An Alumina Ceramic Total Talar Prosthesis for Avascular Necrosis of the Talus

Influence of Talar and Calcaneal Morphology on Subtalar Kinematics During Walking

BACKGROUND

Cadaver biomechanical testing suggests that the morphology of articulating bones contributes to the stability of the joints and determines their kinematics; however, there are no studies examining the correlation between bone morphology and kinematics of the subtalar joint. The purpose of this study was to investigate the influence of talar and calcaneal morphology on subtalar kinematics during walking in healthy individuals.

METHODS

Forty ankles (20 healthy subjects, 10 women/10 men) were included. Participants walked at a self-selected pace while synchronized biplane radiographs of the hindfoot were acquired at 100 images per second during stance. Motion of the talus and calcaneus was tracked using a validated volumetric model-based tracking process, and subtalar kinematics were calculated. Talar and calcaneal morphology were evaluated using statistical shape modeling. Pearson correlation coefficients were used to assess the relationship between subtalar kinematics and the morphology features of the talus and calcaneus.

RESULTS

This study found that a shallower posterior facet of the talus was correlated with the subtalar joint being in more dorsiflexion, more inversion, and more internal rotation, and higher curvature in the posterior facet was correlated with more inversion and eversion range of motion during stance. In the calcaneus, a gentler slope of the middle facet was correlated with greater subtalar inversion.

CONCLUSION

The morphology of the posterior facet of the talus was found to a primary factor driving multiplanar subtalar joint kinematics during the stance phase of gait.

CLINICAL RELEVANCE

This new knowledge relating form and function in the hindfoot may assist in identifying individuals susceptible to subtalar instability and in improving implant design to achieve desired kinematics after surgery.

Total talar replacement for metastatic pulmonary adenocarcinoma of the talus: A case report

Talar metastases from malignant tumors are rare and poorly documented. Treatment requires gradual relief of pain and preservation of function, with a choice between palliative measures and surgery. This case indicates that total talar replacement is an effective intervention for localized talar metastases and highlights the importance of early intervention. A 48-year-old man was diagnosed with a pathologic talar fracture due to talar metastases was observed after 8 years of chemotherapy following a diagnosis of lung adenocarcinoma. Despite radiotherapy, the patient's activities of daily living (ADLs) deteriorated due to pain on walking, prompting a request for surgical intervention. Total talar replacement was performed, allowing the patient to begin full weight-bearing ambulation 2 weeks post-operatively. Total talar replacement appears to be an effective treatment for localized talar metastases and should be performed as early as possible.

[Research progress in surgical treatment of avascular necrosis of talus]

Objective

To summarize the surgical treatment methods for avascular necrosis of the talus.

Methods

The recent domestic and international literature related to avascular necrosis of the talus was extensively conducted. The pathogenesis, surgical treatment methods, and prognosis were summarized.

Results

The clinical symptoms of avascular necrosis of the talus at early stage are not obvious, and most patients have progressed to Ficat-Arlet stages Ⅲ-Ⅳ and require surgical treatment. Currently, surgical treatments for this disease include core decompression, vascularized bone flap transplantation, arthroplasty, and arthrodesis, etc. Early avascular necrosis of the talus can be treated conservatively, and if treatment fails, core decompression can be considered. Arthrodesis is a remedial surgery for patients with end-stage arthritis and collapse, and in cases of severe bone loss, tibiotalocalcaneal arthrodesis and bone grafting are required. Vascularized bone flap transplantation is effective and plays a role in all stages of avascular necrosis of the talus, but the appropriate donor area for the flap still needs further to be studied.

Conclusion

The surgical treatment and the system of treatment for different stages of avascular necrosis of the talus still need to be refined.

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.

