If you don't remember your password, you can reset it by entering your email address and clicking the Reset Password button. You will then receive an email that contains a secure link for resetting your password
If the address matches a valid account an email will be sent to __email__ with instructions for resetting your password
Talar avascular osteonecrosis (AVN) is a complication that has been very difficult to treat. This complication can lead to osseous collapse following a total ankle arthroplasty (TAA) which limits the viable treatment options even further. Total talus replacement (TTR) is a proposed treatment option in order to maintain function without sacrificing stability. We present a prospective case report on two patients receiving a custom unconstrained TTR after failed TAA with >3 years follow up. Both patients had improvements in their overall range of motion, AOFAS, VAS and SF-36 scores at short term follow up. Both patients returned to their daily activities without restrictions. Most recent radiographs demonstrate a return of hindfoot instability in case 1 while there is no increase in deformity in case 2. Therefore, a custom TTR seems to be a viable option for patients suffering from talar collapse after a TAA.
Avascular osteonecrosis (AVN) of the talus is a devastating complication with limited treatment options. The talus is covered with approximately 60% articular cartilage, thus limiting it’s periosteal blood supply leading to a higher probability of osteonecrosis.1,2,3 The most common etiology is posttraumatic, largely from consequences of talar neck fractures.2,3 Other non-traumatic etiologies include alcoholism, prolonged use of steroids, use of vasopressors, hyperlipidemia, systemic lupus erythematosus and thrombophilia.2,3,4 A complication of talar AVN is often osseous collapse. Talar collapse has also been described following total ankle arthroplasty (TAA). This complication makes treatment difficult. Previous reports recommend revisional tibiotalocalcaneal arthrodesis, often with bulk allografts due to the extensive bone loss. Although, these procedures are extensive with an increased risk of infection and nonunion resulting in low success rates with decreased shock absorption, limb shortening, and decreased propulsion.2,3,5 Some of these poor outcomes even result in amputation. Therefore, the total talus replacement (TTR) was implemented in order to maintain limb length, reduce pain, and regain function without sacrificing biomechanical stability.
Talar implants were first reported as a salvage procedure for talar AVN in 1997.6 These first generation implants involved a talar body along with an anterior peg attaching to the patient’s native talar neck. Due to loosening at this interface, second generation implants were created without anterior pegs although similar adverse results occurred including talar head collapse and prosthetic loosening. Therefore, a 3rd generation total talar replacement was described by Taniguchi et. al which were complete replacements of the talus with ceramic or metal material. They described favorable results in treating post traumatic and idiopathic talar AVN.1-4 Custom total talus replacements have also evolved into unconstrained vs constrained. Constrained TTR are either fixated to the navicular, calcaneus, or both while unconstrained don’t incorporate fixation to adjacent bones thus maintaining its articulation and natural motion.
Custom total talus replacements are increasing in popularity due to these favorable results. Recently published literature involves the use of a custom made total talus replacement for a variety of treatment pathologies with good results. Although, there is still little research on viable treatment options using unconstrained TTR after a failed TAA. There are even fewer case reports with prospectively collected data.
In this case report, we present two patients who underwent a total talus replacement as a salvage procedure after failed total ankle replacement with talar aseptic collapse. After performing a literature review, there is limited research on this salvage procedure following a talar body collapse after total ankle arthroplasty using a custom CT guided 3D printed cobalt-chromium 3rd generation unconstrained total talus replacement.
Both patients provided their informed consent for publication of this case report.
A 61 yo healthy female originally presented to clinic with progressive hindfoot and ankle pain. She was presenting with a flexible flatfoot deformity and reducible ankle valgus (Figure 1). The patient was educated on surgical treatment options which included a staged procedure to correct her foot deformity first, then addressing her ankle deformity. This would provide the patient with increased stability and increased survivorship of the projected ankle implant. She underwent a flexible flatfoot surgical correction after failing conservative care which included a lateral column lengthening, posterior tibial tendon advancement, and a medial cuneiform plantarflexory osteotomy (Figure 2). She continued to have ankle pain and slight valgus deformity thus undergoing a fixed bearing TAA (Wright Medical, Memphis, TN). She had returned to regular activities with minimal complaints. Full weight bearing radiographs were obtained at one year post operatively (Figure 3). After a year of significant pain relief and overall satisfaction, a new onset of right ankle pain began. 18 months following her initial TAA, this pain progressed to 8/10. Her activities of daily living significantly diminished. She was unable to bear weight without her controlled ankle motion (CAM) boot and use of a knee scooter. Radiographs and a CT scan were obtained of her right ankle (Figure 4 & 5). These images portrayed a stable tibial component with talar component subsidence and significant talar body collapse. There was no involvement of the talonavicular joint, and the calcaneal posterior facet was intact showing minimal arthritic changes. Inflammatory markers and ankle joint aspiration were evaluated returning negative results for infection or joint sepsis.
