Review Reports - Long-Term Survival of a Custom 3D-Printed Implant in a Patient with a Massive Acetabular Defect: A 10-Year Follow-Up—From Mistakes to Useful Experience

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

1. The clinical timeline should be presented more clearly and consistently.
The patient underwent several major procedures within a relatively short period, including constrained liner revision in June 2015, Müller cage reconstruction in January 2016, custom 3D-printed reconstruction in March 2016, and dual-mobility revision in 2025. A concise timeline summarizing the indication, acetabular defect classification, implant used, reason for failure, and clinical outcome of each procedure would substantially improve readability. This is particularly important because the manuscript aims to demonstrate the evolution of management over a 10-year period. The SCARE 2023 guideline also specifically recommends presenting the sequence of clinical events clearly.

2. The progression of the acetabular defect from Paprosky IIIA to IIIB requires stronger objective documentation.
The authors state that the defect progressed from Paprosky IIIA to IIIB and suggest that mechanical stress associated with the combination of a constrained liner and cage contributed to progressive osteolysis. However, this causal interpretation appears stronger than can be established from a single case. The authors should provide clearer radiographic or CT evidence supporting the change in Paprosky classification and distinguish documented findings from their proposed mechanism of failure.

3. More technical information regarding the custom 3D-printed implant is needed.
Since the principal value of this report is the 10-year survival of a custom implant, additional information regarding implant design and reconstruction would strengthen the manuscript. The authors currently describe CT-based planning, trabecular titanium, customized support zones, and screw fixation into pelvic safe zones. However, details regarding implant manufacturing, porous structure, fixation strategy, number and location of screws, planned versus achieved implant position, and criteria used to evaluate osseointegration would improve reproducibility and clinical relevance.

4. The long-term clinical outcome should be reported more quantitatively.
The manuscript states that the HHS improved from <70 preoperatively to a good postoperative result, and later reports a final HHS of 85. However, serial HHS values and the exact timing of these assessments are not provided. Given the 10-year follow-up, functional outcomes at clinically meaningful intervals (e.g., 1, 5, and 10 years), if available, would be much more informative. Similarly, pain, walking ability, assistive-device use, and patient satisfaction should be reported when available.

5. The 2025 dislocation deserves a more detailed analysis.
The authors attribute the late instability to abductor mechanism insufficiency rather than failure of the custom acetabular component. This distinction is important and represents one of the most educational aspects of the case. However, objective evidence supporting abductor deficiency should be provided. The authors should clarify how abductor insufficiency was diagnosed and whether imaging or intraoperative findings demonstrated loss of gluteus medius/minimus attachment. In addition, the rationale for choosing dual mobility rather than another constrained construct should be explained more directly in relation to this patient's specific anatomy and soft-tissue deficiency.

6. A dedicated limitations section should be added and the conclusions should be moderated.
This is a single case and therefore cannot establish the general effectiveness or predictability of custom 3D-printed implants. Statements such as these implants being an “effective method” providing “predictable long-term results” appear stronger than the evidence provided by this report. The conclusions should emphasize that this case demonstrates the feasibility and potential durability of this reconstruction strategy rather than establishing its effectiveness. A separate limitations paragraph would also improve compliance with SCARE 2023, which specifically requests reporting of the strengths and limitations of surgical case reports.

Author Response

Dear Reviewer, thank you for your attention to our work and for the comments that helped us strengthen it. Below are the revisions made in accordance with your comments.

Comment 1. The clinical timeline should be presented more clearly and consistently.

Response 1 Thank you for your comment. To specify the dates more precisely, we consulted the patient's medical records; the dates in the manuscript text are now specified down to the exact day (e.g., "2.1. Patient's initial presentation (23/05/2015)").

Comment 2. The progression of the acetabular defect from Paprosky IIIA to IIIB requires stronger objective documentation.