Total Talar Prosthesis, Learning from Experience, Two Reports of Total Talar Prosthesis after Talar Extrusion and Literature Review

Recently, total talar prosthesis has been proposed to substitute the talus during the management of complex talar lesions such as talar extrusion, comminuted talar fractures, or avascular necrosis. Herein, we report two cases of talar extrusion treated with total talar replacement after a high-intensity trauma. Both cases subsequently required revision surgery due to degenerative changes of the tibial plafond (arthrodesis in the first case, conversion to a total ankle prosthesis in the latter). We report and analyze the literature concerning total talar replacement to discuss strategies that could help improve prosthesis survival and reduce the incidence of osteoarthritis.

Total Talar Replacement: Surgical Technique

Background

Total talar replacement is a salvage procedure for end-stage osteonecrosis of the talus. A customized total talar implant is designed with use of computed tomography scans of the healthy opposite side and made of alumina ceramic. The use of such an implant is potentially recommended, with a guarded prognosis, for the treatment of traumatic, steroidal, alcoholic, systemic lupus erythematous, hemophilic, and idiopathic pathologies. The talus is surrounded by the tibia, fibula, calcaneus, and navicular bones, which account for a large portion of the articular surface area. Yoshinaga9 reported that alumina ceramic prostheses were superior in terms of congruency and durability of articular cartilage compared with 316L stainless steel in an in vivo test in dogs. Therefore, alumina ceramic is an ideal material for replacement of the talus to preserve postoperative hindfoot mobility.

Description

Total talar replacement is performed with the patient in a supine position. The anterior ankle approach is utilized to exteriorize the talus, facilitating dissection of the ligaments and joint capsule attached to talus. The first osteotomy is performed around the talar neck, perpendicular to the plantar surface of the foot. The talar head fragment is then removed. Subsequent talar osteotomies are performed parallel to the first cutting line, at approximately 2-cm intervals. The attaching articular capsule and ligaments are dissected in each step. The removal of the posterior talar bone fragments is succeeded by careful dissection of the ligament and joint capsule under the periosteum. After dissecting the remaining interosseous talocalcaneal ligament, the foot is distally retracted and a customized talar implant is inserted. After testing and confirming the stability and mobility of the implant, the wound is irrigated with use of normal saline solution. A suction drain is placed anterior to the implant, and the skin is closed after repairing the extensor retinaculum.

Alternatives

In cases with a limited area of necrosis, symptoms may improve with a patellar tendon-bearing brace. However, in many cases of symptomatic osteonecrosis of the talus, nonoperative treatment is not expected to improve symptoms. Alternative surgical procedures include ankle arthrodesis and hindfoot arthrodesis, but there are risks of nonunion, leg-length discrepancy as a result of extensive bone loss, and functional decline because of loss of hindfoot motion.

Rationale

Total talar replacement is a fundamentally unique treatment concept in which the entire talus is replaced with an artificial implant. Compared with ankle or hindfoot arthrodesis, this procedure preserves the range of motion of the foot and allows for earlier functional recovery. Postoperative results were satisfactory in the subjective evaluation, with no failure requiring revision. This procedure reduces the risk of postoperative failure in patients who are elderly and/or have underlying diseases, who often require a long recovery time. As the talus is a small bone with uniquely vulnerable vascularity, treatment of talar pathology is usually difficult; however, total talar replacement is a potential treatment option for patients with end-stage osteonecrosis of the talus without obesity.

Expected Outcomes

The greatest advantage of total talar replacement is the preservation of ankle and hindfoot mobility. Second, a customized talar prosthesis based on a mirrored model of the contralateral, unaffected talus will allow the smooth transfer of body weight from the lower leg to the heel and forefoot-a requirement for a stable gait. Third, the artificial talar prosthesis has a potential advantage in that it minimizes leg-length discrepancy, preventing daily inconvenience for the patient. Twenty years after the development of the implant, replacement with a total talar prosthesis resulted in a median score of 97 out of 100 on the Japanese Society for Surgery of the Foot (JSSF) Ankle-Hindfoot Scale as an objective evaluation and yielded a significant improvement in the subjective evaluation of the Ankle Osteoarthritis Scale (AOS) in a follow-up study over 10 years. The median ankle joint range of motion was 45°, and complications requiring implant replacement never occurred.

