segments can be increased and decreased by screwing the adjustable nuts (Fig. 4c).
Preparation of fracture model
Fig. 2. 3D fracture images reconstruction & model reduction on computer.
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Fig. 3. Design and manufacture of QF. (f) Connect the bones with frames by inserting and fixing pins through mounting holes. Metal rings can be attached to strengthen the fixator.
Measurement parameters and method The binocular 3D measurement system (Xi’an Jiaotong University, China) was used to obtain the reduction data with regard to the rotation and displacement in each direction in order to demonstrate the efficiency of the proposed QF based on the method reported in [30]. A set of markers, before breaking the model bone, were located at the proximal and
distal part for collection of the initial data. After reduction, a new set of data was collected and compared with the initial one to calculate the rotation, angulation and lateral displacement errors. Source of funding There is no external funding for this study.
Fig. 4. Connect QF and adjust pressure on fracture site. (a) Connect the frame and pins; (b) connect the distal and proximal frames; and (c) screw the nuts to adjust the stress of fracture site.
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Results Based on the above method, we obtained the parameters of fracture misalignment of three model bones, as shown in Table 1. The rotation accuracy achieved with the Q-Fixator alone was 1.218(0.24), angulation of 1.848(0.28), and lateral displacement of 2.22 mm (0.62). Discussion Since the position and direction of the mounting holes in QF vary among different fracture conditions of different patients, standard designs would not be suitable for such applications, and customised designs are generally required. 3D printing technology is ideally suited for such complex geometries and structures in terms of speed and accuracy. 3D printing is an additive manufacturing process to create complex and different shapes, where the 3D printable models can readily be manufactured, based on the CAD data. In the present study, we reconstructed 3D images of the fracture through computer software, conducted model reductions on computer, designed the external fixator QF based on the new positions of bones and pins after model reduction and finally manufactured the QF by 3D printing technique. The experimental results demonstrated satisfactory reduction accuracy on model bones. Accurate reduction using QF was achieved by the following factors: reduction accuracy of fracture image, manufacturing accuracy and assembly of the fixator. Firstly, we used 3D image to achieve accurate reduction, which is unconstrained by the field of vision and operating time and easy to judge the rotation and angulation. Secondly, the manufacturing error of 3D printing system we used was no greater than 0.1 mm. Thirdly, the Q-Fixator was designed to have circular frames to ensure stability. Furthermore, the material we selected was photosensitive resin with sufficient stiffness. And in clinical practice, additional accessory metal rings can be added on the frames to further improve the stiffness of the fixator. Fourthly, all the connections were achieved automatically without surgeon interference. Therefore, the error in each process was sufficiently small to ensure the excellent overall reduction results by QF. Compared with the results shown in [21] reduced by existing techniques, the reduction accuracy was largely improved. It is well known that the accurate anatomical reduction can reduce the time of union, improve the function after the reduction of long bone fracture and decrease the possibility of malunion and nonunion [31–33]. However, the accuracy associated with close reduction is generally limited. A summary from previous studies has shown that at least 20% patients had rotational errors greater than 108 following intramedullary nailing [21], in some cases even reaching 34% [34]. In the multicentre clinical study conducted by Jaarsma et al. [35], 28% of the patients with femoral fractures had a rotation greater than 158, which required a secondary surgery to reduce the deformity. Therefore we would expect the accurate reduction achieved with QF would facilitate bone healing. In addition, instead of relying on the guidance of X-ray imaging equipment, or surgeon’s experience to try repeatedly, the