Response 2. Thank you for your comment. The authors have removed the statement regarding the specific theory of osteolysis onset in this case from the manuscript, retaining only the statement concerning the general biochemical mechanism of osteolysis development. To document the progression of the defect, Figure 5—showing a 3D reconstruction of the patient's damaged acetabulum—has been included in Section 2.5.

Comment 3: More technical information regarding the custom 3D-printed implant is needed.

Response 3: Thank you for your comments. Greater details about the implant and its installation have been added to the text of the manuscript "To support osteoinduction and osteoconduction, the implant surface facing the acetabular bone featured a hydroxyapatite coating. Additionally, the inner surface of the implant was smooth but contained numerous recesses to facilitate the penetration and fixation of the bone cement intended for the implantation of the endoprosthesis cup." "The implant was secured according to the preoperative plan using eight 6.5 mm diameter screws. Five screws were inserted into the ilium in an anterior-to-posterior sequence, with lengths of 35, 40, 40, 45, and 50 mm. Two 40 mm screws were inserted into the ischium. One 45 mm screw was inserted into the superior pubic ramus." «Given the initial rollout of these implants in the country and our clinic's first experience with their placement, the manufacturer did not provide test plastic models that would have allowed for a manual assessment of implant positioning during the pre-operative stage. This factor significantly influenced the duration of the surgical procedure.»

Comment 4: The long-term clinical outcome should be reported more quantitatively.

Response 4: Thank you for your comments. Clarifications have been added to the manuscript text : «Following the surgical procedure and implant placement, the patient underwent outpatient monitoring over an eight-year period, with assessments conducted at one-year intervals. Significant functional results were noted one year post-surgery (May 2017), with an HHS score of 84, indicating a good outcome. By this time, the patient reported no joint pain at rest (VAS score: 0), although she experienced minor discomfort in the groin area on the operated side during movement (VAS score: up to 2). After four years of regular follow-up, a subsequent outpatient visit revealed significant functional improvement—an HHS score of 89—with a complete absence of pain both at rest and during movement (VAS score: 0). No further significant improvements in functional outcome were observed after this period.»

Comment 5: The 2025 dislocation deserves a more detailed analysis.

Response 5 : Thank you for your comments. Added to the text of the manuscript: . Therefore, in 2025, the patient underwent implantation of a dual-mobility device aimed at additional joint stabilization by increasing the safe range of motion and re-ducing the risk of dislocation due to abductor deficiency (Figure 8). Abductor insuffi-ciency was associated with pre-existing osteolysis of the greater trochanter—which progressed during the postoperative period—as well as recurrent injury and fibrous degeneration of the gluteal muscles. These factors led to implant instability, resulting in dislocation. Currently, the established standard of care for this category of patients is the implantation of a dual-mobility system. [13,18–22]. The cemented endoprosthesis cup was removed by sequentially drilling it out with circular burrs until the intact cement mantle was visualized. A dual-mobility cement-ed cup was implanted using the cement-on-cement technique, with the insertion of a polyethylene liner and a 28 mm head.

Comment 6: A dedicated limitations section should be added and the conclusions should be moderated.

Response 6: Thank you for your comments. Changes have been made to the text of the manuscript, a section has been added: Limitations of the study

The authors highlight several significant limitations of this case report. A primary drawback is the absence of documentation regarding the manufacturers of the im-plants placed in the patient prior to 2016. Such information could have enriched the case description and provided greater clarity by detailing the specific characteristics of the individual endoprosthesis components from those manufacturers.

Another limitation is the lack of clear digital radiographs from the period prior to 2016, a result of the digital infrastructure arrangements for medical care in the region where the authors practiced at the time. Poor image clarity may affect the assessment of the severity of acetabular and proximal femoral defects.

Furthermore, a significant limitation is the lack of a clear explanation for the dis-crepancy between the favorable functional outcome last recorded (89 points) and the concurrently progressing abductor deficit that led to joint instability. The authors attribute this inconsistency primarily to the patient's subjective perception of joint function, driven by her personal satisfaction with the su

Reviewer 2 Report

Comments and Suggestions for Authors

Thank you for the opportunity to review this manuscript. The authors report a case of a massive acetabular defect treated with a custom-made 3D-printed implant with approximately 10 years of follow-up. Although this is a difficult and interesting case, I have serious concerns regarding the novelty of this report.