Important Tips

The skin incision should be placed at the center of the inferior tibial articular surface and curved medially to avoid the medial branch of the superficial peroneal nerve.During the resection of the talus, the attaching ligament and joint capsule are recommended to be debrided prior to osteotomy.Bone fragments should be removed as an entire block in order to avoid leaving small fragments.When inserting the artificial talus, pull the entire foot distally by grasping the heel in order to avoid excessive plantar flexion.During wound closure, the extensor retinaculum should be repaired to avoid skin bowstringing.Although favorable long-term results have been reported, postoperative outcomes in patients with high body mass index have not been adequately investigated. This procedure should be carefully selected on the basis of the physical characteristics of the patient.

Acronyms and Abbreviations

AVN = avascular necrosis (osteonecrosis)SLE = systemic lupus erythematousCAD = computer-aided designCT = computed tomographyJSSF = Japanese Society for Surgery of the FootIQR = interquartile rangeAOS = Ankle Osteoarthritis ScalePWB = partial weight-bearingW = weeks.

Total Talar Replacement for Idiopathic Osteonecrosis of the Talus: Investigation of Clinical Outcomes, Pain, ADL, QOL

Background

Treatment of osteonecrosis of the talus is challenging. Nonoperative management includes nonweightbearing treatment. Various types of hindfoot fusion procedures have been performed, but delayed union and shortening of the operated leg have reportedly occurred. In contrast, talar body prosthesis is a surgical procedure with potential that relieves pain, restores ankle joint function, and is not associated with leg-length discrepancy. The aim of this study was to investigate postoperative pain, clinical outcomes, activities of daily living (ADL), and quality of life (QOL) after total talar replacement in patients with osteonecrosis of the talus.

Methods

Ten ankles in 10 patients with idiopathic osteonecrosis of the talus who were treated with a total talar replacement between 2007 and 2015 were included in the investigation. Scores according to the visual analog scale (VAS), Japanese Society for Surgery of the Foot (JSSF) ankle-hindfoot scale, Functional Independence Measure (FIM), and the Self-Administered Foot Evaluation Questionnaire (SAFE-Q) were assessed.

Results

The VAS score significantly improved from a mean of 80 ± 8 points before surgery to 18 ± 22 points after surgery (P < .01). The JSSF ankle-hindfoot scale score significantly improved from a mean of 53 ± 12 points before surgery to 89 ± 7 points after surgery (P < .01). The FIM score significantly improved from a mean of 122 ± 1 points before surgery to 125 ± 1 points after surgery (P < .01). The mean postoperative SAFE-Q scores were as follows: 81 ± 10.3 points for pain, 78 ± 14.7 points for physical function, 90 ± 12.4 points for social function, and 83 ± 15.4 points for shoe-related.

Conclusion

Total talar replacement is a useful treatment for patients with osteonecrosis of the talus. This replacement surgery preserves the function of the ankle and subtalar joints, and improves pain, ADL, and QOL.

Level of Evidence

Level IV, case series.

Silica coated high performance oxide ceramics promote greater ossification than titanium implants: an in vivo study

BACKGROUND

This in vitro study investigated the osseointegration and implant integration of high performance oxide ceramics (HPOC) compared to titanium implants in rabbits.

METHODS

Histomorphometry was conducted around the distal, proximal, medial, and lateral aspects of the HPOC to quantify the amount of mature and immature ossification within the bone interface. Histomorphometry was conducted by a trained musculoskeletal pathologist. The region of interest (ROI) represented the percentage of surrounding area of the implant. The percentage of ROI covered by osteoid implant contact (OIC) and mature bone implant contact (BIC) were assessed. The surrounding presence of bone resorption, necrosis, and/or inflammation were quantitatively investigated.