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reduction procedure by using QF was only a 3–5 min process to connect the fixator. If the metal rings were required to strengthen the fixator, the process would be prolonged to 6–8 min. For this reason, QF can obviously simplify the operation, shorten the operation time, and avoid excessive radiation and new damage due to the repeated reduction operations. The computer-assisted customised Q-Fixator manufactured by 3D printing technology introduced in this paper was demonstrated to be reliable in long bone fracture reduction especially in rotation reduction from the experiments on the tibia and femur fracture model. The rotational deformities of three fracture models were all satisfactorily reduced. Better reduction results were achieved, than those of fractures reduced by existing methods. During the model reduction on computers, due to the round-shaped cross section of femurs, it was not an easy task to judge the rotation even based on the 3D view. The accuracy of the fracture reduction should be reaffirmed by the 2D cross-sections (as shown in Fig. 2e). Thus, one could imagine the reduction difficulty by traditional method, which is based on the 2D fluoroscopic images. However the triangular-shaped cross section would facilitate the judgment of rotational reduction in tibia. Our findings are consistent with the previous observation by Jaarsma et al. [35]. Since the connecting rods of QF were parallel with the line of force through the bone, we could control the length of bone by the nuts on the rods to prevent overlap and separation. The fracture was reduced satisfactorily through the whole process. After reduction by QF, the angulation and rotation were found comparatively small, while the lateral displacement was greater than the other parameters. This may be caused by the structure of the fixator. As we could see from the structure diagram, three pins on each frame were used for preventing rotation, and the machining error of the positions of mounting holes in each frame was only 0.1 mm. In addition, a full pin instead of half-pin fixation method had preferable anti-rotation ability. Thus, the rotation was reduced markedly. Rotation in the experiment results could be related to the operating error during the model reduction on computer, however, based on the surface features of the bones as well as the 2D cross section image, rotation can be well controlled. Since the pin used to prevent lateral displacement was a half-pin (the full pin is not allowed in some parts of human body) and there was a distance between the pin and the fracture site, a small change of shape or a small error in the position and angle of the pin would cause comparatively large lateral displacement. In clinical use, in accordance with the direction of lateral displacement, Schanz screw can be added near the fracture site to achieve better reduction result. Since the Q-Fixator was designed on the same principle as the Ilizarov apparatus, we would expect that QF is also a stable fixator, as stability is one of the main advantages of Ilizarov apparatus. Future work is required to optimise and test the design from a load bearing consideration to ensure adequate mechanical performance before clinical applications. Currently, fabrication of the QF using the current 3D printing technique took about 20 h, which means that, after insertion of the fixation pins, patients would have to wait for 20 h before the fixator to be assembled. In clinical
Table 1 Fracture misalignment after reduction. No.
AO type
Rotation (8)
Axial angulation (8)
Radial angulation (8)
Axial displacement (mm)
Radial displacement (mm)
1 2 3
32A2 32A2 42B2
1.28 1.41 0.94 1.21 0.24
1.32 1.88 2.13
2.04 1.81 1.86
2.78 1.97 2.51
2.27 2.69 1.11
SD
1.84 0.28
2.22 0.62
