The use of a ceramic talar body prosthesis in patients with aseptic 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.

Three-dimensional printed custom-made modular talus prosthesis in patients with talus malignant tumor resection

BACKGROUND

Talar malignant tumor is extremely rare. Currently, there are several alternative management options for talus malignant tumor including below-knee amputation, tibio-calcaneal arthrodesis, and homogenous bone transplant while their shortcomings limited the clinical application. Three-dimensional (3D) printed total talus prosthesis in talus lesion was reported as a useful method to reconstruct talus, however, most researches are case reports and its clinical effect remains unclear. Therefore, the current study was to explore the application of 3D printed custom-made modular prosthesis in talus malignant tumor.

METHODS

We retrospectively analyzed the patients who received the 3D printed custom-made modular prosthesis treatment due to talus malignant tumor in our hospital from February 2016 to December 2021. The patient's clinical data such as oncology outcome, operation time, and volume of blood loss were recorded. The limb function was evaluated with the Musculoskeletal Tumor Society 93 (MSTS-93) score, The American Orthopedic Foot and Ankle Society (AOFAS) score; the ankle joint ranges of motion as well as the leg length discrepancy were evaluated. Plain radiography and Tomosynthesis-Shimadzu Metal Artefact Reduction Technology (T-SMART) were used to evaluate the position of prosthesis and the osseointegration. Postoperative complications were recorded.

RESULTS

The average patients' age and the follow-up period were respectively 31.5 ± 13.1 years; and 54.8 months (range 26-72). The medium operation time was 2.4 ± 0.5 h; the intraoperative blood loss was 131.7 ± 121.4 ml. The mean MSTS-93 and AOFAS score was 26.8 and 88.5 respectively. The average plantar flexion, dorsiflexion, varus, and valgus were 32.5, 9.2, 10.8, and 5.8 degree respectively. One patient had delayed postoperative wound healing. There was no leg length discrepancy observed in any patient and good osseointegration was observed on the interface between the bone and talus prosthesis in all subjects.

CONCLUSION

The modular structure of the prosthesis developed in this study seems to be convenient for prosthesis implantation and screws distribution. And the combination of solid and porous structure improves the initial stability and promotes bone integration. Therefore, 3D printed custom-made modular talus prosthesis could be an alternative option for talus reconstruction in talus malignant tumor patients.

Natural course of talar avascular necrosis during short-term follow-up and factors associated with Disease progression

BACKGROUND

This retrospective cohort study aimed to investigate the natural history of talar avascular necrosis (AVN) during short-term outpatient follow-up and to identify the risk factors for progression to collapse and arthritic changes.

METHODS

Thirty-four cases of talar AVN from 34 patients (15 males, 19 females) were included. The mean age of the patients was 48.9 years (SD 16.0 years) and the mean follow-up period was 39.5 months (SD 42.0 months). The patients were divided into two groups i.e., progression and non-progression groups. The progression group consisted of those who showed aggravation of the Ficat stage during the follow-up period or advanced arthritis of the ankle joint (Ficat stage 4) at presentation. Demographic data and information regarding BMI, medical comorbidities, trauma history, bilaterality, and location of the lesion (shoulder vs. non-shoulder lesions) were collected. Following the univariate analysis, a binary logistic regression analysis was performed.

RESULTS

The location of the talar AVN was the only significant factor (p = 0.047) associated with disease progression. A total of 14.3% (2 of 14) of the central (non-shoulder) talar AVN lesions showed progression, while 50% (10 of 20) of shoulder lesions aggravated during follow-up. Age, sex, bilaterality, medical comorbidities, and trauma history were not associated with progressive talar collapse or subsequent arthritic changes in talar AVN.

CONCLUSIONS

Conservative treatment should be considered for a central lesion of the talar AVN because it tends to remain stable without progression. A more comprehensive study with a larger study population is required to establish the surgical indications for talar AVN.

LEVEL OF EVIDENCE

Prognostic level III.

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.

Ankle and Foot Arthroplasty and Prosthesis: A Review on the Current and Upcoming State of Designs and Manufacturing

The foot and ankle serve vital roles in weight bearing, balance, and flexibility but are susceptible to many diverse ailments, making treatment difficult. More commonly, Total Ankle Arthroplasty (TAA) and Total Talus Replacement (TTR) are used for patients with ankle degeneration and avascular necrosis of the talus, respectively. Ankle prosthesis and orthosis are also indicated for use with lower limb extremity amputations or locomotor disability, leading to the development of powered exoskeletons. However, patient outcomes remain suboptimal, commonly due to the misfitting of implants to the patient-specific anatomy. Additive manufacturing (AM) is being used to create customized, patient-specific implants and porous implant cages that provide structural support while allowing for increased bony ingrowth and to develop customized, lightweight exoskeletons with multifunctional actuators. AM implants and devices have shown success in preserving stability and mobility of the joint and achieving fast recovery, as well as significant improvements in gait rehabilitation, gait assistance, and strength for patients. This review of the literature highlights various devices and technologies currently used for foot and ankle prosthesis and orthosis with deep insight into improvements from historical technologies, manufacturing methods, and future developments in the biomedical space.

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.

Assessment of Changes in Hindfoot Alignment of Total Ankle Arthroplasty for Ankle Osteoarthritis on Weightbearing Subtalar X-ray View

Background

Recovering normal hindfoot alignment and correcting deformity of the ankle joint following total ankle arthroplasty (TAA) in osteoarthritis (OA) is essential for improving clinical outcomes and increasing long-term survival. We aim to evaluate hindfoot alignment following standard TAA compared to TAA with a total talar prosthesis ("combined TAA") in varus-type OA patients.

Methods

This retrospective study was conducted between 2010 and 2022. We included 27 patients (30 feet) who underwent standard TAA and 19 patients (22 feet) who underwent combined TAA. Hindfoot alignment at the subtalar joint was measured by weightbearing subtalar radiographic view before and after surgery.