The main concern is the lack of novelty. Custom-made 3D-printed/triflange acetabular components for massive acetabular defects, including Paprosky IIIB defects, have already been reported in many studies. Long-term results of more than 10 years have also been published, including the studies cited by the authors themselves. Therefore, it is unclear what new clinical information can be obtained from this single case. The use of dual mobility for recurrent instability is also not a new treatment strategy. The authors should clearly explain what is novel or unique in this case compared with previous reports. There are also several important problems with the case presentation.

・Basic patient information is missing. Please provide the patient's age, original diagnosis of the hip, date of primary THA, and detailed surgical history.

・The cause of the recurrent dislocation is unclear. Why did the authors consider the hip unstable, and why was a constrained liner selected? Component position, impingement, abductor function, and soft-tissue deficiency should be described. In Figure 1, there already seems to be substantial bone loss around the greater trochanter, which may be related to the instability.

・The Case Presentation contains too much discussion and literature review. This section should mainly describe the clinical course. Discussion of previous studies should be moved to the Discussion section.

・The progression of failure is not sufficiently documented. Please provide a radiograph showing the failure of the Müller cage before the custom-made reconstruction. In addition, the authors describe the loosening as “aseptic,” but it is unclear how infection was excluded. The reason for such rapid progression of osteolysis within approximately six months is also unclear. The causal relationship between the constrained liner and osteolysis appears speculative.

・More detailed information regarding the custom-made 3D-printed implant is necessary. The manuscript only describes the material as “trabecular titanium.” Please clarify whether the implant was made of commercially pure titanium or a titanium alloy. If a titanium alloy was used, its composition or material specification should be provided. The manufacturing process should also be described in sufficient detail, including the manufacturer of the 3D printer, model of the printer, printing technique, and other relevant manufacturing parameters.

・Some outcome statements are not sufficiently supported. The authors state that the limb-length discrepancy was corrected, but Figure 8 appears to show that the right lower extremity is longer than the left. Objective measurement should be provided.

・The follow-up after the dual-mobility revision is unclear. The authors state that hip stability was achieved, but the duration of follow-up after the 2025 surgery is not reported. A short follow-up period is not sufficient to conclude that recurrent instability was successfully treated.

・HHS should be presented as exact values, not as ranges such as “<70” or “80–89.” The timing of each HHS assessment should also be clearly stated.

The major concern is the lack of sufficient novelty. Long-term outcomes of custom-made acetabular implants have already been reported, and I could not identify a sufficiently new clinical message from this case. In addition, several important clinical and technical details are missing. These problems substantially limit the scientific value of this report. Therefore, I recommend rejection.

Author Response

Dear Reviewer, thank you for your attention to our work and for the comments that helped us strengthen it. Below are the revisions made in accordance with your comments.

Comment 1. Basic patient information is missing. Please provide the patient's age, original diagnosis of the hip, date of primary THA, and detailed surgical history.

Response 1 Thank you for your comment. We have added the key information known to us to the text: "Patient S. (aged 64 at the time of presentation in 2015; body mass index 28.4) presented with complaints of severe instability of her right hip joint, accompanied by recurrent dislocations and impaired weight-bearing ability. Her medical history included total hip replacement of the right hip in 2010. In the previous year, five episodes of hip replacement dislocation had been recorded, indicating chronic joint instability and the need for revision surgery."

However, we do not have precise data regarding the characteristics of the arthroplasty performed prior to our involvement, due to the lack of surviving documentation.