Because of the significant talar collapse and aseptic loosening of the talus, salvage procedures were offered including tibiotalocalcaneal fusion or revision TAA with a total talus. The patient ultimately elected to undergo a total talus replacement as a salvage procedure.
The patient was consented for a total talus replacement using a custom 3D printed cobalt-chromium implant (Additive Orthopedics, Little Silver, NJ). The tibial component of her TAA (Wright Medical, Memphis, TN) was stable and therefore could be retained. A contralateral ankle CT was ordered to obtain the 3D anatomic replica for the operative side (Fig. 5). The implant talar dome was made custom to match the polyethylene surface of the total ankle implant. A standard anterior ankle approach was utilized, the old polyethylene and talar component were explanted. The necrosed talus was excised (Fig. 6&7). A total talus trial was inserted and appropriately sized before the final custom total talus and new polyethylene were implanted (Figs. 8&9).
Within 6 months follow up, she was able to return to full weight bearing without any restrictions. Radiographs demonstrate a stable implant with maintained deformity correction (Figure 11). Objectively, she regained intrinsic function throughout her ankle joint while increasing her preoperative dorsiflexion and plantarflexion range of motion as well as gaining strength to her lower extremity. The patient progressed very well throughout the initial postoperative phase. Her sutures were removed at 3 weeks and she began protected weight bearing in a CAM walking boot. At her 12 month follow up visit, she was doing very well and had returned to her daily activities without any new complaints. At 24 months, she remained happy with her surgical results. She had maintained full weight bearing status activities without any restrictions while wearing a well supportive shoe with insert. Radiographs were obtained in office with evidence of no loosening or peri cystic changes although she remained unstable throughout her hindfoot complex. The patient was counseled on the importance of external support and to avoid barefoot activities. Most recent radiographs, 3 years post operatively (Figure 12) demonstrate an increase in talar declination, hindfoot valgus, and collapsing longitudinal medial arch similar to her pre operative values.
Intraoperatively, ankle joint range of motion improved from a preoperative value of 2 degrees dorsiflexion to 11 degrees while knee extended (Figure 13). Her total range of motion (ROM) improved from 32 degrees to 51 degrees and has remained improved 24 months postoperatively. Subjectively, her pain decreased from a preoperative level of 8 to 2 at her last follow up. She also had improvements in her American Orthopedic Foot and Ankle Society (AOFAS) ankle-hindfoot score from 28 to 79. Based on her Short Form Survey (SF-36), she has shown improved outcomes in her reported values (Table 1).
Table 1Results for case 1. Pre, 6 month and 24 month postoperative ROM, AOFAS, VAS,SF-36 scores.
An active 77 year old male presented to clinic with worsening right ankle pain. The patient had received bilateral mobile bearing TAA 8 years prior. He continued to have significant right ankle pain with loss of motion affecting his daily activities. Preoperative imaging confirmed talar component loosening with moderate talar body collapse and talar body fracture, as well as ballooning osteolysis involving the medial distal tibia (Figure 14). Surgical options were discussed with the patient. The patient elected to undergo attempted salvage procedure with desire to maintain ankle joint range of motion.
The patient underwent a right ankle hardware removal, revision TAA with a fixed bearing stemmed tibial component (Wright Medical, Memphis, TN), and total talus replacement using a 3D custom printed cobalt-chromium implant (Additive Orthopedics, Little Silver, NJ). A standard anterior ankle approach was performed, the components were removed (Figure 15) and a size 3 long tibial component with size 14 polyethylene component were inserted along with the custom total talar component. In addition, the osteolysis was backfilled with a mixture of calcium phosphate and autograft obtained from the viable portion of the extruded talus (Figure 16, Figure 17).
