Revision for Solid‐Body Breakage of the 3D‐Printed Implant Following Joint‐Sparing Surgery: A Technical Note

Abstract

Background

The advent of three‐dimensional (3D)‐printed custom‐made implants has revolutionized orthopaedic surgery, particularly in limb‐ and joint‐sparing surgeries. However, clinical experience in the revision for 3D‐printed implant breakage is lacking, and the revision surgery remains challenging. This study reported the revision of proximal tibial prosthetic reconstruction necessitated by solid‐body breakage of a 3D‐printed implant, aiming to detail the surgical techniques and evaluate postoperative outcomes.

Case Presentation

A patient diagnosed with osteosarcoma underwent joint‐sparing surgery with a 3D‐printed implant, but implant breakage occurred during subsequent follow‐up. The initial implant was broken into two parts: the proximal implant breakage part (IBP) integrated with the host bone and the distal IBP left in the prosthetic component. Four revision protocols were devised, each based on one of the four hypothesis results of taking out the initial implant. A new custom‐made implant and a series of assistance devices (“positioning devices,” “drill devices,” “tap devices,” and “separator devices”) were specifically prepared for revision surgery. The proximal IBP was taken out from the host bone, but the distal IBP was not taken out from the initial prosthetic component. The patient received the new custom‐made implant for reconstruction, with the knee joint preserved. The patient recovered uneventfully after revision surgery and achieved satisfactory function. The Musculoskeletal Tumor Society was 28 at the last follow‐up. No complications were detected during the follow‐up period.

Conclusion

Comprehensive preoperative planning and preparation, enabling the surgeon to effectively address intraoperative challenges, are crucial for the successful revision of 3D‐printed implant breakage. It is feasible to re‐implant a 3D‐printed custom‐made implant, demonstrating satisfactory clinical and functional results.

Revision for solid‐body breakage of the 3D‐printed implant. The initial implant was broken into two parts, with the proximal implant breakage part (IBP) integrated with the host bone and the distal IBP left in the prosthetic component. Four revision protocols were planned based on the four hypothesis results from taking out the initial implant. A new custom‐made implant and a series of assistance devices (“positioning devices,” “drill devices,” “tap devices,” and “separator devices”) were prepared for revision.

Background

Modular prosthetic replacement is a widely recognized technique in long bone defect reconstruction. It offers convenience, immediate stability, early weight‐bearing, and rapid rehabilitation. ¹ , ² , ³ Despite these advantages, traditional standard modular prostheses are not suitable for limb‐sparing surgery when there is limited bone stock remaining. Moreover, their application often requires the sacrifice of the adjacent joint. In contrast, recent advances in three‐dimensional (3D)‐printing allow for the fabrication of custom‐made implants. ⁴ The advent of 3D‐printed custom‐made implants with patient‐individualized stems and/or porous interfaces, enables surgeons to perform challenging limb‐ and joint‐sparing surgeries. ⁵ , ⁶ , ⁷ In our previous work, we demonstrated the successful application of a 3D‐printed implant in proximal tibial reconstruction, which creates excellent functional results due to the preservation of the knee joint. ⁸

Revision surgery for stand modular prosthesis due to mechanical failure is not uncommon in orthopaedic oncology, and several studies have documented such revisions. ⁹ , ¹⁰ , ¹¹ , ¹² Feasible revision methods for corresponding broken sites, such as corticotomy ⁹ the hollow trephine technique ¹¹ , ¹² for extracting the broken stem, and use of a retrograde inserted instrument for punching the modular prosthetic component, ¹⁰ are well documented. However, the literature on revision for 3D‐printed implant is scarce, and clinical experience is limited. This lack of data is concerning, especially because these implants are often used in limb‐ or joint‐sparing reconstruction. The revision, therefore, not only involves the implant itself but also aims to preserve the limb or joint, adding complexity to the procedure.

This study reported the revision of proximal tibial prosthetic reconstruction necessitated by the solid‐body breakage of a 3D‐printed implant, aiming to detail the surgical techniques and evaluate the postoperative outcomes.