Comment 2. The cause of the recurrent dislocation is unclear. Why did the authors consider the hip unstable, and why was a constrained liner selected? Component position, impingement, abductor function, and soft-tissue deficiency should be described. In Figure 1, there already seems to be substantial bone loss around the greater trochanter, which may be related to the instability

Response 2. Thank you for your comments. Added to the text of the manuscript: "The authors attributed the recurrent dislocations present at the time of the patient's hospitalization to progressive abductor instability associated with progressive osteoly-sis of the greater trochanter" "This extent of surgical intervention was necessitated by the lack of alternatives (such as dual-mobility implants) and recurrent dislocations observed during intraoperative stress testing (deep hip flexion resulted in posterior dislocation)."

Comment 3: The Case Presentation contains too much discussion and literature review. This section should mainly describe the clinical course. Discussion of previous studies should be moved to the Discussion section.

Response 3: Thank you for the comment. The elements of the literature review have been condensed.

Comment 4: The progression of failure is not sufficiently documented. Please provide a radiograph showing the failure of the Müller cage before the custom-made reconstruction. In addition, the authors describe the loosening as “aseptic,” but it is unclear how infection was excluded. The reason for such rapid progression of osteolysis within approximately six months is also unclear. The causal relationship between the constrained liner and osteolysis appears speculative.

Response 4: Thank you for your comment. amendments have been made to emphasize the subjectivity of the authors' opinions: In the opinion of the team of authors, the combination of the cage with the constrained liner created conditions for additional mechanical stress: the limited range of motion of the liner led to repeated impingement, and the transfer of increased loads through the rigid structure of the cage to the weakened bone tissue aggravated the process of osteolysis.»

Unfortunately, the radiograph of the defect has been preserved only in the form shown in Figure 5. Archival photo taken prior to a revision surgery involving the placement of a 3D implant in the patient.

Comment 5 More detailed information regarding the custom-made 3D-printed implant is necessary.

Response 5 Thank you for your comments. Clarifications have been added to the text: «The implant was manufactured by the Russian company "LOGEEKS MS" in accordance with Certificate of Conformity No. RUHE06.H18644. The material used is titanium. The printing technology employed is Selective Laser Melting, in which a laser fuses titanium powder layer by layer to create precise copies of modeled 3D structures. The layer thickness ranges from 20 to 200 µm.»

"Patient S. (aged 64 at the time of presentation in 2015; body mass index 28.4) presented with complaints of severe instability of her right hip joint, accompanied by recurrent dislocations and impaired weight-bearing ability. Her medical history included total hip replacement of the right hip. In the previous year, five episodes of hip replacement dislocation had been recorded, indicating chronic joint instability and the need for revision surgery." Unfortunately, we do not have documented data regarding the patient's chronic medical conditions. Full details regarding the implant characteristics have been included: "Intraoperative placement of the custom acetabular implant was completely satisfactory: precise conformity with the defect's anatomy, complete replacement, and reliable primary stability of the structure were achieved. The implant was secured according to the preoperative plan using eight 6.5 mm diameter screws. Five screws were inserted into the ilium in an anterior-to-posterior sequence, with lengths of 35, 40, 40, 45, and 50 mm. Screws inserted through the implant's superior flange (35 and 40 mm) were placed bicortically, while the remaining screws were inserted monocortically from the inner aspect. Two 40 mm screws were bicortically inserted into the ischium. One 45 mm screw was inserted into the superior pubic ramus. Following placement of the custom acetabular component, the cemented cup (Marathon™, DePuy Synthes) with a diameter of 52 mm was installed; the need for a constrained liner was eliminated due to restoration of joint stability. Primary stability of the structure was achieved intraoperatively, with no signs of dislocation."

Comment 6: outcome statements are not sufficiently supported. The authors state that the limb-length discrepancy was corrected, but Figure 8 appears to show that the right lower extremity is longer than the left. Objective measurement should be provided.

Response 6: Unfortunately, we are currently unable to invite the patient for an outpatient appointment; therefore, the statement regarding limb length has been removed from the text.

Comments 7 and 8: The follow-up after the dual-mobility revision is unclear. The authors state that hip stability was achieved, but the duration of follow-up after the 2025 surgery is not reported. A short follow-up period is not sufficient to conclude that recurrent instability was successfully treated.