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applications, a hybrid external fixator could be used as a temporary fixator after inserting the pins. This would reduce the pain of the patients while the fixator is designed and manufactured. The development of computer software and 3D printing technologies, as well as the potential combination of standard modular components with limited customised components, should greatly reduce the fabrication time of the QF. Consequently, the patient’s waiting time should be shortened accordingly. Furthermore, with the development of new materials suitable for 3D printing and yet with adequate mechanical properties as well as optimised structure, the use of the metal rings for the purpose of strengthening of the QF may not be necessary, and even unilateral fixators could be designed and manufactured in a similar way. This will simplify the assembly and the operation, and reduce the operation time even further. For the clinicians, it is difficult to master the computer software. However, more and more support services are becoming available, and often provided via internet. This provides a platform for a close cooperation between doctors and engineers. Therefore this method could be applied practically in clinical applications. Ultimately in the future, fractures may be treated in Accident and Emergency. Conclusion A novel customised external fixator QF was designed and fabricated successfully through 3D printing technique with the automatic reduction function, the advantages of accurate reduction, minimally invasion, stable fixation and potential flexible stress adjustment to improve the healing of long bone shaft fracture. In addition, it was easy to operate, which could shorten the operation time, avoid the repeated radiation and lower the requirement for the experience of the surgeons. It has a bright prospect for clinical application. Conflict of interest The authors declare that they have no conflict of interest. References [1] Arneson TJ, Melton LJ, Lewallen DG, Ofallon WM. Epidemiology of diaphyseal and distal femoral fractures in Rochester. Clin Orthop Relat Res 1988;188–94. [2] Friedlaender GE, Perry CR, Cole JD, Cook SD, Cierny G, Muschler GF, et al. Osteogenic protein-1 (bone morphogenetic protein-7) in the treatment of tibial nonunions – a prospective, randomized clinical trial comparing rhOP-1 with fresh bone autograft. J Bone Joint Surg Am 2001;83A. S151-S8. [3] Perren SM. Evolution of the internal fixation of long bone fractures – the scientific basis of biological internal fixation: choosing a new balance between stability and biology. J Bone Joint Surg Br 2002;84B:1093–110. [4] McGraw JM, Lim EVA. Treatment of open tibial-shaft fractures, external fixation and secondary intramedullary nailing. J Bone Joint Surg Am 1988;70A:900–11. [5] Phieffer LS, Goulet JA. Delayed unions of the tibia. J Bone Joint Surg Am 2006;88A:206–16. [6] Bhandari M, Guyatt G, Tornetta III P, Schemitsch EH, Swiontkowski M, Sanders D, et al. Randomized trial of reamed and unreamed intramedullary nailing of tibial shaft fractures. J Bone Joint Surg Am 2008;90A:2567–78. [7] Rubin C, Turner AS, Bain S, Mallinckrodt C, McLeod K. Anabolism – low mechanical signals strengthen long bones. Nature 2001;412:603–4. [8] Hente R, Fuchtmeier B, Schlegel U, Ernstberger A, Perren SM. The influence of cyclic compression and distraction on the healing of experimental tibial fractures. J Orthop Res 2004;22:709–15.
[9] Lawyer RB, Lubbers LM. Use of the Hoffmann apparatus in the treatment of unstable tibial fractures. J Bone Joint Surg Am 1980;62:1264–73. [10] Leunig M, Hertel R, Siebenrock KA, Ballmer FT, Mast JW, Ganz R. The evolution of indirect reduction techniques for the treatment of fractures. Clin Orthop Relat Res 2000;7–14. [11] Kolodziej P, Lee FS, Patel A, Kassab SS, Shen KL, Yang KH, et al. Biomechanical evaluation of the schuhli nut. Clin Orthop Relat Res 1998;79–85. [12] Citak M, Oszwald M, O’Loughlin PF, Citak M, Kendoff D, Huefner T, et al. Threedimensional measurement of femoral antetorsion: comparison to a conventional radiological method. Arch Orthop Trauma Surg 2010;130:513–8. [13] Citak M, Kendoff D, Gardner MJ, Oszwald M, O’Loughlin PF, Olivier LC, et