After four weeks of strict non weight bearing, the patient progressed to partial protected weight bearing in a CAM boot. Physical therapy was started at this time for a total of 6 weeks. The patient was transitioned out of his boot into a regular supportive tennis shoe with insert at 2 months. At two months postoperatively, radiographs revealed stability of his tibial and talar components as well as increasing radiodensity within the tibial osteolysis. Within 5 months, the patient reported large subjective improvements to his pain. He was able to return to the golf course within 6 months postoperatively without any restrictions. He returned 12 months later with new complaints of tarsal tunnel syndrome as well as plantar fasciitis. Radiographs revealed stability of his implants with no other acute osseous findings. Noncontrast MRI confirmed an increase in the plantar fascial band correlating to his clinical symptoms. After failing conservative treatment, he subsequently underwent a partial plantar fasciectomy and tarsal tunnel release. He then went on to heal uneventfully with at-home exercises. He was seen 16 months postoperatively where radiographs were obtained. They demonstrate stability of his implants without new cystic changes (Figure 18). His SF-36 scores demonstrated an improvement in nearly all sections. He continues to stay active on the golf course without any complaints. Most recent clinical radiographs were obtained 3 years s/p total talus arthroplasty (Figure 19). The implant continues to show stability without migration or subluxation within the ankle joint.
As seen in Table 2, his visual analog scale (VAS) decreased from 7 to 2 postoperatively. AOFAS scores improved from 40 to 80 at his final follow up. The biggest improvement was his improvements in range of motion from 20 to 39 degrees of full ROM (Figure 20). Fig. 4
Table 2Results of case 2. Pre and 16 month postoperative ROM, AOFAS, VAS, SF-36 scores.
The talar implant was first introduced by Harnroongroj and Vanadurongwan in 1997. This first generation prosthesis was composed of a talar body with an anterior peg attaching to the patient's native talar head and neck. This 8 patient case series resulted in satisfactory results 5–15 years postoperatively.
Subsequently, second generation implants were created. These implants removed the anterior peg and attachment into the talar head and neck. These implants also showed promising results although talar head collapse was reported in some patients. Taniguchi et al. then reported on third generation implants which consisted of an individually made alumina ceramic total talus prosthesis. With an average of 52.8 months of follow up, there were no required revisional surgeries with improvements in pain, function, and alignment. They concluded, “prosthetic total talar replacement is a useful procedure for patients with osteonecrosis of the talus.”
Taniguchi et al. produced these implants from contralateral CT scans followed by generating a wire model with topographic changes in 2 mm intervals. After the model was complete, a sterolithographic model was casted.
Since then, technology has been advancing in the field of 3D printing. Metal additive manufacturing is becoming substantially faster and more accessible for use. Tracey et al. tested this technology by creating a synthetic talus using contralateral computer aided drafting (CAD) with electron beam melting (EBM). 14 patients were treated with talar AVN using a custom CT guided 3D printed 3rd generation nickel-plated cobalt total talus prosthesis. In this study, talar arc length, talar height, and talar width were all restored and maintained using this technique therefore making this a viable and salvageable option for talar AVN. They suggest a wider number of pathologies are suitable for a total talus replacement including revision total ankle replacement where “restoration of talar alignment and anatomy, synthetically, could be beneficial in these patients.”
Several reports explore utilizing a synthetic talus replacement after a failed total ankle replacement. Tsukamoto et al. described a 56 year old woman with RA who received a total talus implant after failed STJ fusion and talar collapse following a total ankle replacement. The patient was subsequently distracted within a Taylor Spatial Frame and received a custom CT guided total talus replacement created with alumina ceramic. At two years, the patient experienced 0/10 pain with no limitations to normal activities.
Wagener et al. documented 12 patients who underwent a custom talus replacement following talar collapse after total ankle arthroplasty. These implants were not total implants but instead custom tali assembled and designed to minimize resection of the remaining healthy bony structures which were used for anchorage points. Although, after an average follow up of 6.9 years, 75% reported satisfied/very satisfied results with 11/12 patients revealing no radiographic loosening.
Recent literature describes the use of total talus replacement with subsequent TAA. Akoh et. al. describes a case report of a patient with IgG deficiency and chronic steroid usage suffering with an unreconstructable talus and tibial sided arthritic changes. The patient received a tibial component STAR with mobile bearing polyethylene liner as well as a 3D printed cobalt chromium custom total talus replacement. At 1 year follow up, both components were well positioned without evidence of failure.
West et al. also recently presented a case report involving 3 patients undergoing a combination of a constrained total talus replacement with STAR tibial prosthetic. Two of the three patients were back to low impact activities without pain and without loosening or cystic changes 12-16 months post operatively. One patient required revision of the tibial component due to loosening.