・HHS should be presented as exact values, not as ranges such as “<70” or “80–89.” The timing of each HHS assessment should also be clearly stated.

Response : Functional outcomes were assessed using the Harris Hip Score (HHS). Preoperatively (03/2016), scores were unsatisfactory (67 points), reflecting severe pain (6 points at rest and 7 upon joint movement on the Visual Analog Scale (VAS) for pain) and significant functional limitations. Following the surgical procedure and implant placement, the patient underwent outpatient monitoring over an eight-year period, with assessments conducted at one-year intervals. Significant functional results were noted one year post-surgery (May 2017), with an HHS score of 84, indicating a good outcome. By this time, the patient reported no joint pain at rest (VAS score: 0), although she experienced minor discomfort in the groin area on the operated side during movement (VAS score: up to 2). After four years of regular follow-up, a subsequent outpatient visit revealed significant functional improvement—an HHS score of 89—with a complete absence of pain both at rest and during movement (VAS score: 0). No further significant improvements in functional outcome were observed after this period [7–9,12].

Comment 9: outcome statements are not sufficiently supported. The authors state that the limb-length discrepancy was corrected, but Figure 8 appears to show that the right lower extremity is longer than the left. Objective measurement should be provided.

Response 9: Unfortunately, we are currently unable to invite the patient for an outpatient appointment; therefore, the statement regarding limb length has been removed from the text.

The authors are firmly convinced that this work would be highly relevant and instructive for young surgeons and worthy of publication in the journal. We made mistakes and learned from them; we have a duty to share these experiences so that no one else repeats them.

Reviewer 3 Report

Comments and Suggestions for Authors 1. Please briefly state whether the original custom 3D acetabular component was retained during the 2025 reoperation (dual-mobility insertion). If the cup was retained, the conclusion of stable acetabular fixation at 10 years is fully supported and this should be stated explicitly. It would also help to specify the exact date of the last follow-up and the total follow-up duration. 2. The defect is described as IIIA at the stage of osteolysis and IIIB later on. Please indicate the classification at each stage (in particular at the time of cage implantation in 01/2016 and at the time of 3D implant reconstruction in 03/2016), with the corresponding imaging basis, so that the timeline is easy to follow. 3. The two procedures were only about two months apart. A short sentence on the indication for early revision (e.g., progressive osteolysis, migration, or persistent symptoms), and confirmation that infection was excluded, would be helpful for readers. 4. The Introduction states that results were assessed using clinical, functional and imaging data, but no values are reported. 5. Please add: basic patient demographics (age, sex, BMI, comorbidities); key technical parameters of the implant (porosity, number and location of screws, use of bone graft); and removal of the remaining "FOR PEER REVIEW" watermark, placeholder dates and minor formatting/typographical errors.

Author Response

Dear Reviewer, thank you for your attention to our work and for the comments that helped us strengthen it. Below are the revisions made in accordance with your comments.

Comment 1. Please briefly state whether the original custom 3D acetabular component was retained during the 2025 reoperation (dual-mobility insertion).

Response 1 Thank you for your comment. Clarifications regarding this matter have been made to the text. «The cemented cup was removed by sequentially drilling it out with acetabulum reamers until the intact cement mantle was visualized. During this procedure, the integrity and stability of the custom implant were continuously monitored and fully preserved.» “Functional outcomes were assessed using the Harris Hip Score (HHS). Preoperatively (03/2016), scores were unsatisfactory (67 points), reflecting severe pain (6 points at rest and 7 upon joint movement on the Visual Analog Scale (VAS) for pain) and significant functional limitations. Following the surgical procedure and implant placement, the patient underwent outpatient monitoring over an eight-year period, with assessments conducted at one-year intervals. Significant functional results were noted one year post-surgery (May 2017), with an HHS score of 84, indicating a good outcome. By this time, the patient reported no joint pain at rest (VAS score: 0), although she experienced minor discomfort in the groin area on the operated side during movement (VAS score: up to 2). After four years of regular follow-up, a subsequent outpatient visit revealed significant functional improvement—an HHS score of 89—with a complete absence of pain both at rest and during movement (VAS score: 0). No further significant improvements in functional outcome were observed after this period [7–9,12].”