al. Rotational stability of femoral osteosynthesis in femoral fractures – navigated measurements. Technol.Health Care: Off J Eur Soc Eng Med 2009;17:25–32. [14] Salem KH, Maier D, Keppler P, Kinzl L, Gebhard F. Limb malalignment and functional outcome after antegrade versus retrograde intramedullary nailing in distal femoral fractures. J Trauma – Inj Infec Crit Care 2006;61:375–81. [15] Wilharm A, Gras F, Rausch S, Linder R, Marintschev I, Hofmann GO, et al. Navigation in femoral-shaft fractures-from lab tests to clinical routine. Injury – Int J Care Inj 2011;42:1346–52. [16] Hung S-S, Lee M-Y. Functional assessment of a surgical robot for reduction of lower limb fractures. Int J Med Robot Comput Assist Surg 2010;6:413–21. [17] Peifu T, Lei H, Hailong D, Minli G, Lihai Z. Novel 3D hexapod computer-assisted orthopaedic surgery system for closed diaphyseal fracture reduction. Int J Med Robot Comput Assist Surg 2012;8:17–24. [18] Westphal R, Winkelbach S, Huefner T, Faulstich J, Martin P, Krettek C, et al. A surgical telemanipulator for femur shaft fracture reduction. Int J Med RobotComput Assist Surg 2006;2:238–50. [19] Leloup T, El Kazzi W, Schuind F, Warzee N. Conception of a navigation system controlling diaphyseal fracture reduction treated with external fixation. Int J Med Robot Comput Assist Surg 2009;5:99–109. [20] Kahler DM. Navigated long-bone fracture reduction. J Bone Joint Surg Am 2009;91A:102–7. [21] Keast-Butler O, Lutz MJ, Angelini M, Lash N, Pearce D, Crookshank M, et al. Computer navigation in the reduction and fixation of femoral shaft fractures: a randomized control study. Injury – Int J Care Inj 2012;43:749–56. [22] Bhandari M, Guyatt GH, Swiontkowski MF, Tornetta P, Hanson B, Weaver B, et al. Surgeon’s preferences for the operative treatment of fractures of the tibial shaft – an international survey. J Bone Joint Surg Am 2001;83A:1746–52. [23] Checketts RG, Young CF. (iii) External fixation of diaphyseal fractures of the tibia. Curr Orthop 2003;17:176–89. [24] Feldman DS, Shin SS, Madan S, Koval KJ. Correction of tibial malunion and nonunion with six-axis analysis deformity correction using the Taylor spatial frame. J Orthop Trauma 2003;17:549–54. [25] Koo TK, Chao EY, Mak AF. Development and validation of a new approach for computer-aided long bone fracture reduction using unilateral external fixator. J Biomech 2006;39:2104–12. [26] Bose S, Vahabzadeh S, Bandyopadhyay A. Bone tissue engineering using 3D printing. Mater Today 2013;16:496–504. [27] Giovinco NA, Dunn SP, Dowling L, Smith C, Trowell L, Ruch JA, et al. A novel combination of printed 3-dimensional anatomic templates and computerassisted surgical simulation for virtual preoperative planning in charcot foot reconstruction. J Foot Ankle Surg 2012;51:387–93. [28] Paley D, Fleming B, Catagni M, Kristiansen T, Pope M. Mechanical evaluation of external fixators used in limb lengthening. Orthop Relat Res 1990;50–7. [29] Leung KS, Cheung WH, Yeung HY, Lee KM, Fung KP. Effect of weightbearing on bone formation during distraction osteogenesis. Clin Orthop Relat Res 2004;251–7. [30] Xiao Z, Jin L, Yu D, Tang Z. A cross-target-based accurate calibration method of binocular stereo systems with large-scale field-of-view. Measurement 2010;43:747–54. [31] Green SA. Complications of external skeletal fixation. Clin Orthop Relat Res 1983;109–16. [32] Hay SM, Rickman M, Saleh M. Fracture of the tibial diaphysis treated by external fixation and the axial alignment grid: a single surgeon’s experience. Injury-Int J Care Inj 1997;28:437–43. [33] Egger EL, Gottsaunerwolf F, Palmer J, Aro HT, Chao EYS. Effects of axial dynamization on bone healing. J Trauma – Inj Infect Crit Care 1993;34: 185–92. [34] Stephen DJG, Kreder HJ, Schemitsch EH, Conlan LB, Wild L, McKee MD. Femoral intramedullary nailing: comparison of fracture-table and manual traction – a prospective, randomized study. J Bone Joint Surg Am 2002;84A:1514–21. [35] Jaarsma RL, Pakvis DFM, Verdonschot N, Biert J, van Kampen A. Rotational malalignment after intramedullary nailing of femoral fractures. J Orthop Trauma 2004;18:403–9.
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