Results

In the standard TAA, the angle between the tibial shaft axis and the articular surface of the talar dome joint (TTS) changed from 75 to 87 degrees (P < .01), the angle between the tibial axis and the surface on the middle facet (TMC) from 89 to 94 degrees (P < .01), and the angle between the tibial axis and the surface on the posterior facet (TPC) from 80 to 84 degrees (P < .01). The angle between the articular surface of the talar dome and the posterior facet of the calcaneus (SIA) decreased from 4.7 to -2.5 degrees (P < .01). In the combined TAA, TTS angle changed from 77 to 88 degrees (P < .01), TMC angle from 93 to 101 degrees (P < .01), TPC angle from 84 to 90 degrees (P < .05), and SIA from 6.6 to 2.1 degrees (P < .01). Varus deviation to the subtalar joint (TMC, TPC) significantly improved postoperatively in both groups. However, TPC was smaller than TTS and SIA was negative in standard TAA, and TPC was larger than TTS and SIA was positive in combined TAA.

Conclusion

The amount of correction of the subtalar joint differed depending on the ligament dissection of the subtalar joint and shape of the talar component.

Level of Evidence

Level III, retrospective cohort study.

Ten-Year Follow-Up of a Customized Total Talar Prosthesis for Revision Total Ankle Arthroplasty: A Case Report

CASE

A 74-year-old woman with rheumatoid arthritis had undergone total ankle arthroplasty (TAA) for severe ankle joint destruction at our hospital 14 years earlier. Radiographs of the ankle revealed displacement of the tibial component and subsidence of the talar component. Revision TAA was performed using a customized alumina ceramic total talar prosthesis.

CONCLUSION

The 10-year outcome of revision TAA with a total talar prosthesis was satisfactory, with no postoperative complications, such as displacement of the tibial component, dislocation of alumina ceramic artificial talus, or progression of degenerative changes in the talonavicular and subtalar joints.

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.

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.

Total Talus Replacements

Background

Total talus replacements are a surgical treatment for talar avascular necrosis (AVN) replacing the entire talus. The potential for total talus replacements has increased with the advent of patient-specific implants using 3D printing based on computed tomographic scanning of the ipsilateral or contralateral talus. The primary aim of this review is to summarize the literature on total talus replacements, providing a historical survey, indications, controversies, complications, survival, and functional outcomes.

Methods

A systematic review was performed. Articles with survival of total talus replacements were included. Basic percentages and a critical review of the literature was performed.

Results

Nine articles with 115 patients were included. The mean age ranged from 27.6 to 72 years, but with 5 studies having a mean age of <50 years. Mean follow-up ranged from 12.8 to 152 months. The most common indication was avascular necrosis in 67 patients (58%). Five studies used customized implants and 4 studies used 3D printing. Four studies used ceramic prostheses, 3 cobalt chromium, 1 stainless steel, and 1 titanium with ceramic surface. Three studies involved a talus replacement in conjunction with an ankle replacement. Postoperative complications ranged from 0% to 33%. Of 24 functional outcomes scores, 66.7% demonstrated significant improvement.

Conclusion

Total talus replacements are a promising alternative to tibiotalocalcaneal fusion for patients with avascular necrosis of the talus; however, further studies are required to ensure reliable outcomes prior to widespread adoption of this technology.

Level of Evidence

Level IV, review of case series.

Reconstruction after Talar Tumor Resection: A Systematic Review

This systematic review investigated the functional outcomes and complications of reconstruction methods after talar tumor resection. A systematic search of PubMed, Embase, and the Cochrane Central Register of Controlled Trials databases identified 156 studies, of which 20 (23 patients) were ultimately included. The mean Musculoskeletal Tumor Society scores in the groups reconstructed using tibiocalcaneal fusion (n = 17), frozen autograft (n = 1), and talar prosthesis (n = 5) were 77.6 (range 66-90), 70, and 90 (range 87-93), respectively. Regarding complications, sensory deficits were observed in one patient (6%) and venous thrombosis in two patients (12%) in the tibiocalcaneal fusion group, while osteoarthritis was observed in one patient (100%) in the frozen autograft group. No complications were observed in the talar prosthesis group. Reconstruction with talar prosthesis seems preferable to conventional tibiocalcaneal fusion after talar tumor resection because it offers better function and fewer complications. However, as this systematic review included only retrospective studies with a small number of patients, its results require re-evaluation in future randomized controlled trials with larger numbers of patients.

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.

Early Outcomes of Combined Total Ankle Total Talus Replacement Using a 3D-Printed Talus Component With Hindfoot Arthrodesis

Late-stage talar avascular necrosis (AVN) results in devascularization of the talus with osteonecrosis and subchondral collapse. A combined total ankle and total talus replacement (TATTR) with hindfoot arthrodesis may be utilized for end-stage talar AVN with tibiotalar and hindfoot joint arthritis. The purpose of this study is to evaluate the short-term outcomes of combined TATTR with hindfoot arthrodesis. Patients who underwent a combined TATTR or TTR with a hindfoot arthrodesis (subtalar with or without talonavicular arthrodesis) from 2016 to 2020 were retrospectively reviewed. Patient demographics, comorbidities, and surgical data were collected. Outcomes included the Visual Analog Scale (VAS) scores, range of motion, radiographic parameters, union rates, and complications. A total of 18 patients were reviewed. Nine patients were included with an average of 19.4 months follow-up. Significant postoperative improvements were observed in VAS scores (P < .001), ankle plantarflexion (P = .04), talocalcaneal height (P = .03), and tibiotalar alignment (P = .02). All patients achieved a successful union of their subtalar and talonavicular joints arthrodesis. There was one reoperation for a persistent varus ankle deformity. This is the first study to evaluate the clinical outcomes, radiographic outcomes, and union rate in combined TATTR with hindfoot arthrodesis. The early results demonstrated significant clinical improvement with 100% hindfoot union rate and no prosthetic failure.Level of Evidence: IV.

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.

