Total Ankle Total Talus Replacement Using a 3D Printed Talus Component: A Case Report

Clinical validation of enhanced CT imaging for distal radius fractures through conditional Generative Adversarial Networks (cGAN)

BACKGROUND/PURPOSE

Distal radius fractures (DRFs) account for approximately 18% of fractures in patients 65 years and older. While plain radiographs are standard, the value of high-resolution computed tomography (CT) for detailed imaging crucial for diagnosis, prognosis, and intervention planning, and increasingly recognized. High-definition 3D reconstructions from CT scans are vital for applications like 3D printing in orthopedics and for the utility of mobile C-arm CT in orthopedic diagnostics. However, concerns over radiation exposure and suboptimal image resolution from some devices necessitate the exploration of advanced computational techniques for refining CT imaging without compromising safety. Therefore, this study aims to utilize conditional Generative Adversarial Networks (cGAN) to improve the resolution of 3 mm CT images (CT enhancement).

METHODS

Following institutional review board approval, 3 mm-1 mm paired CT data from 11 patients with DRFs were collected. cGAN was used to improve the resolution of 3 mm CT images to match that of 1 mm images (CT enhancement). Two distinct methods were employed for training and generating CT images. In Method 1, a 3 mm CT raw image was used as input with the aim of generating a 1 mm CT raw image. Method 2 was designed to emphasize the difference value between the 3 mm and 1 mm images; using a 3 mm CT raw image as input, it produced the difference in image values between the 3 mm and 1 mm CT scans. Both quantitative metrics, such as peak signal-to-noise ratio (PSNR), mean squared error (MSE), and structural similarity index (SSIM), and qualitative assessments by two orthopedic surgeons were used to evaluate image quality by assessing the grade (1~4, which low number means high quality of resolution).

RESULTS

Quantitative evaluations showed that our proposed techniques, particularly emphasizing the difference value in Method 2, consistently outperformed traditional approaches in achieving higher image resolution. In qualitative evaluation by two clinicians, images from method 2 showed better quality of images (grade: method 1, 2.7; method 2, 2.2). And more choice was found in method 2 for similar image with 1 mm slice image (15 vs 7, p = 201).

CONCLUSION

In our study utilizing cGAN for enhancing CT imaging resolution, the authors found that the method, which focuses on the difference value between 3 mm and 1 mm images (Method 2), consistently outperformed.

Outcomes of cobalt-chrome 3D-printed total talus replacement with and without combined total ankle replacement

BACKGROUND

Collapse of the talus and peri-talar arthritis pose treatment challenges due to the anatomy and location of the talus as a keystone of the foot and ankle. Custom 3D-printed total talus replacement (TTR) and combined total ankle total talus replacement (TATTR) have emerged as treatment options for these pathologies. However, the safety and efficacy of these implants is unknown due to the limited number of cases and short follow-up durations.

METHODS

This was a retrospective study to assess surgical outcomes of patients who underwent a TTR and TATTR with or without subtalar fusion. Patient demographics, intraoperative parameters, device related surgical and non-surgical events, imaging and clinical evaluations, and patient reported outcome (PRO) measures were compiled.

RESULTS

A total of 38 patients received a custom 3D-printed implant with mean follow-up time of 22.1 (range: 12-45) months. In this cohort, 7 (18.4 %) required secondary surgery and 3 (7.9 %) required implant removal. Multivariate logistic regression revealed that patient diagnosis of depression was a significant predictor of secondary surgery with an OR 17.50 (p = 0.037). Significant postoperative improvements were observed in the talocalcaneal height (p = 0.005) and talar declination angle (p = 0.013) for the TATTR group. VAS and PROMIS pain interference (PI) scores demonstrated an initial significant improvement in pain, but this improvement did not maintain significance at most recent follow-up. However, there was a significant increase in the PROMIS physical function (PF) scores (p = 0.037) at most recent follow-up.

CONCLUSION

These results demonstrate that TTR and TATTR provide significant improvement in post-operative radiographic foot and ankle alignment and physical function at the two-year timepoint. PRO findings suggest that patients are more active after surgery. Surgeons considering proceeding with either of these procedures should counsel patients about pain and functional outcomes as well as realistic expectations in patients with depression.

LEVEL OF EVIDENCE

Level 3.

