Talar extrusion is a rare serious lower extremity injury that usually occurs as a result of a high-energy injury when the talus is dislocated from the tibiotalar, subtalar and talonavicular joints. ^, Most cases are open injuries with severe soft tissue injury and injury to the vascular supply to the talus. Extrusion of the talus often results in fracture of the talus or adjacent bones and contamination of the wound. Due to the complexity of the injury, treatment of open isolated talus dislocation and fracture-dislocations is challenging and often associated with complications such as infection, avascular necrosis (AVN), and osteoarthritis. ^,, Currently, the optimal treatment strategy, especially for contaminated open injuries with complete extrusion, is the subject of much debate. Therapeutic options include talus reimplantation, tibiocalcaneal/tibiotalocalcaneal arthrodesis or total talus replacement (TTR). ^,, In recent years, the development of 3D printing offers the possibility of implanting individually fabricated talus prostheses that can be used in trauma indications which account for 9-14 % of all implanted talus replacements. ^, For all types of treatment modalities due to talus extrusion (reimplantation, arthrodesis, replacement), the technique of using a temporary antibiotic cement spacer to eliminate infectious complications is reported in the literature ^.2,3,4,5 We present preliminary encouraging results in a patient with open complete extrusion of the talar body treated with a temporary 3D-molded talar antibiotic cement spacer (3D-MTACS) followed by implantation of a third generation 3D printed TTR.

A 49-year-old patient who suffered an open fracture-dislocation of the talus with talar body extrusion in a motorcycle accident was urgently admitted to the Emergency Department, University Hospital Brno for further treatment in March 2022. ( Fig. 1 A, B) Radiographs and CT of the ankle revealed loss of the talar body, the fractured talar head with medial comminution remained fixed with ligaments in the talonavicular articulation. ( Fig. 1 B-H) The extruded talus body was deformed and contaminated with road debris and grass, brought in a non-sterile bag. ( Fig. 1 B) The polytrauma patient urgently underwent surgical revision of the injured limb with radical debridement of the 15-cm lacerated semi-circular wound on the lateral aspect of the ankle, stabilization with a spanning external fixator across the ankle and insertion of continuous lavage. After weighing all benefits and risks, a staged TTR approach with temporary implantation of a 3D-MTACS was selected to eradicate potential infection in the ankle joint. ( Fig. 2 A) Eighteen days after the injury, the remaining comminuted talar head was removed followed by implantation of a 3D-MTACS with refobacin using an anterior ankle approach. ( Fig. 2 B-E) The 3D-MTACS was prepared perioperatively using a 3D printed mould followed by surface preparation. The 3D printed mould was prepared as a negative cast, printed on a 3D printer based on a mirrored 3D CT reconstruction of the uninjured talus. ( Fig. 2 A) Due to the sufficient stability of the tibia after implantation of the 3D-MTACS, the external fixator was removed and the tibia was immobilized postoperatively in a removable walking boot. The postoperative course and wound healing were uneventful. The patient gradually started with partial weight-bearing after six weeks. Rehabilitation of the ankle with passive and active range of motion was initiated 14 days after 3D-MTACS implantation. The 3D model of the uninjured talus was used for mirroring in the TTR fabrication. For total talus replacement we used constrained 3D custom printed titanium alloy implant with hard layer of diamond-like carbon coating, trabecular caudal surface and two channels for 6.5 mm cancellous screws to secure the implant to the calcaneus (Prospon, Kladno, Czech Republic). ( Fig. 3. A-G) The patient with preserved ankle motion underwent a talus replacement 12 weeks after the injury. The 3D-MTACS was removed using an anterior ankle approach and the cartilage was removed from the anterior, middle, and posterior articular surfaces of the calcaneus. The adjacent articular surfaces on the tibia, fibula, and navicular bone remained intact, and the joint capsule was augmented by a newly formed induced membrane. Using a distractor, a 3D printed TTR was implanted and was fixed to the calcaneus using two 6.5 mm cancellous screws with subsequent reconstruction of the joint capsule. ( Fig. 3 H, I) The patient’s ankle was immobilized in a removable walking boot for 6 weeks. Ankle range of motion exercises were allowed 4 weeks after surgery with gradually increased weight bearing. From week 12 onwards, the patient was allowed to walk without crutches with full weight bearing. At the follow-up examination 36 months after surgery, the range of motion in the sagittal plane was 41° (plantar flexion 15°, dorsal flexion 26°). ( Fig. 4 D, E) The patient reported pain scores ranging from 0 to 2 depending on weather and daily activities. An AOFAS score of 82, Short Form Survey 36 of 85 were recorded and the FFI was 14 %. The patient reported no limitations in performing daily living activities and was fully satisfied with ankle function. After 6 months, the patient returned to work where he continues to work as an automotive mechanic. He has fully returned to his hobbies. There are no radiographic signs of implant loosening. Mild osteophyte formation and osteoarthritic changes are present in the talonavicular and tibiotalar joints, with mild narrowing of the tibiotalar joint space. ( Fig. 4 A-C) Written informed consent for publication of this case and accompanying images was obtained from the patient.