The Long-Term Clinical Results of Total Talar Replacement at 10 Years or More After Surgery

BACKGROUND

Total talar replacement has been reported to have favorable short-term and intermediate-term results for the treatment of osteonecrosis of the talus. The purpose of this study was to evaluate the long-term clinical results of total talar replacement for a minimum of 10 years after the surgical procedure.

METHODS

From October 2005 to April 2011, 19 ankles in 18 patients (1 male and 17 female) were treated using a total talar prosthesis for osteonecrosis of the talus. The median follow-up period was 152 months (interquartile range [IQR], 138, 160 months). The Ankle Osteoarthritis Scale (AOS) score, the Japanese Society for Surgery of the Foot (JSSF) Ankle-Hindfoot Scale score, and the presence of osteophytes and degenerative changes in the adjacent joints were assessed preoperatively and at the final follow-up. Subsidence of the prosthesis was also assessed at the earliest opportunity for full weight-bearing and the final follow-up. The postoperative range of motion of the ankle was assessed at the final follow-up.

RESULTS

The median scores for all subscales of the AOS significantly improved. The median JSSF Ankle-Hindfoot Scale score significantly improved from 58 (IQR, 55, 59.5) to 97 (IQR, 87, 99.5). In the subcategories of this scale, the median pain score improved from 20 (IQR, 20, 20) to 40 (IQR, 30, 40), and the median function score improved from 28 (IQR, 26, 30.5) to 47 (IQR, 47, 50). The median postoperative range of motion of the ankle was 45° (IQR, 42.5°, 55°). Subsidence of the implant was not recognized at the final follow-up (p = 0.083). Proliferation of osteophytes and degenerative changes in the adjacent joints did not affect the overall results.

CONCLUSIONS

The customized alumina ceramic total talar prosthesis produced stable clinical outcomes over 10 years, and the patients treated with total talar replacement showed favorable clinical results over this time frame.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Comparison of Clinical Outcomes Between Ceramic-Based Total Ankle Arthroplasty with Ceramic Total Talar Prosthesis and Ceramic-Based Total Ankle Arthroplasty

BACKGROUND

Total ankle arthroplasty (TAA) has become one of the standard surgical treatments for patients with end-stage ankle osteoarthritis (OA). In recent years, TAA with total talar prosthesis (combined TAA) has been used for ankle OA patients with talar osteonecrosis, with severe talar collapse, or with subtalar joint OA. The purpose of this study was to investigate the functional and clinical outcomes of combined TAA, compared with conventional TAA.

METHODS

Forty-six ankles (44 patients, 32 women/12 men) that underwent conventional TAA with mean follow-up of 42 months, and 26 ankles (25 patients, 18 women/7 men) that underwent combined TAA with mean follow-up of 46 months were included. Clinical outcomes, which included ankle range of motion (ROM), the Japanese Society for Surgery of the Foot (JSSF) ankle-hindfoot scale, the Self-Administered Foot Evaluation Questionnaire (SAFE-Q), and complications were compared between the groups.

RESULTS

The preoperative ROM was significantly worse in combined TAA for both dorsiflexion and plantarflexion; however, in the final ROM, there was no significant difference between the groups. There was no significant difference in JSSF scale and SAFE-Q between the groups. Revision rate was 10.9% in conventional TAA and 0% in combined TAA.

CONCLUSION

In this small series, at an average of 3.5 years, we found no significant difference in clinical results between conventional TAA and combined TAA; however, the revision rate was higher in conventional TAA.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

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.

A feature-based statistical shape model for geometric analysis of the human talus and development of universal talar prostheses

Statistical data pertaining to anatomic variations of the human talus contain valuable information for advances in biological anthropology, diagnosis of the talar pathologies, and designing talar prostheses. A statistical shape model (SSM) can be a powerful data analysis tool for the anatomic variations of the talus. The main concern in constructing an SSM for the talus is establishing the true geometric correspondence between the talar geometries. The true correspondence complies with biological and/or mathematical homologies on the talar surfaces. In this study, we proposed a semi-automatic approach to establish a dense correspondence between talar surfaces discretized by triangular meshes. Through our approach, homologous salient surface features in the form of crest lines were detected on 49 talar surfaces. Then, the point-wise correspondence information of the crest lines was recruited to create posterior Gaussian process morphable models that non-rigidly registered the talar meshes and consequently established inter-mesh dense correspondence. The resultant correspondence perceptually represented the true correspondence as per our visual assessments. Having established the correspondence, we computed the mean shape using full generalized Procrustes analysis and constructed an SSM by means of principal component analysis. Anatomical variations and the mean shape of the talus were predicted by the SSM. As a clinically related application, we considered the mean shape and investigated the feasibility of designing universal talar prostheses. Our results suggest that the mean shape of (the shapes of) tali can be used as a scalable shape template for designing universal talar prostheses.

Ankle Height Preservation with the Hind Foot Nail and Iliac Crest Bone Blocks in Patients with Sequelae of Partial or Complete Talus Bone Loss

Introduction:

The management of talus bone loss in trauma is difficult and unsatisfactory. This study assessed whether the height of the ankle was preserved when entire or partial talar bone loss was managed with hind foot intramedullary nail augmented with autogenous rectangular or trapezoidal cortico-cancellous bone blocks from the iliac crest in the presence of active or latent infection.

Materials and methods:

Four patients were included in the study from January 2011 to December 2017. In the first stage, all four patients underwent debridement of the ankle, total or partial excision of the talus, and antibiotic-loaded bone cement spacer (ALBC) placement in the ankle joint. The second stage of the arthrodesis procedure was initiated six to eight weeks after the primary procedure, where these patients underwent arthrodesis with hindfoot nail and bone blocks from the iliac crest.

Results:

All patients were followed-up for an average of 17.6 months (range 12.0 – 32.0 months). The arthrodesis site had united in all these four patients. The AOFAS scores were satisfactory in all patients. One patient underwent nail removal after the arthrodesis site had united.

Conclusions:

The hind foot nail with iliac crest bone block maintains the ankle height and ensures successful arthrodesis. In patients with partial/ complete bone loss with suspicion or confirmation of infection, staging the arthrodesis procedure minimises the chance of complications.

