Fixation of Iliac Avulsion Fracture Using Additive Manufacturing Titanium Mesh after DCIA Flap Harvesting: Case Report

Round 1

Reviewer 1 Report

In this paper, authors address an interesting topic that relates to the complications of the donor site after DCIA flap harvesting focusing in the treatment of iliac bone fracture. The paper needs an extensive edition of the English language. Many sentences in the manuscript are difficult to understand, as an example concerning the aim of the paper they state: "The purpose of this study was to introduce cases in which reconstruction of the iliac avulsion fracture using the patient-specific 3D printed implant".  They present 3 cases of iliac fractures after raising a DCIA flap, bicortical in one case and monocortical in 2 cases.  In my opinion, authors must state if the 3 cases presented are all cases with this complication in their series and  clarify the percentage of cases suffering this complication among the total number of cases of DCIA flaps they raised. May be also the proportion of cases with iliac bone fracture in respect to other complications of the donor site in their series of DCIA flaps should be referred. Although it is discussed later in the discussion as a general statement,  their indications for the selection of a bicortical or a monocortical bone flap and the preservation or not of the anterior iliac spine are not clear  and need clarification.  In case 1, it seems that a marginal resection of the mandible was performed. Indication for a microvascular flap in absence of a segmental resection should be clarified.In the Discussion, the first paragraph seems to discuss the disadvantages of using plates instead of bone flaps but it again is poorly expressed in the English version and irrelevant in my opinion for the  purpose of the article. Also on page 9, the Paragraph "However these methods also have some limitations...........risk of re-fracture due to space between surrounding bones and implants" is totally unclear. What methods are they referring to? . Finally they propose an open reduction with a patient-specific 3D-printed titanium implant for the iliac fracture fixation. The references concerning the use of this method either in the introduction or in the discussion are weak and the use of this treatment method for the referred iliac fractures needs a deeper discussion including other alternatives especially the possibility of conservative non-surgical treatment. Did the authors have other cases with this type of complication treated in a different way? 

Author Response

Dear Reviewer

Thank you for your kind review

I tried to revise the manuscript according to your comment

Sincerely.

 

In this paper, authors address an interesting topic that relates to the complications of the donor site after DCIA flap harvesting focusing in the treatment of iliac bone fracture.

1. The paper needs an extensive edition of the English language. Many sentences in the manuscript are difficult to understand, as an example concerning the aim of the paper they state: "The purpose of this study was to introduce cases in which reconstruction of the iliac avulsion fracture using the patient-specific 3D printed implant". 

• The purpose of this study is to introduce cases of reconstruction of an iliac avulsion fracture using the patient-specific 3D fabricated implant.

They present 3 cases of iliac fractures after raising a DCIA flap, bicortical in one case and monocortical in 2 cases.  In my opinion, authors must state if the 3 cases presented are all cases with this complication in their series and clarify the percentage of cases suffering this complication among the total number of cases of DCIA flaps they raised. May be also the proportion of cases with iliac bone fracture in respect to other complications of the donor site in their series of DCIA flaps should be referred.

• Case presentation

The 27 patients underwent reconstruction using iliac bone in Chosun Dental hospital from February 2013 to July 2019, of which 3 patients had iliac avulsion fractures. The complication rate was 13.64%. Old age, obesity, osteoporosis, co-morbidities, and improper harvesting technique are the risk factors for the fracture of the iliac crest after bone grafting[18-21]. But no correlation was observed between the fractured patients of this study and the above.

Although it is discussed later in the discussion as a general statement,  their indications for the selection of a bicortical or a monocortical bone flap and the preservation or not of the anterior iliac spine are not clear  and need clarification.  In case 1, it seems that a marginal resection of the mandible was performed. Indication for a microvascular flap in absence of a segmental resection should be clarified.