Case Presentation

A man diagnosed with osteosarcoma in the right tibia had a challenging medical journey. Initially, the patient underwent intercalary tumor resection followed by allograft bone transplantation and internal fixation. Regrettably, allograft rejection and/or infection were observed 21 months later. This led to the removal of the allograft and internal fixation, replaced with an antibiotic‐loaded cement spacer. However, within a year, the spacer was causing intolerable pain and a limping gait due to friction between the spacer and the bone. In 2015, the spacer was removed, and the patient received a 3D‐printed custom‐made implant for the preservation of the knee joint. Unfortunately, in 2022, the patient came to our center complaining of limb pain and movement disorders of the right lower limb. X‐ray and Tomosynthesis–Shimadzu metal artifact reduction technology (T‐SMART) scans revealed the breakage of the solid‐body insertion part of the 3D‐printed implant (Figure 1). CT of the lower limbs was also conducted.

FIGURE 1.

(A) X‐ray scan at the time of implantation of the initial three‐dimensional (3D)‐printed custom‐made implant. (B, C) X‐ray scans show the breakage of the insertion part of the 3D‐printed implant (red circle). (D, E) Tomosynthesis–Shimadzu metal artifact reduction technology (T‐SMART) images indicate good osteointegration at the bone‐to‐implant interface, along with favorable bone density around the implants.

Revision Planning

The CT data of lower limbs were collected in DICOM form and imported into Mimics software (Materialize, Leuven, Belgium). According to the corresponding gray scale value, 3D models of the host bone and the initial implant were constructed (Figure 2A). The initial implant was broken into two parts: the proximal implant breakage part (IBP) integrated with the host bone and the distal IBP still within the prosthetic component. We contemplated several revision strategies based on the feasibility of removing the IBPs. Four following protocols were considered (Figure 2B).

FIGURE 2.

(A) Three‐dimensional (3D) models of the host bone and the initial 3D‐printed implant. (B) Four protocols were considered. (C) Design of the new implant, screw holes, and a side plate. The new implant was designed larger than the initial implant 1 mm in size. The screws were adjusted to avoid the initial screw positions. A custom‐made side plate, matching the revision implant and proximal tibia, was incorporated into the implant for supplementary stability. (D) Photographs of the new 3D‐printed custom‐made implant and plate. “Positioning devices” (E), “drill devices” (F), and “tap devices” (G) were prepared.

Protocol A

Both the proximal and distal IBPs could be taken out, and the new custom‐made implant was sufficient for revision surgery. This protocol was preferred because of the preservation of the knee joint and initial stem.

Protocol B

Only the proximal IBP could be taken out from the proximal tibia bone. The new custom‐made implant for the preservation of the knee joint, cutting of the cortical bone for extraction of the initial stem, and additional bone stock for revision stem fixation were also required.

Protocol C

The proximal IBP cannot be taken out from the host bone, and therefore sacrificing the knee joint would be inevitable. The distal IBP could be taken out from the prosthetic component. A tumor knee prosthesis could be assembled with the initial prosthetic component, with the initial stem preserved.

Protocol D

Both the proximal IBP and distal IBP cannot be taken out. Sacrificing the native knee joint and cutting the cortical bone are required for revision.

Revision Preparation

The new implant was designed to be 1 mm larger than the initial implant (Figure 2C). The screws were adjusted to avoid the initial screw positions. To enhance stability and reduce the risk of re‐breakage, a custom‐made side plate, compatible with the revision implant and proximal tibia, was incorporated. This plate was intended to provide additional mechanical support and evenly distributing loads and thus minimize stress on the implant. The implant and plate were manufactured using the electron beam melting technique (ARCAM Q10plus, Mölndal, Sweden) of Chunli (Tongzhou, Beijing, China). “Positioning devices,” “drill devices,” “tap devices,” and “separator devices” were specially prepared to assist with the removal of the distal IBP. Additionally, modular uncemented stem, proximal tibia prosthesis, and segment components were prepared.