Incorporating 3D Printing Into Your Practice: Lessons Learned

Three-dimensional (3D) printing has greatly benefited medicine, manufacturing vital organs like skin, hearts, kidneys, and livers. Early studies on 3D printing in surgery have consistently reported decreased operative time and improved precision. This technology has gained popularity with orthopaedic surgeons in knee, hip, and shoulder surgeries because 3D printing is associated with enhancing osseointegration. However, this innovation is still not commonly used among foot and ankle surgeons; one reason is that whereas the literature on 3D printing-assisted surgery is populated with studies on operative techniques and clinical outcomes, there exists an ambiguity on how to incorporate this feature into the clinic. Thus, the aim of this technology column is to consolidate and standardize a workflow to guide foot and ankle surgeons on integrating 3D printing into one's practice. We describe a model developed by a single surgeon at one institution who directs a large caseload of 3D-printed foot and ankle surgeries. From the initial patient visit to the interaction between the surgeon and the implant engineering team, to documentation of data adding to the preliminary literature, this work has great implications on streamlining the assimilation of a highly successful technology to improve foot and ankle surgery for both surgeons and patients.Level of Evidence: Level V.

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.

Custom-Made Total Talonavicular Replacement in a Professional Rock Climber: Functional Evaluation With Gait Analysis and 3-Dimensional Medical Imaging in Weightbearing at 5 Years' Follow-Up

With the goal to restore ankle and foot function also in the long term, custom-made prostheses are becoming more frequently possible solutions for severe bone loss and avascular necrosis of the talus. A young professional rock climber was implanted with a custom-made talonavicular prosthesis, and short-term (30 months) assessment has been published. A thorough assessment at the intermediate term (60 months), with state-of-the-art gait and medical imaging analyses, is reported here. Level walking and more demanding motor tasks were analyzed with both a full-body and a multisegment foot protocol on the operated and contralateral limbs. Cone-beam computer-tomography was also used to obtain 3-dimensional (3D) position and orientation of bone models on the operated ankle. These models were also used for a 3D video fluoroscopy analysis, with the ankle in 3 joint positions at the extremes of motion. Distance map analysis was performed to check for possible changes over time of bone morphology and joint contact areas, in all 3 joint positions. Very satisfactory functional results were observed, with large and symmetric joint motion and physiological muscular recruitment even in demanding motor tasks. Distance map analyses revealed that very small morphologic and contact patterns changes occurred in the replaced ankle between 30 and 60 months. Concerns about possible wear of the cartilage in the tibial mortise are not yet supported by experimental evidence.

Total Talus Replacement: Case Series and Literature Review

Custom 3D printed total talus implants have been used successfully as a functional alternative to arthrodesis or amputation in cases of severe talar destruction or loss. However, the ideal material and construct still remains to be elucidated. Current models have been made from aluminum ceramic, cobalt chrome, stainless steel, titanium, or metal combinations. The implants may be constrained (subtalar arthrodesis) or unconstrained (press fit within mortise). They may also be combined with a tibial prosthesis or used in isolation. The majority of currently published case studies examine unconstrained and isolated implants. This case study presents satisfactory 1-y outcomes in 3 cobalt chrome constrained total talar implants used in combination with a tibial prosthesis, and a literature review of total talus replacements.

Metallic 3D Printed Total Talus Replacement: A Case Study

Total talar replacement is a viable treatment option for talar injuries and pathologies. We present a single case study of a 73-year-old female with idiopathic necrosis of the talar which was treated with a total talar replacement prosthesis. A patient specific custom talar prosthesis was created using the mirror image of the contralateral healthy talus obtained using a CT scan of the contralateral limb. The patient underwent surgical resection of the pathologic talus with implantation of the custom talar prosthesis. At the 12 month mark the foot function index (FFI) score improved from 95.9% pre-op to 4.7% post op and american orthopedic foot and ankle score 0 pre-op to 94 post op. Further research and longer followup will be needed, but the current results are very favorable.

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.

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.

Avascular Necrosis of the Talus

Talar osteonecrosis results from trauma to the fragile blood supply to the talus. Many etiologies exist that can cause talar osteonecrosis, with the most common being talar neck fractures. Patients with talar osteonecrosis frequently present with progressive ankle pain and limited range of motion. Treatment strategy depends primarily on the stage of disease. Conservative care in the form of medications and bracing treatment can be beneficial for patients with low functional status and early disease stages. Surgical options also exist for early disease without talar collapse that can potentially preserve the tibiotalar joint. Once talar collapse develops, surgical treatment is move invasive and typically involves an arthrodesis or talus arthroplasty. Although some treatment guidelines exist based on the disease stage, talar osteonecrosis is a complex problem, and treatment strategy should always be determined on a case-by-case basis carefully examining all clinical aspects.

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.

Sixteen-Year Follow-up of Talar Body Prosthesis and Total Ankle Arthroplasty After Traumatic Talar Extrusion: A Case Report

CASE

We report a case of an extruded talus treated with an agility custom talar body prosthesis with total ankle arthroplasty 2 years after the injury. At the 16-year follow-up, the patient has performed remarkably well. At postoperative year 15, she required 1 additional surgery in which the polyethene was exchanged and the medial and lateral gutters were debrided.

CONCLUSION

Talar body prothesis with total ankle arthroplasty may be a viable option for extrusion of the talus.

3D Printed Total Talus Replacement for Avascular Necrosis of the Talus

BACKGROUND

Talus avascular necrosis (AVN) is a challenging entity to treat. Management options depend on disease severity and functional goals. Total talus replacement (TTR) is a treatment option that maintains joint range of motion. The literature on TTR is limited with variability in implant design and material. The purpose of this study was to evaluate outcomes following TTR with a custom 3D printed metal implant.