RESULTS

All 34 rabbits survived the 6- and 12-week experimental period. All HPOC implants remained in situ. The mean weight difference from baseline was + 647.7 mg (P < 0.0001). The overall OIC of the ceramic group was greater at 6 weeks compared to the titanium implants (P = 0.003). The other endpoints of interest were similar between the two implants at all follow-up points. No difference was found in BIC at 6- and 12-weeks follow-up. No bone necrosis, resorption, or inflammation were observed.

CONCLUSION

HPOC implants demonstrated a greater osteoid implant contact at 6 weeks compared to the titanium implants, with no difference found at 12 weeks. The percentage of bone implant contact of HPOC implants was similar to that promoted by titanium implants.

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.

Avascular Osteonecrosis of the Talus: Current Treatment Strategies

Avascular osteonecrosis (AVN) of the talus (AVNT) is a painful and challenging clinical diagnosis. AVNT has multiple known risk factors and etiologies and presents at different stages in severity. Given these unique factors, the optimal treatment solution has yet to be determined. Both joint-preserving and joint-sacrificing procedures are available, including core decompression and arthrodeses. Recently, new salvage and replacement techniques have been described including vascularized pedicle bone grafts and total talus replacement using patient-specific prosthesis; however, evidence remains limited. This review examines the current trends AVNT treatment and the emerging data behind these novel techniques.

Polycarbonate-urethane coating can significantly improve talus implant contact characteristics

Talus implants can be utilized in cases of talus avascular necrosis and has been regarded as a promising treatment method. However, existing implants are made of stiff materials that directly oppose natural cartilage. The risk of long-term cartilage wear and bone fracture from the interaction between the cartilage and stiff implant surfaces has been documented in post-hemiarthroplasty of the hip, knee and ankle joints. The aim is to explore the effects of adding a layer of compliant material (polycarbonate-urethane; PCU) over a stiff material (cobalt chromium) in talus implants. To do so, we obtained initial ankle geometry from four cadaveric subjects in neutral standing to create the finite element models. We simulated seven models for each subject: three different types of talus implants, each coated with and without PCU, and a biological model. In total, we constructed 28 finite element models. By comparing the contact characteristics of the implant models with their respective biological model counterparts, our results showed that PCU coated implants have comparable contact area and contact pressure to the biological models, whereas stiff material implants without the PCU coating all have relatively higher contact pressure and smaller contact areas. These results confirmed that adding a layer of compliant material coating reduces the contact pressure and increases the contact area which in turn reduces the risk of cartilage wear and bone fracture. The results also suggest that there can be clinical benefits of adding a layer of compliant material coating on existing stiff material implants, and can provide valuable information towards the design of more biofidelic implants in the future.

Total Talar Replacements Short-Medium Term Case Series, South Africa 2019

There are few surgical options available to manage complex talar pathology that result in predictably acceptable functional and patient satisfaction scores. Recently, total talar replacement has gained popularity as a viable option. This study presents the clinical outcomes of a case series of total talar replacements in South Africa. A review of data for 8 (N = 8) consecutive patients who underwent total talus replacement between July 2014 and August 2018 was performed. The American Orthopedic Foot and Ankle Society hindfoot score was used to assess clinical function and the Short Form-36 was used to assess patient satisfaction. Patient demographics as well as data on pathology, range of motion, gait analysis, and radiological outcomes were included. The mean age was 46 (range, 23-71) years. Pathologies included trauma, avascular necrosis, and tumors. The mean duration of follow-up was 23 (range, 12-49) months. The mean American Orthopedic Foot and Ankle Society score was 79.25 (range, 69-88) and the mean Short Form-36 satisfaction score was 83.25 (range, 60-93). No revision surgeries have been performed to date. Seven patients demonstrated a mildly abnormal gait and 1 revealed a moderately abnormal gait. The patient with the longest duration of follow-up showed radiological changes of tibial wear, although he remained symptom free. Our experience with the patients described in this report leads us to believe that total talar replacement is a viable surgical option in appropriately selected patients with end-stage talar pathology in the short to medium term, without compromising future salvage options.