3D Printing Materials and Technologies for Orthopaedic Applications

SUMMARY

3D printing technologies have evolved tremendously over the last decade for uses in orthopaedic surgical applications, including being used to manufacture implants for spine, upper extremity, foot and ankle, oncologic, and traumatic reconstructions. Materials used for 3D-printed orthopaedic devices include metals, degradable and nondegradable polymers, and ceramic composites. There are 2 primary advantages for use of 3D printing technologies for orthopaedics: first, the ability to create complex porous lattices that allow for osseointegration and improved implant stability and second, the enablement of complex geometric designs allowing for patient-specific devices based on preoperative imaging. Given continually evolving technology, and the relatively early stage of the materials and 3D printers themselves, the possibilities for continued innovation in orthopaedics are great.

Outcomes following total ankle total talus replacement: A systematic review

BACKGROUND

Prosthetic substitution of the talus presents a significant challenge to the foot and ankle surgeon. The shear and compressive forces on the talus and its tenuous blood supply lead to high rates of avascular necrosis and eventual talar collapse. The purpose of this systematic review is to evaluate whether total ankle total talus replacement (TATTR) leads to improved clinical and radiographic outcomes with appropriate safety metrics in patients with a history of avascular necrosis or significant trauma.

METHODS

We searched the concepts of talus, prosthesis, and arthroplasty in MEDLINE (PubMed), Embase (Elsevier), CINAHL Complete (EBSCOhost), and Scopus (Elsevier) from the database's inception through March 9, 2023. Inclusion Criteria were 1) previous trauma to the talus, 2) post-traumatic arthritis to the tibiotalar joint, 3) avascular necrosis of talus, 4) multiple failed prior interventions, 5) degenerative osteoarthritis to the tibiotalar joint, and 6) inflammatory arthropathy to tibiotalar joint. Patients less than 18 years of age and manuscripts in non-English languages were excluded.

RESULTS

Of the 7625 references, 16 studies met the inclusion criteria, yielding data from 136 patients (139 ankles). The studies varied in design, with case reports and retrospective case series being predominant. The overall weighted average modified Coleman Methodology Score (mCMS) was 70.4 out of 100, indicating moderate flaws in study design that may be subject to various forms of bias and possible confounders. Demographics showed a diverse range of etiologies, with alumina ceramic being the primary prosthesis material. Functional scores demonstrated improvements in dorsiflexion and plantarflexion, although patient-reported outcome measures (PROs) were inconsistently reported. Complications included fractures, heterotopic ossification, prolonged wound healing, and infections. Revision details were sparsely reported.

CONCLUSION

TATTR is a promising treatment modality for improving short-term functional outcomes for patients with avascular necrosis or trauma-related issues. However, this systematic review underscores the need for standardized reporting, longer-term follow-ups, and further research to establish the procedure's efficacy and safety, particularly in comparison to other treatment modalities.

LEVEL OF EVIDENCE

III, Systematic Review of Level IV Studies.

Partial talar replacement with a novel 3D printed prosthesis

BACKGROUND

The treatment of talus avascular necrosis (AVN) is challenging owing to its unique anatomical features. Despite decades of studies, till date, there is no appropriate treatment for talus AVN. Therefore, surgeons need to develop newer surgical methods. In the present study we introduce a new surgical method, 3D printed partial talus replacement (PTR), to treat partial talus necrosis and collapse (TNC).

METHODS

A male patient with talus AVN underwent PTR in our hospital. The morphology of the talus was quantified using 3D computed tomography (CT) imaging. A novel 3D printed titanium prothesis was designed and manufactured according to the findings of the CT imaging. The prosthesis was applied during talus replantation surgery to reconstruct the anatomical structure of the ankle. The follow-up period for this patient was 24 months. The visual analog scale (VAS) scores before and after surgery, American Orthopedic Foot and Ankle Score (AOFAS), ankle range of motion, and postoperative complications were recorded to evaluate the prognosis.

RESULTS

The anatomical structure of the talus was reconstructed. The patient was satisfied with the effects of treatment, recovery, and function. The VAS score decreased from 5 to 1. The AOFAS improved from 70 to 93. The range of motion remained the same as that during the pre-operation. The patient returned to a normal life.

CONCLUSION

3D printed PTR is a new surgical method for talus AVN that can provide satisfactory outcomes. In future, PTR might be an effective and preferential treatment for the treatment of partial talus AVN and collapse.