• Introduction revision
• The use of bicortical DCIA flap when large amounts of bone segments must be harvested can sometimes cause abnormal hip contour, hernia, a tendency to severe bleeding, and gait disturbances[7]. Monocortical DCIA flaps can reduce donor-site morbidity for harvesting large amounts of bone segments [7]. In addition, the monocortical DCIA flap has the advantage of minimizing gait disturbance, preserving the contour of the contour of the hip, and speeding the patient`s postoperative recovery[7].   Monocortical DCIA flap can be used to reduce this complication, this method has advantages as a way of preserving hip contour and reducing the gait disturbance[7]

In the Discussion, the first paragraph seems to discuss the disadvantages of using plates instead of bone flaps but it again is poorly expressed in the English version and irrelevant in my opinion for the  purpose of the article. Also on page 9, the Paragraph "However these methods also have some limitations...........risk of re-fracture due to space between surrounding bones and implants" is totally unclear. What methods are they referring to? .

• Disccusion revision

There is a disadvantage in that the plate is fractured and exposed when using the a reconstruction plate and soft tissue are used for reconstruction in a long-term prognosis. In addition, reconstruction using plates has some limitations. It cannot be used for complex defects such as defects involving soft tissue and hard tissue[5]. In these cases, the hard tissue and additional soft tissue must be operated simultaneously. The oral cavity has a variety of masticatory muscles and facial expression muscles, and moves to perform various functions such as emotional expression, mastication, or pronunciation. For this reason, when oral defects are directly reconstructed with plate, various complications may occur, such as plate exposure, infection, and loosening of the fixing screw[5]. Also, it is hard to recover masticatory function when reconstructed using a reconstruction plate[5]. On the other hand, the osseous-free flap achieved long-term survival through normal bone remodeling by osseointegration with the existing bone tissue within 2~3 months. [25]. Reconstruction using free vasculaized flaps provides an environment similar to normal oral tissue that changes naturally with surrounding bone tissue, enabling remodeling of occlusion using implant placement, bone grafting, removal, and replanting[5]. Therefore, vascularized free flaps using hard and soft tissues are mainly used, and the use of reconstruction plates is becoming a secondary option[5].

• Removal of the sentences
• Recently, direct reconstruction of the maxillofacial defect using customized 3D-printed implants based on medical data and 3D printing techniques has been performed[23]. These methods report satisfactory results and can reduce the need for additional surgery such as a free flap. In addition, there is an advantage that it is not necessary to consider the morbidity of donor sites such as gait disturbance. These methods can prevent the possibility of postoperative complications.

However, these methods also have some limitations. First, when reconstructing both hard and soft tissues at the same time, additional surgery may be required to cover soft tissues. Second, when infection of the titanium implant occurs, it can spread to infection of the entire implant. This may require the removal of the entire implant. In addition, if titanium mesh larger or smaller than the bone defect area is used in open reduction surgery, there may be complications such as screw loosening, excessive tension in soft tissue, exposure to mesh, and risk of re-fracture due to space between surrounding bones and implants

Finally, they propose an open reduction with a patient-specific 3D-printed titanium implant for the iliac fracture fixation. The references concerning the use of this method either in the introduction or in the discussion are weak and the use of this treatment method for the referred iliac fractures needs a deeper discussion including other alternatives especially the possibility of conservative non-surgical treatment. Did the authors have other cases with this type of complication treated in a different way? 

• Introduction revision
• Generally, iliac bone fracture can be treated by open reduction and internal fixation. Orthopedic implants need to possess important properties such as biocompatibility, relevant mechanical properties, high corrosion and wear resistance, and osseointegration to ensure safe and effective use[8]. A variety of implant materials has been used according to requirements in various fields of medicine such as metals, alloys, ceramics, and polymers[8]. Among them, titanium and titanium alloys are widely used as orthopedic implant materials due to its mechanical and biological properties[9-13]. Moreover, porous titanium structure allows bone ingrowth into the porous to gain stable osseointegration between the implant and surrounding bones[14,15]. Recently, computer aided and 3D printed guided surgery is popular. So that, iliac bone fracture can treat with this modality. The introduction of Computer Aided Design (CAD) and Computer Aided Manufacturing (CAM) systems led to several advantages for both clinicians and patients, and commercial software are reliable methods to simulate and perform the procedure[16]. Titanium alloy orthopedic implants produced by 3D printing have the advantage of being able to manufacture complex structures that cannot be manufactured by traditional techniques and maintaining the excellent physicochemical properties of titanium and its alloys[17]. Using these techniques, surgeons can manufacture implants with excellent mechanical and biological properties in the exact shape and size they desired.