METHODS

Patients who underwent TTR were retrospectively reviewed over a 3-year period. Basic demographic data and comorbidities were collected. Medical records were reviewed to obtain postoperative and preoperative visual analog scale (VAS) scores, Foot and Ankle Outcome Scores (FAOSs), ankle range of motion, and postoperative complications. Statistical analysis was conducted to compare clinical and patient-reported outcomes pre- and postoperatively. Twenty-seven patients underwent TTR for talar AVN with a mean follow-up of 22.2 months.

RESULTS

Ankle range of motion remained unchanged postoperatively. VAS pain scores improved postoperatively from 7.1 to 3.9 (P < .001). FAOSs improved postoperatively with regard to pain (P < .001), symptoms (P = .001), quality of life (P < .001), and activities of daily living (P < .001). There were 3 complications requiring reoperation in this cohort.

CONCLUSION

3D printed TTRs represent a unique surgical option for patients with severe talar AVN. Patients in this cohort demonstrated significant improvements in pain scores and patient-reported outcomes. TTR allows for symptomatic improvement with the preservation of motion in individuals with talar collapse and AVN.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Application of a Customized Total Talar Prosthesis for Revision Total Ankle Arthroplasty

BACKGROUND

The rate of revision surgery for total ankle arthroplasty (TAA) is higher than for hip and knee arthroplasties. Tibiotalocalcaneal arthrodesis is widely used; however, it requires a large allograft. Thus, the use of a customized total talar prosthesis in combination with the tibial component of TAA (combined TAA) may be an effective strategy for talar component subsidence. This study aimed to evaluate the clinical and radiographic effectiveness of the combined TAA in such revision cases.

METHODS

Between 2000 and 2015, 10 patients (10 women; 10 ankles) were treated using the combined TAA for revision after standard TAA or combined procedures that included the use of a talar body prosthesis. In 6 patients, the tibial component was concurrently replaced. The median follow-up period was 49 months (interquartile range [IQR], 24.5 to 90 months). The Japanese Society for Surgery of the Foot (JSSF) ankle-hindfoot scale score, a numerical rating scale (NRS) pain score, passive range of motion of the ankle, and the presence of osteophytes and degenerative changes in the adjacent joints were assessed preoperatively and at final postoperative follow-up.

RESULTS

The median NRS pain score improved significantly, from 7 (IQR, 6.25 to 8.75) to 2 (IQR, 1 to 3). The median JSSF ankle-hindfoot scale total score improved significantly, from 64 (IQR, 56.25 to 71.5) to 88.5 (IQR, 79.75 to 96). In the subcategories of this scale, the median pain score improved from 20 (IQR, 20 to 27.5) to 35 (IQR, 30 to 40), and the median function score improved from 34 (IQR, 26.5 to 37) to 43.5 (IQR, 39.75 to 46). The median range of motion improved from 29° (IQR, 25.5° to 35°) to 35° (IQR, 31.25° to 43.75°). No significant difference in osteophyte formation was found. Degenerative changes in the adjacent joint were found only in the talonavicular joint.

CONCLUSIONS

The combined TAA, used in revision for postoperative complications after standard TAA or combined procedures including the use of a talar body prosthesis, was associated with improved objective JSSF ankle-hindfoot scale scores, subjective pain assessment, and range of motion in the ankle.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Investigation of the Average Shape and Principal Variations of the Human Talus Bone Using Statistic Shape Model

Due to the complexity of articular interconnections and tenuous blood supply to the talus, talus fractures are often associated with complications (e.g., avascular necrosis). Currently, surgically fusing the talus to adjacent bones is widely used as treatment to talus fractures, but this procedure can greatly reduce mobility in the ankle and hindfoot. Alternatively, customized talus implants have shown an overall satisfactory patient feedback but with the limitation of high expenses and time-consuming manufacturing process. In order to circumvent these disadvantages, universal talus implants have been proposed as a potential solution. In our study, we aimed to develop a methodology using Statistical Shape Model (SSM) to simulate the talus, and then evaluate the feasibility of the model to obtain the mean shape needed for universal implant design. In order to achieve this, we registered 98 tali (41 females and 57 males) and used the registered dataset to train our SSM. We used the mean shape derived from the SSM as the basis for our talus implant template, and compared our template with that of previous works. We found that our SSM mean shape talus implant was geometrically similar to implants from other works, which used a different method for the mean shape. This suggests the feasibility of SSM as a method of finding mean shape information for the development of universal implants. A second aim of our study was to investigate if one scalable talus implant can accommodate all patients. In our study, we focused on addressing this from a geometric perspective as there are multiple factors impacting this (e.g., articular surface contact characteristics, implant material properties). Our initial findings are that the first two principal components should be afforded consideration for the geometrical accuracy of talus implant design. Additional factors would need to be further evaluated for their role in informing universal talus implant design.

Morphometric geometric differences between right and left human tali: A cadaveric study of fluctuating asymmetry via systematic measurement and three-dimensional scanning

Background

Little is known about differences in the size and morphology of the right and left human tali. The present study demonstrates differences between right and left talar morphometric geometric profiles as fluctuating asymmetry in matched pairs of cadaveric specimens.

Methods

In total, 24 tali were collected in this study. All eligible tali were systematically measured with a Vernier caliper and three-dimensional laser scanner, which provided data for further analysis regarding the talar morphometric geometric profiles. Data were calculated to demonstrate differences between the right and left talar profiles using a matched-pair method, including the general size of the talus.

Results

The average talar length was 53.5 mm, the average talar dome height was 31.2 mm, and the average talar body width was 41.3 mm. The average anterior trochlear width, middle trochlear width, posterior trochlear width, and trochlear length were 31.8, 31.2, 28.3, and 30.7 mm, respectively. Eleven matched pairs of intact tali were eligible for the matched-pair study. Paired t-tests showed significant differences in the talar dome height (P = 0.019), middle trochlear width (P = 0.027), and posterior trochlear width (P = 0.016) between the right and left tali. However, there were no significant differences in the surface area or volume between the right and left tali.