A An initial preoperative clinical photograph of injured lower limb with contaminated semi-circular wound on the lateral aspect of the ankle. B Deformed extruded talus body contaminated with road debris and grass brought in a non-sterile plastic bag. C Preoperative radiographs showing the partial talar loss after extrusion of the talar body. D,E,F Computed tomography scans in sagittal, transverse and coronal planes showing talar body loss and fractured talar head with medial comminution after primary surgical treatment. G,H Computed tomography scans with 3D reconstruction after primary surgical treatment.

A The anatomic talar antibiotic cement spacer prepared perioperatively using a 3D printed mold. The 3D printed mold was prepared as a negative cast, based on a mirrored 3D CT reconstruction of the uninjured talus. B,C Intraoperative photo showing defect after removing remaining fractured talar head and implantation of anatomic talar antibiotic cement spacer. D,E Final intraoperative radiographs showing anatomic talar antibiotic cement spacer in the tibiotalar space.

A-E Individualized 3D modelling of talar prosthesis, cannulated screw channels for fixation of the subtalar joint were simulated. F,G Custom-made 3D printed total talar prosthesis, lateral and caudal view. A trabecular surface created on the caudal surface of the prosthesis to improve osseointegration of the implant into the calcaneus. H Intraoperative photograph of patient’s ankle with constrained custom- made 3D printed total talar prosthesis in situ. I – Intraoperative photograph of the patient’s ankle demonstrating a thickened neocapsule formed by an induced membrane.

A,B,C Follow-up radiographs 3 years after surgery showing implanted constrained custom- made 3D printed total talar prosthesis. D,E Clinical photograph of the ankle at follow-up examination with maximal plantar and dorsal flexion, mediolateral view.

Complete traumatic talus extrusion is an extremely rare injury, accounting for only 2 % of all talus injuries and only 0.06 % of all dislocations. Currently, there is no consensus proposal in the literature on the optimal treatment of these injuries. ^, Three basic techniques have been described that can be used for definitive treatment of talar extrusion: talus reimplantation, arthrodesis, and TTR. Talus reimplantation is the method of first choice according to some recent studies because it allows preservation of range of motion in the ankle, hindfoot alignment, and provides bone mass for eventual reconstructive procedures. ^,,, Smith reports favourable results after early talus reimplantation with only 2 of 19 patients developing infection, but 8 patients when talar extrusion was associated with a fracture of the neck or body of the talus developed talar collapse, avascular necrosis, or significant subtalar osteoarthritis within 2 years. It should be added that Lui et al. reported a risk of infection of 36.5 % in open talar fractures and Vesely et al. reported infectious complications in 2 out of 6 patients after open extrusion with reimplantation. ^, Another treatment modality is an arthrodesis. In the case of talus reimplantation, primary tibiotalocalcaneal arthrodesis can be performed, in the case of a missing talus, primary tibiocalcaneal arthrodesis with bone allograft is an option. Primary arthrodesis represents a definitive solution that alters ankle and hindfoot biomechanics while eliminating joint motion. Tibiotalocalcaneal and tibiotalar arthrodesis are also associated with a relatively high incidence of complications, including nonunion and osteosynthesis failure requiring reoperation.

In our case, an open talus extrusion was combined with a talar neck fracture and talar head comminution. According to the literature, the combination of open talar extrusion with a talar fracture is associated with early AVN collapse or a high risk of infection of the reimplanted talus. ^,,,, Based on these facts, we suggested that reimplantation of the talus would be burdened with a significant risk of complications. The optimal solution to eliminate potential infectious complications was temporary implantation of a 3D-MTACS.