Author Response File: Author Response.docx

Reviewer 2 Report

The paper shows a very interesting usage of additive manufacturing in medical applications. Unfortunately, in the present form, the manuscript suffers from many major issues, which I listed below: 

1. The should not be abbreviations in the title (DCIA). Additionally, when you put an abbreviation, you should put the full description first and then provide its abbreviation i.e.: Deep circumflex iliac artery (DCIA) - make it the same in the whole manuscript, because in the case of ASIS you made it wrong. 

2. The abstract needs to be significantly improved. It has to provide information about the scope of your research, its novelty, and most important outcomes. You have 3d printed titanium in the title, but there is a lack of any information about it in the abstract. 

3. Please make the correction on the proper template file with numbered lines - now it is very hard to make a review. 

4. 3D printing is a colloquial name for additive manufacturing. Please use more academic language, also you should provide the more detailed name of used titanium alloy (i.e. Ti6Al4V)

5. The introduction needs to be significantly improved. You should make a deep review of using additive manufacturing (mostly titanium-based alloys) in medicine. 8 citations are a very poor review, especially, since there is a lot of available research related to the usage of titanium alloys in medical applications. You should analyze what other researchers made, and based on such review - you should formulate the main aim of your research and highlight its novelty. 

6. There is a lack of any information about the additive manufacturing process during your research. Please provide the whole chapter about the process with a detailed description of the used material, machine, postprocessing, etc. 

7. Please create an additional chapter with a conclusion and put them point-by-point. Now it is very hard to read. 

Author Response

Dear Reviewer

Thank you for your kind review

I tried to revise the manuscript according to your comment

Sincerely.

 

The paper shows a very interesting usage of additive manufacturing in medical applications. Unfortunately, in the present form, the manuscript suffers from many major issues, which I listed below: 

1. The should not be abbreviations in the title (DCIA). Additionally, when you put an abbreviation, you should put the full description first and then provide its abbreviation i.e.: Deep circumflex iliac artery (DCIA) - make it the same in the whole manuscript, because in the case of ASIS you made it wrong. 

- In Abstract, “ASIS (anterior superior iliac spine) -> anterior superior iliac spine(ASIS)”

2. The abstract needs to be significantly improved. It has to provide information about the scope of your research, its novelty, and most important outcomes. You have 3d printed titanium in the title, but there is a lack of any information about it in the abstract. 

Abstract: Jaw defect can have a variety of causes including tumors, trauma, and osteomyelitis. The reconstruction of jaw defects has been improved with free flaps technique and sophisticated microvascular techniques. Deep circumflex iliac artery (DCIA) flap provides a large amount of bone for the reconstructions of the mandible. However, various complications and side effects such as abnormal hip contour, hernia, severe bleeding tendency, gait disturbance, and hypoesthesia occurred. Iliac bone fracture is not common complication after DCIA flap harvesting, because anterior superior iliac spien(ASIS) (anterior superior iliac spine) can include the harvested flap. However, when include the ASIS, the patient might be lost the hip contour and suffered the gait disturbance. If iliac avulsion fracture occurs, various treatment options exist. If severe dislocation of the bone fragment exists, open reduction and internal fixation are required. At this time, orthopedic implants made of various materials can be used. Among them, when using a 3D fabricated implant using a titanium alloy, the accuracy of size and shape is excellent, and it can have mechanical-biocompatible advantages. In this study, we report cases of iliac bone fracture after reconstruction of the jaw with DCIA flap and the treatment modality using a 3D printed patient-specific titanium implant.