Conclusion

Significant differences in the morphometric profile were found between the right and left matched pairs of tali. This basic information indicates that the profile of the contralateral talus may not be used as a single reference to reconstruct or duplicate the talus of interest in certain conditions such as talar prosthesis implantation or customized total ankle replacement.

Ceramic Artificial Talus as the Initial Treatment for Comminuted Talar Fractures

BACKGROUND

Comminuted talar fractures are rare. Generally, this fracture occurs as a result of high-energy injuries. Therefore, this operation is challenging for the surgeon. We started to replace the whole talus with a total talar prosthesis in cases of aseptic talar necrosis in 2005. Based on these results, replacement with a ceramic artificial talus was performed as the initial treatment for comminuted talar fractures.

METHODS

From 2009 to 2016, a total of 6 feet of 6 patients with comminuted talar dome fractures or talar body defects were replaced with a ceramic artificial talus. The patients' mean age was 40.3 years (range, 19-59). Postoperative assessments were performed in accordance with the American Orthopaedic Foot & Ankle Society (AOFAS) ankle/hindfoot score system. Postoperative range of motion and sports activities were also evaluated. Follow-up ranged from 12 to 84 (mean, 46.8) months.

RESULTS

The postoperative AOFAS score was on average 78.8 (64-100). The postoperative range of motion was on average 10 degrees (5-20) for dorsiflexion and 31 degrees (15-50) for plantarflexion. Three patients had returned to sport activities.

CONCLUSION

Prosthetic total talar replacement was a useful procedure for patients with comminuted talar fractures, which had good congruency of the custom-made implant with the adjacent joints, resulting in stability, and maintained ankle function. Furthermore, this procedure could prevent the complications of long-term external fixation and non-weight-bearing walking seen after open reduction and arthrodesis.

LEVEL OF EVIDENCE

Level IV, retrospective comparative study.

Development and Implantation of a Universal Talar Prosthesis

Talar avascular necrosis (AVN) can result in bone collapse with subsequent ankle and subtalar osteoarthritis ending in significant pain and disability. Custom talar body prostheses have been implanted with good results but these are difficult to design, costly and require extensive planning. In the past few years, we have investigated the feasibility of a universal talar replacement prosthesis through multiple studies. This report documents that development and the results from the first patient to receive a universal talar replacement prosthesis. A patient with bilateral talar AVN with collapse had implantation of two universal talar prostheses with final evaluations at 34 months (right) and 12 months (left) post-implantation using visual analog scale, range of motion, SF-36 questionnaire, and personal reflection. The patient had decreased pain, increase range of motion, improvement (or no change) on all domains of the SF-36 and expressed great appreciation for having the procedures done. This report demonstrates the effectiveness and feasibility of a universal talar prosthesis. Continued development of this type of implant can decrease costs, improve access, and provide an acceptable alternative when a custom prosthesis is not possible.

Measurement of talar morphology in northeast Chinese population based on three-dimensional computed tomography

Morphological data of talus are important for the design of talar prostheses. The talar morphology of Chinese population has been rarely reported. This study adopted a three-dimensional (3D) measurement approach to provide accurate data for the anatomical morphology of talus in Northeast Chinese population and compared it with that of foreigners.One hundred forty-six healthy subjects form Northeast China underwent computed tomography (CT) arthrography. 3D digital talar model was reconstructed and thirteen morphological parameters were measured through Mimics and Magics software. Length and breadth indexes of total talus, trochlea, medial and lateral malleolus articular surface were mainly selected. Statistical analysis was conducted by independent-samples and paired-samples t test through SPSS software.All the indexes were normally distributed. No significant difference between left and right talus was identified in either males or females (P > .05). Most of the indexes showed significant sexual differences except the radian of lateral malleolus articular surface and the posterior breadth of trochlea (P < .05). The talar anatomy of Chinese subjects is different from the published data in other populations.The promising approach adopted in this study addresses some inconvenience with previous conventional methods on cadaver specimens. The geometric parameters of talus in Chinese population differ from those in other populations. The talar measurements and morphology analysis in this study suggest that population characteristics should be taken into account. This study will provide references for the design of talar prostheses in Chinese population.

Synovial Metallosis After Ceramic Total Ankle Arthroplasty Treated With a Total Talar Prosthesis: A Case Report

Total ankle arthroplasty is a useful surgical procedure for osteoarthritis of the ankle, but aseptic loosening of components is an issue. We report here a case of aseptic implant loosening with metallosis after total ankle arthroplasty using the TNK ankle (Kyocera, Kyoto, Japan), which occurred despite the components being ceramic. We also report favorable results from our method of treatment using a total talar prosthesis in the revision surgery. During the revision surgery, synovial metallosis was found, probably related to superficial damage to the screw affixing the tibial component to the bone. Because both the tibial and talar components were loose, all the components and the remaining talar bone were removed. A new tibial component and a custom-made alumina-ceramic total talar prosthesis was inserted. Pain relief was achieved and maintained through the latest follow-up visit at 42 months after revision surgery. Dorsiflexion of the ankle improved from 0° to 5° and plantarflexion remained unchanged from its preoperative range of 20°. The American Orthopaedic Foot & Ankle Society ankle-hindfoot score improved from 38 to 80 points. To the best of our knowledge, this is the first reported case of an alumina-ceramic total ankle prosthesis loosening caused by metallosis resulting from screw abrasion. Favorable treatment results were obtained by using a total talar prosthesis in the revision surgery.

Clinical Outcomes of Total Ankle Arthroplasty With Total Talar Prosthesis

BACKGROUND

Total ankle arthroplasty (TAA) has been developed to treat patients with end-stage ankle osteoarthritis (OA). However, there is often difficulty in treating complicated pathologies such as ankle OA with subtalar joint OA and severe talar collapse. Therefore, this study aimed to explore the short-term results and complications of TAA with total talar prosthesis, known as combined TAA, as the new techniques to treat such complicated pathology.