Comment 2. . The defect is described as IIIA at the stage of osteolysis and IIIB later on. Please indicate the classification at each stage

Response 2. Thank you for your comment. The text of the manuscript states “Control radiographs revealed signs of severe periprosthetic osteolysis and aseptic instability of the endoprosthesis components (Figure 3). According to CT scan data, the acetabular defect at this stage corresponds to Paprosky type IIIA.” followed by a logical progression in the text “Osteolysis progressed, with structural migration and loosening of the femoral component noted. As a result of multiple revision surgeries and ongoing osteolysis, a massive acetabular defect developed, involving the pelvic supporting columns, classi-fied as Paprosky IIIB." Paprosky IIIB represents the end-stage condition that led to the placement of a 3D-printed implant.

Comment 3: The two procedures were only about two months apart. A short sentence on the indication for early revision (e.g., progressive osteolysis, migration, or persistent symptoms), and confirmation that infection was excluded, would be helpful for readers

Response 3: Thank you for your comments. The manuscript states: "Osteolysis progressed, with structural migration and loosening of the femoral component noted. As a result of multiple revision surgeries and ongoing osteolysis, a massive acetabular defect developed, involving the pelvic supporting columns, classified as Paprosky IIIB." Additionally, new information has been added: "Periprosthetic joint infection was ruled out based on joint aspiration results and normal C-reactive protein levels and erythrocyte sedimentation rates throughout the postoperative period."

Comment 4: The Introduction states that results were assessed using clinical, functional and imaging data, but no values are reported

Response 4: You are absolutely right, this defect has been corrected: "Functional outcomes were assessed using the Harris Hip Score (HHS). Preopera-tively (03/2016), scores were unsatisfactory (67 points), reflecting severe pain (6 points at rest and 7 upon joint movement on the Visual Analog Scale (VAS) for pain) and significant functional limitations. Following the surgical procedure and implant placement-ment, the patient underwent outpatient monitoring over an eight-year period, with assessments conducted at one-year intervals. Significant functional results were noted one year post-surgery (May 2017), with an HHS score of 84, indicating a good out-come. By this time, the patient reported no joint pain at rest (VAS score: 0), although she experienced minor discomfort in the groin area on the side during movement (VAS score: up to 2) functional improvement—an HHS score of 89—with a complete absence of pain both at rest and during movement (VAS score: 0). No further significant improvements in functional outcome were observed after this period [7–9,12]."

Comment 5: Please add: basic patient demographics (age, sex, BMI, comorbidities); key technical parameters of the implant (porosity, number and location of screws, use of bone graft); and removal of the remaining "FOR PEER REVIEW" watermark, placeholder dates and minor formatting/typographical errors.

Response 5 Thank you for your comments. Clarifications have been added to the text: "Patient S. (aged 64 at the time of presentation in 2015; body mass index 28.4) presented with complaints of severe instability of her right hip joint, accompanied by recurrent dislocations and impaired weight-bearing ability. Her medical history included total hip replacement of the right hip. In the previous year, five episodes of hip replacement dislocation had been recorded, indicating chronic joint instability and the need for revision surgery." Unfortunately, we do not have documented data regarding the patient's chronic medical conditions. Full details regarding the implant characteristics have been included: "Intraoperative placement of the custom acetabular implant was completely satisfactory: precise conformity with the defect's anatomy, complete replacement, and reliable primary stability of the structure were achieved. The implant was secured according to the preoperative plan using eight 6.5 mm diameter screws. Five screws were inserted into the ilium in an anterior-to-posterior sequence, with lengths of 35, 40, 40, 45, and 50 mm. Screws inserted through the implant's superior flange (35 and 40 mm) were placed bicortically, while the remaining screws were inserted monocortically from the inner aspect. Two 40 mm screws were bicortically inserted into the ischium. One 45 mm screw was inserted into the superior pubic ramus. Following placement of the custom acetabular component, the cemented cup (Marathon™, DePuy Synthes) with a diameter of 52 mm was installed; the need for a constrained liner was eliminated due to restoration of joint stability. Primary stability of the structure was achieved intraoperatively, with no signs of dislocation."