Evaluating Failure Mechanisms for Total Talus Replacement: Contemporary Review

BACKGROUND

As total talus replacement (TTR) grows in popularity as a salvage option for talar collapse, a critical evaluation of the complications associated with this procedure is indicated.

METHODS

In this review of the literature, we present a patient report and provide a review of several complications seen after TTR, including ligamentous instability, infection, and adjacent joint osteoarthritis, which we have encountered in our practice.

RESULTS

Total talus replacement has the potential to reduce pain and preserve range of motion. However, the treating surgeon must be cognizant of the variety of adverse outcomes. We have presented cases of potential devastating complications from our own clinical experience and the literature.

CONCLUSIONS

In conclusion, TTR may have utility in the properly selected patient with end-stage talar collapse, but implant composition, indications, and patient demographic variables complicate the interpretation of the literature.Levels of Evidence: Level III.

The use of 3D printing technology in limb reconstruction. Inspirations and challenges

The management of septic non-unions with associated bone necrosis is challenging, especially when the resulting bone defect after the debridement is extensile. Different techniques have been described in the literature for the treatment of these demanding cases, with the most prominent being free vascularized Fibular graft and bone transport with distraction osteogenesis principles. Recently, 3D printing technology has been increasingly utilized in many complex orthopaedic pathologies. However, the application of those advancements regarding septic non-unions with residual bone defect has not been previously studied. This study presents a novel 3D printing technique for the management of an infected critical bone deficit of the tibia. Queries, challenges and future perspectives concerning the recruiting of 3D printing technology in limb reconstruction are also being discussed. Clinical Evidence Level: IV.

An overview of 3D printed metal implants in orthopedic applications: Present and future perspectives

With the ability to produce components with complex and precise structures, additive manufacturing or 3D printing techniques are now widely applied in both industry and consumer markets. The emergence of tissue engineering has facilitated the application of 3D printing in the field of biomedical implants. 3D printed implants with proper structural design can not only eliminate the stress shielding effect but also improve in vivo biocompatibility and functionality. By combining medical images derived from technologies such as X-ray scanning, CT, MRI, or ultrasonic scanning, 3D printing can be used to create patient-specific implants with almost the same anatomical structures as the injured tissues. Numerous clinical trials have already been conducted with customized implants. However, the limited availability of raw materials for printing and a lack of guidance from related regulations or laws may impede the development of 3D printing in medical implants. This review provides information on the current state of 3D printing techniques in orthopedic implant applications. The current challenges and future perspectives are also included.

Functional Outcomes and Complications Associated With Total Talus Arthroplasty: A Systematic Review

Total talus arthroplasty (TTA) is a motion sparing procedure which can be utilized in specific and unique cases of talar necrosis and/or collapse. Literature on TTA is limited and predominantly composed of case studies or case reports. The purpose of this publication is to compile a systematic review of functional outcomes and complications associated with TTA. A search of current literature on TTA with >1-year follow-up was performed. Studies that described talar body implants or talonavicular implants were excluded. Twenty articles met inclusion criteria, which represented 161 TTAs. The average follow-up was 37.35 months (9-60 months). The indication for a TTA was predominately avascular necrosis of the talus, comprising 75.78% (122/161) of cases. The overall complication rate was 9.32% (15/161), with wound healing complications (5/161), replacement or implantation of a tibial component (4/161), and medial malleolus fracture (3/161) being the most common. One patient required proximal amputation due to residual pain and deformity. Functionally, American Orthopedic Foot and Ankle Score increased from 27.93 preoperative to 81.99 postoperative and Japanese Society for Surgery of the Foot Score increased from 43.2 preoperative to 89.34 postoperative. Visual analog scale pain score decreased from 6.44 to 2.60. Total ankle range of motion increased from 36.60° to 46.74°. Ankle plantarflexion increased by 3.45° and ankle dorsiflexion increased by 6.69°. Overall, available literature on TTA appears to be in favor of the procedure when indicated.Levels of Evidence: 4.

A Novel Technique for Lateral Ankle Ligament Reconstruction with Total Ankle Total Talus Replacement: A Case Report

CASE

A 65-year-old man with severe left talar avascular necrosis, arthritis, and chronic lateral ankle instability underwent total ankle total talus replacement (TATTR) with lateral ligament reconstruction. Tibial component placement was performed using preoperative computed tomography navigation and patient-specific guides. A custom, total talus replacement to mate with the fixed-bearing tibial component was implanted. Last, a modified Brostrom procedure was performed to restore lateral ankle stability. The patient has performed well through 1 year with improved pain-free function.