3. Please make the correction on the proper template file with numbered lines - now it is very hard to make a review. 레이아웃->줄번호 넣기
4. 3D printing is a colloquial name for additive manufacturing. Please use more academic language, also you should provide the more detailed name of used titanium alloy (i.e. Ti6Al4V)

- Titanium implant -> Ti6AL4V alloy implant

5. The introduction needs to be significantly improved. You should make a deep review of using additive manufacturing (mostly titanium-based alloys) in medicine. 8 citations are a very poor review, especially, since there is a lot of available research related to the usage of titanium alloys in medical applications. You should analyze what other researchers made, and based on such review - you should formulate the main aim of your research and highlight its novelty. 

Generally, iliac bone fracture can be treated by open reduction and internal fixation. Orthopedic implants need to possess important properties such as biocompatibility, relevant mechanical properties, high corrosion and wear resistance, and osseointegration to ensure safe and effective use[8]. A variety of implant materials has been used according to requirements in various fields of medicine such as metals, alloys, ceramics, and polymers[8]. Among them, titanium and titanium alloys are widely used as orthopedic implant materials due to its mechanical and biological properties[9-13]. Moreover, porous titanium structure allows bone ingrowth into the porous to gain stable osseointegration between the implant and surrounding bones[14,15]. Recently, computer aided and 3D printed guided surgery is popular. So that, iliac bone fracture can treat with this modality. The introduction of Computer Aided Design (CAD) and Computer Aided Manufacturing (CAM) systems led to several advantages for both clinicians and patients, and commercial software are reliable methods to simulate and perform the procedure[16]. Titanium alloy orthopedic implants produced by 3D printing have the advantage of being able to manufacture complex structures that cannot be manufactured by traditional techniques and maintaining the excellent physicochemical properties of titanium and its alloys[17]. Using these techniques, surgeons can manufacture implants with excellent mechanical and biological properties in the exact shape and size they desired.

Citations revision

8. KAUR, Manmeet; SINGH, K. Review on titanium and titanium based alloys as biomaterials for orthopaedic applications. Materials Science and Engineering: C, 2019, 102: 844-862.
9. THELEN, Sarah; BARTHELAT, François; BRINSON, L. Catherine. Mechanics considerations for microporous titanium as an orthopedic implant material. Journal of Biomedical Materials Research Part A: An Official Journal of The Society for Biomaterials, The Japanese Society for Biomaterials, and The Australian Society for Biomaterials and the Korean Society for Biomaterials, 2004, 69.4: 601-610.
10. ALBREKTSSON, Tomas, et al. The interface zone of inorganic implantsIn vivo: Titanium implants in bone. Annals of biomedical engineering, 1983, 11.1: 1-27.
11. HAYASHI, K., et al. Quantitative analysis of in vivo tissue responses to titanium‐oxide‐and hydroxyapatite‐coated titanium alloy. Journal of biomedical materials research, 1991, 25.4: 515-523.
12. LAING, Patrick G.; FERGUSON JR, Albert B.; HODGE, Edwin S. Tissue reaction in rabbit muscle exposed to metallic implants. Journal of Biomedical Materials Research, 1967, 1.1: 135-149.
13. LONG, Marc; RACK, H. J. Titanium alloys in total joint replacement—a materials science perspective. Biomaterials, 1998, 19.18: 1621-1639.
14. CHANG, Yong-Shun, et al. Significance of interstitial bone ingrowth under load-bearing conditions: a comparison between solid and porous implant materials. Biomaterials, 1996, 17.11: 1141-1148.
15. SPOERKE, Erik D., et al. A bioactive titanium foam scaffold for bone repair. Acta Biomaterialia, 2005, 1.5: 523-533.
16. Pagano, S.; Moretti, M.; Marsili, R.; Ricci, A.; Barraco, G.; Cianetti, S. Evaluation of the accuracy of four digital methods by linear and volumetric analysis of dental impressions. Materials 2019, 12, 1958.
17. JING, Zehao, et al. Functionalization of 3D-printed titanium alloy orthopedic implants: A literature review. Biomedical Materials, 2020, 15.5: 052003.