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

The 3D custom total talus replacement is a novel treatment for avascular necrosis of the talus. However, patients who require a total talus replacement often have concomitant degenerative changes to the tibiotalar, subtalar, or talonavicular joints. The combined 3D custom total ankle-total talus replacement (TATTR) is used for patients with an unreconstructable talus and adjacent tibial plafond involvement. The goal of performing a TATTR is to provide pain relief, retain motion at the tibiotalar joint, maintain or improve the patient's functional status, and minimize limb shortening. TATTR is made possible by 3D printing. The advent of 3D printing has allowed for the accurate recreation of the native talar anatomy with a talar dome that can be matched to a total ankle replacement polyethylene bearing. In this article, we will discuss a case of talar avascular necrosis treated with a combined TATTR and review the current literature for TATTR.

Three-dimensional printed talar prosthesis with biological function for giant cell tumor of the talus: A case report and review of the literature

BACKGROUND

Giant cell tumors (GCT) are most commonly seen in the distal femur. These tumors are uncommon in the small bones of the hand and feet, and a very few cases have been reported. A giant cell tumor of the talus is rarely seen clinically and could be a challenge to physicians.

CASE SUMMARY

We report a rare case of GCT of the talus in one patient who underwent a new reconstructive surgery technique using a three-dimensional (3D) printing talar prosthesis. The prosthesis shape was designed by tomographic image processing and segmentation using technology to match the intact side by mirror symmetry with 3D post-processing technologies. The patient recovered nearly full range of motion of the ankle after 6 mo. The visual analogue scale and American Orthopaedic Foot and Ankle Society scores were 1 and 89 points, respectively.

CONCLUSION

We demonstrated that 3D printing of a talar prosthesis is a beneficial option for GCT of the talus.

Three dimension printing talar prostheses for total replacement in talar necrosis and collapse

Background

Reconstructing bone structures and stabilizing adjacent joints are clinical challenges in treating talar necrosis and collapse (TNC). 3D printing technology has been demonstrated to improve the accuracy of talar replacement. This study aimed to evaluate anatomical talar replacement and the clinical results.

Methods

Nine patients with TNC were enrolled between 2016 and 2020. The prosthetic shape and size were designed by CT post-processing and mirror symmetry technology. The clinical outcomes included radiographic parameters of the forefoot, hindfoot, and ankle alignment, ankle activity, recurrent pain, and peri-operative complications.

Results

After a mean follow-up of 23.17 ± 6.65 months, degenerative arthritis and prosthetic dislocation and other complications were not observed on plain radiographs. Each 3D-printed talar prosthesis was placed in the original anatomical position. The parameters which have significant changes pre-operative and post-operative are as follows: talar height, 27.59 ± 5.99 mm and 34.56 ± 3.54 mm (95% CI − 13.05 to − 0.87, t = 2.94, P = 0.032) and Meary’s angle, 11.73 ± 4.79° and 4.45 ± 1.82° (95% CI 1.29~22.44, t = 2.89, P = 0.034). The AOFAS hindfoot score improved from 26.33 ± 6.62 to 79.67 ± 3.14 at the final follow-up (95% CI 43.36~63.30, t = 13.75, P = 0.000). The VAS score decreased from 6.33 ± 1.03 to 0.83 ± 0.75 (95% CI 4.40~6.60, t = 12.84, P = 0.000). The post-operative satisfaction scores regarding pain relief, activities of daily living, and return to recreational activities were good to excellent, and the change of activity range was statistically significant.

Conclusions

The 3D printing patient-specific total talar prostheses allowed anatomical reconstruction in TNC. This novel treatment with 3D-printed prostheses could serve as a reliable patient-specific alternative in TNC.