METHODS

We examined postoperative results including ankle range of motion, Japanese Society for Surgery of the Foot (JSSF) scale, and complications. There were 22 patients (15 women), with mean follow-up of 34.9 (range, 24-53 months), and the mean age was 72 (range, 62-80) years. The main indications for combined TAA included osteoarthritis (18 patients), rheumatoid arthritis (3 patients), and talar osteonecrosis with osteoarthritis (one patient).

RESULTS

The mean range of motion improved from 4.0 to 14.4 degrees in dorsiflexion and from 23.8 to 32.0 degrees in plantarflexion. The JSSF scale improved from 50.5 to 91.5 points. Prolonged wound healing occurred in 3 patients, and medial malleolus fracture occurred in 4 patients.

CONCLUSION

Combined TAA was a reliable procedure for the treatment of not only ankle OA following avascular necrosis of talus but also of degeneration of both ankle and subtalar joints.

LEVEL OF EVIDENCE

Level IV, case series.

Total ankle arthroplasty incorporating a total talar prosthesis

Aims

Total ankle arthroplasty (TAA) has become the most reliable surgical solution for patients with end-stage arthritis of the ankle. Aseptic loosening of the talar component is the most common complication. A custom-made artificial talus can be used as the talar component in a combined TAA for patients with poor bone stock of the talus. The purpose of this study was to investigate the functional and clinical outcomes of combined TAA.

Patients and Methods

Ten patients (two men, eight women; ten ankles) treated using a combined TAA between 2009 and 2013 were matched for age, gender, and length of follow-up with 12 patients (one man, 11 women; 12 ankles) who underwent a standard TAA. All had end-stage arthritis of the ankle. The combined TAA features a tibial component of the TNK ankle (Kyocera, Kyoto, Japan) and an alumina ceramic artificial talus (Kyocera), designed using individualized CT data. The mean age at the time of surgery in the combined TAA and standard TAA groups was 71 years (61 to 82) and 75 years (62 to 82), respectively. The mean follow-up was 58 months (43 to 81) and 64 months (48 to 88), respectively. The outcome was assessed using the Japanese Society for Surgery of the Foot (JSSF) ankle-hindfoot scale, the Ankle Osteoarthritis Scale (AOS), and the Self-Administered Foot Evaluation Questionnaire (SAFE-Q).

Results

The mean preoperative JSSF score of the combined TAA and standard TAA groups was 44 (sd 11) and 49 (sd 10), respectively. The mean postoperative JSSF scores were 89 (sd 6.1) and 72 (sd 15), respectively. The mean postoperative JSSF score of the combined TAA group was significantly higher (p = 0.0034). The mean preoperative AOS scores for pain and function in the combined TAA and standard TAA groups were 5.8 (sd 3.3) and 5.5 (sd 3.1), and 8.6 (sd 1.3), and 7.1 (sd 2.9), respectively. The mean postoperative AOS scores of pain and function were 2.5 (sd 2.5) and 2.2 (sd 1.9), and 2.5 (sd 3.3) and 3.4 (sd 2.9), respectively. There were no significant differences between the two groups in terms of postoperative AOS scores. The mean postoperative SAFE-Q scores were: for pain, 76 (sd 23) and 70 (sd 23); for physical function, 66 (sd 25) and 55 (sd 27); for social function, 73 (sd 35) and 62 (sd 34); for shoe-related, 73 (sd 19) and 65 (sd 26); and for general health, 78 (sd 28) and 67 (sd 29), respectively. There were no significant differences between the two groups in terms of postoperative SAFE-Q scores.

Conclusion

Combined TAA resulted in better clinical results than standard TAA. Cite this article: Bone Joint J 2019;101-B:443–446.

3D Printed Total Talar Replacement: A Promising Treatment Option for Advanced Arthritis, Avascular Osteonecrosis, and Osteomyelitis of the Ankle

Advanced ankle arthritis, avascular osteonecrosis, and osteomyelitis of the ankle remain a surgical challenge in the foot and ankle arena with limited treatment options. Multiple medical comorbidities contribute to total loss of the talus. Collapse of the talar body as a complication of total ankle arthroplasty, talectomy in infection, and septic talus necrosis or severe bone defects caused by tumor resection may result in need for total talar replacement. Ankle arthrodesis and tibiocalcaneal fusion after talectomy can produce severe disability of the ankle and foot. Total ankle replacement is a viable option for treatment of end-stage ankle arthritis in appropriate patient populations.

Treatment of Osteonecrosis of the Talus

More than 60% of the talar surface area consists of articular cartilage, thereby limiting the possible locations for vascular infiltration and leaving the talus vulnerable to osteonecrosis. Treatment strategies for talar osteonecrosis can be grouped into four categories: nonsurgical, surgical-joint sparing, surgical-salvage, and joint-sacrificing treatments. Nonoperative and joint-sparing treatments include restricted weight-bearing, patellar tendon-bearing braces, bone-grafting, extracorporeal shock wave therapy, internal implantation of a bone stimulator, core decompression, and vascularized or non-vascularized autograft, whereas joint-sacrificing or salvage procedures include talar replacement (partial or total) and arthrodesis. In patients with a Ficat and Arlet grade-I through III osteonecrosis, evidence in favor of a specific treatment is poor, although tibiotalar or tibiotalocalcaneal arthrodesis may represent a suitable salvage operation.

Fluoroscopic and Gait Analyses for the Functional Performance of a Custom-Made Total Talonavicular Replacement

The present study evaluated the restoration of joint function in a special clinical case: a professional rock climber who underwent an original total talonavicular replacement with a custom-made prosthesis after a complex articular fracture. Full body gait analysis and 3-dimensional joint kinematics using single-plane fluoroscopy were performed on the same day at the 30-month follow-up examination. Gait analysis was performed using stereophotogrammetric, dynamometric, electromyographic, and baropodometric systems. Gait analysis showed good restoration of rotation, as well as moment patterns in the main lower limb and foot joints in the operated leg. At the artificial tibiotalar joint, videofluoroscopic analysis revealed a flexion capability of about 20°, together with a few degrees of motion in the frontal and transverse planes. The neighboring joints of the foot did not present with severe kinematic abnormalities. A full talonavicular replacement can be a viable and effective solution for complex ankle injury sequelae, even in patients with highly demanding functionality.