Further studies report outcomes of custom made total talus replacements for avascular necrosis of the talus. Tonogai et al. investigated the outcomes of two cases of idiopathic talar AVN treated with custom total aluminum ceramic talar prosthesis. They found satisfactory results without degenerative or destructive changes within the surrounding joints. There was also no evidence of migration on the postoperative CT images.
Kadakia et al. retrospectively reviewed 27 patients with talar AVN subsequently undergoing custom TTR. Majority of their implants consisted of cobalt chromium while the newer implants consisted of cobalt chromium with titanium nitride coating due to recent findings demonstrating decreased wear patterns of adjacent joints. At an average of 22.2 months of follow up, ankle joint range of motion remained unchanged but there were improvements of VAS scores, and FAOS scores regarding pain, symptoms, quality of life and activities of daily living. They concluded that TTR for severe talar AVN was a viable option, at least in the short term follow up.
Scott et al. also described results of patients undergoing custom total talus implants from talar AVN (5 following trauma, 2 following systemic chemotherapy, and 1 following stress fracture). At an average follow up of 12.8 months, there were statistical improvements of VAS and FAOS scores. There was also no change in radiographic alignment parameters when measuring tibiotalar alignment, talar tilt angle, meary's angle, and talar declination angle. They concluded that custom TTR is a promising treatment option for severe talar AVN.
Our prospective case study reports on two patients undergoing an unconstrained custom total talus replacement after a failed TAA with talar aseptic collapse. Our first case demonstrates a 61 year old female who received a custom 3D printed cobalt-chromium implant following total talar collapse after failed TAA. Our second case demonstrates the results of a 77 year old male who presented with talar body chronic fracture nonunion and early collapse following failed TAA with a mobile bearing implant from an outside provider. The patient underwent a custom 3D printed cobalt-chromium total talus replacement with a fixed bearing total ankle revision. Both patients have shown consistent positive results at their most recent follow up visit. They have maintained their functional status and have returned to their daily activities.
This prospective study shows results for total talus replacement, consistent to prior studies. Both of our patients were able to return to their activities of daily living without any restrictions. They also showed improvements to function and range of motion. There were noticeable radiographic findings after 3 years of follow up. The patient in case 1, demonstrated instability within the hindfoot similar to her pre operative values. This finding may guide future pre operative planning with unconstrained vs constrained implants. The patient in case 2, demonstrated a stable total talus and total ankle implant 3 years post operatively. Therefore, from these findings, we have concluded that an unconstrained custom total talar implant appears to be a promising salvage option for patients with failed TAA with aseptic talar collapse at least in short term follow up. Longer follow up is required in determining long term survivorship.
Declaration of Competing Interest
The authors declare there are no conflicts of interest in this report.
Informed patient consent
The authors declare that informed patient consent was taken from all the patients.
There were no outside funding or grants provided to any of the authors in support or preparation of this work. The authors nor their families received any payments, benefits, commitment or agreement to provide such benefits from a commercial entity. Jason Nowak, DPM, FACFAS consults for Additive Orthopaedics.
Control for Bias: Steps were taken to limit bias within this paper. These patients were randomly selected not based on results but on the amount of follow up and appropriate amount of collected data for our interpretation. These patients completed their collected data without the oversight or guidance of a physician involved within the study. Our practice is a Center of Excellence for Additive Orthopaedics. This did not influence our decision to publish, nor were the results/data skewed in any way to promote “positive” findings based on industry influence.
Off Label Usage: The usage of Patient Specific Talus Spacer – H200001, has only recently been approved by The Center for Devices and Radiological Health (CDRH) of the Food and Drug Administration (FDA) in early March 2021 for “adult patients only who have AVN of the ankle joint.” Both of our patients received their implants prior to approval by the FDA, therefore it’s use was considered off-label. During our multiple clinical experiences with these patients, this fact was fully explained to the patients. Before proceeding with the proposed surgical intervention, full consent was achieved from both patients. Consent:Both patients were asked and agreed to have their demographics, photos, and collected data to be presented in this article for publication.
This paper highlights the results using custom total talus replacements for a specific etiology within the foot and ankle. Our results, although positive, are limited to a short follow up. The reader should note the complexity of this procedure with narrow treatment indications. The purpose of this paper is to publish on short term data using our purposed treatment after a failed total ankle arthroplasty. There has not been sufficient amounts of literature promoting this procedure for long term improvements. Further research with longer follow up is necessary.
An alumina ceramic total talar prosthesis for osteonecrosis of the talus.
J Bone Joint Surg American Volume.2015; 97: 1348-1353