Surgical Procedure

The surgery was performed by the senior surgeon (CQ T). Under general anesthesia, the original incision was selected to expose the initial implant. After removing the surrounding hyperplastic tissue, the proximal and distal IBP were identified at the site of breakage (Figure 3A). Subsequently, an attempt was made to remove the distal IBP from the initial prosthetic component. Initially, “drill devices” were used to drill holes at the core of the distal IFP with the assistance of “positioning devices”. The wear debris was cleaned away. Next, “tap devices” were used to tap an 8‐mm diameter hole for insertion of the screw of “separator devices” (Figure 3B). Following this, the “separator devices” were used in an attempt to extract the distal IFP. Unfortunately, this extraction attempt was unsuccessful despite multiple tries (Figure 3C). The procedure then progressed to cutting the cortical bone to release the affixed initial stem, culminating in the successful removal of the proximal IBP (Figure 3D). After eradicating bone around the initial implant, the proximal IBP was taken out from the host bone (Figure 3E). The revision surgery followed Protocol B (Figure 3F), wherein the new custom‐made implant and the side plate were successfully implanted. The surgical procedure lasted 4.5 h, with a blood loss of 500 mL.

FIGURE 3.

Intraoperative photographs. (A) Exposing the initial implant through the original incision. (B) Tapping with an 8‐mm diameter tap. (C) The distal implant breakage part connected tightly with the initial prosthetic component and was not taken out. (D) Removal of the proximal implant breakage part. (E) The bone defect after removing the initial implant. (F) Implantation of the new three‐dimensional‐printed custom‐made implant and plate.

Results

Post‐surgery, the operative limb was kept non‐weight‐bearing for 4 weeks. From 5 weeks after surgery, practice standing without weight and active knee motion were commenced. Subsequently, the weight gradually increased, transitioning from walking aids, double crutches, single crutches, and canes to normal walking. Follow‐up appointments were scheduled monthly for the first 3 months, then every 3 months. At each visit, the patients underwent both physical and radiographical examinations.

Over the 12‐month follow‐up period, no implant‐related complications were detected. Seven consecutive postoperative radiographic results showed that the revision implant was in place, without signs of aseptic loosening or breakage (Figure 4). The knee joint function was satisfactory, and the range of motion was 0°–125°. The limb function score was assessed according to the Musculoskeletal Tumor Society (MSTS) scoring system, which includes pain, function, emotional acceptance, use of supports, walking ability, and gait. ¹³ Each category is rated on a scale from zero to five, making 30 the highest possible total score. At the final follow‐up, the patient's MSTS score was an impressive 28, with the breakdown as follows: five for pain, four for function, five for emotional acceptance, five for use of supports, four for walking ability, and five for gait.

FIGURE 4.

Anteroposterior and lateral radiographs immediately after the revision surgery (A, B) and 12 months after the revision surgery (C, D) show that the revision implant was in place, without signs of aseptic loosening or breakage. (E) Photographs show good knee joint function.

Discussion

Three‐dimensional‐printed custom‐made implants provide an appealing reconstruction technique for limb or joint salvage surgeries. Promising functional outcomes using this technique have been reported in tibial, femoral, and humeral defect reconstruction. ³ , ⁵ , ⁶ , ⁸ , ¹⁴ , ¹⁵ Additionally, the radiographic evaluation revealed that the porous interface favored bone ingrowth for prolonged fixation. ¹⁶ However, one of the concerns associated with 3D‐printed custom‐made implants is mechanical properties. ⁴ , ¹⁷ In fact, according to a previous study, the mechanical strength of the full solid‐body implant fabricated by 3D printing is comparable to those fabricated by forging or casting. ¹⁸ However, despite the good mechanical strength of the implant produced by 3D printing technology, implant breakage can still occur. In this patient's case, several factors might have contributed to the solid‐body breakage of the implant. Initially, the 3D‐printed custom‐made implant enabled a challenging joint‐sparing procedure for this patient at the initial prosthetic reconstruction. Consequently, the patient had excellent limb function with high activity levels. Therefore, the breakage might be related to fatigue fractures of metal after long‐term weight‐bearing. The patient underwent revision surgery and received a new custom‐made implant and plate for reconstruction. During the 12‐month follow‐up, satisfactory clinical and functional outcomes were observed.