CONCLUSION

This case report details a novel technique for performing a modified Brostrom procedure in conjunction with TATTR to restore lateral ankle stability.

Outcomes following total talus replacement: A systematic review

INTRODUCTION

The treatment of pathologic changes to the talus and surrounding joints presents a unique challenge to the foot and ankle surgeon. The purpose of this systematic review is to summarize the literature for unconstrained (no surrounding fusion or replacement) total talus replacement (TTR) and evaluate whether it leads to improved clinical and radiographic outcomes and appropriate safety metrics.

METHODS

Concepts of talus and arthroplasty were searched in MEDLINE, Embase, CINAHL Complete, and Scopus from 2005 to 2021. Inclusion Criteria were 1) previous trauma to the talus, 2) post-traumatic or degenerative arthritis to the tibiotalar joint, 3) avascular necrosis of talus, 4) multiple failed prior interventions, and 5) inflammatory arthropathy to tibiotalar joint. Manuscripts in non-English languages or those with concomitant total ankle arthroplasty or revision arthroplasty were excluded.

RESULTS

Twenty-two studies of 191 patients (196 ankles) were included. Nineteen studies utilized third generation implants, two studies used first generation (n = 9) and one study used second generation implants (n = 14) made largely of ceramic (n = 84), cobalt chrome (n = 49), or titanium (n = 24). Patient-reported outcome measures were favorable in all described categories (Table 4) with ten studies reporting an average postoperative change of + 2.92° of dorsiflexion and - 2.05° plantarflexion at final follow-up. The most common adverse outcome was adjacent joint arthritis with five studies reporting some degree of postoperative, degenerative changes in the surrounding joints (n = 52).

CONCLUSION

TTR is an alternative to joint sacrificing procedures to maintain range of motion through the tibiotalar joint and allow for maintenance of normal foot and ankle biomechanics. Despite promising early- and mid-term outcomes, future, prospective, randomized research should be conducted to better assess survivorship and complication rates with direct comparison of TTR to existing forms of salvage options for advanced talar pathology.

LEVEL OF EVIDENCE

III, Systematic Review of Level IV Studies.

Dynamic finite element analyses to compare the influences of customised total talar replacement and total ankle arthroplasty on foot biomechanics during gait

Objective, Total talar replacement (TTR) using a customised talus prosthesis is an emerging surgical alternative to conventional total ankle arthroplasty (TAA) for treating ankle problems. Upon satisfying clinical reports in the literature, this study explored the advantages of TTR in restoring foot biomechanics during walking compared with TAA through computational simulations.Methods, A dynamic finite element foot model was built from the MRIs of a healthy participant and modified into two implanted counterparts (TTR and TAA) by incorporating the corresponding prosthetic components into the ankle joint. Twenty bony parts, thirty-nine ligament/tendon units, nine muscle contractors, and bulk soft tissue were included in the intact foot model. The TTR prosthesis was reconstructed from the mirror image data of the participant's contralateral talus and the TAA prosthesis was modelled by reproducing the Scandinavian ankle replacement procedure in the model assembly. The model was meshed with explicit deformable elements and validated against existing experimental studies that have assessed specific walking scenarios. Simulations were performed using the boundary conditions (time-variant matrix of muscle forces, segment orientation, and ground reaction forces) derived from motion capture analyses and musculoskeletal modelling of the participant's walking gait. Outcome variables, including foot kinematics, joint loading, and plantar pressure were reported and compared among the three model conditions.

RESULTS

Linear regression indicated a better agreement between the TTR model and intact foot model in plots of joint motions and foot segment movements during walking (R² ​= ​0.721-0.993) than between the TAA and intact foot (R² ​= ​0.623-0.990). TAA reduced talocrural excursion by 21.36%-31.92% and increased (MTP) dorsiflexion by 3.03%. Compared with the intact foot, TTR and TAA increased the midtarsal joint contact force by 17.92% and 10.73% respectively. The proximal-to-distal force transmission within the midfoot was shifted to the lateral column in TTR (94.52% or 210.54 ​N higher) while concentrated on the medial column in TAA (41.58% or 27.55 ​N higher). The TTR produced a plantar pressure map similar to that of the intact foot. TAA caused the plantar pressure centre to drift medially and increased the peak forefoot pressure by 7.36% in the late stance.