Analysis of a generic talar prosthetic with a biological talus: A cadaver study

Treatment for talar avascular necrosis is challenging. This study evaluates the feasibility of a generic talar implant by cadaveric assessment. Ten cadaveric ankles were CT-scanned to determine talar implant size. The opposite ankles were CT-scanned with the biological talus and then with the implant. 3D ankle geometry was reconstructed and implant position was compared to the biological talus position. The averages among specimens' positive and negative average-deviations were 0.91 mm and 0.70 mm. Seventy percent of talar dome deviations between the biological talus and implant were within an acceptable range. This study yields promising results to support a generic talus bone prosthetic.

Custom-Made Alumina Ceramic Total Talar Prosthesis for Idiopathic Aseptic Necrosis of the Talus: Report of Two Cases

Two women aged 65 years and 78 years presented to our center with idiopathic necrosis of the talus. In both cases, imaging examinations showed collapse and sclerotic changes of the talar body caused by the necrosis. Both women underwent resection and placement of a third-generation custom-made alumina ceramic total talar prosthesis. Immobilization of the ankle in a short-leg cast for 3 weeks was followed by early rehabilitation. One year and 6 months after surgery, both women were able to walk without pain. Their Japanese Society for Surgery of the Foot ankle-hindfoot scale scores improved from 22 and 29/100 points to 90 and 95/100 points, respectively. To the best of our knowledge, the successful treatments of these two rare cases of idiopathic necrosis of the talus are among only a few reported cases of using a third-generation alumina ceramic prosthesis.

Development of an internally braced prosthesis for total talus replacement

Total loss of talus due to trauma or avascular necrosis, for example, still remains to be a major challenge in foot and ankle surgery with severely limited treatment options. Implantation of a custom made total talar prosthesis has shown promising results so far. Most important factors for long time success are degree of congruence of articular surfaces and ligamentous stability of the ankle. Therefore, our aim was to develop an optimized custom made prosthesis for total talus replacement providing a high level of primary stability. A custom made hemiprosthesis was developed using computed tomography and magnetic resonance imaging data of the affected and contralateral talus considering the principles and technology for the development of the S.T.A.R. prosthesis (Stryker). Additionally, four eyelets for fixation of artificial ligaments were added at the correspondent footprints of the most important ligaments. Two modifications can be provided according to the clinical requirements: A tri-articular hemiprosthesis or a bi-articular hemiprosthesis combined with the tibial component of the S.T.A.R. total ankle replacement system. A feasibility study was performed using a fresh frozen human cadaver. Maximum range of motion of the ankle was measured and ligamentous stability was evaluated by use of standard X-rays after application of varus, valgus or sagittal stress with 150 N. Correct implantation of the prosthesis was technically possible via an anterior approach to the ankle and using standard instruments. Malleolar osteotomies were not required. Maximum ankle dorsiflexion and plantarflexion were measured as 22-0-28 degrees. Maximum anterior displacement of the talus was 6 mm, maximum varus tilt 3 degrees and maximum valgus tilt 2 degrees. Application of an internally braced prosthesis for total talus replacement in humans is technically feasible and might be a reasonable procedure in carefully selected cases with no better alternatives left.

Early results of a novel technique: Hindfoot fusion in talus osteonecrosis prior to ankle arthroplasty: A case series

BACKGROUND

The purpose of this study was to evaluate the clinical outcome of a two staged approach of subtalar arthrodesis followed by TAR for patients with ankle arthritis and AVN talus.

METHODS

Out of total 210 TARs performed at our institute; 7 patients underwent a two staged procedure between 2006 and 2010. All patients had over 3 years of follow up (except one). The clinical results were assessed using AOFAS, WOMAC, SF-36 and patient satisfaction scores.

RESULTS

The mean follow up was 3 years. There was significant improvement in AOFAS and WOMAC (pain and stiffness) from pre-op to 3 years post-op (P<0.05). SF 36 scores improved from pre-op to 3 years post-op for 6/8 domains. 5 patients were satisfied at 3 years for overall surgical outcomes, 4 were satisfied with pain relief. Radiological signs of talar subsidence were noted in 2 patients at year 1. This did not progress at 3 years and did not deteriorate clinical outcome.

CONCLUSION

We recommend our two staged approach to deal with this difficult clinical problem. We believe this approach is safe for TAR surgery where talar vascularity and bone quality is questionable leading to reduced talar subsidence, ischaemic pain and improvement in longevity of TAR.

LEVEL OF EVIDENCE

Evidence IV (Retrospective case series).

Total Talar Replacement for Idiopathic Necrosis of the Talus: A Case Report

Idiopathic osteonecrosis of the talus is a rare but severe condition that directly affects the ability to walk and is difficult to treat either conservatively or surgically. We report the case of a 72-year-old female with idiopathic necrosis of the talus treated with total talar replacement surgery. A custom-made aluminum-ceramic total talar prosthesis was prepared using the mirror image of the computed tomography and radiographic data from the contralateral ankle. The talus was exposed and removed using an anterior approach, and the total talar prosthesis was inserted. The prosthesis was placed in a stable position between the tibia, calcaneus, and navicular, with no signs of instability with ankle joint movement. The ankle was immobilized in a short-leg cast for 3 weeks. At the latest follow-up examination, 2 years after surgery, the patient was walking without pain. Examination of the left ankle showed 20° of dorsiflexion and 40° of plantar flexion. The American Orthopaedic Foot and Ankle Society ankle/hindfoot score was 90, which had improved from a preoperative score of 45. Radiographic examination showed that the prosthesis was in a stable position in the ankle mortise, and no degenerative or destructive changes were observed in the surrounding bones. This is the first reported case of total talar replacement with a prosthesis for idiopathic talar necrosis. Although the long-term outcome is still unknown, this procedure could provide a good treatment option for idiopathic necrosis of the talus.