 

6. There is a lack of any information about the additive manufacturing process during your research. Please provide the whole chapter about the process with a detailed description of the used material, machine, postprocessing, etc. 

-2. Case presentation revision

For computer-assisted surgery, CT data of the patient's pre-surgical ilium and fractured ilium were collected. The collected CT data were saved as a DICOM file and superimposed into an ilium using Mimics software 18.0 (Materialize, Leuven, Belgium). After setting the threshold value based on the bone HU value, performed 2D masking. Segment separation in the ROI area and artifact removal were performed, and 2D masking is laminated to produce a 3D shape. Created natural bone shape through smoothing work. Reconstruct the defect area using CT data of the patient before fracture, and apply the porous structure of the inside and design the fixation part. Using electron beam melting(EBM) technique, a high-energy electron beam was exposed inside the vacuum chamber to melt metal powder(Ti6Al4V alloy powder) and print the final implant(Q10 Plus,GE Additive). Sanding to remove the powder of the final printed implant and removal of the support of the printed implant were carried out. A customized implant for reduction was designed using the original shape of the ilium. The Ti6Al4V alloy implant reproduces the shape of the natural ilium while the interior is porous to improve cell proliferation and mesenchymal stem cell differentiation. On the outer surface, a plate shape with a hole for fixation with iliac bone was added(Figure 2).

7. Please create an additional chapter with a conclusion and put them point-by-point. Now it is very hard to read. 

- Revision the conclusion

5. Conclusion

 Reconstruction of a fractured donor site using the 3D fabricated implant has the following advantages.

First, because it is fabricated based on the shape before fracture, it is possible to restore the shape of the patient`s normal Iliac bone.

Second, the operation time could be shortened by omitting the additional correction of the shape of the implant or fractured bone.

Third, the porous structure could shorten the recovery period after surgery.

When using the preoperative CT data to manage the postoperative fracture and reconstruct the defect using titanium mesh can be a useful method to accurately reduce the fracture and reconstruct the defect at the same time. In addition, in this method, in conventional fracture surgery, preoperative CT could be used to perform reduction through computer-aided simulation and fabricated a suitable plate of the reduced bone by 3D printing and then the plates and guides can be used during the surgery.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The manuscript has been significantly improved, but there are still some issues: 

1. Points 3 and 4 of my review still were not included (lack of lines numeration, in the title there is still 3D Print instead of Additive Manufacturing. 

2. Conclusion part could be more specific. What were the main outcomes of your paper? Did everything was properly made? Maybe there are some parts of your work that could be a base for some further research? Please read the instruction for authors - there will be all data about the proper form of the conclusion part.  

Author Response

Dear Reviewer

Thank you for your kind review

We tried to revise the manuscript according to your comment

Sincerely.

 1. Points 3 and 4 of my review still were not included (lack of lines numeration, in the title there is still 3D Print instead of Additive Manufacturing.

 - revised the title and manuscript

 - Title: Fixation of iliac avulsion fracture using additive manufacturing titanium mesh after DCIA flap

2. Conclusion part could be more specific. What were the main outcomes of your paper? Did everything was properly made? Maybe there are some parts of your work that could be a base for some further research? Please read the instruction for authors - there will be all data about the proper form of the conclusion part.

 - Conclusion was revised as followings

 - Conclusion

In conclusion, patient-specific titanium implant is possible to restore the shape of the patient’s normal iliac bone and the bone is reduced to its original shape, no additional force is applied to the surrounding soft tissue in jaw reconstruction patients. When using the preoperative CT data to manage the postoperative fracture and reconstruct the defect, patient-specific titanium implant can be a useful tool to accurately reduce the fracture and reconstruct the defect at the same time. In addition, when using this method in conventional fracture surgery, preoperative CT could be used to perform reduction through a computer-aided simulation, and we could fabricate a suitable plate of the reduced bone by additive manufacturing; then, the plates and guides could be used during the surgery.

Author Response File: Author Response.docx