In 2021, Broughton describes the use of 3-D molded anatomic custom talar cement spacers. In addition to technical fabrication tips, he describes 2 case reports in which the 3-D molded anatomic custom talar cement spacer was implanted as a definitive treatment with good functional outcomes at 4 and 11 months, respectively. Although no comparative data currently exist regarding cartilage preservation between non-anatomic and anatomic cement spacers manufactured using 3D techniques, an anatomic, patient-specific spacer may be expected to provide a lower coefficient of friction at the cement–cartilage interface.

In our case, we chose to use a temporary anatomic 3D-MTACS to allow the patient to maintain a sufficient range of motion, to develop induced membrane augmenting the capsule to minimize cartilage damage and prevent infection. This has been supported by the perioperative finding of intact cartilage of adjacent bones and thick induced membrane after 3D-MTACS explantation.

The experience with third generation of TTR implants has shown promising short and medium-term results, however, due to the inhomogeneity of the studies and the lack of long-term results, it is not possible to draw firm conclusions regarding the optimal design or material used in relevant indications (AVN, osteoarthritis, trauma, tumor, rheumatoid arthritis). ^,, Promising results regarding total talar replacement combined with a tibia component (TATTR) were presented by Morita et al. in their study in 2020. The mid-term results give us hope that if tibiotalar arthrosis develops, conversion of the TTR to a TATTR can be performed to preserve the ankle motion in the following years.

Experience with TTR implantation in trauma indications is limited. Most of the reported cases are either case reports or case groups up to 6 patients. ^,,, Indications are non-reconstructable fractures of the body, dome, neck and talar extrusion. To date there have reported in the literature only 4 studies with 5 patients in whom open talar extrusion was defined as an indication for TTR implantation. ^,,, In all cases, a non-anatomic cement spacers were temporarily used prior to the definitive TTR implantation to prevent the infection after open talar extrusion. Results of these case reports are shown in Table 1 . In our case, we observed similar or better clinical results so far without the need for revision surgery. Jennison et al. and Johnson et al. presented systematic reviews (9 studies of 115 patients and 22 studies of 191 patients) that summarized the treatment and resulting outcomes for total talar replacements in all type of indications (previous trauma to the talus, post-traumatic or degenerative arthritis to the tibiotalar joint, avascular necrosis of talus, multiple failed prior interventions and inflammatory arthropathy to tibiotalar joint). Our resulting outcomes are also comparable to those of these studies. ^,

Table 1

Reported cases of total talar replacement for open talar extrusion.

Author	N	Age	Etiology	Type of antibiotic cement spacer and implantation time	Implant	Follow-up	Radiographic Finding	ROM– sagittal plane	SF-36	AOFAS	Functional Status	TTR revisions
Angthong 2014	1	25 y	Open talar extrusion	Non-anatomic antibiotic cement spacer	Unconstrained, isolated Stainless steel total talus	4.6 m	Stable prosthesis- no signs of prosthesis migration		73.7		Full weight bearing without gait aid, able to perform activities of daily living
Gadara 2013	1	14 y	Open talar extrusion Talus preimplantation complicated with infection	Non-anatomic antibiotic cement spacer Tobramycin beds PMMA spacer (7 months)	Unconstrained, isolated Cobalt chrome total talus,porous coating on non-articular surfaces	11 y	Plantar flexed position of prosthesis osteophytic formation	30		75	Occasional pain, walking without device
Ruatti 2017	1	51 y	Open talar extrusion	Non-anatomic antibiotic cement spacer Spacer moulded to fit against the adjacent joint surfaces (6 months)	Constrained, isolated Cobalt chromium total talus with hydroxyapatite coating on caudal surface	2 y	Stable prosthesis- no signs of periprosthetic delineation or loosening	50	82	77	Cycling and hiking on ground level, sporting activities at moderate level
Leonetti 2023	2	27 y 32 y	Open talar extrusion Talus reimplantation complicated with infection Talus reimplantation complicated with infection	Non-anatomic Gentamycin/clindamycin– loaded cement spacer (6 months) Non-anatomic antibiotic cement spacer	Constrained, isolated Cobalt-chromium alloy with porous caudal articular surface Constrained, isolated trabecular titanium Ti6Al4V with porous calcaneal surface	2 y 2 y	Osteoarthritic changes with osteophytes, sclerosis of tibia subchondral bones Osteoarthritic changes, articular space narrowing	30 30		86 (12 months) 74 (12 months)	Pain, functional limitations Unable to walk without pain, morning stiffness	Triple arthrodesis (2 years after TTR) TATTR (2 years after TTR)

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