CONCLUSION

The TTR better reproduced the foot joint motions, segment movements, and plantar pressure map of an intact foot during walking. TAA reduced ankle mobility while increasing movement of the adjacent joints and forefoot plantar pressure. Both implant methods changed force transmission within the midfoot during gait progression.The translational potential of this article Our work is one of the few to report foot segment movements and the internal loading status of implanted ankles during a dynamic locomotion task. These outcomes partially support the conjecture that TTR is a prospective surgical alternative for pathological ankles from a biomechanical perspective. This study paves the way for further clinical investigations and systematic statistics to confirm the effects of TTR on functional joint recovery.

Total Talar Replacement With Custom-Made Vitallium Prosthesis for Talar Avascular Necrosis

Background: The current study investigated the application of three-dimensional (3D) printing technology in the treatment of talar avascular necrosis (TAN). Custom-made Vitallium talar prostheses were designed and generated via 3D printing. We hypothesized that these talar prostheses would facilitate more stable positioning, better ergonomically fit the ankle joint surfaces, and promote favorable long-term prognoses. Material and Methods: Computed tomography scans of both ankle joints were acquired from three patients diagnosed with TAN. The talar on the unaffected side was used as the design blueprint. Hence, with the aid of 3D printing technology a customized talar prosthesis made from a novel Vitallium alloy could be manufactured for each individual patient. Results: In all three cases there were no signs of prosthesis loosening or substantial degenerative change in the surrounding area of the joint, but small osteophytes were observed on the tibial side and navicular side. No chronic infection or other prosthesis-related complications were observed in any of the patients. All three were able to walk without pain at the most recent follow-up. Conclusion: With the aid of 3D printing and a novel Vitallium alloy, total talar replacement achieved encouraging results in 3/3 patients. All patients were satisfied with their joint function, and were able to return to their daily activities without limitations. Although more cases and longer-term follow-up periods are required, the success rate reported herein is encouraging.

Talonavicular Joint-Sparing 3D Printed Navicular Replacement for Osteonecrosis of the Navicular

Pathology of the navicular can be a difficult entity to treat, particularly when the injury has progressed to osteonecrosis. While various nonoperative and operative modalities have been described, the emerging field of additive manufacturing has become a potential solution to this difficult problem in certain scenarios. While these implants have largely been used for fusion in the past, the concept of joint sparing with 3D printed implants is also emerging, and this case highlights a patient treated with a talonavicular joint-sparing, patient-specific 3D printed total navicular replacement.

Clinical Use of Talar Prostheses

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The blood supply to the talus is vulnerable to damage, making the talus susceptible to osteonecrosis, with limited treatment options.

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Talar bone replacement has been investigated as a treatment option to preserve ankle function and maintain limb length.

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Successful talar bone replacements have been performed for the past >35 years, with variations in design, methods of fixation, materials, and manufacturing techniques.

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The designs of talar prostheses range from custom-made partial (talar body) or total prostheses to prefabricated universal (non-custom-made) prostheses.

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Total talar prostheses have been demonstrated to function better than partial talar prostheses; however, there is a need for long-term studies regarding custom-made total talar prostheses and prefabricated universal talar prostheses in order to determine their long-term effectiveness.

Three-dimensional Printing in Orthopaedic Surgery: Current Applications and Future Developments

Three-dimensional (3D) printing is an exciting form of manufacturing technology that has transformed the way we can treat various medical pathologies. Also known as additive manufacturing, 3D printing fuses materials together in a layer-by-layer fashion to construct a final 3D product. This technology allows flexibility in the design process and enables efficient production of both off-the-shelf and personalized medical products that accommodate patient needs better than traditional manufacturing processes. In the field of orthopaedic surgery, 3D printing implants and instrumentation can be used to address a variety of pathologies that would otherwise be challenging to manage with products made from traditional subtractive manufacturing. Furthermore, 3D bioprinting has significantly impacted bone and cartilage restoration procedures and has the potential to completely transform how we treat patients with debilitating musculoskeletal injuries. Although costs can be high, as technology advances, the economics of 3D printing will improve, especially as the benefits of this technology have clearly been demonstrated in both orthopaedic surgery and medicine as a whole. This review outlines the basics of 3D printing technology and its current applications in orthopaedic surgery and ends with a brief summary of 3D bioprinting and its potential future impact.