Thank you for your comments. We do not distribute watermarks throughout the text; these are removed by the editors at a later stage should you approve the work for potential publication.Comment 6: A dedicated limitations section should be added and the conclusions should be moderated.

Response 6: Thank you for your comments. Changes have been made to the text of the manuscript, a section has been added: Limitations of the study

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Thank you for the authors’ careful revision. The manuscript has clearly improved in terms of the clinical description, surgical details, and presentation of functional outcomes. However, my principal concern in the previous review was not primarily the completeness of the case description, but rather the lack of novelty. I do not believe that this fundamental issue has been adequately addressed in the revised manuscript.

Custom-made 3D-printed/triflange acetabular components for massive acetabular defects, including Paprosky IIIB defects, have already been extensively reported. Importantly, long-term results exceeding 10 years have also been published, and several such studies are cited in the revised manuscript itself. The authors refer to previous reports demonstrating long-term radiographic stability and implant retention of custom triflange components. surgeries-4539313-peer-review-v2 Therefore, long-term survival of a custom-made acetabular implant in a single patient does not, by itself, appear to provide sufficiently new clinical information.

Similarly, the use of dual-mobility components for recurrent instability, particularly in the setting of abductor insufficiency, is already an established treatment strategy. Although the clinical course of this patient is complicated and may have educational value, it remains unclear what novel treatment concept, technical innovation, or previously unreported clinical finding this case adds to the existing literature.

In addition, several issues remain unresolved. The follow-up duration after the dual-mobility revision in May 2025 is still unclear, making the statement that recurrent instability was successfully treated difficult to support. The authors should also report the diameter of the mobile polyethylene outer bearing, as this is an important parameter related to effective head size and stability in a dual-mobility construct.

The response letter states that the claim regarding correction of limb-length discrepancy was removed because objective assessment was unavailable; however, the revised manuscript still states that limb length was equalized. In addition, the custom implant material is described only as “titanium,” without clarification of whether commercially pure titanium or a titanium alloy was used, and the 3D-printer manufacturer/model remains unspecified.

Overall, I appreciate the authors’ efforts to improve the manuscript. However, these revisions mainly improve the completeness of the case description and do not resolve my principal concern regarding novelty. Custom 3D-printed acetabular reconstruction for Paprosky IIIB defects, long-term implant survival, and the use of dual mobility for recurrent instability have all been previously reported.

Therefore, despite the improvements, I do not believe that this case provides sufficient novel clinical information to justify publication, and I cannot recommend publication.

Author Response

Comment 1: “The follow-up duration after the dual-mobility revision in May 2025 is still unclear, making the statement that recurrent instability was successfully treated difficult to support”

Reply 1: Thank you for your comments. The text contains clarifications on dynamic monitoring of the patient's condition: “The patient was followed up on an outpatient basis at intervals of 1, 3, 6, and 12 months postoperatively. The late postoperative course has been uneventful; as of the time of writing this case report and the patient's most recent outpatient visit at our request (September 4, 2026), the patient reports no active complaints regarding the operated hip joint." and “At the time of the outpatient follow-up in September 2026, joint function assessed via the HHS was 89, with no pain during active or passive joint movements (VAS score: 0). The authors are continuing active dynamic monitoring of the patient's condition."

Comment 2: “The authors should also report the diameter of the mobile polyethylene outer bearing, as this is an important parameter related to effective head size and stability in a dual-mobility construct.”