The common breakage sites include the combination of the stem and prosthetic collar, the intramedullary stem, ⁹ and the femoral prosthesis condyle. ¹⁹ Previous studies typically described methods to extract the broken implant from the host bone. However, in this case, the breakage occurred in the solid‐body insertion part of the implant, presenting unique challenges. Besides the extraction of the proximal IBP from the host bone, the distal IBP also required extraction from the prosthetic component. To the best of our knowledge, such a complex revision procedure for this type of breakage has not been previously reported. The revision methods reported previously were insufficient for our case. Special devices were required for taking out the distal IBP. The “separator devices” prepared in the present study could convert the knocking force into the force to extract the distal IBP out of the prosthetic component. However, in contrast to preoperative simulation, the distal IBP was not taken out in the revision surgery. According to previous studies, the metal parts would have fusion with atoms spread to other part, which is called cold welding. ²⁰ , ²¹ The phenomenon also reported in clinical practice in which the modular hip implant cannot be separated during revision surgery is referred to as “clinical cold welding.” ²² The “clinical cold welding” might occur in our case. The force of the “separator devices” was insufficient to separate the initial implant, which needs to be further refined and optimized.

In this study, the patient received a new custom‐made implant after the proximal IBP was removed. Considering the bone loss while taking out the proximal IBP, the implant was designed to be larger than the initial implant. In addition, to prevent the implant's further breakage, a side plate was custom‐made for this case. The postoperative limb function was satisfactory, with an MSTS score of 28. While tumor knee prosthesis replacement is a relatively straightforward procedure for revising failed intercalary prosthetic reconstructions, it inevitably involves sacrificing the knee joint. In contrast, using a custom‐made implant in our case allowed for the preservation of the knee joint, theoretically leading to better postoperative proprioception and limb function. ²³

In our case, the revision with a new 3D‐printed custom‐made implant was able to provide satisfactory clinical and functional outcomes. Preoperatively, all hypothesis results relating to taking out the initial implant were considered due to the lack of clinical experience in the revision of solid‐body implant breakage like our case. Intraoperatively, the surgeon could handle encountered problems, such as using the alternative Protocol B as the distal IBP cannot be taken out. Comprehensive preoperative planning and preparation were key to the success of this complex revision.

The study's limitations include its focus on a single case and the relatively short follow‐up period. A longer‐term follow‐up is necessary to further assess the clinical and functional outcomes of this revision. An additional limitation is the reliance on manual precision for inserting screws, which could be prone to human error. To enhance the accuracy and safety of such surgeries, especially in complex cases involving 3D‐printed implants, integrating advanced technology like robotic assistance or computer‐guided systems could be beneficial. Despite these limitations, the study's strengths are significant, particularly in addressing the under‐researched area of 3D‐printed implant breakage. Our detailed case study underscores the importance of meticulous preoperative planning, offering insights and potential strategies for surgeons facing similar challenges.

Conclusion

Comprehensive preoperative planning and preparation, enabling the surgeon to effectively address intraoperative challenges, are crucial for the successful revision of 3D‐printed implant breakage. It is feasible to re‐implant a 3D‐printed custom‐made implant, demonstrating satisfactory clinical and functional results.

Conflict of Interest Statement

The authors declare that they have no conflicts of interest.

Ethics Statement

This study was performed in accordance with the Declaration of Helsinki as revised in 2008 and was approved by the Ethics Committee of West China Hospital. The patient signed the informed consent form before surgery.

Author Contributions

Zhuangzhuang Li, Minxun Lu, Yi Luo, and Chongqi Tu were involved with the concept and design of this manuscript. Zhuangzhuang Li and Taojun Gong were involved with the acquisition of the subject and data. Zhuangzhuang Li and Chongqi Tu were involved in the design of the prosthesis. Yi Luo, Yong Zhou, Li Min, and Chongqi Tu were involved in the postsurgical evaluation of the patient. All authors contributed to the article and approved the submitted version.

Funding Information

This work was supported by the 1·3·5 Project for Disciplines of Excellence, West China Hospital, Sichuan University (ZYJC18036).