Answer 2: Thank you for your comments. The text contains the necessary clarifications on the installed implants: “A dual-mobility cemented cup with 51 mm. diameter (Capitole®, Evolutis Group) was implanted using the cement-on-cement technique, with the insertion of a 51 mm diameter polyethylene liner (UHMWPE®, Evolutis Group) and a 28 mm. head."

Comment 3: “The response letter states that the claim correction regarding limb-length discrepancy was removed because objective assessment was unavailable”
Answer 3: Thank you for your note, however, the statement about the length of the limb was removed by us and highlighted by the editors with a red marker with the text crossed out as deleted material, for greater clarity of the amendments made in the previous edition of the manuscript “Particular attention was paid to restoring the biomechanics of the hip joint. Intraoperatively, anatomically correct restoration of the joint's center of rotation was achieved, as well as elimination of limb shortening, leading to equalization of the lower limb length and an improved gait pattern."

Comment 4: “In addition, the custom implant material is described only as “titanium,” without clarification of whether commercially pure titanium or a titanium alloy was used, and the 3D-printer manufacturer/model remains unspecified.”
Answer 4: Thank you for your comment. The authors contacted the manufacturer of the custom implant, obtained the necessary information, and incorporated it into the text: "The material used is Ti6Al4V titanium alloy (UNS R56400), compliant with the international standard ISO 5832-3:2021. The printing technology employed is Selective Laser Melting using a specialized EOS M290 3D printer, in which a laser fuses titanium alloy powder layer by layer to create precise copies of modeled 3D structures."
Comment 5: “However, these revisions mainly improve the completeness of the case description and do not resolve my principal concern regarding novelty.”
Answer 5: The authors are sincerely grateful for the comments, which significantly helped strengthen our article. We would like to emphasize once again that this publication illustrates the evolution of perspectives on the use of 3D-printed implants, drawing on the experience of our country within the context of global practice. Not all of the journal's readers work in clinics that utilize personalized technologies; this material will be of particular interest to young physicians and—importantly—to a broad range of specialists seeking to stay abreast of the latest advancements in orthopedics.
Added “Conclusion
Custom 3D-printed implants represent an effective and rapidly evolving method for reconstructing extensive defects of the acetabulum and bone in general. The authors believe that the experience, mistakes, and solutions presented in the manuscript will serve as a valuable example for young orthopedic surgeons when selecting optimal treatment strategies for patients with extensive bone defects. Furthermore, the authors sincerely believe that this work will also be of interest to physicians in other specialties, as it sheds light on the long and arduous journey these patients undertake to regain a normal quality of life.”

Round 3

Reviewer 2 Report

Comments and Suggestions for Authors

Thank you for revising the manuscript again.

The manuscript became clearer, and several technical points were improved. However, my main concern has not changed from my first review. The main problem is the lack of novelty.

Custom-made 3D-printed acetabular components for massive acetabular defects, including Paprosky IIIB defects, have already been reported in many previous studies. Long-term results over 10 years have also already been published. In fact, several such studies are cited in this revised manuscript itself. Therefore, I do not think that 10-year survival of a custom-made acetabular implant in one patient provides new clinical information. surgeries-4539313-peer-review-v3

Also, the use of dual-mobility components for recurrent instability and abductor insufficiency is already a well-known treatment option. In this case, the custom implant was preserved and a dual-mobility system was used for late instability. This may be useful as a clinical experience, but I do not think this is a new treatment concept or new surgical technique. surgeries-4539313-peer-review-v3

I understand the authors’ opinion that this case may be educational, especially for young orthopedic surgeons. However, educational value and novelty are different points. The authors explain that this experience may be useful for young surgeons and for doctors who are not familiar with personalized implants, but this does not clearly show what new clinical knowledge this case adds to the previous literature. Author comment2

The authors have now corrected many of the detailed points raised in the previous reviews. However, these revisions improve mainly the description of the case and do not solve the main problem of novelty.

Therefore, I still cannot recommend publication of this manuscript.